<p class="jove_content"> Les auteurs sont reconnaissants pour les contributions artistiques de Hyewon Cooper. </p>

<ol>
	<li>Whitear, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chordotonal+organs+in+Crustacea.">Chordotonal organs in Crustacea.</a> <em style='font-style: italic'>Nature</em>. <b>187</b>, 522-523 (1038).</li><li>Alexandrowicz, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+comparative+anatomy+of+leg+propriocetors+in+some+decapod+Crustacea.">The comparative anatomy of leg propriocetors in some decapod Crustacea.</a> <em style='font-style: italic'>J. Mar. Biol. Assoc. U.K</em>. <b>52</b> (3), 605-634 (1972).</li><li>Hartman, H. B., Boettiger, E. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+functional+organization+of+the+propys-dactylus+organ+in+Cancer+irroratus+Say.">The functional organization of the propys-dactylus organ in Cancer irroratus Say.</a> <em style='font-style: italic'>Comp. Biochem. Physiol</em>. <b>22</b>, 651-663 (1967).</li><li>Cooper, R. L., Hartman, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responses+of+the+bender+apodeme+tension+receptors+in+the+Dungeness+crab,+Cancer+magister.">Responses of the bender apodeme tension receptors in the Dungeness crab, Cancer magister.</a> <em style='font-style: italic'>Comp. Biochem. Physiol. A Physiol</em>. <b>109</b> (2), 479-486 (1994).</li><li>Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+proprioceptive+neurons+on+chordotonal+organs+in+the+crab,+Cancer+magister.">Mapping proprioceptive neurons on chordotonal organs in the crab, Cancer magister.</a> <em style='font-style: italic'>Crustaceana</em>. <b>81</b> (4), 447-475 (2008).</li><li>Burke, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+organ+for+proprioception+and+vibration+sense+in+Carcinus+maenas.">An organ for proprioception and vibration sense in Carcinus maenas.</a> <em style='font-style: italic'>J. Exp. Biol</em>. <b>31</b>, 127-138 (1953).</li><li>Hill, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> <em style='font-style: italic'>First and Last Experiments in Muscle Mechanics</em>. , (1970).</li><li>Stuart, D. G., Mosher, C. C., Gerlach, R. L., Reinking, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+arrangement+and+transducing+properties+of+Golgi+tendon+organs.">Mechanical arrangement and transducing properties of Golgi tendon organs.</a> <em style='font-style: italic'>Exp. Brain Res</em>. <b>14</b> (3), 274-292 (1972).</li><li>Macmillan, D. L., Dando, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tension+receptors+on+the+apodemes+of+muscles+in+the+walking+legs+of+the+crab,+Cancer+magister.">Tension receptors on the apodemes of muscles in the walking legs of the crab, Cancer magister.</a> <em style='font-style: italic'>Mar. Behav. Physiol</em>. <b>1</b> (1-4), 185-208 (1972).</li><li>B&#233;vengut, M., Simmers, A. J., Clarac, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Central+neuronal+projections+and+neuromuscular+organization+of+the+basal+region+of+the+shore+crab+leg.">Central neuronal projections and neuromuscular organization of the basal region of the shore crab leg.</a> <em style='font-style: italic'>J. Comp. Neurol</em>. <b>221</b> (2), 185-198 (1983).</li><li>El Manira, A., Cattaert, D., Clarac, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monosynaptic+connections+mediate+resistance+reflex+in+crayfish+(Procambarus+clarkii)+legs.">Monosynaptic connections mediate resistance reflex in crayfish (Procambarus clarkii) legs.</a> <em style='font-style: italic'>J. Comp. Physiol. A</em>. <b>168</b> (3), 337-349 (1991).</li><li>Le Bon-Jego, M., Cattaert, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibitory+component+of+the+resistance+reflex+in+the+locomotor+network+of+the+crayfish.">Inhibitory component of the resistance reflex in the locomotor network of the crayfish.</a> <em style='font-style: italic'>J. Neurophysiol</em>. <b>88</b> (5), 2575-2588 (2002).</li><li>Ray, D. L., Clarac, F., Cattaert, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+analysis+of+the+sensory+motor+pathway+of+resistance+reflex+in+crayfish.+I.+Multisensory+coding+and+motor+neuron+monosynaptic+responses.">Functional analysis of the sensory motor pathway of resistance reflex in crayfish. I. Multisensory coding and motor neuron monosynaptic responses.</a> <em style='font-style: italic'>J. Neurophysiol</em>. <b>78</b> (6), 3133-3143 (1997).</li><li>Wiersma, C. A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vergleichende+Untersuchungen&#252;ber+das+periphere+Nerve-muskelsystem+von+Crustaceen+(Comparative+studies+on+the+peripheral+nerve-muscle+system+of+crustaceans).">Vergleichende Untersuchungen&#252;ber das periphere Nerve-muskelsystem von Crustaceen (Comparative studies on the peripheral nerve-muscle system of crustaceans).</a> <em style='font-style: italic'>J. Comp. Physiol</em>. <b>19</b>, 349-385 (1933).</li><li>Wiersma, C. A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Movement+receptors+in+decapod+crustacea.">Movement receptors in decapod crustacea.</a> <em style='font-style: italic'>J. Mar. Biol. Assoc. U.K</em>. <b>38</b> (01), 01-143 (1959).</li><li>Hartman, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tension+receptors+on+the+closer+muscle+apodeme+in+the+walking+legs+of+the+blue+crab+Callinectes+sapidus.">Tension receptors on the closer muscle apodeme in the walking legs of the blue crab Callinectes sapidus.</a> <em style='font-style: italic'>J. Comp. Physiol. A</em>. <b>157</b> (3), 355-362 (1985).</li><li>Holsinger, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> <em style='font-style: italic'>The effect of regional phenotypic differences of Procambarus clarkii opener muscle on sarcomere length, fiber diameter, and force development MSc thesis [dissertation]</em>. , (2013).</li><li>Parsons, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+morphology+and+ultrastructure+of+tension+receptors+in+the+walking+legs+of+the+crab,+Carcinus+maenas.">The morphology and ultrastructure of tension receptors in the walking legs of the crab, Carcinus maenas.</a> <em style='font-style: italic'>Cell Tissue Res</em>. <b>211</b> (1), 139-149 (1980).</li><li>Parsons, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responses+and+central+interactions+of+tension+receptors+in+the+leg+muscle+of+Carcinus.">Responses and central interactions of tension receptors in the leg muscle of Carcinus.</a> <em style='font-style: italic'>Comp. Biochem. Physiol. A Physiol</em>. <b>72</b> (2), 391-399 (1982).</li><li>Tryba, A. K., Hartman, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+responses+of+series+force+receptors+innervating+the+opener+muscle+apodeme+in+the+blue+crab,+Callinectes+sapidus.">Dynamic responses of series force receptors innervating the opener muscle apodeme in the blue crab, Callinectes sapidus.</a> <em style='font-style: italic'>J. Comp. Physiol. A</em>. <b>180</b> (3), 215-221 (1997).</li><li>Whitear, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+fine+structure+of+crustacean+proprioceptors.+I.+The+chordotonal+organs+in+the+legs+of+the+shore+crab,+Carcinus+meanas.">The fine structure of crustacean proprioceptors. I. The chordotonal organs in the legs of the shore crab, Carcinus meanas.</a> <em style='font-style: italic'>Philos. Trans. R. Soc. Lond. B Biol. Sci</em>. <b>245</b> (725), 291-325 (1962).</li><li>Whitear, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+fine+structure+of+crustacean+proprioceptors.+II.+The+thoracico-coxal+organs+in+Carcinus,+Pagurus+and+Astacus.">The fine structure of crustacean proprioceptors. II. The thoracico-coxal organs in Carcinus, Pagurus and Astacus.</a> <em style='font-style: italic'>Philos. Trans. R. Soc. Lond. B Biol. Sci</em>. <b>248</b> (752), 437-456 (1965).</li><li>Leksrisawat, B., Cooper, A. S., Gilberts, A. B., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Muscle+Receptor+Organs+in+the+Crayfish+Abdomen:+A+Student+Laboratory+Exercise+in+Proprioception.">Muscle Receptor Organs in the Crayfish Abdomen: A Student Laboratory Exercise in Proprioception.</a> <em style='font-style: italic'>J. Vis. Exp</em>.  (45), e2323 (2010).</li><li>Baierlein, B., Thurow, A. L., Atwood, H. L., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane+Potentials,+Synaptic+Responses,+Neuronal+Circuitry,+Neuromodulation+and+Muscle+Histology+Using+the+Crayfish:+Student+Laboratory+Exercises.">Membrane Potentials, Synaptic Responses, Neuronal Circuitry, Neuromodulation and Muscle Histology Using the Crayfish: Student Laboratory Exercises.</a> <em style='font-style: italic'>J. Vis. Exp</em>.  (47), e2322 (2011).</li><li>Delaney, K., Gelperin, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+interneurons+controlling+fictive+feeding+in+Limaxmaximus;+I.+Anatomy+and+criteria+for+re-identification.">Cerebral interneurons controlling fictive feeding in Limaxmaximus; I. Anatomy and criteria for re-identification.</a> <em style='font-style: italic'>J. Comp. Physiol. A</em>. <b>166</b>, 297-310 (1990).</li><li>Hartman, H. B., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regeneration+and+molting+effects+on+a+proprioceptor+organ+in+the+Dungeness+crab,+Cancer+magister.">Regeneration and molting effects on a proprioceptor organ in the Dungeness crab, Cancer magister.</a> <em style='font-style: italic'>J. Neurobiol</em>. <b>25</b> (5), 461-471 (1994).</li><li>Hartman, H. B., Austin, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proprioceptor+organs+in+the+antennae+of+Decapoda+Crustacea.">Proprioceptor organs in the antennae of Decapoda Crustacea.</a> <em style='font-style: italic'>J. Comp. Physiol</em>. <b>81</b> (2), 187-202 (1972).</li><li>Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+sensory+processes+during+limb+regeneration+in+adult+crayfish.">Development of sensory processes during limb regeneration in adult crayfish.</a> <em style='font-style: italic'>J. Exp. Biol</em>. <b>201</b> (Pt 11), 1745-1752 (1998).</li><li>Chung, Y. -. S., Cooper, R. M., Graff, J., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+acute+and+chronic+effect+of+low+temperature+on+survival,+heart+rate+and+neural+function+in+crayfish+(Procambarus+clarkii)+and+prawn+(Macrobrachium+rosenbergii)+species.">The acute and chronic effect of low temperature on survival, heart rate and neural function in crayfish (Procambarus clarkii) and prawn (Macrobrachium rosenbergii) species.</a> <em style='font-style: italic'>Open J. Mol. Int. Physiol</em>. <b>2</b> (3), 75-86 (2012).</li><li>Blundon, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+temperature+and+thermal+history+on+neuromuscular+properties+of+two+crustacean+species.">Effects of temperature and thermal history on neuromuscular properties of two crustacean species.</a> <em style='font-style: italic'>J. Comp. Physiol. B</em>. <b>158</b> (6), 689-696 (1989).</li><li>Cooper, R. M., Schapker, H., Adami, H., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+and+ventilatory+measures+in+crayfish+during+copulation.">Heart and ventilatory measures in crayfish during copulation.</a> <em style='font-style: italic'>Open J. Mol. Int. Physiol</em>. <b>1</b> (3), 36-42 (2011).</li><li>Bierbower, S. M., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanistic+action+of+carbon+dioxide+on+a+neural+circuit+and+NMJ+communication.">The mechanistic action of carbon dioxide on a neural circuit and NMJ communication.</a> <em style='font-style: italic'>Journal of Experimental Zoology</em>. , (2013).</li><li>Bierbower, S. M., Shuranova, Z. P., Viele, K., Cooper, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensory+systems+and+environmental+change+on+behavior+during+social+interactions.">Sensory systems and environmental change on behavior during social interactions.</a> <em style='font-style: italic'>Brain Behav</em>. <b>3</b> (1), 4-13 (2013).</li></ol>

<p class="jove_content"> Les auteurs déclarent qu&#39;ils n&#39;ont aucun intérêt financier concurrents. </p>

<p class="jove_content"> Le but de cette série d&#39;expériences est une) pour enseigner et exposer les principes fondamentaux d&#39;enregistrements extracellulaires d&#39;un organe proprioceptive identifiable et le nerf de tension et 2) de souligner l&#39;importance de la cartographie anatomique par rapport à la fonction physiologique des systèmes sensoriels particuliers. Cette approche expérimentale et les modèles animaux utilisés sont peu coûteux et relativement facile à réaliser dans les laboratoires d&#39;enseignement de neurophysiologie. </p><p class="jove_content"> Les neurones des organes chordotonaux sont de deux types fonctionnels spécifiques, ceux qui répondent au mouvement et à ceux qui ont répondu à des positions statiques. Enregistrements de cellules individuelles à partir d&#39;une variété d&#39;organes chordotonaux, quel que soit le joint est examiné, ont montré que cela soit le cas <sup>3,5.</sup> En effet, les organes chordotonaux associés aux articulations des antennes de homards révèlent les deux mêmes types sensoriels et l&#39;anatomie de base <sup>27.</sup> En plus de l&#39;existence de deux types de neurones (mouvement et positisur), les neurones ont la même disposition anatomique sur leurs fils élastiques respectifs. Le grand soma située proximale sur le brin tendance à appartenir à des neurones sensibles de mouvement dynamique. Les neurones qui signalent des positions statiques ont petit soma et sont situés distale. Ces cellules sont activité tonique. La commune de PD ne contient qu&#39;un seul organe chordotonal alors qu&#39;il ya deux organes chordotonaux à la carpe-propodus (CP) et merus-carpe (MC) joints. </p><p class="jove_content"> La dissection d&#39;exposer structures proprioceptives dans crabes bleus <em>(C. sapidus)</em> pour l&#39;enregistrement électrophysiologique nécessite une stratégie qui permet aux mouvements articulaires aient lieu dans les positions naturelles pendant l&#39;enregistrement de neurones sensoriels. Le nerf de tension pour le muscle ouvreur à la jambe de la marche est un très beau nerf composé de plusieurs neurones. Sauf soin est pris, le nerf de la tension ainsi que le nerf moteur innervant le muscle à stimuler, peuvent être endommagés au cours de cette dissection. Pourenregistrements optimales des électrodes d&#39;aspiration doivent être adaptées à la taille du nerf. Les enregistrements sont facilement accessibles dans un laboratoire de l&#39;élève à l&#39;aide d&#39;un 30-40X microscope de dissection et micromanipulateurs bas de gamme. </p><p class="jove_content"> Futures expériences qu&#39;il serait intéressant de poursuivre avec les organes chordotonaux communes seraient à examiner les profils structurels et physiologiques pendant la régénération de la jambe dans différentes espèces à différents stades du cycle de vie comme une suite à une première étude qui a utilisé <em>Cancer magister</em> <sup>19,26</sup> . Questions restent à résoudre sont: 1) ne la distribution et de l&#39;organisation des neurones artificielles dépendent de l&#39;âge de l&#39;animal lors de la régénération d&#39;un membre, 2) sont les projections axonales à la CNS (ventrale cordon nerveux) dans une branche de régénération fonctionnelle ou faut-il prendre le temps et l&#39;utilisation conjointe d&#39;établir des connexions fonctionnelles, et 3) ce qui se passe aux axones sectionnés proximale au plan de autotomie lorsque le membre est autotomized? <sup>28</sup> </p><p class="jove_content"> Crustacés conformes aux conditions environnementales et leur température environnante, mais il est difficile de savoir comment ils maintiennent la coordination au sein d&#39;un circuit neuronal neurones modifient leur activité en réponse aux changements de température. Un faible taux de changement pourrait permettre à l&#39;animal un certain temps d&#39;acclimatation alors un changement rapide peut not29, 30. Les changements physiologiques de pH ou osmolarité en raison du métabolisme, le comportement <sup>31,</sup> ou l&#39;impact environnemental peuvent présenter des défis semblables à des circuits neuronaux impliqués dans la proprioception. Ces préparations de crustacés sont idéales pour faire face à ces types de problèmes parce que leur fonction est bien caractérisé au niveau d&#39;une seule cellule. </p><p class="jove_content"> Dans ce protocole, nous avons démontré l&#39;importance physiologique de neurones de traction en force générée par le muscle ouvreur de surveillance. Ces récepteurs de tension peuvent être attribués à leur emplacement dans la apodeme en utilisant des procédures de coloration. Cesneurones, comme chez les mammifères, détectent vigueur à différents niveaux et de recruter des neurones supplémentaires comme la force augmente. La fréquence de l&#39;activité est liée à la fréquence de stimulation du neurone moteur jusqu&#39;à ce que la saturation est atteinte en réception. L&#39;utilisation d&#39;un protocole de libération rapide avec l&#39;articulation de dactyle fléchies, l&#39;activité de la tension disparaît rapidement mais revient ensuite sur regagner tension dans une commune en pleine extension. Il s&#39;agit d&#39;un mode opératoire expérimental classique pour illustrer la force mesurée par les récepteurs de tension. Diverses neuromodulateurs peuvent être appliquées à la préparation de voir comment elle affecte le développement de la force et de la réponse neuronale. L&#39;un des aspects importants est la manière dont les réponses neurales sont traitées et intégrées dans le système nerveux central et leur incidence sur l&#39;activité des neurones moteurs. Les techniques que nous avons indiquées permettent de commencer à répondre à plus d&#39;informations sur la tension (sensoriel) nerf moteur fonction de circuit de neurone, <em>c&#39;est à dire</em> le signal dans une jambe intacte au ganglion et retourau muscle. </p><p class="jove_content"> Les procédures de coloration démontré sont la clé de la compréhension de la physiologie des neurones sensoriels qui innervent les organes proprioceptifs. Disposition anatomique des neurones basés sur la fonction et la taille de la soma sont similaires dans les différents organes chordotonaux dans les pattes de crabe. On ne sait pas si des dispositions neuronales similaires sont également présents dans d&#39;autres espèces ou d&#39;insectes crustacés. La combinaison des enregistrements physiologiques de cellules individuelles et la cartographie de la situation permet relations fonctionnelles de la structure directe. La préservation à long terme de la disposition anatomique avec <sub>CoCl2</sub> coloration et la fixation permet de faire des mesures de façon répétitive et évaluer l&#39;agencement structurel. </p><p class="jove_content"> Proprioception et la réception de tension des muscles squelettiques sont les modalités sensorielles qui permettent des comportements coordonnés et les réponses à l&#39;environnement externe et interne pour animaux articulés dans une variété de configuration du muscle squelettiques. L&#39;organe récepteur musculaire dans l&#39;abdomen de l&#39;écrevisse est une autre préparation bien documenté (voir le projet Ecrevisse; <a href="http://www.crawdad.cornell.edu/">http://www.crawdad.cornell.edu/</a> ) à des fins d&#39;enseignement de la proprioception avec seulement deux neurones par abdominale hémi-secteur <sup>23</sup> . Être capable d&#39;enregistrer à partir de neurones simples à faisceaux de nerfs sensoriels fournit plus de détails que l&#39;aide à comprendre les principes de base de la réception sensorielle. Ces préparations crustacés relativement simples permettent d&#39;aborder les aspects fondamentaux de la proprioception et la surveillance de la tension, avec la possibilité de déterminer les circuits neuronaux qui permettent l&#39;intégration centrale d&#39;entrées proprioceptives et autres sensoriels <sup>9-12, 32, 33.</sup> </p>

<p class="jove_content"> La proprioception est la sensation de la position des membres et le mouvement qui permet le comportement moteur coordonnée. Propriocepteurs sont constitués de la position (statique) et le mouvement des récepteurs (kinesthésiques). Chez les insectes et les crustacés, les organes chordotonaux sont les structures qui fournissent ces informations à la CNS <sup>1.</sup> Pas tous les organes chordotonaux couvrent un joint, mais ils peuvent toujours surveiller les mouvements des articulations en raison de leur attachement sur les apodèmes (tendon comme structures) qui couvrent la commune et se déplacent en association avec le muscle squelettique et joint d&#39;articulation. Pattes de crabe ont six articulations, ayant chacun un ou deux organes chordotonaux <sup>2.</sup> Typiquement, un organe chordotonal a 60-100 ou plusieurs neurones sensoriels intégrés au sein d&#39;une bande élastique, les neurones qui signalent position commune statique, la direction et la vitesse de déplacement <sup>3-6.</sup> L&#39;entrée des organes chordotonaux à chaque commune et de la jambe est ensuite traitées de manière centralisée permettant des mouvements coordonnés par l&#39;animal. </p><p class="jove_content"&gt; Les forces qui produisent des muscles de la jambe lors des contractions isométriques et isotoniques sont détectés par des récepteurs de tension associés aux fibres musculaires et leurs attachements à apodemes7-9. Dans les protocoles de crustacés de jambe de marche qui suivent, nous présentons une méthodologie pour les enregistrements de neurones sensoriels primaires qui surveillent la proprioception et les neurones qui répondent à des forces engendrées par les fibres musculaires. Une technique d&#39;activation de mouvements de la jambe et la quantification de génération de force est également présentée, ainsi que des techniques anatomiques qui peuvent être utilisés pour caractériser l&#39;agencement de ces structures du système nerveux périphérique. </p><p class="jove_content"> Les procédures démontré ci-dessous permettent l&#39;analyse structurale et fonctionnelle des neurones qui innervent les deux types de récepteurs par rapport à leur emplacement sur un brin élastique et chordotonal apodeme. A titre d&#39;illustration, on utilise la propodite-dactylopodite (PD) d&#39;organe chordotonal, l&#39;organe qui s&#39;étend sur la plus segment distal de la patte de crabe <sup>3.</sup>Bien que les études électrophysiologiques détaillées ont commencé dans les années 1930 et sont toujours en cours aujourd&#39;hui, certains aspects sont devenus connus sur les liens segmentaires de propriocepteurs dans les différentes articulations et leurs rôles dans le contrôle coordonné de muscles10-16. Établir la relation structure-fonction entre les organes, les muscles et proprioceptives, le système nerveux en outre aider à définir ces rôles. Par exemple, l&#39;étiquetage du soma et terminaisons distales des neurones de tension insérés dans le apodeme va révéler leur emplacement par rapport aux fibres musculaires <sup>8,17-21.</sup> </p><p class="jove_content"> Nous présentons trois techniques de coloration pour les jambes crustacés qui peuvent être utilisés dans la recherche ou des laboratoires universitaires. Coloration au bleu de méthylène donne un contraste adapté pour les muscles et les nerfs et est recommandé comme une technique simple pour les élèves à apprendre l&#39;anatomie. Les laboratoires qui ont des configurations de microscopie de fluorescence peuvent accomplir coloration neuronale plus sélective en exposant brièvement le nerfs vers le colorant vital 4-di-2-ASP. La troisième alternative est CoCl <sub>2</sub> remblai, qui colore et résout les neurones, et ne nécessite pas l&#39;imagerie de fluorescence. Bien qu&#39;il soit le travail et de temps, ce processus de coloration donne un contraste élevé et une spécificité pour les nerfs qui sont remplis. Ensemble, ces techniques peuvent être utilisées pour comparer différents organes chordotonaux, non seulement au sein d&#39;une branche ou entre membres, mais aussi parmi les autres espèces de crustacés et d&#39;insectes <sup>20-22.</sup> Crabes bleus <em>(C. sapidus)</em> utilisés dans les enregistrements physiologiques et pour la coloration anatomique sont disponibles tout autour de la frontière du Sud et du Sud-Est des États-Unis. Cette espèce sert un représentant des arrangements chordotonaux et tension nerveuses dans la plupart des crabes. Laboratoires sur la côte ouest préfèrent utiliser beaucoup plus grand crabe dormeur <em>(Cancer magister)</em> pour ces expériences. </p>

<table><tbody><tr><td>Sylgard</td><td>Dow Corning</td><td>182 silicone kit</td><td></td></tr><tr><td>NaCl</td><td>Sigma-Aldrich</td><td>S7653</td><td></td></tr><tr><td>KCl</td><td>Sigma-Aldrich</td><td>P9333</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma-Aldrich</td><td>C5670</td><td></td></tr><tr><td>HEPES acid</td><td>Sigma</td><td>3375</td><td>Free acid, crystalline</td></tr><tr><td>HEPES base</td><td>Sigma</td><td></td><td></td></tr><tr><td>D-Glucose</td><td>Sigma</td><td>G7021</td><td></td></tr><tr><td>MgSO&lt;sub&gt;4&lt;/sub&gt;&amp;bull;7H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma</td><td>M2643</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;&amp;bull;10H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma</td><td>246980</td><td></td></tr><tr><td>Bouin&amp;rsquo;s solution fixative</td><td>Sigma</td><td>HT10-1-32</td><td>Caution: Hazardous material (Special shipping cost required)</td></tr><tr><td>CoCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma</td><td></td><td>Caution: Hazardous material. Please follow proper disposal according to local and federal regulations.</td></tr><tr><td>Methylene blue chloride</td><td>Matheson Co., Inc</td><td>Basic Blue 9, C.I. 52015</td><td></td></tr><tr><td>4-Di-2-ASP</td><td>Molecular Probes</td><td></td><td>4-(4-diethylaminostyryl)-N-methylpyridinium iodide</td></tr><tr><td>Bleach</td><td>Sigma-Aldrich</td><td></td><td>To chloride silver wire</td></tr><tr><td>NaOH</td><td>Sigma-Aldrich</td><td>221465</td><td>To adjust pH</td></tr><tr><td>HCl</td><td>Sigma-Aldrich</td><td>H1758</td><td>To adjust pH</td></tr><tr><td></td><td></td><td></td><td></td></tr><tr><td>Materials</td><td></td><td></td><td></td></tr><tr><td>Dissecting tools</td><td>World Precision Instruments</td><td>assortment</td><td></td></tr><tr><td>Intracellular electrode probe</td><td></td><td></td><td></td></tr><tr><td>Faraday cage</td><td></td><td></td><td></td></tr><tr><td>Insect Pins</td><td>Fine Science Tools, Inc</td><td>26001-60</td><td></td></tr><tr><td>Dissecting microscope (100X)</td><td></td><td></td><td></td></tr><tr><td>Fiber optic lamp</td><td></td><td></td><td></td></tr><tr><td>Small adjustable mirror</td><td></td><td></td><td>To direct light beam toward the preparation.</td></tr><tr><td>Glass electrodes</td><td>Sigma-Aldrich</td><td>CLS7095B5X</td><td>Box of 200, suction electrodes</td></tr><tr><td>Micromanipulator</td><td>World Precision Instruments</td><td>MD4-M3-R</td><td>Can fix for base or on a metal rod</td></tr><tr><td>Raised preparation stand</td><td></td><td></td><td></td></tr><tr><td>Silver wire (10/1,000 inch)</td><td>A-M Systems</td><td>782500</td><td></td></tr><tr><td>Computer</td><td>Any company</td><td></td><td></td></tr><tr><td>AC/DC differential amplifier</td><td>A-M Systems</td><td>Model 3000</td><td></td></tr><tr><td>PowerLab 26T</td><td>AD Instruments</td><td>27T</td><td></td></tr><tr><td>Force transducer</td><td>AD Instruments</td><td>0-50g</td><td>MLTF050/ST</td></tr><tr><td>Head stage</td><td>AD Instruments</td><td></td><td>Comes with AC/DC amplifier</td></tr><tr><td>LabChart7</td><td>AD Instruments</td><td></td><td></td></tr><tr><td>Electrical leads</td><td>Any company</td><td></td><td></td></tr><tr><td>Glass tools</td><td>Make yourself</td><td></td><td>For manipulating nerves</td></tr><tr><td>Cable and connectors</td><td>Any company</td><td></td><td></td></tr><tr><td>Pipettes with bulbs</td><td>Fisher Scientific</td><td>13-711-7</td><td>Box of 500</td></tr><tr><td>Beakers</td><td>Any company</td><td></td><td></td></tr><tr><td>Wax or modeling clay</td><td>Any company or local stores</td><td></td><td></td></tr><tr><td>Stimulator</td><td>Grass Instruments</td><td>SD9 or S88</td><td></td></tr><tr><td>Plastic tip for suction electrode</td><td>Local hardware store (Watt&amp;rsquo;s brand)</td><td>&amp;frac14; inch OD x 0.170 inch ID</td><td>Cut in small pieces. Pull out over a flame and cut back the tip to the correct size</td></tr></tbody></table>

proprioception and tension receptors in crab limbs: student laboratory exercises

<p class="jove_content"> Le principal objectif de ces procédures est de démontrer à des fins d&#39;enseignement et de recherche comment enregistrer l&#39;activité des neurones sensoriels primaires responsables de la proprioception vivre comme ils détectent la position commune et le mouvement, et la tension musculaire. L&#39;activité électrique de propriocepteurs crustacés et les récepteurs de tension est enregistrée par l&#39;instrumentation de base neurophysiologique, et un transducteur est utilisé pour mesurer simultanément la force générée par la stimulation d&#39;un nerf moteur. En outre, nous démontrons comment colorer les neurones pour une évaluation rapide de leur disposition anatomique ou pour la fixation permanente. La coloration révèle organisation anatomique qui est représentative de la plupart des organes chordotonaux en crustacés. En comparant les réponses nerveuses de la tension aux réponses proprioceptives est un outil d&#39;enseignement efficace dans la détermination de la façon dont ces neurones sensoriels sont définies fonctionnellement et la façon dont l&#39;anatomie est corrélée à la fonction. Trois techniques de colorationsont présentés permettant aux chercheurs et enseignants de choisir une méthode qui est idéal pour son laboratoire. </p>

<p class="jove_content"> Lorsque l&#39;organe est étiré par PD s&#39;étendant complètement le joint, l&#39;activité dans le nerf PD est robuste au cours du mouvement comme indiqué pour la première seconde <strong>de la figure 10.</strong> Certaine activité demeure alors qu&#39;il est encore maintenu dans la position ouverte. Cette activité est dans les neurones sensibles à la position statique (deuxième moitié de l&#39;enregistrement représenté sur <strong>la figure 10).</strong> Mouvement évoque une réponse pendant le déplacement et le tir est surtout présent lors de l&#39;étirement du brin chordotonal <strong>(figure 11).</strong> </p><p class="jove_content"> Une analyse plus poussée des pointes peut être facilement approchée par le tri des amplitudes relatives. C&#39;est une approche de démontrer les différentes populations de neurones sensoriels étant recrutés pour des postes ou des types de mouvements <sup>5.</sup> Amplitudes typiques vont de 0,25 à 1,5 mV, mais ces valeurs sont fonction de la résistance <em>(par exemple</em> l&#39;étanchéité) du joint d&#39;étanchéité de l&#39;électrode d&#39;aspiration. Fréquence des pics de til différentes gammes de taille peut également être représentée graphiquement pour l&#39;analyse. </p><p class="jove_content"> Forces produites par le muscle de l&#39;ouvre par rapport à la fréquence de stimulation peuvent être comparés en superposant les traces tension-temps respectives au-dessus de l&#39;autre <strong>(figures 13A</strong> et <strong>B).</strong> Ceci peut également être effectué pour chaque position de joint au niveau de chaque fréquence de la stimulation donnée. Activité du nerf de tension peut alors être corrélée avec la quantité de force par rapport générés à chaque fréquence de stimulation, et pour chaque position de joint. Comme dans le nerf de la PD, de diverses amplitudes de pointes sont vus en réponse à la contraction du muscle d&#39;ouverture <strong>(Figure 13C).</strong> </p><p class="jove_content"> Disposition anatomique des neurones dans la jambe de marche est clairement observée avec coloration au bleu de méthylène <strong>(figure 14).</strong> Notez le brin et la tension chordotonal neurone élastique qui est proche de la apodeme. Plusieurs corps cellulaires avec des diamètres différents d&#39;uned emplacements spécifiques sont également visibles sur cette figure. Tout le cours du nerf de tension et civière nerf moteur sont présentées dans <strong>la figure 15.</strong> Neurones du nerf de PD sont présentés avec un contraste plus élevé en utilisant 4-di-2-ASP <strong>(Figure 16)</strong> et CoCl <sub>2</sub> <strong>(Figure 17)</strong> remblai techniques. À fort grossissement les terminaisons sensorielles peuvent être vus à l&#39;intérieur des scolopales soutien <strong>(figures 16B)</strong> <sup>21,22,26.</sup> </p><p class="jove_content" fo:keep-together.within-page="always"><img alt="Figure 10" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig10.jpg" width="500px" /><br /> <strong>Figure 10. Déplacez et maintenez à 0 °.</strong> Les neurones dynamiques sont robustes en feu pendant le mouvement et les pointes de neurones sensibles statiques sont présents alors que le joint est maintenu ouvert. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig10highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image &lt;</a>/ A&gt;. </p><p class="jove_content" fo:keep-together.within-page="always"><img alt="Figure 11" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig11.jpg" width="500px" /><br /> <strong>Figure 11. Rapide ouvert et la fermeture de flexion complète à la position étendue (90-0 °).</strong> <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig11highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image</a> . </p><p class="jove_content" fo:keep-together.within-page="always"><img alt="Figure 12" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig12.jpg" width="500px" /><br /> <strong>Figure 12. Pointes extracellulaires enregistrées depuis le nerf de PD.</strong> La commune est en pleine extension, puis rapidement déplacé vers un ½ position fléchie et tenait toujours. Remarquez l&#39;activité pendant le mouvement et diminution de l&#39;activité quand statique. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig12highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;ima</a>ge. </p><p class="jove_content" fo:keep-together.within-page="always"><img alt="Figure 13" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig13.jpg" width="500px" /><br /> <strong>Figure 13. Les forces qui sont développées par rapport à l&#39;articulation entièrement fléchies et stimulés à différentes fréquences. (A)</strong> de tension à temps des traces provenant du transducteur de force sont représentés à chaque fréquence de stimulation. <strong>(B)</strong> Les traces du groupe A sont superposées dans des couleurs différentes pour faciliter la comparaison. <strong>(C)</strong> Tension-temps des traces de l&#39;activité électrique enregistrée par le nerf de la tension lorsque le nerf moteur a été stimulée à 80 Hz. Notez le motif régulier des artefacts de stimulus par rapport à l&#39;activité neuronale. En outre, notez les différentes amplitudes des réponses neuronales. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig13highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image</a> . </p><p class="jove_content" fo:keep-together.wSEIN page = &quot;always&quot;&gt; <img alt="Figure 14" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig14.jpg" width="500px" /><br /> <strong>Figure 14. Méthylène bleuissement de la préparation de la jambe de marche.</strong> Somas individuelles sont présentées avec leurs terminaisons sensorielles projeter dans le brin élastique. Près de la apodeme un neurone de la tension est affichée. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig14highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image</a> . </p><p class="jove_content" fo:keep-together.within-page="always"><img alt="Figure 15" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig15.jpg" width="500px" /><br /> <strong>Figure 15. Le nerf de la tension résultant de l&#39;extrémité distale (flèches rouges) et de rejoindre le nerf moteur (flèche verte).</strong> <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig15highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image</a> . </p><p class="jove_content" fo:keep-together.within-page = &quot;always&quot;&gt; <img alt="Figure 16" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig16.jpg" width="500px" /><br /> <strong>Figure 16. (A) Un remblai du nerf PD en <em>Cancer magister</em> avec 4 Di-2-ASP. (B)</strong> grossissement supérieur de terminaisons sensorielles. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig16highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image</a> . </p><p class="jove_content" fo:keep-together.within-page="always"><img alt="Figure 17" fo:content-width="5in" src="/files/ftp_upload/51050/51050fig17.jpg" width="500px" /><br /> <strong>Figure 17. Les neurones qui ont été remplis avec <sub>CoCl2</sub> et traitées (A).</strong> Contour tracé de la préparation colorée montré <strong>(B).</strong> <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51050/51050fig17highres.jpg" target="_blank">Cliquez ici pour agrandir l&#39;image</a> . </p><table border="0" cellpadding="0" cellspacING = &quot;0&quot; width = &quot;392&quot;&gt; <colgroup><col /><col /></colgroup><tbody><tr height="21"><td height="21" style="height:21px;width:235px;"> <strong>Saline</strong> </td><td style="width:157px;"> <strong>g / L</strong> </td></tr><tr height="20"><td height="20" style="height:20px;width:235px;"> NaCl </td><td style="width:157px;"> 27.29 </td></tr><tr height="20"><td height="20" style="height:20px;width:235px;"> KCl </td><td style="width:157px;"> 0,81 </td></tr><tr height="26"><td height="26" style="height:26px;width:235px;"> MgSO <sub>4</sub> 7H <sub>2</sub> O • </td><td style="width:157px;"> 4.81 </td></tr><tr height="26"><td height="26" style="height:26px;width:235px;"> CaCl <sub>2</sub> • 2H <sub>2</sub> O </td><td style="width:157px;"> 1,85 </td></tr><tr height="26"><td height="26" style="height:26px;width:235px;"> Na <sub>2</sub> SO <sub>4</sub> • 10H <sub>2</sub> O </td><td style="width:157px;"> 0,97 </td></tr><tr height=&quot;20&quot;&gt; <td height="20" style="height:20px;width:235px;"> Le dextrose (D-glucose) </td><td style="width:157px;"> 1.982 </td></tr><tr height="20"><td height="20" style="height:20px;width:235px;"> Acide HEPES </td><td style="width:157px;"> 0,476 </td></tr><tr height="20"><td height="20" style="height:20px;width:235px;"> HEPES sel </td><td style="width:157px;"> 2.08 </td></tr><tr height="40"><td height="40" style="height:40px;width:235px;"> Ajuster le pH à 8,1 avec NaOH ou HCl </td><td style="width:157px;"></td></tr></tbody></table><p> <strong>Tableau 1. Recettes pour saline de crabe.</strong> </p>

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Proprioception et récepteurs de tension dans les membres du crabe | Neurosciences | Vidéo

Proprioception and Tension Receptors in Crab Limbs: Student Laboratory Exercises

<p class="jove_content"> Techniques physiologiques et anatomiques sont démontrés pour traiter la fonction et la structure des propriocepteurs communes et des récepteurs de la tension musculaire dans les membres de marche de crustacés. </p>

Proprioception et tension récepteurs en crabe Membres: Exercices de laboratoire étudiant

The primary purpose of these procedures is to demonstrate for teaching and research purposes how to record the activity of living primary sensory neurons ...

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25.1K vues.  University of Kentucky.  Techniques physiologiques et anatomiques sont démontrés pour traiter la fonction et la structure des propriocepteurs communes et des récepteurs de la tension musculaire dans les membres de marche de crustacés. 

Vidéo: Proprioception and Tension Receptors in Crab Limbs: Student Laboratory Exercises

Lab Techniques

<h4>Measurement Accuracy</h4>
<p>The ability to repeat an experiment and get the same results, or <em>reproducibility</em>, is essential in scientific research. However, it&#8217;s impossible to repeat an experiment if you don&#8217;t know how you did it. Thus, scientists keep detailed records of their experiments in lab notebooks. These records include important information like the amount of each material used and descriptions of each step of the procedure.</p>
<p>Equipment, like balances and volumetric or graduated glassware, is used to measure solid and liquid compounds for experiments. The precision of each measurement is limited by the equipment used. Balances and other equipment with digital readouts automatically display values at the maximum precision that they can support. The precision of graduated glassware and rulers depends on the increment, which is the amount represented by the smallest distance between two marks.</p>
<p>The surface of most liquids curves upwards at the edges in glass containers. This type of curved liquid surface is called a concave meniscus. When the edges of the liquid curve down, it is called a convex meniscus. When measuring liquid volumes, the reference point for the top of the liquid is the bottom of a concave meniscus or the top of a convex meniscus. To accurately identify the position of the meniscus, liquid volumes are read by looking at the liquid&#8217;s surface from the side at eye-level. Looking at the liquid from above or below will cause the liquid surface level to appear higher or lower than it actually is.</p>
<p>When the reference point of the meniscus touches a mark on graduated or volumetric glassware, the glassware is holding the volume defined for that mark. Volumetric glassware is designed to measure a specific volume, so it only has one mark. Graduated glassware is designed to measure a range of volumes, so it has many marks, or <em>graduations</em>, which are labeled at regular intervals. Both graduated and volumetric glassware may have additional manufacturer-provided information about their precision.</p>
<h4>Calibration and Uncertainty</h4>
<p>Manufacturers calibrate equipment to ensure that the measurements are accurate to within a specified range of uncertainty. For example, a high-precision analytical balance may read out to four decimal places (0.0000 g) with an uncertainty of &#177; 0.0001 g. A reading of 0.0345 g indicates that the true value is between 0.0344 g and 0.0346 g.</p>
<p>Glassware typically has its measurement uncertainty printed on it. To accurately record volume measurements, you must consider both the increment and the uncertainty. For example, a precise volume measurement in a 100 mL graduated cylinder with 1 mL increments and an uncertainty of &#177; 0.5 mL would be recorded to the tenths place (000.0 mL &#177; 0.5 mL). If the reference point of the meniscus falls between two marks, you should estimate a value for the tenths place; otherwise, leave it as 0. Since temperature affects volume, the temperature for which the glassware is calibrated will be printed on it.</p>
<p>Glassware is calibrated either <em>to contain</em> (TC) or <em>to deliver</em> (TD). TC glassware holds the specified volume of liquid when it is filled to the mark, but a small amount of liquid will be left behind when it is poured into another container. Solutions are often prepared in TC glassware because the accuracy of the solution volume affects the accuracy of the concentration. Volumetric flasks are typically calibrated to contain.</p>
<p>TD glassware holds a little more than the amount of liquid specified when it is filled to the mark, but it dispenses only the specified volume. Thus, TD glassware should not be emptied completely when dispensing liquids. This type of glassware is useful for transferring a precise volume of liquid to another container. Both graduated and volumetric pipettes are typically calibrated to deliver.</p>
<p>Unless otherwise specified, the uncertainty of a number is assumed to be on the scale of the last digit. Thus, it&#8217;s particularly important to report the uncertainty of a measurement if the uncertainty is on a larger scale. For rulers and graduated glassware without a known uncertainty, the uncertainty is estimated as half of the smallest increment. The uncertain digit is based on where the meniscus falls between two tick marks.</p>
<h4>Significant Figures</h4>
<p>Significant figures are the numbers in a value that are <em>meaningful</em>, or essential for expressing that value with the appropriate precision. All numbers other than leading zeroes (<strong>0.00</strong>1), trailing zeroes (1,<strong>000</strong>), or scientific notation multipliers (<strong>10</strong><sup>x</sup>) are always significant.</p>
<p>Leading zeroes are never significant because they can be removed by rewriting the number either in scientific notation or, if it is an SI unit, in smaller units. For example, there are only three significant figures in the value 0.00123 m because it can be rewritten as either 1.23 &#215; 10<sup>-3</sup> m or 1.23 mm without losing any information. Note that the scaling factor between different multiples of the same SI unit does <em>not</em> affect the number of significant figures.</p>
<p>Trailing zeroes are significant when they are before or after a decimal point. For example, the measurement 100.110 mL has six significant figures and 100.0 mL has four. Trailing zeroes in a number written without a decimal point are assumed to be insignificant unless they are marked otherwise. There are several different conventions for marking significant zeroes in those cases, but to avoid ambiguity it is advisable to rewrite those values in scientific notation. If the measurement is in SI units, use larger units.</p>
<p>The precision of a measurement limits the precision of any values calculated from it. A calculated value has the same number of significant figures as the <em>least</em> precise measurement or value used in its calculation. If the result has too many significant figures, it is rounded to the appropriate precision. If the result has too few significant figures, it is extended with significant trailing zeroes to preserve the precision. The significant figures of experimentally derived values, like molar mass, density, or some unit conversion factors, must also be considered when they are used in calculations.</p>
<p>The number of significant figures in a calculated value is <em>not</em> limited by physical or mathematical constants in formulas or exact numbers, like the number of data points acquired in an experiment. For example, the formula for calculating the volume of a sphere is V = 4/3&#960;r<sup>3</sup>. The number of significant figures in the calculated volume is <em>only</em> affected by the number of significant figures in the radius measurement <strong>r</strong>. 4/3&#8201; and &#960; are constants, and <sup>3</sup> is simply notation for a mathematical operation.</p>
<p>Defined conversion factors are also treated as constants. For instance, the inch is defined as exactly 25.4 millimeters; therefore, the number of significant figures of the converted value depends only on the original measurement. Always check whether the conversion factor is exactly defined or an experimental value when converting between units.</p>
<p>For simple addition and subtraction of measurements, we use significance arithmetic to determine the number of significant figures. In this case, the answer has as many decimal places as the measurement with the fewest decimal places <em>regardless of the number of significant figures</em>. Thus, 15,643.7 mL + 0.613 mL = 15,644.3 mL.</p>
<p>For multi-step calculations or complex equations that you break into smaller parts to solve, you should keep at least one or two insignificant figures on the intermediate values. For example, if you calculate the values of the numerator and denominator of a fraction separately before dividing them, you should retain the insignificant figures of the numerator and denominator when you divide them. This minimizes <em>rounding error</em>, which is the difference from the number you would get if you entered the entire formula into your calculator at once. If you write down these intermediate values, you should note which digits are insignificant.</p>
<h4>References</h4>
<p>Harris, D.C. (2015). <em>Quantitative Chemical Analysis</em>. New York, NY: W.H. Freeman and Company.</p>

Accuracy, Precision, Uncertainty, and Significant Figures - Concept

Techniques de laboratoire

Measurement Accuracy
The ability to repeat an experiment and get the same results, or reproducibility, is essential in scientific research. However, ...

Enseignement

JoVE Lab Manual

Chimie

Extraction

<p><strong>Extraction</strong></p>
<p>Extraction is a common technique used in organic chemistry to isolate a target compound. In the extraction process, a solute is transferred from one phase to another to separate it from unreacted starting materials or impurities. Extraction is also used to facilitate the isolation of a solute from a reaction solvent that is difficult to remove by evaporation, such as a solvent with a high boiling point.<span style="color: rgb(0, 0, 0); font-family: Roboto, RobotoDraft, Helvetica, Arial, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: pre-wrap; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;"> </span>Generally, there are three types of extractions. First, in solid-liquid extraction, the solute is transferred from a solid phase to a liquid phase. In liquid-liquid extraction, a solute is transferred from one liquid to another. In acid-base extraction, a solute is transformed into an ionic compound and transferred from an organic phase to an aqueous phase. A common example of extraction is the brewing coffee or tea. The solid phase, which contains the caffeine, plant flavors, and odors, is extracted by the hot water into the liquid phase.</p>
<p><strong>Liquid-Liquid Extraction</strong></p>
<p>A liquid-liquid extraction either transfers an organic compound that is dissolved in an aqueous phase to an organic solvent, or it is used to transfer unreacted reactants, salts, and other water-soluble impurities to the aqueous phase while leaving the organic compound of interest in the organic phase. Immiscible liquids are liquids that never form a homogenous solution, even when thoroughly mixed. Instead, immiscible liquids separate into different phases, like oil and water.</p>
<p>A liquid-liquid extraction transfers an organic compound that is dissolved in an aqueous phase to an organic solvent. To perform a liquid-liquid extraction, first, the aqueous solution containing the solute is added to a separatory funnel. Then, a non-water-soluble organic solvent is added to the separatory funnel. When the contents of the funnel are mixed well, the organic compound partitions into the organic phase based on its higher solubility in the organic phase than the aqueous phase.</p>
<p>Since the two solvents are immiscible, the two liquids form discrete layers, with the dense liquid on the bottom and the less dense liquid on the top. Once the two phases settle back into two layers, they are separated by opening the stopcock at the bottom of the separatory funnel and allowing one layer to flow out. The liquid that had the solute removed is called the raffinate, while the liquid that gained the solute is called the extract.</p>
<p>The organic compound is partitioned between the two layers based on its solubility in each phase. Equilibrium is reached when the chemical potential of the solute is the same in the two phases. The partition coefficient for a solute, K, is the ratio of the concentration of the sample in the organic layer divided by the concentration in the aqueous phase. The partition coefficient is a constant dependent on both the solute and the pair of solvents used in the extraction. The partition coefficient is an expression of preference of the solute for each of the two solvents. Solutes with a large partition coefficient have a higher tendency to be extracted into the organic solvent layer. Solutes with small partition coefficients prefer to transition into the aqueous phase.</p>
<p>Determining which solvent pair to use for a liquid-liquid extraction is a vital step. Consider the following when choosing which solvents to use: First, the solute must be more soluble in the solvent than in water. Therefore, knowing the partition coefficient of the solute in a potential solvent pair is necessary. Second, the solvent-pair must be immiscible in water and not form a homogeneous solution when mixed. Third, the solvents must be inert and not react with the solute. The solvent should also be volatile so that it can be removed from the solute easily. The water-immiscible organic solvent generally possesses a non-polar or low polarity.</p>
<p>It is also critical to know the densities of the solvents to determine the identities of the top and bottom layers. Most organic liquids have a lower density than water, with the exception of chlorinated organic solvents, and will settle to the bottom of the separatory funnel.</p>
<p><strong>Acid-Base Extraction</strong></p>
<p>Acid-base extraction is a type of liquid-liquid extraction that separates organic compounds based on their acid-base properties. If a solute is an acid or base, its charge changes as the pH is changed. Generally, most organic compounds are neutral, and therefore more soluble in organic solvents than they are in water. However, if the organic compound becomes ionic, then it becomes more soluble in water. This is useful in extracting an organic acid or base compound from an organic phase to an aqueous phase.</p>
<p>Acid-base extraction harnesses this property by transforming the solute into its water-soluble salt form, thereby changing its solubility. The solubility of the organic compound and its salt must be dramatically different in order for the technique to be effective.</p>
<p>For example, consider a mixture containing an organic carboxylic acid, an amine, and a neutral compound. Carboxylic acids consisting of six carbons or more are insoluble in water and entirely soluble in organic solvents. However, their conjugate bases (an ionic compound) are water-soluble and insoluble in organic solvents. An amine consisting of at least seven carbons is insoluble in water but soluble in organic solvents. The conjugate acid of that amine (an ionic compound) is water-soluble and insoluble in organic solvents.</p>
<p>When reacted with a base, the carboxylic acid is neutralized to its salt form. The other compounds in the mixture remain neutral. Once the carboxylic acid is transformed into a salt, it will partition to the aqueous phase, while the neutral compounds remain in the organic phase.</p>
<p>Acid-base extraction is also used to separate two weak acids or two weak bases with a significant difference in their pK<sub>a</sub>. In the case of the acids, the relatively stronger acid, having a small pKa value, is neutralized to a salt using a weak base. The weak base does not efficiently react with the weaker acid, and only the stronger acid is transformed to a salt. Then, the salt is extracted into the aqueous phase during extraction. The process follows similarly for weak bases, where the relatively stronger base is neutralized to a salt using a weak acid.</p>
<p><strong>References</strong></p>
<ol>
	<li style="font-size:17px">Harris, D.C. (2015). <em>Quantitative Chemical Analysis.</em> New York, NY: W.H. Freeman and Company.</li>
</ol>

Extraction: Liquid-Liquid and Acid-Base Extraction - Concept

Extraction
Extraction is a common technique used in organic chemistry to isolate a target compound. In the extraction process, a solute is transferred ...

Scientific Measurement and Lab Skills

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Preparation of the Laboratory<button class="expand">Expand</button>
	<p><em>Here, we show the laboratory preparation for 10 students working individually, with some excess. Please adjust quantities as needed.</em></p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Prepare a 1.5 x 10<sup>-5</sup> M erythrosin B red dye solution. To prepare 500 mL of this solution, weigh 0.0066 g of erythrosin B on an analytical balance.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Transfer the erythrosin B to a 250-mL Erlenmeyer flask. Then, measure 200 mL of deionized water and add it to the flask. Place a magnetic stir bar in the flask, set the flask on a stir plate, and mix the solution until it appears homogeneous.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Use a funnel to pour the solution into a 500-mL volumetric flask, and carefully fill the flask to the line using deionized water. Seal the top of the flask with paraffin film and invert it several times until the solution is well-mixed.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Label a 500-mL squeeze bottle with the concentration and transfer the solution into the bottle. Store the bottle on a mat in the hood.<strong> Note: </strong>Take significant figures into account.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Place acetone in an area so that students have access to it during the lab. <strong>Note: </strong>Each student will need about 40 mL.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Set weigh boats, scoops, and a container of sand next to a balance. <strong>Note: </strong>Each student will need about 3 g.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Place an organic waste container in a central hood.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Set out the following glassware and equipment at each student lab station (we suggest students work independently during this lab):
		<table align="center" style="border-collapse: collapse; font-size: 17px; line-height: 24px;">
			<tbody>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;50-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;100-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;250-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;400-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;600-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;500-mL filter flask</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;B&#252;chner funnel</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;10-mL graduated cylinder</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Watch glass</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;5-mL volumetric pipette</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;10-mL volumetric pipette</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;10-mL capacity pipetter</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;10-mL volumetric flask</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;String (18 in)</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Silicone vacuum tubing (18 in)</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;12-in ruler</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Rubber adapter</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Rubber stopper</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Glass stirring rod</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Rubber policeman</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Disposable pipette</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Bottle of deionized water</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Lab mat</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Box of filter papers (1 filter paper per student)</td>
				</tr>
			</tbody>
		</table>
		</div>
		</li>
	</ul>
	</li>
</ol>

Two-Dimensional Graphs, Curve Fitting, and Standard Deviation - Prep

Mesure scientifique et compétences de laboratoire

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Preparation of the LaboratoryExpand
	Here, we show the laboratory preparation for 10 students ...

Lab Manual Sub Articles

Energy Dynamics

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Caterpillar Energy Dynamics
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">NOTE: In this lab you will grow caterpillars in conditions with and without food to examine the transfer of biomass in a typical trophic system.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Weigh and record the wet mass of enough leaves of cabbage to line the bottom of a plastic tub.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Then, collect two batches of five caterpillars from their cabbage habitat, and weigh and record the wet mass of each batch separately in individual weigh boats. Make sure to tare the balance before each measurement. HYPOTHESES: The experimental hypothesis is that only a fraction of energy will be transferred between the trophic levels of the cabbage and the caterpillars and a significant amount will be lost as waste and heat energy. The null hypothesis is that there will be no significant difference between the energy input from the cabbage, and the obtained energy stored as biomass in the caterpillars.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Place the weighed cabbage and five caterpillars in a plastic tub lined with damp paper towels, leaving the lid slightly cracked open for ventilation, but not wide enough for the animals to escape.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Place the other five caterpillars in a second clean container prepared the same way, but with no cabbage.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">After three days, transfer the caterpillars to new weigh boats, and weigh and record the final wet mass of both groups of caterpillars and the cabbage.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Then place the caterpillar waste, or frass, and cabbage into two separate dishes, and put both dishes into a 37 &#176;C incubator to dry for 48 hours.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">Euthanize the weighed caterpillars by putting them into a minus 20 &#176;C freezer for 24 hours.
</div></li><li data-sub-note-item="1-9"><div class="lab-step">Then, transfer the dishes to a 37 &#176;C incubator for 48 hours.
</div></li><li data-sub-note-item="1-10"><div class="lab-step">After drying, weigh and record the dry mass of the uneaten cabbage, the two groups of caterpillars, and the frass, and use these data to calculate the percent biomass of the caterpillars.
</div></li><li data-sub-note-item="1-11"><div class="lab-step">Finally, discard all of the dried organisms and plates into the hazardous waste bin, and wipe down your workspace with 70% ethanol.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">Take a look at the data you collected. Ensure the initial wet mass, the final wet mass, and the final dry mass columns are accurately filled out in your table. <a href="https://www-jove-com.remotexs.ntu.edu.sg/CDNSource/lm/labs/13/Table_1_Energy_Dynamics.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 1</a>
</div></li><li data-sub-note-item="2-2"><div class="lab-step">NOTE: Remember an object&#39;s biomass is equal to its dry mass. Therefore, percent biomass for each group is the final dry mass divided by the final wet mass times 100. For example, obtain the percent biomass of the cabbage by dividing the final dry mass by the final wet mass and multiplying by 100. This means that approximately 15% of the cabbage&#39;s total weight is biomass.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">After this, estimate the initial biomass of the cabbage and caterpillars by multiplying the percent biomass by the initial wet mass, and put the values in this new table. NOTE: Remember, biomass equals dry mass. Therefore, the final dry mass is equal to the final biomass of each group.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">To calculate the approximate initial and final energy in the form of kilocalories within the cabbage, caterpillars, and frass, multiply the biomass values recorded in your table by the conversions, and record the calculated values in the table. <a href="https://www-jove-com.remotexs.ntu.edu.sg/CDNSource/lm/labs/13/Table_2_Energy_Dynamics.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 2</a>
</div></li><li data-sub-note-item="2-5"><div class="lab-step">After this, subtract the initial energy from the final energy to obtain the change in energy for each group.
</div></li><li data-sub-note-item="2-6"><div class="lab-step">NOTE: The negative sign denotes loss in energy, and positive indicates gain.
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Using your data table, calculate the energy in kilocalories that the fed caterpillars lost to respiration. The formula is the energy gained from cabbage, which is the positive of the energy lost by cabbage, minus the biomass gained from cabbage, minus the energy lost via frass. <a href="https://www-jove-com.remotexs.ntu.edu.sg/CDNSource/lm/labs/13/Table_3_Energy_Dynamics.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 3</a>
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Then, repeat the same calculation for the unfed group of caterpillars. Make another column in the table and note this down.
</div></li><li data-sub-note-item="2-9"><div class="lab-step">Finally, add up all of the energy gained via biomass and cabbage consumption, and the energy lost via frass and respiration for each group of caterpillars. NOTE: For both groups of caterpillars the net energy is zero, meaning that this experiment obeyed the first law of thermodynamics.
</div></li></ul></li></ol>

Studying Energy Dynamics and Productivity - Procedure

Dynamique de l’énergie

Caterpillar Energy Dynamics
ExpandNOTE: In this lab you will grow caterpillars in conditions with and without food to examine the transfer of biomass in a ...

Biologie

Ecologie

Animal Behavior

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Making Choice Chambers
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">Before beginning the experiments, use one of the Sharpies from the lab table to trace a line around the circumference of the bottom of both bottles. One line should be 1 cm from the base of the bottle and the other should be 1.5 cm from the base of the bottle.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Use a razor blade to make a small cut in each bottle at the mark. 
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Then, insert the scissors and carefully cut along the line until the bottoms of the bottles are removed completely.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Fit one bottle bottom into the other.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Tape the bottles together to make a secure chamber.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">Use the razor blade and scissors to poke a hole into the center of the chamber. 
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Take a piece of tape and fold the edge onto itself to make a tab and place the tape over the hole.  Note: The tab helps with easy removal and reattachment of the tape to the chamber.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">Use the Sharpie to label one side of the chamber A and the other side B.
</div></li><li data-sub-note-item="1-9"><div class="lab-step">Upon receiving the colony of <em>Drosophila</em>, perform a count to make sure there are 40 living individuals in the vial.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Geotaxis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">To perform a geotaxis assay, first attach a clean, empty bottle cap to each end of the choice chamber and turn the fly vial upside down onto its lid.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Open the tape flap in the center of the choice chamber.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Insert the funnel into the hole and tap all of the flies into the chamber. HYPOTHESES: The alternate hypothesis is that more flies will be moving against gravity, or up, regardless of the orientation of the choice chamber. Alternatively, if the flies are positively geotactic, then more flies will move down, or with gravity. The null hypothesis is that the flies will have no preference with regard to gravity and will move randomly within the chamber. 
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Once the <em>Drosophila</em> are in the chamber, close the tape flap, rotate the chamber so that it stands vertically with side A on the bottom, and start the timer.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Immediately, count the number of <em>Drosophila</em> that are moving up and the number that are moving down. Record these data for time point 0 in the table. 
</div></li><li data-sub-note-item="2-6"><div class="lab-step">After 30 seconds, rotate the chamber so that side B is on the bottom and count the number of <em>Drosophila</em> that are moving up or down. Record these data for time point 30 in the table.
</div></li><li data-sub-note-item="2-7"><div class="lab-step">After 60 seconds, rotate the chamber so that side A is on the bottom again and record the number of moving flies for time point 60.  <a href="https://www-jove-com.remotexs.ntu.edu.sg/CDNSource/lm/labs/15/Table_1_Animal_behavior.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 1</a>
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Hold the chamber over the fly vial and carefully open the cap to return all of the <em>Drosophila</em> back to their empty vial. 
</div></li></ul></li><li data-note-item="3" data-parent-collapse="">Phototaxis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="3-1"><div class="lab-step">To perform a phototaxis analysis, first cover side A of the choice chamber with tin foil, taking care that the foil reaches to the exact center between the two sides. 
</div></li><li data-sub-note-item="3-2"><div class="lab-step">Ensure the caps are secured on both ends of the chamber.  HYPOTHESES: In this exercise, the alternative hypothesis is that more flies will be found in the light side of the choice chamber, if the flues are attracted to light, or on the dark side if they are repelled by light. The null hypothesis is that <em>Drosophila</em> will have no preference with regard to either stimulus. Therefore, equal numbers of flies will be found on either side of the choice chamber.
</div></li><li data-sub-note-item="3-3"><div class="lab-step">Open the tape flap in the center of the choice chamber, insert the funnel into the hole, and tap all 40 flies into the chamber as previously described.
</div></li><li data-sub-note-item="3-4"><div class="lab-step">Set the timer to sound an alarm at 10 minutes.
</div></li><li data-sub-note-item="3-5"><div class="lab-step">When the alarm sounds, stop the timer, and count the number of flies in the open side B of the chamber.
</div></li><li data-sub-note-item="3-6"><div class="lab-step">Subtract that number from the total number of flies added to the choice chamber to calculate the number of flies in the covered side A.
</div></li><li data-sub-note-item="3-7"><div class="lab-step">Record these data in the table for time point 10.  <a href="https://www-jove-com.remotexs.ntu.edu.sg/CDNSource/lm/labs/15/Table_2_Animal_behavior.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 2</a>
</div></li><li data-sub-note-item="3-8"><div class="lab-step">Carefully, return all of the flies back to their empty vial.
</div></li></ul></li><li data-note-item="4" data-parent-collapse="">Chemotaxis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="4-1"><div class="lab-step">HYPOTHESES: In this exercise, the alternative hypothesis is that more flies will be found on the side of the chamber with the apple cider vinegar if the flies are attracted to the odor. Or, if the flies are repelled by the vinegar, then more of them will be found on the side of the chamber presenting the odorless water. The null hypothesis is that <em>Drosophila</em> will have no preference with regard to either stimulus and will move randomly in the chamber.  Use an individual disposable plastic pipette to dispense two drops of the apple cider vinegar onto one cotton ball for side A of the chamber. 
</div></li><li data-sub-note-item="4-2"><div class="lab-step">Use an individual disposable plastic pipette to dispense two drops of the distilled water onto a cotton ball for side B of the chamber. 
</div></li><li data-sub-note-item="4-3"><div class="lab-step">Fold two pieces of tape over themselves to create individual pieces of double-sided tape and use the tape to attach each cotton ball to the inside of the single bottle cap.
</div></li><li data-sub-note-item="4-4"><div class="lab-step">Screw the bottle caps with the cotton balls onto their corresponding sides of the chamber.
</div></li><li data-sub-note-item="4-5"><div class="lab-step">Transfer all of the flies into the chamber and set the timer to sound an alarm after 10 minutes. 
</div></li><li data-sub-note-item="4-6"><div class="lab-step">When the alarm sounds, stop the timer and record the number of flies in each side of the chamber. <a href="https://www-jove-com.remotexs.ntu.edu.sg/CDNSource/lm/labs/15/Table_3_Animal_behavior.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 3</a>
</div></li><li data-sub-note-item="4-7"><div class="lab-step">At the end of the final experiment, funnel the flies into a morgue tube containing 70% ethanol. 
</div></li><li data-sub-note-item="4-8"><div class="lab-step">Dismantle the choice chambers for recycling.  NOTE: Since all of the chemicals used in these experiments are lab safe, the liquids can be disposed of down the sink, the chambers rinsed, and the solids can be thrown away in the trash. 
</div></li></ul></li><li data-note-item="5" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="5-1"><div class="lab-step">Gather all of the data collected for the geotaxis, phototaxis, and chemotaxis experiments.
</div></li><li data-sub-note-item="5-2"><div class="lab-step">Plot these values as bar graphs for different conditions and different time points.
</div></li><li data-sub-note-item="5-3"><div class="lab-step">Use these data to draw inferences about the behavior of <em>drosophila melanogaster</em>. 
</div></li></ul></li></ol>

Animal Behavior: Studying Taxis Behavior of Drosophila - Procedure

Comportement animal

Making Choice Chambers
ExpandBefore beginning the experiments, use one of the Sharpies from the lab table to trace a line around the circumference of the ...

Natural Selection

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Simulating Natural Selection
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">To prepare for the lab, set out workstations for each student pair containing 6 white, 6 black, and 13 gray 12 inch pipe cleaners.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Then, add 62 pipe cleaners in any color but black, white or gray, a roll of tape, and a pair of scissors.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Also, place one piece of black construction paper and one piece of white construction paper at each station.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Finally, print out tables so that there are enough for each set of partners in the class.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">To save materials for subsequent labs, inform students to save the materials and to avoid damaging them as much as possible.
</div></li></ul></li></ol>

Natural Selection: Calculating Fitness and Selection - Prep

Sélection naturelle

Simulating Natural Selection
ExpandTo prepare for the lab, set out workstations for each student pair containing 6 white, 6 black, and 13 gray 12 inch ...

Evolution

Scientific Method

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Demonstrating the Scientific Method with Tree Branches
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">Obtain branches containing a few dozen typical leaves from five different local tree species. The branches should represent a range of leaf and tree types. 
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Label each branch and leaf with their species name. 
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Distribute the branches to the students, so that each student has access to all five species. 
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Provide some background information about the environment from which each branch was collected. 
</div></li></ul></li></ol>

Scientific Method: Steps and Applications - Prep

Méthode scientifique

Demonstrating the Scientific Method with Tree Branches
ExpandObtain branches containing a few dozen typical leaves from five different local tree species. ...

Les bases

Measuring Biodiversity

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Quadrats and Transects Preparation
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">Start by tying a knot at the beginning, end and every 5 feet of six 20-foot pieces of rope.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Then, identify three outdoor areas near the classroom, each containing a variety of at least four plant species.  NOTE: Surprisingly, grassy areas often contain at least four plant species. Although most plants in these areas will be of a single grass species, there are usually many weeds, such as clovers or dandelions mixed in. Therefore, a well-kept grassy area without shade, a well-kept grassy area with shade, for example under a tree, and a weedy field could be used for the three different habitats that they students will be moving between.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Place two ropes parallel to each other within each of the habitats. It does not matter which direction the ropes face as long as the entire length of rope is within each area and a hula hoop can be placed on either side of the ropes within the habitat.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Finally, back in the lab set out enough plant identification guides for each student group to have at least one.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Also set out enough hula hoops so that each group has one to use as a sampling quadrat.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Diversity Lab Simulation Preparation
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">Before beginning the species accumulation curves and richness evenness activity, place 50 colored beads into one paper bag. The bag should contain 15 black beads, 10 purple beads, 8 red beads, 5 green beads, 3 blue beads, 3 yellow beads, 2 pink beads, 2 brown beads, 1 orange bead and 1 white bead.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Label this bag Community A.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Then, add five beads of each color to the second bag and mark this bag Community B.
</div></li></ul></li></ol>

Mesurer la biodiversité

Quadrats and Transects Preparation
ExpandStart by tying a knot at the beginning, end and every 5 feet of six 20-foot pieces of rope.
Then, identify three ...

Animal Diversity

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Form and Function of Crickets and Crayfish
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">This lab involves dissection of both crickets and crayfish. You will need one cricket and one crayfish for each pair of students. IMPORTANT: Purchase the largest crickets available and place them in the freezer the night before.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">On the day of the lab if they are frozen, allow the crickets to thaw for at least three hours before the dissections begin.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">While waiting for the crickets to thaw, melt dissecting wax in a microwave or on a hotplate until it is completely liquefied.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Fill enough Petri dishes to have one per student pair to around halfway. Allow these plates to harden at room temperature.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Next set out a dissecting tray, 12 pins, scissors and a needle probe for each pair of students.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">Also set up a few dissecting microscopes around the room and turn them on. NOTE: Generally, one microscope for four students is sufficient.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Then, set out a pitcher or beaker of water for students to use during the cricket dissection.
</div></li></ul></li></ol>

Animal Diversity: Form and Function of Crickets and Crayfish - Prep

Diversité animale

Form and Function of Crickets and Crayfish
ExpandThis lab involves dissection of both crickets and crayfish. You will need one cricket and one crayfish ...

Evolutionary Relationships

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Forming an Evolutionary Hypothesis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">NOTE: A cladogram is an important tool for forming an evolutionary hypothesis. A cladogram is a tree-shaped chart used to depict the hypothetical genealogical relationships between species. The tips or leaves of the chart represent specific species and the branches of the tree are different lengths. The different lengths represent the degree of change between each of the species. The common ancestor of all of the species that a specific line branches from is located at a node, where the branches intersect. Species that share a node are called a sister group.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">To begin, look at the provided blank cladogram and make a hypothesis about where the assigned animals should be placed on the tree. If a blank cladogram has not been provided please <a target="_blank" href="/files/ftp_upload/10562/Blank_Cladogram.png">download one here</a>.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Next, observe the image of the fossilized animal.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Using the morphology, or physical characteristics, of the fossil, make a hypothesis about where on your cladogram it should be placed. Add a new line or mark to indicate your proposed position for the fossil.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Comparing Gene Sequences Using BLAST
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">NOTE: Historically, cladograms have been constructed through the comparison of morphology. Now, genetic sequences can also be compared between species of interest to construct cladograms. DNA sequences are not usually preserved in fossils, so for this lab you will use the BLAST database to compare the DNA sequences of living species that are closely related to the fossil to thousands of other living species.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Before beginning this lab, your instructor will have downloaded the three preserved gene sequences to a folder on your desktop.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Navigate to the BLAST homepage, which the instructor should have left open in your browser, and click on Saved Strategies from the menu at the top of the page.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Click Open on the Evolutionary_Relationships_Gene1.txt file.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Then, click View to go to the Standard Nucleotide BLAST search page. You should be able to see the DNA sequence in the Query Sequence box at the top-right of the screen.
</div></li><li data-sub-note-item="2-6"><div class="lab-step">Scroll to the bottom of the screen and click the BLAST button. Note: It will take a few moments to process and analyze the data. 
</div></li><li data-sub-note-item="2-7"><div class="lab-step">When the data has been processed, a graphic summary will appear.  NOTE: Your query sequence is represented by the blue line at the top of the box. Each of the lines below the blue line represents another sequence in the BLAST database that matches your query. The length and location of these bars represent where and how much of the sequence match up to the query. The color of the bar represents its score, or how identical the sequence is to the query. Below the graphic summary is the Sequences producing significant alignments list, which contains descriptions of the DNA sequences retrieved from the database that most closely align with the query sentence. These are listed in descending order, from the most similar at the top to the least similar at the bottom. On the right, there are several statistics on how closely related each database sequence is to the experimental sequence. The higher the Max, Total, Query Coverage, and Identity scores are, the more similar the query and retrieved sequences are to each other. Similarly, the lower the E value number, the less likely the sequences match was found by random chance and more significantly the alignment is accurate. An E value of 0 indicates a highly significant match.
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Click on the name of the description of the most similar alignment listed. This will take you further down the page to the exact DNA sequence alignment between the retrieved sequence and the query sequence.
</div></li><li data-sub-note-item="2-9"><div class="lab-step">Click on the Sequence ID number. This will open a new tab with more specific information on the retrieved gene sequence.
</div></li><li data-sub-note-item="2-10"><div class="lab-step">Identify and record the scientific and common names of the organism, which should be listed next to Source.
</div></li><li data-sub-note-item="2-11"><div class="lab-step">Identify and record the protein that the gene codes for, which should be listed next to Definition.
</div></li><li data-sub-note-item="2-12"><div class="lab-step">Close the tab and hit Back to return to the Sequences producing significant alignments list.
</div></li><li data-sub-note-item="2-13"><div class="lab-step">Then, repeat steps 7 &#8211; 9 for the next most similar sequences.
</div></li><li data-sub-note-item="2-14"><div class="lab-step">After collecting several species names, return to the Sequences producing significant alignments list and click Select: All to check all of the boxes next to the names of each listed alignment sequence.
</div></li><li data-sub-note-item="2-15"><div class="lab-step">Click on Distance of tree results to create a phylogram based on the similarity of all of the BLAST result gene sequences to the query gene sequence.  Note: Your query fossil relative sequence will be highlighted in yellow.
</div></li><li data-sub-note-item="2-16"><div class="lab-step">Record your sequence&#8217;s location in relation to the other taxon groups shown in the tree.
</div></li><li data-sub-note-item="2-17"><div class="lab-step">Finally, return to the Saved Strategies tab and upload the next saved gene sequence.
</div></li><li data-sub-note-item="2-18"><div class="lab-step">Query the remaining two fossil relative DNA sequences as previously demonstrated (steps 1 &#8211; 16).
</div></li></ul></li><li data-note-item="3" data-parent-collapse="">Data Analysis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="3-1"><div class="lab-step">Based on your gene sequence results, come up with a second hypothesis about where your fossil specimen fit in the original cladogram.
</div></li><li data-sub-note-item="3-2"><div class="lab-step">Compare this placement with your first hypothesis.
</div></li><li data-sub-note-item="3-3"><div class="lab-step">Compare your tree with your classmates&#8217;. If any of your classmates put the fossil on a different branch, ask them how they came to that decision.
</div></li></ul></li></ol>

Evolutionary Relationships: Using BLAST to Test Evolutionary Hypotheses - Procedure

Relations évolutives

Forming an Evolutionary Hypothesis
ExpandNOTE: A cladogram is an important tool for forming an evolutionary hypothesis. A cladogram is a tree-shaped chart ...