Wir danken Mitglieder der Evans-Labor für ihre Hilfe bei der Vorbereitung dieser Präsentation. Die hier verwendeten Morpholinos wurden ursprünglich von Dr. Audrey Holtzinger validiert. TE wird durch Zuschüsse aus dem National Institutes of Health (HL064282 und HL056182) unterstützt. Tierversuche wurden in Übereinstimmung mit den Richtlinien und Vorschriften her durch das Institute for Animal Care und Verwenden eingesetzten Ausschusses, des Weill Cornell Medical College durchgeführt.

<ol>
	<li>Heicklen-Klein, A., McReynolds, L. J., Evans, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+the+zebrafish+model+to+study+GATA+transcription+factors.">Using the zebrafish model to study GATA transcription factors.</a> Semin Cell Dev Biol. 16, 95-106 (2005).</li><li>Bill, B. R., Petzold, A. M., Clark, K. J., Schimmenti, L. A., Ekker, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+primer+for+morpholino+use+in+zebrafish.">A primer for morpholino use in zebrafish.</a> Zebrafish. 6, 69-77 (2009).</li><li>Holtzinger, A., Evans, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gata5+and+Gata6+are+functionally+redundant+in+zebrafish+for+specification+of+cardiomyocytes.">Gata5 and Gata6 are functionally redundant in zebrafish for specification of cardiomyocytes.</a> Dev Biol. 312, 613-622 (2007).</li><li>Peterkin, T., Gibson, A., Patient, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redundancy+and+evolution+of+GATA+factor+requirements+in+development+of+the+myocardium.">Redundancy and evolution of GATA factor requirements in development of the myocardium.</a> Dev Biol. 311, 623-635 (2007).</li><li>Holtzinger, A., Evans, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gata4+regulates+the+formation+of+multiple+organs.">Gata4 regulates the formation of multiple organs.</a> Development. 132, 4005-4014 (2005).</li><li>Sorrentino, R. P., Gajewski, K. M., Schulz, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GATA+factors+in+Drosophila+heart+and+blood+cell+development.">GATA factors in Drosophila heart and blood cell development.</a> Semin Cell Dev Biol. 16, 107-116 (2005).</li></ol>

In dem hier beschriebenen Experiment, kombiniert man zwei Morpholinos, von denen jeder allein erzeugen eine deutliche Reihe von Phänotypen, und fand eine ganz andere Phänotyp, wenn sie co-injiziert zusammen. Natürlich benötigten wir eine Rechtfertigung dafür dieses Experiment in den ersten Platz. Wir vermuteten, dass die beiden Gene könnten sich gegenseitig für eine frühere Funktion zu kompensieren, in diesem Fall kardiale Spezifikation. Dies liegt daran, die Gene sehr verwandt sind (und in der Lage die Bindung an den gleichen DNA-Sequenzen) und sind in überlappenden Mustern während der Embryogenese 5 ausgedrückt. Darüber hinaus gaben genetische Experimente in Drosophila, dass GATA-Transkriptionsfaktoren sollten für die Herz-Spezifikation 6 erforderlich sein. Allerdings gibt es andere Situationen, die diese Strategie für das Testen funktionelle Redundanz oder allgemein für genetische Interaktionen genutzt werden könnten. Erstens könnte Knockdown von einem oder beiden Genen erzeugt keine offensichtlichen Phänotyp. In diesem Fall gibt es keine definierten Schwellenwert für jedes Gen, und die Menge der Morpholino zu nutzen wird empirisch festgelegt werden, begrenzt durch, wie gut sie von den Embryonen vertragen. Auch hier wird die Begründung für die Prüfung Entschädigung wahrscheinlich, dass die Gene sehr verwandt sind und von der Bestätigung Co-Expressionsmuster. Zweitens genetischen Wechselwirkungen können für ein beliebiges Gen-Paar mit Sub-Threshold-Mengen Morpholinos getestet werden. In dieser Strategie ist die maximale Menge, die nicht erzeugt einen Phänotyp für jeden Morpholino verwendet. Wenn die Kombination beider Morpholinos erzeugt einen Phänotyp, bietet diese stichhaltigen Beweise für eine genetische Interaktion, obwohl es vielleicht ganz indirekte oder sogar stellen parallele Wege. Drittens Co-Injektion von einem zweiten Morpholino können Rettungs den Phänotyp der ersten, wenn die beiden Gene in einer antagonistischen Weise (was wiederum kann indirekt) zu interagieren. Zwar gibt es keine definierte Grenze, wie viele verschiedene Gene gezielt werden kann, in einem praktischen Sinne ist es wohl 3-4 Genen, abhängig von der Höhe des jeweiligen Morpholino, dass bei einer Schwelle Reaktion benötigt wird. Während dieser allgemeinen Ansatz der Verwendung der reversen Genetik, neue Genfunktionen offenbaren relativ hohem Durchsatz, gibt es eine Reihe von Vorbehalten zu erwägen über Morpholinos. Bevor die Kombination Morpholinos, sind beträchtliche Anstrengungen erforderlich, um einzelne Reagenzien zu validieren, sofern dies nicht bereits getan. Jede einzelne Morpholino kann nicht funktionieren, während andere erzeugen kann off-targeting &quot;Artefakt&quot; Phänotypen besonders mit der Aktivierung der weit verbreiteten Apoptose assoziiert. Die Reagenzien sind nicht billig, und wenn zwei oder mehr Morpholinos erforderlich sind, um jedes Gen zu validieren, diese Investition können erheblich sein. Mehrere Überlegungen leiten die experimentelle Strategie. i) Gibt es eine bekannte Mutantenphänotyps? Wenn ja, sollte ein einzelner Phäno-Kopieren Morpholino ausreichend sein. ii) Gibt es einen Antikörper zur Verfügung? Wenn ja, können eine Übersetzung-Blocker bevorzugt werden, und wenn nicht, wird es wichtig sein zu dokumentieren, dass ein Spleiß-Blocker effektiv Ziele der prä-mRNA. iii) Können Sie retten die morphant durch Injektion von mRNA? Wenn dies funktioniert, bietet es hervorragende Beweise für Morpholino Spezifität. Allerdings kann es oft nicht, durch falsche Ausrichtung der injizierten mRNA. Rettung könnte auch getestet Transposon-basierten Transgenese werden, da dies engere räumliche und zeitliche Kontrolle über Ausdruck der gezielten Gen ermöglichen kann. In jedem Fall ist es wichtig, sicherzustellen, dass die Rettung Gen nicht durch den Morpholino ausgerichtet.

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<td>Invitrogen</td>
<td>15510-027</td>
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<td>14-357Q</td>
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<td>08-572-6D</td>
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<td>2026333</td>
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<td>801VWR</td>
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<td>M5904</td>
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<td>Kimwipes</td>
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<td>Kimberly-Clark</td>
<td>34155</td>
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<tr>
<td>gata5 splice site morpholino</td>
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<td>Genetools, LLC</td>
<td>&nbsp;</td>
<td>5'-TCTTAAGATTTTTACCTATACTGGA-3'</td>
</tr>
<tr>
<td>gata5 ATG Blocker</td>
<td>&nbsp;</td>
<td>Genetools, LLC</td>
<td>&nbsp;</td>
<td>5'-AAGATAAAGCCAGGCTCGAATACAT-3'</td>
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<tr>
<td>gata6 Long Isoform ATG Blocker</td>
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<td>Genetools, LLC</td>
<td>&nbsp;</td>
<td>5'-AGCTGTTATCACCCAGGTCCATCCA-3'</td>
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<td>Disposable Pasteur Pipette</td>
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<td>Fisher Scientific</td>
<td>13-678-20B</td>
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<td>Tricaine Methanesulfonate</td>
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<td>Argent Chemical Laboratories</td>
<td>MS-222</td>
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<td>ICN Biomedicals</td>
<td>155495</td>
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<td>Fisher</td>
<td>11-718-4</td>
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<td>Sharp forceps</td>
<td>&nbsp;</td>
<td>Dumont</td>
<td>&nbsp;</td>
<td>Size 55</td>
</tr>
<tr>
<td>Depression Microslides</td>
<td>&nbsp;</td>
<td>VWR</td>
<td>48339-009</td>
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a reverse genetic approach to test functional redundancy during embryogenesis

Gene-Funktion während der Embryogenese wird typischerweise durch loss-of-function Experimente definiert, zum Beispiel durch gezielte Mutagenese (KO) in der Maus. In der Zebrafisch-Modell, über wirksame reverse genetische Techniken entwickelt, mit Mikroinjektion von Gen-spezifischen Antisense Morpholinos. Morpholinos Ziel einer mRNA durch spezifische Basenpaarung und Block Genfunktion vorübergehend durch die Hemmung der Translation oder Spleißen für mehrere Tage während der Embryogenese (Zuschlag). Doch bei Wirbeltieren wie Maus oder Zebrafisch, können einige Funktionen von Genen durch diese Ansätze durch die Anwesenheit eines anderen Gens, das für den Verlust entschädigt verdeckt werden. Dies gilt insbesondere für die Gen-Familien, die Schwester Gene, die in der gleichen entwickelnde Gewebe co-exprimiert. In Zebrafisch können funktionelle Kompensation in einem relativ hohen Durchsatz Weise getestet werden, durch Co-Injektion von Morpholinos dieses Ziel Knockdown von beiden Genen gleichzeitig. Ebenso mit Morpholinos, kann eine genetische Interaktion zwischen zwei Genen, die durch Knockdown beider Gene demonstriert zusammen mit sub-Schwellenwerte. Zum Beispiel kann Morpholinos titriert, so dass weder einzelne Knockdown einen Phänotyp erzeugt werden. Wenn unter diesen Bedingungen, Ursachen Co-Injektion von sowohl Morpholinos einem Phänotyp, ist eine genetische Interaktion gezeigt. Hier zeigen wir, wie man funktionale Redundanz im Rahmen von zwei verwandten GATA-Transkriptionsfaktoren zeigen. GATA Faktoren sind für die Spezifikation von kardialen Vorläuferzellen notwendig, aber dies ist nur durch den Verlust der beiden Gata5 und Gata6 enthüllt. Wir zeigen, wie die Durchführung Mikroinjektion Experimente bestätigen die Morpholinos, und bewerten die ausgeglichen Phänotyp für Kardiogenese.

Watch this Scientific Journal Video about A Reverse Genetic Approach to Test Functional Redundancy During Embryogenesis at JoVE.com

A Reverse Genetic Approach to Test Functional Redundancy During Embryogenesis

Gene-Funktion kann in loss-of-function Experimente verdeckt werden, wenn es eine Kompensation durch ein anderes Gen. Der Zebrafisch-Modell bietet eine relativ hohem Durchsatz, um eine solche funktionelle Redundanz in lebenden Embryonen zu offenbaren.

Ein Reverse Genetic Ansatz zur funktionellen Redundanz während der Embryogenese-Test

Gene function during embryogenesis is typically defined by loss-of-function experiments, for example by targeted mutagenesis (knockout) in the mouse. In ...

a-reverse-genetic-approach-to-test-functional-redundancy-during

Nanyang Technological University

Research

JoVE Journal

Biology

11.9K Aufrufe.  Weill Cornell Medical College of Cornell University. Gene-Funktion kann in loss-of-function Experimente verdeckt werden, wenn es eine Kompensation durch ein anderes Gen. Der Zebrafisch-Modell bietet eine relativ hohem Durchsatz, um eine solche funktionelle Redundanz in lebenden Embryonen zu offenbaren.

Serie: A Reverse Genetic Approach to Test Functional Redundancy During Embryogenesis

Light/dark Transition Test for Mice

Although all of the mouse genome sequences have been determined, we do not yet know the functions of most of these genes. Gene-targeting techniques, however, can be used to delete or manipulate a specific gene in mice. The influence of a given gene on a specific behavior can then be determined by conducting behavioral analyses of the mutant mice. As a test for behavioral phenotyping of mutant mice, the light/dark transition test is one of the most widely used tests to measure anxiety-like behavior in mice. The test is based on the natural aversion of mice to brightly illuminated areas and on their spontaneous exploratory behavior in novel environments. The test is sensitive to anxiolytic drug treatment. The apparatus consists of a dark chamber and a brightly illuminated chamber. Mice are allowed to move freely between the two chambers. The number of entries into the bright chamber and the duration of time spent there are indices of bright-space anxiety in mice. To obtain phenotyping results of a strain of mutant mice that can be readily reproduced and compared with those of other mutants, the behavioral test methods should be as identical as possible between laboratories. The procedural differences that exist between laboratories, however, make it difficult to replicate or compare the results among laboratories. Here, we present our protocol for the light/dark transition test as a movie so that the details of the protocol can be demonstrated. In our laboratory, we have assessed more than 60 strains of mutant mice using the protocol shown in the movie. Those data will be disclosed as a part of a public database that we are now constructing.

Visualization of the protocol will facilitate understanding of the details of the entire experimental procedure, allowing for standardization of the protocols used across laboratories and comparisons of the behavioral phenotypes of various strains of mutant mice assessed using this test.

The light/dark transition test is one of the most widely used tests to measure anxiety-like behavior in mice. Here, we present a movie that shows detailed procedures on how we conduct the test.

Hell / Dunkel Transition Test für Mäuse

Although all of the mouse genome sequences have been determined, we do not yet know the functions of most of these genes. Gene-targeting techniques, ...

Forschung

Biologie

Method for Culture of Early Chick Embryos ex vivo (New Culture)

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying  the formation and patterning of brain, neural tube, somite and heart primordia. Applications of chick embryo culture include electroporation of DNA or RNA constructs in order to analyze gene function, grafts of growth factor coated beads such as FGFs and BMPs , as well as whole mount in situ hybridization and immunohistochemistry. This video demonstrates the different steps in chick embryo culture; First, the embryo is explanted in saline. Then, the embryo is centered on a glass ring. The membranes surrounding the embryo are lifted along the walls of the ring. The ring is then placed in a culture dish containing a pool of albumine. The culture dish is sealed and placed in a humid chamber, where the embryo is cultured for up to 24 hrs. Finally, the embryo is removed from the ring, fixed and processed for further applications. A troubleshooting guide is also presented.

Method for Culture of Early Chick Embryos ex vivo New Culture

This video demonstrates New culture, a method by which chick embryos are cultured outside the egg for up to 24 hr. This method enables one to study early development (primitive streak to 14 som.), a period corresponding to E7-9 in mouse. Applications of this technique include electroporation, in situ hybridization and immunohistochemistry.

Method for Culture of Early Hühnerembryonen ex vivo (New Culture)

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ...

Double Whole Mount in situ Hybridization of Early Chick Embryos

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying  gene expression in brain, neural tube, somite and heart primordia formation. This video demonstrates the different steps in 2-color whole mount in situ hybridization; First, the embryo is dissected from the egg and fixed in paraformaldehyde. Second, the embryo is processed for prehybridization. The embryo is then hybridized with two different probes, one coupled to DIG, and one coupled to FITC.  Following overnight hybridization, the embryo is incubated with DIG coupled antibody. Color reaction for DIG substrate is performed, and the region of interest appears blue. The embryo is then incubated with FITC coupled antibody. The embryo is processed for color reaction with FITC, and the region of interest appears red. Finally, the embryo is fixed and processed for phtograph and sectioning. A troubleshooting guide is also presented.

This video demonstrates 2-color whole mount in situ hybridization, a method by which the spatial and temporal expression pattern of 2 different genes can be visualized in young chick embryos. This method was originally introduced by David Wilkinson, Domingos Henrique, Phil Ingham and David Ish -Horowicz.

Doppel Whole Mount in situ Hybridisierung von Anfang Hühnerembryonen

Method for Whole Mount Antibody Staining in Chick

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying antibody expression in developing brain, neural tube and somite. This video demonstrates the different steps in whole-mount antibody staining using HRP conjugated secondary antibodies; First, the embryo is dissected from the egg and fixed in paraformaldehyde. Second, endogenous peroxidase is inactivated; The embryo is then exposed to primary antibody. After several washes, the embryo is incubated with secondary antibody conjugated to HRP. Peroxidase activity is revealed using reaction with diaminobenzidine substrate. Finally, the embryo is fixed and processed for photography and sectioning. The advantage of this method over the use of fluorescent antibodies is that embryos can be processed for wax sectioning, thus enabling the study of antigen sites in cross section. This method was originally introduced by Jane Dodd and Tom Jessell 1.

This video demonstrates whole mount immunohistochemistry, a method by which the spatial and temporal expression pattern of an antigen can be visualized in young chick embryos. This method was originally introduced by Jane Dodd and Tom Jessell.

Verfahren zur Whole Mount Antikörper-Färbung in Küken

Assay for Neural Induction in the Chick Embryo

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying the formation and initial patterning of the nervous system. This video demonstrates how to graft organizer tissue into a host, a method by which Hensen s node (the organizer in the chick embryo) is grafted to a host competent ectoderm. The organizer graft instructs overlying na ve tissue to adopt a neural fate via neural inducing signals. This mechanism is referred to as neural induction, and constitutes the initial step in the formation of brain and spinal cord in amniotes. This method is essentially used for the characterization of putative neural inducing molecules in chick. This video demonstrates the different steps in the assay for neural induction; First, the donnor embryo is explanted and pinned on a dish. Then, the host embryo is prepared for New culture. The graft is excised and transplanted to the host area pellucida margin. The host is cultured for 18-22 hrs. The assembly is fixed and processed for further applications (e.g. in situ hybridization). This method was originally devised by Waddington 1,2 and Gallera 3,4.

Neural induction is the first step in the formation of the brain. It is a mechanism by which Hensen's node (organizer), instructs adjacent tissue to adopt a neural fate, i.e. to give rise to the nervous system. This video demonstrates an assay for neural induction in chick embryo.

Assay für Neural Induction im Hühnerembryo

Elevated Plus Maze for Mice

Although the mouse genome is now completely sequenced, the functions of most of the genes expressed in the brain are not known. The influence of a given gene on a specific behavior can be determined by behavioral analysis of mutant mice. If a target gene is expressed in the brain, behavioral phenotype of the mutant mice could elucidate the genetic mechanism of normal behaviors. The elevated plus maze test is one of the most widely used tests for measuring anxiety-like behavior. The test is based on the natural aversion of mice for open and elevated areas, as well as on their natural spontaneous exploratory behavior in novel environments. The apparatus consists of open arms and closed arms, crossed in the middle perpendicularly to each other, and a center area. Mice are given access to all of the arms and are allowed to move freely between them. The number of entries into the open arms and the time spent in the open arms are used as indices of open space-induced anxiety in mice. Unfortunately, the procedural differences that exist between laboratories make it difficult to duplicate and compare results among laboratories. Here, we present a detailed movie demonstrating our protocol for the elevated plus maze test. In our laboratory, we have assessed more than 90 strains of mutant mice using the protocol shown in the movie. These data will be disclosed as a part of a public database that we are now constructing.
Visualization of the protocol will promote better understanding of the details of the entire experimental procedure, allowing for standardization of the protocols used in different laboratories and comparisons of the behavioral phenotypes of various strains of mutant mice assessed using this test. 


The elevated plus maze test is one of the most widely used tests for measuring anxiety-like behavior in mice. Here, we present a movie showing the detailed procedures for conducting the test.

Elevated Plus Maze für Mäuse

Although the mouse genome is now completely sequenced, the functions of most of the genes expressed in the brain are not known. The influence of a given ...

Dissection of Hippocampal Dentate Gyrus from Adult Mouse

The hippocampus is one of the most widely studied areas in the brain because of its important functional role in memory processing and learning, its remarkable neuronal cell plasticity, and its involvement in epilepsy, neurodegenerative diseases, and psychiatric disorders. The hippocampus is composed of distinct regions; the dentate gyrus, which comprises mainly granule neurons, and Ammon's horn, which comprises mainly pyramidal neurons, and the two regions are connected by both anatomic and functional circuits. Many different mRNAs and proteins are selectively expressed in the dentate gyrus, and the dentate gyrus is a site of adult neurogenesis; that is, new neurons are continually generated in the adult dentate gyrus. To investigate mRNA and protein expression specific to the dentate gyrus, laser capture microdissection is often used. This method has some limitations, however, such as the need for special apparatuses and complicated handling procedures. In this video-recorded protocol, we demonstrate a dissection technique for removing the dentate gyrus from adult mouse under a stereomicroscope. Dentate gyrus samples prepared using this technique are suitable for any assay, including transcriptomic, proteomic, and cell biology analyses. We confirmed that the dissected tissue is dentate gyrus by conducting real-time PCR of dentate gyrus-specific genes, tryptophan 2,3-dioxygenase (TDO2) and desmoplakin (Dsp), and Ammon's horn enriched genes, Meis-related gene 1b (Mrg1b) and TYRO3 protein tyrosine kinase 3 (Tyro3). The mRNA expressions of TDO2 and Dsp in the dentate gyrus samples were detected at obviously higher levels, whereas Mrg1b and Tyro3 were lower levels, than those in the Ammon's horn samples. To demonstrate the advantage of this method, we performed DNA microarray analysis using samples of whole hippocampus and dentate gyrus. The mRNA expression of TDO2 and Dsp, which are expressed selectively in the dentate gyrus, in the whole hippocampus of alpha-CaMKII+/- mice, exhibited 0.037 and 0.10-fold changes compared to that of wild-type mice, respectively. In the isolated dentate gyrus, however, these expressions exhibited 0.011 and 0.021-fold changes compared to that of wild-type mice, demonstrating that gene expression changes in dentate gyrus can be detected with greater sensitivity. Taken together, this convenient and accurate dissection technique can be reliably used for studies focused on the dentate gyrus.

A dissection technique for removal of the dentate gyrus from adult mouse under a stereomicroscope was demonstrated in this video-recorded protocol.

Dissection der hippocampalen von erwachsenen Maus

The hippocampus is one of the most widely studied areas in the brain because of its important functional role in memory processing and learning, its ...

A Practical Approach to Genetic Inducible Fate Mapping: A Visual Guide to Mark and Track Cells In Vivo

Fate maps are generated by marking and tracking cells in vivo to determine how progenitors contribute to specific structures and cell types in developing and adult tissue. An advance in this concept is Genetic Inducible Fate Mapping (GIFM), linking gene expression, cell fate, and cell behaviors in vivo, to create fate maps based on genetic lineage.
GIFM exploits X-CreER lines where X is a gene or set of gene regulatory elements that confers spatial expression of a modified bacteriophage protein, Cre recombinase (CreERT). CreERT contains a modified estrogen receptor ligand binding domain which renders CreERT sequestered in the cytoplasm in the absence of the drug tamoxifen. The binding of tamoxifen releases CreERT, which translocates to the nucleus and mediates recombination between DNA sequences flanked by loxP sites. In GIFM, recombination typically occurs between a loxP flanked Stop cassette preceding a reporter gene such as GFP.
Mice are bred to contain either a region- or cell type-specific CreER and a conditional reporter allele. Untreated mice will not have marking because the Stop cassette in the reporter prevents further transcription of the reporter gene. We administer tamoxifen by oral gavage to timed-pregnant females, which provides temporal control of CreERT release and subsequent translocation to the nucleus removing the Stop cassette from the reporter. Following recombination, the reporter allele is constitutively and heritably expressed. This series of events marks cells such that their genetic history is indelibly recorded. The recombined reporter thus serves as a high fidelity genetic lineage tracer that, once on, is uncoupled from the gene expression initially used to drive CreERT.
We apply GIFM in mouse to study normal development and ascertain the contribution of genetic lineages to adult cell types and tissues. We also use GIFM to follow cells on mutant genetic backgrounds to better understand complex phenotypes that mimic salient features of human genetic disorders.
This video article guides researchers through experimental methods to successfully apply GIFM. We demonstrate the method using our well characterized Wnt1-CreERT;mGFP mice by administering tamoxifen at embryonic day (E)8.5 via oral gavage followed by dissection at E12.5 and analysis by epifluorescence stereomicroscopy. We also demonstrate how to micro-dissect fate mapped domains for explant preparation or FACS analysis and dissect adult fate-mapped brains for whole mount fluorescent imaging. Collectively, these procedures allow researchers to address critical questions in developmental biology and disease models.

A Practical Approach to Genetic Inducible Fate Mapping: A Visual Guide to Mark and Track Cells In Vivo

Genetic Inducible Fate Mapping (GIFM) marks and tracks cells with fine spatial and temporal control in vivo and elucidates how cells from a specific genetic lineage contribute to developing and adult tissues. Demonstrated here are the techniques required to fate map E12.5 mouse embryos for epifluorescent and explant analysis.

A Practical Approach to Genetic Inducible Fate Mapping: A Visual Guide to Mark und Track Cells In Vivo</em

Fate maps are generated by marking and tracking cells in vivo to determine how progenitors contribute to specific structures and cell types in developing ...

An Allele-specific Gene Expression Assay to Test the Functional Basis of Genetic Associations

The number of significant genetic associations with common complex traits is constantly increasing. However, most of these associations have not been understood at molecular level. One of the mechanisms mediating the effect of DNA variants on phenotypes is gene expression, which has been shown to be particularly relevant for complex traits1.
This method tests in a cellular context the effect of specific DNA sequences on gene expression. The principle is to measure the relative abundance of transcripts arising from the two alleles of a gene, analysing cells which carry one copy of the DNA sequences associated with disease (the risk variants)2,3. Therefore, the cells used for this method should meet two fundamental genotypic requirements: they have to be heterozygous both for DNA risk variants and for DNA markers, typically coding polymorphisms, which can distinguish transcripts based on their chromosomal origin (Figure 1). DNA risk variants and DNA markers do not need to have the same allele frequency but the phase (haplotypic) relationship of the genetic markers needs to be understood. It is also important to choose cell types which express the gene of interest. This protocol refers specifically to the procedure adopted to extract nucleic acids from fibroblasts but the method is equally applicable to other cells types including primary cells.
DNA and RNA are extracted from the selected cell lines and cDNA is generated. DNA and cDNA are analysed with a primer extension assay, designed to target the coding DNA markers4. The primer extension assay is carried out using the MassARRAY (Sequenom)5 platform according to the manufacturer's specifications. Primer extension products are then analysed by matrix-assisted laser desorption/ionization time of-flight mass spectrometry (MALDI-TOF/MS). Because the selected markers are heterozygous they will generate two peaks on the MS profiles. The area of each peak is proportional to the transcript abundance and can be measured with a function of the MassARRAY Typer software to generate an allelic ratio (allele 1: allele 2) calculation. The allelic ratio obtained for cDNA is normalized using that measured from genomic DNA, where the allelic ratio is expected to be 1:1 to correct for technical artifacts. Markers with a normalised allelic ratio significantly different to 1 indicate that the amount of transcript generated from the two chromosomes in the same cell is different, suggesting that the DNA variants associated with the phenotype have an effect on gene expression. Experimental controls should be used to confirm the results.

Genetic associations often remain unexplained at a functional level. This method aims to assess the effect of phenotype-associated genetic markers on gene expression by analyzing cells heterozygous for transcribed SNPs. The technology allows accurate measurement by MALDI-TOF mass spectrometry to quantify allele-specific primer extension products.

Ein Allel-spezifische Gene Expression Assay zur Funktionsanalyse Grundlage genetischer Verbände testen

The number of significant genetic associations with common complex traits is constantly increasing. However, most of these associations have not been ...

Pharmacological and Functional Genetic Assays to Manipulate Regeneration of the Planarian Dugesia japonica

Free-living planarian flatworms have a long history of experimental usage owing to their remarkable regenerative abilities1. Small fragments excised from these animals reform the original body plan following regeneration of missing body structures. For example if a 'trunk' fragment is cut from an intact worm, a new 'head' will regenerate anteriorly and a 'tail' will regenerate posteriorly restoring the original 'head-to-tail' polarity of body structures prior to amputation (Figure 1A).
Regeneration is driven by planarian stem cells, known as 'neoblasts' which differentiate into ~30 different cell types during normal body homeostasis and enforced tissue regeneration. This regenerative process is robust and easy to demonstrate. Owing to the dedication of several pioneering labs, many tools and functional genetic methods have now been optimized for this model system. Consequently, considerable recent progress has been made in understanding and manipulating the molecular events underpinning planarian developmental plasticity2-9.
The planarian model system will be of interest to a broad range of scientists. For neuroscientists, the model affords the opportunity to study the regeneration of an entire nervous system, rather than simply the regrowth/repair of single nerve cell process that typically are the focus of study in many established models. Planarians express a plethora of neurotransmitters10, represent an important system for studying evolution of the central nervous system11, 12 and have behavioral screening potential13, 14. 
Regenerative outcomes are amenable to manipulation by pharmacological and genetic apparoaches. For example, drugs can be screened for effects on regeneration simply by placing body fragments in drug-containing solutions at different time points after amputation. The role of individual genes can be studied using knockdown methods (in vivo RNAi), which can be achieved either through cycles of microinjection or by feeding bacterially-expressed dsRNA constructs8, 9, 15. Both approaches can produce visually striking phenotypes at high penetrance- for example, regeneration of bipolar animals16-21. To facilitate adoption of this model and implementation of such methods, we showcase in this video article protocols for pharmacological and genetic assays (in vivo RNAi by feeding) using the planarian Dugesia japonica.

Pharmacological and Functional Genetic Assays to Manipulate Regeneration of the Planarian Dugesia japonica

An attractive model for studying stem cell differentiation within a live animal is the planarian flatworm. Regeneration is studied by simple amputation experiments that are easily performed in a basic laboratory and are amenable to pharmacological and genetic (in vivo RNAi) manipulation as detailed by protocols in this article.

Pharmakologische und Functional genetischen Tests zu manipulieren Regeneration der Planarien Dugesia japonica</em

Free-living planarian flatworms have a long history of experimental usage owing to their remarkable regenerative abilities1. Small fragments excised from ...

Ein Reverse Genetic Ansatz zur funktionellen Redundanz während der Embryogenese-Test

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