This work was funded by National Natural Science Foundation of China (31671257) and Hubei Collaborative Innovation Center for Grain Industry (LXT-16-18).

1. Arabidopsis vertical growth in MS medium
<ol>
	<li>The interior of laminar flow cabinet needs to be treated with 30 min UV light and 15 min airflow before usage. Make sure to close the glass door when UV light is on. Spray all tools and plates with 70% ethanol before placing them in the cabinet.</li>
	<li>Prepare the Murashige and Skoog (MS) medium in a standard 90 mm-diameter Petri dish under a laminar flow cabinet. 
	NOTE: The MS medium contains the following components: 20.6 mM NH4NO3, 18.8 mM KNO3, 1.25 mM KH2PO4, 1.5 mM MgSO4&#183;7H2O, 3 mM CaCl2&#183;2H2O, 0.1 mM MnSO4&#183;H2O, 1.03 &#181;M Na2MoO4&#183;2H2O, 0.1 mM H3BO3, 30 &#181;M ZnSO4&#183;7H2O, 0.1 &#181;M CuSO4&#183;5H2O, 0.1 &#181;M CoCl2&#183;6H2O, 1.39 &#181;M KI, 97 &#181;M FeSO4&#183;7H2O, 114.5 &#181;M ethylenediaminetetraacetic acid (EDTA), 4.07 &#181;M nicotinic Acid, 2.44 &#181;M pyridoxine HCl, 0.15 &#181;M thiamine HCl, 2.68 mM glycine, 555 &#181;M myo-inositol, 87.7 mM sucrose and 10 g/L agar.</li>
	<li>Moisturize the sterilized tips or toothpicks by touching the tip or toothpicks to the MS medium, then dip the sterilized seeds one by one onto the fixed position of each Petri dish indicated by the seeding card.</li>
	<li>Seal the Petri dish with paraffin film and sticky tape and place it vertically on a clear stand in a growth room (22 &#176;C, 70% moisture) with a day cycle of 16 h of light and 8 h of darkness (lighting from 6 am to 10 pm). The Arabidopsis plant is ready for CFDA loading on day 9-13 after sowing. 
	NOTE: The following procedure is performed in the afternoon from 2 pm to 5 pm.</li>
</ol>
2. CFDA loading with the root cutting procedure
<ol>
	<li>Prepare fresh CFDA working solution immediately before use. Dilute the 1 mM CFDA stock solution stored in -20 &#176;C freezer with sterile ultrapure water to a working concentration of 5 &#181;M.</li>
	<li>Cut the micro-porous paraffin membrane film (see Table of Materials) into small pieces of 3 mm x 3 mm size.</li>
	<li>Uncover the growing plants in the room at 22 &#176;C and clear the excess moisture with a paper towel. Place the small film pieces below each root. 
	NOTE: From this to step 2.6, the whole process should be completed within 15 min.</li>
	<li>Lift the plants onto the Petri dish lid. Cut the roots in a position about 5-10 mm below the root-hypocotyl junction. Place the shoot part back on to the film on the medium.</li>
	<li>Carefully apply 0.25 &#181;L of CFDA onto the cutting end of each root under a dissecting microscope. Avoid splashing to other parts of plant.</li>
	<li>Cover the plate and leave the plants under light for 2-3 h (22 &#176;C) in the growth room.</li>
	<li>Rinse the stained plants three times sequentially in three separate beakers filled with distilled water, then observe the plants under a stereo-fluorescence microscope with zoom from 1.4x to 3.3x (see the Table of Materials). For fluorescence detection, use a high efficiency filter cube (470/20 nm excitation, 495 nm split and 525/50 nm emission) mounted to transmit the fluorescence signal.</li>
</ol>
3. CFDA loading with hypocotyl-pinching procedure
<ol>
	<li>Prepare fresh CFDA working solution immediately before use. Dilute the 1 mM CFDA stock solution stored in -20 &#176;C freezer with sterile ultrapure water (see the Table of Materials) to a working concentration of 5 &#181;M.</li>
	<li>Cut the micro-porous paraffin membrane film (see Table of Materials) into small pieces of 3 mm x 3 mm size.</li>
	<li>Uncover the growing plants in the room at 22 &#176;C and clear the excess moisture with a paper towel. 
	NOTE: From this to step 3.7, the whole process should be completed within 15 min.</li>
	<li>Lay a small piece of film under the root-hypocotyl junction of each plant.</li>
	<li>Use forceps to gently pinch the hypocotyl near to the root-hypocotyl junction under a dissecting microscope.</li>
	<li>Carefully apply 0.1 &#181;L of CFDA onto the wound site under a dissecting microscope. Avoid splashing to other parts of plant.</li>
	<li>Cover the plate, and leave the plants under light (22 &#176;C) for 2-3 h.</li>
	<li>Rinse the stained plants three times sequentially in three separate beakers filled with distilled water, then observe the plants under a stereo-fluorescence microscope with zoom from 1.4x to 3.3x (see the Table of Materials). For fluorescence detection, mount a high efficiency filter cube (470/20 nm excitation, 495 nm split and 525/50 nm emission) to transmit the fluorescence signal.</li>
</ol>

<ol>
	<li>Grignon, N., Touraine, B., Durand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=6(5)Carboxyfluorescein+as+a+tracer+of+phloem+sap+translocation.">6(5)Carboxyfluorescein as a tracer of phloem sap translocation.</a> American Journal of Botany. 76, 871-877 (1989).</li><li>Wright, K. M., Oparka, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+fluorescent+probe+HPTS+as+a+phloem-mobile,+symplastic+tracer:+an+evaluation+using+confocal+laser+scanning+microscopy.">The fluorescent probe HPTS as a phloem-mobile, symplastic tracer: an evaluation using confocal laser scanning microscopy.</a> Journal of Experimental Botany. 47 (3), 439-445 (1996).</li><li>Oparka, K. J., Prior, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Movement+of+Lucifer+Yellow+CH+in+potato+tuber+storage+tissues:+A+comparison+of+symplastic+and+apoplastic+transport.">Movement of Lucifer Yellow CH in potato tuber storage tissues: A comparison of symplastic and apoplastic transport.</a> Planta. 176 (4), 533-540 (1988).</li><li>Knoblauch, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multispectral+Phloem-Mobile+Probes:+Properties+and+Applications.">Multispectral Phloem-Mobile Probes: Properties and Applications.</a> Plant Physiology. 167 (4), 1211-1220 (2015).</li><li>Oparka, K. J., Duckett, C. M., Prior, D. A. M., Fisher, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+imaging+of+phloem+unloading+in+the+root+tip+of+Arabidopsis.">Real-time imaging of phloem unloading in the root tip of Arabidopsis.</a> The Plant Journal. 6 (5), 759-766 (1994).</li><li>Viola, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuberization+in+Potato+Involves+a+Switch+from+Apoplastic+to+Symplastic+Phloem+Unloading.">Tuberization in Potato Involves a Switch from Apoplastic to Symplastic Phloem Unloading.</a> The Plant Cell. 13 (2), 385-398 (2001).</li><li>Roberts, A. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phloem+Unloading+in+Sink+Leaves+of+Nicotiana+benthamiana:+Comparison+of+a+Fluorescent+Solute+with+a+Fluorescent+Virus.">Phloem Unloading in Sink Leaves of Nicotiana benthamiana: Comparison of a Fluorescent Solute with a Fluorescent Virus.</a> The Plant Cell. 9 (8), 1381-1396 (1997).</li><li>P&#233;ron, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Insights+into+Phloem+Unloading+and+Expression+of+Sucrose+Transporters+in+Vegetative+Sinks+of+the+Parasitic+Plant+Phelipanche+ramosa+L+(Pomel).">New Insights into Phloem Unloading and Expression of Sucrose Transporters in Vegetative Sinks of the Parasitic Plant Phelipanche ramosa L (Pomel).</a> Frontiers in Plant Science. 7 (2048), (2017).</li><li>Spallek, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interspecies+hormonal+control+of+host+root+morphology+by+parasitic+plants.">Interspecies hormonal control of host root morphology by parasitic plants.</a> Proceedings of the National Academy of Sciences of the USA. 114 (20), 5283-5288 (2017).</li><li>Complainville, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nodule+initiation+involves+the+creation+of+a+new+symplasmic+field+in+specific+root+cells+of+medicago+species.">Nodule initiation involves the creation of a new symplasmic field in specific root cells of medicago species.</a> The Plant Cell. 15 (12), 2778-2791 (2003).</li><li>Bederska, M., Borucki, W., Znojek, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Movement+of+fluorescent+dyes+Lucifer+Yellow+(LYCH)+and+carboxyfluorescein+(CF)+in+Medicago+truncatula+Gaertn.+roots+and+root+nodules.">Movement of fluorescent dyes Lucifer Yellow (LYCH) and carboxyfluorescein (CF) in Medicago truncatula Gaertn. roots and root nodules.</a> Symbiosis. 58 (1-3), 183-190 (2012).</li><li>Robards, A. W., Lucas, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmodesmata.">Plasmodesmata.</a> Annual Review of Plant Physiology and Plant Molecular Biology. 41 (1), 369-419 (1990).</li><li>Roberts, A. G., Oparka, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmodesmata+and+the+control+of+symplastic+transport.">Plasmodesmata and the control of symplastic transport.</a> Plant, Cell &amp; Environment. 26 (1), 103-124 (2003).</li><li>Duckett, C. M., Oparka, K. J., Prior, D. A. M., Dolan, L., Roberts, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dye-coupling+in+the+root+epidermis+of+Arabidopsis+is+progressively+reduced+during+development.">Dye-coupling in the root epidermis of Arabidopsis is progressively reduced during development.</a> Development. 120 (11), 3247-3255 (1994).</li><li>Palevitz, B. A., Hepler, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+dye+coupling+of+stomatal+cells+of+Allium+and+Commelina+demonstrated+by+microinjection+of+Lucifer+yellow.">Changes in dye coupling of stomatal cells of Allium and Commelina demonstrated by microinjection of Lucifer yellow.</a> Planta. 164 (4), 473-479 (1985).</li><li>van Bel, A. J. E., Kempers, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Symplastic+isolation+of+the+sieve+element-companion+cell+complex+in+the+phloem+of+Ricinus+communis+and+Salix+alba+stems.">Symplastic isolation of the sieve element-companion cell complex in the phloem of Ricinus communis and Salix alba stems.</a> Planta. 183 (1), 69-76 (1991).</li><li>Erwee, M. G., Goodwin, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Symplast+domains+in+extrastelar+tissues+of+Egeria+densa+Planch.">Symplast domains in extrastelar tissues of Egeria densa Planch.</a> Planta. 163 (1), 9-19 (1985).</li><li>Oparka, K. J., Prior, D. A. M., Wright, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Symplastic+communication+between+primary+and+developing+lateral+roots+of+Arabidopsis+thaliana.">Symplastic communication between primary and developing lateral roots of Arabidopsis thaliana.</a> Journal of Experimental Botany. 46 (2), 187-197 (1995).</li><li>Christensen, N. M., Faulkner, C., Oparka, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+Unidirectional+Flow+through+Plasmodesmata.">Evidence for Unidirectional Flow through Plasmodesmata.</a> Plant Physiology. 150 (1), 96-104 (2009).</li><li>Wr&#243;bel-Marek, J., Kurczy&#324;ska, E., P&#322;achno, B. J., Kozieradzka-Kiszkurno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+symplasmic+domains+in+the+embryo+and+seed+of+Sedum+acre+L.+(Crassulaceae).">Identification of symplasmic domains in the embryo and seed of Sedum acre L. (Crassulaceae).</a> Planta. 245 (3), 491-505 (2017).</li><li>Liang, D., White, R. G., Waterhouse, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+silencing+in+Arabidopsis+spreads+from+the+root+to+the+shoot,+through+a+gating+barrier,+by+template-dependent,+non-vascular,+cell+to+cell+movement.">Gene silencing in Arabidopsis spreads from the root to the shoot, through a gating barrier, by template-dependent, non-vascular, cell to cell movement.</a> Plant Physiology. 159 (3), 984-1000 (2012).</li><li>Radford, J. E., White, R. G. <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+tissue-preparation-induced+callose+synthesis+on+estimates+of+plasmodesma+size+exclusion+limits.">Effects of tissue-preparation-induced callose synthesis on estimates of plasmodesma size exclusion limits.</a> Protoplasma. 216 (1-2), 47-55 (2001).</li><li>Kollist, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+Responses+to+Abiotic+Stress:+Priming+the+Landscape+for+the+Signal+Transduction+Network.">Rapid Responses to Abiotic Stress: Priming the Landscape for the Signal Transduction Network.</a> Trends in Plant Science. 24 (1), 25-37 (2019).</li><li>Haupt, S., Duncan, G. H., Holzberg, S., Oparka, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+Symplastic+Phloem+Unloading+in+Sink+Leaves+of+Barley.">Evidence for Symplastic Phloem Unloading in Sink Leaves of Barley.</a> Plant Physiology. 125 (1), 209-218 (2001).</li><li>Botha, C. E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+xylem+sap+retrieval+pathway+in+rice+leaf+blades:+evidence+of+a+role+for+endocytosis?.">A xylem sap retrieval pathway in rice leaf blades: evidence of a role for endocytosis?.</a> Journal of Experimental Botany. 59 (11), 2945-2954 (2008).</li></ol>

The authors have nothing to disclose.

Emerging studies have shown that plants can rapidly respond to external stimuli23, including manipulation introduced to the experimental procedures22. In our initial experiment, our oversight of this knowledge often leads to staining failure. With these lessons, we suggest that the following precautions should be kept in mind when performing this experiment: (1) the seeds after harvest should be kept in a storage cabinet set to a low temperature and low moisture; (2) manipulation of plants, particularly the exposure to air in the cabinet, should be kept to a minimum time; (3) the experimental conditions should be kept constant, e.g., all the procedures should be performed in a growth room.
Another aspect in this experiment that needs to be pointed out is that the loading volume of CFDA should be kept as small as possible. Excess solution often leads to artifacts in which the excess CFDA solution can diffuse up to the shoot through capillary action, thereby tinting the trichomes of young sink leaves. Although a washing step before imaging can diminish this artifact, the best approach is to load a minimum amount to avoid complication caused by excess solution.
With these technical precautions resolved, the root-to-shoot movement of CFDA can be stably observed as shown in Figure 2. When plants grow older, say over 24 days, the Arabidopsis plants seem to lose the ability to transmit CF to the shoot, for which we have not yet found an exact explanation. One possible clue comes from its intracellular accumulation. According to the reports by Wright et al.2, CF is liable to be sequestrated by vacuoles, therefore, the intracellular free CF over the course of translocation reduces gradually to sequestration in the larger vacuoles of aging plants.
One obvious feature of this procedure is the distribution pattern of CF in the shoot. This vascular pattern is reminiscent of those by loading the dye in the source leaf1,24,25, thus leading to an illusion that the dye also moves through the phloem. In fact, the bottom-to-top translocation of CF may not be achieved through the phloem given the fact that the root is a strong sink tissue and the shootward movement of CFDA goes against phloem streaming. Rather, this process may be facilitated by xylem transport as shown by Botha et al.25. Briefly, CFDA can be taken up through xylem vessels, processed in parenchyma cells and further translocated to the sieve element of phloem stream25. Therefore, the loading experiment in this way may not reflect the activity of phloem, but the symplastic movement of CF must occur as the strong fluorescence can be detected. In other words, this bottom-to-top CF movement may result from the combined xylem transport and symplastic transport through parenchyma cells.
Symplastic transport is often subject to symplastic domain formation13, and in certain circumstances it displays unidirectional transport19,20. One way for a quick check is to shift loading sites. Indeed, when we elaborated this process using the same method, we found the simple change of loading site, from root side to the hypocotyl side proximal to root-hypocotyl junction, would result in significant change of CFDA mobile efficiency (Figure 3). The CF mobile differentiation due to the distinct loading sites would suggest that the root-hypocotyl junction is another symplastic domain, where the symplastic barrier is formed for the root-derived shootward signals. Further experimental design with other molecules is needed to explore this possibility.
So far, this simple method can provide stable shootward movement of CFDA. This feature can be further explored to distinguish plants with compromised or enhanced root-to-shoot movement which has seldom been studied.

Many fluorescent tracers with a range of spectral properties, such as 5(6)-carboxyfluorescein (CF)1, 8-hydroxypyrene-1,3,6-trisulphonic acid2, Lucifer yellow CH (LYCH)3, Esculin and CTER4, have been developed and applied in plants to monitor symplastic movement and phloem activity. Generally, a symplastic dye is loaded into a cut in the target tissue and the sequential dispersion of the reporter into other parts of plant will demonstrate the intercellular communication. Although the mechanism of dye absorption is not fully understood, the principle underlying CF movement inside live cells has been widely acknowledged. The ester form of CF (CF diacetate, CFDA) is non-fluorescent, but membrane-permeable. This property allows rapid membrane diffusion of the dye into cells. Once inside live cells, intracellular esterases remove the acetate groups at the 3&#39; and 6&#39; position of CFDA, releasing the fluorescent and membrane-impermeable CF (Figure 1, alternatively refer Wright et al.2); CF can then move through the plasmodesmata to other parts of plants.
A well-established procedure with CFDA is that it can be loaded into source leaves and used to monitor the phloem streaming and phloem unloading in the sink tissues of many species, e.g., as CF unloading in the Arabidopsis root5, phloem unloading during potato tuberization6, phloem unloading in the Nicotiana sink leaves7, and so on. By similar loading approaches, other studies have adopted this dye to demonstrate the symplastic connection between host and parasite8,9, or to reveal the symbiotic relationships10,11.
Another way to make use of this dye is to load it into specific cells or single cell by microinjection to determine its distribution pattern. Such sophisticated techniques have greatly facilitated our deeper understanding of plasmodesmata-mediated intercellular communication, particularly in the development of the concept of symplastic domain12,13. For example, the microinjection of CFDA into cotyledon cells of Arabidopsis resulted in the dye-coupling pattern in the hypocotyl epidermis but non-coupling in the underlying cells or in the root epidermis, therefore the hypocotyl epidermis forms a symplastic domain14. Similar domains, such as the stomatal guard cells15, sieve element-companion cells16, root hair cells14 and root cap17,18 have been identified by microinjection technique. Most surprisingly, some domains allow tracer molecules to move in a certain direction. Take the trichome domain for example, microinjection of a fluorescent probe into the supporting epidermal cell leads to the flow of tracer into the trichome domain, however, the reverse injection does not hold true19. A recent report has also found similar situations in the symplastic domains of the Sedum embryo20. Thus, all above cases imply that swapping of loading sites may lead to novel insights into symplastic communication. Our previous experiment aiming to dissect the route of root-to-shoot mobile silencing identified a novel symplastic domain, or the HEJ (Hypocotyl-epicotyl junction) zone, which was further verified through the root-loading (non-canonical sink-loading) CFDA experiment21. Here, we further elaborate the root-to-shoot CF movement by using a simple method and recover a potential symplastic domain by shifting the loading sites. Furthermore, this procedure may be adapted to differentiate genetic backgrounds that have altered root-to-shoot long-distance transport.

<table border="0" cellpadding="0" cellspacing="0" style="width:705px;" width="705">
	<tbody>
		<tr height="24">
			<td height="24" style="height:24px;width:223px;">KNO3&#160;&#160;</td>
			<td style="width:153px;">Sinopharm Chemical Reagent</td>
			<td style="width:127px;">10017218</td>
			<td style="width:203px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">KH2PO4&#160;</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10017608</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">MgSO4&#183;7H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10013018</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">CaCl2&#183;2H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>20011160</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">MnSO4&#183;H2O&#160;</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10013418</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Na2MoO4&#183;2H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10019818</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Boric Acid</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10004818</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">ZnSO4&#183;7H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10024018</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">CuSO4&#183;5H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10008218</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">CoCl2&#183;6H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10007216</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">KI</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10017160</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">FeSO4&#183;7H2O</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10012118</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA&#160;</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10009717</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaOH</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10019718</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">KOH</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10017018</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sucrose</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10021418</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Myo-inositol&#160;&#160;</td>
			<td>MACKLIN</td>
			<td>I811835</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nicotinic Acid&#160;</td>
			<td>MACKLIN</td>
			<td>N814565</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pyridoxine HCl</td>
			<td>MACKLIN</td>
			<td>V820447</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thiamine HCl</td>
			<td>MACKLIN</td>
			<td>T818865</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glycine</td>
			<td>MACKLIN</td>
			<td>G800880</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agar powder</td>
			<td>Novon</td>
			<td>ZZ14022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fluorescence Microscope</td>
			<td>Zeiss</td>
			<td>Axio Zoom V16</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dissecting microscope</td>
			<td>SDPTOP</td>
			<td>SRE-1030</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">200&#956;l pipette</td>
			<td>Dragon Laboratory Instruments</td>
			<td colspan="2">713111110000-20-200ul</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2.5&#956;l pipette</td>
			<td>Eppendorf</td>
			<td>3120000011</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fine forceps&#160;</td>
			<td>TWEEZERS</td>
			<td>ST-15</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Parafilm</td>
			<td>PARAFILM</td>
			<td>PM-996</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stainless steel double-sided blade</td>
			<td>Gillette</td>
			<td colspan="2">Platinum-Plus Double-Edge Blade</td>
		</tr>
	</tbody>
</table>

shootward movement of cfda tracer loaded in the bottom sink tissues of arabidopsis

The symplastic tracer 5(6)-carboxyfluorescein diacetate (CFDA) has been widely applied in living plants to demonstrate the intercellular connection, phloem transport and vascular patterning. This protocol shows bottom-to-top carboxyfluorescein (CF) movement in the Arabidopsis by using the root-cutting and the hypocotyl-pinching procedure respectively. These two different procedures result in different efficiencies of CF movement: about 91% appearance of CF in the shoots with the hypocotyl-pinching procedure, whereas only about 70% appearance of CF with the root-cutting procedure. The simple change of loading sites, resulting in significant changes in the mobile efficiency of this symplastic dye, suggests CF movement might be subject to the symplastic regulation, most probably by the root-hypocotyl junction.

Symplastic movement is often subject to environmental fluctuations. Perturbation of the plant growing state, and even the process of tissue preparation will affect the size exclusion limit of plasmodesmata, thus affecting the symplastic transport22. To improve the staining efficiency, we confine our operation in the growth room, where the temperature and moisture is tightly controlled, and also perform the whole procedure as quickly as possible (ideally within 10-15 min after lifting the lid of Petri dish). These precautions during an experiment can effectively reduce the rates of unsuccessful shoot staining.
We described two slightly different procedures to demonstrate CF shoot-ward movement. Normally, both procedures can lead to CF staining in the shoots about 2 h after feeding (Figure 2). Nevertheless, the two procedures produce different staining efficiencies. The hypocotyl-pinching procedure results in 91% staining efficiency, whereas the root-cutting procedure produces 70% (Welch&#39;s t-test, p &#60; 0.001) (Figure 3). We also tried loading the dye by a root-pinching method and found an even lower staining efficiency compared with root-cutting method, suggesting that the approach to load the dye in the root does not account for the staining difference between the root and hypocotyl loading sites (Figure 3). The CF signal is mainly found in the vasculature, but only few plants show the half-leaf pattern (Figure 2) as seen in other macromolecule movement patterns21. Once the CF signal is spread to the shoot, it can be maintained for more than 72 h and the signal cannot unload further to other cell types; this is consistent with previously published results17.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/59606/59606fig1.jpg" /> 
Figure 1: A schematic illustration for CFDA uptake and CF movement in the plant&#39;s cells. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59606/59606fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/59606/59606fig2.jpg" /> 
Figure 2: CF signal in the shoots of 9, 11 and 13 day after sowing (DAS) Arabidopsis plants. CF signal can be detected in both cotyledons and true leaves (A, B, C). In the majority of plants, the CF signal is observed in the vasculature after 2-3 hours of loading with either the root-cutting or hypocotyl-pinching method. Only in a very rare cases (less than 0.5%), the hypocotyl-pinching method can generate a partial staining pattern in the cotyledon of 7 DAS Arabidopsis (D). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59606/59606fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/59606/59606fig3.jpg" /> 
Figure 3: The staining efficiencies with the root-loading method (root-cutting and root-pinching) and hypocotyl-pinching method. The staining efficiency in 9 DAS plants was determined in three independent experiments (n = 26 in the root-pinching experiment; n = 335 in the root-cutting experiment; n = 522 in the hypocotyl-pinching method). Error bar indicates standard error. *** indicates p &#60; 0.001. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59606/59606fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Shootward Movement of CFDA Tracer Loaded in the Bottom Sink Tissues of Arabidopsis at JoVE.com

Shootward Movement of CFDA Tracer Loaded in the Bottom Sink Tissues of Arabidopsis

The goal of this protocol is to show how to load the CFDA into different sites of the bottom parts of Arabidopsis. We then present the resulting distribution pattern of CF in the shoots.

Shootward Movement of CFDA Tracer Loaded in the Bottom Sink Tissues of Arabidopsis

The symplastic tracer 5(6)-carboxyfluorescein diacetate (CFDA) has been widely applied in living plants to demonstrate the intercellular connection, ...

shootward-movement-cfda-tracer-loaded-bottom-sink-tissues

Nanyang Technological University

Research

JoVE Journal

Environment

6.6K Views.  Yangtze University. The goal of this protocol is to show how to load the CFDA into different sites of the bottom parts of Arabidopsis. We then present the resulting distribution pattern of CF in the shoots.

Video: Shootward Movement of CFDA Tracer Loaded in the Bottom Sink Tissues of Arabidopsis

Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays

Much of the nutrient cycling and carbon processing in natural environments occurs through the activity of extracellular enzymes released by microorganisms. Thus, measurement of the activity of these extracellular enzymes can give insights into the rates of ecosystem level processes, such as organic matter decomposition or nitrogen and phosphorus mineralization. Assays of extracellular enzyme activity in environmental samples typically involve exposing the samples to artificial colorimetric or fluorometric substrates and tracking the rate of substrate hydrolysis. Here we describe microplate based methods for these procedures that allow the analysis of large numbers of samples within a short time frame. Samples are allowed to react with artificial substrates within 96-well microplates or deep well microplate blocks, and enzyme activity is subsequently determined by absorption or fluorescence of the resulting end product using a typical microplate reader or fluorometer. Such high throughput procedures not only facilitate comparisons between spatially separate sites or ecosystems, but also substantially reduce the cost of such assays by reducing overall reagent volumes needed per sample.

Microplate based procedures are described for the colorimetric or fluorometric analysis of extracellular enzyme activity. These procedures allow for the rapid assay of such activity in large numbers of environmental samples within a manageable time frame.

Much of the nutrient cycling and carbon  processing in natural environments occurs through the activity of extracellular  enzymes released by ...

Technique for Studying Arthropod and Microbial Communities within Tree Tissues

Phloem tissues of pine are habitats for many thousands of organisms. Arthropods and microbes use phloem and cambium tissues to seek mates, lay eggs, rear young, feed, or hide from natural enemies or harsh environmental conditions outside of the tree. Organisms that persist within the phloem habitat are difficult to observe given their location under bark. We provide a technique to preserve intact phloem and prepare it for experimentation with invertebrates and microorganisms. The apparatus is called a &#8216;phloem sandwich&#8217; and allows for the introduction and observation of arthropods, microbes, and other organisms. This technique has resulted in a better understanding of the feeding behaviors, life-history traits, reproduction, development, and interactions of organisms within tree phloem. The strengths of this technique include the use of inexpensive materials, variability in sandwich size, flexibility to re-open the sandwich or introduce multiple organisms through drilled holes, and the preservation and maintenance of phloem integrity. The phloem sandwich is an excellent educational tool for scientific discovery in both K-12 science courses and university research laboratories.

We provide a technique to preserve intact tree phloem and prepare it for observation. We create an apparatus called a phloem sandwich that allows for the introduction and observation of arthropods, microbes, and other organisms that inhabit phloem tissues.

Phloem tissues of pine are habitats for many thousands of organisms.  Arthropods and microbes use phloem and cambium tissues to seek mates, lay eggs, rear ...

A Fish-feeding Laboratory Bioassay to Assess the Antipredatory Activity of Secondary Metabolites from the Tissues of Marine Organisms

Marine chemical ecology is a young discipline, having emerged from the collaboration of natural products chemists and marine ecologists in the 1980s with the goal of examining the ecological functions of secondary metabolites from the tissues of marine organisms. The result has been a progression of protocols that have increasingly refined the ecological relevance of the experimental approach. Here we present the most up-to-date version of a fish-feeding laboratory bioassay that enables investigators to assess the antipredatory activity of secondary metabolites from the tissues of marine organisms. Organic metabolites of all polarities are exhaustively extracted from the tissue of the target organism and reconstituted at natural concentrations in a nutritionally appropriate food matrix. Experimental food pellets are presented to a generalist predator in laboratory feeding assays to assess the antipredatory activity of the extract. The procedure described herein uses the bluehead, Thalassoma bifasciatum, to test the palatability of Caribbean marine invertebrates; however, the design may be readily adapted to other systems. Results obtained using this laboratory assay are an important prelude to field experiments that rely on the feeding responses of a full complement of potential predators. Additionally, this bioassay can be used to direct the isolation of feeding-deterrent metabolites through bioassay-guided fractionation. This feeding bioassay has advanced our understanding of the factors that control the distribution and abundance of marine invertebrates on Caribbean coral reefs and may inform investigations in diverse fields of inquiry, including pharmacology, biotechnology, and evolutionary ecology.

This bioassay employs a model predatory fish to assess the presence of feeding-deterrent metabolites from organic extracts of the tissues of marine organisms at natural concentrations using a nutritionally comparable food matrix.

Marine chemical ecology is a young discipline, having emerged from the collaboration of natural products chemists and marine ecologists in the 1980s with ...

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current measures to combat such pathogens have proved too conservative and, thus, not sufficiently effective, and they can potentially pose environmental risks. Therefore, it is extremely necessary to identify host-resistance factors to assist in controlling plant diseases naturally through the identification of resistant germplasm, the isolation and characterization of resistance genes, and the molecular breeding of resistant cultivars. In this regard, there is need to establish an accurate, rapid, and large-scale inoculation method to breed and develop plant resistance genes. The rice blast fungal pathogen Magnaporthe grisea causes severe disease symptoms and yield losses. Recently, M. grisea has emerged as a model organism for studying the mechanisms of plant-fungal pathogen interactions. Hence, we report the development of a plant virulence test method that is specific for M. grisea. This method provides for both spray inoculation with a conidial suspension and wounding inoculation with mycelium cubes or droplets of conidial suspension. The key step of the wounding inoculation method for detached rice leaves is to make wounds on plant leaves, which avoids any interference caused by host penetration resistance. This spray/wounding protocol contributes to the rapid, accurate, and large-scale screening of the pathotypes of M. grisea isolates. This integrated and systematic plant infection method will serve as an excellent starting point for gaining a broad perspective of issues in plant pathology.

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Here, we present a protocol to test plant virulence with the plant pathogen Magnaporthe grisea. This report will contribute to the large-scale screening of the pathotypes of fungi isolates and serve as an excellent starting point for understanding the resistant mechanisms of plants during molecular breeding.

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current ...

Use of Autometallography to Localize and Semi-Quantify Silver in Cetacean Tissues

Silver nanoparticles (AgNPs) have been extensively used in commercial products, including textiles, cosmetics, and health care items, due to their strong antimicrobial effects. They also may be released into the environment and accumulate in the ocean. Therefore, AgNPs are the major source of Ag contamination, and public awareness of the environmental toxicity of Ag is increasing. Previous studies have demonstrated the bioaccumulation (in producers) and magnification (in consumers/predators) of Ag. Cetaceans, as the apex predators of ocean, may have been negatively affected by the Ag/Ag compounds. Although the concentrations of Ag/Ag compounds in cetacean tissues can be measured by inductively coupled plasma mass spectroscopy (ICP-MS), the use of ICP-MS is limited by its high capital cost and the requirement for tissue storage/preparation. Therefore, an autometallography (AMG) method with an image quantitative analysis by using formalin-fixed, paraffin-embedded (FFPE) tissue may be an adjuvant method to localize Ag distribution at the suborgan level and estimate the Ag concentration in cetacean tissues. The AMG positive signals are mainly brown to black granules of various sizes in the cytoplasm of proximal renal tubular epithelium, hepatocytes, and Kupffer cells. Occasionally, some amorphous golden yellow to brown AMG positive signals are noted in the lumen and basement membrane of some proximal renal tubules. The assay for estimating the Ag concentration is named the Cetacean Histological Ag Assay (CHAA), which is a regression model established by the data from image quantitative analysis of the AMG method and ICP-MS. The use of AMG with CHAA to localize and semi-quantify heavy metals provides a convenient methodology for spatio-temporal and cross-species studies.

A protocol is presented to localize Ag in cetacean liver and kidney tissues by autometallography. Furthermore, a new assay, named the cetacean histological Ag assay (CHAA) is developed to estimate the Ag concentrations in those tissues.

Silver nanoparticles (AgNPs) have been extensively used in commercial products, including textiles, cosmetics, and health care items, due to their strong ...

An Induction System for Clustered Stomata by Sugar Solution Immersion Treatment in Arabidopsis thaliana Seedlings

Stomatal movement mediates plant gas exchange, which is essential for photosynthesis and transpiration. Stomatal opening and closing are accomplished by a significant increase and decrease in guard cell volume, respectively. Because shuttle transport of ions and water occurs between guard cells and larger neighboring epidermal cells during stomatal movement, the spaced distribution of plant stomata is considered an optimal distribution for stomatal movement. Experimental systems for perturbing the spaced pattern of stomata are useful to examine the spacing pattern's significance. Several key genes associated with the spaced stomatal distribution have been identified, and clustered stomata can be experimentally induced by altering these genes. Alternatively, clustered stomata can be also induced by exogenous treatments without genetic modification. In this article, we describe a simple induction system for clustered stomata in Arabidopsis thaliana seedlings by immersion treatment with a sucrose-containing medium solution. Our method is easy and directly applicable to transgenic or mutant lines. Larger chloroplasts are presented as a cell biological hallmark of sucrose-induced clustered guard cells. In addition, a representative confocal microscopic image of cortical microtubules is shown as an example of intracellular observation of clustered guard cells. The radial orientation of cortical microtubules is maintained in clustered guard cells as in spaced guard cells in control conditions.

An Induction System for Clustered Stomata by Sugar Solution Immersion Treatment in Arabidopsis thaliana Seedlings

The goal of this protocol is to demonstrate how to induce clustered stomata in cotyledons of Arabidopsis thaliana seedlings by immersion treatment with a sugar-containing medium solution and how to observe intracellular structures such as chloroplasts and microtubules in the clustered guard cells using confocal laser microscopy.

Stomatal movement mediates plant gas exchange, which is essential for photosynthesis and transpiration. Stomatal opening and closing are accomplished by a ...

Fluorescently Labeled Bacteria as a Tracer to Reveal Novel Pathways of Organic Carbon Flow in Aquatic Ecosystems

Elucidating trophic interactions, such as predation and its effects, is a frequent task for many researchers in ecology. The study of microbial communities has many limitations, and determining a predator, prey, and predatory rates is often difficult. Presented here is an optimized method based on the addition of fluorescently labelled prey as a tracer, which allows for reliable quantitation of the grazing rates in aquatic predatory eukaryotes and estimation of nutrient transfer to higher trophic levels.

Presented here is a protocol for a single-cell, epifluorescence microscopy-based technique to quantify grazing rates in aquatic predatory eukaryotes with high precision and taxonomic resolution.

Elucidating trophic interactions, such as predation and its effects, is a frequent task for many researchers in ecology. The study of microbial ...

A Telemetric, Gravimetric Platform for Real-Time Physiological Phenotyping of Plant&ndash;Environment Interactions

Food security for the growing global population is a major concern. The data provided by genomic tools far exceeds the supply of phenotypic data, creating a knowledge gap. To meet the challenge of improving crops to feed the growing global population, this gap must be bridged.
Physiological traits are considered key functional traits in the context of responsiveness or sensitivity to environmental conditions. Many recently introduced high-throughput (HTP) phenotyping techniques are based on remote sensing or imaging and are capable of directly measuring morphological traits, but measure physiological parameters mainly indirectly.
This paper describes a method for direct physiological phenotyping that has several advantages for the functional phenotyping of plant&#8211;environment interactions. It helps users overcome the many challenges encountered in the use of load-cell gravimetric systems and pot experiments. The suggested techniques will enable users to distinguish between soil weight, plant weight and soil water content, providing a method for the continuous and simultaneous measurement of dynamic soil, plant and atmosphere conditions, alongside the measurement of key physiological traits. This method allows researchers to closely mimic field stress scenarios while taking into consideration the environment&#8217;s effects on the plants&#8217; physiology. This method also minimizes pot effects, which are one of the major problems in pre-field phenotyping. It includes a feed-back fertigation system that enables a truly randomized experimental design at a field-like plant density. This system detects the soil-water-content limiting threshold (&#952;) and allows for the translation of data into knowledge through the use of a real-time analytic tool and an online statistical resource. This method for the rapid and direct measurement of the physiological responses of multiple plants to a dynamic environment has great potential for use in screening for beneficial traits associated with responses to abiotic stress, in the context of pre-field breeding and crop improvement.

A Telemetric, Gravimetric Platform for Real-Time Physiological Phenotyping of Plant&#8211;Environment Interactions

This high-throughput, telemetric, whole-plant water relations gravimetric phenotyping method enables direct and simultaneous real-time measurements, as well as the analysis of multiple yield-related physiological traits involved in dynamic plant&#8211;environment interactions.

Food security for the growing global population is a major concern. The data provided by genomic tools far exceeds the supply of phenotypic data, creating ...

Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the emergence of life. The growth of hydrothermal chimneys in a thermal gradient environment within an early Earth vent system was successfully simulated by using different hydrothermal simulants, such as sodium sulfide, which were injected into an early Earth ocean simulant containing dissolved ferrous iron. Moreover, an apparatus was developed to sufficiently cool the ocean simulant to near 0 &#176;C in a condenser vessel immersed in a cold water bath while injecting a sulfide solution at hot to room temperatures, effectively creating an artificial chimney structure in a temperature gradient environment over a period of a few hours. Such experiments with different chemistries and variable temperature&#160;gradients resulted in a variety of morphologies in the chimney structure. The use of ocean and hydrothermal fluid simulants at room temperature resulted in vertical chimneys, whereas the combination of a hot hydrothermal fluid and cold ocean simulant inhibited the formation of robust chimney structures. The customizable 3D printed condenser created for this study acts as a jacketed reaction vessel that can be easily modified and used by different researchers. It will allow the careful control of injection rate and chemical composition of vent and ocean simulants, which should help accurately simulate prebiotic reactions in chimney systems with thermal gradients similar to those of natural systems.

The goal of this protocol is to form simulated hydrothermal chimneys via chemical garden injection experiments and introduce a thermal gradient across the inorganic precipitate membrane, using a 3D printable condenser that can be reproduced for educational purposes.

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the ...

The Role of Fabric in Frictional Properties of Phyllosilicate-Rich Tectonic Faults

Many rock deformation experiments used to characterize the frictional properties of tectonic faults are performed on powdered fault rocks or on bare rock surfaces. These experiments have been fundamental to document the frictional properties of granular mineral phases and provide evidence for crustal faults characterized by high friction. However, they cannot entirely capture the frictional properties of faults rich in phyllosilicates.
Numerous studies of natural faults have documented fluid-assisted reaction softening promoting the replacement of strong minerals with phyllosilicates that are distributed into continuous foliations. To study how these foliated fabrics influence the frictional properties of faults we have: 1) collected foliated phyllosilicate-rich rocks from natural faults; 2) cut the fault rock samples to obtain solid wafers 0.8-1.2 cm thick and 5 cm x 5 cm in area with the foliation parallel to the 5x5cm face of the wafer; 3) performed friction tests on both solid wafers sheared in their in situ geometry and powders, obtained by crushing and sieving and therefore disrupting the foliation of the same samples; 4) recovered the samples for microstructural studies from the post experiment rock samples; and 5) performed microstructural analyses via optical microscopy, scanning and transmission electron microscopy. 
Mechanical data show that the solid samples with well-developed foliation show significantly lower friction in comparison to their powdered equivalents. Micro- and nano-structural studies demonstrate that low friction results from sliding along the foliation surfaces composed of phyllosilicates. When the same rocks are powdered, frictional strength is high, because sliding is accommodated by fracturing, grain rotation, translation and associated dilation. Friction tests indicate that foliated fault rocks may have low friction even when phyllosilicates constitute only a small percentage of the total rock volume, implying that a significant number of crustal faults are weak.

Friction of phyllosilicates-rich faults sheared in their in situ geometry is significantly lower than friction of their powdered equivalents.

Many rock deformation experiments used to characterize the frictional properties of tectonic faults are performed on powdered fault rocks or on bare rock ...

Shootward Movement of CFDA Tracer Loaded in the Bottom Sink Tissues of Arabidopsis

Summary

Explore More Videos

Chapters in this video

Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays

Technique for Studying Arthropod and Microbial Communities within Tree Tissues

A Fish-feeding Laboratory Bioassay to Assess the Antipredatory Activity of Secondary Metabolites from the Tissues of Marine Organisms

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Use of Autometallography to Localize and Semi-Quantify Silver in Cetacean Tissues

An Induction System for Clustered Stomata by Sugar Solution Immersion Treatment in Arabidopsis thaliana Seedlings

Fluorescently Labeled Bacteria as a Tracer to Reveal Novel Pathways of Organic Carbon Flow in Aquatic Ecosystems

A Telemetric, Gravimetric Platform for Real-Time Physiological Phenotyping of Plant–Environment Interactions

Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

The Role of Fabric in Frictional Properties of Phyllosilicate-Rich Tectonic Faults