We are grateful to the E. coli stock center for MG1693; Wormbase; the Caenorhabditis Genetics Center which is funded by the National Institutes of Health Office of Research Infrastructure Programs (P40OD010440) for strains; Zach Pincus for statistical advice; Aiping Feng for reagents; Luke Schneider, Andrea Scharf, Sandeep Kumar, and John Brenner for training, advice, support, and helpful discussion; and the Kornfeld and Schedl labs for feedback on this manuscript. This work was supported in part by National Institutes of Health [R01 AG02656106A1 to KK, R01 GM100756 to TS] and a National Science Foundation predoctoral fellowship [DGE-1143954 and DGE-1745038 to ZK]. Neither the National Institutes of Health nor the National Science Foundation had any role in the design of the study, collection, analysis, and interpretation of data, nor in writing the manuscript.

1. Preparation of EdU-labeled Bacteria
<ol>
	<li>Grow a starter culture of MG1693. Escherichia coli (E. coli) MG1693 carries a mutation in thyA.
	<ol>
		<li>Streak out E. coli MG1693 from a frozen glycerol stock onto a 120 mm lysogeny broth (LB) agar Petri dish. Culture at 37 &#176;C overnight.</li>
		<li>Inoculate from two individual E. coli MG1693 colonies into two duplicate 4 mL tubes of liquid LB. Culture at 37 &#176;C for ~16 h. 
		NOTE: MG1693 grows fine i...

<ol>
	<li>Fox, P. M., Vought, V. E., Hanazawa, M., Lee, M. -. H., Maine, E. M., Schedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclin+E+and+CDK-2+regulate+proliferative+cell+fate+and+cell+cycle+progression+in+the+C.+elegans+germline.">Cyclin E and CDK-2 regulate proliferative cell fate and cell cycle progression in the C. elegans germline.</a> Development. 138 (11), 2223-2234 (2011).</li><li>Crittenden, S. L., Leonhard, K. A., Byrd, D. T., Kimble, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+analyses+of+the+mitotic+region+in+the+Caenorhabditis+elegans+adult+germ+line.">Cellular analyses of the mitotic region in the Caenorhabditis elegans adult germ line.</a> Molecular biology of the cell. 17 (7), 3051-3061 (2006).</li><li>Seidel, H. S., Kimble, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-cycle+quiescence+maintains+Caenorhabditis+elegans+germline+stem+cells+independent+of+GLP-1/Notch.">Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch.</a> eLife. 4, (2015).</li><li>Fox, P. M., Schedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+Germline+Stem+Cell+Differentiation+Following+Loss+of+GLP-1+Notch+Activity+in+Caenorhabditis+elegans.">Analysis of Germline Stem Cell Differentiation Following Loss of GLP-1 Notch Activity in Caenorhabditis elegans.</a> Genetics. 201 (9), 167-184 (2015).</li><li>Kocsisova, Z., Kornfeld, K., Schedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+cycle+accumulation+of+the+proliferating+cell+nuclear+antigen+PCN-1+transitions+from+continuous+in+the+adult+germline+to+intermittent+in+the+early+embryo+of+C.+elegans.">Cell cycle accumulation of the proliferating cell nuclear antigen PCN-1 transitions from continuous in the adult germline to intermittent in the early embryo of C. elegans.</a> BMC Developmental Biology. 18 (1), (2018).</li><li>Salic, A., Mitchison, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+chemical+method+for+fast+and+sensitive+detection+of+DNA+synthesis+in+vivo.">A chemical method for fast and sensitive detection of DNA synthesis in vivo.</a> Proceedings of the National Academy of Sciences. 105 (7), 2415-2420 (2008).</li><li>vanden Heuvel, S., Kipreos, E. T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=elegans+Cell+Cycle+Analysis.">elegans Cell Cycle Analysis.</a> Methods in Cell Biology. , 265-294 (2012).</li><li>ThermoFisher. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Click-iT EdU Imaging Kits. , (2011).</li><li>Pazdernik, N., Schedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Germ Cell Development in C. elegans. , 1-16 (2013).</li><li>Hirsh, D., Oppenheim, D., Klass, M. <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+the+reproductive+system+of+Caenorhabditis+elegans.">Development of the reproductive system of Caenorhabditis elegans.</a> Developmental Biology. 49 (1), 200-219 (1976).</li><li>Brenner, 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+genetics+of+Caenorhabditis+elegans.">The genetics of Caenorhabditis elegans.</a> Genetics. 77 (1), 71-94 (1974).</li><li>Hansen, D., Schedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cell+proliferation+versus+meiotic+fate+decision+in+Caenorhabditis+elegans.">Stem cell proliferation versus meiotic fate decision in Caenorhabditis elegans.</a> Advances in Experimental Medicine and Biology. 757, 71-99 (2013).</li><li>Jaramillo-Lambert, A., Ellefson, M., Villeneuve, A. M., Engebrecht, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+timing+of+S+phases,+X+chromosome+replication,+and+meiotic+prophase+in+the+C.+elegans+germ+line.">Differential timing of S phases, X chromosome replication, and meiotic prophase in the C. elegans germ line.</a> Developmental Biology. 308 (1), 206-221 (2007).</li><li>Agarwal, I., Farnow, C., 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=HOP-1+presenilin+deficiency+causes+a+late-onset+notch+signaling+phenotype+that+affects+adult+germline+function+in+Caenorhabditis+elegans.">HOP-1 presenilin deficiency causes a late-onset notch signaling phenotype that affects adult germline function in Caenorhabditis elegans.</a> Genetics. 208 (2), 745-762 (2018).</li><li>Gumienny, T. L., Lambie, E., Hartwieg, E., Horvitz, H. R., Hengartner, M. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+control+of+programmed+cell+death+in+the+Caenorhabditis+elegans+hermaphrodite+germline.">Genetic control of programmed cell death in the Caenorhabditis elegans hermaphrodite germline.</a> Development. 126 (5), 1011-1022 (1999).</li><li>Hendzel, M. J., Wei, Y., 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=Mitosis-specific+phosphorylation+of+histone+H3+initiates+primarily+within+pericentromeric+heterochromatin+during+G2+and+spreads+in+an+ordered+fashion+coincident+with+mitotic+chromosome+condensation.">Mitosis-specific phosphorylation of histone H3 initiates primarily within pericentromeric heterochromatin during G2 and spreads in an ordered fashion coincident with mitotic chromosome condensation.</a> Chromosoma. 106 (6), 348-360 (1997).</li><li>Zetka, M. C., Kawasaki, I., Strome, S., M&#252; Ller, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synapsis+and+chiasma+formation+in+Caenorhabditis+elegans+require+HIM-3,+a+meiotic+chromosome+core+component+that+functions+in+chromosome+segregation.">Synapsis and chiasma formation in Caenorhabditis elegans require HIM-3, a meiotic chromosome core component that functions in chromosome segregation.</a> Genes &amp; development. 13 (17), 2258-2270 (1999).</li><li>Hansen, D., Hubbard, E. J. A., Schedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-pathway+control+of+the+proliferation+versus+meiotic+development+decision+in+the+Caenorhabditis+elegans+germline.">Multi-pathway control of the proliferation versus meiotic development decision in the Caenorhabditis elegans germline.</a> Developmental Biology. 268 (2), 342-357 (2004).</li><li>Crawley, O., Barroso, C., 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=Cohesin-interacting+protein+WAPL-1+regulates+meiotic+chromosome+structure+and+cohesion+by+antagonizing+specific+cohesin+complexes.">Cohesin-interacting protein WAPL-1 regulates meiotic chromosome structure and cohesion by antagonizing specific cohesin complexes.</a> eLife. 5 (2), 1-26 (2016).</li><li>Zhao, H., Halicka, H. D., 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=DNA+damage+signaling,+impairment+of+cell+cycle+progression,+and+apoptosis+triggered+by+5-ethynyl-2&#8242;-deoxyuridine+incorporated+into+DNA.">DNA damage signaling, impairment of cell cycle progression, and apoptosis triggered by 5-ethynyl-2&#8242;-deoxyuridine incorporated into DNA.</a> Cytometry Part A. 83 (11), 979-988 (2013).</li><li>Stiernagle, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maintenance+of+C.+elegans.">Maintenance of C. elegans.</a> WormBook. , 1-11 (2006).</li><li>Gervaise, A. L., Arur, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatial+and+Temporal+Analysis+of+Active+ERK.">Spatial and Temporal Analysis of Active ERK.</a> in the C. elegans Germline. Journal of Visualized Experiments. 117 (117), e54901-e54901 (2016).</li><li>Vos, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> De Cell Counter Plugin. , (2015).</li><li>Schindelin, J., Arganda-Carreras, I., 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=Fiji:+an+open-source+platform+for+biological-image+analysis.">Fiji: an open-source platform for biological-image analysis.</a> Nature Methods. 9 (7), 676-682 (2012).</li><li>Rasband, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ImageJ. , (2016).</li><li>Michaelson, D., Korta, D. Z., Capua, Y., Hubbard, E. 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=Insulin+signaling+promotes+germline+proliferation+in+C.+elegans.">Insulin signaling promotes germline proliferation in C. elegans.</a> Development. 137 (4), 671-680 (2010).</li><li>Qin, Z., Jane, E., Hubbard, A., Hubbard, E. 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=Non-autonomous+DAF-16/FOXO+activity+antagonizes+age-related+loss+of+C.+elegans+germline+stem/progenitor+cells.">Non-autonomous DAF-16/FOXO activity antagonizes age-related loss of C. elegans germline stem/progenitor cells.</a> Nature communications. 6 (5), 7107 (2015).</li><li>Luo, S., Kleemann, G. A., Ashraf, J. M., Shaw, W. M., Murphy, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGFB+and+Insulin+Signaling+Regulate+Reproductive+Aging+via+Oocyte+and+Germline+Quality+Maintenance.">TGFB and Insulin Signaling Regulate Reproductive Aging via Oocyte and Germline Quality Maintenance.</a> Cell. 143 (2), 299-312 (2010).</li><li>Narbonne, P., Maddox, P. S., Labbe, J. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=daf-18/PTEN+locally+antagonizes+insulin+signalling+to+couple+germline+stem+cell+proliferation+to+oocyte+needs+in+C.+elegans.">daf-18/PTEN locally antagonizes insulin signalling to couple germline stem cell proliferation to oocyte needs in C. elegans.</a> Development. , 4230-4241 (2015).</li><li>Cinquin, A., Chiang, 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=Intermittent+Stem+Cell+Cycling+Balances+Self-Renewal+and.">Intermittent Stem Cell Cycling Balances Self-Renewal and.</a> Senescence of the C. elegans Germ Line. PLoS Genetics. 12 (4), 1005985 (2016).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Invitrogen EdU (5-ethynyl-2’-deoxyuridine). , 1-7 (2010).</li><li>Tuttle, A. H., Rankin, M. 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=Immunofluorescent+Detection+of+Two+Thymidine+Analogues+(CldU+and+IdU)+in+Primary+Tissue.">Immunofluorescent Detection of Two Thymidine Analogues (CldU and IdU) in Primary Tissue.</a> Journal of Visualized Experiments. 46 (46), e2166-e2166 (2010).</li></ol>

Preparation of EdU-labeled bacteria (step 1) is critical for this protocol, and the first point for troubleshooting. Wild-type young adult hermaphrodites label very reliably in a 4 h EdU-pulse, making this a useful control for every new batch of EdU-labeled bacteria. Additionally, intact EdU-labeled bacteria that enter the intestine (in older animals or certain pharynx/grinder defective mutants) will label with click chemistry and appear as bright oblong puncta in the gut. An alternative technique for labeling hermaphrod...

In animal development, hundreds, thousands, millions, billions, or even trillions of cell divisions are required to form the adult organism. The cell cycle, the set of cellular events composed of G1 (gap), S (synthesis), G2 (gap), and M (mitosis) define the series of events that are executed each cell division. The cell cycle is dynamic and best appreciated in real time, which can be technically difficult. The techniques presented in this protocol allow one to make the measurements of the phases and timing of the cell cycle from still images.
Labeling with nucleoside analogs such as 5-ethynyl-2&#39;-deoxyuridine (EdU) or 5-bromo-2&#39;-deoxyuridine (BrdU) is the gold standard to identify S-phase in the studies of cell cycle dynamics in the Caenorhabditis elegans (C. elegans) adult hermaphrodite germline1,2,3,4,5. Both EdU and BrdU can be used in nearly any genetic background, as they do not rely on any genetic construct. Visualizing BrdU requires harsh chemical treatment to expose the antigen for anti-BrdU antibody staining, which is often incompatible with the assessment of other cellular markers visualized by co-staining with additional antibodies. By contrast, visualizing EdU occurs by click chemistry under mild conditions and thus is compatible with antibody co-staining6,7.
The specificity of the label is clear, since nuclei only incorporate the thymidine (5-ethynyl-2&#39;- deoxyuridine) analogs into DNA during S-phase. Visualization takes place in fixed tissue. The EdU label is invisible by itself until an azide-containing dye or fluorophore reacts covalently with the alkyne in EdU by copper-catalyzed click chemistry8. EdU labeling can provide immediate information on which nuclei are in S-phase, using a short pulse of labeling. EdU can also provide dynamic information, using pulse-chase or continuous labeling; for example, in a pulse-chase experiment, the label is diluted at each cell division or propagated as nondividing cells progress through development.
The C. elegans hermaphrodite germline is a powerful model system for the studies of signaling pathways, stem cells, meiosis, and cell cycle. The adult germline is a polarized assembly-line with stem cells found at the distal end followed by entry and progression through meiotic prophase, coordinated with the stages of gametogenesis more proximally (Figure 1). At the proximal end, oocytes mature, are ovulated and fertilized and begin embryogenesis in the uterus9,10,11. The ~20 cell-diameter long region near the distal tip cell, which includes the mitotically cycling germline stem, progenitor cells and meiotic S-phase cells but not the cells in meiotic prophase, is called the progenitor zone2,4,9,12. The cell membranes provide incomplete separation between the nuclei in the distal germline, but the progenitor zone cells undergo mitotic cell cycling largely independently. The median mitotic cell cycle duration of germline progenitor zone cells in young adult hermaphrodites is ~6.5 h; G1 phase is brief or absent, and quiescence is not observed1,2,13. Germline stem cell differentiation occurs through essentially direct differentiation and thus lacks transit-amplifying divisions4. During differentiation in the pachytene stage, approximately 4 out of 5 nuclei will not form oocytes but instead undergo apoptosis, acting as nurse cells by donating their cytoplasmic contents to the developing oocyte12,14,15.
In addition to labeling cells in S-phase with nucleoside analogs, one can identify the cells in mitosis and meiosis using antibody staining. Nuclei in mitosis are immunoreactive to anti-phospho-histone H3 (Ser10) antibody (called pH3)7,16. Nuclei in meiosis are immunoreactive to anti-HIM-3 antibody (a meiotic chromosome axis protein)17. Nuclei in the progenitor zone can be identified by the absence of HIM-3, the presence of nucleoplasmic REC-818, or the presence of WAPL-119. WAPL-1 intensity is highest in the somatic gonad, high in the progenitor zone, and low during early meiotic prophases19. Several cell cycle measurements are possible with a few variations in the protocol: I) identify nuclei in S-phase and measure S-phase index; II) Identify nuclei in M-phase and measure the M-phase index; III) determine whether nuclei were in mitotic or meiotic S-phase; IV) measure the duration of G2; V) measure the duartion&#160;of G2+M+G1 phases; VI) measure the rate of meiotic entry; VII) estimate the rate of meiotic progression.
One can make multiple cell cycle measurements from only a few types of wet-lab experiments. The protocol below describes a 30 min pulse labeling by feeding C. elegans adult hermaphrodites with EdU labeled bacteria and co-labeling M-phase cells by staining with anti-pH3 antibody and progenitor zone cells by staining with anti-WAPL-1 antibody. Only changes in the duration&#160;of EdU feed (Step 2.5), type of antibodies employed (Step 5), and analyses (Step 8.3) are required for the additional measurements.

<table border="0" cellpadding="0" cellspacing="0" style="width:1019px;" width="1020">
	<tbody>
		<tr height="42">
			<td >E. coli MG1693</td>
			<td style="width:255px;">Coli Genetic Stock Center</td>
			<td style="width:255px;">6411</td>
			<td style="width:255px;">grows fine in standard unsupplemented LB</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">E. coli OP50</td>
			<td style="width:255px;">Caenorhabditis Genetics Center</td>
			<td style="width:255px;">OP50</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Click-iT EdU Alexa Fluor 488 Imaging Kit</td>
			<td style="width:255px;">Thermo Fisher Scientific</td>
			<td style="width:255px;">C10337</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">5-Ethynyl-2&#8242;-deoxyuridine</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">900584-50MG</td>
			<td style="width:255px;">or use EdU provided in kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Glucose</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">D9434-500G</td>
			<td style="width:255px;">D-(+)-Dextrose</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Thiamine (Vitamin B1)</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">T4625-5G</td>
			<td style="width:255px;">Reagent Grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Thymidine</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">T1895-1G</td>
			<td style="width:255px;">BioReagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Magnesium sulfate heptahydrate</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">M1880-1KG</td>
			<td style="width:255px;">MgSO4, Reagent Grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Sodium Phosphate, dibasic, anhydrous</td>
			<td style="width:255px;">Fisher</td>
			<td style="width:255px;">BP332-500G</td>
			<td style="width:255px;">Na2HPO4</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Potassium Phosphate, monobasic</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">P5379-500G</td>
			<td style="width:255px;">KH2PO4</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Ammonium Chloride</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">A4514-500G</td>
			<td style="width:255px;">NH4Cl, Reagent Plus</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Bacteriological Agar</td>
			<td style="width:255px;">US Biological</td>
			<td style="width:255px;">C13071058</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Calcium Chloride dihydrate</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">C3881-500G</td>
			<td style="width:255px;">CaCl</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">LB Broth (Miller)</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">L3522-1KG</td>
			<td style="width:255px;">Used at 25g/L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Levamisole</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">L9756-5G</td>
			<td style="width:255px;">0.241g/10ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Phosphate buffered saline</td>
			<td style="width:255px;">Calbiochem Omnipur</td>
			<td style="width:255px;">6506</td>
			<td style="width:255px;">homemade PBS works just as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Tween-20</td>
			<td style="width:255px;">Sigma</td>
			<td style="width:255px;">P1379-500ML</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">16% Paraformaldehyde, EM-grade ampules</td>
			<td style="width:255px;">Electron Microscopy Sciences</td>
			<td style="width:255px;">15710</td>
			<td style="width:255px;">10ml ampules</td>
		</tr>
		<tr height="62">
			<td height="62" style="height:62px;width:255px;">100% methanol</td>
			<td style="width:255px;">Thermo Fisher Scientific</td>
			<td style="width:255px;">A454-1L</td>
			<td style="width:255px;">Gold-label methanol is critical for proper morphology with certain antibodies</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Goat Serum</td>
			<td style="width:255px;">Gibco</td>
			<td style="width:255px;">16210-072</td>
			<td style="width:255px;">Lot 1671330</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">rabbit-anti-WAPL-1</td>
			<td style="width:255px;">Novus biologicals</td>
			<td style="width:255px;">49300002</td>
			<td style="width:255px;">Lot G3048-179A02, used at 1:2000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">mouse-anti-pH3 clone 3H10</td>
			<td style="width:255px;">Millipore</td>
			<td style="width:255px;">05-806</td>
			<td style="width:255px;">Lot#2680533, used at 1:500</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">goat-anti-rabbit IgG-conjugated Alexa Fluor 594</td>
			<td style="width:255px;">Invitrogen</td>
			<td style="width:255px;">A11012</td>
			<td style="width:255px;">Lot 1256147, used at 1:400</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">goat-anti-mouse IgG-conjugated Alexa Fluor 647</td>
			<td style="width:255px;">Invitrogen</td>
			<td style="width:255px;">A21236</td>
			<td style="width:255px;">Lot 1511347, used at 1:400</td>
		</tr>
		<tr height="62">
			<td height="62" style="height:62px;width:255px;">Vectashield antifade mounting medium containing 4&#39;,6-Diamidino-2-Phenylindole Dihydrochloride (DAPI)</td>
			<td style="width:255px;">Vector Laboratories</td>
			<td style="width:255px;">H-1200</td>
			<td style="width:255px;">mounting medium without DAPI can be used instead, following a separate DAPI incubation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">nail polish</td>
			<td style="width:255px;">Wet n Wild</td>
			<td style="width:255px;">DTC450B</td>
			<td style="width:255px;">any clear nail polish should work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">S-medium</td>
			<td style="width:255px;">various</td>
			<td style="width:255px;"></td>
			<td style="width:255px;">see wormbook.org for protocol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">M9 buffer</td>
			<td style="width:255px;">various</td>
			<td style="width:255px;"></td>
			<td style="width:255px;">see wormbook.org for protocol</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">M9 agar</td>
			<td style="width:255px;">various</td>
			<td style="width:255px;"></td>
			<td style="width:255px;">same recipe as M9 buffer, but add 1.7% agar</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Nematode Growth Medium</td>
			<td style="width:255px;">various</td>
			<td style="width:255px;"></td>
			<td style="width:255px;">see wormbook.org for protocol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">dissecting watch glass</td>
			<td style="width:255px;">Carolina Biological</td>
			<td style="width:255px;">42300</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Parafilm laboratory film</td>
			<td style="width:255px;">Pechiney Plastic Packaging</td>
			<td style="width:255px;">PM-996</td>
			<td style="width:255px;">4 inch wide laboratory film</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">petri dishes</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;">60 mm diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Long glass Pasteur pipettes</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">1ml centrifuge tubes</td>
			<td style="width:255px;">MidSci Avant</td>
			<td style="width:255px;">2926</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Tips</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Serological pipettes</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">500 mL Erlenmyer flask</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Aluminum foil</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">25G 5/8&#8221; needles</td>
			<td style="width:255px;">BD PrecisionGlide&#160;</td>
			<td style="width:255px;">305122</td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">5ml glass centrifuge tube</td>
			<td style="width:255px;">Pyrex&#160;</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Borosilicate glass tubes 1ml</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">glass slides</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">no 1 coverslips 22 x 40 mm</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;">no 1.5 may work, also</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">37 &#176;C Shaker incubator</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Tabletop Centrifuge</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Clinical Centrifuge</td>
			<td style="width:255px;">IEC</td>
			<td style="width:255px;">428</td>
			<td style="width:255px;">with 6 swinging bucket rotor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Mini Centrifuge</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:255px;">20 &#176;C incubator</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:255px;">4 &#176;C refrigerator</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">-20 &#176;C freezer</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="28">
			<td height="28" style="height:28px;width:255px;">Observer Z1 microscope</td>
			<td style="width:255px;">Zeiss</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Plan Apo 63X 1.4 oil-immersion objective lens</td>
			<td style="width:255px;">Zeiss</td>
			<td style="width:255px;"></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:255px;">Ultraview Vox spinning disc confocal system</td>
			<td style="width:255px;">PerkinElmer&#160;</td>
			<td style="width:255px;"></td>
			<td style="width:255px;">Nikon spinning disc confocal system works very well, also, as described here: http://wucci.wustl.edu/Facilities/Light-Microscopy&#160;</td>
		</tr>
	</tbody>
</table>

cell cycle analysis in the c. elegans germline with the thymidine analog edu

Cell cycle analysis in eukaryotes frequently utilizes chromosome morphology, expression and/or localization of gene products required for various phases of the cell cycle, or the incorporation of nucleoside analogs. During S-phase, DNA polymerases incorporate thymidine analogs such as EdU or BrdU into chromosomal DNA, marking the cells for analysis. For C. elegans, the nucleoside analog EdU is fed to the worms during regular culture and is compatible with immunofluorescent techniques. The germline of C. elegans is a powerful model system for the studies of signaling pathways, stem cells, meiosis, and cell cycle because it is transparent, genetically facile, and meiotic prophase and cellular differentiation/gametogenesis occur in a linear assembly-like fashion. These features make EdU a great tool to study dynamic aspects of mitotically cycling cells and germline development. This protocol describes how to successfully prepare EdU bacteria, feed them to wild-type C. elegans hermaphrodites, dissect the hermaphrodite gonad, stain for EdU incorporation into DNA, stain with antibodies to detect various cell cycle and developmental markers, image the gonad and analyze the results. The protocol describes the variations in the method and analysis for the measurement of S-phase index, M-phase index, G2 duration, cell cycle duration, rate of meiotic entry, and rate of meiotic prophase progression. This method can be adapted to study the cell cycle or cell history in other tissues, stages, genetic backgrounds, and physiological conditions.

Since DNA synthesis is required to incorporate EdU, one can conclude that EdU-labeled nuclei underwent S-phase during the EdU-labeling time window. One may interpret the nuclei that label in a 30 min feeding with EdU labeled bacteria as nuclei in S-phase at the time of dissection. Nuclei that label in a longer continuous EdU feeding experiment may have labeled early in the time window and since left S-phase, or may have labeled in the late part of the EdU time window. EdU signal co-locali...

Watch this Scientific Journal Video about Cell Cycle Analysis in the C. elegans Germline with the Thymidine Analog EdU at JoVE.com

Cell Cycle Analysis in the C. elegans Germline with the Thymidine Analog EdU

An imaging-based method is described that can be used to identify S-phase and analyze cell cycle dynamics in the C. elegans hermaphrodite germline using the thymidine analog EdU. This method requires no transgenes and is compatible with immunofluorescent staining.

Cell Cycle Analysis in the C. elegans Germline with the Thymidine Analog EdU

Cell cycle analysis in eukaryotes frequently utilizes chromosome morphology, expression and/or localization of gene products required for various phases ...

This method can help answer key questions about the cell cycle and germ line stem cell population dynamics in C.elegans. The main advantages of this technique are that it requires no transgenes, it is compatible with immunofluorescent staining, and it can be modified to study cells under many different conditions. I was very excited when I first saw this method being used in the Scheda lab.Though this method can provide insight into the C.elegans cell cycle, it can also be applied to broader questions about aging, nutrition, or altered genotypes. Generally labs new to this method may struggle with the initial idiodisprepation or C.elegans hematoxylin staining. Begin by using sterile technique to add 200 microliters of 10 millimolar EdU in 100 milliliters of M9 buffer and the appropriate supplements to four milliliters of freshly grown overnight MG 1693 E.coli culture.Making idiodiscious requires a delicate balance between EdU and thymidine supplementation. As the amount of thymidine must be sufficient for the E coli to grow well, while the amount of EdU must be sufficient for the robust shield against leveling. After no more than 24 hours at 37 degrees Celsius and 200 RPM, use sterile technique to split the culture between two to four sterile 50 milliliter conical tubes for centrifugation.Resuspend the pellatin four milliliters of fresh M9 buffer and use the same pipette to apply about 8 drops of EdU labeled E Coli MG1693 solution to the center of individual room temperature 60 milliliter M9 A guard petri dishes. To feed the EdU labeled bacteria to the nematodes, use fresh PBS to wash the C.Elegans from a nematode growth medium dish into a 1.5 milliliter tube and allow the animals to settle briefly by gravity. Wash the animals one to two times with one milliliter of PBS and use a glass pasteur pipette to transfer the nematodes onto the center of the EdU lawn in a tiny drop of PBS.Wait a few minutes for the liquid to be absorbed and incubate the culture for at least 30 minutes at 20 degrees Celsius according to the experimental protocol. At the end of the incubation, use two milliliters of PBS to flush the worms from the EdU culture plate into a glass dissecting dish. After dissection and fixation of the nematode gonads as previously described, rinse a small one milliliter borosilicate glass tube and a long glass pasteur pipette with PBS supplemented with 0.1%tween 20 and use the pipette to transfer the fixed gonads to the tube in a small amount of PBS tween.Collect the gonads by centrifugation and use a long, drawn out glass pasture pipette to remove as much supernatent as possible without disturbing the gonad pellet. For EdU detection, add 100 microLiters of click EdU cocktail to the gonads and cover the tube with laboratory film for a 30 to 60 minute incubation at room temperature. At the end of the incubation, wash the gonads one time with 100 microLiters of reaction rinse buffer, and four times with one milliliter of PBS tween.After the last wash, add 25 microLiters of anti-fade mounting medium supplemented with DAPI to the sample. While the medium is settling over the gonads, place a large 2.5%agarose pad onto a standard glass microscope slide. Then flatten with a second slide.Next, use a long glass pasteur pipette and keep all of the liquid and gonads in the narrow tip of the pipette to minimize sample loss when transferring the gonads to the pad. Using an eyelash glued to a toothpick, distribute the gonads over the agarose pad and remove any dust particles. Then slowly lower a rectangular glass cover slip onto the gonads, taking care to avoid air bubbles, and removing any excess solution with a lab tissue.Counting cells in three dimensions reliably takes some practice. Using Fiji's cell counter plug-in and a script like marks the cells to remove any duplicates helps make the counts reproducible. After allowing the cover slip to settle overnight, use the cell counter plug-in and Fiji to manually count each nucleus, labeling each individual nucleus according to the presence or absence of phosphohistone three EdU or pregenetor zone cell labeling.EdU signal co-localizes with DAPI signal. In some nuclei, the EdU signal covers all of the chromosomes, while in other nuclei, the EdU signal localizes to one to two bright punkta, likely on the X-chromosome, which replicates late in the S-phase. EdU signal from a successful 30 minute labeling localizes to approximately half of the nuclei in the pregenetor zone.While the technique works consistently in wild type young adult animals, a significant fraction of mated 5 day old hermaphrodites fails to label in a 30 minute EdU pulse. The duration of G2 can be estimated by analyzing the percentage of nuclei in the M-phase that are EdU positive over the time course, allowing calculation of the median and maximum duration of G2.The duration of G2 and G1 can be estimated from the percentage of all of the pregenetor zone nuclei that are EdU positive, allowing calculation of the maximum duration of the combined phases. While attempting this procedure, it's important to remember to use the same batch of EdU dishes to minimize inter-experimental variability.Following this procedure, other methods like staining with additional antibodies can be performed or answer additional questions about the cell cycle, cell fate, or signaling pathways. Don't forget that working with nucleicide analogs and parafermeldahyde can be hazardous, and that precautions, such as wearing nitrol gloves, should always be taken while performing this procedure.

cell-cycle-analysis-c-elegans-germline-with-thymidine-analog

Research

JoVE Journal

Developmental Biology

11.2K Views.  Washington University School of Medicine, St. Louis, Missouri. This method can help answer key questions about the cell cycle and germ line stem cell population dynamics in C.elegans. The main advantages of this technique are that it requires no transgenes, it is compatible with immunofluorescent staining, and it can be modified to study cells under many different conditions. I was very excited when I first saw this method being used in the Scheda lab.Though this method can provide insight into the C.elegans cell cycle, it can also be applied to b...