We are grateful to the members of the Karch lab, to the iGE3 genomics plateform, to the Flow Cytometry core facility of the University of Geneva, and to Dr. Jean-Pierre Aubry-Lachainaye who set the protocol for FACS. We thank Luca Stickley for his help with visualizing the reads on IGV. We thank ourselves for gentle permission to reuse figures, and the editors for prompting us to be creative with writing.
This research was funded by the State of Geneva (CI, RKM, FK), the Swiss National Fund for Research (www.snf.ch) (FK and RKM) and donations from the Claraz Foundation (FK).

1. Drosophila Lines Used and Collection of Males
<ol>
	<li>For this protocol, use males expressing GFP in the SCs and not the main cells. Here, an AbdB-GAL4 driver (described in reference18), recombined with UAS-GFP (on chromosome 2) is used. Other appropriate drivers can also be used. For isolation of SCs under different mutant conditions, cross the mutation into lines containing the SC-specific GFP line.</li>
	<li>Collect two batches of about 25 healthy, virgin males...

<ol>
	<li>Avila, F. W., Sirot, L. K., LaFlamme, B. A., Rubinstein, C. D., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insect+seminal+fluid+proteins:+identification+and+function.">Insect seminal fluid proteins: identification and function.</a> Annual Review of Entomology. 56, 21-40 (2011).</li><li>Carmel, I., Tram, U., Heifetz, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mating+induces+developmental+changes+in+the+insect+female+reproductive+tract.">Mating induces developmental changes in the insect female reproductive tract.</a> Current Opinion in Insect Science. 13, 106-113 (2016).</li><li>League, G. P., Baxter, L. L., Wolfner, M. F., Harrington, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Male+accessory+gland+molecules+inhibit+harmonic+convergence+in+the+mosquito+Aedes+aegypti.">Male accessory gland molecules inhibit harmonic convergence in the mosquito Aedes aegypti.</a> Current Biology. 29 (6), R196-R197 (2019).</li><li>Degner, E. 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=Proteins,+Transcripts,+and+Genetic+Architecture+of+Seminal+Fluid+and+Sperm+in+the+Mosquito+Aedes+aegypti.">Proteins, Transcripts, and Genetic Architecture of Seminal Fluid and Sperm in the Mosquito Aedes aegypti.</a> Molecular &amp; Cellular Proteomics. 18 (Suppl 1), S6-S22 (2019).</li><li>Wedell, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Female+receptivity+in+butterflies+and+moths.">Female receptivity in butterflies and moths.</a> Journal of Experimental Biology. 208 (Pt 18), 3433-3440 (2005).</li><li>Laflamme, B. A., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+and+function+of+proteolysis+regulators+in+seminal+fluid.">Identification and function of proteolysis regulators in seminal fluid.</a> Molecular Reproduction and Development. 80 (2), 80-101 (2013).</li><li>Wilson, C., Leiblich, A., Goberdhan, D. C., Hamdy, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Drosophila+Accessory+Gland+as+a+Model+for+Prostate+Cancer+and+Other+Pathologies.">The Drosophila Accessory Gland as a Model for Prostate Cancer and Other Pathologies.</a> Current Topics in Developmental Biology. 121, 339-375 (2017).</li><li>Kubli, E., Bopp, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sexual+behavior:+how+Sex+Peptide+flips+the+postmating+switch+of+female+flies.">Sexual behavior: how Sex Peptide flips the postmating switch of female flies.</a> Current Biology. 22 (13), R520-R522 (2012).</li><li>Kubli, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sex-peptides:+seminal+peptides+of+the+Drosophila+male.">Sex-peptides: seminal peptides of the Drosophila male.</a> Cellular and Molecular Life Sciences. 60 (8), 1689-1704 (2003).</li><li>Liu, H., Kubli, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sex-peptide+is+the+molecular+basis+of+the+sperm+effect+in+Drosophila+melanogaster.">Sex-peptide is the molecular basis of the sperm effect in Drosophila melanogaster.</a> Proceedings of the National Academy of Sciences of the United States of America. 100 (17), 9929-9933 (2003).</li><li>Ram, K. R., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sustained+post-mating+response+in+Drosophila+melanogaster+requires+multiple+seminal+fluid+proteins.">Sustained post-mating response in Drosophila melanogaster requires multiple seminal fluid proteins.</a> PLoS Genetics. 3 (12), e238 (2007).</li><li>Sitnik, J. L., Gligorov, D., Maeda, R. K., Karch, F., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Female+Post-Mating+Response+Requires+Genes+Expressed+in+the+Secondary+Cells+of+the+Male+Accessory+Gland+in+Drosophila+melanogaster.">The Female Post-Mating Response Requires Genes Expressed in the Secondary Cells of the Male Accessory Gland in Drosophila melanogaster.</a> Genetics. 202 (3), 1029-1041 (2016).</li><li>Avila, F. W., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acp36DE+is+required+for+uterine+conformational+changes+in+mated+Drosophila+females.">Acp36DE is required for uterine conformational changes in mated Drosophila females.</a> Proceedings of the National Academy of Sciences of the United States of America. 106 (37), 15796-15800 (2009).</li><li>Adams, E. M., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seminal+proteins+but+not+sperm+induce+morphological+changes+in+the+Drosophila+melanogaster+female+reproductive+tract+during+sperm+storage.">Seminal proteins but not sperm induce morphological changes in the Drosophila melanogaster female reproductive tract during sperm storage.</a> Journal of Insect Physiology. 53 (4), 319-331 (2007).</li><li>Singh, 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=Long-term+interaction+between+Drosophila+sperm+and+sex+peptide+is+mediated+by+other+seminal+proteins+that+bind+only+transiently+to+sperm.">Long-term interaction between Drosophila sperm and sex peptide is mediated by other seminal proteins that bind only transiently to sperm.</a> Insect Biochemistry and Molecular Biology. 102, 43-51 (2018).</li><li>Avila, F. W., Wolfner, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cleavage+of+the+Drosophila+seminal+protein+Acp36DE+in+mated+females+enhances+its+sperm+storage+activity.">Cleavage of the Drosophila seminal protein Acp36DE in mated females enhances its sperm storage activity.</a> Journal of Insect Physiology. 101, 66-72 (2017).</li><li>Chapman, T., Davies, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functions+and+analysis+of+the+seminal+fluid+proteins+of+male+Drosophila+melanogaster+fruit+flies.">Functions and analysis of the seminal fluid proteins of male Drosophila melanogaster fruit flies.</a> Peptides. 25 (9), 1477-1490 (2004).</li><li>Gligorov, D., Sitnik, J. L., Maeda, R. K., Wolfner, M. F., Karch, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+function+for+the+Hox+gene+Abd-B+in+the+male+accessory+gland+regulates+the+long-term+female+post-mating+response+in+Drosophila.">A novel function for the Hox gene Abd-B in the male accessory gland regulates the long-term female post-mating response in Drosophila.</a> PLoS Genetics. 9 (3), e1003395 (2013).</li><li>Minami, 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=The+homeodomain+protein+defective+proventriculus+is+essential+for+male+accessory+gland+development+to+enhance+fecundity+in+Drosophila.">The homeodomain protein defective proventriculus is essential for male accessory gland development to enhance fecundity in Drosophila.</a> PLoS One. 7 (3), e32302 (2012).</li><li>Maeda, R. K., 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=The+lncRNA+male-specific+abdominal+plays+a+critical+role+in+Drosophila+accessory+gland+development+and+male+fertility.">The lncRNA male-specific abdominal plays a critical role in Drosophila accessory gland development and male fertility.</a> PLoS Genetics. 14 (7), e1007519 (2018).</li><li>Prince, E., 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=Rab-mediated+trafficking+in+the+secondary+cells+of+Drosophila+male+accessory+glands+and+its+role+in+fecundity.">Rab-mediated trafficking in the secondary cells of Drosophila male accessory glands and its role in fecundity.</a> Traffic. 20 (2), 137-151 (2019).</li><li>Robinson, M. D., Oshlack, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+scaling+normalization+method+for+differential+expression+analysis+of+RNA-seq+data.">A scaling normalization method for differential expression analysis of RNA-seq data.</a> Genome Biology. 11 (3), R25 (2010).</li><li>Khan, S. J., Abidi, S. N., Tian, Y., Skinner, A., Smith-Bolton, R. 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+rapid,+gentle+and+scalable+method+for+dissociation+and+fluorescent+sorting+of+imaginal+disc+cells+for+mRNA+sequencing.">A rapid, gentle and scalable method for dissociation and fluorescent sorting of imaginal disc cells for mRNA sequencing.</a> Fly (Austin). 10 (2), 73-80 (2016).</li><li>Corrigan, L., 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=BMP-regulated+exosomes+from+Drosophila+male+reproductive+glands+reprogram+female+behavior.">BMP-regulated exosomes from Drosophila male reproductive glands reprogram female behavior.</a> Journal of Cell Biology. 206 (5), 671-688 (2014).</li><li>Leiblich, 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=Bone+morphogenetic+protein-+and+mating-dependent+secretory+cell+growth+and+migration+in+the+Drosophila+accessory+gland.">Bone morphogenetic protein- and mating-dependent secretory cell growth and migration in the Drosophila accessory gland.</a> Proceedings of the National Academy of Sciences of the United States of America. 109 (47), 19292-19297 (2012).</li><li>Kubo, 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=Nutrient+conditions+sensed+by+the+reproductive+organ+during+development+optimize+male+fecundity+in+Drosophila.">Nutrient conditions sensed by the reproductive organ during development optimize male fecundity in Drosophila.</a> Genes to Cells. 23 (7), 557-567 (2018).</li><li>Immarigeon, C., Karch, F., Maeda, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FACS-based+isolation+and+RNA+extraction+of+Secondary+Cells+from+the+Drosophila+male+Accessory+Gland.">FACS-based isolation and RNA extraction of Secondary Cells from the Drosophila male Accessory Gland.</a> bioRxiv. , 630335 (2019).</li></ol>

Methods for cell dissociation from Drosophila tissue like imaginal discs are already described23. Our attempts to simply use these procedures on accessory glands failed, encouraging us to develop this new protocol. Protease digestion and mechanical trituration were critical steps we troubleshot for the success of the procedure, and we thus placed many notes in sections 2 to 5 to help experimenters to obtain satisfactory results. For dissociation to be successful, peptidases must reach the...

Organs are made up of multiple cell types, each with discrete functions and sometimes expressing vastly different sets of genes. To get a precise understanding of how an organ functions, it is often critical to study each distinct cell type that makes up this organ. One of the primary methods used to explore possible function is transcriptome analysis. This powerful method provides a snapshot of the gene expression in a cell, to reveal active processes and pathways. However, this type of analysis is often difficult for rare cell populations that must be purified from far more-abundant neighboring cells. For example, the Drosophila male accessory gland is an organ made up primarily of two secretory cell types. As the rarer of the two cell types comprises only 4% of the cells of this gland, the use of a cell-type specific transcriptome analysis had not been used to help determine the function of these cells.
Accessory glands (AGs) are organs of the male reproductive tract in insects. They are responsible for the production of most of the proteins of the seminal fluid (seminal fluid proteins (SFPs) and accessory gland proteins (ACPs)). Some of these SFPs are known to induce the physiological and behavioral responses in mated females, commonly called the post-mating response (PMR). Some of the PMRs include: an increased ovulation and egg-laying rate, the storage and release of sperm, a change in female diet, and a decrease in female receptivity to secondary courting males1,2. As insects impact many major societal issues from human health (as vectors for deadly diseases) to agriculture (insects can be pests, yet are critical for pollination and soil quality), understanding insect reproduction is an important area of research. The study of AGs and ACPs has been advanced significantly with the model organism Drosophila melanogaster. These studies have highlighted the role of AGs and some of the individual proteins that they produce in creating the PMR, impacting the work in other species like the disease vector Aedes aegypti3,4, and other insects1,5. Furthermore, as AGs secrete the constituents of the seminal fluid1,6 they are often thought of as the functional analog of the mammalian prostate gland and seminal vesicle. This function similarity combined with molecular similarities between the two tissue-types, have made the AGs a model for the prostate gland in flies7.
Within the Drosophila male, there are two lobes of accessory glands. Each lobe can be seen as a sac-like structure made up of a monolayer of secretory cells surrounding a central lumen, and wrapped by smooth muscles. As mentioned above, there are two morphologically, developmentally and functionally distinct secretory cell types making up this gland: the polygonal-shaped main cells (making up ~96% of the cells), and the larger, round secondary cells (SC) (making up the remaining 4% of cells, or about 40 cells per lobe). It has been shown that both cell types produce distinct sets of ACPs to induce and maintain the PMR. Most of the data obtained to date highlight the role of a single protein in triggering most of the characteristic behaviors of the PMR. This protein, the sex peptide, is a small, 36 amino acid peptide that is secreted by the main cells8,9,10. Although the sex peptide seems to play a major role in the PMR, other ACPs, produced by both the main and secondary cells, have also been shown to affect various aspects of the PMR11,12,13,14,15,16,17. For example, based on our current knowledge, the SCs, via the proteins they produce, seem to be required for the perpetuation of the SP signaling after the first day18.
Given the rarity of the SCs (only 80 cells per male), all our knowledge about these cells and the proteins they produce comes from genetics and candidate approaches. Thus far, only a relatively small list of genes has been shown to be SC-specific. This list includes the homeodomain protein Defective proventriculus (Dve)19, the lncRNA MSA20, Rab6, 7, 11 and 1921, CG1656 and CG1757511,15,21 and the homeobox transcription factor Abdominal-B (Abd-B)18. Previously, we have shown that a mutant deficient for both the expression of Abd-B and the lncRNA MSA in secondary cells (iab-6cocuD1 mutant) shortens the length of the PMR from ~10 days to only one day12,18,20. This phenotype seems to be caused by the improper storage of SP in the female reproductive tract12,18,20. At the cellular level, the secondary cells of this mutant show abnormal morphology, losing their characteristic vacuole-like structures18,20,21. Using this mutant line, we previously attempted to identify genes involved in SC function by comparing the transcriptional profiles of whole AGs from either wild type or mutant accessory glands12. Also, other labs showed that SC number, morphology and vacuolar content depend on male diet, mating status and age21,25,26.
Although positive progress was made using these approaches, a full SC transcriptome was far from achieved. The rareness of these cells in this organ made it difficult to progress further even from wild type cells. For testing gene expression, changes in these cells after particular environmental stimuli would be even harder. Thus, a method for isolating and purifying SC RNA that was fast and simple enough to perform under different genetic backgrounds and environmental conditions was needed.
Both the Abd-B and MSA genes require a specific 1.1 kb enhancer from the Drosophila Bithorax Complex (called the D1 enhancer) for their expression in SCs18,20. This enhancer has previously been used to create a GAL4 driver that, when associated with a UAS-GFP, is able to drive strong GFP expression specifically in SCs. Thus, we used this line as the basis for a FACS protocol to isolate these cells from both wild type and iab-6cocuD1 AGs). As iab-6cocuD1 mutant SCs display a different cellular morphology, we show that this protocol can be used to isolate cells for the determination of their transcriptome from this rare cell type under vastly different conditions.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>24-wells Tissue Culture plate</td>
			<td>VWR</td>
			<td>734-2325</td>
			<td></td>
		</tr>
		<tr>
			<td>Binocular microscope for dissection</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Binocular with light source for GFP</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bunsen</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Draq7 0.3 mM</td>
			<td>BioStatus</td>
			<td>DR71000</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic microtubes 1.5 mL</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FACS</td>
			<td>Beckman Coulter</td>
			<td>MoFlo Astrios</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine dissection forceps</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Foetal bovine serum</td>
			<td>Gibco</td>
			<td>10270-106</td>
			<td>heat inactivated prior to use</td>
		</tr>
		<tr>
			<td>Glass dishes for dissection</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ice bucket</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ImProm-II Reverse Transcription System</td>
			<td>Promega</td>
			<td>A3800</td>
			<td></td>
		</tr>
		<tr>
			<td>MasterPure RNA Purification Kit</td>
			<td>Epicentre</td>
			<td>MCR85102</td>
			<td></td>
		</tr>
		<tr>
			<td>Nextera XT kit</td>
			<td>illumina</td>
			<td></td>
			<td><a href="https://emea.illumina.com/products/by-type/sequencing-kits/library-prep-kits/nextera-xt-dna.html">https://emea.illumina.com/products/by-type/sequencing-kits/library-prep-kits/nextera-xt-dna.html</a></td>
		</tr>
		<tr>
			<td>P1000</td>
			<td>Gilson</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>P20</td>
			<td>Gilson</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>P200</td>
			<td>Gilson</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Papain</td>
			<td></td>
			<td></td>
			<td>50U/mL stock</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td></td>
			<td></td>
			<td>home made</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Gibco</td>
			<td>15070-063</td>
			<td></td>
		</tr>
		<tr>
			<td>PolydT primers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Random hexamer primers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>RNA 6000 Pico kit</td>
			<td>Agilent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Schneider&#8217;s Drosophila medium</td>
			<td>Gibco</td>
			<td>21720-001</td>
			<td></td>
		</tr>
		<tr>
			<td>SMARTer cDNA synthesis kit</td>
			<td>Takara</td>
			<td></td>
			<td><a href="https://www.takarabio.com/products/cdna-synthesis/cdna-synthesis-kits/smarter-cdna-synthesis-kits">https://www.takarabio.com/products/cdna-synthesis/cdna-synthesis-kits/smarter-cdna-synthesis-kits</a></td>
		</tr>
		<tr>
			<td>SYBR select Master mix for CFX</td>
			<td>applied biosystems</td>
			<td>4472942</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermo Shaker</td>
			<td>Hangzhou Allsheng intruments</td>
			<td>MS-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Tipone 1250 &#956;l graduated tip</td>
			<td>Starlab</td>
			<td>S1161-1820</td>
			<td></td>
		</tr>
		<tr>
			<td>Tipone 200 &#956;l bevelled tip</td>
			<td>Starlab</td>
			<td>S1161-1800</td>
			<td></td>
		</tr>
		<tr>
			<td>TrypLE Express Enzyme</td>
			<td>Gibco</td>
			<td>12604013</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

a facs-based protocol to isolate rna from the secondary cells of drosophila male accessory glands

To understand the function of an organ, it is often useful to understand the role of its constituent cell populations. Unfortunately, the rarity of individual cell populations often makes it difficult to obtain enough material for molecular studies. For example, the accessory gland of the Drosophila male reproductive system contains two distinct secretory cell types. The main cells make up 96% of the secretory cells of the gland, while the secondary cells (SC) make up the remaining 4% of cells (about 80 cells per male). Although both cell types produce important components of the seminal fluid, only a few genes are known to be specific to the SCs. The rarity of SCs has, thus far, hindered transcriptomic analysis study of this important cell type. Here, a method is presented that allows for the purification of SCs for RNA extraction and sequencing. The protocol consists in first dissecting glands from flies expressing a SC-specific GFP reporter and then subjecting these glands to protease digestion and mechanical dissociation to obtain individual cells. Following these steps, individual, living, GFP-marked cells are sorted using a fluorescent activated cell sorter (FACS) for RNA purification. This procedure yields SC-specific RNAs from ~40 males per condition for downstream RT-qPCR and/or RNA sequencing in the course of one day. The rapidity and simplicity of the procedure allows for the transcriptomes of many different flies, from different genotypes or environmental conditions, to be determined in a short period of time.

The protocol presented here enables one experimenter to isolate secondary cells from Drosophila male accessory glands and to extract their RNA in the course of one single day (Figure 1).
We use the Abd-B-GAL4 construct18 to label secondary cells (SC) but not main cells (MC) with GFP (Figure 2A). One objective of...

Watch this Scientific Journal Video about A FACS-based Protocol to Isolate RNA from the Secondary Cells of Drosophila Male Accessory Glands at JoVE.com

A FACS-based Protocol to Isolate RNA from the Secondary Cells of Drosophila Male Accessory Glands

Here, we present a protocol to dissociate and sort a specific cell population from the Drosophila male accessory glands (secondary cells) for RNA sequencing and RT-qPCR. Cell isolation is accomplished through FACS purification of GFP-expressing secondary cells after a multistep-dissociation process requiring dissection, proteases digestion and mechanical dispersion.

A FACS-based Protocol to Isolate RNA from the Secondary Cells of Drosophila Male Accessory Glands

To understand the function of an organ, it is often useful to understand the role of its constituent cell populations. Unfortunately, the rarity of ...

This method permits a transcriptomic analysis of a rare cell population from Drosophila male accessory gland, called the secondary cells, and it uncovers genes that make them critical for reproductive success. In the course of one day, this technique allows the sorting of secondary cells from different genotype and the extraction of the total RNA for subsequent qPCR or RNA sequencing. Sometimes projects are limited by the rarity of starting material.This method can provide the basis for other groups facing the challenge of working with a rare cell population. Because the procedure needs to accumulate 40 glands, it's important to practice the dissections. Preparing the homemade pipette tips is also important, and so you should visualize it on the video how to make it and prepare in advance.Before beginning the procedure, cut and flame round, wide, 200-microliter tips for handling the glands, and pass the tip opening of multiple 1, 000-microliter tips near a flame for less than one second to narrow the openings. Then, sort the modified tips from narrower to wider based on their speed of aspiration. For accessary gland dissection, place 20 to 25 male Drosophila in a glass dish on ice, and use forceps and a dissection microscope to remove the reproductive tract of one male fly.Clear the accessory gland pair from all of the other tissues, including the testes and ejaculatory bulb, and transfer the accessory glands to a glass plate containing serum-supplemented medium at room temperature. When 20 pairs of accessory glands have been collected, wash the glands in a dish of PBS for one to two minutes at room temperature. At the end of the wash, transfer the glands to freshly prepared dissociation solution, and use sharp forceps under a dissecting microscope to firmly pinch the middle of a glandular lobe.Using a second pair of forceps, cut the tissue with the sharp tip to separate the proximal region of the accessory gland and the ejaculatory duct from the portion of the gland containing secondary cells. Cut the glands so that the peptidases can reach the cells that are otherwise protected by the outer muscle layer and by the viscous seminal fluid in the lumen of the gland. Then, use a pre-wet, flame-rounded, wide, 200-microliter pipette tip to transfer the glands to a 1.5-milliliter tube.For tissue digestion, place the tube in a 37-degree Celsius shaker for 60 minutes at 1, 000 rotations per minute. At the end of the incubation, stop the digestion with one milliliter of serum-supplemented medium, and use a pre-wet, flame-rounded, wide, 1, 000-microliter pipette tip to transfer the samples to a 24-well plate. Check the cells for their GFP expression under a fluorescent microscope.Most of the gland tips should look intact, and a few secondary cells should be detached. Use a rounded, narrow, 1, 000-microliter pipette tip to gently triturate the cells three to five times to disrupt the accessory gland tissue. Then, use a very narrow, rounded, 1, 000-microliter pipette tip one to two times to individualize the cells.Allow the cells to settle for 15 minutes. Confirm that the cells appear healthy under the microscope, and remove the excess medium. Then, transfer the cells into a new 1.5-milliliter tube, and rinse the wells with fresh medium to recover any remaining cells.The Abd-B-GAL4 construct can be used in these experiments to label secondary but not main cells with GFP. In this study, both cell types were sorted from wild type and iab-6cocuD1 mutant accessory glands. This D1 mutant lacks the expression of Abd-B and MSA transcripts, which affect secondary cells development, morphology, and function.After cell dissociation, FACS is used to select living cells based on DRAQ7, and GFP fluorescence level is used to isolate secondary cells and main cells. RNA is extracted from each cell population and adjusted to two nanograms per sample for subsequent RT-qPCR and sequencing. Quantification of the expression of specific genes by real-time quantitative PCR on wild type main and secondary cell extracts reveals that the secondary cell genes Rab19 and MSA are detected from only secondary cell extracts, while the main cell gene sex peptide is detected only from main cell samples.Principal component analysis on RNA-sequencing data of three wild type and three mutant replicates reveals that the wild type replicates both cluster close together to each other and far from the mutant samples. Visualizing reads aligned to particular genes shows that housekeeping genes such as actin 5C, and the secondary cell-specific genes Rab19 and Dve are expressed in both genotypes. For MSA, however, the strong expression of the gene observed in wild type flies is lost in the mutant strains.Obtaining enough living dissociated secondary cells is important for a successful procedure. Thus, verify the dissection and dissociation protocol in small-scale experiment. This method allows the sorting of both cell type of accessory gland from a small number of flies, enabling the study of how those cell react transcriptionally to multiple genetic or environmental conditions.Male reproductive success is known to be affected by many things, including genotype, age, and mating status. The ease of this method should allow us to investigate how these factors affect accessory gland transcription.

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JoVE Journal

Genetics

6.8K vistas.  University of Geneva. Este método permite un análisis transcriptómico de una población celular rara de la glándula accesoria masculina Drosophila, llamada células secundarias, y descubre genes que las hacen críticas para el éxito reproductivo. En el transcurso de un día, esta técnica permite la clasificación de células secundarias de diferentes genotipos y la extracción del ARN total para la secuenciación posterior de qPCR o ARN. A veces los proyectos están limitados por la rareza del material inici...

Video: A FACS-based Protocol to Isolate RNA from the Secondary Cells of Drosophila Male Accessory Glands

Here, we present a protocol to dissociate and sort a specific cell population from the Drosophila male accessory glands (secondary cells) for RNA sequencing and RT-qPCR. Cell isolation is accomplished through FACS purification of GFP-expressing secondary cells after a multistep-dissociation process requiring dissection, proteases digestion and mechanical...

drosophila male accessory gland dissection: a method to isolate secondary cells

This video describes the dissection of the accessory glands from male flies and shows an example in which the isolated gland will be dissociated into a single cell...

Drosophila Male Accessory Gland Dissection: A Method to Isolate Secondary Cells

gastric fundic glands isolation: a method to isolate fundic glands from human stomach tissue

This video describes a method to isolate gastric epithelial cells from the human fundic tissue. The isolated epithelial cells can be used as an in vitro model to study their regulatory roles in gastric physiology and...

Gastric Fundic Glands Isolation: A Method to Isolate Fundic Glands from Human Stomach Tissue

Next, use large forceps to hold the muscle layer of the tissue firmly. Then, use large curved hemostatic forceps and scrape the epithelium with force. Store the scraped epithelium in a sterile polystyrene Petri dish. To optimize the tissue digestion, mince the epithelial tissue into fragments. Then, wash the tissue with calcium/magnesium-free DPBS supplemented with...

isolating intestinal stem cells from adult drosophila midguts by facs to study stem cell behavior during aging

Isolating Intestinal Stem Cells from Adult Drosophila Midguts by FACS to Study Stem Cell Behavior During Aging

Understanding the endogenous molecular changes in adult stem cells during aging requires isolating the cells of interest. The method described here presents a simple and robust approach to enrich for and isolate Drosophila intestinal stem cells and the enteroblast progenitor cells by FACS at any time point during aging.

Isolating Intestinal Stem Cells from Adult Drosophila Midguts by FACS to Study Stem Cell Behavior During Aging

a technique to isolate nuclei from non-neuronal cells in the hippocampal dentate gyrus

The video demonstrates a method for isolating intact nuclei from glial and stem cells in the mouse hippocampal dentate gyrus (DG). The DG tissue is mechanically dissociated in a cold homogenization buffer to release the nuclei. Tissue debris and other released organelles are discarded, and the nuclei are stained with a DNA stain and a fluorophore-conjugated antibody specific for the neuronal nuclear antigen (NeuN). Fluorescence-activated nuclei sorting is then employed to isolate the...

A Technique to Isolate Nuclei from Non-neuronal Cells in the Hippocampal Dentate Gyrus

effect of male accessory gland products on egg laying in gastropod molluscs

Effect of Male Accessory Gland Products on Egg Laying in Gastropod Molluscs

This video protocol demonstrates a method to study effects of seminal fluid in gastropods, using the hermaphroditic freshwater snail Lymnaea...

an in vivo crosslinking approach to isolate protein complexes from drosophila embryos

An in vivo Crosslinking Approach to Isolate Protein Complexes From Drosophila Embryos

Multi-component protein complexes play crucial roles during cellular function and development. Here we describe a method used to isolate native protein complexes from Drosophila embryos after in vivo crosslinking followed by purification of the crosslinked complexes for subsequent structure-function analysis.<br...

An in vivo Crosslinking Approach to Isolate Protein Complexes From Drosophila Embryos

a non-invasive way to isolate and phenotype cells from the conjunctiva

A Non-invasive Way to Isolate and Phenotype Cells from the Conjunctiva

The exposed normal ocular surface consists of cornea and conjunctiva. Epithelial cells, goblet cells and immune cells are present in the conjunctiva. Here, a non-invasive, technique of impression cytology is described using an impression cytology device and flow cytometry to analyze immune cells in the...

isolation of myoepithelial cells from adult murine lacrimal and submandibular glands

Isolation of Myoepithelial Cells from Adult Murine Lacrimal and Submandibular Glands

The lacrimal gland (LG) has two cell types expressing &#945;-smooth muscle actin (&#945;SMA): myoepithelial cells (MECs) and pericytes. MECs are of ectodermal origin, found in many glandular tissues, while pericytes are vascular smooth muscle cells of endodermal origin. This protocol isolates MECs and pericytes from murine...

a technique to isolate primary mast cells from a murine peritoneal cavity

This video demonstrates a peritoneal lavage method for isolating mature connective tissue-type mast cells from the peritoneal cavity of adult mice. Upon isolating a mixture of primary immune cells from the peritoneal cavity, selective proliferation of mast cells is performed under appropriate culture...

A Technique to Isolate Primary Mast Cells from a Murine Peritoneal Cavity

a technique to isolate satellite cells from rat head muscle tissue

This video demonstrates the isolation of satellite cells from rat head branchiomeric muscle tissues through tissue dissection, enzymatic digestion, and subsequent mechanical and centrifugal purification. The cells are then seeded on extracellular matrix-coated wells for differentiation into myoblasts, and eventually into myotubes and mature muscle...

A Technique to Isolate Satellite Cells From Rat Head Muscle Tissue

measurement of poly a tail length from drosophila larva brain and cell line

Author Spotlight: Exploring the Frontier of mRNA Research with Poly A Tail Analysis Techniques

The protocol describes an efficient and reliable method for quantifying the poly(A) length of the gene of interest from the Drosophila nervous system, which can be easily adapted to tissues or cell types from other species.

 Quantifying the Poly(A) Length of Genes from the &lt;em&gt;Drosophila&lt;/em&gt; Nervous System

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a protocol for immunohistochemistry and rna in-situ distribution within early drosophila embryo

A Protocol for Immunohistochemistry and RNA In-situ Distribution within Early Drosophila Embryo

Here, we describe a protocol for detection and localization of Drosophila embryo protein and RNA from collection to pre-embedding and embedding, immunostaining, and mRNA in situ...

A Protocol for Immunohistochemistry and RNA In-situ Distribution within Early Drosophila Embryo

isolating mouse brain vessels: a protocol to isolate intact vessels from murine brain sample

This video demonstrates the isolation of intact vessels from a mouse&#39;s brain that constitute the blood-brain barrier (BBB) along with neurons and glial cells. The isolated vessels can be used as an in vitro model to study their role in maintaining brain...

Isolating Mouse Brain Vessels: A Protocol to Isolate Intact Vessels from Murine Brain Sample

an efficient protocol for cut&amp;run analysis of facs-isolated mouse satellite cells

Author Spotlight: Cistrome Analysis in Mouse Muscle Stem Cells 

Presented here is an efficient protocol for the fluorescence-activated cell sorting (FACS) isolation of mouse limb muscle satellite cells adapted to the study of transcription regulation in muscle fibers by cleavage under targets and release using nuclease...

An Efficient Protocol for CUT&amp;RUN Analysis of FACS-Isolated Mouse Satellite Cells

Next, inject 7 milliliters of ice-cold RPMI medium in the peritoneal cavity by inserting a 27-gauge needle carefully in the peritoneum. Do not perforate any organs and use a spot in the region of the epididymal fat to reduce the risk of an organ...

Add 3 milliliters of HB to the 15-milliliter tube, and incubate for 5 minutes on ice. Mix this nuclei suspension twice by inverting the tube gently. Using 0.5 milliliters of HB, pre-wet the 70-micrometer strainer cap placed over a 50-milliliter test tube. Then, strain the nuclei suspension before washing the cell strainer with 0.5 milliliters of...

side population assay: a method to isolate side population of tumor cells from zebrafish

The following protocol describes a method for isolating the side population of T-cell Acute Lymphoblastic Leukemia (T-ALL) tumor cells, consisting of stem cells, from an adult Zebrafish. The side population lacks prominent cell markers and hence we use Hoechst 33342 dye efflux assay to isolate...

Side Population Assay: A Method to Isolate Side Population of Tumor Cells from Zebrafish

When the fiber bundles exhibit a loosened appearance, add 2.5 milliliters of DMEM, supplemented with horse serum and antibiotics to each well, and transfer the digested tissues to individual 15-milliliter conical tubes. Spin down the tissue slurries, and decant the supernatants. Then, add 5 milliliters of medium to each tube, and homogenize the tissue with a 10-milliliter plastic...

Mapping RNA-RNA Interactions Globally Using Biotinylated Psoralen

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA interactions such as microRNA-mRNA interactions have been shown to regulate gene expression, the full extent to which RNA interactions occur in the cell is still unknown. Previous methods to study RNA interactions have primarily focused on subsets of RNAs that are interacting with a particular protein or RNA species. Here, we detail a method named Sequencing of Psoralen crosslinked, Ligated, and Selected Hybrids (SPLASH) that allows genome-wide capture of RNA interactions in vivo in an unbiased manner. SPLASH utilizes in vivo crosslinking, proximity ligation, and high throughput sequencing to identify intramolecular and intermolecular RNA base-pairing partners globally. SPLASH can be applied to different organisms including bacteria, yeast and human cells, as well as diverse cellular conditions to facilitate the understanding of the dynamics of RNA organization under diverse cellular contexts. The entire experimental SPLASH protocol takes about 5 days to complete and the computational workflow takes about 7 days to complete.

Here, we detail the method of Sequencing of Psoralen crosslinked, Ligated, and Selected Hybrids (SPLASH), which enables genome-wide mapping of intramolecular and intermolecular RNA-RNA interactions in vivo. SPLASH can be applied to study RNA interactomes of organisms including yeast, bacteria and humans.

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA ...

A Universal Protocol for Large-scale gRNA Library Production from any DNA Source

The popularity of the CRISPR/Cas9 system for both genome and epigenome engineering stems from its simplicity and adaptability. An effector (the Cas9 nuclease or a nuclease-dead dCas9 fusion protein) is targeted to a specific site in the genome by a small synthetic RNA known as the guide RNA, or gRNA. The bipartite nature of the CRISPR system enables its use in screening approaches since plasmid libraries containing expression cassettes of thousands of individual gRNAs can be used to interrogate many different sites in a single experiment. 
To date, gRNA sequences for the construction of libraries have been almost exclusively generated by oligonucleotide synthesis, which limits the achievable complexity of sequences in the library and is relatively cost-intensive. Here, a detailed protocol for CORALINA (comprehensive gRNA library generation through controlled nuclease activity), a simple and cost-effective method for the generation of highly complex gRNA libraries based on enzymatic digestion of input DNA, is described. Since CORALINA libraries can be generated from any source of DNA, plenty of options for customization exist, enabling a large variety of CRISPR-based screens.

Methods for generating large-scale gRNA libraries should be simple, efficient and cost-effective. We describe a protocol for the production of gRNA libraries based on enzymatic digestion of target DNA. This method, CORALINA (comprehensive gRNA library generation through controlled nuclease activity) presents an alternative to costly custom oligonucleotide synthesis.

The popularity of the CRISPR/Cas9 system for both genome and epigenome engineering stems from its simplicity and adaptability. An effector (the Cas9 ...

A Protocol for the Production of Integrase-deficient Lentiviral Vectors for CRISPR/Cas9-mediated Gene Knockout in Dividing Cells

Lentiviral vectors are an ideal choice for delivering gene-editing components to cells due to their capacity for stably transducing a broad range of cells and mediating high levels of gene expression. However, their ability to integrate into the host cell genome enhances the risk of insertional mutagenicity and thus raises safety concerns and limits their usage in clinical settings. Further, the persistent expression of gene-editing components delivered by these integration-competent lentiviral vectors (ICLVs) increases the probability of promiscuous gene targeting. As an alternative, a new generation of integrase-deficient lentiviral vectors (IDLVs) has been developed that addresses many of these concerns. Here the production protocol of a new and improved IDLV platform for CRISPR-mediated gene editing and list the steps involved in the purification and concentration of such vectors is described and their transduction and gene-editing efficiency using HEK-293T cells was demonstrated. This protocol is easily scalable and can be used to generate high titer IDLVs that are capable of transducing cells in vitro and in vivo. Moreover, this protocol can be easily adapted for the production of ICLVs.

We describe the production strategy of integrase-deficient lentiviral vectors (IDLVs) as vehicles for delivering CRISPR/Cas9 to cells. With an ability to mediate quick and robust gene editing in cells, IDLVs present a safer and equally effective vector platform for gene delivery compared to integrase-competent vectors.

Lentiviral vectors are an ideal choice for delivering gene-editing components to cells due to their capacity for stably transducing a broad range of cells ...

RNA Pull-down Procedure to Identify RNA Targets of a Long Non-coding RNA

Long non-coding RNA (lncRNA), which are sequences of more than 200 nucleotides without a defined reading frame, belong to the regulatory non-coding RNA&#39;s family. Although their biological functions remain largely unknown, the number of these lncRNAs has steadily increased and it is now estimated that humans may have more than 10,000 such transcripts. Some of these are known to be involved in important regulatory pathways of gene expression which take place at the transcriptional level, but also at different steps of RNA co- and post-transcriptional maturation. In the latter cases, RNAs that are targeted by the lncRNA have to be identified. That&#39;s the reason why it is useful to develop a method enabling the identification of RNAs associated directly or indirectly with a lncRNA of interest.
This protocol, which was inspired by previously published protocols allowing the isolation of a lncRNA together with its associated chromatin sequences, was adapted to permit the isolation of associated RNAs. We determined that two steps are critical for the efficiency of this protocol. The first is the design of specific anti-sense DNA oligonucleotide probes able to hybridize to the lncRNA of interest. To this end, the lncRNA secondary structure was predicted by bioinformatics and anti-sense oligonucleotide probes were designed with a strong affinity for regions that display a low probability of internal base pairing. The second crucial step of the procedure relies on the fixative conditions of the tissue or cultured cells that have to preserve the network between all molecular partners. Coupled with high throughput RNA sequencing, this RNA pull-down protocol can provide the whole RNA interactome of a lncRNA of interest.

This RNA pull-down method allows identifying the RNA targets of a long non-coding RNA (lncRNA). Based on the hybridization of home-made, designed anti-sense DNA oligonucleotide probes specific to this lncRNA in an appropriately fixed tissue or cell line, it efficiently allows the capture of all RNA targets of the lncRNA.

Long non-coding RNA (lncRNA), which are sequences of more than 200 nucleotides without a defined reading frame, belong to the regulatory non-coding ...

The TreadWheel: Interval Training Protocol for Gently Induced Exercise in Drosophila melanogaster

The incidence of complex metabolic diseases has increased as a result of a widespread transition towards lifestyles of increased caloric intake and lowered activity levels. These multifactorial diseases arise from a combination of genetic, environmental, and behavioral factors. One such complex disease is Metabolic Syndrome (MetS), which is a cluster of metabolic disorders, including hypertension, hyperglycemia, and abdominal obesity. Exercise and dietary intervention are the primary treatments recommended by doctors to mitigate obesity and its subsequent metabolic diseases. Exercise intervention, in particular aerobic interval training, stimulates favorable changes in the common risk factors for Type 2 Diabetes Mellitus (T2DM), Cardiovascular Disease (CVD), and other conditions. With the influx of evidence describing the therapeutic effect exercise has on metabolic health, establishing a system that models exercise in a controlled setting provides a valuable tool for assessing the effects of exercise in an experimental context. Drosophila melanogaster is a great tool for investigating the physiological and molecular changes that result from exercise intervention. The flies have short lifespans and similar mechanisms of metabolizing nutrients when compared to humans. To induce exercise in Drosophila, we developed a machine called the TreadWheel, which utilizes the fly&#39;s innate, negative geotaxis tendency to gently induce climbing. This enables researchers to perform experiments on large cohorts of genetically diverse flies to better understand the genotype-by-environment interactions underlying the effects of exercise on metabolic health.

The TreadWheel: Interval Training Protocol for Gently Induced Exercise in Drosophila melanogaster

The TreadWheel uses rotational motion to gently induce exercise in adult Drosophila melanogaster by exploiting flies&#39; innate, negative geotaxis. It allows for analysis of the interactions between exercise and factors, such as genotype, sex, and diet, and their effect on physiological and molecular assays to assess metabolic health.

The incidence of complex metabolic diseases has increased as a result of a widespread transition towards lifestyles of increased caloric intake and ...

Purification of Low-abundant Cells in the Drosophila Visual System

Recent improvements in the sensitivity of next generation sequencing have facilitated the application of transcriptomic and genomic analyses to small numbers of cells. Utilizing this technology to study development in the Drosophila visual system, which boasts a wealth of cell type-specific genetic tools, provides a powerful approach for addressing the molecular basis of development with precise cellular resolution. For such an approach to be feasible, it is crucial to have the capacity to reliably and efficiently purify cells present at low abundance within the brain. Here, we present a method that allows efficient purification of single cell clones in genetic mosaic experiments. With this protocol, we consistently achieve a high cellular yield after purification using fluorescence activated cell sorting (FACS) (~25% of all labeled cells), and successfully performed transcriptomics analyses on single cell clones generated through mosaic analysis with a repressible cell marker (MARCM). This protocol is ideal for applying transcriptomic and genomic analyses to specific cell types in the visual system, across different stages of development and in the context of different genetic manipulations.

Here, we present a cell dissociation protocol for efficiently isolating cells present at low abundance within the Drosophila visual system through fluorescence activated cell sorting (FACS).

Recent improvements in the sensitivity of next generation sequencing have facilitated the application of transcriptomic and genomic analyses to small ...

Generation of Cancer Cell Clones to Visualize Telomeric Repeat-containing RNA TERRA Expressed from a Single Telomere in Living Cells

Telomeres are transcribed, giving rise to telomeric repeat-containing long noncoding RNAs (TERRA), which have been proposed to play important roles in telomere biology, including heterochromatin formation and telomere length homeostasis. Recent findings revealed that TERRA molecules also interact with internal chromosomal regions to regulate gene expression in mouse embryonic stem (ES) cells. In line with this evidence, RNA fluorescence in situ hybridization (RNA-FISH) analyses have shown that only a subset of TERRA transcripts localize at chromosome ends. A better understanding of the dynamics of TERRA molecules will help define their function and mechanisms of action. Here, we describe a method to label and visualize single-telomere TERRA transcripts in cancer cells using the MS2-GFP system. To this aim, we present a protocol to generate stable clones, using the AGS human stomach cancer cell line, containing MS2 sequences integrated at a single subtelomere. Transcription of TERRA from the MS2-tagged telomere results in the expression of MS2-tagged TERRA molecules that are visualized by live-cell fluorescence microscopy upon co-expression of a MS2 RNA-binding protein fused to GFP (MS2-GFP). This approach enables researchers to study the dynamics of single-telomere TERRA molecules in cancer cells, and it can be applied to other cell lines.

Here, we present a protocol to generate cancer cell clones containing a MS2 sequence tag at a single subtelomere. This approach, relying on the MS2-GFP system, enables visualization of the endogenous transcripts of telomeric repeat-containing RNA (TERRA) expressed from a single telomere in living cells.

Telomeres are transcribed, giving rise to telomeric repeat-containing long noncoding RNAs (TERRA), which have been proposed to play important roles in ...

Identification of Footprints of RNA:Protein Complexes via RNA Immunoprecipitation in Tandem Followed by Sequencing (RIPiT-Seq)

RNA immunoprecipitation in tandem (RIPiT) is a method for enriching RNA footprints of a pair of proteins within an RNA:protein (RNP) complex. RIPiT employs two purification steps. First, immunoprecipitation of a tagged RNP subunit is followed by mild RNase digestion and subsequent non-denaturing affinity elution. A second immunoprecipitation of another RNP subunit allows for enrichment of a defined complex. Following a denaturing elution of RNAs and proteins, the RNA footprints are converted into high-throughput DNA sequencing libraries. Unlike the more popular ultraviolet (UV) crosslinking followed by immunoprecipitation (CLIP) approach to enrich RBP binding sites, RIPiT is UV-crosslinking independent. Hence RIPiT can be applied to numerous proteins present in the RNA interactome and beyond that are essential to RNA regulation but do not directly contact the RNA or UV-crosslink poorly to RNA. The two purification steps in RIPiT provide an additional advantage of identifying binding sites where a protein of interest acts in partnership with another cofactor. The double purification strategy also serves to enhance signal by limiting background. Here, we provide a step-wise procedure to perform RIPiT and to generate high-throughput sequencing libraries from isolated RNA footprints. We also outline RIPiT&#39;s advantages and applications and discuss some of its limitations.

Identification of Footprints of RNA:Protein Complexes via RNA Immunoprecipitation in Tandem Followed by Sequencing RIPiT-Seq

Here, we present a protocol to enrich endogenous RNA binding sites or &#34;footprints&#34;&#160;of RNA:protein (RNP) complexes from mammalian cells. This approach involves two immunoprecipitations of RNP subunits and is therefore dubbed RNA immunoprecipitation in tandem (RIPiT).

RNA immunoprecipitation in tandem (RIPiT) is a method for enriching RNA footprints of a pair of proteins within an RNA:protein (RNP) complex. RIPiT ...

Use of Drosophila S2 Cells for Live Imaging of Cell Division

Drosophila S2 cells are an important tool in studying mitosis in tissue culture, providing molecular insights into this fundamental cellular process in a rapid and high-throughput manner. S2 cells have proven amenable to both fixed- and live-cell imaging applications. Notably, live-cell imaging can yield valuable information about how loss or knockdown of a gene can affect the kinetics and dynamics of key events during cell division, including mitotic spindle assembly, chromosome congression, and segregation, as well as overall cell cycle timing. Here we utilize S2 cells stably transfected with fluorescently tagged mCherry:&#945;-tubulin to mark the mitotic spindle and GFP:CENP-A (referred to as &#8216;CID&#8217; gene in Drosophila) to mark the centromere to analyze the effects of key mitotic genes on the timing of cell divisions, from prophase (specifically at Nuclear Envelope Breakdown; NEBD) to the onset of anaphase. This imaging protocol also allows for the visualization of the spindle microtubule and chromosome dynamics throughout mitosis. Herein, we aim to provide a simple yet comprehensive protocol that will allow readers to easily adapt S2 cells for live imaging experiments. Results obtained from such experiments should expand our understanding of genes involved in the cell division by defining their role in several simultaneous and dynamic events. Observations made in this cell culture system can be validated and further investigated in vivo using the impressive toolkit of genetic approaches in flies.

Use of Drosophila S2 Cells for Live Imaging of Cell Division

Cell divisions can be visualized in real time using fluorescently tagged proteins and time-lapse microscopy. Using the protocol presented here, users can analyze cell division timing dynamics, mitotic spindle assembly, and chromosome congression and segregation. Defects in these events following RNA interference (RNAi)-mediated gene knockdown can be assessed and quantified.

Drosophila S2 cells are an important tool in studying mitosis in tissue culture, providing molecular insights into this fundamental cellular process in a ...

Characterization of In Vitro Differentiation of Human Primary Keratinocytes by RNA-Seq Analysis

Human primary keratinocytes are often used as in vitro models for studies on epidermal differentiation and related diseases. Methods have been reported for in vitro differentiation of keratinocytes cultured in two-dimensional (2D) submerged manners using various induction conditions. Described here is a procedure for 2D in vitro keratinocyte differentiation method by contact inhibition and subsequent molecular characterization by RNA-seq. In brief, keratinocytes are grown in defined keratinocyte medium supplemented with growth factors until they are fully confluent. Differentiation is induced by close contacts between the keratinocytes and further stimulated by excluding growth factors in the medium. Using RNA-seq analyses, it is shown that both 1) differentiated keratinocytes exhibit distinct molecular signatures during differentiation and 2) the dynamic gene expression pattern largely resembles cells during epidermal stratification. As for comparison to normal keratinocyte differentiation, keratinocytes carrying mutations of the transcription factor p63 exhibit altered morphology and molecular signatures, consistent with their differentiation defects. In conclusion, this protocol details the steps for 2D in vitro keratinocyte differentiation and its molecular characterization, with an emphasis on bioinformatic analysis of RNA-seq data. Because RNA extraction and RNA-seq procedures have been well-documented, it is not the focus of this protocol. The experimental procedure of in vitro keratinocyte differentiation and bioinformatic analysis pipeline can be used to study molecular events during epidermal differentiation in healthy and diseased keratinocytes.

Presented here is a stepwise procedure for in vitro differentiation of human primary keratinocytes by contact inhibition followed by characterization at the molecular level by RNA-seq analysis.

Human primary keratinocytes are often used as in vitro models for studies on epidermal differentiation and related diseases. Methods have been reported ...