Name: monitoring gut acidification in the adult drosophila intestine
Uploaded: 2021-10-11T14:00:00
Description: Watch this Scientific Journal Video about Monitoring Gut Acidification in the Adult Drosophila Intestine at JoVE.com

The authors acknowledge that support for work in the author&#39;s laboratory is provided by an HHMI Faculty Scholar Award and startup funds from the Children&#39;s Research Institute at UT Southwestern Medical Center.

NOTE: The standard laboratory line Oregon R was used as a WT control. All flies were reared on standard cornmeal-molasses medium (containing molasses, agar, yeast, cornmeal, tegosept, propionic acid, and water) at room temperature with 12/12 h light/dark circadian rhythm.
1. Preparing for the assay
<ol>
	<li>Collect female flies (0-2 days old, non-virgin) under CO2 anesthesia and allow them to recover on standard cornmeal food for at least 3 days before experiment...

<ol>
	<li>Hollander, 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+composition+and+mechanism+of+formation+of+gastric+acid+secretion.">The composition and mechanism of formation of gastric acid secretion.</a> Science. 110 (2846), 57-63 (1949).</li><li>Forte, J. G., Zhu, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apical+recycling+of+the+gastric+parietal+cell+H,+K-ATPase.">Apical recycling of the gastric parietal cell H, K-ATPase.</a> Annual Review of Physiology. 72, 273-296 (2010).</li><li>Samuelson, L. C., Hinkle, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insights+into+the+regulation+of+gastric+acid+secretion+through+analysis+of+genetically+engineered+mice.">Insights into the regulation of gastric acid secretion through analysis of genetically engineered mice.</a> Annual Review of Physiology. 65, 383-400 (2003).</li><li>Yao, X., Forte, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+biology+of+acid+secretion+by+the+parietal+cell.">Cell biology of acid secretion by the parietal cell.</a> Annual Review of Physiology. 65, 103-131 (2003).</li><li>Driver, I., Ohlstein, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specification+of+regional+intestinal+stem+cell+identity+during+Drosophila+metamorphosis.">Specification of regional intestinal stem cell identity during Drosophila metamorphosis.</a> Development. 141 (9), 1848-1856 (2014).</li><li>Overend, , 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=Molecular+mechanism+and+functional+significance+of+acid+generation+in+the+Drosophila+midgut.">Molecular mechanism and functional significance of acid generation in the Drosophila midgut.</a> Scientific Reports. 6, 27242 (2016).</li><li>Shanbhag, S., Tripathi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epithelial+ultrastructure+and+cellular+mechanisms+of+acid+and+base+transport+in+the+Drosophila+midgut.">Epithelial ultrastructure and cellular mechanisms of acid and base transport in the Drosophila midgut.</a> Journal of Experimental Biology. 212, 1731-1744 (2009).</li><li>Dubreuil, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Copper+cells+and+stomach+acid+secretion+in+the+Drosophila+midgut.">Copper cells and stomach acid secretion in the Drosophila midgut.</a> International Journal of Biochemistry and Cell Biology. 36 (5), 745-752 (2004).</li><li>Martorell, , 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=Conserved+mechanisms+of+tumorigenesis+in+the+Drosophila+adult+midgut.">Conserved mechanisms of tumorigenesis in the Drosophila adult midgut.</a> PLoS ONE. 9 (2), 88413 (2014).</li><li>Strand, M., Micchelli, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regional+control+of+Drosophila+gut+stem+cell+proliferation:+EGF+establishes+GSSC+proliferative+set+point+&amp;+controls+emergence+from+quiescence.">Regional control of Drosophila gut stem cell proliferation: EGF establishes GSSC proliferative set point &amp; controls emergence from quiescence.</a> PLoS One. 8 (11), 80608 (2013).</li><li>Storelli, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+perpetuates+nutritional+mutualism+by+promoting+the+fitness+of+its+intestinal+symbiont+Lactobacillus+plantarum.">Drosophila perpetuates nutritional mutualism by promoting the fitness of its intestinal symbiont Lactobacillus plantarum.</a> Cell Metabolism. 27 (2), 362-377 (2018).</li><li>Abu, F., 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=Communicating+the+nutritional+value+of+sugar+in+Drosophila.">Communicating the nutritional value of sugar in Drosophila.</a> Proceedings of the National Academy of Sciences of the United States of America. 115 (12), 2829-2838 (2018).</li><li>Blecker, U., Gold, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gastritis+and+ulcer+disease+in+childhood.">Gastritis and ulcer disease in childhood.</a> European Journal of Pediatrics. 158 (7), 541-546 (1999).</li></ol>

A critical step in this protocol is the proper dissection of the gut to visualize the CCR for the acidification phenotype. The acid released from the copper cells is confined to the CCR when the gut is intact. However, during dissection, leakage caused by rupture of the intestine can lead to diffusion of acid from the CCR and result in a gut mistakenly scored as a negative for acidification. In addition, the yellow color indicative of acidification fades within 5-10 min after dissection, underscoring the importance of sc...

In the insect gut, copper cells share cellular and functional similarities with the acid-producing gastric parietal cells (also known as oxyntic) of the mammalian stomach. This group of cells releases acid into the intestinal lumen. The function of acid secretion and anatomy is evolutionarily conserved. The major components of the discharged acid are hydrochloric acid and potassium chloride. The chemical mechanism of acid formation in the cells depends on carbonic anhydrase. This enzyme generates a bicarbonate ion from CO2 and water, which liberates a hydroxyl ion that is then discharged into the lumen through a proton pump in exchange for potassium. Chloride and potassium ions are transported into the lumen by conductance channels resulting in the formation of hydrochloric acid and potassium chloride, the main component of gastric juice1,2,3,4.
Although the mechanisms of acid formation are well understood, much less is known about the physiological mechanisms that regulate acid secretion. The goal of developing this method is to help better delineate the cellular pathways that coordinate acid formation and secretion and determine the role of acid in mediating intestinal physiology and homeostasis. The rationale behind the development and use of this technique is to provide a consistent and reliable method to study the process of gut acidification in Drosophila and non-model organisms. Although a standard protocol for determining Drosophila midgut acidification currently exists2,5,6, significant variability was observed in the extent of acidification in wild-type (WT) flies while using this protocol for studying copper cell function. To understand the basis for this observed variability and obtain consistent results, several aspects of the standard protocol were optimized as described below.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Bromophenol blue</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td>B0126</td>
		</tr>
		<tr>
			<td>cellSens software</td>
			<td>Olympus</td>
			<td></td>
			<td>Image aqusition (https://www.olympus-lifescience.com/en/software/cellsens)</td>
		</tr>
		<tr>
			<td>D. simulans</td>
			<td>Drosophila Species Stock Center at the University of California</td>
			<td></td>
			<td>Riverside California1 (https://www.drosophilaspecies.com/)</td>
		</tr>
		<tr>
			<td>D. erecta</td>
			<td>Drosophila Species Stock Center at the University of California</td>
			<td></td>
			<td>Dere cy1(https://www.drosophilaspecies.com/)</td>
		</tr>
		<tr>
			<td>D. pseudoobscura</td>
			<td>Drosophila Species Stock Center at the University of California</td>
			<td></td>
			<td>Eugene, Oregon(https://www.drosophilaspecies.com/)</td>
		</tr>
		<tr>
			<td>D. mojavensis</td>
			<td>Drosophila Species Stock Center at the University of California</td>
			<td></td>
			<td>Chocolate Mountains, California (https://www.drosophilaspecies.com/)</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Inox Biology</td>
			<td></td>
			<td>Catalog# 11252-20</td>
		</tr>
		<tr>
			<td>Fuji</td>
			<td>Fuji</td>
			<td></td>
			<td>Image processing (https://hpc.nih.gov/apps/Fiji.html)</td>
		</tr>
		<tr>
			<td>Glass slide</td>
			<td>VWR</td>
			<td></td>
			<td>Catalog#16005-108</td>
		</tr>
		<tr>
			<td>Kim wipes Tissue</td>
			<td>Kimtech</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope and camera</td>
			<td>Olympus SZ61 microscope equipped with an Olympus D-27 digital camera</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Oregon R</td>
			<td>Bloomington Drosophila Stock</td>
			<td></td>
			<td>(https://bdsc.indiana.edu/ # 2376)</td>
		</tr>
		<tr>
			<td>Petri dishes</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td>Catalog #FB0875713A</td>
		</tr>
		<tr>
			<td>Phosphate-buffered Saline (PBS)</td>
			<td>HyClone</td>
			<td></td>
			<td>Catalog # SH30258.01</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Olympus SZ51</td>
			<td></td>
			<td>Visual magnification</td>
		</tr>
	</tbody>
</table>

monitoring gut acidification in the adult drosophila intestine

The fruit fly midgut consists of multiple regions, each of which is composed of cells that carry out unique physiological functions required for the proper functioning of the gut. One such region, the copper cell region (CCR), is localized to the middle midgut and consists, in part, of a group of cells known as copper cells. Copper cells are involved in gastric acid secretion, an evolutionarily conserved process whose precise role is poorly understood. This paper describes improvements in the current protocol used to assay for acidification of the adult Drosophila melanogaster gut and demonstrates that it can be used on other species of flies. In particular, this paper demonstrates that gut acidification is dependent on the fly's nutritional status and presents a protocol based on this new finding. Overall, this protocol demonstrates the potential usefulness of studying Drosophila copper cells to uncover general principles underlying the mechanisms of gut acidification.

We starved Oregon R female flies for more than 20 h and then fed them food supplemented with BPB (2%) for ~12 h, as described previously7,8,9,10,11. Bromophenol blue (BPB) is a pH-sensing dye. It changes from yellow at pH 3.0 to blue at pH 4.6 and above. Following gut dissection, as previously reported, some flies were found to produce acid as indicated by yel...

Watch this Scientific Journal Video about Monitoring Gut Acidification in the Adult Drosophila Intestine at JoVE.com

Monitoring Gut Acidification in the Adult Drosophila Intestine

Here, we present a standardized protocol for monitoring gut acidification in Drosophila melanogaster with optimal output. We first use this protocol for gut acidification monitoring in Drosophila melanogaster and then demonstrate its use in non-model Drosophila species.

Monitoring Gut Acidification in the Adult Drosophila Intestine

The fruit fly midgut consists of multiple regions, each of which is composed of cells that carry out unique physiological functions required for the ...

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