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 ...

This is the fastest and right protocol to monitor the Drosophila gut acidification with robust and authentic results. This method will help to determine the role of gut acidification in multiple organisms. And this phenomenon is The simplicity of this technique is the main advantage.As such, it can be utilized for the non-model organisms. This method can monitor the acid release for many systems including the cell lines and 3D on live cultures. This technique is simple with minimal effort.Food containing Bromophenol blue should be prepared fresh. In addition, while dissection gut should not be stretched. Start arranging for the gut acidification monitoring assay with the preparation of the fly food with pH sensing Bromophenol blue or BPB dye.To do so, melt the fly food in a microwave and let it cool until lukewarm. Add one milliliter of 4%BPB to one milliliter of the lukewarm food with a mixing well. Using a pipette, add the fly food containing BPB into a single dot of approximately 200 microliters in the center of a petri dish.Next, collect zero to two-days-old non-virgin female Drosophila melanogaster flies, and allow the flies to recover on standard corn meal food. Before the experiment, starve the flies for 24 hours at room temperature in a vial containing a laboratory wipe tissue soaked with approximately two milliliters of deionized water. Transfer starved flies into a petri dish containing single dots of the freshly prepared fly food, supplemented with 2%BPB, to allow the flies to forage for four hours at room temperature while exposed to light.After four hours collect the flies, then proceed to surgically isolate the guts of the anesthetized flies in 1X PBS with forceps under a stereo microscope. Count the number of the flies that show robust BPB standing in the guts, and calculate the percentage using the equation. Following dissection, mount the samples in PBS onto a glass slide and place the prepared slide under the microscope.Then adjust the focus using the IPS. Once done, shut off the IPS to open the shutter for the camera. Following gut dissection, some Drosophila melanogaster female flies were found to produce acid as indicated by the yellow color in the CCR of the gut.Whereas the intestines of some flies were blue suggesting a failure of the flies to acidify their guts. Within 30 minutes, approximately 20%of flies had acidified the gut. After an hour, 40%of the gut guts showed acidification, while after two to three hours of feeding, the percentage of acidified guts increased to 60 to 70%Almost 90 to 95%of the guts were acidified when flies were fed for four hours.No difference in gut acidification was observed for two different temperature conditions. The efficiency of the gut acidification protocol was assessed in various Drosophila species. All the tested species showed robust gut acidification, suggesting the protocol can be applied to other organisms.The most important thing to remember, is to place the star flies into the petri plate with yeast and Bromophenol blue for four hours. This technique will help to understand the basic biology and cellular pathway involved in the gut acidification. It should also help to identify the drug target to create the diseases related to the gut acidification.

monitoring-gut-acidification-in-the-adult-drosophila-intestine

Research

Education

JoVE Journal

JoVE Core

Cell Biology

Biology

Unit 1

Membrane Transport and Active Transporters

SCIENTISTS IN ACTION

Extracting DNA from the Gut Microbes of the Termite (Zootermopsis Angusticollis) and Visualizing Gut Microbes

Termites are among the few animals known to have the capacity to subsist solely by consuming wood.  The termite gut tract contains a dense and species-rich microbial population that assists in the degradation of lignocellulose predominantly into acetate, the key nutrient fueling termite metabolism (Odelson &amp; Breznak, 1983).  Within these microbial populations are bacteria, methanogenic archaea and, in some ("lower") termites, eukaryotic protozoa. Thus, termites are excellent research subjects for studying the interactions among microbial species and the numerous biochemical functions they perform to the benefit of their host.  The species composition of microbial populations in termite guts as well as key genes involved in various biochemical processes has been explored using molecular techniques (Kudo et al., 1998; Schmit-Wagner et al., 2003; Salmassi &amp; Leadbetter, 2003). These techniques depend on the extraction and purification of high-quality nucleic acids from the termite gut environment.  The extraction technique described in this video is a modified compilation of protocols developed for extraction and purification of nucleic acids from environmental samples (Mor  et al., 1994; Berthelet et al., 1996; Purdy et al., 1996; Salmassi &amp; Leadbetter, 2003; Ottesen et al. 2006) and it produces DNA from termite hindgut material suitable for use as template for polymerase chain reaction (PCR).

Extracting DNA from the Gut Microbes of the Termite Zootermopsis Angusticollis and Visualizing Gut Microbes

This video illustrates the technique for extracting DNA from the species of microbes resident in the termite hindgut. The preparation of a wet mount slide, which is useful for visualizing the gut microbial community is also illustrated, and a tour through the species-rich gut environment is given.

Termites are among the few animals known to have the capacity to subsist solely by consuming wood.  The termite gut tract contains a dense and ...

Whole Cell Recordings from Brain of Adult Drosophila

In this video, we demonstrate the procedure for isolating whole brains from adult Drosophila in preparation for recording from single neurons. We begin by describing the dissecting solution and capture of the adult females used in our studies. The procedure for removing the whole brain intact, including both optic lobes, is illustrated. Dissection of the overlying trachea is also shown.  The isolated brain is not only small but needs special care in handling at this stage to prevent damage to the neurons, many of which are close to the outer surface of the tissue. We show how a special holder we developed is used to stabilize the brain in the recording chamber. A standard electrophysiology set up is used for recording from single neurons or pairs of neurons. A fluorescent image, viewed through the recording microscope, from a GAL4 line driving GFP expression (GH146) illustrates how projection neurons (PNs) are identified in the live brain. A high power Nomarski image shows a view of a single neuron that is being targeted for whole cell recording. When the brain is successfully removed without damage, the majority of the neurons are spontaneously active, firing action potentials and/or exhibiting spontaneous synaptic input. This in situ preparation, in which whole cell recording of identified neurons in the whole brain can be combined with genetic and pharmacological manipulations, is a useful model for exploring cellular physiology and plasticity in the adult CNS.

This video demonstrates the procedure for isolating whole brains from adult Drosophila in preparation for recording from single neurons using standard whole cell technology. It includes images of GFP labeled cells and neurons viewed during recording.

In this video, we demonstrate the procedure for isolating whole brains from adult Drosophila in preparation for recording from single neurons. We begin by ...

High-Resolution Video Tracking of Locomotion in Adult Drosophila Melanogaster

Flies provide an important model for studying complex behavior due to the plethora of genetic tools available to researchers in this field. Studying locomotor behavior in Drosophila melanogaster relies on the ability to be able to quantify changes in motion during or in response to a given task. For this reason, a high-resolution video tracking system, such as the one we describe in this paper, is a valuable tool for measuring locomotion in real-time. Our protocol involves the use of an initial air pulse to break the flies momentum, followed by a thirty second filming period in a square chamber. A tracking program is then used to calculate the instantaneous speed of each fly within the chamber in 10 msec increments. Analysis software then compiles this data, and outputs a variety of parameters such as average speed, max speed, time spent in motion, acceleration, etc. This protocol will discuss proper feeding and management of flies for behavioral tasks, handling flies without anesthetization or immobilization, setting up a controlled environment, and running the assay from start to finish.

The study of complex locomotor behavior in Drosophila melanogaster is dependent upon the ability to quantify changes in a given fly's movement. This article demonstrates how to do this using a high-resolution tracking system.

Flies provide an important model for studying complex behavior due to the plethora of genetic tools available to researchers in this field.  Studying ...

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained and restrained whole larvae. For direct control of the environment around the heart another approach utilizes the dissected larvae and removal of the internal organs in order to bathe the heart in desired compounds. The exposed heart also allows membrane potentials to be monitored which can give insight of the ionic currents generated by the myocytes and for electrical conduction along the heart tube. These approaches have various advantages and disadvantages for future experiments that are discussed. The larval heart preparation provides an additional model besides the Drosophila skeletal NMJ to investigate the role of intracellular calcium regulation on cellular function. Learning more about the underlying ionic currents that shape the action potentials in myocytes in various species, one can hope to get a handle on the known ionic dysfunctions associated to specific genes responsible for various diseases in mammals.

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various ways to monitor heart function in the larva of Drosophila for assessing questions dealing with the function of gap junctions, ion channel mutations, modulation of pacemaker activity and pharmacological studies.

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained  and  ...

Dissection of Oenocytes from Adult Drosophila melanogaster

In Drosophila melanogaster, as in other insects, a waxy layer on the outer surface of the cuticle, composed primarily of hydrocarbon compounds, provides protection against desiccation and other environmental challenges. Several of these cuticular hydrocarbon (CHC) compounds also function as semiochemical signals, and as such mediate pheromonal communications between members of the same species, or in some instances between different species, and influence behavior. Specialized cells referred to as oenocytes are regarded as the primary site for CHC synthesis. However, relatively little is known regarding the involvement of the oenocytes in the regulation of the biosynthetic, transport, and deposition pathways contributing to CHC output. Given the significant role that CHCs play in several aspects of insect biology, including chemical communication, desiccation resistance, and immunity, it is important to gain a greater understanding of the molecular and genetic regulation of CHC production within these specialized cells. The adult oenocytes of D. melanogaster are located within the abdominal integument, and are metamerically arrayed in ribbon-like clusters radiating along the inner cuticular surface of each abdominal segment. In this video article we demonstrate a dissection technique used for the preparation of oenocytes from adult D. melanogaster. Specifically, we provide a detailed step-by-step demonstration of (1) how to fillet prepare an adult Drosophila abdomen, (2) how to identify the oenocytes and discern them from other tissues, and (3) how to remove intact oenocyte clusters from the abdominal integument. A brief experimental illustration of how this preparation can be used to examine the expression of genes involved in hydrocarbon synthesis is included. The dissected preparation demonstrated herein will allow for the detailed molecular and genetic analysis of oenocyte function in the adult fruit fly.

Dissection of Oenocytes from Adult Drosophila melanogaster

In insects, the oenocytes produce cuticular hydrocarbon compounds. These compounds protect against desiccation and facilitate chemical communication. Here we demonstrate a dissection technique used to isolate the oenocytes from adult Drosophila melanogaster, and illustrate how this preparation can be utilized to study genes involved in hydrocarbon synthesis.

In Drosophila melanogaster, as in other insects, a waxy layer on the outer surface of the cuticle, composed primarily of hydrocarbon compounds, provides ...

Insulin Injection and Hemolymph Extraction to Measure Insulin Sensitivity in Adult Drosophila melanogaster

Conserved nutrient sensing mechanisms exist between mammal and fruit fly where peptides resembling mammalian insulin and glucagon, respectively function to maintain glucose homeostasis during developmental larval stages 1,2. Studies on largely post-mitotic adult flies have revealed perturbation of glucose homeostasis as the result of genetic ablation of insulin-like peptide (ILP) producing cells (IPCs) 3. Thus, adult fruit flies hold great promise as a suitable genetic model system for metabolic disorders including type II diabetes. To further develop the fruit fly system, comparable physiological assays used to measure glucose tolerance and insulin sensitivity in mammals must be established. To this end, we have recently described a novel procedure for measuring oral glucose tolerance response in the adult fly and demonstrated the importance of adult IPCs in maintaining glucose homeostasis 4,5. Here, we have modified a previously described procedure for insulin injection 6 and combined it with a novel hemolymph extraction method to measure peripheral insulin sensitivity in the adult fly. Uniquely, our protocol allows direct physiological measurements of the adult fly's ability to dispose of a peripheral glucose load upon insulin injection, a methodology that makes it feasible to characterize insulin signaling mutants and potential interventions affecting glucose tolerance and insulin sensitivity in the adult fly.

Insulin Injection and Hemolymph Extraction to Measure Insulin Sensitivity in Adult Drosophila melanogaster

Conserved insulin signaling pathways found in the fruit fly Drosophila melanogaster make this organism a potential tool for modeling metabolic disorders including type II diabetes. To this end, it is critical to establish physiological assays to effectively measure systemic insulin action in peripheral glucose disposal in the adult fly.

Conserved nutrient sensing mechanisms exist between mammal and fruit fly where peptides resembling mammalian insulin and glucagon, respectively function ...

Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish water and sediment. The choice of biological indicators must be based on reliable scientific knowledge and, possibly, on the availability of standardized procedures. In this article, we present a standardized protocol that used the marine crustacean Artemia to evaluate the toxicity of chemicals and/or of marine environmental matrices. Scientists propose that the brine shrimp (Artemia) is a suitable candidate for the development of a standard bioassay for worldwide utilization. A number of papers have been published on the toxic effects of various chemicals and toxicants on brine shrimp (Artemia). The major advantage of this crustacean for toxicity studies is the overall availability of the dry cysts; these can be immediately used in testing and difficult cultivation is not demanded1,2. Cyst-based toxicity assays are cheap, continuously available, simple and reliable and are thus an important answer to routine needs of toxicity screening, for industrial monitoring requirements or for regulatory purposes3. The proposed method involves the mortality as an endpoint. The numbers of survivors were counted and percentage of deaths were calculated. Larvae were considered dead if they did not exhibit any internal or external movement during several seconds of observation4. This procedure was standardized testing a reference substance (Sodium Dodecyl Sulfate); some results are reported in this work. This article accompanies a video that describes the performance of procedural toxicity testing, showing all the steps related to the protocol.

Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana

This study concerns the development and standardization of a valuable methodological protocol to determine long-term (14 days) lethal toxicity exerted by chemical substances, industrial wastewater or sewage and liquid environmental samples on the saltwater crustacean, Artemia franciscana.

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish ...

Live Imaging of Apoptotic Cell Clearance during Drosophila Embryogenesis

The proper elimination of unwanted or aberrant cells through apoptosis and subsequent phagocytosis (apoptotic cell clearance) is crucial for normal development in all metazoan organisms. Apoptotic cell clearance is a highly dynamic process intimately associated with cell death; unengulfed apoptotic cells are barely seen in vivo under normal conditions. In order to understand the different steps of apoptotic cell clearance and to compare 'professional' phagocytes - macrophages and dendritic cells to 'non-professional' - tissue-resident neighboring cells, in vivo live imaging of the process is extremely valuable. Here we describe a protocol for studying apoptotic cell clearance in live Drosophila embryos. To follow the dynamics of different steps in phagocytosis we use specific markers for apoptotic cells and phagocytes. In addition, we can monitor two phagocyte systems in parallel: 'professional' macrophages and 'semi-professional' glia in the developing central nervous system (CNS). The method described here employs the Drosophila embryo as an excellent model for real time studies of apoptotic cell clearance.

Live Imaging of Apoptotic Cell Clearance during Drosophila Embryogenesis

Here we describe an effective method for studying dynamics of apoptotic cell clearance in vivo. This method employs live Drosophila embryos as a powerful model for monitoring phagocytosis of apoptotic cells using specific labeling of apoptotic cells and phagocytes.

The  proper elimination of unwanted or aberrant cells through apoptosis and  subsequent phagocytosis (apoptotic cell clearance) is crucial for normal  ...

The Tomato/GFP-FLP/FRT Method for Live Imaging of Mosaic Adult Drosophila Photoreceptor Cells

The Drosophila eye is widely used as a model for studies of development and neuronal degeneration. With the powerful mitotic recombination technique, elegant genetic screens based on clonal analysis have led to the identification of signaling pathways involved in eye development and photoreceptor (PR) differentiation at larval stages. We describe here the Tomato/GFP-FLP/FRT method, which can be used for rapid clonal analysis in the eye of living adult Drosophila. Fluorescent photoreceptor cells are imaged with the cornea neutralization technique, on retinas with mosaic clones generated by flipase-mediated recombination. This method has several major advantages over classical histological sectioning of the retina: it can be used for high-throughput screening and has proved an effective method for identifying the factors regulating PR survival and function. It can be used for kinetic analyses of PR degeneration in the same living animal over several weeks, to demonstrate the requirement for specific genes for PR survival or function in the adult fly. This method is also useful for addressing cell autonomy issues in developmental mutants, such as those in which the establishment of planar cell polarity is affected.

The Tomato/GFP-FLP/FRT Method for Live Imaging of Mosaic Adult Drosophila Photoreceptor Cells

The Tomato/GFP-FLP/FRT method involves visualizing mosaic photoreceptor cells in living Drosophila. It can be used to follow individual photoreceptor cell fates in the retina for days or weeks. This method is ideal for studies of retinal degeneration and neurodegenerative diseases or photoreceptor cell development.

The Drosophila eye is widely used as a model  for studies of development and neuronal degeneration. With the powerful mitotic  recombination technique, ...

Gavaging Adult Zebrafish

The zebrafish has become an important in vivo model in biomedical research. Effective methods must be developed and utilized to deliver compounds or agents in solutions for scientific research. Current methods for administering compounds orally to adult zebrafish are inaccurate due to variability in voluntary consumption by the fish. A gavage procedure was developed to deliver precise quantities of infectious agents to zebrafish for study in biomedical research. Adult zebrafish over 6 months of age were anesthetized with 150 mg/L of buffered MS-222 and gavaged with 5 &mu;l of solution using flexible catheter implantation tubing attached to a cut 22-G needle tip. The flexible tubing was lowered into the oral cavity of the zebrafish until the tip of the tubing extended past the gills (approximately 1 cm). The solution was then injected slowly into the intestinal tract. This method was effective 88% of the time, with fish recovering uneventfully. This procedure is also efficient as one person can gavage 20-30 fish in one hour. This method can be used to precisely administer agents for infectious diseases studies, or studies of other compounds in adult zebrafish.

The increasing use of zebrafish as an animal model requires the development of effective methods for the delivery of known quantities of compounds and solutions. The gavage procedure described below allows for the oral delivery of precise volumes of solution reliably, safely and efficiently to adult zebrafish.

The zebrafish has become an important in vivo model in biomedical research. Effective methods must be developed and utilized to deliver compounds or ...