Gut Acidification Monitoring Assay: A Technique to Study the Acidification of the Intestinal Lumen in Drosophila using Bromophenol Blue Dye

Abstract

Source: Abu, F., et al. Monitoring Gut Acidification in the Adult Drosophila Intestine. J. Vis. Exp. (2021).

This video demonstrates an assay to monitor gut acidification in Drosophila flies. After the ingestion of food supplemented with a pH indicator dye, the acidification of the intestinal lumen results in a change in the color of the dye. Visual inspection of the digestive tract of the flies to examine the color change provides evidence of acidification.

Protocol

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

1. 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 experiments.
2. Starve the flies for ~24 h at room temperature (~23 °C) in vials containing a laboratory wipe tissue soaked with ~2 mL of deionized ....

Results

Figure 1: Gut acidification monitoring. (A) Schematic drawing of feeding arena. The blue dot represents fly food with bromophenol blue (a pH-indicating dye). Other spots represent fruit flies. (B) Graphical representation of p.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Bromophenol blue	Sigma-Aldrich		B0126
<em>D. simulans</em>	<em>Drosophila </em>Species Stock Center at the University of California		Riverside California1 (https://www.drosophilaspecies.com/)
<em>D. erecta</em>	<em>Drosophila </em>Species Stock Center at the University of California		Dere cy1(https://www.drosophilaspecies.com/)
<em>D. pseudoobscura</em>	<em>Drosophila</em> Species Stock Center at the University of California		Eugene, Oregon(https://www.drosophilaspecies.com/)
<em>D. mojavensis</em>	<em>Drosophila </em>Species Stock Center at the University of California		Chocolate Mountains, California (https://www.drosophilaspecies.com/)
Forceps	Inox Biology		Catalog# 11252-20
Kim wipes Tissue	Kimtech
Oregon R	Bloomington <em>Drosophila </em>Stock		(https://bdsc.indiana.edu/ # 2376)
Petri dishes	Fisher Scientific		Catalog #FB0875713A
Phosphate-buffered Saline (PBS)	HyClone		Catalog # SH30258.01
Stereomicroscope	Olympus SZ51		Visual magnification