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 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 exper…

Representative 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 percentage of flies showing gut acidification fed for different durations over 4 h. Representative gut images of an acidified gut and a…

Materials

Bromophenol blue	Sigma-Aldrich		B0126
D. simulans	Drosophila Species Stock Center at the University of California		Riverside California1 (https://www.drosophilaspecies.com/)
D. erecta	Drosophila Species Stock Center at the University of California		Dere cy1(https://www.drosophilaspecies.com/)
D. pseudoobscura	Drosophila Species Stock Center at the University of California		Eugene, Oregon(https://www.drosophilaspecies.com/)
D. mojavensis	Drosophila 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 Drosophila 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