Authors: Andrew Call
Mentors: John Chaston
Insitution: Brigham Young University
The main goal for this project is to confirm previous predictions of specific genes that may influence flies’ dietary preference to consume lactic acid bacteria (LAB). The preference of LAB is a normal phenotype that flies have, because the bacteria is essential for their gut microbiota. A previous genome-wide association study (GWAS) by another student in my mentor’s lab predicted genes that lead flies to prefer to consume diets that have live LAB. This genetically determined fly phenotype was measured by calculating the frequency and number of times the flies would choose the LAB inoculated diet over a control diet. My role will be to test if 7 genes have the influence predicted by this previous analysis.
The experiment will follow close with the one previously performed by the student who predicted the genes I’m testing. I’ll be using a flyPAD which has a small arena (cage) that will hold one fly. Inside that arena are 2 wells that contain food. These wells have sensors attached to them, so each time the fly takes a sip of food, an electronic signal will be sent to a computer that keeps track of the number of sips from each well, the duration of each sip taken and time in between each sip and graph all the results taken for comparison between a control group and the test groups. I will starve 48 female mutant drosophila melanogaster for 3 hours prior to the experiment and then place them inside the flyPAD where I have previously placed 1 μl of 1:1 yeast-glucose diets in each well, however I will inoculate 0.05 μl of LAB in one of the diets. I will track each sip the flies take from each of the two foods for 1 hour. To measure accurately, there will be 2 controls also being tested. I will use flies that do not contain the genetic mutation and I will also have control arenas where both food wells do not contain LAB.
I expect that any mutant that has a reduced preference for LAB-inoculated diet relative to the control diet represents a validated prediction of the previous study. In some cases, there may be no variation in preference for the control or LAB-inoculated diet, indicating a gene that does not contribute to fly preference for LAB in the diet. If none of the mutants tested validate the genome-wide association predictions, I will go back to the gene list and select one additional subset of genes to test if these influence the genetic prediction. We previously focused on genes that had multiple hits in the previous experiment, regardless of how significant the predictions were. In this second round, I will simply select the ten most significant remaining genes. Overall, this project will help confirm the previously selected genes with their association with a diet preference of lactic acid bacteria, improving the gut microbiota of Drosophila melanogaster.