Collecting Fruit Flys

Hello again,

Recently I have spent a lot of time on the confocal microscope taking pictures of embryonic gonads to determine the temporal and spatial expression pattern of the Tj-Gal4 driver and Upd-Gal4 driver.  The main project that I am working on this summer deals with characterizing various Gal4-UAS gene expression drivers.  It is important to understand how these drivers work because they are an important tool for scientists to study their gene of interest in fruit flies.  The pictures are quite colorful, with an array of red, green, and blue colors illuminating various cells.  The colors aren’t naturally there though, they only show up after a procedure known as immunostaining which allows us to visualize specific proteins in the embryo.  If you wanted to see some of the pictures there are some that I took on a poster hanging up right outside our lab.  It can be quite time consuming taking these pictures because in order to develop a 3D image of a gonad using the confocal microscope the camera has to take a series of photos consisting of all the different planes of the gonad.  This often takes anywhere from 2 to 5 minutes per gonad.  Besides taking pictures of the Tj-Gal4 driver, there are 8 other drivers that have to be characterized for this project.

It takes about 15 days to perform all of the procedures needed to make a slide that can be analyzed under the confocal microscope.  The most time consuming procedure is collecting virgin female flies to be used in the matings.  Female flies store sperm in a sac called the spermatheca.  If we wanted to set up a mating between two different types of flies, we have to ensure that the females are virgin so they won’t have sperm stored from other types of male flies.  If we mess up at this point we can have contamination, which will lead to inaccurate results and a waste of a large amount of time.  Virgin females have distinct physical features which remain visible for multiple hours after they are born.

virgin female comparison to regular fly.tifVirgin meconium.tif

The picture on the top shows a virgin female on the left next to a non-virgin female on the right.  You can easily notice that the virgin female is much larger and whiter than the non-virgin.  The virgin female will look like the fly to its right in a few hours after all of the water that is built up in its abdomen spreads throughout the fly, resulting in the wings expanding.  The bottom picture shows two virgin females lying on their back.  The other sign that a fly is virgin is a tiny black spot located on their abdomen.  This black spot is known as a meconium, and it is composed of the remains of the fly’s last meal before pupating.

At one point this summer I had to collect virgin females from five different fly lines at the same time.  That lasted for about a week three times a day.  With that many fly lines it took about 20 minutes total at each collection.  Although that is the shortest procedure I perform in lab, it is definitely the procedure I spend the most amount of time doing throughout the whole year.   By the end of the week I hoped to collect at least 80 virgin females to set up for a mating with 1/3 the number of males.  From such mating I collect embryos at different age points for analysis of their gonads under the confocal microscope.

Although much of what I do in lab is repetitive and time consuming, getting pretty pictures of gonads and the different types of cells/stem cells inside of it makes it all worth it.  I really don’t have many exciting stories to tell about my experiences performing these procedures, so the pictures of the gonads that I have taken located outside of my lab will have to suffice.

Marc