Pre-Trials Continued

We have made extensive progress on our research in the past few weeks!

​As mentioned before, our D. magna from Carolina Biological came in in the beginning of January, so we have set up two starter cultures to prevent population wipeout.

Each starter culture is filled with two liters of stock solution - a combination of DI water and compounds recommended by Cornell University - and administered .131g of pulverized Daphnia Food (Carolina Biological) every Monday, Wednesday, and Friday. Each culture is also fed in the case of a water change, which occurs once a week, as during these cleanings, all food is removed. Finally, we have incorporated a heating pad donated by a peer advisor in order to keep our culture temperature between 20-25 degrees C.

The cultures are proliferating rapidly, with a difference of hundreds in just over a week. Pictured below is Starter Culture A on the day that we received our shipment of D. magna from Carolina Biological and then exactly seven days later, after the D. magna had time to produce offspring.

With all of these additional D. magna, we have been able to begin testing our blue light technique in order to separate the juvenile D. magna from the adults. Previous research suggested that all D. magna are attracted to blue light, particularly at a wavelength of 470 nm. Therefore, we constructed a separation tank using a nylon net with 500um holes - large enough to allow the juveniles to pass through, but small enough to stop the passage of the adults. This allows us to age-synchronize our D. magna for our experimental trials, which rely on the assumption that all of the D. magna are similar ages.

This technique has proved largely successful. Although not all juvenile D. magna chose to pass through the net to the other side, enough did travel through to supply us with sufficient D. magna for our first official pre-trial. Here, we transferred 60 juvenile D. magna from the far side of the tank into 4 containers filled with 180 mL of their appropriate concentration of EE2 (4 containers of 15 each). Due to the limits of our analytical balance, these concentrations were mixed in larger volumes by combining 997 mL of stock solution (compounds + DI) with 3 mL of DMSO and the appropriate measurement of EE2 - .001g for LOW, .002g for high, and .003g in 2L instead of 1L for MEDIUM. We then bottled the extra concentrations for later use. This trial is still running and will be analyzed for mortality rates on Tuesday.

Finally, we also had a brief opportunity to image additional D. magna this last Friday. During this time under the microscope, we witnessed the release of a juvenile D. magna from the brood chamber of an adult female, which is essentially equivalent to its "birth". We were also able to image the heart and distinguish differences between the male and female D. magna, including the fact that it is much easier to image the heart of a male than a female.

We plan to start our experimental trials in just a few weeks or less, depending on the results of the ongoing trial. In the meantime, thanks for continuing to follow our research! Updates to follow.