Week 2 at the Donohue Lab

Hey this is Meg Dalrymple, and I will be writing about my second week at the Donohue Lab, which mainly focuses in the evolutionary and genetic mechanisms behind germination at Duke University

The Autoclave

Walking into the lab on Monday of my second week, I felt much more prepared and comfortable than just 7 days prior. We still had one more day of censusing left to do and so me and Lien got started on it right away and finished pretty quickly. After that, we had a lot of dirty petri dishes that needed to be sterilized before we threw them out, since they contained biological waste (the germinating seeds). So, we headed over to the autoclave, which is a big machine that sterilizes things using heat and water. There are different types of cycles that you can run, depending on what you need to be sterilized. For the trash we used a setting called “gravity” which uses heat and water, but other dry cycles only use heat. After about an hour the trash was done so we took it out of the autoclave and to the dumpster. In the afternoon, we realized that we had cut the filter paper the wrong size for our experiment. However, the new uncut filter paper that Bri had ordered hadn’t arrived yet, so we continued to cut weigh boats and punch holes in them.

The next day on Tuesday, the filter paper came. However, I busy helping the other group in the lab prepare for later in the week so I couldn’t help cut the paper. I was busy preparing plates with which the group would seed (put seeds on the plates). This meant that I counted and laid out 900 plates. Next an undergraduate, Aman, made agar to be poured into all 900 plates. As I went to lunch he started pouring. When I returned, he told me the other agar was in the autoclave and that it would be done in about 5 minutes, and then he headed off to lunch. I went up to the autoclave and got the agar so I could begin pouring. About a half hour later, Aman returned and we continued to pour. In addition to pouring agar, the plates also had to be labeled. So as we poured, we labeled and organized the plates into the different seed genotypes. After we finished pouring the agar at one point, we realized that some of the plates we not solidifying. Aman figured out that because the liquid agar had been sitting for a while, the solution had separated and the top was mainly water, and the bottom was mainly agar. Therefore, we had to redo about 200 plates and make new agar to insure that we did it right. We finally finished pouring and labeling a couple hours later.

Cut filter paper

Then on Wednesday, Lien and I began to assemble our plates. This meant that first we would sterilize the cut weigh boats with ethanol (they couldn’t be autoclaved because they would melt). Next, because we cut slits in the strip of filter paper, we were able to create a loop out of it by locking the 2 ends together, using the slits. In this loop of filter paper, the weigh boat would slide in upside-down so that the bottom of the weigh boat was facing up. Then the weigh boat and filter paper would be put in a petri dish, lying flat. On the first day, we made about 120 dishes and then helped the other group seed.

On Thursday, our only goal was to finish making the dishes. We spent all morning and some of the afternoon working on it. Eventually however, we ran out of weigh boats and had to stop. This meant that we had to order more weigh boats, and eventually will have to cut and poke holes in them. We still have around 250 dishes that we need to make. Once we were unable to make any more dishes, we decided to autoclave some distilled water because we will need it for our experiment. For the rest of the day, we read articles.

The next day we wanted to make the solutions that had different water potentials since we will be seeding our experiment on Monday on dishes with those solutions. However, we needed to first autoclave empty bottles that would hold solutions. Therefore, while we were waiting for the autoclave to finish, we helped the other group seed until lunch. After lunch we began making the solutions. In order to change the water potential of solutions, we added a powder called polyethylene glycol (PEG). PEG is actually commonly used in medicines, in chemical spills, and in toothpastes and creams. It smells a lot like glue and when mixed together with water, it creates a soapy solution. We made 5 different water potentials by weighing out really large amounts of PEG and then mixing it with water. Once we were finished, Lien and I had to go to another discussion about a paper. However, this time the paper was far easier to understand, and I had already read it earlier in the spring. Therefore the meeting was a lot less stressful than the one we had the week before.

Overall I enjoyed this week because although I’m still not doing very exciting tasks, there is more variety to them now. I’ve learned how to do many new things this week, such as autoclaving and preparing dishes, making my research more interesting and enjoyable. In addition, everyone in the lab is still really friendly and enjoyable to work with, making the overall experience a good one.