Tools of the Trade

A late post this week, but I want to spend time showing off three items that are vital to the work I am currently doing. I have spent the past couple of weeks moving back and forth between my two labs, working on microplastics extractions, sediment processing, and nematode extractions and counting, with my current focus being nematode counting until I get some more materials into the lab. Counting nematodes in a sample of sediment can be an extreme challenge due to their abundance, size, and natural color--they are transparent to help them blend into their environment. There are four items (two not pictured) that help to make nematode counting and slide preparations really manageable, though both processes are still time consuming. The first item is a dye we use called Rose Bengal, which is a sodium salt solution that is a red/pink color, often used to identify retinal damage in humans. However, Rose Bengal also stains dead cells and mucus, which is why it is used for nematode counting, since the nematodes in my samples are dead when I get them back to the lab. Here (right) you can see my point of view through the stereomicroscope looking at a section of a sediment sample. The sediment grains are in brown, there are some salt crystals that are clear, and in the center there is a nematode stained with the Rose Bengal. The stain makes sure that the nematodes stand out among the various other material in the sediment samples. Other dead meiofauna get stained as well, but the shape of nematodes is so identifiable that it is very hard to grab the wrong animal from the sample.

The second, third, and fourth items are a team of tools that are probably more important than the stain. Sometimes the stain doesn't work fully and I may have to use even more care while going through a sample to look for transparent nematodes. However, the team of items here are vital to nematode counting: a counting dish, a handheld counter, and an extraction needle/hook. To count the nematodes in a sample, I pour the sample into a petri dish that is attached to a counting sticker dividing the petri dish into numbered squares. The squares allow me to move in numerical order throughout the dish and give me a smaller area to focus on when counting nematodes, rather than trying to count the whole sample at once. When I find a nematode like the one in the picture above, I use the handheld counter to mark that I spotted a nematode, and then I remove that nematode from the sample to be put on slides for later identification. The extraction needle/hook is like a pencil with a tiny needle on the end (shown below) that has a bend on which nematodes can be rested or caught. I scoop underneath the nematode, get it rested on the hook, and then transfer it to a separate dish to make microscope slides. Sometimes, there can be an unruly amount of nematodes in a sample; this week I counted more than 1,000 nematodes in a single sample. Because there are too many nematodes to identify, considering that I have close to 700 samples for my research, I only take the first 100 nematodes from each sample but I do count the rest. The handheld counter helps me keep track of every little animal that I see, and painstaking diligence with the extraction needle makes sure that I have enough nematodes to identify to answer important questions in my research.

Lastly, how did I learn all these things, and where does one go to school to learn all of these steps? I had never used any of these tools or materials, with the exception of a handheld counter, until coming to FSU. Dr. Ingels taught me how to process samples, including the purpose for the Rose Bengal, and he also trained me how to catch larger meiofauna on a tool similar to the extraction hook. After practicing on approximately 40-50 samples, I then moved on to extracting nematodes, and I practiced more. I will say that the extracting and counting step of the research can be monotonous, so thank goodness for my music playlist and no complaints from other researchers at the lab when I'm singing along.

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