Back in the lab

There are exactly two seasons in Massachusetts: no-sock season and neck-warmer season. My wardrobe is dichotomous in this state. Either I'm hanging out on my boat in a breezy top and sandals, or I'm layered up in wool socks and sweaters. There is very little in-between. 

After returning from Palau, I had the abrupt adjustment from no-sock mode to neck-warmer mode. I switched from coral biologist to autumnal researcher, tropical diver to bundled cyclist. The transition was swift and complete. 

The nice thing about research in Palau is that the samples come straight back with me to Massachusetts - no waiting for boxes to show up. I've already started digging into the samples. The most important step is to determine the sex and the genetic lineage for all the Porites lobata samples I collected. We'll spawn this species when the team goes back in the spring, so we need to know the identity of the eligible parents that I tagged. 

The analysis is proceeding in two ways: first, I'm extracting DNA from all the Porites samples. I did the same process in early 2019, so it's just about routine for me by now. There are a lot of steps, but at least I know what I'm doing. If you're interested in reading more about DNA extraction, check out posts from January - March 2019.

The other part of the analysis involves histology. My old PhD lab in Oregon used to do a lot of histology for reproductive studies, but I never did any of it myself. I collaborated with my old lab mate, Caitlin, on a histological analysis of Arctic hydroids last year, so you might remember the technique. You basically embed the tissue you're analyzing in paraffin wax, add a couple different dyes to color specific cellular structures, and then slice the wax block thinly and mount the slices on slides. You end up with a series of microscope slides with thin slices that show cellular structures in a high level of detail.

Coral samples getting their calcium carbonate dissolved away.
Photo by JK Da-Anoy.

Corals have one complicating factor for histology: they're made of calcium carbonate. You can't slice through calcium carbonate very easily, so you have to dissolve the hard parts before embedding the tissue in wax. How do you dissolve calcium carbonate without impacting the biological tissue it contains? Good question. It involves a lot of patience and some hydrochloric acid. 

The histology is being conducted in my collaborator's lab at Boston University. Her student, JK, sent me some photos of the process, and they're pretty cool! You can see little bubbles forming around the bits of coral because calcium carbonate is converted to carbon dioxide as it reacts with the acid. 

Once the calcium carbonate is gone, JK will embed the tissue, dye it, slice it, and mount it. I really hope we'll be able to tell the sex of each coral when he's done!