Monday, December 29, 2008

Ask Me About Black Darter Reproduction!

I finally had a chance to sit down this afternoon and do work on our black darter manuscript, boiling down Rachel's thesis. It's starting to look & read like a journal-ready article. Without a title page or references it's 32 pages. Partially this is because I've included a bunch of figures of microscopic images of darter testes and ovaries in various states, to illustrate that the histological approaches Rachel used give unusually clear views of the size and arrangement of individual gonads. The work tracks and compares two populations of darters from January - April, and finds clear differences between them in length and weight, timing of gonadal maturation, and number of ripe eggs available for a clutch of eggs. The population from a scuzzy-looking urban creek was bigger with more eggs, but the population from a relatively clean, intact rural creek exhibited seasonal maturation earlier. So it's a lot of information with a lot of statistical treatment to weave together. My current plan is to submit it to one of my favorite journals, Southeastern Naturalist. It's a big article for them, but I plan on paring it down some before submission.

Friday, December 26, 2008

When Fedex Overnight Isn't

Kris shipped out his latest mummichog DNA samples Monday morning to MC Labs in San Diego. This time he shipped them Fedex Overnight. They hadn't been received in San Diego as of mid-afternoon on Wednesday, and I can only hope they're there now. At least that's faster than UPS Ground... hah! Otherwise things are quiet, I'm toying with the idea of further work on Rachel's black darter thesis-to-article project. If anyone sees Rachel, ask her to get in touch with me. Thanks!

Monday, December 22, 2008

We're Resubmitting Kris' Mummichog DNA Samples

Kris has re-done and re-shipped his mummichog DNA PCR products back to MC Labs in San Diego. His first shipment went UPS Surface, which took 6 days to get there(!). The resulting product wasn't quite usable. So, he re-did the PCR yesterday and today, and is shipping it to MC Labs via USPS Overnight. Hopefully this will make a difference so that he has a last set of DNA sequences for his thesis that will make a better story.

A new issue of Southeastern Naturalist just came out. It has an interesting article by Anna George et al., "The Population Genetics of the Blue Shiner, Cyprinella caerulea". The blue shiner is a federally listed Threatened species found in parts of the upper Coosa River system in AL, GA and TN. Looking at the mitochondrial ND gene they found that the remaining populations of blue shiner are genetically distinct, not to the point of being different species but enough to show a history of isolation. This is what I think we'll find with stippled studfish once we get our DNA samples sequenced. Anyway, this article is in Vol. 7, No. 4, pp. 637-650 of Southeastern Naturalist.

Friday, December 19, 2008

11-KT Effects On Scarlet Shiners, The Graph

I had a chance today (after a slew of other business) to graph the length/weight data from the 11-KT experiment with the scarlet shiners. Interestingly, the lower 11-KT treatment of 15 ng/38 liters produced the largest fish after 6 months, with the higher treatment of 35 ng/38 liters producing the second largest group, and the control fish in third place. The three largest individuals from this experiment were all in the 35 ng treatment, and all are obviously male. I'm not sure if this is a real effect or merely an artifact of small sample size. Anyway, the graph of this is below, definitely click on it to view it at larger size.

Wednesday, December 17, 2008

Preliminary Measurements Of The 11-KT Scarlet Shiners

I measured the standard length and weighed all of the scarlet shiners from the 11-KT experiment. There is no apparent pattern in length; the averages for all three groups, high, lower and control, are about 42 mm. The weights are possibly interesting, though. The highest average weight is the high 11-KT group, followed in order by the lower 11-KT and control groups. This might be a believable effect, since androgens like 11-KT stimulate muscle bulk among other things. But with such a small sample size I'm not certain of this, merely intrigued. I'm leaving brain dissections until the students come back in early January since I think they're better at it for now than I am(!), and we have little margin for error by doing bad dissections.

Wednesday, December 10, 2008

I Just Sacrificed The 11-KT Scarlet Shiners

Yeah, today's the day. I stopped the grow-out experiment I started on May 30 with three treatments of young-of-the-year scarlet shiners: one group exposed to 35 ng of 11-ketotestosterone in 38 liters of water, one group exposed to 15 ng of 11-KT in 38 liters of water and one control group (no exposure to 11-KT). The experiment started with 8 or 9 individuals in each treatment, in two separate aquariums for each treatment. Today I ended up with 3 individuals in the 35 ng treatment, 5 in the 15 ng treatment, and 3 controls. It's not a statistically powerful test, but I hope it's an informative pilot project. It seems that individuals from the two 11-KT treatments grew bigger (I haven't measured them yet). What we're really interested in is whether there will be differences in brain size, and in the size of specific brain regions. In principle the ones exposed to 11-KT should be more "male"-like, which means larger size, more vivid color and a larger brain. We'll see...

Monday, December 08, 2008

The Redline Darters Are Looking Good

The two redline darters we brought back from Estill Fork on Friday seem to be well-adjusted in my 20-gal high tank in the lab. I'd guess that they're from the 2007 year class, since they're not quite full size like some individuals we've found in Hurricane Creek. But they are well-colored. One of them is definitely male, with deep brooding colors and striping around his head and pointed snout that almost looks like a Japanese cartoon character. The other is probably female, although I'm still not fully convinced that it's not a male. I've never kept this species before, but they seem to complement the black darters. The redlines behave more like marine gobies, almost hopping around the sand and propping themselves up on their large pectoral fins while looking around expectantly. The blacks are more prone to short bursts of swimming around the bottom and even chasing food up into the water column. So I'm happy with it, at once a cheap entertainment and natural history education.

Friday, December 05, 2008

I'm Happy, We Had A Good Day At Estill Fork

It was a cold day today, maybe not even 40 deg. F, but our trip to Estill Fork went well. Andrew, Brittany and James went, and everybody had waders. Andrew's weren't insulated but at least he stayed dry. I found that the waders I've been using now have a small leak in the left boot, just enough to be annoying after 2 hours when your sock is wet. But I think I can fix it.

Anyway, the water temperature had dropped to 6 deg. C, but we all noticed that the water was very clear today; it was no problem seeing fish in the stream. We started with some seining by the low bridge, and actually caught a few telescope shiners this time. This involved dodging the deer carcass that someone had thoughtfully tossed into the pool below the bridge... Below is an image of the stream coming into the bridge, flowing fast, clear and cold out of the mountains to the north.

We went about 300 meters downstream and found a really productive series of riffles and fast flowing pools. Over about an hour we caught ~45 telescope shiners, but only maybe 4 scarlets. And as usual we caught unbelievable numbers of striped shiners. But we also found some interesting darters, not surprisingly, since we were in primo habitat for a number of species: fantails, Tennessees, rainbows, redlines, a stripetail, and the best of all, a blueside with those amazing turquoise rectangles on the side. James took the blueside home for his aquarium, and I kept the two redlines for the scarlet shiner/black darter aquarium in my lab. I think I have a pair. And the good news is that no one fell into the creek, I think I came closest.

Below is a shot of James, Andrew and Brittany processing the fish, putting the shiners in the clove oil solution for euthanasia and the darters we kept into a bait bucket.

And here's a closer view of that set-up, with a few deceased telescope shiners floating on the surface of the clove oil solution. Poking into the bottom of the photo is a beaver stick that James picked up from the water, one of many.

We hope to go back to Estill Fork at the end of January, I don't think it could be much colder. And next week we should finally run the Western blots to measure NMDAR proteins in the brains we prepared last month, at least I hope so!

Thursday, December 04, 2008

We're Getting DNA Sequenced At McLab; No, Really!

Kris just left with a box to ship 8 samples of purified PCR product killifish cyt-b mtDNA to a DNA sequencing business in San Diego commonly referred to as McLab. It turns out that the company is really "Molecular Cloning Laboratory", but of course that gets shortened to McLab by everyone but the company itself. So anyway, if this works, Kris will have the last 4 sequences he needs for his mummichog project, those that are from Nantucket (which is the whole point of the project, to compare Nantucket fish to those from the mainland to see if there's any evidence of differentiation in the isolated population). Also in the box are four cyt-b samples from stippled studfish as a test. If it goes well, we have another 30-something to ship out and hopefully get a good idea of what degree of genetic diversity exists within the species, and between it and several related species. I'm about ready to do something radical and weird like praying for good results(!).

Tomorrow we're going back to Estill Fork to see if we can find where the scarlet and telescope shiners are hiding. Sometimes I think we should start a striped shiner project just because we can always find bunches of them. Tomorrow should be a cold, dank day, but sunny. We've had a cold rain last night and into the morning, but it seems to have stopped.

And if you're flunking one of my classes, please don't ask me to change your grade just because you have personal problems or whatever. I guess I'm a conservative in my old age, just come to the damn class, read the assignments, and show up awake for the exams. Otherwise, it's "thanks for playing!".