November 11, 2008

Gel of the Day: A Horny Little Bug That's Pissing Me Off

Just for the record, I would like it known that the 3-4mm long diaperine beetles lumped together into the species Neomida bicornis are stinky stupid-heads and I don't want to play with them anymore.

What can I say after that deeply professional and scientific appraisal? Well, I can offer up this Gel of the Day as evidence of my contentions:

The first two lanes are 28S and 5.8S nuclear ribosomal subunits and the third is cox1 from Neomida bicornis. The last three are the same genes from a positive control, Bolitotherus cornutus. Everything else is, of course, the same. The same aliquots of primers, the same Taq polymerase, the same dNTPs, the same thermocycler protocol.

Now, if this were the first time I'd gotten a result like this, it would be no problem. And, in fact, it wasn't a problem four attempts ago. This gel is my fifth attempt at getting these sequences! I've tried tweaking everything I can think of with my existing protocol, but nothing changes the result. My next step will be to use a forensic DNA extraction and amplification kit, which I've been trying not to do because of the expense involved.

If not for the fact that I have some evidence that N. bicornis is more than one species, I would have given up on this by now. The thing is, it's worth it to me because part of my research has to do with the evolution of host specificity and I've collected this beetle from four different fungi now. Not only is the coloration different in these populations, but there are more subtle morphological differences as well (for example, the proportions of the tarsomeres of the metatarsi). I've also used the large subunit sequences from two populations — one from Ganoderma lucidum in Florida and one from Pycnoporus cinnibarinus in Massachusetts — in a molecular phylogenetic analysis and guess what... they turn out to fall into two separate clades with 99% bootstrap support in a neighbor-joining tree after 500 replications. In other words, they're taxonomically classified as a single species, but considering how slowly this sequence evolves it's highly unlikely that they really are. I need to get the more rapidly-evolving cox1 sequence to clinch this, along with analyzing a few more populations and I can't get the damned thing.

What a tease.

I mean, just look...

If I had hair, I'd be pulling it out right now. I can take or leave the small subunit, but I must have the cox1 sequence.

OK, that's it, "Neomida bicornis," if that is your real name. You've pushed me too far. Next time you see me on the street, you'd better run. I'm gonna be packing Raid.

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