The Photosynthetic Sea Slugs, and Horizontal Gene Transfer

The sea slugs known as Elysia chlorotica are certainly a strong contender for my favourite animal.  They are born clear, and they feed on algae for nutrients and energy.  But, they poke little holes in the turgid algae pieces with their tooth, and suck out the individual chloroplasts.  The chloroplasts do not get digested, and instead migrate to the animal’s skin, where the animal has gained the ability to keep the chloroplasts alive inside its animal cells (not in-between, but inside).  The chloroplasts then photosynthesize using sunlight, and produce energy for the slug’s cells.  The chloroplasts make the slug’s skin green, and indeed the slug has evolved to take on a shape which maximizes surface area, in order to harvest as much sunlight as possible.  The adults resemble leaves for this reason!

Watch this video of the little guy sucking out the chloroplasts from a piece of algae:

These slugs were successfully kept alive in excess of a year in a tank with absolutely no caloric input in the water, and with nothing but a UV “grow lamp.”  Their growth was very slow during this time, but this indicates that an animal was capable of living entirely off of photosynthesis!  This is the only animal known to be capable of keeping the chloroplast endosymbiont alive. Continue reading “The Photosynthetic Sea Slugs, and Horizontal Gene Transfer”

An Acetone Supernova in the Lab

In an acetone supernova, an acetone supernova in the laaaaab…

Wondering what those splotches are where the ink started running on the first panel? Guess what caused that.

Welp, this is how my day has gone.  Pretty much all week, really.  I thought I had a pretty good grasp on thermodynamics, but using the rotavapor has made me question everything I’ve ever learned.

I understand why, when the vapor really gets going, it warms up the “cone of cold” and causes an eruption of dry ice and acetone.

I understand why the distillate spontaneously freezes every now and again.

But there seems to be no rhyme or reason to when the concentrate boils over or not.  I crank the temperature down to 4 degrees C, I dump ice in the water bath, and yet every time it boils out of control for about 30 minutes and then it calms down forever.

At first I thought, well duh, I boiled all the acetonitrile off so now it’s behaving.  But lo, I brought the concentrate down to the “stable state,” turned the machine off to take lunch for an hour, came back, started it up again, and oh boy it just started boiling all over again.  If I ever stop it or take any sort of break during this “stable state,” picking up where I left off means starting back at the beginning.

Thermodynamically, I cannot explain this.  Therefore, I have decided that there’s something wrong with the vacuum pump which means it needs to warm up for a half an hour before it pulls a stable vacuum in the flask.  I tried to test this, but then I realized I had to turn the pump off to pour my liquid into the flask and restart it… but I will find a way to test this hypothesis! Mark my words!

ARB Comics!

This is an almost completely true account of me using ARB today.

Using ARB can be dangerous.

Apart from discovering the button that kills people in ARB, today was the first day that I thought about the absurdity of using 3 different alignment programs to get my work done:

  • I use SeaView to align my sequences and to view already-aligned sequences.
  • I use Clustal primarily for its “range information” function, to trim my sequences at my conserved trim targets.
  • I use ARB to import the alignments and make phylogenetic trees.

Perhaps one day, there will be one aligner program that does everything I need it to.  Do you hear me, you bioinformaticists out there??