Adam's Work

With the baby coming soon I figured I'd give an update about the work I really do and then step out of the spotlight for baby :) So last year I completed 4 rotations through various labs here at the U working on different projects that relate to bacteria. At the end of last year I decided to join the lab where I did my 3rd rotation. So now I officially work in Dr. Colin Dale's lab studying the evolution of symbiosis between bacteria and insects. Endosymbiosis is simply put two organisms living together (One inside of the other). Think of it where the insect is a living fishbowl and the bacteria are lots of tiny fish that live inside of it. This might seem like a bad idea for the insect to be loaded with bacteria, but ironically (in many cases) the bacteria are critical to the insect's survival. (Did you know?: The same is true of us? In fact the number of bacterial cells inside of each of us outnumber our own cells ~10 to 1. The reason this is possible is because bacterial cells are so much smaller than our own).

Now that you understand what symbiosis is, I can explain what I study. Inside of the Tsetse fly (not a house fly) there is a parasitic protist called a Trypanosome that is pathogenic to humans; it causes African Sleeping Sickness. (Hey, you said you worked on bacteria!)...Also living in these flies is a bacteria named Sodalis glossinidius. Cool name right? Well this bacteria has a cool genome (Genome = all the genes in an organism, Gene = a region of DNA that gives the organism a specific ability). So back to the cool genome. Most free-living bacteria have around 4,000 genes give or take (most E. coli have around 4,300), and of those 4,000 genes anywhere from 10-50 of them are pseudogenes (pseudogene = dead gene, or a lost ability).

Now, the bacteria mentioned before Sodalis glossinidius has just over 3,900 genes total. Of those genes present over 1,500 of them are dead (That's almost half!) Now, how do you tell if a gene is dead? Mostly by comparing other bacteria that have the same gene. To keep with the object lesson approach (thanks to Jessica), imagine you are a bacteria and you have a gene that gives you the ability to make pizza. You are happy making your own pizza and eating it too while you live on your own in the big world. Now imagine you are picked up and dropped into a pizza factory. Are you going to keep making your own pizza? No way! It's hard work making your own pizza. So in evolution you would say that your pizza gene is now under "relaxed selection." (The opposite of relaxed selection is called "purifying selection," in case you were wondering.) So, the same thing happens when a free-living bacteria is picked up from the environment and goes into an insect. A lot of the genes it had to maintain it doesn't need to use anymore because it lives on the insect instead. Phew! Take a breath...

So I mentioned before that the way you can tell if a gene is dead or not is to compare your version of the gene with other bacteria's versions of the same gene. This works in many cases but a lot of it is still guess work. What you really need is a directly related ancestor of your bacteria that way you can say with certainty what a gene used to look like vs. what it currently looks like. In other words, if you look at great grandpa's pizza making gene and compare it with your version of the pizza making gene you can tell what parts of the gene have changed over time. The problem now is finding that ancestor because in reality great grandpa is gone and you can't find anything to compare anymore. Without saying too much more, we actually received one of Sodalis' ancestors, well an extant progenitor that is (extant = still living). When we publish our findings I'll tell you more.