Today I got the results back from testing my blood for Rickettsial antigens and while looking up the species of Rickettsia my blood was tested against I discovered a very interesting fact which totally blew my lab-mate and my mind.
R. prowazekii is the closest free-living relative of mitochondria.
Let me translate... The statement above is saying that an ancestral strain of a current species of parasite called Rickettsia prowazekii is the closest common ancestor of mitochondria. This ancestral species was a Rickettsia-like intracellular symbiont, meaning it relied on its relationship with another organism (in this case another cell) to live. The term "free-living" is a little misleading, as R. prowazekii cannot live outside of a host or vector, but, R. prowazekii is "free-living" in the fact that it is no longer intracellular, as its closest common ancestor to mitochondria was.
As scientists studying DNA we learn a lot about mitochondria (circular DNA within eukaryotic cells responsible, in most part, for energy production). We are taught that the most likely origin of mitochondria was when one single-celled organism engulfed another creating an endosymbiont (cell living within a cell). There are multiple theories about the engulfing versus the engulfed cells but the typical explanation is an anaerobic (can live without oxygen) bacteria was engulfed by a nucleus-bearing cell. This cell-in-a-cell combo evolved to be able to create its own energy and later developed the capability to become multicellular organisms.
So, this ancestral species evolved into both mitochondria and R. prowazekii: mitochondria when it became fully incorporated into the other cell (mutual symbiosis) and R. prowazekii when it became a parasite (non-mutual symbiosis). In all of the times we have been taught about the origins of mitochondria, it was never mentioned that the common ancestor isn't just any bacteria but the common ancestor of a parasite. It puts a whole new dynamic on the origin story and the evolution of symbiotic relationships as well.
The original statement was found on Wikipedia but was verified by this scientific publication:
And, yes, that is the same Ted Turner that owns all the bison!
*Thank you David Forgacs for sharing this video with me in the first place. Goooood mule ;)
This week I had an unfortunate run-in with an old enemy… back pain! Having degenerative disc disease, I always have a lingering level of lower back pain but this had the added fun of sciatica pain down my leg as well as pain in my arm. This was all spurred from tweaking my back while gardening last Sunday and gradually got worse as the week went by. I am also still recovering from my post-Africa injury. My toe still remains wrapped from my run in with an evil escalator at the Atlanta airport 30 minutes after getting off a 17 hour flight. The limping was probably adding fuel to the back pain fire. I woke up on Friday morning in so much pain I resorted to going to a doctor since I had exhausted all of my typical flair-up remedies (heat & ice, yoga, ibuprofen and the chiropractor was closed until Monday for Easter). Some steroids and muscle relaxers later, I am able to move but not quite like a normal human being yet.
One thing I noticed with my more crippled than normal demeanor was the amount of other graduate students who could sympathize with my back pain. The school year is almost over so, at least for me, stress levels are rising with trying to be on top of coursework, making sure I have a solid game plan for my research over the summer, and financially freaking out as I watch my savings dwindle away before my eyes on boring everyday life stuff and not the fun stuff I want to be spending it on. Sitting in a chair staring at a computer screen for hours on end isn’t the best for one’s back either. Basically, we all feel like old people moaning and groaning as we stand up from our chairs or bend over to pick something up.
I may not be one to be preaching since I am currently heavily medicated for back pain but here are some suggestions (which I obviously didn’t follow myself) for keeping your back healthy during all the craziness:
● Take a break... Get up from that computer desk every so often and stretch.
Also, today, another one gets a little more dirty... HAPPY 30th BIRTHDAY MEGAN!!!!
Happy 80th Birthday Jane Goodall!
I am a biologist and my life is crap!