Don't Shake the Flask

Because you don't know if it'll explode

The Mitochondria Eaters

IricES1 inside a mitochondrionFrom an aesthetic level, I find ticks themselves to be rather repulsive. But if you look inside this gruesome little insect–oh, how things get fascinatingly bizarre! In a way, a tick’s hidden secret is even more horrible than mere blood-sucking. I’m talking about a carnivorous microbe that devours a eukaryotic cell’s powerhouses: the mitochondria eater.

On the lookout for intracellular pathogens such as Rickettsia bacteria during the 1970s, David Lewis examined a species of ticks, Ixodes ricinus, found in England under electron microscopy. He certainly found some bacteria, but they were doing something really weird–they invaded only mitochondria and not other organelles of the cell.

Nowadays, there’s still not that much known about this mysterious bacterium–it still doesn’t even have a proper name. (Scientists are still calling it IricES1 for Ixodes ricinus endosymbiont.) What is known is that IricES1 belongs to a group of bacteria called alpha-proteobacteria and its niche is restricted to the eggs of the female tick. A bacterium will invade the mitochondria of the egg and eventually consume the entire mitochondrion matrix until there is nothing but “a swollen empty sac containing a rich population of bacteria.” Luckily for the tick, the egg itself seems unharmed and when fertilized, will develop into a seemingly healthy tick.

But with this predatory/symbiotic relationship restricted to the female germline, one can’t help but draw parallels between this and other sex related symbiotic relationships such as Wolbachia and its myriad invertebrate hosts. But can this be something totally different or is this just one stage in the process of a bacterium becoming inexorably linked to its host?


I was outside for a little while this afternoon and things looked like autumn with the bare branches and the slightly browning leaves. The sky overhead was scattered with small white clouds and heavy gray-blue clouds occasionally spitting droplets. Other pedestrians were craning their necks up to look at the hodge-podge clouds, heedless of the stiff breeze blowing hair over their eyes.

I saw a particularly ominous cloud loom over a line of European pines (I know they’re European because I overheard an old, blubbering biologist say with a bit of regret that nobody ever bothered to plant the native species) and I was suddenly struck with a fierce pang of longing for something that might never be.

I wanted to lie on the steep grassy knoll beside those pine trees and to just watch the clouds racing by. I’d stay there, even if it started raining in earnest. But I ended up hurrying back inside to do those bits of necessary things and spending five minutes typing this out so I don’t forget.

The Thursday Threesome: Full Moon Rising

Onesome: Full– Full? What meal fills you up the most during your day, breakfast, lunch or dinner? …or is it the ice cream you’re digging into as you wander around the blog world long past when you should be asleep?

Not one in particular.

Twosome: Moon– Do you really think there’s any truth to the popular idea that “things” happen when the moon is full? Come on, it’s just us here…

No, it’s just superstition.

Threesome: Rising– …and shining? : What is your normal wakeup time on Thursday mornings? …and can you be described as a “Morning Person” or not?

It depends. Considering my short answers today, not really.