On a listserve which shall remain nameless a botanist yesterday was casting about for a good representative of a colonial protozoan. Having read up on the model organism Dictyostelium discoideum (common name “social amoeba”) a couple years ago and blogging on it then I immediately suggested it and described why it is a model for protozoan to metazoan evolution and also described its interesting display of altruism:
“a good colonial protozoan”
A model organism for metazoan evolution: the social amoeba.
Fascinating critter and recently completely sequenced (see link below). It’s also a model for altruism. When times get tough the tough social amoebas get together under a chemical call to arms where a million of the usually independent animals gather together to form a slug which raises a stiff shaft out of the soil into the air upon which form spores. After the spores are released they separate and go about their business as independent animals again. Except for those comrades whose bodies formed the stiff shaft. They die. At the time of formation none know which will be sacrificed but in the end… “The needs of the many outweigh the needs of the few. Or the one.” -Lt. Commander Spock
Biologists Determine Genetic Blueprint Of Social Amoeba
I always like to include an interesting link on the subject matter and I googled up the one above without really doing more than skimming it. That the social amoeba had been completely sequenced was news to me yesterday even though it was completed 18 months ago (I REALLY need to bite the bullet and buy a subscription to NATURE). When my own listserve article bounced back to my mailbox I clicked on the link again and read the whole article.
Low and behold I stumbled onto this gem of a quote in the Science Daily article:
Ã¢â‚¬Å“It is more closely related to fungi and animals than we had previously thought,Ã¢â‚¬Â says Adam Kuspa, a professor of biochemistry and molecular biology at Baylor College of Medicine in Houston and a senior author of the Nature paper.
The discovery will also improve geneticistsÃ¢â‚¬â„¢ understanding of how the genes from Dictyostelium and other genetic model organisms have been conserved or adapted through evolution in humans and other organisms.
Ã¢â‚¬Å“The cells which gave rise to plants and animals had more types of genes available to them than are presently found in either plants or animals,Ã¢â‚¬Â explains William Loomis, a professor of biology at UCSD and one of the key members of the international sequencing effort. Ã¢â‚¬Å“Specialization appears to lead to loss of genes as well as the modification of copies of old genes. As each new genome is sequenced, we learn more about the history and physiology of the progenitors and gain insight into the function of human genes.Ã¢â‚¬Â
“The cells which gave rise to plants and animals had more types of genes available to them than are presently found in either plants or animals” -William Loomis
More genes available to single celled predecessors of metazoan animals and plants?! This was a testable prediction of the front loading hypothesis I made a couple years ago on Panda’s Thumb, although I was more interested in the genome of amoeba dubia because of the size of its genome which is some 200 times the size of the human genome by weight of DNA in the cell.
Can you spell “front loading”? I knew you could. Nothing in organic evolution makes sense except in the light of front loading. 🙂