Giant viruses join as another ancestral superkingdom

Mimivirus in amoeba. Credit: Professor Didier Raoult, Rickettsia Laboratory, La Timone, Marseille, France

A study of the proteins of giant viruses adds them to the list of primitive life forms that have existed since the dawn of life.  They seem to constitute a fourth superkingdom. Professor Gustavo Caetano-Anollés led the analysis.

Scientists found ancient structural patterns in the folds of the virus proteins, which are virtually molecular fossils. Folds that are common to all organisms studied are the oldest. Less common folds are, literally, new wrinkles.

The researchers looked at archaea, bacteria, eukaryotes, and both kinds of viruses. The giant viruses have  biochemistry for making proteins, which small viruses have lost.

Modern viruses have lost much of their biochemical machinery and become obligate parasites of an extreme kind.

“Giant Viruses Coexisted With the Cellular Ancestors and Represent a Distinct Supergroup Along With Superkingdoms Archaea, Bacteria and Eukarya“

Research to follow: Oakley Evolution Lab

Todd Oakley at the University of California is unravelling the mysteries of convergent and parallel evolution in a variety of organisms, aided by post-doctoral students on several projects.

“My research involves comparisons of independent evolutionary transitions such as convergence, parallelism, duplication, and homoplasy. Such transitions provide an element of replicability within the singular history of life, and can yield insight into the most general evolutionary questions. For example, when and why do the same molecular or developmental changes underlie similar – though independent – evolutionary changes? What are the fates of duplicated genes, and what causes them to diversify or retain old functions? How can we even determine what is an independent evolutionary event?”

One of his students has discovered that chitons have eye lenses made of aragonite, which is the material used by trilobites.

Evolution 2012 in Ottawa, Ontario

Check out the reaction and link fest at Jeremy Voder’s Denim and Tweed: Evol2012.

All in all, I had a great time, and saw a lot of really cool science. This was the first Evolution meeting I’ve been to where I was never at a loose end—every moment I was in the Convention Centre, I had someone to go see, or a talk to go hear. And, honestly, I finished the meeting without having checked in with everyone I’d have liked to.

Date of first walker pushed back 30 million years

A tiny trackway discovered in sedimentary rock has pushed back the date of the first organism capable of walking to 585 million years ago. This proof is 30 million years older than previously known evidence.It took two years to precisely date the trackway by radiometric dating of igneous rock that intruded into the sedimentary rock. The fossil was found in Uruguay.

The organism was about the size of a grain of rice. A trackway like this shows that it had front and back ends and was bilaterally symmetrical, with limbs that could move it forward. We could call it First Explorer.

See also Study resets date of earliest animal life by 30 million years.

Eucritta–from before the reptile-amphibian split

 

Eucritta melanolimnetes

Eucritta melanolimnetes represents ancestral tetrapods. We mammals did not descend from amphibian: we descended from reptiles. The Amphibians are on a separate branch of the family. Eucritta has features of both. It is a transitional form, vulgarly called a “missing link.” But obviously it’s not missing. Described by Jennifer Clack in 1998, it’s from the early Carboniferous Era.

Clack is having a little joke here: Eucritta presumably means “good creature” and melanolimnetes means “from dark fresh water.”

Eucritta melanolimnetes life reconstruction by Dmitry Bogdanov

The evolution of cholera

Puff the Mutant Dragon explains the history of epidemic cholera, which originated when religious pilgrims spread a relatively harmless germ to new populations, and its evolution into a killer disease: The Making of a Serial Killer.

Transitional forms: muscle proteins

How old is evolution? How conservative? Try this: the proteins that an amoeba (ameba) uses to move are essentially the same as those that make up the muscle fibres in a vertebrate such as ourselves.

Though it appears to have nothing in common with muscular movement, ameboid movement probably depends on contractile components and mechanisms surprisingly similar to those in the muscle cells of animals. …[T]he cytoplasm of an ameba is found to contain thick and thin microfilaments similar in appearance and dimensions to thick (myosin) and thin (actin) microfilaments of striated muscle. Extracts of muscle myosin appear to cross-react with the thin filaments from amebas. And cytoplasm from amebas uses the nucleotide adenosine triposphate (ATP) as an energy source for movement, as muscle does.

From Living Invertebrates, page 27 (chapter on “Protozoans”), by Vicki Pearse, John Pearse, Mildred Buschbaum, & Ralph Buschbaum.

Traces of evolution

I’m reading Animals without Backbones, Volume 2, and every so often I read something that reminds me of our long, long chain of common descent. It’s an old book, about 60 years old, but that means it’s simple and readable. Sure, every so often I mark something to look up in a newer book. But it’s great casual reading.

For example, roundworms, such as earthworms, have developed hemoglobin to help them carry oxygen around their bodies. It’s just floating in their blood: they haven’t developed blood cells. But it’s there. Six hundred million years separate us, but we have hemoglobin, too, slightly different but recognizably a related molecule doing the same job, with random changes in the non-functional parts. Isn’t knowledge wonderful?

You can read more about roundworms here. Or you can read about out last common ancestor (European Molecular Biology Laboratory (2010, February 1). Last ancestor humans shared with worms had sophisticated brain, microRNAs show. ScienceDaily. Retrieved January 21, 2012, from http://www.sciencedaily.com­ /releases/2010/02/100201101905.htm).