Newly Found Organism Reveals History Of Genes, Named After Razorbacks

Sep 17, 2013

A uniflagellate pygsuia.
A uniflagellate pygsuia.
Credit Mathew Brown

Researchers from the University of Arkansas have discovered an organism they say shows a genetic link between single celled organisms and multicellular animals and fungi. What's more, they've given the organism a name that would make many Arkansas sports fans proud.

Pygsuia biforma (pig-SOOIE-ah bye-FOR-ma) is a type of protist, or eukaryotic microorganism—a single-celled organism that shares characteristics with animals, fungi and plants. Matthew Brown is now associate professor of biology at Mississippi State University. He completed his undergraduate and graduate work at the U of A in Fayetteville, where research on the organism first began.

In Fayetteville he worked with Jeffrey Silberman of the Biology Department who discovered the organism through a culture at his lab.

Silberman sent the samples to Brown who helped determine Pigsuia Biforma's genomic sequencing while doing post-graduate research at Dalhousie University in Nova Scotia. While there, Brown and his team used super computers to sequence the organism's genome from samples he received from Silberman. This was a process, Brown says, that involved sorting through massive amounts of data and took several months.

But what's important about this discovery, Brown says, is that in the Pygsuia biforma, he discovered genes mainly associated with animals and fungi, pointing out that the discovery sheds light on the developmental origins of those genes. He says this demonstrates that many of the genes found in multi-cellular organisms have their origin in single celled organisms, suggesting that genes develop further back on the evolutionary tree of life than is commonly believed.

“So if you imagine animals are just a leaf on the tree and if you go back further, back to where the stems are or the branches are: that's where we're actually able to place genes that are associated with multicelullarity, in organisms that are actually unicellular,” says Brown.

He says his findings show that certain genes prominent in animals and fungi can exist in other, simpler organisms.

Discovering organisms and placing them on the evolutionary tree of life makes up a large part of Jeffrey Silberman's research as well. Silberman says the discovery of Pigsuia biforma first came about from his regular practice of collecting soil samples from a cove near his mother's house in Cape Cod, Massachusetts. He often brings those samples back to his lab in Fayetteville to see what he can find.

“I start cultures from these sediment samples from my mom's house and all sorts of different organisms come up. And most of the organisms I can't get into stable cultures but a lot of the organisms I can. So I've discovered a lot of new-to-science organisms just from my mom's house,” says Silberman.

“It's a gold mine,” he says. “A gold mine for new organisms.”

As a native of Harrison, Brown says he chose the name Pygsuia to partly acknowledge his Arkansas roots; given how in some ways, the organism may resemble a razorback when examined under a microscope.

A biflagellate pygsuia (left) and a uniflagellate pygsuia (right)
A biflagellate pygsuia (left) and a uniflagellate pygsuia (right)
Credit Mathew Brown

“The end of the pear shape [of the cell] sort of looks like a snout,” he says. “And then the body itself is quite round. Then on one side of the cell are these little spikes which are actually phylosudopods, which are actually used as locomotion for this organism. And they move in this conveyor belt like fashion. But the spikes are very sharp and they're only on one side, so they kind of look like the dorsal bristles of a little razorback.”

Brown notes that the “Pyg” derives from the mythical creatures known as pygmies. And “sui” derives from suid, a scientific name for pig (“a” was added to latinize the name). Biforma, refers to the two forms of the Pygsuia. One appears to have only one flagellum (a squiggly physical feature that affects the organism's locomotion) and another appears to have two flagella.

The findings were published in the British biological journal, Proceedings of the Royal Society, B.