New genetic 'operating system' facilitated evolution of 'bilateral' animals

The evolution of worms, insects, vertebrates and other "bilateral" animals—those with distinct left and right sides—from less complex creatures like jellyfish and sea anemones with "radial" symmetry may have been facilitated by the emergence of a completely new "operating system" for controlling genetic instructions in the cell.

That's the hypothesis of molecular biologists at UC San Diego. They report in the October 1 issue of the journal Genes & Development that this new system of controlling gene networks, analogous to a new computer , paved the way for new animal body plans, just as different operating systems allow the development of new kinds of computer apps.

One key player in this theory is an ancient protein termed "TATA box-binding protein," or TBP, which is found in organisms ranging from archaebacteria to humans. A billion years ago, TBP served as the core of a single "operating system" for gene expression.

The UC San Diego scientists focused their attention on a more recent protein related to TBP termed "TBP-related protein 2," or TRF2. They found that TRF2 is present in bilateral animals, and is absent in animals that lack bilateral symmetry, such as jellyfish, sea anemones and sponges. This observation inspired the idea that the emergence of TRF2 provided animals with an entirely new operating system with new gene expression programs ("apps") that facilitated the evolution of bilateral organisms.

While their hypothesis initially seemed far-fetched, the UC San Diego scientists continued to analyze TRF2 in greater detail. They found that the new facts were like interlocking pieces of a jigsaw puzzle that fit together into a coherent picture. For example, bilateral animals have three germ layers—ectoderm, mesoderm and endoderm—in the embryo, whereas more primitive radial animals, such as and , possess only two germ layers—an ectoderm and endoderm.

"It turns out that TRF2 appears to be important for the formation of the mesoderm, the germ layer that is missing in radial organisms and is present in bilateral organisms," said Jim Kadonaga, a biology professor at UC San Diego who headed the study "In this manner, the pieces of this scientific jigsaw puzzle fell into place."

"The emergence of TRF2 essentially doubled the regulatory capacity of the organisms because TBP and TRF2 can function mostly independently of each other," he explained.

The scientists began studying TRF2 while conducting research on a related project, which they published this past June in Genes & Development. In that study, they reported the discovery that TRF2 plays a key role in the production of the 80 proteins that make up the ribosome—the protein factory of the cell.

"Those findings revealed that TRF2 can support the transcription of a specific network of genes independently of TBP, and suggested the existence of two operating systems based on TBP or TRF2," said Kadonaga.

Sascha Duttke, a graduate student in Kadonaga's laboratory trained in evolutionary biology, was curious as to how and why this second system of transcription evolved. So he examined the presence or absence of TRF2 among different animal groups with the help of Russell Doolittle, one of the world's experts on protein evolution and an emeritus professor of biology and chemistry at UC San Diego. This led to the finding that TRF2 is in bilaterians but not non-bilaterian animals.

"In our current model, there was originally only a single TBP-based operating system, and then the emergence of the new TRF2-based operating system led to new gene networks ('apps') that facilitated the emergence of bilateria," said Kadonaga. "These new included those that are involved in the development of the body plan and the mesoderm. We postulate that the new TRF2-based networks provided the extra diversity of regulatory function that led to the evolution of more complex organisms—specifically the bilateria, which constitute about 99 percent of living animals."

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Journal information: Genes & Development

Citation: New genetic 'operating system' facilitated evolution of 'bilateral' animals (2014, September 30) retrieved 25 May 2019 from
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Sep 30, 2014
Before you post a comment on this article stop and think.

On all previous occasions you've stuck your fingers in your ears, stomped your feet and shouted, No! No! No!

Be honest and admit it is your fundamentalist religious beliefs, not science that guide your views.

Sep 30, 2014
Damn, you hit submit before I did.

Okay verkle, how do you account for the fossil record, the extinction and raise of new species?

Without evolution all you have is your Bible, admit it.

Sep 30, 2014
they have to concocting up more and more "magic". "Somehow, this happened this way..."
that is how your religion works... not science.
Science requires proof... empirical evidence as well as repeatable experiments.

proof that you don't know about science: http://www.talkor...comdesc/

Evolution is real
your religion is just trying to control you so that it has a good little automaton

Sep 30, 2014
@Verkle - why do you bother posting here at all? Your dogmatic posts demonstrate your lack of interest and willingness to learn and grow. You don't seem at all happy here so why not go do something you actually enjoy.

Sep 30, 2014
Verkle, the evolution of multicellular animals makes perfect sense,
The first multi cellular animals were sea sponges, no symmetry
Then fractal organisms like charnia
Then the radially symmetrical Cnidarians, like jelly fish and sea anemones
Then bilateral things like arthropods and animals with vertebrae

It's just so natural it is easily intuitive once you know about it.
We even have creatures in between those examples, such as Siphonophores and Dickinsonia

Oct 01, 2014
@OZGuy: As I remember it, someone hypothesized that since there are pay-for-spam businesses, verkle is on hire to 'promote' cretinism. Of course, that his/her infantile 5-year old tantrums tar it is beyond the grasp of those who pays, which ultimately is some sect/woo organisation. The cretinist JVK may be something similar, since it promote a woo drug site.

And then we have the no-relativity/electric-universe anti-scientists... Oy! But also a lot of laughs, if you put aside the concerns for science and society for a while. We will always have to live with sociopaths in a free society. Unless someone comes up with drugs with benefits that fixes their problems.

Oct 01, 2014
My wife's an AP Biology teacher, and noted that echinoderms and quite a few other 'radial symmetry' organisms have mesoderms. Do they have TRF2, as well? Or was the summary author (or original article authors) mistaken in their reference to mesoderm pervasiveness?

Oct 01, 2014
De Novo Origination of a New Protein-Coding Gene in Saccharomyces cerevisiae

Q: How do evolutionary theorists get from de novo creation of a gene in a microbe to evolution via "TATA box-binding protein" in organisms from archaebacteria to humans?

A: "[W]hat Haldane, Fisher, Sewell Wright, Hardy, Weinberg et al. did was invent.... The anglophone tradition was taught. I was taught, and so were my contemporaries, and so were the younger scientists. Evolution was defined as "changes in gene frequencies in natural populations." The accumulation of genetic mutations was touted to be enough to change one species to another.... No, it wasn't dishonesty. I think it was wish fulfillment and social momentum. Assumptions, made but not verified, were taught as fact."


They just keep making stuff up, don't they?

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