University of Richmond

University of Richmond Scientists Discover Sophisticated Gene in Sponges

August 19, 2005

When University of Richmond biology professors April and Malcolm Hill started doing research on sponges a decade or so ago, they often got blank stares.

Thats no longer the case. Theres been an explosion of interest in sponges over the past 1015 years, Malcolm Hill, an evolutionary ecologist, says. The Hills are at the forefront of that interest, and their research has shed new light on the genes of sponges.

Sponges are among the most primitive animals, and studying them gives scientists a chance to look backward in terms of evolution, says April Hill, a developmental geneticist.

Though sponges are primitive creatures that strongly resemble the earliest animals to appear on the planet, the Hills research has shown they nevertheless carry sophisticated genes that in other creatures control the growth of eyes, the brain and the central nervous system.

Its as if sponges have all these tools, a black box of genes, but still have very simple bodies, says Malcolm Hill.

Sponges have eye, brain and nervous system genes, but they dont use them to make eyes, brains or a nervous system, the Hills studies show.

Sponges lack nerve cells, so they cant produce the complex sensory organs of other animals. Nonetheless, sponges contain genes very much like those that play a role in the development of human sensory systems.

Theres not a whole heck of a lot of difference between sponge genes and human genes, says April Hill. And we share 75 percent of their genetic history, says Malcolm Hill.

The husband-and-wife research team is willing to go so far as to say, with tongues firmly in cheek, that if sponges did make full use of the genes they carry, they might really resemble the popular cartoon character Sponge Bob, Square Pants (minus the pants, of course).

As it turns out, sponges have the genetic potential that could lead to things like eyes, legs and arms, says April Hill.

The Hills refer to their specialty as biological archaeology, and say that by studying sponges, they obtain insight about the earliest stages of genetic evolution in animals.

The evidence is pretty strong that the common ancestor of all animals was very sponge-like, Malcolm Hill says. We can learn a lot about the history of the origins of animals by studying the most primitive ones.

In one set of experiments, described in the most recent issue of Development Genes and Evolution, the Hills identified and isolated a gene from sponges (the Bar/Bsh gene) that in more advanced animals plays a key role in brain and nervous system development.

In ongoing research, they are examining genes (Pax genes) that are involved in eye development in more complex animals. It appears that these sponge Pax genes can produce eyes in other animals without performing that role in the sponge itself.

The two scientists credit the cartoon character with imbuing their research with a cool-factor to their children, along with generating more awareness among the general public that sponges are animals and not plants, even if they dont live in a pineapple, Malcolm Hill says.

Sponge Bobs popularity aside, the two have noticed that sponges are also attracting more attention among scientists. Sponges are important creatures for a number of reasons. They

produce promising anti-cancer drugs, they are the most ancient animal group and provide clues

about our own evolution, and they play important ecological roles in marine systems, according to April Hill.

Most students want to study humans, sharks or dolphins when they come in, Malcolm Hill says, but once they get introduced to sponges, a lot of them come around. Were converting one person at a time to the sponge world.