Genome Of Simplest Animal Reveals Ancient Lineage, Confounding Array Of Complex Capabilities
"Trichoplax has had just
as much time to evolve as humans, but because of its morphological simplicity, it is tempting to think of it as a surrogate for an early animal,"....
Earlier mitochondrial DNA studies suggested that this "mother of all metazoans," Trichoplax, was the earliest branch, before sponges diverged, but this remains [/B]debatable—even among collaborators[/B]
"Trichoplax is an ancient lineage—a good representation of the ancestral genome that is shedding light of the kinds of genes, the structures of genes, and even how these genes were arranged on the genome in the common ancestor 600 million years ago," said Srivastava. "It has retained a lot of primitive features relative to other living animals."
Trichoplax has no neurons, but has many genes that are associated with neural function in more complex animals. "It lacks a nervous system, but it still is able to respond to environmental stimuli. "It has genes, such as ion channels and receptors, that we associate with neuronal functions, but no neurons have ever been reported," explained Rokhsar
Of the 11,514 genes identified in the six chromosomes of Trichoplax, 80 percent are shared with cnidarians and bilaterians.
Trichoplax also shares over 80 percent of its introns—the regions within genes that are not translated into proteins—with humans. Even the arrangement of genes is conserved between the Trichoplax and human genomes