Genes: Surprisingly similar across species

TORONTO, April 16 (UPI) -- Canadian-led scientists say they've discovered surprising genetic similarities among chickens, frogs, pufferfish, mice and humans.

The researchers, led by University of Toronto Professor Timothy Hughes, said their findings show expression in tissues with a limited number of specialized cell types is strongly conserved, even between mammalian and non-mammalian vertebrates.

The scientists, investigating evolutionary alterations in gene regulation, studied 3,074 genes present as a single unambiguous copy in each of the five genomes.

Hughes said the study found clearly strong evolutionary constraints on tissue-specific gene expression, suggesting the existence of a basic ancestral pattern of expression in each tissue.

The strongest similarities were seen in brain tissue.

"This relatively low divergence of gene expression in (the) brain supports the hypothesis that neurons participate in more functional interactions than cells in other tissues -- imposing constraints on the degree of alteration that can be tolerated," he said.

Hughes said genes expressed in tissues subject to greater environmental influence, such as intestine, stomach and spleen, might be more likely to take on new roles and diverge in expression as a means of adaptation.

The study appears in the Journal of Biology.