ScienceDaily (Apr. 16, 2009) — A study of gene expression in chickens, frogs, pufferfish, mice and people has revealed surprising similarities in several key tissues. Researchers have shown that expression in tissues with a limited number of specialized cell types is strongly conserved, even between the mammalian and non-mammalian vertebrates.

Timothy Hughes from the University of Toronto, Canada, worked with a team of researchers to investigate evolutionary alterations in gene regulation in the five different vertebrates. They found that although the specialized DNA sequences that regulate the expression of the genes seem to have changed beyond recognition over the hundreds of millions of years since the clades parted evolutionary company, the actual patterns of gene expression remain closely conserved.

According to Hughes, "There are clearly strong evolutionary constraints on tissue-specific gene expression. Many genes show conserved human/fish expression despite having almost no nonexonic conserved primary sequence."

The authors studied 3074 genes that were present as a single unambiguous copy in each of the five genomes. The similar expression profiles they uncovered suggest the existence of a basic ancestral pattern of expression in each tissue, the so-called 'inner fish'.

The strongest similarities were seen in brain tissue. Hughes said, "This relatively low divergence of gene expression in 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". Genes expressed in tissues subject to greater environmental influence (such as intestine, stomach and spleen) may be more likely to take on new roles and diverge in expression as a means of adaptation.

Although this study only investigated vertebrates, these expression profiles may go much further back into our past. The authors conclude, "It is likely that the conservation of gene expression extends beyond the base of vertebrates, coexpression of neuronal genes, for example, has been observed as far as nematodes."

Story Source:

Adapted from materials provided by Journal of Biology, via EurekAlert!, a service of AAAS.

Journal Reference:

1. Esther T Chan, Gerald T Quon, Gordon Chua, Tomas Babak, Miles Trochesset, Ralph A Zirngibl, Jane Aubin, Michael Ratcliffe, Andrew Wilde, Michael Brudno, Quaid D Morris and Timothy R Hughes. Conservation of core gene expression in vertebrate tissues. Journal of Biology, 2009; DOI: 10.1186/jbiol130

enlarge

New research shows that the expression of certain specialized genes in vertebrates as different as pufferfish and humans has remained remarkably conserved over evolution. (Credit: iStockphoto/Ernst Daniel Scheffler)

Related Stories

Molecular Map Helps Illuminate Why Mice Only Live For Two Years (Dec. 3, 2007) — Researchers have used gene arrays to identify genes whose activity changes with age in 16 different mouse tissues. The study uses a newly available database called AGEMAP to document the process of ...  > read more

Cancer Researchers Found A New Mechanism Potentially Explaining Evolution Of Signalling Pathways (Feb. 14, 2006) — Cancer researchers at the University of Helsinki, Finland, in trying to find a novel tumor suppressor gene, instead found an important evolutionary change that occurred in a key developmental ...  > read more

Molecular Evolution: Mice Given Bat-Like Forelimbs Through Gene Switch (Jan. 16, 2008) — Scientists have successfully switched the mouse Prx1 gene regulatory element with the Prx1 gene regulatory region from a bat -- and although these two species are separated by millions of years of ...  > read more

Prediction Of Gene Function In Mammals (Dec. 15, 2004) — Gene function in mammals can be quickly and reliably predicted using a high-throughput analysis of patterns of RNA expression, according to an article published in Journal of Biology. This challenges ...  > read more

Search ScienceDaily

A Blue Moon Month