Gene Expression Patterns Consistent Among Species

Despite being separated by hundreds of millions of years of evolution, humans and fish apparently still retain the same patterns of gene expression, even if the mechanisms and end results involved have little to nothing in common.

In a new study, conducted by researchers at the University of Toronto, in Canada, and led by expert Timothy Hughes, the evolutionary alterations in gene regulation that five vertebrate species suffered over the eons were closely investigated.

The researchers explain that understanding DNA is one of the most complex tasks in science. Even the simplest action that goes on in the cells is regulated by a vast dictionary of instructions, which makes up the genetic code of a specific organism.

In the new research, it was revealed that the particular, specialized DNA sequences that are used in various species in order to regulate gene expression have changed substantially over the years in the vertebrates that were analyzed.

However, it was also shown that the actual patterns of gene expression was closely conserved in all of these animals. “There are clearly strong evolutionary constraints on tissue-specific gene expression,” Hughes explains.

“Many genes show conserved human/fish expression despite having almost no nonexonic conserved primary sequence,” he goes on to say, quoted by Daily Galaxy.

The study covered a number of 3074 genes, each of which was present in a single copy in each of the five vertebrate genomes. One of the main conclusions of the analysis was that a basic, ancestral gene expression pattern exists. Experts have called it the “inner fish.”

“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,” Hughes explains.

The brains of the five vertebrates showed the most substantial similarities in gene expression, the study showed. This makes evolutionary sense, since it's a lot more likely for expression patterns to change in the intestine, stomach and spleen than th ebrain.

“It is likely that the conservation of gene expression extends beyond the base of vertebrates, co-expression of neuronal genes, for example, has been observed as far as nematodes,” the group says of the implications the new work has.