The human genome contains genes donated by microbes

Bacillus  cereus

It was the first fialure of the human genome, or so I thought. When presented the   Book of Life   turn of the century, one of the most shocking data was the presence of dozens of genes between bacterial interspersed   properly   humans, but the burning lasted very little, and the conclusion was attributed to an error. It was not. Fifteen years after that heated debate, an analysis that benefits from the major recent advances in genomics proves beyond all doubt that our DNA contains 145 genes of microbial origin. And they are important.

The work of Alastair Crisp and colleagues   University of Cambridge   is not limited to human DNA, but examines the genomes of other species of primates 9, 12 and four worm flies, and a partial analysis of 14 other vertebrates. This broad perspective along the trend shows that the donation   of genes from other species (horizontal transfer, in the jargon) is common in animals, and resulting in tens or hundreds of genes of microbial origin as active in a species. The results are presented in   Genome Biology .

In our species, researchers have confirmed 17 genes that were already suspicious of foreign origin, and have identified additional 128. One is the ABO blood group gene responsible

Imported genes of bacteria and other microbes covering functions not seem   chosen   random: most are related to metabolism, kitchen room   Cell, or set of chemical reactions that manage their energy flows and regeneration of its components. The heart of metabolism is constant universal-and biology-, but the adaptation of species to their local environment often requires new skills to manage metabolic chemical peculiarities of the environment: that's where the imported genes of bacteria may be crucial .

In our species, researchers have confirmed 17 genes that were already suspicious of foreign origin, and have identified additional 128. One is the gene responsible for ABO blood group.Others are mostly related to the metabolism of fats and amino acids, immune response, inflammation and antioxidant activities of the cell. As much of our interaction with the microbial world is is based on acquired genes from microbes themselves.

None of these genes is a recent acquisition: gene transfer occurred before the human species evolved, and many of them before the appearance of primates, along the tortuous evolutionary history of vertebrates. But that itself is an indication of its importance, since they have been around for tens of millions of years.

The donation of genes between species, or horizontal transfer, is anything but a surprise in the microbial world. Bacteria genes so effectively that, according to recent estimates, over 80% of bacterial genes have been implicated in some point of evolution in an exchange between species are exchanged. This mechanism explains, among other things, the ease with which bacteria acquire resistance to antibiotics and the risk of microbial strains harmless become virulent overnight.

Gene transfer occurred before the human species evolved, and many of them before the appearance of primates

It is in the animal world where the horizontal transfer was hitherto controversial except in very special cases. For example, are known to have acquired genes nematode worms and bacteria to plants and some bacterial genes imported beetles now allow them digest coffee seeds. There are also bugs family Apidae they have imported genes for carotenoid synthesis (dyes tomato and carrot) that confers a useful orange tint in their environment.

"This is the first study to show the extent to which horizontal gene transfer occurs in animals, including humans, leading to hundreds of active genes outsiders" explains first author of the work, Alastair Crisp, Cambridge. "Surprisingly, far from being a rare phenomenon, it appears that gene transfer has contributed to the evolution of many animals, perhaps all of them, which means we have to rethink the way we think about evolution."

The   Donors   gene are not only bacteria but also protists (unicellular eukaryotic organisms, that is, made ​​of the same cell type constitutes the body) and virus. The latter are particularly important in the evolution of our lineage, the primates. There are also some genes from fungi, which are the main reason for the original controversy: it was thought that was dropped their origin by horizontal transmission, if only he had discarded its bacterial origin.

We are used to seeing bacteria as the enemy to beat. But they are also part of our deeper logic.

 With a Licence   Creative Commons 4 International

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