I’ve covered copy number variations in the past, and the post I put up this morning is kinda along the same lines as the following paper I will introduce. But, in a nutshell, this one is a comparison of copy number variation or CNVs in primate genomes.

CNV is a term used in genomic studies to describe the amount of copies of a particular gene in a particular genotype. Copy number variations are a type of polymorphism that can come about from transposons and restructuring of genomes due to Alu elements. Sometimes changes in CNVs imply that genes have been positively or negatively selected for.

In the new report, soon to be available in Genome Research, the results of a large-scale, genome-wide study to investigate gene copy number differences among ten primate species, including humans have been published. The study, “Gene copy number variation spanning 60 million years of human and primate evolution,” will be online tomorrow and is the most comprehensive research on gene copy number variation across human and non-human primate species so far. It provides an overview of genes and gene families that have undergone major copy number expansions and contractions in different primate lineages spanning approximately 60 million years of evolutionary time.

Dr. James Sikela and team used microarrays with over 24,000 human genes to screen and compare genomic hybridization. In other words, they compared DNA samples from humans to those of nine other primate species: chimpanzee, gorilla, bonobo, orangutan, gibbon, macaque, baboon, marmoset, and lemur in oder to identify specific genes and gene families that, through evolutionary time, have undergone lineage-specific copy number gains and losses.

The authors of the report suggest that,

“many of the genes identified are likely to be important to lineage-specific traits found in humans and in the other primate lineages surveyed.”

Several gene families that exhibited striking lineage-specific differences were highlighted. In particular, the human lineage-specific copy number expansion of a gene called AQP7, a gene that plays a role in transporting water and glycorol across membranes, was pointed out because it could explain why humans have evolved the capacity for endurance running. It may facilitate the mobilization of energy stores during long periods of intense exercise as well as playing a role in dissipating excess heat through sweating. I’ll have more on this tomorrow, when I get access to the paper but the other findings included dramatic gene copy number differences potentially associated with cognition, reproduction, immune function, and susceptibility to genetic disease. Paraphrased from here.

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