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The Evolution Of The Monkey Gene That Blocks AIDS
There is a gene in Asian monkeys that could have evolved as protection
against lentiviruses such as HIV, according to an article written by
researchers at Harvard Medical School that is published in the
open-access journal PLoS Pathogens.
The well-characterized gene - TRIM5-CypA - is a hybrid of TRIM5
and CypA, two genes that already exist. The hybrid produces a single
protein that can protect from viral infections such the ones closely
related to HIV. This is not the first time that a TRIM5-CypA gene was
found in monkeys. In 2004, researchers found a hybrid gene called
TRIMCyp in South
American owl monkeys.
It is standard practice among evolutionary biologists to assume that if
similar DNA
sequences are found in the same place in the genomes of more than one
species, then the sequence evolved only once. There is a common
ancestor that first has the gene, and all species that descend from the
ancestor inherit it. However, this does not seem to be the history of
TRIM5-CypA and TRIMCyp.
Researchers did not find the TRIM5-CypA gene in monkeys closely related
to the Asian
macaques, nor did they find it in every macaque monkey that was tested.
Owl monkey TRIMCyp, similarly, could not be detected in any other South
American primate species. The conclusion that the researchers draw
about both genes is that they arose independently - one time for owl
monkeys and one time for macaques. Although there are similar protein
sequences specified by the two TRIM5-CypA genes, there were different
molecular events at the DNA level that are responsible for the
formation of each gene.
According to evolutionary biologists, different species' acquisition of
a similar
adaptation is called "convergent evolution." One example of this is how
birds and bats independently developed flight. The
Harvard team remarks that an unequivocal and striking example of
convergent evolution is seen in the genetic evidence of the two
TRIM5-CypA genes. Researchers believe that it is rare for these kinds
of molecular events to occur that are required to
construct the two TRIM5-CypA genes.
Since the hybridization process occurred at least twice during primate
evolution, the combination of the TRIM5 and CypA genes has given a
strong evolutionary advantage to the individuals who originally carried
the gene. One theory holds that the newly formed genes protected
against infection by prehistoric viruses that are similar to the modern
AIDS virus. If this is true, it could mean that the modern AIDS
epidemic is similar to one that may have beleaguered our primate
ancestors long ago; that is, AIDS is not as unique as we have believed.
Evolution of a TRIM5-CypA Splice Isoform in Old World Monkeys
Newman RM, Hall L, Kirmaier A, Pozzi L-A, Pery E, et al.
PLoS Pathogens 4(2): e1000013. (2008).
doi:10.1371/journal.ppat.1000003
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Here to View Journal Website
Written by: Peter M Crosta
Copyright: Start Sanatate
Not to be reproduced without permission of Start Sanatate
Evoluþia de la maimuþã blocuri de gene care SIDA - The Evolution Of The Monkey Gene That Blocks AIDS - articole medicale engleza - startsanatate