14 August 2012

"Selfish" DNA will help to study the aging process

Researchers from Oregon State University, working under the leadership of Professor Dee Denver, for the first time discovered "selfish" mitochondrial DNA in animal cells that damages the body, reducing its chances of survival. The defects caused by this DNA are almost identical to the damage that appears in human cells during aging.

Previously, such unusual DNA was detected only in plant cells. This time the discovery was made by chance – during a genetic study on roundworms Caenorhabditis briggsae.

DNA is a material in which the genetic information of all living organisms is encrypted. The main part of DNA is contained in the nucleus, but certain types of it are part of the energy centers of the cell – mitochondria. Despite a certain isolation, mitochondria work for the benefit of the cell, however, as it turned out, in some cases mitochondrial DNA behave quite inadequately. Such "selfish" DNA replicates faster than normal, does not perform any useful functions for the cell and, moreover, can damage the cell. The presence of such DNA in plant cells negatively affects the flowering process and can lead to sterility.

Initially taken as a laboratory artifact, the "selfish" DNA of nematodes also reduces the number of descendants and reduces the muscle activity of individuals in whose mitochondria it is contained. The existence of such DNA is an evolutionary mystery and indicates the imperfection of natural selection, at least in certain species. Perhaps, in the case of nematodes, this is due to the small size of populations.

It is extremely interesting that the damage caused by "selfish" DNA is almost identical to the results of one of the aspects of human aging – the accumulation of non-functional mitochondrial DNA in cells. In the cells of aging nematodes, there is also an increase in the number of "selfish" DNA.

Experts believe that these unusual DNA are a promising tool for studying the aging process, namely, the causes that lead to mitochondrial disorders.

Article by Katie A. Clark et al. Selfish Little Circles: Transmission Bias and Evolution of Large Deletion-Bearing Mitochondrial DNA in Caenorhabditis briggsae Nematodes is published in the journal PLoS ONE.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru Based on materials from Oregon State University: 'Selfish' DNA in Animal Mitochondria Offers A Possible Tool to Study Aging.


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