Biologists from the University of Texas Medical Center offered a new explanation for ultrafast evolutionary changes that have occurred and are occurring in different species. One of the problems in the theory of evolution — the lack of speed of naturally occurring mutations that provide variability, which is due to the selection of "converted" to the emergence and development of new species or subspecies.
Replacing the individual "letters" in different "words" that make up genes, is too slow to ensure the rapid changes taking place and taking place, at times, with certain species.
Particularly interesting, as one, in fact, the kind of lightning so (by the standards of the evolution of nature) there are lots of "modifications" distinguished appearance (long noses or tails, color and other things). The genetic mechanism of this transformation, biologists have found in Texas, based on the analysis of the DNA of dogs of various breeds.
Biologists have used the computer to find a correlation between certain genetic differences and differences in the appearance of dogs in particular — the length and shape of their nose. So they figured out that the key to super-fast evolutionary jumps are the portions of genes, known as "tandem repeat sequences" (tandem repeat sequences).
These are fragments of code that looks like a long repetition of one and the same "words" (for example ACTACTACT). Mutations in such areas occur when copying when an error while reading or writing to the chain inserts an extra (or vice versa — is removed), the "standard" link (ACT). These errors affect the production of certain proteins and cells, in turn, parameters for various animals, such as the same length of the nose.
It sounds funny, but it turned out that in some cases the chain ACTACT will mean a short nose, and ACTACTACTACT in the same location of the genetic code — a long one.
The study's authors point out that mutations in the tandem repeat sequences occur in the 100 thousand times more than the occasional replacement of single letters, and so may well claim to be the main engine of the evolution of species. The next step Texas scientists — to test the hypothesis on other animals.
Battery News, 27/12/2004 20:58