Post by solidsquid on Aug 4, 2005 19:27:08 GMT -5
A mutagen that produces a beneficial mutation? You don't say...
Source - www.evowiki.org/index.php/Transposition
Source – Aminetzach, Y., Macpherson, M., and Petrov, D. (2005). Pesticide resistance via transposition-mediated adaptive gene truncation in Drosophila. Science 309, 764-767.
A little bit about transposons:
Source – www.hhmi.org/cgi-bin/askascientist/highlight.pl?kw=&file=answers%2Fgenetics%2Fans_029.html
Transposons were first discovered in maize in 1940 by Barbara McClintock, and were initially thought to be a feature only of Plants. McClintock noticed that the transposons caused insertion, deletion and translocation mutations. The discovery was initially greeted with widespread scepticism as geneticists could not make the discovery fit with the knowledge of genetics at that time. However, as more became known the significance of the discovery was recognised, and in 1983 McClintock was awarded the Nobel Price in Physiology or Medicine.
Source - www.evowiki.org/index.php/Transposition
To study adaptation, it is essential to identify multiple adaptive mutations and to characterize their molecular, phenotypic, selective, and ecological consequences. Here we describe a genomic screen for adaptive insertions of transposable elements in Drosophila. Using a pilot application of this screen, we have identified an adaptive transposable element insertion, which truncates a gene and apparently generates a functional protein in the process. The insertion of this transposable element confers increased resistance to an organophosphate pesticide and has spread in D. melanogaster recently.
Source – Aminetzach, Y., Macpherson, M., and Petrov, D. (2005). Pesticide resistance via transposition-mediated adaptive gene truncation in Drosophila. Science 309, 764-767.
A little bit about transposons:
Transposons, also known as transposable elements or mobile elements, are small segments of DNA ranging in length from 2,000 to 12,000 nucleotide pairs that can move around in a genome through transposition. They're categorized by the mechanism of transposition, or the way they reinsert themselves into new chromosomal sites.
Transposons also contribute to the evolution of new species. In fruit flies, some transposons have been shown to insert into specific places in the genome. The insertion of the transposon causes rearrangements in the chromosome, such as inversion or translocation of large segments of DNA. Once rearranged, the chromosome may be incompatible with the original chromosome, resulting in reproductive isolation that may ultimately give rise to a new species. These large changes in the genome caused by transposons are known as transposition bursts.
Scientists believe that vertebrate genomes originally evolved molecular defense mechanisms against the detrimental mutations caused by transposable elements. Over time, however, these defense mechanisms, which involve modifying DNA, may have been co-opted by the host genome for its own regulatory functions. The relationship between transposable elements and their host genomes may be something of an evolutionary arms race, with each trying to overcome the opponent's defenses. Although the evolutionary history of transposable elements is far from determined, the evidence suggests that transposons may play a significant role in the evolution of host genomes.
Transposons also contribute to the evolution of new species. In fruit flies, some transposons have been shown to insert into specific places in the genome. The insertion of the transposon causes rearrangements in the chromosome, such as inversion or translocation of large segments of DNA. Once rearranged, the chromosome may be incompatible with the original chromosome, resulting in reproductive isolation that may ultimately give rise to a new species. These large changes in the genome caused by transposons are known as transposition bursts.
Scientists believe that vertebrate genomes originally evolved molecular defense mechanisms against the detrimental mutations caused by transposable elements. Over time, however, these defense mechanisms, which involve modifying DNA, may have been co-opted by the host genome for its own regulatory functions. The relationship between transposable elements and their host genomes may be something of an evolutionary arms race, with each trying to overcome the opponent's defenses. Although the evolutionary history of transposable elements is far from determined, the evidence suggests that transposons may play a significant role in the evolution of host genomes.
Source – www.hhmi.org/cgi-bin/askascientist/highlight.pl?kw=&file=answers%2Fgenetics%2Fans_029.html