This article talks about transposable elements (TEs) that may be beneficial to fruit flies. In chapter 21, we learned that transposable elements are segments of DNA that can move from one location to another. They are inherently mobile. The ends of TEs have inverted repeats which are short DNA sequences that are present in many copies throughout the genome. All organisms contain pieces of DNA that aren't necessarily theirs, aka TEs. The finer points about factors that govern the spread of transposable elements within a population are still very unclear. The University of Veterinary Medicine, Vienna has work that may help us increase our information about the intracellular battle that is constantly being played out between the host and invading DNA.
With new sequencing technologies, Robert Kofler and Andrea Betancourt in Schlotterer's group at the Vetmeduni Vienna's Institute of Population Genetics, were able to examine the difference in TEs in a small population of fruit flies. All the TEs in that population were catalogued. The researchers found how often TEs occur at certain sites of insertion as well.
The flies contain TEs at many sites throughout the genome despite there being many insertion sites that are actually only affected in few individuals. Researchers say that these sites were sites of recent insertion and soon we will be able to find out whether the elements are maintained there. The majority of TEs are somehow purged before they become established. Schlotterer summarized the results: "the genome is like a record of past wars between hosts and the parasitic DNA. There have been waves of attacks and the majority of them have been repelled, with only few transposable elements managing to survive and spread throughout the population."
Many sites of insertion that were more recurrent in the population than would have been expected for their age, were also found . This means that there is positive selection for TEs at these sites. This suggests that insertion has a beneficial effect on the host.
We can conclude that TEs aren't like parasites at all, but actually very helpful. They provide organisms with an opportunity to increase their genetic collection. This is important and can be very advantageous in helping them overcome future challenges.
With new sequencing technologies, Robert Kofler and Andrea Betancourt in Schlotterer's group at the Vetmeduni Vienna's Institute of Population Genetics, were able to examine the difference in TEs in a small population of fruit flies. All the TEs in that population were catalogued. The researchers found how often TEs occur at certain sites of insertion as well.
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| This picture shows the function of a transposable element. It basically carries the genes and gets inserted into the bacterial chromosome. |
The flies contain TEs at many sites throughout the genome despite there being many insertion sites that are actually only affected in few individuals. Researchers say that these sites were sites of recent insertion and soon we will be able to find out whether the elements are maintained there. The majority of TEs are somehow purged before they become established. Schlotterer summarized the results: "the genome is like a record of past wars between hosts and the parasitic DNA. There have been waves of attacks and the majority of them have been repelled, with only few transposable elements managing to survive and spread throughout the population."
Many sites of insertion that were more recurrent in the population than would have been expected for their age, were also found . This means that there is positive selection for TEs at these sites. This suggests that insertion has a beneficial effect on the host.
We can conclude that TEs aren't like parasites at all, but actually very helpful. They provide organisms with an opportunity to increase their genetic collection. This is important and can be very advantageous in helping them overcome future challenges.
Would this cause evolutionary processes to go faster?
ReplyDeleteI can't say it would make them go faster, for sure; but it is evident that TEs are contributing to evolution. What with their positive selection and increasing organisms' genetic collection.
ReplyDelete