How evolution has shaped fruit fly genomes revealed

November 14th, 2007 - 10:17 am ICT by admin  
The research group, supported by the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), has revealed that their analysis has resulted in the identification of thousands of novel genes and other functional elements in the insects’ genomes.

The researchers also say that their study describes how evolution has shaped the genomes of fruit flies, which are considered to be important models for genetic research.

“This remarkable scientific achievement underscores the value of sequencing and comparing many closely related species, especially those with great potential to enhance our understanding of fundamental biological processes,” said Nature magazine quoted Dr. Francis S. Collins, director of NHGRI, as saying.

“Thanks to the consortium’s hard work, scientists around the world now have a rich new source of genomic data that can be mined in many different ways and applied to other important model systems as well as humans,” he added.

The work was carried out by hundreds of scientists from more than 100 institutions in 16 countries. They found that, at first glance, the genomes of the various types of fruit flies appeared quite similar.

However, they added, a more detailed examination revealed that only 77 per cent of the approximately 13,700 protein-coding genes in D. melanogaster were shared with all of the other 11 species.

According to the scientists, different regions of the fruit fly genomes, including protein-coding genes and gene families, are evolving at different rates. The findings suggest that these particular protein-coding genes likely evolve in the fruit fly genome as a result of adaptation to changing environments and sexual selection.

The researchers also say that the genes that produce selenoproteins, which are responsible for reducing excess amounts of the mineral selenium, appear to be absent in the D. willistoni genome.

D. willistoni, according to the researchers, seems to be the first animal known to lack Selenoproteins, which are present in all animals, including humans. They, however, suggest that the insect may possibly encode selenoproteins in a different way, opening a new avenue for further research.

A project leader and co-author for the studies, Dr. William M. Gelbart, of Harvard University in Cambridge, Massachusetts, said: “The availability of the 12 fruit fly genomes resulted in a dramatic increase in resolution allowing us to examine how evolution has fine-tuned biological processes. Our work shows that discovery power increases with the number of genomes available for comparison.”

The genomes of 12 fruit fly species were also used to identify thousands of new genes and other functional elements, and thus it is believed that this work will bolster efforts to find all functional elements in the reference genome sequence of D. melanogaster.

“Comparing the 12 fruit fly genomes allowed us to recognize evolutionary signatures characteristic of each function. These signatures enabled us to distinguish and identify thousands of new functional elements,” said Dr. Manolis Kellis of the Massachusetts Institute of Technology in Cambridge, Massachusetts.

The researchers, specifically, used the evolutionary signals to discover 1,193 new protein-coding sequences and called into question 414 sequences previously reported as protein-coding genes in the D. melanogaster genome sequence.

They also found hundreds of novel functional elements across the 12 fruit fly genomes such as non-protein coding genes, regulatory elements involved in the control of gene transcription, and DNA sequences that mediate the structure and dynamics of chromosomes.

“Our analyses only represent a small portion of questions that can be answered in the context of these 12 species. Today’s findings represent an important starting point for future research aimed at understanding the function of the genome features we discovered and their relevance to the human genome,” said Dr. Andrew G. Clark from Cornell University in Ithaca, New York. (ANI)

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