An enormous effort to decode the DNA of one of the most important laboratory animals — the fruit fly — ended in success this week as a collaboration of researchers from 16 nations announced the sequencing of 10 fly species’ genomes.
The research allows the extraordinary side-by-side comparison of the DNA of 12 species of fruit flies — two had already been decoded — as scientists search to understand the workings of individual genes and how those genes translate into specific physical characteristics.
Already the research has produced results. Scientists involved in the collaboration also announced the findings of their initial analysis: the discovery of thousands of new genes and other functional elements such as DNA segments responsible for turning genes on and off.
“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,” said Harvard Professor of Molecular and Cellular Biology William Gelbart, one of the project’s leaders.
The results were announced in a series of papers in the Nov. 8 issue of the journal Nature. The work, conducted by hundreds of researchers at more than 100 institutions, was supported by the National Institutes of Health’s National Human Genome Research Institute.
“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 National Human Genome Research Institute Director Francis Collins. “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.”
With a life span of just weeks, the fruit fly has been an important model organism in genetic studies for decades and has helped researchers unravel the rules that govern inheritance. Though there are many differences between fruit flies and humans, the two also share many genes that regulate the same biological functions.
The dozen fruit flies now sequenced all belong to the genus Drosophila, which has about 2,500 different species. Though some may think there’s little difference between fruit fly types, Gelbart said the genetic variation between fruit fly species is as large as that found among mammals. Fruit flies are adapted to life in a wide variety of conditions, from the desert to the rain forest, and have a wide range of physical traits.
With researchers spanning many institutions around the world, Gelbart said the project, officially called the Drosophila Comparative Genome Sequencing and Analysis Consortium, was at times a challenge to keep moving forward. Gelbart accomplished the feat together with eight other project leaders from the Broad Institute of Harvard and MIT, Cornell University, the University of California, Berkeley, the Lawrence Berkeley National Laboratory, the Agencourt Bioscience Corp., the University of Manchester, the National Institutes of Health, the University of Arizona, Indiana University, and the Computer Science and Artificial Intelligence Laboratory in Cambridge, Mass.
Among the findings from their side-by-side analysis of the dozen fruit fly genomes, researchers were able to determine that some genes are evolving faster than others. Genes involved in sex, taste, smell, detoxification, and metabolism seem to be evolving most rapidly. One example showed that a fly native to the Seychelles islands, with a limited universe of foods, is losing taste receptors much faster than other species.
Researchers also discovered the first known animal to lack genes to produce selenoproteins, a type of protein needed to get rid of excess selenium in the body, in the fruit fly species Drosophila willistoni.
The side-by-side comparison not only allowed the discovery of new genetic elements, it also allowed the correction of past errors. The results call into question more than 400 genes previously thought to encode proteins in the first species to be sequenced, Drosophila melanogaster.
The work, which will be available to other researchers, not only opens up numerous new avenues for inquiry, it creates an enormous bank of information available to future scientists probing life’s mysteries.
“Like most science, it raises more questions than it answers, but that’s OK,” Gelbart said.