Publications & Resources
Environmental metagenomics—
Characterizing viral communities in remote Antarctic lakes
Centro de Biologia Molecular Severo Ochoa (CSIC-UAM)
Madrid, Spain
What was the role of 454 Sequencing in the viral metagenomics study? How did the technology change the way you approached your research?
We had the unique opportunity to participate in an Antarctic expedition funded by the Spanish Polar Programme. Our role was to study viruses in Antarctic lakes located in Byers Peninsula (Livinston Island), designated as an Antarctic Specially Protected Area because of its ecological interest. 454 Sequencing technology allowed us to address this project in a different and broader way, being able to determine the genetic composition of the viral community present in these Antarctic lakes, as an alternative to identifying a limited number of viruses by PCR amplification. The availability of 454 Sequencing was critical to get a broad picture of the diversity of viruses in this interesting ecosystem and allowed us to identify viruses not described previously.
What have been the implications of this discovery in your field of research?
Recent environmental studies have uncovered the abundance of viruses on Earth and the role they play in the control of microbial communities. However, the nature of viruses adapted to extreme environmental conditions in Antarctica was unknown. Our study describes for the first time a metagenomic analysis of the viral community (virome) present in lakes of Antarctica. In contrast with the low biological diversity expected in the polar regions, we identified a striking genetic diversity of viruses in this Antarctic lake, distributed among the highest number of viral families reported to date in natural aquatic systems. Also remarkable is that, in contrast to other aquatic viromes that are dominated by prokaryotic viruses (bacteriophages), this Antarctic virome had a large proportion of eukaryotic viruses including small ssDNA viruses that have not been found in other aquatic systems. Byers Peninsula is one of a few areas in Antarctica that is not covered with snow during the short Austral summer, and we were able to compare the viruses found in the ice-covered lake in the spring with those present in the lake after the ice melt in summer. Interestingly, the viral community shifted from a high proportion of small ssDNA viruses in ice-covered lake to a virome dominated by large dsDNA viruses in summer. To my knowledge, this is the first time that a metagenomic approach has been used to describe seasonal changes in a viral community.
What's your next step? How do you plan to use 454 Sequencing in the future?
Our description of the high genetic diversity of Antarctic viruses is the first step towards understanding the role that viruses play in these extreme ecosystems. Although our study has shed light into the viral community populating Antarctic lakes, it has also opened many questions that will need to be addressed in the future. Antarctica has been isolated for millions of years and there is an intense debate regarding the endemism in Antarctic biological systems. We would like to find out whether these viruses have evolved in isolation independently from other viral communities elsewhere in the planet or whether they have been re-introduced in Antarctica when the ice started to melt in a few regions after the last glacial maximum, estimated to occur 20,000 years ago. We are planning to sample other lakes in our next Antarctic expedition and to use the 454 sequencing technology to compare the viral communities from other locations in this unique ecosystem.
To view the publication abstract, click here.
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