Assessing the Diversity and Specificity of Two Freshwater Viral Communities through Metagenomics

Transitions between saline and fresh waters have been shown to be infrequent for microorganisms. Based on host-specific interactions, the presence of specific clades among hosts suggests the existence of freshwater-specific viral clades. Yet, little is known about the composition and diversity of the temperate freshwater viral communities, and even if freshwater lakes and marine waters harbor distinct clades for particular viral sub-families, this distinction remains to be demonstrated on a community scale

A historical overview of the Pavilion Lake Research Project-Analog science and exploration in an underwater environment

As humans venture back to the Moon, or onward to near-Earth objects and Mars, it is expected that the rigors of this exploration will far exceed those of Apollo. Terrestrial analogs can play a key role in our preparations for these complex voyages, since in addition to their scientifi c value, analogs afford the exploration community a means to safely prepare and test exploration strategies for future robotic and human planetary missions. Many relevant analog studies exist, and each is focused on a particular aspect of strategic development. Some analog programs such as the Pavilion Lake Research Project (PLRP) present the opportunity to investigate both real scientifi c and real exploration scenarios in tandem. The activities of this research program demand the use of techniques, tools, and strategies for underwater scientifi c exploration, and the challenges associated with the scientifi c exploration of Pavilion Lake are analogous to those human explorers will encounter on other planetary and small solar system bodies. The goal of this paper is to provide a historical synopsis of the PLRP's objectives, milestones, and contributions to both the scientifi c and exploration community. Here, we focus on detailing the development and deployment of an integrated science and exploration program with analog application to our understanding of early Earth systems and the preparation for future human space exploration. Over a decade of exploration and discovery is chronicled herein. © 2011 The Geological Society of America.link_to_subscribed_fulltex

Viruses in Glacial Environments

Viruses play a central role in glacial microbial communities. Prokaryotes in glacial environments support surprisingly large viral communities, which, in turn, have a considerable impact on the prokaryotic communities. Through the lysis of host cells and by lowering the growth efficiency of prokaryotic communities, viruses substantially alter the carbon cycling in glacial environments. Despite many similarities with viruses in other habitats, the unique characteristics of glacial environments have accentuated certain features in glacial viruses and their interactions with their hosts, e.g. low viral decay rates in supraglacial viruses as a mechanism for overcoming low host contact rates in systems with low prokaryotic abundances, virus-specific temperature adaptation that differ from that of the host, and virus-mediated transfer of CRISPR arrays that confer immunity against superinfection. Current literature suggests that viral communities in glacial environments are as genetically diverse as those in other environments and, with recent technological advances in environmental genomics and bioinformatics, we are posed to tackle the next great challenge in viral ecology of identifying and quantifying the dynamics of individual virus?host pairs in environmental samples