Hewson Lab at Cornell


Team Aquatic Virus - Microbial Oceanography, P.I. Ian Hewson, Ph.D.

Metazoan Nanobiome Project

Shark Viruses

Collaboration with Willy Bemis, Shoals Marine Lab and Ecology  Evolutionary Biology
Joshua Moyer, Research Technician 2010-2011
Philip Thompson, Research Technician 2010 – 2011

Elasmobranchs are well known for their putative resistance to many types of disease. With the exception of a single report of viral dermatitis in dogfish (Leibovitz, 1985), there have been no investigations of viruses associated with shark tissues or blood. Hence, we initiated investigation into viruses in the spiny dogfish, Squalus sp., which is an abundant and cosmopolitan shark from the Gulf of Maine. Blood from 5 individual dogfish were collected in August 2011 from the Shoals Marine Lab, and transported frozen to the lab at Cornell. Initial investigations elucidated abundant virus-like particles in the blood via epilfluorescence microscopy. Viruses were then prepared for metagenomic sequencing via Illumina. We anticipate these data to provide interesting new information about DNA viruses within elasmobranchs, and may provide clues about their role in host disease and disease resistance.

Diversity of viruses associated with the echinoderm Asterias sp.

Philip Thompson, Technician 2011-present
William Aragundi, Undergraduate Researcher Fall 2011

Viruses are known to infect organisms from bacteria to whales, causing substantial mortality, influencing the composition of host communities through density dependent and species specific mortality, and releasing particulate C into the DOC pool. While viruses of aquacultural and fisheries-relevant invertebrate taxa have been documented for decades, the viral role in causing mortality of several invertebrate groups has not yet been investigated. In particular, there are currently no described viruses of echinoderms, which form keystone species within coastal marine habitats.
We initiated investigations into viral communities within echinoderm tissues as a first step in understanding their role in host ecology. Three echinoderm taxa were targeted as representative organisms of the phylum: Strongylocentrotus sp (the green urchin); Mellita sp. (sand dollar); and Asterias sp. (seastar). Several individual animals were collected in August 2011 from Appledore Island, Gulf of Maine, and transported alive to the lab at Cornell University. There, they were frozen at -80oC.
An initial investigation into possible presence of viral particles by SYBR Green I epifluorescence microscopy was conducted in Fall 2011. Animals were dissected into organs (pyloric caeca, gonad, stomach, aristotle’s lantern, madreporite, theca, and esophagus), and each section was prepared for microscopy separately. This investigation identified the presence of virus-like particles in gonad tissue of the urchin and sand dollar, and within pyloric caeca of the sea star.
Metaviromes were attempted for these three tissue types following a standard approach (Thurber et al., 2009). Despite extensive efforts, amplification of DNA extracted from viruses in the urchin and sand dollar were unsuccessful, however amplicons were obtained from the seastar pyloric caeca. These are currently being sequenced by illumina. We hope that data from this study will generate interesting questions about the roles of viruses in echinoderm ecology.
sea fan viruses

Characterization of viral assemblages associated with the Gorgonia ventalina holobiont

Collaboration with C. Drew Harvell, Ecology & Evolutionary Biology
Colleen Burge, Postdoctoral Fellow, Ecology & Evolutionary Biology
Julie Brown, Graduate Student, Microbiology
Ashley Campbell, Rotation Graduate Student, Microbiology, Spring 2010
Courtney Couch, Graduate Student, Ecology & Evolutionary Biology
Morgan Mouchka, Graduate Student, Ecology & Evolutionary Biology
Mizue Naito, Rotation Graduate Student, Microbiology, Spring 2011
Brenna LaBarre, Undergraduate Researcher, Fall 2010 –
John Means, Undergraduate Researcher, Fall 2009

The diversity and function of viruses in coral holobionts has only recently received attention.
The non-reef building gorgonian octocoral, Gorgonia ventalina, is a major constituent of
Caribbean reefs. We investigated viral communities associated with G. ventalina tissues
to understand their role in gorgonian ecology. Pyrosequencing was used to prepare
a total of 514,632 sequence reads of DNA- and RNA-based mixed community viral genomes
(metaviromes). RNA viral assemblages were comprised of primarily unidentifiable reads, with
most matching host transcripts and other RNA metaviromes. DNA
metaviromes were comprised of contiguous sequences (contigs) that matched primarily metazoan and bacterial proteins. Only ~5% of contigs matched viral proteins which were primarily cyanophage and viruses of Chlorella and
Ostreococcus. Our results confirm that DNA and RNA viruses comprise a component of the gorgonian holobiont, suggesting that they may play a role in the ecology of G. ventalina.

Amphipod viruses

Collaboration with Lars Rudstam and Jim Watkins, Natural Resources
Philip Thompson, Research Technician, 2010 – 2011

The benthic amphipod Diporeia sp. inhabits the Laurentian Great Lakes, where it plays a crucial role in benthic biogeochemistry, shredding allochthonous detritus, and thus contributing to benthic organic matter regeneration. Over the past decade, populations of this amphipod have been declining in some lakes, where the decline is unrelated to food availability, predation pressure, or otherwise obvious factors. Because viruses may play a role in the ecology of the crustacean, similar to our investigations of copepod and Daphnia viruses, we are conducting metagenomic sequencing of viruses collected from impacted (Owasco Lake, Lake Huron) and unimpacted lake (Lake Superior) populations. Amphipods were collected during several times in the last decade, frozen, and were recently processed for metagenomics. The information gained from this project will provide new insight into the diversity of viruses associated with crustaceans, and may elucidate deleterious viral components which will facilitate further investigation into their roles in amphipod ecology.


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