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Nick Gezon defends his thesis on CRESS-DNA viral consortium of quagga mussels and Lake Michigan sediments

Nick Gezon defends his thesis on CRESS-DNA viral consortium of quagga mussels and Lake Michigan sediments

On December 1, 2017, graduate student Nicholas Gezon successfully defended his Master’s thesis, titled “Surveying the Circular Rep Encoding Single Stranded (CRESS) DNA viral consortium found in invasive quagga mussels (Dreissena rostriformis bugensis) and sediments of the central Lake Michigan benthos”. His thesis committee members included Drs. Kevin Strychar, Charlyn Partridge, and James McNair of AWRI, as well as Dr. Doug Haywick of the University of South Alabama and Dr. Ian Hewson of Cornell University.

Nick’s research focused on the Lake Michigan benthic community which has shifted dramatically in the past decades, partially due to the establishment of numerous nonindigenous species. He was specifically interested in characterizing an unknown and poorly understood aspect of the Lake Michigan benthic community, the Circular Rep Encoding Single Stranded-DNA (CRESS-DNA) viral consortium found in the notorious invasive species the quagga mussels (Dreissena rostriformis bugensis). He was interested in what CRESS-DNA viruses these invaders may be moving between ecosystems and what CRESS-DNA viruses were historically present. For his thesis project, Nick surveyed the CRESS-DNA viruses found in both quagga mussels and sediment cores of the offshore Lake Michigan benthos to compare what viruses were historically present and what viruses are around now and interacting with the current invasive species. He found 54 novel CRESS-DNA virus-like sequences in the quagga mussels and sediments cores of the offshore benthos of Lake Michigan. From these results he focused on a particular CRESS-DNA virus-like sequence of interest (found only in quagga mussels) to quantify the abundance and distribution using qPCR. Nick found this particular CRESS-DNA virus-like sequence to be present only in quagga mussels of the offshore Lake Michigan benthos and not in quagga mussel samples collected in Muskegon Lake and samples from the European expanded range in the Rybinsk Reservoir in Russia. He concluded that this particular CRESS-DNA virus-like sequence is likely endemic to the offshore waters of Lake Michigan and was unlikely brought in when the quagga mussels invaded Lake Michigan. His results bring up interesting future research questions about CRESS-DNA aquatic viral ecology including what organisms these CRESS-DNA viruses are specifically infecting.

Nick hopes to continue a career in aquatic ecology focusing on broader research in invasion ecology and disease ecology as well as sharing his passion for ecology with others through teaching.

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