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Seminar Details

Diatom host-virus dynamics and the marine silicon cycle: Linking molecular ecology with marine biogeochemistry

Date

12/03/2019

Lecturers

Dr. Chana Kranzler - Dept. of Marine and Coastal Sciences, Rutgers University, USA

Abstract

Diatoms, one of the most globally distributed and ecologically successful groups of organisms in the modern ocean, contribute upwards of 40% of the total marine primary productivity. With their obligate silicon (Si) requirement for cell wall formation, diatoms effectively couple the Si and carbon (C) cycles, converting dissolved Si into biogenic silica that ballasts substantial vertical flux of C out of the euphotic zone into the mesopelagic and deep ocean. Viruses are key players in ocean biogeochemical cycles, yet little is known about how viruses specifically impact diatom populations. We found that Si limitation drives viral infection and mortality in diatoms in the highly productive coastal waters of the California Current Ecosystem. Early, active and lytic stages of viral infection were diagnosed across a gradient of Si stress using a suite of chemical and biological measurements alongside metatranscriptomic analyses of cell-associated diatom viruses and targeted, quantitative RT-PCR of free, extracellular viruses. In Si-limited cultures of the centric, bloom-forming diatom, Chaetoceros tenuissimus, viral-induced mortality was accelerated, with unimpaired viral production. Together, these findings contextualize viruses within the ecophysiological framework of Si availability and diatom-mediated biogeochemical cycling.

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