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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Impacts of Ultraviolet Radiation on Host-Virus Dynamics of Common Blue Green Algea (Synechococcus)

EPA Grant Number: GF9501021
Title: Impacts of Ultraviolet Radiation on Host-Virus Dynamics of Common Blue Green Algea (Synechococcus)
Investigators: Audette, Charles T.
Institution: University of Rhode Island
EPA Project Officer: Broadway, Virginia
Project Period: January 1, 1995 through December 31, 1996
Project Amount: $26,891
RFA: STAR Graduate Fellowships (1995)
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology

Description:

Objective:

The purpose of this study is to demonstrate the effects of predicted increases in UV- B radiation, resulting from depletion of the ozone layer, on host-viral dynamics using blue green algae (Synechococcus), viruses of Synechococcus, and UV-B radiation. The goal of this study is to expand current knowledge of how virus adaptation occurs and its potential impacts on oceanic phytoplankton. The specific approach is to: 1) develop viral infected and non-infected cultures of bacteria free Synechococcus, 2) apply a combination of photosynthetically active radiation and UV-B irradiance at three measured dose levels for 12 hour intervals at constant temperature, 3) measure the effects of UV dose on algal cell abundance and cell viability using fluorescent microscopy counts of cells stained with propidium iodide and fluorescein diacetate, and measuring Chlorophyll abundance spectrophotometrically, and 4) measuring infectivity of the viruses using plaque assay method. The viral abundance and infectivity will also be monitored over time to determine if the virus propagation cycle is perturbed by ultraviolet radiation. This monitoring will determine whether the virus can adapt to increased ultraviolet radiation, and visual inspection of the virus will be performed using Transmission Electron Microscopy to determine if any morphological changes can be observed. Recent studies have shown that viruses in the ocean have been implicated in 1) termination of phytoplankton blooms, 2) playing a role in dissolved organic carbon production and particle flux, 3) as a food source, 4) as vectors of genetic transfer, 5) maintaining phytoplankton diversity, and 6) regulating primary productivity. While some viruses are extremely sensitive to UV-B radiation, others are induced to replicate by ultraviolet radiation, and the UV-B stress may render algal cells more susceptible to viral infection. This study will attempt to determine the effects of increased ultraviolet radiation, brought on by decreases in the ozone layer, on this important host-virus system.

Supplemental Keywords:

RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Aquatic Ecosystems & Estuarine Research, exploratory research environmental biology, Environmental Chemistry, Ecosystem/Assessment/Indicators, Chemical Mixtures - Environmental Exposure & Risk, Ecosystem Protection, Chemistry, Oceanography, Aquatic Ecosystem, Ecological Effects - Environmental Exposure & Risk, Ecological Effects - Human Health, tropospheric ozone, Atmospheric Sciences, Ecological Risk Assessment, Ecology and Ecosystems, Biology, Ecological Indicators, oceanic phytoplankton, effects of UV-B radiation on blue green algea, ozone depletion, host -viral dynamics of blue green algea, phytoplankton, ecosystem, blue green algea (Synechococcus), depletion of ozone layer, UV-B radiation

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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