Cinnu, Murugan , Patrick, Neale .
Biological Weighting Functions for quantifying the effect of UV radiations on growth, and photosynthesis of Ulva grown under high light and low light environments.
Solar ultraviolet radiations (UV) (290-400 nm) is a significant stressor in aquatic environments. It has adverse effect on photosynthesis, growth and damages DNA in the primary producers in most aquatic ecosystems. Quantitative assessments of the effect of UV in the aquatic environment require a set of weights ( a biological weighting function or BWF) that specify the biological effectiveness of UV radiation as a function of wavelength. A detailed BWF is particularly important for assessing the effect of enhanced UV-B (290-320 nm) due to Ozone depletion. Because, microalgal photosynthesis reflects the interacting effects of multiple UV and photosynthetically available radiation (PAR, 400-700 nm), polychromatic exposures are used to estimate BWFs for UV inhibition of photosynthesis. In this study, we have selected a floating green algae Ulva which is acting as a biofilter in an integrated mariculture system, where the radiation regimes and fluctuates. The principle objective of my study is to determine the BWFs for UV inhibition of photosynthesis in Ulva collected around SERC (Rhode River) in the Chesapeake Bay. The kinetics of inhibition and recovery will be defined using active fluorometry measurements of the quantum yield of Photosystem II (PSII) before, during, and after the exposure to UV. Structural changes induced by UV radiation on the O2 evolving polypeptides (33,23 and 15 Kda) of thylakoid membrane and the large (55 Kda) and the small (15 Kda) polypeptides of RuBPCase can be measured as SDS-PAGE using linear gradient of 8-18%. Cultures are sampled every day for Chla fluorescence induction kinetics, Electron transport and RuBPCase activities. As a result, these data will provide an excellent base for modeling work (biological responses to UV) and also support to identify the site of UV damage in photosystems and depth of damage on primary production in an aquatic ecosystem.
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1 - Center for Plant Conservation, HB Estate, 125, Linghi Chetty St, Chennai, TN, 600 001, India
2 - Smithsonian Environmental Research Center, PO Box 28, Edgewater, MD, 21037, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Stevens 1/Hilton
Date: Tuesday, July 10th, 2007
Time: 9:00 AM