Document Detail

The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats.
MedLine Citation:
PMID:  11536898     Owner:  NASA     Status:  MEDLINE    
Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation. Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems. As both photosynthesis and UV fluxes are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats. In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp.) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes in the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations.
C S Cockell; L J Rothschild
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Photochemistry and photobiology     Volume:  69     ISSN:  0031-8655     ISO Abbreviation:  Photochem. Photobiol.     Publication Date:  1999 Feb 
Date Detail:
Created Date:  1999-10-21     Completed Date:  1999-10-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376425     Medline TA:  Photochem Photobiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  203-10     Citation Subset:  S    
Ecosystem Science and Technology Branch, NASA Ames Research Center, Moffett Field, CA, USA.
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MeSH Terms
Algae, Green / metabolism*,  radiation effects
Carbon / metabolism
Chlorophyll / metabolism
Circadian Rhythm
Cyanobacteria / metabolism*,  radiation effects
Environmental Microbiology*
Geologic Sediments / microbiology*
Photosynthesis / radiation effects*
Ultraviolet Rays*
Reg. No./Substance:
1406-65-1/Chlorophyll; 479-61-8/chlorophyll a; 7440-44-0/Carbon

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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