| Metabolic plasticity of nitrogen assimilation by Porphyra umbilicalis (Linnaeus) Kützing |
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| 作者姓名： | Jang K.Kim George P.Kraemer Charles Yarish |
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| 作者单位： | Departments of Ecology and Evolutionary Biology and Marine Sciences,University of Connecticut,1 University Place,Stamford,CT 06901,USA;Department of Environmental Studies,Purchase College,735 Anderson Hill Road,Purchase,NY 10577,USA |
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| 基金项目： | Connecticut Sea Grant College Program，National Oceanic and Atmospheric Administration's National Marine Aquaculture Initiative，awards to J.K.Kim from the Department of Ecology and Evolutionary Biology |
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| 摘 要： | The physical stresses associated with emersion have long been considered major factors determining the vertical zonation of intertidal seaweeds.We examined Porphyra umbilicalis(Linnaeus) Kützing thalli from the vertical extremes in elevation of an intertidal population(i.e.upper and lower intertidal zones) to determine whether Porphyra thalli acclimate to different vertical elevations on the shore with different patterns of nitrate uptake and nitrate reductase(NR) and glutamine synthetase(GS) activities in response to different degrees of emersion stress.We found that the nitrate uptake and NR recovery in the emersed tissues took longer in lower intertidal sub-population than in upper intertidal sub-population;and GS activity was also significantly affected by emersion and,interestingly,such an activity was enhanced by emersion of thalli from both upper and lower intertidal zones.These results suggested that intra-population variability in post-emersion recovery of physiological functions such as nutrient uptake and NR activity enables local adaptation and contributes to the wide vertical distribution of P.umbilicalis.The high GS activity during periodic emersion stress may be a protective mechanism enabling P.umbilicalis to assimilate nitrogen quickly when it again becomes available,and may also be an evidence of photorespiration during emersion.
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| 关 键 词： | emersion glutamine synthetase nitrate reductase nitrogen assimilation Porphyra |
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