Integration of chlorophyll a fluorescence and photorespirometry techniques to understand production dynamics in macroaglal communities

Global declines of macroalgal beds in coastal waters have prompted a plethora of studies attempting to understand the drivers of change within dynamic nearshore ecosystems. Photosynthetic measurements are good tools for assessing the consequences of numerous stressors of macroalgae, but there is somewhat of a disconnection between studies that focus on organism‐specific ecophysiological responses and those that address causes and consequences of shifts in macroalgal productivity. Our goal is to highlight the applications of two complementary tools for measuring photosynthesis—variable chlorophyll a fluorescence and photorespirometry—and provide guidance for the integration of physiology and ecology to understand the drivers of change in macroalgal communities. Photorespirometry can provide an integrated measure of whole‐community metabolism, including an estimate of the physiological costs associated with stressors, while fluorescence‐based techniques provide point measures of the efficiency of the photosynthetic apparatus within communities. Variable chlorophyll a fluorescence does not provide an estimate of carbon balance or integrated photosynthesis across either whole plants or whole communities but can be used to estimate the contribution of individual community components in the dynamic subcanopy environment to help us understand the mechanisms underlying observed responses. We highlight the importance of the highly dynamic light environment within macroalgal communities and call for better integration of physiological techniques in an ecological context to enhance our understanding of the responses of whole communities to local and global stressors.     

Increased formation of cinnamoyl putrescines by fedbatch fermentation of cell suspension cultures of Nicotiana tabacum

The tobacco cell line TX1 (Nicotiana tabacum) accumulates up to 10 mg cinnamoyl putrescines/g dry weight. This level was further increased under various growth limiting conditions. The negative effect of accumulated phosphate on the optimal expression of cinnamoyl putrescine biosynthesis was prevented by the fedbatch fermentation technique. A batch fermenter yielded 160 mg cinnamoyl putrescines/1 while a phosphate fedbatch fermentation produced 400 mg/1. This was mainly due to the fact that P in the cells was kept low during the whole growth cycle.Abbreviation 2,4-D 2,4-Dichlorophenoxyacetic acid     

The structure and replenishment of rocky shore intertidal communities and biogeographic comparisons

Marine scientists have made many recent advances in understanding the connections between the structure of benthic communities, replenishment of populations through dispersal processes, and interactions with the nearshore water mass. In this review, some of the themes and models relating to these processes and interactions are discussed. Benthic–pelagic coupling models are in the early stages of development, but encompass oceanic processes such as upwelling and downwelling, the transport of larvae and their arrival back to shore to settle. Most current knowledge of these processes is based on a few taxa, especially barnacles and mussels. This is discussed with reference and comparison to macroalgae, which dominate much of the intertidal zone on temperate rocky shores, and have quite different life histories, transport and settlement processes. The role of key, habitat-dominating species is discussed, particularly their early life histories, with reference to the differences in community composition, nearshore dynamics and settlement processes in different countries. Finally, some suggestions are made for future work to fill gaps in understanding about rocky shore communities.     

Charaterization of twoMetabacterium sp. ...

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