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A Novel Method for Extracting Protoplasts from Large Brown Algae 总被引:2,自引:0,他引:2
Protoplasts have been isolated without the application of walldegrading enzymes from three large brown algal species: Macrocystisangustifolia, Ecklonia radiata and Durvillaea potatorum. Thecentral feature of this new protocol is the removal of wall-boundcalcium by substitution with sodium from the isolation medium.The new protocol is specific for cortex and inner meristodermcell walls with highest yields obtained from meristematic oryoung tissue. Protoplasts, extracted with this method, are approximately510 µm in diameter with viability estimates rangingfrom 7386%. Consistent yields of 107 protoplasts g1fresh weight have been obtained within 23 for all threespecies and this compares favourably with yields achieved usinga conventional enzyme-based system. Key words: Brown algae, protoplasts, alginate, calcium, enzymes 相似文献
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C. D. HEPBURN D. W. PRITCHARD C. E. CORNWALL R. J. McLEOD J. BEARDALL J. A. RAVEN C. L. HURD 《Global Change Biology》2011,17(7):2488-2497
Mechanisms for inorganic carbon acquisition in macroalgal assemblages today could indicate how coastal ecosystems will respond to predicted changes in ocean chemistry due to elevated carbon dioxide (CO2). We identified the proportion of noncalcifying macroalgae with particular carbon use strategies using the natural abundance of carbon isotopes and pH drift experiments in a kelp forest. We also identified all calcifying macroalgae in this system; these were the dominant component of the benthos (by % cover) at all depths and seasons while cover of noncalcareous macroalgae increased at shallower depths and during summer. All large canopy‐forming macroalgae had attributes suggestive of active uptake of inorganic carbon and the presence of a CO2 concentration mechanism (CCM). CCM species covered, on average, 15–45% of the benthos and were most common at shallow depths and during summer. There was a high level of variability in carbon isotope discrimination within CCM species, probably a result of energetic constraints on active carbon uptake in a low light environment. Over 50% of red noncalcifying species exhibited values below ?30‰ suggesting a reliance on diffusive CO2 uptake and no functional CCM. Non‐CCM macroalgae covered on average 0–8.9% of rock surfaces and were most common in deep, low light habitats. Elevated CO2 has the potential to influence competition between dominant coralline species (that will be negatively affected by increased CO2) and noncalcareous CCM macroalgae (neutral or positive effects) and relatively rare (on a % cover basis) non‐CCM species (positive effects). Responses of macroalgae to elevated CO2 will be strongly modified by light and any responses are likely to be different at times or locations where energy constrains photosynthesis. Increased growth and competitive ability of noncalcareous macroalgae alongside negative impacts of acidification on calcifying species could have major implications for the functioning of coastal reef systems at elevated CO2 concentrations. 相似文献
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Protein turnover in relation to maintenance metabolism at low photon flux in two marine microalgae 总被引:2,自引:0,他引:2
Acclimation to very low photon fluxes involves adjusting a suite of physiological characteristics that collectively elicit a physiological response. Facilitating such changes is pro‐tein turnover. Dunaliella tertiolecta (Butcher) and Phaeodactylum tricornutum (Bohlin) were grown in turbidostats at a range of photon fluxes between 2 and 300 µmol photons m?2 s?1. The kinetics of pulse‐chase labelling of the protein with 3H showed that (1) two protein pools were present, one of which turned‐over rapidly (hours), and a second which turned over more slowly (days); and (2) protein turnover rates were slower in P. tricornutum than in D. tertiolecta. Phaeodactylum tricornutum had a lower maintenance coefficient for protein turnover than D. tertiolecta, and correspondingly a smaller proportion of its respiratory demands (30%) were associated with protein turnover than in D. tertiolecta (36%). There appears to be a correlation between lower metabolic activity, requiring lower protein concentrations, and an associated decreased cost of maintenance processes in P. tricornutum compared to D. tertiolecta. Differences between protein turnover rates and maintenance metabolic costs may be one of the photo‐acclimation strategies that determine which photon niches microalgae can successfully exploit. 相似文献
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The lower limit of photon fluence rate for phototrophic growth: the significance of 'slippage' reactions 总被引:3,自引:0,他引:3
Abstract. The role of 'slippage' reactions, in the form of passive H+ uniport through CF0 -CF1 , ATP synthetase and breakdown of the S2 and S3 intermediates of O2 evolution, is considered in relation to the growth of phototrophic organisms at low photon fluence rates. Analysis of the limited data available suggests that adaptation (phenotypic or genotypic) to low photon fluence rates is accompanied by an increase in the ratio of light-absorbing pigments to the (potentially slippage-inducing) photosystem two units and CF0 -CF1 ATP synthetases. Furthermore, organisms which are genotypically adapted to high photon fluence rates do not, when grown at low photon fluence rates, achieve the same low ratio of reaction centres to total light-harvesting pigments as is found in phototrophs genotypically adapted to low photon fluence rates. The limits to, and energy costs of, such a mechanism of adaptation to low photon fluence rates are also discussed. 相似文献
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Carbon Isotope Discrimination and the CO2 Accumulating Mechanism in Chlorella emersonii 总被引:1,自引:0,他引:1
The relationship between the CO2 accumulating mechanism andcarbon isotope discrimination has been investigated in the unicellulargreen alga Chlorella emersonii. Growth of Chlorella at highC02 levels (5%) which repress the activity of the CO2 accumulatingmechanism results in more negative 13C values. The data presentedin this paper suggest that it is possible to induce the accumulatingmechanism by nitrogen limitation as well as by carbon limitation.Activity of the accumulating mechanism, irrespective of whetherit is induced by C or by N limitation, is accompanied by 13Cvalues considerably less negative than those of cells whichdo not possess such a mechanism. It is suggested that the CO2accumulating mechanism results in essentially a closed systemin which the inherent isotope discrimination by RuBP carboxylaseis not expressed. 相似文献
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ADAPTATION OF UNICELLULAR ALGAE TO IRRADIANCE: AN ANALYSIS OF STRATEGIES 总被引:17,自引:1,他引:16
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