在水生与气生状态下石莼光合作用对光照和温度的响应(英文)

如何对付由于高潮时的水生状态与低潮时的气生状态高频率循环所导致的不同环境条件 ,是潮间带海藻的光合作用所面临的独特问题。对采自汕头沿岸的石莼 (Ulvalactuca)在水生和气生不同状态下光合作用对光照和温度的响应特性进行了测定 ,以探讨这种常见的潮间带绿藻在潮汐循环背景下的光合特性。在气生状态下 ,光饱和净光合速率 (Pmax)随气生暴露时间的变化模式可以很好地用三次方程进行描述 ,而温度影响方程的系数 ;当水分损失为 1 5 %时 ,石莼的Pmax增加至最大值 ,然后Pmax随进一步脱水而下降 ,

海洋酸化的生理生态效应及其与升温、UV辐射和低氧化的关系

海洋以每小时超过100万t的速率,从大气中吸收矿物燃料衍生及人类排放的CO2,引起海水pH下降,导致海洋酸化.与此同时,全球变暖引起海洋升温,使得上部混合层变浅,导致该层内营养盐减少,浮游生物接受可见光和UV的辐射量增加,并且使得O2的溶解度降低,引起低氧化.这些海洋变化问题在全球范围内普遍存在,然而,不同海域的环境响应和生态效应有所不同.主要综述全球海洋酸化问题研究进展,突出升温、UV辐射影响下的酸化效应,进而结合南海相关的研究进展分析未来研究动态.国家自然科学基金(41721005,41720104005,41430967);;国家基金委-山东省联合基金项目(U1606404

Exogenous carbon acquisition of photosynthesis in Porphyra haitanensis (Bangiales, Rhodophyta) under emersed state

The photosynthetic performances of Porphyra haitanensis thalli were investigated in order to understand its mechanisms for exogenous carbon acquisition during emersion at low tide. The emersed photosynthesis was studied by altering the pH value in the water film on the thalli surface, treating them with carbonic anhydarase inhibitors (acetazolamide and 6-ethoxyzolamide), adjusting the CO2 concentrations in the air, and comparing the theoretical maximum CO2 supply rates within the adherent water film with the observed photosynthetic CO2 uptake rates. It was found that the principal exogenous inorganic carbon source for the photosynthesis of P. haitanensis during emersion was atmospheric CO2. The driving force of CO2 flux across the water film was the CO2 concentration gradient within it. Carbonic anhydrase accelerated both extracellular and intracellular CO2 transport. The emersed photosynthesis of P. haitanensis was limited by the present atmospheric CO2 level, and would be enhanced by atmospheric CO2 rise that would trigger global warming

Seasonal variation of photosynthetic capacity in Sargassum horneri

Photosynthesis on a dry weight basis was measured with a differential gas-volumeter in Sargassum horneri to see its seasonal changes. Photosynthetic activity in leaves of S. horneri showed two peaks a year, one in November and the other in March. The seasonal pattern of photosynthesis was similar to that reported for growth of this species. Net photosynthetic rates of the upper leaves were higher than those of the lower leaves in all months except June, when the plants became mature. In June, net photosynthetic rate in the lower leaves was higher than that in the upper ones. An adaptive shift of net photosynthetic response to temperature was observed with a decline in seawater temperature from July to December. Besides temperature, growth stage and nutrient conditions in the sea also accounted for considerable seasonal photosynthetic variability

干出和紫外辐射对坛紫菜光合作用的影响

以坛紫菜叶状体为材料,研究了干出和阳光紫外辐射(uVr)对其光合作用的影响.长时间干出和阳光uVr不能进一步诱导藻体合成紫外吸收物质,而且uVr对干出藻体的叶绿素A和类胡萝卜素合成有抑制作用.uVr显著抑制干出状态下藻体光系统II(PSII)的有效光化学效率和藻体的光合固碳速率,而且对光合活性的抑制作用随失水率的增大而增强.国家自然科学基金重点资助项目(批准号:90411018

Photosynthetic recovery of desiccated intertidal seaweeds after rehydration

Intertidal seaweeds experience periodical desiccation and rehydration to different extents due to the tidal cycles and their vertical distributions. Their photosynthetic recovery process during the rehydration may show different patterns among the seaweeds from different zonations or depths at intertidal zone. In this study 12 species of seaweeds collected from the upper, middle, lower and sublittoral zones were examined. The relationship of the photosynthetic recovery to vertical distribution was assessed by comparing their patterns of photosynthetic and respiratory performances after rehydration following desiccation. Both the photosynthesis and dark respiration declined during emersion, showing certain degrees of recovery after re-immersion into seawater for most species, but the extents were markedly different from one species to the other. The species from upper intertidal zone after being rehydrated for 1 hour, following 2 hours of desiccation, achieved 100 % recovery of their initial physiological activity, while most of the lower or sublittoral species did not achieve full recovery. It is the ability to withstand desiccation stress (fast recovery during rehydration), but not that to avoid desiccation (water retaining ability) that determines the distribution of intertidal seaweeds. Such physiological behavior during rehydration after desiccation reflects the adaptive strategy of intertidal seaweeds against desiccation and their capability of primary production in the process of rehydration

Effects of solar ultraviolet radiation on the photochemical efficiency, photosynthetic pigments and biomass production of Spirulina platensis

Effects of solar ultraviolet radiation (UVR) on Spirulina platensis were studied by investigating its photochemical efficiency, photosynthetic pigments and biomass production while exposed to full spectrum solar radiation or depleted of UVR for understanding how and to what extent UVR influences its photosynthetic physiology and production. It was found that UVR brought about an extra inhibition of photochemical efficiency by 26%-30%. The greatest inhibition of photochemical efficiency in S. platensis was observed at noontime, and then recovered to some extent in late afternoon no matter which treatment they were exposed to. The contents of chlorophyll a, phycocyanin and carotenoids increased during initial stage of the exposure, but decreased with elongated exposure. UVR decreased the biomass yield by about 6%. It indicated that filtering out UVR of solar radiation would raise the productivity of S. platensis, which is an important factor that should be considered in the production

Enhanced calcification ameliorates the negative effects of UV radiation on photosynthesis in the calcifying phytoplankter Emiliania huxleyi

The calcifying phytoplankton species, coccolithophores, have their calcified coccoliths around the cells, however, their physiological roles are still unknown. Here, we hypothesized that the coccoliths may play a certain role in reducing solar UV radiation (UVR, 280-400 nm) and protect the cells from being harmed. Cells of Emiliania huxleyi with different thicknesses of the coccoliths were obtained by culturing them at different levels of dissolved inorganic carbon and their photophysiological responses to UVR were investigated. Although increased dissolved inorganic carbon decreased the specific growth rate, the increased coccolith thickness significantly ameliorated the photoinhibition of PSII photochemical efficiency caused by UVR. Increase by 91% in the coccolith thickness led to 35% increase of the PSII yield and 22% decrease of the photoinhibition of the effective quantum yield (I broken vertical bar(PSII)) by UVR. The coccolith cover reduced more UVA (320-400 nm) than UVB (280-315 nm), leading to less inhibition per energy at the UV-A band.National Basic Research Program of China [2009CB421207]; National Natural Science Foundation of China [40930846, 40676063]; MEL Young Scientist Visiting Fellowship ; Xiamen University and Ph. D. Foundation of Wenzhou Medical College [MELRS0935, 89209008

Photosynthetic responses of Emiliania huxleyi to UV radiation and elevated temperature: roles of calcified coccoliths

Changes in calcification of coccolithophores may affect their photosynthetic responses to both, ultraviolet radiation (UVR, 280-400 nm) and temperature. We operated semi-continuous cultures of Emiliania huxleyi (strain CS-369) at reduced (0.1 mM, LCa) and ambient (10 mM, HCa) Ca(2+) concentrations and, after 148 generations, we exposed cells to six radiation treatments (>280, >295, >305, >320, >350 and >395 nm by using Schott filters) and two temperatures (20 and 25 degrees C) to examine photosynthesis and calcification responses. Overall, our study demonstrated that: (1) decreased calcification resulted in a down regulation of photoprotective mechanisms (i.e., as estimated via non-photochemical quenching, NPQ), pigments contents and photosynthetic carbon fixation; (2) calcification (C) and photosynthesis (P) (as well as their ratio) have different responses related to UVR with cells grown under the high Ca(2+) concentration being more resistant to UVR than those grown under the low Ca(2+) level; (3) elevated temperature increased photosynthesis and calcification of E. huxleyi grown at high Ca(2+) concentrations whereas decreased both processes in low Ca(2+) grown cells. Therefore, a decrease in calcification rates in E. huxleyi is expected to decrease photosynthesis rates, resulting in a negative feedback that further reduces calcification.National Basic Research Program of China [2009CB421207]; program for Changjiang Scholars and Innovative Research Team [IRT0941]; National Natural Science Foundation [40930846, 40876058]; Ministry of Education of Chin

Regulation of gamete release in the economic brown seaweed Hizikia fusiforme (Phaeophyta)

Gamete release is an essential event in artificial seeding of the economic brown seaweed, Hizikia fusiforme. Mass egg release occurred in the dark, with few eggs being discharged in the light. Release of eggs was elicited with eight practical salinity units (one PSU = 1 g sea salts l(-1)) and was inhibited by salinity levels > 32 PSU. Egg release was optimal at 23 degrees C, and was decreased by 72% in agitated seawater compared to unstirred seawater. Inhibitors of photosynthesis and ions channels suppressed egg release, indicating that this process was physiologically associated with photosynthetic activity and ion transport