CO2 and HCO3- uptake in marine diatoms acclimated to different CO2 concentrations
CO2 and HCO3- uptake in marine diatoms acclimated to different CO2 concentrations
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DOI：
10.4319/lo.2001.46.6.1378
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发表时间：
2001-09-01
影响因子：
4.5
通讯作者：
S端ltemeyer, D
中科院分区：
文献类型：
--
作者：
Burkhardt, S;Amoroso, G;S端ltemeyer, D
在稳态光合作用过程中的CO2和HCO 3-的细胞吸收率测定海洋硅藻Thalassiosira weissflopolyum和Phaeodactylum tricornutum，适应CO2分压为36，180，360，和1,800 ppmv。此外，在体内活性的细胞外（eCA）和细胞内（伊卡）碳酸酐酶测定与CO2的可用性。这两个物种响应减少CO2供应的eCA和伊卡活动的增加。在三角褐指藻中，eCA活性在较高CO2浓度下接近检测限。同时吸收CO2和HCO 3-中观察到的两种硅藻。在空气平衡CO2水平（360 ppmv）下，T.三角褐指藻吸收CO2和HCO 3-的速率大致相同，而三角褐指藻吸收CO2的速率是HCO 3-的两倍。在这两种硅藻中，CO2和HCO 3-吸收率随着CO2浓度的降低而逐渐降低，而CO2和HCO 3-的底物亲和力随着CO2浓度的降低而降低。摄取量增加。半饱和浓度始终小于或等于5 μ M的CO2的CO2吸收和< 700 μ M的HCO 3-的HCO 3-的吸收，我们的研究结果表明，在海洋表面沃茨的浓度通常遇到的两种硅藻的CO2和HCO 3-的高效吸收系统的存在和调整吸收速率的能力，以广泛的无机碳供应。
Rates of cellular uptake of CO2 and HCO3- during steady-state photosynthesis were measured in the marine diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, acclimated to CO2 partial pressures of 36, 180, 360, and 1,800 ppmv. In addition, in vivo activity of extracellular (eCA) and intracellular (iCA) carbonic anhydrase was determined in relation to CO2 availability. Both species responded to diminishing CO2 supply with an increase in eCA and iCA activity. In P. tricornutum, eCA activity was close to the detection limit at higher CO2 concentrations. Simultaneous uptake of CO2 and HCO3- was observed in both diatoms. At air-equilibrated CO2 levels (360 ppmv), T. weissflogii took up CO2 and HCO3- at approximately the same rate, whereas CO2 uptake exceeded HCO3- uptake by a factor of two in P. tricornutum. In both diatoms, CO2 and HCO3- uptake ratios progressively decreased with decreasing CO, concentration, whereas substrate affinities of CO, and HCO.- uptake increased. Half-saturation concentrations were always less than or equal to5 muM CO2 for CO2 uptake and < 700 muM HCO3- for HCO3- uptake, Our results indicate the presence of highly efficient uptake systems for CO2 and HCO3- in both diatoms at concentrations typically encountered in ocean surface waters and the ability to adjust uptake rates to a wide range of inorganic carbon supply.