Abstract:

In order to learn the ways and possible utilization mechanisms of dissolved inorganic carbon (DIC) in marine phytoplankton species under carbon replete or limited conditions, the activity of extracellular carbonic anhydrase (CA) was assayed in different pH, CO2 and DIC concentrations. Extracellular CA in Amphidinium carterae and Prorocentrum minimum was detected under carbon replete conditions, while in Melosira sp., Phaeodactylum tricornutum, Skeletonema costatum, Thalassiosira rotula, Emiliania huxleyi and Pleurochrysis carterae, CA activity was assayed under conditions of carbon limitation. No CA activity was found even under carbon limited conditions in Chaetoceros compressus, Glenodinium foliaceum, Coccolithus pelagicus, Gephrocapsa oceanica and Heterosigma akashiwo. In species without extracellular CA activity, the direct HCO3- uptake was investigated using a pH drift technique and the anion exchange inhibitor 4′4′diisothiocyanatostilbene 2,2 disulfonic acid (DIDS) in a closed system. The result showed that direct HCO3- transport might occur by an anion exchange mechanism in species Coc. pelagicus and G. oceanica. Of the 13 species investigated, only H. akashiwo did not have the potential for direct uptake or extracellular CA catalyzed HCO3- utilization.

海洋浮游藻类无机碳利用机理的研究

缪晓玲^1,2  吴庆余^1*

(1.清华大学生物科学与技术系,北京,100084；2.福建宁德师范高等专科学校生物系,福建宁德,352100)

为了认识海洋浮游藻类在碳充足和碳受限条件下对水体中溶解无机碳(DIC)的利用方式与可能机理,对13种海洋浮游藻类在不同pH和CO2浓度及不同DIC条件下细胞外碳酸酐酶(CA)的活性进行了分析测定.结果显示:13种藻中,只有Amphidinium carterae和Prorocentrum minimum在碳充足条件下具细胞外CA活性.Melosira sp.、Phaeodactylum tricornutum、Skeletonema costatum、Thalassiosira rotula、Emiliania huxleyi和Pleurochrysis carterae则在碳受限条件下才具细胞外CA活性.Chaetoceros compressus、Glenodinium foliaceum、Coccolithus pelagicus、 Gephrocapsa oceanica和Heterosigma akashiwo即使在碳受限条件下也未检测到细胞外CA活性.应用封闭系统中pH漂移技术和阴离子交换抑制剂4′4′-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS)等的研究表明,Coc. pelagicus和G. oceanica可通过阴离子交换机制进行HCO-3的直接利用.H. akashiwo没有潜在的HCO-3直接利用或细胞外CA催化的HCO-3利用.

关键词 溶解无机碳 (DIC) 细胞外碳酸酐酶

*通讯作者 Email: qingyu@tsinghua.edu.cn

Key words: dissolved inorganic carbon (DIC), extracellular carbonic anhydrase (CA), 4′4′diisothiocyanatostilbene 2,2 disulfonic acid (DIDS), dextran bound sulfonamide (DBS)