Rodríguez Francisco, Garrido José Luis, Sobrino Cristina, Johnsen Geir, Riobó Pilar, Franco José, Aamot Inga, Ramilo Isabel, Sanz Noelia, Kremp Anke
Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Spain.
Instituto de Investigaciones Marinas (CSIC), Vigo, Spain.
Environ Microbiol. 2016 Feb;18(2):627-43. doi: 10.1111/1462-2920.13042. Epub 2015 Dec 2.
Here it is reported the first detection of DV-chl a together with the usual chl a in the marine dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Growth response and photosynthetic parameters were examined at two irradiances (80 and 240 μmol photons m(-2) s(-1)) and temperatures (15 °C and 19 °C) in a divinylic strain (AOTV-OS20) versus a monovinylic one (AOTV-OS16), using in vivo chl a fluorescence kinetics of PSII to characterize photosynthetic parameters by pulse amplitude modulated fluorescence, (14)C assimilation rates and toxin analyses. The divinylic isolate exhibited slower growth and stronger sensitivity to high irradiance than normal chl a strain. DV-chl a : chl a ratios decreased along time (from 11.3 to < 0.5 after 10 months) and to restore them sub-cloning and selection of strains with highest DV-chl a content was required. A mutation and/or epigenetic changes in the expression of divinyl reductase gene/s in A. ostenfeldii may explain this altered pigment composition. Despite quite severe limitations (reduced fitness and gradual loss of DV-chl a content), the DV-chl a-containing line in A. ostenfeldii could provide a model organism in photosynthetic studies related with chl biosynthesis and evolution.
本文报道了在波罗的海的海洋甲藻亚历山大藻（Alexandrium ostenfeldii）中首次检测到二乙烯基叶绿素a（DV-chl a）以及常见的叶绿素a。在两种辐照度（80和240 μmol光子·m⁻²·s⁻¹）和温度（15℃和19℃）条件下，对一个二乙烯基菌株（AOTV-OS20）和一个单乙烯基菌株（AOTV-OS16）的生长响应和光合参数进行了研究，利用PSII的活体叶绿素a荧光动力学，通过脉冲幅度调制荧光、¹⁴C同化率和毒素分析来表征光合参数。与正常叶绿素a菌株相比，二乙烯基分离株生长较慢，对高辐照度更敏感。DV-chl a与叶绿素a的比值随时间下降（10个月后从11.3降至<0.5），需要通过亚克隆和选择DV-chl a含量最高的菌株来恢复该比值。亚历山大藻中二乙烯基还原酶基因表达的突变和/或表观遗传变化可能解释了这种色素组成的改变。尽管存在相当严重的局限性（适应性降低和DV-chl a含量逐渐丧失），但亚历山大藻中含DV-chl a的品系可为与叶绿素生物合成和进化相关的光合研究提供一种模式生物。
