Divinyl chlorophyll a in the marine eukaryotic protist Alexandrium ostenfeldii (Dinophyceae)

16 páginas, 4 tablas, 7 figuras

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, 14C 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

This work was partially funded by the culture collection of harmful microalgae of IEO (CCVIEO). J.L.G. acknowledges financial support from Xunta de Galicia (project PGIDT02RMA40202PR). Funding was also provided by the Academy of Finland (grant # 128833 to A.K.

Peer reviewed