Photosynthetic characteristics and organization of chlorophyll in marine dinoflagellates

Abstract

The photosystem I reaction center complex, the P -700-chlorophyll a -protein, has been isolated from the photosynthetic membranes of two marine dinoflagellates, Gonyaulax polyedra and Glenodinium sp., by detergent solubilization with Triton X-100. The complexes isolated from the two species were indistinguishable, exhibiting identical absorption properties (400-700 nm) at both room (300 K) and low (77 K) temperature. The room temperature, red wavelength maximum was at 675 nm. The absorption properties, kinetics of photobleaching, sodium dodecyl sulfate electrophoretic mobilities, and chlorophyll a/P -700 ratio (50 ± 10) of the P -700-chlorophyll a -protein complexes from the two species also were essentially the same and similar to those properties characterizing P -700-chlorophyll a -protein complexes of higher plants and green algae. Photosynthetic unit sizes were determined for cells grown at 1000 μW/cm 2 . Both dinoflagellates had unit sizes (total chlorophyll/ P -700 ratios) of about 600, even though the distribution of chlorophyll a , chlorophyll c , and peridinin in the light-harvesting components differed in Gonyaulax and Glenodinium . The number of photosynthetic units per cell in the two species correlates directly with their photosynthetic activities. A model is presented for the distribution of chlorophyll in the photosynthetic apparatus of these dinoflagellates which accounts for the known role of the isolated pigment-protein complexes and for the known photoadaptive physiology in pigmentation and photosynthesis for these species.

Light—Shade Adaptation

“…Previous studies from our laboratory (19,21) and that of Grumbach et al (9) (4), however, it has been suggested that chang,es in the characteristics of PSU are associated with changes in piiotosynthetic response (3,5,11,20).…”

Development, morphological characteristics and viability of temporary cysts ofPyrodinium bahamensevar.compressum(Dinophyceae)in vitro

“…Dinoflagellates contain a single type of chl c which serves as the accessory pigment to the chl a-protein complex, common in dinoflagellates as the peridinin (Boczar & Prézelin, 1987) but has not yet been investigated in Pyrodinium. In Gonyaulax and Glenodinium, chls a and c occur in a molar ratio of 4 : 1 (Prézelin & Alberte, 1978) while in Pyrodinium, it occurs in a ratio of~5 : 1 (ng cell −1 ) for both vegetative cells grown in f/2 medium and low total nutrient. The absence of chl b in either stage of the dinoflagellate corroborates the findings of Strain et al (1943) who claimed that it was not observed in majority of marine plants with chl c.…”

Acclimation and adaptation to irradiance in symbiotic dinoflagellates. I. Responses of the photosynthetic unit to changes in photon flux density

“…The evidence presented PSU characteristics have been determined. Prezelin & here indicates that the 3 species of Symbiodinium ana- Alberte (1978) reported chl a-based PSU-P,,, sizes of lyzed effectively modify their photosynthetic machin-600 for the free-living dinoflagellates Glenodinium sp. ery in response to changes in photon flux density.…”