Variations in biochemical parameters of Heterocapsa sp. and Olisthodiscus luteus grown in 12:12 light:dark cycles II. Changes in pigment composition

Institut Ciències del Mar
Hydrobiologia (Impact Factor: 1.99). 07/1992; 238(1):149-157. DOI: 10.1007/BF00048783

ABSTRACT Photosynthetic pigment composition was studied in batch cultures of Heterocapsa sp. and Olisthodiscus luteus growing exponentially in a 12:12 light:dark cycle. Both species divided in the dark. The synthesis of pigments was continuous for both species. However for chlorophyll c and peridinin, in Heterocapsa sp., and chlorophyll c and fucoxanthin, in O. luteus, (pigments belonging to light harvesting complexes) the synthesis was significantly higher during the light period. Concentrations per total cell volume (TCV) of chlorophyll a, chlorophyll c, peridinin and diadinoxanthin in Heterocapsa sp., and chlorophyll a, chlorophyll c, fucoxanthin and violaxanthin in O. luteus, showed a maximum at the onset of light and decreased during the light period. The values of the chlorophyll a:chlorophyll c, chlorophyll a:peridinin and chlorophyll a:fucoxanthin ratios are compared with data reported in the literature.

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    ABSTRACT: The division cycle of two phytoplankton species, Olisthodiscus luteus and Heterocapsa sp. was studied in relation to a 12:12 light:dark cycle. Batch cultures in exponential phase were sampled every three hours during 48 hours. Cell number, cellular volume and DNA and RNA concentrations were measured. Microscopic observations of the nuclei of Heterocapsa sp. were also performed. In both species, cell division took place in the dark. In Heterocapsa sp., DNA and RNA showed a similar diel variability pattern, with synthesis starting at the end of the light period, previously to mitosis and cytokinesis. In O. luteus. Major RNA synthesis occurred during darkness, and DNA was produced almost continuously. Both species presented different values and diel rhythmicity on the RNA/DNA ratios.
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    Hydrobiologia 09/1996; 333(2):87-94. · 1.99 Impact Factor

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