Molecular Regulation of Light Adaptation and Nitrogen Assimilation in Marine Diatoms.

摘要

The objective of this project was to investigate the molecular and cellular processes that regulate the rate of adaptation of photosynthetic light harvesting and nitrogen assimilation capacity of marine diatoms to fluctuating light and nutrient environments. The initial tasks were to develop and verify nucleic acid and antibody probes for assessing gene presence, transcriptional activity and posttranslational modulation of the expression of nitrate reductase (NR), glutamine synthetase (GS) and the fucoxanthin-chlorophyll a-c pigment-protein (FCP) in diatoms. Given the distinct evolutionary history of diatoms we independently cloned segments of these genes using the polymerase chain reaction and developed antisera specific to the diatom forms of these enzymes. Sequence analysis indicates that NR and GS in diatoms exhibit limited homology with the forms occurring in land plants. Concurrent application of the NR nucleic acid probe and antisera indicated that the expression of NR is under strong transcriptional and post translational control when cells are exposed to realistic environmental shifts. NR and FCP were observed to be inversely regulated by shifts in light availability.