EFFECTS OF NITROGEN AND PHOSPHORUS STARVATION ON NUCLEIC-ACID AND PROTEIN-CONTENT OF HETEROCAPSA SP

Changes in the protein, RNA and DNA content related to nitrogen (N) an d phosphorus (P) starvation were studied in the marine dinoflagellate Heterocapsa sp. grown in batch cultures. In both cases of nutrient sta rvation, metabolic adaptations affected protein and RNA pools, while t he DNA content per cell remained approximately constant. N starvation led to a parallel decrease in protein and RNA concentration which caus ed the protein/RNA ratios to remain constant. A dramatic decrease in t he RNA content characterized the P-starved cultures, although protein synthesis continued. The ribosomal RNA content was lower than expected given the continuation of protein synthesis. It is suggested that pro tein/RNA ratios could be used as an indicator of P starvation, while p rotein/chlorophyll ratios would characterize N starvation.