PUB - Publikationen an der Universität Bielefeld

Protein synthesis of the halotolerant green alga Dunaliella parva adapted to 0.75 and 1.5 M NaCl was compared with synthesis following a hyper- or hypoosmotic salt stress by using S-35-protein-labelling and one- and two-dimensional polyacrylamide gel electrophoresis. Changes in salinity induced four types of modifications: Transient and permanent intensifications of proteins, and transient and permanent decreases. The majority of modifications occurred only during the first hours after the osmotic shock; both hyper- and hypoosmotic stress induced a number of analogous changes in protein synthesis. A few of these modifications could be still detected after long-term adaptation to the two different salt concentrations. Prominent differences were found, e.g. in proteins of 36 and 170 kDa, typically expressed in algae adapted to 1.5 M NaCl; these polypeptides were absent or synthesized at very low rates in cells of 0.75 M NaCl. Proteins of, e.g., 23, 24.5, and 37.5 kDa showed their highest rate of expression in the low salt algae.