Genotypic temperature adaptations of cellular functions and proteins in two Zostera species

The thermostability of protoplasmic streaming, the capacity for plasmolysis and reduction of tetrazolium salt, and the thermostability of acid phosphatase and peroxidase were compared in two species of Zostera, Z. marina L. and Z. noltii Hornem. which were growing in Sevastopal Bay on the Black Sea. The thermostability of studied functions and enzymes in Z. noltii is approximately 4° or 5° C higher than that in Z. marina and this is consistent with the greater thermophily of Z. noltii, which has a more southerly habitat and which is a less deep-water form than Z. marina. The adaptive significance of the correlation between function and protein thermostability and the environmental temperature is regarded as the adjustment of the level of protein flexibility to a prevailing ambient temperature.