Changes in protein profile and aminoacids in Cladophora vagahunda (L.) Hoek (Chlorphyta) in response to salinity stress
2006
Vaishnav, S.D.N.B., College for Women, Chromepet, Chennai 600 044 (India)
Marine organisms have evolved various osmoregulatory mechanisms to tolerate a wide range of salinity. Cladophora vagabunda (L.) Hoek acclimatize to a wide range of salinity and occurs even in intertidal pools with waters of high salinity. The adjustment of intracellular solute concentration in response to salinity variation is regarded as the fundamental aspect of salinity tolerance. Therefore, C. vagabunda was grown at various salinities, and its amino acid composition, shift in protein bands and glycine betaine were determined. Amino acids are important osmoregulatory metabolites in algae hence the amino acid composition was estimated by HPLC. Among the amino acid pool, the acidic amino acids viz., aspartate and glutamate and basic amino acids, viz., lysine, histidine and arginine showed increased concomitant to increases in salinity. Proline was present only in hypersalinity. Protein plays a significant role as osmoregulatory substance in the form of enzymes, tertiary sulphonium compound and membrane protein. Electrophoretic protein profile of C. vagabunda grown at varying salinity was obtained by SDS-PAGE. The alga grown in 10% o (hyposalinity) showed only 12 protein bands, in 34% o salinity (control) it revealed 13 polypeptide bands and twenty protein bands were observed in the alga grown under hypersalinity (65% o), with a wide range of low to high molecular weight, Sup 1H NMR studies showed that glycine betaine also respond to changing salinity. Thus, the present study shows that certain amino acids, proteins and glycine betaine act as osmoticants.
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