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PROTEINS IMMUNOLOGICALLY RELATED TO DEHYDRINS IN FUCOID ALGAE
Author(s) -
Li Rui,
Brawley Susan H.,
Close Timothy J.
Publication year - 1998
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.1998.340642.x
Subject(s) - biology , fucus vesiculosus , desiccation , algae , intertidal zone , botany , embryo , ecology , microbiology and biotechnology
Adult fucoid algae on Atlantic shores have well‐characterized, species‐specific tolerances to the varying levels of desiccation that occur from the low to high intertidal zones; however, less is known about embryonic tolerances and their mechanistic basis. We investigated this by 1) exposing embryos of Fucus evanescens C. Agardh, F. spiralis L., and F. vesiculosus L. from the Maine shore to osmotic desiccation in hypersaline seawater and 2) examining whether these embryos contain species‐specific dehydrins, proteins first identified in higher plants that are hypothesized to confer tolerance to dehydration. Embryonic survival when cultured in hypersaline seawater >100 practical salinity units (psu) correlated with the position of these species in the intertidal zone ( F. spiralis > F. vesiculosus > F. evanescens ), but all 1‐day‐old embryos of these species tolerated treatment with 100 psu or lower seawater. Proteins (17–105 kDa) immunologically related to dehydrins were detected on western blots with dehydrin antibodies raised against a synthetic peptide representing the conserved motif of dehydrins in higher plants. These proteins were constitutive and unstable when subjected to prolonged (>15 min) temperatures above 55° C, unlike most higher plant dehydrins, which are inducible and remain soluble at 75°–100° C. The presence of these proteins was species‐ and stage‐specific. Sperm of F. vesiculosus had a characteristic protein of 76 kDa, whereas eggs and embryos (6 h to 3 days old) had a 92‐kDa protein. By 1 week of age, expression of the 92‐kDa protein decreased, and the 35‐kDa protein of adults was present. Embryos of A. nodosum L. and Pelvetia compressa J. Agardh DeToni contained an 85‐kDa protein rather than the 92‐kDa protein of Fucus embryos ( F. distichus L., F. evanescens, F. spiralis, and F. vesiculosus ). The 92‐kDa protein became more abundant in embryos exposed to hyperosmotic seawater at 50 psu ( F. evanescens and F. vesiculosus ) or 150 psu ( F. spiralis ); however, dehydrin‐like proteins of some molecular masses decreased in abundance simultaneously. Further characterization of these proteins is required to establish whether they protect embryos against intertidal desiccation.