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Membrane recycling and calcium dynamics during settlement and adhesion of zoospores of the green alga Ulva linza
Author(s) -
THOMPSON S. E. M.,
CALLOW J. A.,
CALLOW M. E.,
WHEELER G. L.,
TAYLOR A. R.,
BROWNLEE C.
Publication year - 2007
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2007.01661.x
Subject(s) - exocytosis , biophysics , zoospore , membrane , endosome , cytoplasm , endocytosis , cytosol , calcium , chemistry , biology , microbiology and biotechnology , biochemistry , botany , intracellular , cell , enzyme , spore , organic chemistry
Recruitment of individuals of the marine alga Ulva linza on to a suitable habitat involves the settlement of motile zoospores on to a substratum during which a preformed adhesive is secreted by vesicular exocytosis. The fluorescent styryl dye FM 1‐43 and fluorescent Ca 2+ indicators were used to follow membrane cycling and changes in cytosolic Ca 2+ ([Ca 2+ ] cyt ) associated with settlement. When swimming zoospores were exposed continuously to FM 1‐43, the plasma membrane was preferentially labelled. During settlement, FM 1‐43‐labelled plasma membrane was rapidly internalized reflecting high membrane turnover. The internalized membrane was focused into a discrete region indicating targeting of membrane to an endosome‐like compartment. Acetoxymethyl (AM)‐ester derivatives were found to be unsuitable for monitoring [Ca 2+ ] cyt because the dyes were rapidly sequestered from the cytoplasm into sub‐cellular compartments. [Ca 2+ ] cyt was, however, reliably measured using dextran‐conjugated calcium indicators delivered into cells using a biolistic technique. Cells loaded with Oregon Green BAPTA‐1 dextran (Invitrogen, Paisley, UK) showed diffuse cytosolic loading and reliably responded to imposed changes in [Ca 2+ ] cyt . During settlement, zoospores exhibited both localized and diffuse increases in [Ca 2+ ] cyt implying a role for [Ca 2+ ] cyt in exocytosis of the adhesive.