Mating in Chlamydomonas: a system for the study of specific cell adhesion. I. Ultrastructural and electrophoretic analyses of flagellar surface components involved in adhesion

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Abstract

To determine the ultrastructural and biochemical bases for flagellar adhesiveness in the mating reaction in Chlamydomonas, gametic and vegetative flagella and flagellar membranes were studied by use of electron microscope and electrophoretic procedures. Negative staining with uranyl acetate revealed no differences in gametic and vegetative flagellar surfaces; both had flagellar membranes, flagellar sheaths, and similar numbers and distributions of mastigonemes. Freeze cleave procedures suggested that there may be a greater density of intramembranous particles on the B faces of gametic flagellar membranes that on the B faces of vegetative flagellar membranes. Gamone, the adhesive material that gametes release into their medium, was demonstrated, on the basis of ultrastructural and biochemical analyses, to be composed of flagellar surface components, i.e., membrane vesicles and mastigonemes. Comparison of vegetative (nonadhesive) and gametic (adhesive) 'gamones' by use of SDS polyacrylamide gel electrophoresis showed both preparations to be compared of membrane, mastigoneme, and some microtubule proteins, as well as several unidentified protein and carbohydrate staining components. However, there was an additional protein of approximately 70,000 mol wt in gametic gamone which was not present in vegetative gamone. When gametic gamone was separated into a membrane and a mastigoneme fraction on CsCl gradients, only the membrane fraction had isoagglutinating activity; the mastigoneme fraction was inactive, suggesting that mastigonemes are not involved in adhesion.

Original languageEnglish (US)
Pages (from-to)48-69
Number of pages22
JournalJournal of Cell Biology
Volume68
Issue number1
Publication statusPublished - 1976

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ASJC Scopus subject areas

  • Cell Biology

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