Mucilage secretion regulated by sex pheromones in Closterium peracerosum-strigosum-littorale [Chlorophyceae] complex
2003
Akatsuka, S. (Toyo Univ., Itakura, Gunma (Japan). Faculty of Life Sciences) | Sekimoto, H. | Iwai, H. | FUkumoto, R. | Fujii, T.
When mating-type plus (mt sup(+)) and minus (mt sup(-)) cells of the Closterium peracerosum-strigosum-littorale complex were mixed in nitrogen-depleted mating medium, secretion of mucilage containing uronic acid from cells was markedly activated and the mucilage accumulated around the cells. Substances with the ability to stimulate mucilage secretion from mt sup(+) and mt sup(-) cells were detected in media in which mt sup(-) and mt sup(+) cells had been separately cultured, respectively, We designated the active substances secreted from mt sup(+) and mt sup(-) cells mucilage secretion-stimulating pheromone (MS-SP)-plus and MS-SP-minus, respectively, Activity of MS-SP-plus and MS-SP-minus decreased to 20% level by incubation at 80 deg C for 10 min. Light was indispensable for the secretion of mucilage. The secretion of MS-SP-plus and MS-SP-minus decreased with dark treatment. MS-SP-plus eluted at around 95 k from a gel filtration column, and reacted with antibodies against two subunits of protoplast-release-inducing protein (PR-IP), which induces protoplast release from mt sup(-) cells. MS-SP-minus eluted at around 20 k from a gel filtration column, and reacted with an antibody against the PR-IP inducer, which induces the secretion of PR-IP from mt sup(+) cells. In addition, purified PRIP and PR-IP inducer stimulated mucilage secretion from mt sup(-) and mt sup(+) cells, respectively. These results strongly suggested that MS-SP-plus and MS-SP-minus were the same molecules as the PR-IP and the PR-IP inducer, respectively.
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