Phytophthora capsiciの遊走子嚢における遊走子放出の原動力としての微小管の関与

Miyata, Yoshio

The motive forces of the indirect germination (the zoospore release from the zoosporangium) in Phytophthora is commonly explained by the turgor pressure generated in the sporangial cell. One of the most powerful evidences for this hypothesis is the perfect supression of the germination in the hypertonic solutions of some carbohydrates, such as glucose, fructose, saccharose and so on. But there were a few phenomena not to be easily explained by the hypothesis under the optical microscopic observations. For example, the small particles remained in the sporangial cell were continuously discharged after the indirect germination of the zoosporangium. As another mechanisms were presumed to operate in the zoospore release from the sporangium, several experiments were carried out in the physiological and morphological manners. Several results obtained against the turgor pressure are as follows : (1). Zoospores were fairly able to release in the hypertonic solutions of the non-or hardly metabolizable carbohydrates, such as mannitol, sorbitol, 2-deoxy-glucose and so on. (2). Aditionally, the experiments with the metabolic inhibitors, such as actinomycin D (a mRNA synthetic inhibitor), cycloheximide (a protein synthetic one), antimycin, origomycin, 2,4-DNP (respiratory ones) suggested that the activation of the cell metabolism with the new mRNA-dependent protein synthesis and the high ATP consumption, was necessary to the zoospore release from the sporangium. (3). Binblastin (a microtubule inhibitor, 100μg/ml) inhibited perfectly the zoospore release from the zoosporangium. (4). Microtubule-like structures and their bundles were also observed in the lateral cleavages (the sections between the inner surface of the cell wall and the cytoplast of the sporangium) by the electron microscopy. (5). The fluorescent light was detected around the zoospore clod and the inner surface of the sporangial wall by the fluorescent-antibody technique. The tubulin fractions of the PMSG buffer soluble proteins of pig brain were used as the antigens. The existence of the microtubule or the related structures was probably indicated at the fluolescent positions. The results possibly suggest that the mechanochemical forces of the microtubule systems is concerned to the zoospore release from the sporangium of this fungus.

Phytophthora capsiciの遊走子嚢における遊走子放出の原動力としての微小管の関与

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