1987 Fiscal Year Final Research Report Summary
Studies on the Mechanism Controlling Periodicity in Cytoplasmic Streamings
| Project/Area Number |
61480476
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
分子遺伝学・分子生理学
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| Research Institution | Osaka University |
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Principal Investigator |
KURODA Kiyoko Faculty of Science, Osaka University; Associate Professor, 理学部, 助教授 (30028138)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Periodicity / Cytoplasmic streaming / Amoeboid movement / Physarum plasmodium / Caffeine drop / Ca^<++> / Contraction-relaxation / アクトミオシン繊維束 |
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| Research Abstract |
Plasmodial fragments of Physarum polycephalum contracted-relaxed cyclicly with a period of 3-5 min. By both polarized light and fluorescence microscopy, the organization and distribution of the cytoplasmic actomyosin fibrils in the fragments changed in synchrony with the contraction cycle. The fibrils formed during the contraction phase. During relaxation, the fibrils degenerated and disappeared almost completely. The results obtained by fluometry of the fragments stained with rhodamin phalloidin, suggested that the G-F transformation of actin is not the main underlying process of the fibrillar formation. Sperical endoplasmic drop obtained by treatment of Physarum plasmodium with caffeine show a vigorous movement. Majority of the luminescence of aequorin microinjected in a caffeine drop was localized at the basal region of the moving granular endoplasm. Local solation mediated by a high Ca^<++> concentration regulates the movement of endoplasm in the caffeine drop.
In glycerinated model
… More
of Amoeba proteus, on addition of Mg-ATP in 10^<-4> M Ca^<++>, the filament aggregates disappeared, and few thin filaments were observed in the cytoplasm 10 min after the reactivation. Actin and profilin were purified from Amoeba proteus. Apparent molecular weights were 44,000 and 12,000 respectively. Amoeba G-actin was phosporylated in a Ca^<++>-dependent manner with a kinase. When Amoeba profilin was added, more than 80% of the actin was phosphorylated and did not polymerize in this solution. We meawured the aequorin luminescence from a single aequorin-injected Amoeba proteus. Luminescence intensity was higher in the posterior than the anterior region. In an actively locomoting amoeba, the transient and strong luminescence appeared at intervals of several minutes in several places, especially at loci where the moving directions were reversing. The Ca^<++> concentration in these areas was estimated to be on the order of 10^<-5> M. Thus, local solation mediated by high Ca^<++> concentration may regulated amoeboid movement. Less
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