1991 Fiscal Year Final Research Report Summary
Cytoskeletal studies of peculiar mitoses during male gametogenesis of angiosperms using immunofluorescence methods.
Project/Area Number |
01540583
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Research Category |
Grant-in-Aid for General Scientific Research (C)
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Allocation Type | Single-year Grants |
Research Field |
植物形態・分類学
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Research Institution | Jikei University School of Medicine |
Principal Investigator |
TERASAKA Osamu Jikei University School of Medicine, The Medical Department, Lecturer, 医学部, 講師 (80110930)
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Project Period (FY) |
1989 – 1991
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Keywords | Actin / Generative Cell / Immunofluorescence / Microtubule / Myosin / Nuclear Migration / Pollen / Vegetative Cell |
Research Abstract |
During the male gametogenesis of anglospenns, some peculiar events concerning cell division and differentiation successively occur ; nuclear migration in microspore cell, unequal division of microspore, differentiation between generative and vegetative cells and generative cell division in pollen tube. The associations of microtubules (Ws), actin and myosin with these events were studied using immlmofluo-rescence methods and inhibitory experiments. In Tradescantia paludosa, microspore nuclei migrated twice before the division. The second nuclear migration, essential to the unequal division, was dependent on Nffs, but the first was independent. MTs constructed asymmetric mitotic spindle and phragmoplast in microspore division. MTs mediated generative cell elongation but not pollen tube elongation. The spindles in generative cell divisions of Calanthe and some other species were peculiar configurations in which metaphase chromosomes lay in tandem along the spindle axis and sister chromos
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omes separated anti-parallelly by spindle elongation during anaphase. No F-actin associating with the nuclear migrations or unequal division was found in microspores. Distinct F-actin was found only in the phragmoplast. F-actin was organized on both transverse sides of the vegetative nucleus after microspore division, and developed into an abundant complex network in mature pollen grains. This F-actin played an important role in pollen tube growth or cytoplasmic streaming, but not in generative cell division. In conclusion, the different dynamics between MTs and actin during male gametogenesis were examined. Myosin was detected on the surface of generative cells and vegetative cell organelles of T. virginiana and two other species. The migration of these and of vegetative nuclei within pollen tubes, as well as tube growth, were inhibited by N-ethylmaleimide, an inhibitor of actomyosin ATPase activity. Indications were that the force for their migration was produced by an actomyosin system, although further research is underway on the subject of whether or not myosin is present in vegetative nuclei. Less
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Research Products
(12 results)