2003 Fiscal Year Final Research Report Summary
Mechanism of sperm release and sperm guidance substances in Cycas
| Project/Area Number |
14540616
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生物形態・構造
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| Research Institution | Research Institute for Humanity and Nature (2003)
University of the Ryukyus (2002) |
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Principal Investigator |
TAKASO Tokushiro Research Institute for Humanity and Nature, Research Department, Professor, 研究部, 教授 (50295341)
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| Co-Investigator(Kenkyū-buntansha) |
MIMURA Totsuio Nara Women's University, Faculty of Science, Professor, 理学部, 教授 (20174120)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Cycas / fertilization / gametophyte / gymnosperm / sperm |
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| Research Abstract |
The secretion of pollination drop is known in Cycas as in other gymnosperms. The pollination drop is essential for effective pollen capture. The mechanism of this secretion was examined in this study. The process of fertilization was also examined, and two kinds of liquid secretion at fertilization were also examined from viewpoints of origin and chemical composition. Further, the relationship between the degree of pollination-success and embryo development is examined. The followings are revealed. 1)The pollination drop is secreted throughout pollination period. 2)The pollination drop is secreted from nucellus. 3)The pollination drop contains three kinds of sugars and three kinds of amino acids. 4)Liquid is secreted the surface of the female gametophyte just before fertilization. 5)Sperm swim in this secreted liquid. 6)Another kind of liquid is secreted from neck cells in archegonia at fertilization. 7)Ovules, which failed pollination, do not show subsequent growth. 8)High rate of ovule abortion occurs in ovules which catch less pollen grains.
This study clearly showed that two kinds of secretion occur at fertilization, one form the female gametophyte, the other from archegonia. The secretion from the female gametophyte is known to occur in other gymnosperms, and this secretion might be a universal phenomenon. Further study is needed for the secretion from archegonia. This secretion is likely related to the pollen tube guidance in angiosperms. In addition, the secretion from female gametophyte or archegonia is likely related to sperm guidance in ferns.
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