| Project/Area Number |
16K14775
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Animal physiology/Animal behavior
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| Research Institution | Shimane University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
岩田 容子 東京大学, 大気海洋研究所, 特別研究員(移行) (60431342)
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| Project Period (FY) |
2016-04-01 – 2018-03-31
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| Project Status |
Completed (Fiscal Year 2017)
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| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Keywords | 精子 / プロトン勾配 / センシング / 鞭毛 / 走化性 / pHイメージング / 受精 / 頭足類 / プロトンセンシング / 精子走化性 / 雄二型 / 生殖戦略 / 受精様式 / 鞭毛運動 / サワーセンシング / 代替繁殖戦術 |
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| Outline of Final Research Achievements |
Here, we show that initiation of the turn motion requires a swim down a steep proton gradient (a theoretical estimation of more than 0.025 pH/s), crossing a threshold pH value of ~5.5. Time-resolved kinematic analysis revealed that the turn sequence results from the rhythmic exercise of two flagellar motions: a stereotypical flagellar ‘bent-cane’ shape followed by asymmetric wave propagation, which enables a sharp turn in the realm of low Reynolds numbers. This turning episode is terminated by an ‘overshoot’ trajectory that differs from either straight-line motility or turning. As with bidirectional pH-taxes in some bacteria, squid spermatozoa also showed repulsion from strong acid conditions with similar flagellar kinematics as in positive pH-taxis. These findings indicate that squid spermatozoa might have a unique reorientation mechanism, which could be dissimilar to that of classical egg-guided sperm chemotaxis in other marine invertebrates.
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