Gametic behavior in a marine green alga, Monostroma angicava: an effect of phototaxis on mating efficiency
Gametic behavior in a marine green alga, Monostroma angicava: an effect of phototaxis on mating efficiency
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海洋绿藻 Monostroma angicava 的配子行为：趋光性对交配效率的影响
DOI：
10.1007/s004970050187
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发表时间：
1999
影响因子：
--
通讯作者：
P. Cox
中科院分区：
文献类型：
--
作者：
T. Togashi;T. Motomura;T. Ichimura;P. Cox
抽象的。在轻微异配海洋绿藻 Monostroma angicava Kjellman 中对配子趋光行为的作用进行了实验测试，发现了趋光性对交配效率的影响。雄性和雌性配子均对白光源表现出正趋光性。相反，它们对红色光源没有反应。它们的游泳速度在这两种照明光源之间没有差异。因此，有人认为配子本身的搜索能力在趋光性和非趋光性条件下可能没有变化。交配过程中形成的受精卵的数量可以表示为雄性配子和雌性配子之间的相遇次数与导致性融合的相遇分数的乘积。在这项研究中，试管中混合高密度的雄性和雌性配子，几乎所有次要（数量较少）的配子在 10 分钟内发生性融合。将配子悬浮液稀释一半后，上方白光照射的试管中的交配效率高于黑暗对照中的交配效率。这表明雄性和雌性配子通过其正趋光性聚集在水面，从而增加了相遇率。如果试管从上方被白光照射并摇动，交配效率也会降低。由于在平合子中清楚地显示出负趋光性，因此我们认为M. angicava中雄性和雌性配子的正趋光性是增加配子相遇率的适应性特征，而不是像之前报道的一些海藻游动孢子那样用于受精卵的分散。
Abstract. The role of phototactic behavior of gametes was tested experimentally in the slightly anisogamous marine green alga Monostroma angicava Kjellman, and the effect of phototaxis on mating efficiency was discovered. Both male and female gametes showed positive phototaxis in response to a white light source. In contrast, they did not respond to a red light source. Their swimming velocity did not differ between these two illuminating light sources. It was, therefore, suggested that the search ability of the gamete itself might not vary between phototactic and non-phototactic conditions. The number of zygotes formed during the mating process may be expressed as the product of the number of encounters between male and female gametes and the fraction of encounters that result in sexual fusion. In this study, with high densities of male and female gametes mixed in test tubes, almost all minor (fewer in number) gametes fused sexually within 10 min. After dilution of the gamete suspensions by half, mating efficiency in test tubes illuminated by white light from above was higher than that in dark controls. This suggests that male and female gametes gathered at the water surface through their positive phototaxis, thus increasing the rate of encounters. Mating efficiency also decreased if the test tubes were illuminated from above by white light and also shaken. Since negative phototaxis is clearly shown in planozygotes, we suggest that positive phototaxis of male and female gametes in M. angicava is an adaptive trait for increasing the rate of gametic encounters rather than for the dispersal of zygotes as previously reported for zoospores of some marine algae.