Fluid flow and sperm guidance: a simulation study of hydrodynamic sperm rheotaxis
Fluid flow and sperm guidance: a simulation study of hydrodynamic sperm rheotaxis
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DOI：
10.1098/rsif.2015.0172
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发表时间：
2015-05-06
影响因子：
3.9
通讯作者：
Gaffney, Eamonn A.
中科院分区：
文献类型：
--
作者：
Ishimoto, Kenta;Gaffney, Eamonn A.
精子是如何找到自己的路的？对引导线索的研究吸引了精子生物学家，尤其是流变性的前景，这是一种引导精子游泳方向的流体流动，已经成为最近广泛研究的主题，很容易受到这种引导可能在哺乳动物雌性生殖道中活跃的前景的激励。例如，有人假设，螺旋形精子鞭毛跳动是这种引导所必需的，然而鞭毛跳动模式有广泛的多样性，例如，在人类细胞中很容易观察到平面形精子跳动。特别是，根据迄今为止提出的流变性的假设机制，这种细胞不会由流体流动引导。在这里，使用模拟方法，我们研究了广泛的鞭毛跳动模式的流变性。假设虚拟精子首先在没有背景流的情况下不具有紧密环绕的轨迹，其次，保持在低剪切区域内以防止被背景流冲走，那么通常可以观察到精子以可能的横向速度游动到流中。在某些过度激活的精子和CatSper突变体中观察到的紧密的精子运动，预计会破坏流变反应，而限制在低剪切区域通常需要边界积累，从而引入了流变行为与鞭毛波形和精子特征之间关系的微妙之处。尽管如此，这样的预测表明这样的流变性指导可能比以前认为的更普遍和健壮，我们记录了与我们的模拟和理解以及迄今为止报道的观察结果一致的流变性存在的简单标准。
How does a sperm find its way? The study of guidance cues has fascinated sperm biologists and in particular the prospect of rheotaxis, that is a fluid flow orienting the direction of sperm swimming, has been the subject of extensive recent study, as readily motivated by the prospect that such guidance may be active in the mammalian female reproductive tract. For instance, it has been hypothesized that helical sperm flagellar beating is necessary for such guidance, whereas there is an extensive diversity of flagellar beating patterns, with planar sperm beating readily observed in human cells for example. In particular, such cells will not be guided by fluid flow according to hypothesized mechanisms for rheotaxis presented thus far. Here, using simulation methods, we investigate rheotaxis for a wide range of flagellar beat patterns. Providing the virtual sperm firstly does not possess a tightly circling trajectory in the absence of a background flow and secondly, remains within a region of low shear to prevent being washed away by the background flow, rheotaxis is generally observed with the sperm swimming into the flow together with a possible transverse velocity. Tight circling sperm motility, as observed in select hyperactivated sperm and CatSper mutants, is predicted to disrupt the rheotactic response, whereas confinement to low shear regions generally requires boundary accumulation, thus introducing subtleties in the relationship between rheotactic behaviours and the flagellar waveform and sperm characteristics. Nonetheless, such predictions suggest such rheotactic guidance may be more common and robust than previously thought, and we document simple criteria for the presence of rheotaxis that are consistent with our simulations and understanding, as well as reported observations to date.