Ford W C L
Department of Clinical Science at South Bristol, St Michael's Hospital, University of Bristol, Bristol, UK.
Hum Reprod Update. 2006 May-Jun;12(3):269-74. doi: 10.1093/humupd/dmi053. Epub 2006 Jan 11.
It is doubtful that diffusion can deliver sufficient ATP from the mitochondria to sustain activity at the distal end of the sperm flagellum. Glycolytic enzymes bound to the fibrous sheath could provide energy along the flagellum at the point it is required. An obligatory role for glycolysis is supported by the lack of progressive motility in sperm from mice where the gene for sperm-specific glyceraldehyde-3-phosphate dehydrogenase (GAPDHs) had been 'knocked out'. Here, I review some evidence against this idea. First, pure diffusion from the mitochondrion is likely to be adequate in species with smaller sperm, and it is possible that rapid ATP delivery required in larger sperm could be achieved by an adenylate kinase shuttle. Second, experience with alpha-chlorohydrin demonstrates that sperm can remain motile with normal ATP concentrations despite inhibition of GAPDHs; adverse effects only occur if glucose is added and high levels of glycolytic intermediates accumulate. These observations undermine the GAPDHs knockout mouse as evidence for an essential role of local glycolysis. Third, sperm from many species can remain motile for long periods in sugar-free media and excepting dog sperm, evidence that gluconeogenesis is a possible explanation, is weak. In most species, it is unlikely that local glycolysis is the only way that ATP can be supplied to the distal flagellum.
扩散作用能否将足够的三磷酸腺苷（ATP）从线粒体传递到精子鞭毛的远端以维持其活性，这一点尚存在疑问。与纤维鞘结合的糖酵解酶可以在鞭毛所需的部位提供能量。精子特异性甘油醛-3-磷酸脱氢酶（GAPDHs）基因被“敲除”的小鼠精子缺乏进行性运动能力，这支持了糖酵解的一个必要作用。在此，我回顾一些反对这一观点的证据。首先，对于精子较小的物种，单纯从线粒体扩散可能就足够了，而且较大精子所需的快速ATP传递可能通过腺苷酸激酶穿梭来实现。其次，α-氯醇的实验表明，尽管GAPDHs受到抑制，但精子在ATP浓度正常时仍能保持运动；只有添加葡萄糖且糖酵解中间产物大量积累时才会产生不利影响。这些观察结果削弱了GAPDHs基因敲除小鼠作为局部糖酵解起关键作用证据的说服力。第三，许多物种的精子在无糖培养基中可以长时间保持运动，除了犬类精子外，支持糖异生是一种可能解释的证据很薄弱。在大多数物种中，局部糖酵解不太可能是向鞭毛远端供应ATP的唯一途径。
