英国剑桥大学和澳大利亚莫纳什大学的研究人员称，他们从基因角度找到一种阻止精子游泳的方法，有望在掌握一种新的男性避孕药方面获得关键性突破。这项研究结果刊登在最新一期《公共科学图书馆—遗传学》杂志上。
从世界范围看，采取避孕措施的人口中，八成以上是女性绝育和使用宫内节育器，男性绝育只占9.2%。在药物避孕人群中，也主要由女性服用避孕药物。而采取男性避孕措施的人口数量之所以偏低，主要是因为目前尚未开发出绝对安全的男性避孕药。
领导这项研究的莫纳什大学教授莫伊拉表示，他们在一项更好地了解男性不育的研究中发现，当小鼠的一个特定基因副本突变后，其产生精子的尾巴会短17%，导致它们游泳能力骤降。该基因称为RABL2，其会比正常副本导致小鼠产精量减少50%。莫伊拉说：“当RABL2基因突变，很容易造成不育。此外，精子的运动性对于男性的生育能力是绝对必要的，洞察精子尾部的功能可能会开发出基于男性的紧急避孕药物。”
进一步的研究表明，该基因产生称为鞭毛内传输的蛋白质，这种蛋白质与其他分子相互作用，不断加长精子的尾部以承载遗传信息。研究人员珍妮·弗罗说：“数据表明，如果RABL2功能障碍，就意味着承载到精子尾部的信息有缺陷。而且由于RABL2不正常，精子尾部承载的信息也会减少。最终导致精子的生成和活力异常。”
由于基因突变导致精子数量减少，并且妨碍其游动能力，由此，科学家希望可以开发出一种避孕药，以降低其产生蛋白质的水平。但是，由于这种蛋白质在身体其他部位被发现少量存在，包括大脑、肾脏和肝脏之中，未来的这类药物还将对相关安全性展开评估。（生物谷Bioon.com）
doi: 10.1371/journal.pgen
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RAB-Like 2 Has an Essential Role in Male Fertility, Sperm Intra-Flagellar Transport, and Tail Assembly
Lo JC, Jamsai D, O'Connor AE, Borg C, Clark BJ, Whisstock JC, Field MC, Adams V, Ishikawa T, Aitken RJ, Whittle B, Goodnow CC, Ormandy CJ, O'Bryan MK.
A significant percentage of young men are infertile and, for the majority, the underlying cause remains unknown. Male infertility is, however, frequently associated with defective sperm motility, wherein the sperm tail is a modified flagella/cilia. Conversely, a greater understanding of essential mechanisms involved in tail formation may offer contraceptive opportunities, or more broadly, therapeutic strategies for global cilia defects. Here we have identified Rab-like 2 (RABL2) as an essential requirement for sperm tail assembly and function. RABL2 is a member of a poorly characterized clade of the RAS GTPase superfamily. RABL2 is highly enriched within developing male germ cells, where it localizes to the mid-piece of the sperm tail. Lesser amounts of Rabl2 mRNA were observed in other tissues containing motile cilia. Using a co-immunoprecipitation approach and RABL2 affinity columns followed by immunochemistry, we demonstrated that within developing haploid germ cells RABL2 interacts with intra-flagella transport (IFT) proteins and delivers a specific set of effector (cargo) proteins, including key members of the glycolytic pathway, to the sperm tail. RABL2 binding to effector proteins is regulated by GTP. Perturbed RABL2 function, as exemplified by the Mot mouse line that contains a mutation in a critical protein-protein interaction domain, results in male sterility characterized by reduced sperm output, and sperm with aberrant motility and short tails. Our data demonstrate a novel function for the RABL protein family, an essential role for RABL2 in male fertility and a previously uncharacterised mechanism for protein delivery to the flagellum
