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1、请勿言性！俺们只是轮虫！： 水生微生物可以通过黄体酮自我克隆科学日报（2010，06,15） 一项新的研究表明：在性上面，水生微生物和人类有些重要的共同点。Barely visible without a microscope, rotifers eat algae and serve primarily as food for baby fish. But the females of certain rotifer species can do something quite unusual: they can reproduce asexually by creating clones
2、of themselves, or they can initiate a process that allows sexual reproduction by producing male rotifers.不借助显微镜的话几乎看不见，轮虫以藻类为食而轮虫又是鱼宝宝们的主食。不过雌性的轮虫却能做不寻常的事：它们可以通过自我克隆来进行无性繁殖，当然它们也能通过有性繁殖来制造雄性轮虫。The chemical mediator for this change from asexual to sexual reproduction turns out to be progesterone - a
3、simple molecule that also plays a vital role in regulating reproduction and sexual development in humans and many other species. Finding this sex steroid and its receptor in simple rotifers suggests that the progesterone signaling technique dates back hundreds of millions of years.促使它们由无性繁殖转向有性繁殖的化学
4、介质就是黄体酮 一个在调节人类和其他众多物种生殖和性发育方面起着至关重要的作用的化学分子。在结构简单的轮虫体内发现这样的性腺素和受体说明信令标示技术在数百万年以前就有了。Julia Kubanek说：“这真是一个革命性的启示，我们的研究显示在人和轮虫体内发现的同样的类固醇分子被用在了两个很不相同的方面”。她是乔治亚工学院生物专业的教授，同时也是这项研究的主要责任人之一。这项研究由国家科学基金会资助，按照日程将于2010年6月14日出版，最先发表在美国国家科学院学报的在线版期刊上面。该研究被认为是第一份以书面形式证明包括轮虫在内的简单生物群体存在对黄体酮的应用，而且数百万年来几乎没有大的变动。M
5、ost animals reproduce sexually, a method that makes a species more adaptable by facilitating the elimination of bad genes and creating potentially beneficial new gene combinations. Very simple organisms, such as bacteria, reproduce through cell division and obtain new genetic material from the envir
6、onment.The rotifer species Brachionus manjavacas is somewhere in between. During most of the year, the rotifer population consists only of females, which reproduce by creating clones of themselves. But when unfavorable environmental conditions threaten - such as the loss of algae food - about a thir
7、d of the rotifer population switches to sexual reproduction, which is the only way the creatures can produce eggs able to survive through a long winter.大部分动物都是有性繁殖的，通过这种方法可以淘汰不利的基因并潜在的创造有益的基因来更好的适应环境。十分简单的有机体，如细菌是通过细胞分裂来繁殖并从环境中获得新的遗传物质的。轮虫种群棘臂尾轮虫种群就介于两者（有性繁殖和无性繁殖）之间，在相当长的年月里轮虫种群都是由雌性轮虫构成的，它们主要是自我克隆而
8、来的。但当环境条件对它们不利的时候（如藻类食物的消失），大约三分之一的轮虫就会转向有性繁殖，以卵来熬过冬天，这个时候这是该生物生存下来的唯一方式Kubanek and her collaborators wanted to understand what was triggering that change, which begins with the production of male rotifers. The switching appears to depend on a pheromone protein that the rotifers release into the wat
9、er to indicate that other rotifers are nearby. When the rotifer population grows large enough to create a significant concentration of that protein, females start laying eggs that can develop as males. A population large enough to do that usually doesnt build up until fall in North America - when wi
10、nter and the end of the algae food supply are near.The rotifers are pretty good at figuring out when conditions are getting bad and when its time to produce males, have sex, make these overwintering eggs and call it a day, Kubanek said. They are really making some fairly sophisticated decisions abou
11、t when to have sex, and when to go it alone.To understand the complex process, the researchers combined several different research techniques to piece the puzzle together.Kubanek和她的合作者想知道是什么引起了那样的转变，那种以繁殖雄性轮虫开始的改变。这种转变似乎是依靠轮虫释放到水中的一种信息素蛋白质来提示附近的其他轮虫。当轮虫的数量达到一定程度，能释放相当浓度的蛋白质时，雌性就开始产卵，这些卵就是雄性轮虫卵。通常这种现
12、象只有在北美的时候才出现-当冬天临近，藻类食物快要断绝的时候。“轮虫能很好的估计什么时候环境变恶劣，什么时候应该繁殖雄性，什么时候该交配、产下过冬的卵，然后收工。”Kubanek说：“它们在什么时候交配什么时候独活的决策上真的是相当娴熟”。为了弄清这个复杂过程，研究者们用了好几项研究技术来分解这个谜团。Professor Terry Snell in Georgia Techs School of Biology, along with his students and collaborators at Woods Hole Oceanographic Institution, studied
13、 the partially-sequenced genome of the rotifer and located a receptor for a progesterone-like molecule. Then, using a fluorescent probe developed by James La Clair of the Xenobe Research Institute in San Diego, Paige Stout, a Ph.D. student in Georgia Techs School of Chemistry and Biochemistry showed
14、 that progesterone binds to a receptor in the reproductive systems of female rotifersThe researchers gained further evidence of progesterone receptors presence through the use of affinity chromatography, which used the same probe system to extract the receptor from a mixture of proteins contained in
15、 the rotifers. Further, 质谱的mass spectrometry indicated the presence of progesterone at parts-per-billion levels in rotifer massFinally, Snell and School of Biology research scientist Tonya Shearer demonstrated a direct connection between the hormone and the switch to sexual reproduction in the rotif
16、ers. They used RNA interference (RNAi) technology to silence the gene controlling the progesterone receptor, which reduced by nearly two-thirds the number of animals switching over to sexual reproduction in response to the progesterone signal.乔治亚理工学院生物系的Terry Snell教授同他的学生和伍兹霍尔海洋研究所的合作者研究了轮虫的部分测序的基因组，找出了一个类似黄体酮分子的受体。然后用James La Clair（圣地亚哥Xenobe 研究院）和Paige Stout（乔治亚理工学院化学系学生）研发的荧光探针，发现了了黄体酮附在雌性轮虫的生
