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博主胡德良:邢台学院外语系英语教授,中国译协专家会员,河北省译协常务理事,邢台市译协副会长。爱好翻译,内容涉及宇宙探秘、医疗卫生、家庭保健、生命科学、能源科学、地球科学、环境科学、散文小说和纪实文学等领域。所译文章曾见于《光明日报》、《科技日报》、《健康时报》、《健康报》、《英语世界》、《英语知识》、《科技英语学习》、《科学之友》、《科学与文化》、《世界科学》、《生命世界》等全国各大报刊。博客特色:英汉对照、图文并茂,融趣味性、科学性、知识性为一体。

性别之间微妙的平衡(图)  

2009-12-15 17:30:20|  分类: 生命科学 |  标签: |举报 |字号 订阅

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性别之间微妙的平衡(图) - 月亮飞船 - 欢迎光临月亮飞船的博客

正常的老鼠卵巢(左)和缺少Foxl2基因的老鼠卵巢(右)。

A Delicate Balance of Sexual Identity

By Gretchen Vogel    胡德良

The difference between male and female is smaller than one might think--at least on a cellular level. Researchers have found that they can change ovary cells into testicular cells in mice by turning off a single gene. The discovery provides new insights into the evolution of sex differences, and it may help doctors better understand sexual identity disorders and why some women go through early menopause.  

 雌雄之间的差异可能比想象的要小,至少从细胞的角度来说是这样的。研究人员发现,他们通过关闭一个基因就可以把老鼠的卵巢细胞变为睾丸细胞。这项发现使研究人员对性别的发育有了新的认识,同时也可以帮助医生们更好地认识性身份识别障碍,以及为什么一些妇会出现提前绝经。

 Scientists knew that the gene responsible for the fate switch, called Foxl2, was important to ovarian cells. But experiments with the gene had led to confusing results, says developmental biologist Mathias Treier of the European Molecular Biology Laboratory in Heidelberg, Germany. Female mice lacking the gene developed perfectly normal ovaries. After birth, however, the animals' ovaries started to deteriorate. But it was not clear what was going wrong.

 科学家们知道引起这种重大变化的基因叫做Foxl2Foxl2对于卵巢细胞是很重要的。然而,德国海德堡市欧洲分子生物学实验室的发育生物学家马赛厄斯·特雷伊尔说,利用这种基因所做的实验导致了含混不清的结果。缺少这种基因的雌鼠卵巢发育完全正常,可是在出生之后其卵巢就开始退化,不清楚出了什么问题。

 To learn more, Treier and his colleagues genetically engineered a mouse in which they could selectively turn off the Foxl2 gene in adult ovaries. With the gene inactive, a dramatic change took place in the female mice. Within 3 weeks, their ovaries were full of tubelike structures usually found in testicle tissue. Upon closer inspection, the researchers found that the ovarian cells had become cellular cross-dressers, displaying all the characteristics of several types of testicle cells, some of which produced levels of testosterone typical of an adult male. (There were no sperm present, however.)

 为了了解更多的情况,特雷伊尔及同事通过基因工程创造了一种老鼠,他们可以选择性地关闭成年雌鼠卵巢中的Foxl2基因。由于Foxl2基因不再活跃,雌鼠发生了显著的变化:在三周之内,它们的卵巢中充满了睾丸组织中常见的管状结构。经过更加仔细的检查,研究人员发现卵巢细胞成为“异装癖细胞”,显示出几种睾丸细胞的所有特性,其中一些细胞还分泌出不同水平的、代表着成年雄性的睾酮。(然而,没有出现精子。)

 Foxl2, it seems, is part of a larger genetic pathway that controls the identity of cells in the ovaries and testis. The researchers found that the protein made by the gene suppresses the activity of another gene called Sox9, which prompts the development of testicular cells. When Foxl2 is turned off, Sox9 is free to take over--and turn the ovary cells into testis cells, the team reports in today's issue of Cell. The work shows that the adult gonad has "remarkable plasticity," says developmental biologist Andrew Sinclair of the University of Melbourne in Australia, who was not involved in the research.

 Foxl2好象是更加广泛的基因途径中的一个环节,控制着卵巢和睾丸中的细胞特性。研究人员发现,Foxl2产生的蛋白可以抑制另外一种基因的活性,那种基因叫做Sox9Sox9可以促进睾丸细胞的发育。研究小组在今天出版的《细胞》杂志上报道:把Foxl2关闭之后,Sox9就可以自由地发挥作用——将卵巢细胞变成睾丸细胞。澳大利亚墨尔本大学的发育生物学家安德鲁·辛克莱没有参加这项研究,但他指出:这项研究表明成年老鼠的生殖腺具有“很大的可塑性”。

 During embryonic development, there are several mutually reinforcing gene pathways that keep an organism either male or female. Indeed, says developmental biologist Robin Lovell-Badge of the MRC National Institute for Medical Research in London, who worked with Treier on the study, there are so many overlapping mechanisms that keep the sexes developing in their own direction, "you would have thought that by the time you get to the adult, everything would be so hard-wired you couldn't change it." But the new work shows that by adulthood, the backup reinforcements are no longer active, so that a change in the levels of a single protein is enough to trigger a dramatic switch.

 在胚胎发育的过程中,有几种互相强化的基因途径可以决定一个有机体是雌还是雄。英国医学研究理事会(MRC)国家医学研究所的发育生物学家罗宾·洛弗尔-巴吉跟特雷伊尔一道进行了这项研究,他说:的确,有许多机制同时起作用,致使性别朝着自己的方向发育,“你本来可能会认为,在成年之前一切都是相当固定的,不可能使之改变。”可是这项新研究显示,在成年之前备用的强化机制不再活跃,因此仅仅改变一种蛋白质的水平就足以引起显著的变化。

 Mammals, fish, and birds have all evolved different systems of sex chromosomes that determine whether an organism is male or female, but the Foxl2 and Sox9 genes are conserved in all vertebrates. So Treier says that the yin-yang balance between the two is probably active in maintaining sex in a wide variety of animals. Several species of fish are known to be able to change their gender in adulthood, and Sinclair says the new results may explain how that happens. The pathway is also interesting for researchers studying early ovarian failure, which causes some women to undergo early menopause. And it may also help explain why some children develop sexual characteristics that don't match their chromosomal gender.

 哺乳动物、鱼类和鸟类都进化出了不同的性染色体系统,这些系统决定着有机体的雌雄,而Foxl2 Sox9两种基因存在于所有的脊椎动物中。因此特雷伊尔说:这两种基因之间的阴阳平衡很可能在保持多种动物的性别方面起到作用。据了解,好几种鱼在成年时会改变自己的性别。辛克莱说,这些新的研究成果可以解释这种变性是如何发生的。研究卵巢早衰的人员也对该途径感兴趣,卵巢早衰会使一些妇女提前绝经。这个途径还有助于解释为什么一些孩子发育出的性征与它们的染色体性别不相匹配。

 Lovell-Badge says he and his colleagues are now looking for whether a similar genetic trick can change male cells into female cells. In any case, he says, the findings disprove the idea, long held by developmental biologists, that female characteristics are a default setting that is overwritten by male genes--a bit of gender equality at the cellular level.

 洛弗尔-巴吉说,现在他和同事们正在研究能否利用同样的基因技术将雄性细胞变为雌性细胞。他说:不论如何,这些发现反驳了发育生物学家们长期持有的观点——雌性特征是雄性基因过度表达引起的默认设置。该研究算是从细胞的角度赢得了一点性别平等。

译自:美国《科学》杂志网站(10 December 2009

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