首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Researchers have created male mice with no trace of a Y chromosome, supposedly the defining hallmark of being male. Reproduct
Researchers have created male mice with no trace of a Y chromosome, supposedly the defining hallmark of being male. Reproduct
admin
2019-08-27
92
问题
Researchers have created male mice with no trace of a Y chromosome, supposedly the defining hallmark of being male.
Reproductive biologist Monika Ward of the University of Hawaii in Honolulu and colleagues started with mice that have only one X chromosome (and no second sex chromosome). Normally those animals would develop as females. But when the researchers manipulated genes found on the X and another chromosome, the mice became males that could produce immature sperm. Those engineered males fathered offspring with reproductive assistance from the researchers, who injected the immature sperm into eggs, Ward and colleagues report in the Jan. 29 Science.
The experiments demonstrate that there are multiple ways to make males, says Richard Behringer, a developmental geneticist at MD Anderson Cancer Center in Houston. "They’ve done it without any Y chromosome gene information, " he says. "There’s not even a sniff of the Y around."
At first glance, the experiments would seem to suggest Y chromosomes aren’t necessary for reproduction, which hints that evolution may eventually show Y’s the door. "To me it is a paradigm of the decline and fall of the Y chromosome, " says reproductive biologist Jennifer Marshall Graves of La Trobe University in Melbourne, Australia.
But Ward and other researchers say the Y isn’t going anywhere and that interpreting the new results as the chromosome’s death knell is wrong. Because the Y-less males needed help to reproduce, "clearly we need the Y chromosome for full natural male reproduction, " says Mary Ann Handel, a reproductive biologist at the Jackson Laboratory in Bar Harbor, Maine.
Ward and colleagues had previously shown that two Y chromosome genes—Sry and Eif2s3y— are crucial for male mouse development. Sry is a master gene that turns on male developmental programming in early embryos. It turns on a gene called Sox9, which then sets off a biochemical chain reaction that leads to male development.
But in the new experiments, the researchers turned on Sox9 through other means. Activating Sox9 in a genetically female embryo will cause it to develop as a male, Ward and colleagues found. But those males didn’t make sperm. "The testes were empty, " says Ward.
In order to produce sperm, mice need the Eif2s3y gene, the researchers had previously discovered. In the new experiment, the mice were missing the gene because they didn’t have Y chromosomes. So researchers substituted a similar gene from the X chromosome called Eif2s3x. Only one copy of the Y version is needed to make immature, tailless sperm, but it takes at least five copies of the X version to do the same thing. "This indicates that the Y chromosome gene is the strong one, " says Ward.
Her research suggests that the Y chromosome has optimized production from genes that are necessary for making males. "Making just the right dose of male development factors is how the Y protects itself from evolutionary erasure, " Ward says. "Our work does not support that the Y chromosome will disappear."
Graves disagrees. Ward’s work is "a lovely example of how you can lose even a really important gene, " she says. At least two species of rodents have already jettisoned their Y chromosomes entirely. Primates, including humans, don’t have Eif2s3y genes on their Y chromosomes. The new work may help explain how primates get along without the gene, Graves suggests, and the research may "give us useful information about what happens at the end of the life of the Y chromosome".
Why is Eif2s3y gene crucial for male mouse development?
选项
A、It is a master gene that turns on male developmental programming in early embryos.
B、It sets off a biochemical chain reaction that leads to male development.
C、Mice need it to produce sperm.
D、Mice need it to develop testes.
答案
C
解析
本题为事实细节题。根据第八段第一句“In order to produce sperm,mice need the Eif2s3y gene”可知,为了产生精子,老鼠需要Eif2s3y基因。C项“老鼠需要它来产生精子”,符合原文意思。因此,C项正确。
转载请注明原文地址:https://kaotiyun.com/show/LpUO777K
0
考博英语
相关试题推荐
OurculturehascausedmostAmericanstoassumenotonlythatourlanguageisuniversalbutthatthegesturesweuseareunderst
Anyhopeofafountainofyouthtostoppeoplefromgettingolderisalongwayoffwithsciencejustbeginningtounderstandth
每逢新年,人们往往要定新年决心(NewYearresolutions)。这是很多人下决心改变旧习惯、适应新的学习和生活方式的时刻。新年决心像其他很多时尚一样,说起来简单做起来难。通过艰苦工作和坚持不懈,把自己的目标、梦想、决心和远大期望变成现实真不是容
YouaresupposedtowritealettertoaprofessorinauniversityintheUnitedStatesorUK,requestingforthepossibilityof
中国人的年讲究的就是一个团聚,正如中国知名作家冯骥才所讲:春节是中国人的“情感时刻”。这一天无论你身在何处,回家团圆是唯一的主题,思乡情感也要在这一刻得到宣泄。对于英国留学生们来说,春节回家的愿望,非要天时地利人和,多重因素都给力,才能够得以实现。每年的春
Justfourbitsofinformationcollectedfromashopper’screditcardcanbeusedtoidentifyalmostanyone,researchershavefou
Justfourbitsofinformationcollectedfromashopper’screditcardcanbeusedtoidentifyalmostanyone,researchershavefou
Asabusinessmodel,theworldofpublishinghasalwaysbeenasomewhatsleepyenclave,butnowallthatseemspoisedtochange.
中俄油气合作目前发展的势头很好,在未来合作的道路上,可能还会遇到各种各样的困难,有时甚至会出现挑战大于机遇的情况。中俄双方现在都已认识到,中俄油气合作是大势所趋,对双方谋划后金融危机时代本国经济的发展,都有着重大的战略意义。尤其是对中方而言,在经济全球化的
Hedidnotrelishappealingamongsthisfriendsand______oftheircriticismorcensure.
随机试题
如果装配间隙大小不均匀,会()。
灭菌是指杀灭或清除传播媒介上所有微生物的方法,下列哪种微生物是否被杀灭常作为判断指标
甲状腺相关性眼病常引起眼外肌的肥大,下列的叙述不正确的是
还原当量经琥珀酸氧化呼吸链可得还原当量经ND氧化呼吸链可得
A.收敛邪气B.腻膈碍胃C.伤阴助火D.伤津伐胃E.耗气伤阴根据五味的所示效用,辛味的不良效用为
肾气不固所导致的小便改变为
土中黏粒含量越多,土的可塑性越高,塑性指数越小。()
人体脊柱4个生理弯曲中,_______弯和_______弯是后天形成的。
下列是有关自然环境与人类社会关系问题的材料:材料1不同气候的不同需要产生了不同的生活方式;不同的生活方式产生了不同种类的法律。热带民族的怯懦常常使这些民族成为奴隶,而寒冷气候的民族的勇敢使他们能够维护自己的自由。这是自然的原因所产生的后果。居住在山地
BullyingandChildrenA)Whatyoursonisdescribingisbullying,plainandsimple.Althoughitislateintheschoolyear,yous
最新回复
(
0
)