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
医学
Cholesterol plays a key role in the development of embryo cells, biologists have discovered. They say that this much maligned fa
Cholesterol plays a key role in the development of embryo cells, biologists have discovered. They say that this much maligned fa
admin
2014-01-15
33
问题
Cholesterol plays a key role in the development of embryo cells, biologists have discovered. They say that this much maligned fatty molecule, best known for its links to heart disease, helps to position a family of "controller" proteins that tell embryo cells how they should form.
In laboratory studies on fruit flies and mice, Phil Beachy and his colleagues at Johns Hopkins University in Baltimore looked at members of a family of controller proteins known as Hedgehog. Fruit fly embryos that lack the genes for these proteins develop a spiky appearance — hence the name. Biologists already know that Hedgehog proteins help to direct the development of embryo cells by delivering signals at the cell surface. The proteins only deliver their signals when they split in two, and one half binds to a lipid, a fatty molecule. Beachy’ s team discovered that this lipid is cholesterol.
In previous test-tube experiments, scientists have found that the concentration and distribution of Hedgehog proteins on the surface of embryo cells can be critical in determining their fate. For example, cells taken from the embryonic nervous system become motor neurons when exposed to low concentrations of Hedgehog proteins, while at high concentrations they turn into structural cells known as floor plates. Until now, however, no one knew what determined the concentration of the proteins on the surface of cells in the embryo.
Beachy’ s findings suggest that cholesterol’ s role is to allow the signaling proteins to enter cells. Since the lipid molecule is water-hating or hydrophobic, the researchers argue, it may act as a key, allowing the Hedgehog proteins to move through the hydrophobic membranes of target cells, or to stick to them. The results appear in the current issue of Science.
Researchers already know that cholesterol does some important jobs: for example, it is involved in the production of hormones and is vital for fertility and for the healthy membrane structure of cells. Beachy’ s latest results show that cholesterol is also needed for embryonic development. They also help to explain a long-known but mysterious finding that pregnant rats given drugs that block the manufacture of cholesterol produce deformed fetuses.
Gail Martin, a developmental biologist at the University of California, San Francisco, describes the findings as "exciting". They may also have wider implications, she says: it is likely that cholesterol’ s action is needed more generally for signaling between cells.
Beachy too believes that the findings may have "strong connections for human biology". For example, they throw light on a birth disorder that has been linked to the mother’ s inability to make cholesterol. This disorder, Smith-Lemli-Opitz syndrome, affects about 1 in 9000 newborn babies, causing defects such as small head size.
Beachy’ s findings, according to Martin,______.
选项
A、can be applied to human biology
B、may throw light on the connections between human beings and other species
C、are limited to fruit flies and mice
D、can explain the mother’s inability to make cholesterol
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/kbT3777K
本试题收录于:
医学博士外语题库考研分类
0
医学博士外语
考研
相关试题推荐
High-speedlivinghasbecomeafactoflife,andthefranticpaceistakingitstoll,accordingtosciencewriterJamesGleick.
High-speedlivinghasbecomeafactoflife,andthefranticpaceistakingitstoll,accordingtosciencewriterJamesGleick.
High-speedlivinghasbecomeafactoflife,andthefranticpaceistakingitstoll,accordingtosciencewriterJamesGleick.
ManyCanadiansenjoytheluxuryofalargeamountoflivingspace.Canadaisvast,andthehomesarelargeaccordingtothestan
ManyCanadiansenjoytheluxuryofalargeamountoflivingspace.Canadaisvast,andthehomesarelargeaccordingtothestan
A、Thecommercialcompanieshaveinvestedalotinthenewmachine.B、Thefurtherdevelopmentofthemachineisinfinancialtrou
Thebiosphereisthenamebiologistsgivetothesortofskinonthesurfaceofthisplanetthatisinhabitablebylivingorgani
Untilafewyearsagomostexpertsbelievedthatyoungchildrencouldn’tlie.ThelatedevelopmentalpsychologistJeanPiagetbe
随机试题
简述企业会计组织机构及其岗位职责设计的原则。
下列选项中,对现代学校教育制度改革的趋势表述不正确的一项是()
A23~26cmB25~28cmC18~20cmD8.5~9.5cmE12.5~13cm坐骨结节间径正常值为
MENⅡ型指
合同中的数量条款为“1000M/TWtih5%moreorlessatSeller’soption”,则卖方交货数量可以是()。
保证合同的内容包括()
在一百多年的发展历程中,中国银行始终秉承追求卓越的精神,将,()作为办行之魂,将诚信至上作为立行之本,将改革创新作为强行之路,将以人为本作为兴行之基,树立了卓越的品牌形象,得到了业界和客户的广泛认可和赞誉。
2005年,四个银行的净利息收入的总和约为()。
“自由女神像”是哪个国家送给美国的礼物?()(中山大学2011)
建立远程视图必须首先建立与远程数据库的______。
最新回复
(
0
)