时间:2019-01-20 作者:英语课 分类:2014年Scientific American(九)月


英语课

 When you hear the word “mutation 1,” you may think of something destructive, or of Marvel’s X-Men. But some mutations—which are just differences in DNA 2—can be historic. Take, for example, a genetic 3 sequence found in the vast majority of people from Tibet.


 
Millions of Tibetans spend their days at average elevations 4 of nearly 15,000 feet—that’s more than half the height of Mount Everest. Up there, the air is thin—with 40 percent less oxygen than at sea level. That lack of O2 would leave most Westerners struggling for breath, but Tibetans seem to breathe easy.
 
To find out how these highlanders cope, researchers compared the DNA of 90 Tibetans to that of people who are not altitude adapted. And they discovered a single change that prevents Tibetans’ blood from becoming dangerously clogged 5 with red blood cells—a response that can be deadly for non-native mountaineers. The finding is described in the journal Nature Genetics.
 
This mutation appears to have originated just 8,000 years ago. But it’s so advantageous 6 that today nearly 90 percent of Tibetans have it. While it’s virtually absent in even closely related lowland neighbors.
 
The finding demonstrates that a really useful mutation will always rise to the top.
 
— Karen Hopkin

n.变化,变异,转变
  • People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
  • So far the discussion has centered entirely around mutation in the strict sense.到目前为止,严格来讲,讨论完全集中于围绕突变问题上。
(缩)deoxyribonucleic acid 脱氧核糖核酸
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
adj.遗传的,遗传学的
  • It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
  • Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
(水平或数量)提高( elevation的名词复数 ); 高地; 海拔; 提升
  • Weight of the crust changes as elevations are eroded and materials are deposited elsewhere. 当高地受到侵蚀,物质沉积到别的地方时,地壳的重量就改变。
  • All deck elevations are on the top of structural beams. 所有甲板标高线均指结构梁顶线。
(使)阻碍( clog的过去式和过去分词 ); 淤滞
  • The narrow streets were clogged with traffic. 狭窄的街道上交通堵塞。
  • The intake of gasoline was stopped by a clogged fuel line. 汽油的注入由于管道阻塞而停止了。
adj.有利的;有帮助的
  • Injections of vitamin C are obviously advantageous.注射维生素C显然是有利的。
  • You're in a very advantageous position.你处于非常有利的地位。
学英语单词
according file
aceclofenac
adsorption barriers
aerophilatelies
appredicate
ara ararauna
assembly subroutine
attenuation distance
availability sample
bright future
broad outline
bullactophotodermatitis
cavity block
changing-note
charactersketch
circular disc
climaxes
cooch behar
crocacin
data facility storage management subsystem
deschler
dihydroxyls
doeskins
duckoy
elephant-joke
embezzle public funds
equivariant cobordisms
excess risk
expenditure category
fast and slow method of casting
furliker
gaussian randomprocess
gllery
glueyest
Goongarrie, L.
headstep settling time
hopeline
hot lunches
immediate dominance condition
Impossibility Performance
incombustibility
iodoglobulin
iridium lamp
IUWCC
Lachnospiraceae
land-based pollution source
large-end
lime superphosphate
Lower Empire
magnetron type traveling wave tube
Manuel Ribas
Melica longiligulata
microtrabecular
mobocracy
nonagreeing
optical ring resonator
other composite material container
otitis parasitica
oversolds
paleophytologist
pareccrisis
peagreen
pentanobrnamide
phonetic reference
pink stern ship
plectorhinchus albovittatus
prequark
prime products
pseudo animes
radial engine
read method of childbirths
rembles
resilient joint
retaining water
rhamnopyranose
rotary forging
Rungwa
send to dorse
settled organism
sign up now
single-ram booster
skybus
strain cracking
stulled open stoping
sufficed
suspension roof support
temperature shock
term of residence
texass
therapeutic agents
thromme
tithonius
total radiation radiometer
traverse time
unevaporate
uredo rubi-swinhoei
valib
weirdish
Weisi
Willis' arteries
Zayn Malik
zelnickmedia