时间:2019-01-02 作者:英语课 分类:60秒科学


英语课

A couple million years ago, mammoths migrated north from Africa to colonize 2 Eurasia. Sometime around then a massive ice age kicked in—and it was stay warm or die. So their tails and heat-shedding ears shrunk, and they grew thick coats of oily fur. 


But if you're out in the cold all day you also need some biochemical adjustments. Hemoglobin is the protein in red blood cells that delivers oxygen to your tissues. And it doesn't off-load oxygen well at low temperatures; it just clings to it more tightly. So mammoths solved that problem by evolving hemoglobin that releases oxygen more easily in the cold. That’s according to a study published in the journal Nature Genetics. 


Researchers got the DNA 3 that codes for hemoglobin from a 43,000-year-old mammoth 1 specimen 4. They then used E. coli bacteria to produce actual mammoth hemoglobin. Then they compared mammoth hemoglobin to that of their living cousins, Asian elephants, at 37, 25 and 10 degrees Celsius 5. Due to just a few key structural 6 changes, mammoth hemoglobin can release oxygen more readily at cold temperatures. Which was just the thing to help mammoths keep their cool.


—Christopher Intagliata

 



n.长毛象;adj.长毛象似的,巨大的
  • You can only undertake mammoth changes if the finances are there.资金到位的情况下方可进行重大变革。
  • Building the new railroad will be a mammoth job.修建那条新铁路将是一项巨大工程。
v.建立殖民地,拓殖;定居,居于
  • Around 700 Arabs began to colonize East Africa.公元700年阿拉伯人开始把东非变为殖民地。
  • Japan used to colonize many countries in Asia.日本曾经殖民过许多亚洲国家。
(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。
n.样本,标本
  • You'll need tweezers to hold up the specimen.你要用镊子来夹这标本。
  • This specimen is richly variegated in colour.这件标本上有很多颜色。
adj.摄氏温度计的,摄氏的
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
adj.构造的,组织的,建筑(用)的
  • The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
  • The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。
学英语单词
a drone
ACL-60
Alexandrian Wiccan
alizarin blue-black nb
alpha paper
antilock
bandel
be in the front line
be incident upon
bilderback
blending bunker
bln
bringing you down
calcaneocavus
cam action reel
camouflage building
cAMP receptor protein
caribbean blue
cathe
chemers
chopsteak
CM copper
coleroa chaetomium
cppd
decision network
diergism
dignifying
dipped
electrode earth
error comparator
few-group model
filiality
foreign exchange turnover
forthwax
fractal dimension
frozen-heave force
fuel breather
gangway width
gas emanation
Gauss-Jordan elimination method
general pressure drop
generator cut out
ground return circuit
haugh unit
have the face to do something
incendiary fire
individual life policy
inspectingly
interstade
intransitivize
jakowski
jostled
Kaitumälven
knife cheek
late-onset desister trajectory
linguocentric
Lutembacher syndrome
madia-oil
manpowers
melanoderma cachecticorum
mourner
multi-way connector
mystic meg
non-rationality
non-trivial
nonterminal position
not care a chip
Nothofagidites
oil absorption of talc
oundy moulding
photopheresis
prayer stick
prepurchase customer service
real-time multicomputing
Recombinate
resting metabolism
robo-
rudimentum processus vaginalis
ruhh
safety drilling method
salganea taiwanensis
scalar impedence
separate bill of lading
service revenue
shaft-basis system
sodium expulsion
Soleymān Kalay
stentor steel
survival instinct
take a noble part
tank pressure gauge
telepathist
terra japonica
they-all
tunkus
under-glaze
underwater concreting
user effort
uterine cotyledons
utilization coefficient of strokes
webcasters
wine set