科学美国人60秒 SSS 2014-07-18_在线英语听力室

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Wheat helped create civilization in the Middle East. It’s a staple¹ crop for 30 percent of the world’s population. And now, with the publication of four articles in the journal Science, we’re close to a detailed² understanding of the bread wheat genome.

Wheat is tough to sequence. It’s gone through multiple hybridizations, making its genome five times larger than a human one. Plus there are many redundancies: more than 80 percent of the genome is made of repeated DNA³ sequences. So the typical whole-genome shotgun approach—breaking genomes into segments and then reassembling them—doesn’t work for wheat.

Instead, an international consortium devised another strategy, involving physically⁴ mapping individual chromosomes⁶ and chromosome⁵ arms.

One paper details a draft of the entire genome of bread wheat. Another identifies all the genes⁷ on the largest of the plant’s 21 chromosomes. Some 75,000 genes have been mapped. The methods in the second paper will help scientists map the remaining chromosomes. They say it should take another three years.

Knowing exactly which genes are responsible for talents such as tolerating drought or improving yields should allow researchers to mine the genome and to quickly produce new and better wheat varieties to bring us our daily bread.

Thanks for the minute, for Scientific Americans 60-Second Science. I am Cynthia Graber.

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1 staple
n.主要产物，常用品，主要要素，原料，订书钉，钩环；adj.主要的，重要的；vt.分类
参考例句：
Tea is the staple crop here.本地产品以茶叶为大宗。 Potatoes are the staple of their diet.土豆是他们的主要食品。

2 detailed
adj.详细的，详尽的，极注意细节的，完全的
参考例句：
He had made a detailed study of the terrain.他对地形作了缜密的研究。 A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

3 DNA
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句：
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。

4 physically
adj.物质上，体格上，身体上，按自然规律
参考例句：
He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。 Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。

5 chromosome
n.染色体
参考例句：
Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。 A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

6 chromosomes
n.染色体( chromosome的名词复数 )
参考例句：
Chromosomes also determine the sex of animals. 染色体也决定动物的性别。来自《简明英汉词典》 Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。来自《现代汉英综合大词典》

7 genes
n.基因( gene的名词复数 )
参考例句：
You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。来自《简明英汉词典》 Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。来自英汉非文学 - 生命科学 - 生物技术的世纪

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科学美国人60秒 SSS 2014-07-18