六级课程经典
零基础适用HOT
去试听
六级1对1
定制化
核心词 背词计划
0元
听力 提升必看
0元
阅读 冲刺200+
0元
写作 高分模板
0元
历年真题大全
免费
模考 水平测试
热门
1V1速成方案VIP
英语六级听力确实有一定难度,所以这就更需要同学们多加练习。VOA听力材料是很好的英语六级听力练习素材。现在距离2014年12月的英语六级考试还有三个多月的时间,大家只要从现在开始坚持练习,一定会出现奇迹的。下面是小编为大家2014年12月英语六级听力练习:VOA常速英语(4),供各位练习。
Scientists have just sequenced the genome of a fly native to Antarctica, the coldest, driest and windiest place on the planet, a finding that may lead to a wider understanding of how these bugs evolved to cope with the environment.
The fly, named Belgica antarctica, is a survivor, or as Washington State University evolutionary biologist Joanna Kelley likes to put it…an extremophile.
“This fly has to withstand freezing, extreme temperature changes so in the Antarctic summer it’s on the rocks and those are getting quite hot," Kelley said. "But imagine the Antarctic winter, it’s very dark and cold. There’s a lot of UV [ultraviolet] radiation. There’s dehydration. And anything you can imagine as an extreme pressure, this fly probably encounters it.”
Common fly
The fly is a midge, a group of small flies found practically everywhere on earth.
This midge has evolved to survive in the extreme environment of the rocky outcrops of the Antarctic Peninsula.
It is wingless, so it can't be swept up by the wind and blown into the sea. It can also tolerate 40 percent or more water loss in its cells, more than double that of other midges.
Kelley says the fly spends two years as larvae over two cold seasons.
“They look like dried up little raisins and that’s how they survive the winter," she said. "They are not developmentally active during that time, but they are still alive. This begs the question of, 'Does the small genome somehow enable them to go through that process, or the growing process in the summer more rapidly, or facilitate that somehow?'”
Smallest bug sequenced
Belgica antarctica is the first polar insect and the first freeze-tolerant insect whose genome - or genetic material - has been sequenced.
It is also the smallest bug sequenced to date. Its genome has 99 million base pairs, the DNA building blocks of an organism. That's tiny compared with the human genome which has 3.2 billion base pairs.
Kelley says the genome gives researchers a framework to study the organism in much more depth. For example, she says, they can look for what triggers its genes to activate a protein in response to heat or cold stress.
“The heat shock proteins are important in this fly, particularly because they are expressed all the time," she said. "In other organisms, heat shock proteins, which are turned on in response to temperature or other stresses, in the fly they are turned on all the time. And this process may give us insight into how the fly is able to survive over the winter.”
Possible medical advances
Kelley says understanding how the freeze tolerant mechanism works in a bug could lead to developments outside the insect world.
The most direct human application, she says, might be in cryo-preservation or the freezing of human cells or tissues for medical purposes.
The study is published in the journal Nature Communications.
新东方英语六级优惠好课↓↓↓
课程名称 | 课程亮点 | 试听 |
【小班课】英语六级零基础无忧计划 | 1V1答疑 | 免费试听 |
【专项】六级暑假备考全规划 | 单项全面进阶 | 免费试听 |
【阅读】六级阅读解题技巧大揭秘 | 双师精讲阅读 | 免费试听 |
【100%返现】英语六级救命班 | 考前冲分快准狠 | 免费试听 |
了解更多四六级课程 |
资料下载
2022年大选英语四级词汇完整带音标
发布时间:2020-04-15关注四六级小助手服务号
回复【过级词汇】获取
刘一男六级核心词汇完整版
发布时间:2020-04-15关注四六级小助手服务号
回复【过级词汇】获取
新东方英语口语终极教程word版
发布时间:2020-04-15关注四六级小助手服务号
回复【口语提升】获取
大学英语六级:练口语及单词lesson1-9
发布时间:2020-04-15关注四六级小助手服务号
回复【口语提升】获取
新东方在线[四六级王牌团队]典藏笔记
发布时间:2019-10-25关注四六级小助手服务号
回复【典藏笔记】获取
英语六级过级备考资料:经验+计划+语法
发布时间:2019-10-25关注四六级小助手服务号
回复【过级经验】获取
大学英语六级阅读解题经验技巧
发布时间:2019-10-25关注四六级小助手服务号
回复【阅读礼包】获取
英语四级写作诵读193经典句
发布时间:2019-10-25关注四六级小助手服务号
回复【写作指导】获取
英语六级听力讲义汇总资料
发布时间:2019-10-25关注四六级小助手服务号
回复【听力礼包】获取
英语六级口语考试练习小积累
发布时间:2019-10-25关注四六级小助手服务号
回复【口语提升】获取
大学英语六级核心高频词汇
发布时间:2019-10-25关注四六级小助手服务号
回复【过级词汇】获取
关注四六级小助手服务号回复【典藏笔记】获取
关注四六级小助手服务号,
获取学习资料
推荐阅读
更多>>英语六级听力是考试中难度系数较大的一项,对于大多数考生来说听力,部分都是短板,也是导致大家不能一次通过的原因,为帮助大家有效备
英语六级听力是考试中难度系数较大的一项,对于大多数考生来说听力,部分都是短板,也是导致大家不能一次通过的原因,为帮助大家有效备
英语六级听力是考试中难度系数较大的一项,对于大多数考生来说听力,部分都是短板,也是导致大家不能一次通过的原因,为帮助大家有效备
英语六级听力是考试中难度系数较大的一项,对于大多数考生来说听力,部分都是短板,也是导致大家不能一次通过的原因,为帮助大家有效备
英语六级听力是考试中难度系数较大的一项,对于大多数考生来说听力,部分都是短板,也是导致大家不能一次通过的原因,为帮助大家有效备
专项提升公开课
更多>>136小时干货精讲,包邮3斤礼盒,无忧换课
价格 : ¥269
限报人数:1000人
随报随学 告别‘小聋瞎’
价格 : ¥0
限报人数:1000人
资料下载
更多>>关注四六级小助手服务号
回复【过级词汇】获取
关注四六级小助手服务号
回复【过级词汇】获取
关注四六级小助手服务号
回复【口语提升】获取
关注四六级小助手服务号
回复【口语提升】获取
关注四六级小助手服务号
回复【典藏笔记】获取
关注四六级小助手服务号
回复【过级经验】获取
关注四六级小助手服务号
回复【阅读礼包】获取
关注四六级小助手服务号
回复【写作指导】获取
关注四六级小助手服务号
回复【听力礼包】获取
关注四六级小助手服务号
回复【口语提升】获取
关注四六级小助手服务号
回复【过级词汇】获取
阅读排行榜
相关内容