人体虱子基因组定序成功
文章来源:未知 文章作者:meng 发布时间:2010-06-22 00:49 字体: [ ]  进入论坛
(单词翻译:双击或拖选)

Like an unwelcome houseguest or itinerant1(巡回的,流动的) squatter2(擅自居住) , the human body louse(虱子) shows up when times are bad and always makes them worse. Now a multi-institutional team reports that it has sequenced the body louse genome, an achievement that will yield new insights into louse – and human – biology and evolution. The study, which also sequenced the genome of a microbe that lives inside the body louse, appears in Proceedings3 of the National Academy of Sciences.

Thanks to its tenacity4(固执,任性) , the tiny, blood-sucking parasite5(寄生虫) Pediculus humanus humanus L. has witnessed, and played a role in, millions of years of human history. The body louse spread epidemic6 typhus(流行性斑疹伤寒) and what is now termed trench7 fever to Napoleon's retreating army in Russia in 1812, and body lice plagued Lewis and Clark on their adventures in the New World.

The human body louse seems to appear out of nowhere during economic downturns, wars and other crises that cause people to live in unsanitary(不卫生的) conditions. It is closely related to the head louse, Pediculus(虱) humanus capitis, which also feeds on human blood. But the body louse lives in clothing and, unlike the head louse, can spread bacterial8 diseases.

The body louse genome is the smallest known genome of any insect, said University of Illinois entomology(昆虫学) professor Barry Pittendrigh (pronounced PITT-in-dree), who led the drive to fund the project and coordinated9 the international team of scientists who analyzed10 the sequence. The size of the body louse genome probably reflects its rather protected habitat and predictable diet, he said.

"The ecology of lice is very, very simple. It either lives in your hair or on your clothing, and it has one type of meal, and that's blood," he said. "So most of the genes11 that are responsible for sensing or responding to the environment are very much reduced."

The genome analysis found very few genes for light-sensing protein receptors, for example. University of Illinois entomology professor Hugh Robertson was responsible for sorting out(挑选出) the genes contributing to chemical sensing, and discovered that the louse has significantly fewer taste and odorant(有气味的) receptors than other insects.

The body louse also has "the smallest number of detoxification(解毒) enzymes12 observed in any insect," the researchers wrote. John Clark, of the University of Massachusetts at Amherst, and Si Hyeock Lee, of Seoul National University, led this part of the analysis. The body louse's pared-down list of detoxifying(净化,排毒) enzymes makes it an attractive organism for the study of resistance to insecticides or other types of chemical defense13, Pittendrigh said. University of Illinois entomology professor and department head May Berenbaum and former graduate student Reed Johnson contributed to this effort.

The body louse is completely dependent on humans for its survival; it will die if separated from its host for very long. It is just as reliant(依赖的,可靠的) on a microbe that lives inside it: the bacterium14 Candidatus Riesia pediculicola.

In the Riesia genome, the team found genes for the production of an essential nutrient15, pantothenate(泛酸盐) (Vitamin B5), which the louse requires and cannot make on its own. The Riesia genome also is quite small in comparison to its closest "free-living" relatives. So too are the genomes of the bacterial pathogens that the body louse transmits to its human hosts: Rickettsia prowazekii(普氏立克次体) (which causes epidemic typhus), Borrelia recurrentis(回归热螺旋体) (the agent of relapsing fever) and Bartonella quintana(五日热巴尔通体) (which causes trench fever五日热,战壕热). This, the researchers report, will make the body louse a useful tool for understanding the co-evolution of disease-carrying parasites16 and their bacterial co-conspirators.

The body louse genome will aid a host of other lines of research, Pittendrigh said.

"Lice have been used to understand human evolution and migration17. They've been used to estimate when we started wearing clothing," he said. "The genome should also help us develop better methods of controlling both head and body lice."

"Beyond its importance in the context of human health, the body louse genome is of considerable importance to understanding insect evolution," Berenbaum said. "It is only the second genome sequenced to date of an insect with gradual development – that is, that does not undergo profound anatomical(解剖的) and ecological18 change as it matures from egg to adult. Although most of the insect species on the planet undergo complete metamorphosis(全变态) – developing from egg to caterpillar19(毛虫) to pupa to adult – in fact gradual metamorphosis(变形,变质) is the older developmental program. The body louse genome can provide a baseline for understanding how complete metamorphosis, a key to insect domination of the planet, came to evolve."



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1 itinerant m3jyu     
adj.巡回的;流动的
参考例句:
  • He is starting itinerant performance all over the world.他正在世界各地巡回演出。
  • There is a general debate nowadays about the problem of itinerant workers.目前,针对流动工人的问题展开了普遍的争论。
2 squatter 6e108420db496a4914be84015ab9c256     
n.擅自占地者
参考例句:
  • The squatter settlements originally came into being through illegal land invasions. 违章建筑区最初是通过非法的土地占有而形成的。
  • Squatter control is maintained by regular patrols and hut-to-hut checks. 当局定期逐户视察所有寮屋,以收管制之效。
3 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
4 tenacity dq9y2     
n.坚韧
参考例句:
  • Tenacity is the bridge to success.坚韧是通向成功的桥。
  • The athletes displayed great tenacity throughout the contest.运动员在比赛中表现出坚韧的斗志。
5 parasite U4lzN     
n.寄生虫;寄生菌;食客
参考例句:
  • The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
  • I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫,我要自己养活自己。
6 epidemic 5iTzz     
n.流行病;盛行;adj.流行性的,流传极广的
参考例句:
  • That kind of epidemic disease has long been stamped out.那种传染病早已绝迹。
  • The authorities tried to localise the epidemic.当局试图把流行病限制在局部范围。
7 trench VJHzP     
n./v.(挖)沟,(挖)战壕
参考例句:
  • The soldiers recaptured their trench.兵士夺回了战壕。
  • The troops received orders to trench the outpost.部队接到命令在前哨周围筑壕加强防卫。
8 bacterial dy5z8q     
a.细菌的
参考例句:
  • Bacterial reproduction is accelerated in weightless space. 在失重的空间,细菌繁殖加快了。
  • Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。
9 coordinated 72452d15f78aec5878c1559a1fbb5383     
adj.协调的
参考例句:
  • The sound has to be coordinated with the picture. 声音必须和画面协调一致。
  • The numerous existing statutes are complicated and poorly coordinated. 目前繁多的法令既十分复杂又缺乏快调。 来自英汉非文学 - 环境法 - 环境法
10 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
11 genes 01914f8eac35d7e14afa065217edd8c0     
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
12 enzymes 7881ad8ce9c83424f7874e70266ed2d8     
n. 酶,酵素
参考例句:
  • It was said that washing powders containing enzymes remove stains more efficiently. 据说加酶洗衣粉除污更有效。
  • Among the enzymes which are particularly effective are pepsin, papain. 在酶当中特别有效的是胃朊酶、木瓜酶。
13 defense AxbxB     
n.防御,保卫;[pl.]防务工事;辩护,答辩
参考例句:
  • The accused has the right to defense.被告人有权获得辩护。
  • The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。
14 bacterium BN7zE     
n.(pl.)bacteria 细菌
参考例句:
  • The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
  • A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。
15 nutrient 3vpye     
adj.营养的,滋养的;n.营养物,营养品
参考例句:
  • Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
  • The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。
16 parasites a8076647ef34cfbbf9d3cb418df78a08     
寄生物( parasite的名词复数 ); 靠他人为生的人; 诸虫
参考例句:
  • These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的,而与寄生虫无关。
  • Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。
17 migration mDpxj     
n.迁移,移居,(鸟类等的)迁徙
参考例句:
  • Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
  • He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。
18 ecological IrRxX     
adj.生态的,生态学的
参考例句:
  • The region has been declared an ecological disaster zone.这个地区已经宣布为生态灾难区。
  • Each animal has its ecological niche.每种动物都有自己的生态位.
19 caterpillar ir5zf     
n.毛虫,蝴蝶的幼虫
参考例句:
  • A butterfly is produced by metamorphosis from a caterpillar.蝴蝶是由毛虫脱胎变成的。
  • A caterpillar must pass through the cocoon stage to become a butterfly.毛毛虫必须经过茧的阶段才能变成蝴蝶。
TAG标签: body genome human louse
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