文章来源:未知 文章作者:meng 发布时间:2009-10-23 06:02 字体: [ ]  进入论坛

Scientists have unravelled1 the mechanism2 by which the fungal disease chytridiomycosis kills its victims.


A world of <a href=amphibians4" width="226" border="0" src="/upimg/091023/4_062840_1.jpg" />
A world of amphibians

The fungus5(真菌,霉菌) is steadily6 spreading through populations of frogs and other amphibians(两栖类) worldwide, and has sent some species extinct in just a few years.

Researchers now report in the journal Science that the fungus kills by changing the animals' electrolyte balance(电解质平衡), resulting in cardiac arrest(心搏停止).

The finding is described as a "key step" in understanding the epidemic7(传染病,流行病).

Karen Lips, one of the world authorities on the spread of chytridiomycosis(油彩蛙), said the research was "compelling(令人注目的,强制的)".

"They've done an incredible amount of work, been very thorough, and I don't think anybody will have problems with this.

"We suspected something like this all along, but it's great to know this is in fact what is happening," the University of Maryland professor told BBC News.

Skin deep

Amphibian3 skin plays several roles in the animals' life.

Most species can breathe through it, and it is also used as a membrane8(薄膜,羊皮纸) through which electrolytes such as sodium9(钠) and potassium(钾) are exchanged with the outside world.

The mainly Australian research group took skin samples from healthy and diseased green tree frogs, and found that these compounds passed through the skin much less readily when chytrid(壶菌) was present.

Samples of blood and urine from infected frogs showed much lower sodium and potassium concentrations than in healthy animals - potassium was down by half.

In other animals including humans, this kind of disturbance10 is known to be capable of causing cardiac arrest.

The scientists also took electrocardiogram recordings11 of the frogs' hearts in the hours before death; and found changes to the rhythm culminating(终极的,最后的) in arrest.

Drugs that restore electrolyte balance brought the animals a few hours or days of better health, some showing enough vigour12(精力) to climb out of their bowls of water; but all died in the end.

Grail quest

Lead scientist Jamie Voyles, from James Cook University in Townsville, said the next step was to look for the same phenomenon in other species.

"This is lethal13 across a broad range of hosts, whether terrestrial(地球的,地上的) or aquatic14(水生的,水中的), so it's really important to look at what's happening in other susceptible15(易受影响的) amphibians," she said.

Another step will be to examine how the chytrid fungus (Batrachochytrium dendrobatidis - Bd) impairs16 electrolyte transfer.

"What this work doesn't tell us is the mechanism by which chytrid causes this problem with sodium," said Matthew Fisher from Imperial College London.

"It could be that Bd is excreting a toxin17, or it could be causing cell damage. This causative action is actually the 'holy grail' - so that's another obvious next step."

The finding is unlikely to plot an immediate18 route to ways of preventing or treating or curing the disease in the wild.

Curing infected amphibians in captivity19 is straightforward20 using antifungal(抗真菌的) chemicals; but currently there is no way to tackle it outside.

Various research teams are exploring the potential of bacteria that occur naturally on the skin of some amphibians, and may play a protective role.

Understanding the genetics of how Bd disrupts electrolyte balance might lead to more precise identification of protective bacteria, suggested Professor Lips, and so eventually play a role in curbing21 the epidemic.


1 unravelled 596c5e010a04f9867a027c09c744f685     
解开,拆散,散开( unravel的过去式和过去分词 ); 阐明; 澄清; 弄清楚
  • I unravelled the string and wound it into a ball. 我把绳子解开并绕成一个球。
  • The legal tangle was never really unravelled. 这起法律纠葛从来没有真正解决。
2 mechanism zCWxr     
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
3 amphibian mwHzx     
  • The frog is an amphibian,which means it can live on land and in water.青蛙属于两栖动物,也就是说它既能生活在陆地上也能生活在水里。
  • Amphibian is an important specie in ecosystem and has profound meaning in the ecotoxicology evaluation.两栖类是生态系统中的重要物种,并且对环境毒理评价有着深远意义。
4 amphibians c4a317a734a700eb6f767bdc511c1588     
两栖动物( amphibian的名词复数 ); 水陆两用车; 水旱两生植物; 水陆两用飞行器
  • The skin of amphibians is permeable to water. 两栖动物的皮肤是透水的。
  • Two amphibians ferry them out over the sands. 两辆水陆两用车把他们渡过沙滩。
5 fungus gzRyI     
  • Mushrooms are a type of fungus.蘑菇是一种真菌。
  • This fungus can just be detected by the unaided eye.这种真菌只用肉眼就能检查出。
6 steadily Qukw6     
  • The scope of man's use of natural resources will steadily grow.人类利用自然资源的广度将日益扩大。
  • Our educational reform was steadily led onto the correct path.我们的教学改革慢慢上轨道了。
7 epidemic 5iTzz     
  • 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。
8 membrane H7ez8     
  • A vibrating membrane in the ear helps to convey sounds to the brain.耳膜的振动帮助声音传送到大脑。
  • A plastic membrane serves as selective diffusion barrier.一层塑料薄膜起着选择性渗透屏障的作用。
9 sodium Hrpyc     
  • Out over the town the sodium lights were lit.在外面,全城的钠光灯都亮了。
  • Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。
10 disturbance BsNxk     
  • He is suffering an emotional disturbance.他的情绪受到了困扰。
  • You can work in here without any disturbance.在这儿你可不受任何干扰地工作。
11 recordings 22f9946cd05973582e73e4e3c0239bb7     
n.记录( recording的名词复数 );录音;录像;唱片
  • a boxed set of original recordings 一套盒装原声录音带
  • old jazz recordings reissued on CD 以激光唱片重新发行的老爵士乐
12 vigour lhtwr     
  • She is full of vigour and enthusiasm.她有热情,有朝气。
  • At 40,he was in his prime and full of vigour.他40岁时正年富力强。
13 lethal D3LyB     
  • A hammer can be a lethal weapon.铁锤可以是致命的武器。
  • She took a lethal amount of poison and died.她服了致命剂量的毒药死了。
14 aquatic mvXzk     
  • Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
  • We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。
15 susceptible 4rrw7     
  • Children are more susceptible than adults.孩子比成人易受感动。
  • We are all susceptible to advertising.我们都易受广告的影响。
16 impairs 866bc0da43dd90e04b6073750ff1e87c     
v.损害,削弱( impair的第三人称单数 )
  • Smoking impairs our health. 吸烟会损害我们的健康。 来自《简明英汉词典》
  • Almost anything that impairs liver function can cause hepatitis. 任何有损于肝功能的因素,几乎都会引起肝炎。 来自辞典例句
17 toxin hn5wb     
  • Experts have linked this condition to a build-up of toxins in the body.专家已把这一病症与体内毒素的积累联系起来。
  • Tests showed increased levels of toxin in shellfish.检验表明水生有壳动物的毒素水平提高了。
18 immediate aapxh     
  • His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
  • We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。
19 captivity qrJzv     
  • A zoo is a place where live animals are kept in captivity for the public to see.动物园是圈养动物以供公众观看的场所。
  • He was held in captivity for three years.他被囚禁叁年。
20 straightforward fFfyA     
  • A straightforward talk is better than a flowery speech.巧言不如直说。
  • I must insist on your giving me a straightforward answer.我一定要你给我一个直截了当的回答。
21 curbing 8c36e8e7e184a75aca623e404655efad     
n.边石,边石的材料v.限制,克制,抑制( curb的现在分词 )
  • Progress has been made in curbing inflation. 在控制通货膨胀方面已取得了进展。
  • A range of policies have been introduced aimed at curbing inflation. 为了抑制通货膨胀实施了一系列的政策。