文章注释
ONE difficulty faced by conservationists is getting hold of reliable statistics on the animals they are looking after. For good reason many species, particularly herbivores with a lot of predators, are rather shy. In tropical forests the problem is especially acute, since the dense jungle is perfect for hiding in. That makes it hard to know how well a given species is really doing.
自然资源保护论者面临的一大难题是如何获得他们所关心的物的相关可靠数据。对于许多物种，特别是那些有许多天敌的植食动物而言，合理地解释是它们比较胆小。此种现象在热带森林更为严重，因为稠密的丛林可谓是完美的藏身之处。这让研究特定物种的真实行为变得困难重重。
In a paper just published in Current Biology, though, a group of researchers led by Ida Baerholm Schnell, of Copenhagen Zoo, describe a clever, low-cost solution. Their idea is to take another well-known difficulty of doing fieldwork in tropical forests—the endless swarms of bloodsucking leeches—and turn it into a scientific tool.
根据《当代物学》一篇刚发表的论文，哥本哈根动物园的Ida Baerholm Schnell领导的一组研究人员描述了一种巧妙的、低成本的解决方法。他们设想将吸血水蛭变成科学工具，热带森林的野外研究当中，吸血水蛭也是另一大难题，他们成群结队，没完没了。
Leeches can go for months without food, surviving on blood stored from their last victim. Tipped off by a previous paper, which reported that viruses can survive inside blood sucked up by leeches for as long as half a year, Dr Schnell and her colleagues wondered if DNA from a leech’s most recent victim might be recoverable as well.
在没有进食的情况下，水蛭单凭最后一次吸食的血液贮存就可存活数月。根据先前报导，病毒可以在水蛭所吸收的血液中存活半年之久，受此启发，施耐德博士和他的同事猜测，水蛭最近吸食对象的DNA或许也可以被恢复。
To find out, they fed goat blood to 26 medicinal leeches, a catch-all term for various species still used, occasionally, by doctors. These were then killed one at a time at intervals over the next 141 days and the contents of their digestive tracts examined. Using a technique called the polymerase chain reaction, which employs enzymes to produce millions of copies of a DNA sequence, the researchers were able to prove that DNA from the goats survived in the leeches for at least four months.
为了证明这个猜测，研究人员用山羊的血喂养26只医用水蛭（这里泛指目前仍偶尔被医生使用的多种水蛭）。在接下来的141天内，每隔一段时间一只水蛭就会被杀掉，同时检测它们消化系统内的物质。通过运用聚合酶链式反应技术（利用DNA聚合酶来扩增已知的DNA片断的技术），研究人员证明了羊DNA可以在水蛭体内存活至少四个月。
Armed with this encouraging result, they moved on to trials in the jungles of Vietnam. They gathered 25 leeches (of a different species to the medicinal ones used in the previous study) and examined them for mammalian DNA. The results were impressive, including the first strong evidence for the presence of Nesolagus timminsi, a striped rabbit that ecologists had suspected lived in the area, but which had managed to evade more than 2,000 nights of camera surveillance. Its DNA was found inside four of the leeches tested. They also found genetic material from the Truong Son muntjac, a recently discovered small deer, and from the small-toothed ferret-badger, which is (apparently) impossible to distinguish from the related Burmese ferret-badger without getting close enough to handle it.
在这个鼓舞人的结果的指引下，研究人员转移到越南的丛林中继续试验。他们收集了25条蛭（与在之前研究中的医用水蛭不同），并用它们测试哺乳动物DNA。结果令人欣喜，试验第一次强有力地证明了一种身上带有条纹的野兔即斑纹兔的存在，生态学家早就怀疑它们生存在这个区域，但是它们却成功的躲避了超过2000多台夜晚照相机的监视。斑纹兔的DNA在四条蛭的体内被检测出来。研究人员同样发现了长山麂的遗传物质——长山麂是最近才被发现的一种小鹿。此外，小齿鼬獾的遗传物质也被发现，小齿鼬獾和缅甸鼬獾具有种属关系，如果不近距离仔细比较，只看外表是不可能将它们区分开来的。
At this stage, the study is only a proof of concept. A proper survey would require a great deal of systematic observation. It would also have to take into account the hunting patterns of the leeches, which may prefer to exsanguinate some animals more than others. But there are lots of potential benefits. The technique is cheap, and requires minimal training. The researchers note dryly that leeches are perfect for the task, because of “their diverse prey base” and “their readiness to attack humans”. In other words, you don’t even have to go looking for the biodiversity—it will attempt to wriggle down your socks all by itself.
现阶段，这项研究只是一个概念上的验证。一个真正的调查需要大量的系统观察。同样需要考虑在内的包括水蛭的狩猎方式，它们或许倾向于吸取某些动物的血而不是其他动物。但是这种方法也有很多潜在利益。此项技术成本很低而且需要很少训练即可。研究人员确定的描述水蛭是此项任务的最佳选择，因为它们猎物广泛且喜好攻击人类。换言之，你甚至都不用自己去寻找这种包含生物多样性的物种，水蛭们自然会爬进你的袜子里。
动物计数——用血液记录
更新于2015年06月29日
来源于原版英语
ONE difficulty faced by conservationists is getting hold of reliable statistics on the animals they are looking after. For good reason many species, particularly herbivores with a lot of predators, are rather shy. In tropical forests the problem is especially acute, since the dense jungle is perfect for hiding in. That makes it hard to know how well a given species is really doing.
自然资源保护论者面临的一大难题是如何获得他们所关心的物的相关可靠数据。对于许多物种，特别是那些有许多天敌的植食动物而言，合理地解释是它们比较胆小。此种现象在热带森林更为严重，因为稠密的丛林可谓是完美的藏身之处。这让研究特定物种的真实行为变得困难重重。
In a paper just published in Current Biology, though, a group of researchers led by Ida Baerholm Schnell, of Copenhagen Zoo, describe a clever, low-cost solution. Their idea is to take another well-known difficulty of doing fieldwork in tropical forests—the endless swarms of bloodsucking leeches—and turn it into a scientific tool.
根据《当代物学》一篇刚发表的论文，哥本哈根动物园的Ida Baerholm Schnell领导的一组研究人员描述了一种巧妙的、低成本的解决方法。他们设想将吸血水蛭变成科学工具，热带森林的野外研究当中，吸血水蛭也是另一大难题，他们成群结队，没完没了。
Leeches can go for months without food, surviving on blood stored from their last victim. Tipped off by a previous paper, which reported that viruses can survive inside blood sucked up by leeches for as long as half a year, Dr Schnell and her colleagues wondered if DNA from a leech’s most recent victim might be recoverable as well.
在没有进食的情况下，水蛭单凭最后一次吸食的血液贮存就可存活数月。根据先前报导，病毒可以在水蛭所吸收的血液中存活半年之久，受此启发，施耐德博士和他的同事猜测，水蛭最近吸食对象的DNA或许也可以被恢复。
To find out, they fed goat blood to 26 medicinal leeches, a catch-all term for various species still used, occasionally, by doctors. These were then killed one at a time at intervals over the next 141 days and the contents of their digestive tracts examined. Using a technique called the polymerase chain reaction, which employs enzymes to produce millions of copies of a DNA sequence, the researchers were able to prove that DNA from the goats survived in the leeches for at least four months.
为了证明这个猜测，研究人员用山羊的血喂养26只医用水蛭（这里泛指目前仍偶尔被医生使用的多种水蛭）。在接下来的141天内，每隔一段时间一只水蛭就会被杀掉，同时检测它们消化系统内的物质。通过运用聚合酶链式反应技术（利用DNA聚合酶来扩增已知的DNA片断的技术），研究人员证明了羊DNA可以在水蛭体内存活至少四个月。
Armed with this encouraging result, they moved on to trials in the jungles of Vietnam. They gathered 25 leeches (of a different species to the medicinal ones used in the previous study) and examined them for mammalian DNA. The results were impressive, including the first strong evidence for the presence of Nesolagus timminsi, a striped rabbit that ecologists had suspected lived in the area, but which had managed to evade more than 2,000 nights of camera surveillance. Its DNA was found inside four of the leeches tested. They also found genetic material from the Truong Son muntjac, a recently discovered small deer, and from the small-toothed ferret-badger, which is (apparently) impossible to distinguish from the related Burmese ferret-badger without getting close enough to handle it.
在这个鼓舞人的结果的指引下，研究人员转移到越南的丛林中继续试验。他们收集了25条蛭（与在之前研究中的医用水蛭不同），并用它们测试哺乳动物DNA。结果令人欣喜，试验第一次强有力地证明了一种身上带有条纹的野兔即斑纹兔的存在，生态学家早就怀疑它们生存在这个区域，但是它们却成功的躲避了超过2000多台夜晚照相机的监视。斑纹兔的DNA在四条蛭的体内被检测出来。研究人员同样发现了长山麂的遗传物质——长山麂是最近才被发现的一种小鹿。此外，小齿鼬獾的遗传物质也被发现，小齿鼬獾和缅甸鼬獾具有种属关系，如果不近距离仔细比较，只看外表是不可能将它们区分开来的。
At this stage, the study is only a proof of concept. A proper survey would require a great deal of systematic observation. It would also have to take into account the hunting patterns of the leeches, which may prefer to exsanguinate some animals more than others. But there are lots of potential benefits. The technique is cheap, and requires minimal training. The researchers note dryly that leeches are perfect for the task, because of “their diverse prey base” and “their readiness to attack humans”. In other words, you don’t even have to go looking for the biodiversity—it will attempt to wriggle down your socks all by itself.
现阶段，这项研究只是一个概念上的验证。一个真正的调查需要大量的系统观察。同样需要考虑在内的包括水蛭的狩猎方式，它们或许倾向于吸取某些动物的血而不是其他动物。但是这种方法也有很多潜在利益。此项技术成本很低而且需要很少训练即可。研究人员确定的描述水蛭是此项任务的最佳选择，因为它们猎物广泛且喜好攻击人类。换言之，你甚至都不用自己去寻找这种包含生物多样性的物种，水蛭们自然会爬进你的袜子里。
推荐阅读