英语听力文摘 DNA帮助捕获偷猎者
DNA Helps Catch Poachers
科学家们利用一种革命性的基因技术成功确定了走私犯屠宰大象的非洲地区，这些大象沦为全世界非法象牙贸易的受害者。利用非洲大象的DNA图谱，他们已发现最近缉获的象牙来自坦桑尼亚和莫桑比克边界的塞卢斯及尼亚萨两个禁猎区的大象。这一发现表明，应对世界上大部分日益猖獗的非法象牙贸易以及每年遭到屠杀的成千上万头大象负责的，只是少数卡特尔组织。最近在台湾、香港、越南、菲律宾和日本分别独立发起的码头突击搜查中缉获了数以千计的象牙，这揭示了这种非法贸易的严重程度。这些象牙都是为了满足远东日益增长的象牙需求，象牙成为该区域日益膨胀的工业化经济体中中产阶级社会地位的新象征。因此，象牙价格已从2004年每公斤200美元飙升到了每公斤6,000多美元。与此同时，科学家们估计，目前每年有8%至10%的非洲大象正在遭到捕杀以满足市场需求。
Find out how DNA can help catch poachers, on this Moment of Science.
The OJ Simpson trial put DNA testing as a forensics(辩论术) tool in the spotlight. Now DNA’s use in identifying criminals is nothing new, but what is new is its use to identify a different kind of criminal–elephant poachers.
In the 1980’s, the number of African elephants dropped from 1.3 million to about 500,000. In order to protect the elephants, an international ban(禁令) on the selling of African ivory was implemented(实施), but that didn’t stop poachers.
One difficulty law enforcers(实施者) face in tracking(跟踪) poachers is that it’s difficult to know where exactly (2)poaching(非法猎取) is most concentrated(集中的). That’s where DNA testing comes in.
There are two different species of African elephant, savanna(热带草原) elephants, which inhabit the grassy(长满草的) plains and bushland(原始林区), and forest elephants, which live in the equatorial(赤道的) forests. DNA testing can distinguish not only the ivory of savanna elephants from that of forest elephants, but it can to a large degree (3)decipher(解释) what region an elephant comes from.
All that genetic testing requires is a small sample from the core of an elephant tusk(长牙), about the size of a kernel(核心，要点) of corn. Ivory tusks are teeth, and they’re made of a material called dentin(象牙质). Because dentin is secreted(分泌) by cells in the jaws, scientists predicted that DNA from these cells might be found inside the dentin.
They did indeed find DNA in the tusks and by comparing it to a database of elephants from across the continent of Africa, they’ve been able to locate where the elephant comes from. This enables law enforcers to concentrate their efforts in regions where poaching is most threatening(危险的). It’s yet another example of DNA’s use in solving crimes.
Notes:
(1)forensics [f?'rensiks] n. 辩论术;辩论练
Computer Forensics in the fight against computer crime and network in a very critical role.
计算机取证在打击计算机和网络犯罪中作用十分关键。
(2)poach [p?ut?] vt.水煮;偷猎;窃取;把…踏成泥浆 vi.偷猎;侵犯;剽窃
1.A new political party usually poach idea from its rival.
新政党往往把敌对政党的思想攫为己有。
2.I stole his bride. I guess it's OK to poach the florist.
我偷了他的新娘，我想把他的花商偷来应该没问题吧。
(3)decipher[di'saif?] n. 密电译文 vt.解释，译解
1.Several African universities now have programmes to decipher the paintings and carvings.
现在几所非洲的大学有解译些绘画和雕刻的项目。
2.Geneticists have yet to decipher the complex code by which epigenetic marks interact with the other components of the genome.
目前，遗传学家还未破解外遗传标签与基因组其他组成之间，产生互动的复杂编码。
