A Whale of a Lifespan

Scientists have mapped the genetic code of this long-lived whale species. The international effort found unusual features in the Arctic whale's genes. Those features likely protect the species against cancer and other problems related to old age. The researchers hope their findings will one day translate into ways to help people too.

No other mammal is known to live as long as the bowhead. Scientists have shown that some of these whales have lived well beyond 100 - including one that survived to 211. For perspective， if he were still alive， Abraham Lincoln would be turning just 206 this year.

A team from University of Liverpool wanted to understand how the bowhead can live so long. To probe this， the experts analyzed the animal's complete set of genetic instructions， called its genome. Those instructions are coded in the animals DNA. The team also compared the whale's genome to those of people， mice and cows.

The scientists discovered differences， including mutations， in the whale's genes. Those changes are linked to cancer， aging and cell growth. The results suggest that the whales are better than humans at repairing their DNA. Thats important because damaged or flawed DNA can lead to diseases， including some cancers.

Bowheads also are better at keeping abnormally dividing cells in check. Together， the changes appear to allow bowhead whales to live longer without developing age-related diseases such as cancer， say the scientists.

鯨的壽命

科學(xué)家已經(jīng)繪制了長壽動物北極露脊鯨的基因密碼圖，各國研究者通過共同努力揭示了北極露脊鯨基因非同尋常的特征，這些特征很可能幫助該物種避免與老齡相關(guān)的癌癥和其他疾病。研究者希望，有朝一日他們的發(fā)現(xiàn)能服務(wù)于人類。

目前已知，北極露脊鯨是哺乳動物中壽命最長的?？茖W(xué)研究證實，有些北極露脊鯨的壽命大大超過了100歲，其中一頭活到了211歲。試想，亞伯拉罕·林肯如果在世的話，他今年也才206歲。

為了弄清北極露脊鯨的長壽秘訣，英國利物浦大學(xué)的一個研究團(tuán)隊分析了該動物的一整套遺傳指令，即基因組，這些指令以編碼的形式存在于動物的DNA中。研究團(tuán)隊還將鯨的基因組和人、老鼠、牛的基因組進(jìn)行了對比。

這些科學(xué)家在鯨體內(nèi)發(fā)現(xiàn)了一些有別于其他哺乳動物的差異，其中包括基因突變的差異。這些突變和癌癥、衰老、細(xì)胞生長相關(guān)。研究表明：與人相比，鯨更擅長修復(fù)DNA。這一點至關(guān)重要，因為損壞的、有缺陷的DNA會引起包括癌癥在內(nèi)的疾病。

北極露脊鯨也更擅長控制細(xì)胞的異常分裂?？茖W(xué)家們說，綜合各種因素，基因突變似乎是鯨不會罹患諸如癌癥之類的老年疾病從而獲得長壽的秘訣。

（注意斜體字的譯法）

Are Our Schools Damaging Children's Eyes？

Over the last 30 years， short sight， or myopia， has become a global （A） h problem. The most dramatic （1） r has been in Singapore， Taiwan， China's （B） c and elsewhere in East Asia. Rates can be as high as 80-90 per cent among children leaving secondary schools in the region. As many as a fifth of them have severe myopia and so are at high risk of eye problems in later life. In Western countries rates are increasing， although not as rapidly as in East Asia.

The cause of myopia， and the means to prevent it， are unclear despite more than 150 years of scientific （C） r . Many theories have been put forward to explain why children's （2） e gets worse as they go through school. Too much close work is one of the more popular ones， while heredity is another. Both have been hotly debated down the years.

Myopia， scientists find， is a seasonal condition which seems to get worse in the winter. Recent research on myopia has revived an old theory from the 1890s， that （3） s children who spend more time outdoors have lower levels of myopia. Low ambient light（環(huán)境光線）levels rather than low vitamin D levels seem to be the deciding （4）f in myopia.

A century ago， it was widely believed that high （D） d levels in schools could prevent myopia. Education departments built classrooms with large windows to try to stop children becoming short-sighted. Then in 1960s， medical thinking changed. Myopia was thought to be an inherited condition， so less was done to prevent it. Today， it is known that children's education has a far greater （5） i on their sight than genetic factors. Evidence that daylight in classrooms prevents myopia is lacking. "It has not been investigated properly since the connection was first made in the 1860s，" said the （E） a of this study Dr. Richard Hobday. "But， given the rapid increase in myopia among school children worldwide， this should be revisited."