Unit 5 Why genes aren’t destiny為什么基因不是命運 ——《21世紀研究生英語教材閱讀教程》下冊

1、unit 5 why genes arent destiny為什么基因不是命運the remote, snow-swept expanses of northern sweden are an unlikely place to begin a story about cutting-edge genetic science. the kingdoms northernmost county, norrbotten, is nearly free of human life; an average of just six people live in each square mile. and

2、 yet this tiny population can reveal a lot about how genes work in our everyday lives.1. 偏遠，白雪皚皚的瑞典北部區(qū)域不像是一個關于最前沿的基因科學的故事開始的地方。北博滕是這片區(qū)域最北部的一個鎮(zhèn)，那兒人煙稀少，每平方公里平均只有兩人居住。然而如此稀少的人口卻大大揭示了基因在我們日常生活中的作用。norrbotten is so isolated that in the 19th century, if the harvest was bad, people starved. the starving ye

3、ars were all the crueler for their unpredictability. for instance, 1800, 1812, 1821, 1836 and 1856 were years of total crop failure and extreme suffering. but in 1801, 1822, 1828, 1844 and 1863, the land spilled forth such abundance that the same people who had gone hungry in previous winters were a

4、ble to gorge themselves for months.2. 北博滕是如此的與世隔絕以至于在十九世紀時，如果收成不好，人們就只能挨餓。由于其不可預測，饑餓的年成便更加恐怖。例如，1800，1812，1821，1836 和1856都是顆粒無收，民不聊生的年份。但在1801，1822，1828，1844及1863年，土地產出了如此豐沛的糧食以至于頭年挨餓的人們可以連續(xù)數(shù)月大吃特吃。in the 1980s, dr. lars olov bygren, a preventive-health specialist who is now at the prestigious karoli

5、nska institute in stockholm, began to wonder what long-term effects the feast and famine years might have had on children growing up in norrbotten in the 19th century and not just on them but on their kids and grandkids as well. so he drew a random sample of 99 individuals born in the overkalix pari

6、sh of norrbotten in 1905 and used historical records to trace their parents and grandparents back to birth. by analyzing meticulous agricultural records, bygren and two colleagues determined how much food had been available to the parents and grandparents when they were young.3. 拉爾夫 歐勒 拜格倫博士是一位預防醫(yī)學專

7、家，現(xiàn)任職于聲名顯赫的位于斯德哥爾摩的卡羅林斯卡學院。從二十世紀八十年代起，他開始研究豐收和饑餓的年份對十九世紀的北博滕孩子的成長的長期影響-不僅這些孩子，還有這些孩子的孩子以及孫輩。他隨機抽取了生于1905年的北博滕奧佛卡利克斯教區(qū)的99個孩子作為研究對象。通過歷史記錄，他追蹤到了這些孩子的父母和祖父母的生平。通過仔細分析農業(yè)生產記錄，拜格倫和兩個同事能夠計算出那些父母和祖父母年輕時的食物有多少。around the time he started collecting the data, bygren had become fascinated with research showing

8、that conditions in the womb could affect your health not only when you were a fetus but well into adulthood. in 1986, for example, the lancet published the first of two groundbreaking papers showing that if a pregnant woman ate poorly, her child would be at significantly higher than average risk for

9、 cardiovascular disease as an adult. bygren wondered whether that effect could start even before pregnancy: could parents experiences early in their lives somehow change the traits they passed to their offspring?4. 研究表明，子宮內的環(huán)境不僅對胎兒健康有影響，這種影響甚至能夠持續(xù)到一個人的成年期。拜格倫對這一研究產生了極大的興趣，他開始收集相關數(shù)據(jù)。例如，柳葉刀雜志在1986年首次發(fā)

10、表了兩篇具有突破性意義的文章，文中稱，如果一個懷孕的婦女營養(yǎng)不良，那么她的孩子在成年后患心血管疾病的風險將遠高于平均水平。拜格倫想知道，這種影響是否在孕期前就開始了，即：父母早期的生活經(jīng)歷是否會改變他們遺傳給下一代的特征？it was a heretical idea. after all, we have had a long-standing deal with biology: whatever choices we make during our lives might ruin our short-term memory or make us fat or hasten death,

11、 but they wont change our genes our actual dna. which meant that when we had kids of our own, the genetic slate would be wiped clean.5. 這在當時是一個異端邪說的想法。畢竟，我們在生物學上有一個長期存在的觀念，即：無論我們在生活中做出怎樣的選擇，都只能毀壞我們的短期記憶，或者使我們發(fā)胖，或加速我們的死亡，但是那些選擇將不會改變我們的基因我們的脫氧核糖核酸（dna）結構。也就是說，當我們有了我們自己的孩子，我們的基因表又能恢復如常。whats more, any

12、such effects of nurture (environment) on a species nature (genes) were not supposed to happen so quickly. charles darwin, whose on the origin of species celebrated its 150th anniversary in november, taught us that evolutionary changes take place over many generations and through millions of years of

13、 natural selection. but bygren and other scientists have now amassed historical evidence suggesting that powerful environmental conditions (near death from starvation, for instance) can somehow leave an imprint on the genetic material in eggs and sperm. these genetic imprints can short-circuit evolu

14、tion and pass along new traits in a single generation.6. 并且我們以為養(yǎng)育（環(huán)境）對一個物種的天性（基因）的任何影響都不可能這么快地體現(xiàn)出來。查爾斯 達爾文的物種起源到今年十一月已發(fā)表了150周年，它告訴我們漸進式變革的發(fā)生需要許多代人的時間并且是幾百萬年自然選擇的結果。但是拜格倫和其他科學家現(xiàn)在已經(jīng)積累了歷史證據(jù)來證明，強大的環(huán)境因素（例如由于饑餓而瀕臨死亡）能夠在卵子和精子的基因物質上留下痕跡。這些基因痕跡能暫時中斷進化并在下一代人身上留下新的特征。for instance, bygrens research showed that

15、in overkalix, boys who enjoyed those rare overabundant winters kids who went from normal eating to gluttony in a single season produced sons and grandsons who lived shorter lives. far shorter: in the first paper bygren wrote about norrbotten, which was published in 2001 in the dutch journal acta bio

16、theoretica, he showed that the grandsons of overkalix boys who had overeaten died an average of six years earlier than the grandsons of those who had endured a poor harvest. once bygren and his team controlled for certain socioeconomic variations, the difference in longevity jumped to an astonishing

17、 32 years. later papers using different norrbotten cohorts also found significant drops in life span and discovered that they applied along the female line as well, meaning that the daughters and granddaughters of girls who had gone from normal to gluttonous diets also lived shorter lives. to put it

18、 simply, the data suggested that a single winter of overeating as a youngster could initiate a biological chain of events that would lead ones grandchildren to die decades earlier than their peers did. how could this be possible?7. 例如，拜格倫的研究表明，在奧佛卡利克斯教區(qū)，那些享受了過于豐盛的冬季的男孩（在同一季節(jié)中經(jīng)歷了從正常飲食到暴飲暴食的孩子），他們的子輩和

19、孫輩壽命比其他人更短。拜格倫第一篇關于北博滕的論文發(fā)表于2001年的荷蘭期刊acta biotheoretica 上，在這篇文章中他提到，生活在奧佛卡利克斯教區(qū)的有過度飲食經(jīng)歷男孩的孫輩比經(jīng)歷了收成很差的男孩的孫輩平均壽命短六年。當拜格倫和他的研究小組控制了社會經(jīng)濟方面的其他變量，這一壽命差距就上升到令人震驚的32年。此后的論文研究了北博滕另一些孩子，結果同樣發(fā)現(xiàn)了明顯的壽命下降，并且這一結果也適用于女性，即經(jīng)歷了從正常飲食到暴飲暴食的女孩的子輩和孫輩壽命比其他人更短。簡言之，數(shù)據(jù)顯示一個過度飲食的冬季會啟動一連串的生物連鎖反應，其結果是，一個人的孫輩比其他人的孫輩的壽命短幾十年。這是怎樣發(fā)生

20、的呢？meet the epigenome認識表觀基因組the answer lies beyond both nature and nurture. bygrens data along with those of many other scientists working separately over the past 20 years have given birth to a new science called epigenetics. at its most basic, epigenetics is the study of changes in gene activity t

21、hat do not involve alterations to the genetic code but still get passed down to at least one successive generation. these patterns of gene expression are governed by the cellular material the epigenome that sits on top of the genome, just outside it (hence the prefix epi-, which means above). it is

22、these epigenetic marks that tell your genes to switch on or off, to speak loudly or whisper. it is through epigenetic marks that environmental factors like diet, stress and prenatal nutrition can make an imprint on genes that is passed from one generation to the next.8. 答案不在天生和養(yǎng)育。拜格倫的研究數(shù)據(jù)以及過去20年間許多在

23、此領域做了獨立研究的科學家們的成果催生了一門叫表觀遺傳學的新學科。究其根本，表觀遺傳學是一門研究基因活動中產生的變化的學科，這種變化雖不使基因碼產生變異但還是會影響接下來的至少一代人。這種基因表達的模式由一種叫表觀基因組的細胞物質控制，表觀基因組在基因組之上，就在其表層（這一點我們從表觀基因組這個單詞的前綴就可得知）。正是這些表觀遺傳“標記”告訴你的基因打開或關閉，大聲說話或低聲細語。通過這些表觀遺傳標記，諸如飲食，壓力和產前營養(yǎng)等環(huán)境因素能在基因上留下印記并傳給接下來的一代人。epigenetics brings both good news and bad. bad news first:

24、 theres evidence that lifestyle choices like smoking and eating too much can change the epigenetic marks atop your dna in ways that cause the genes for obesity to express themselves too strongly and the genes for longevity to express themselves too weakly. we all know that you can truncate your own

25、life if you smoke or overeat, but its becoming clear that those same bad behaviors can also predispose your kids before they are even conceived to disease and early death.9. 表觀遺傳學研究給我們同時帶來了好消息和壞消息。先說壞消息：抽煙和過度飲食等生活方式上的選擇能通過一些方式改變你的脫氧核糖核酸上的表觀遺傳標記，例如，使肥胖基因過于強烈地表達或使長壽基因表達過于無力。我們都知道，如果你吸煙或飲食過量，你的壽命將縮短，但是

26、，現(xiàn)在我們了解到，這些壞習慣也能使你的孩子（甚至在他們出生前就注定要）生病或早亡。the good news: scientists are learning to manipulate epigenetic marks in the lab, which means they are developing drugs that treat illness simply by silencing bad genes and jump-starting good ones. in 2004 the food and drug administration (fda) approved an ep

27、igenetic drug for the first time. azacitidine is used to treat patients with myelodysplastic syndromes (usually abbreviated, a bit oddly, to mds), a group of rare and deadly blood malignancies. the drug uses epigenetic marks to dial down genes in blood precursor cells that have become overexpressed.

28、 according to celgene corp. the summit, n.j., company that makes azacitidine people given a diagnosis of serious mds live a median of two years on azacitidine; those taking conventional blood medications live just 15 months.10. 好消息是：科學家們正在實驗室里學習操縱表觀遺傳標記，這意味著他們在研發(fā)能夠通過使壞基因噤聲和啟動好基因的方式來治病的藥物。2004年，美國食品與

29、藥物監(jiān)管局首次批準了一種表觀遺傳藥物的上市。阿扎胞苷被用于治療脊髓增生異常綜合癥患者（脊髓增生異常綜合癥是罕見而又致命的血液惡性腫瘤）。此藥物利用表觀遺傳標記來抑制過度表達的血液前體細胞。據(jù)阿扎胞苷生產商的數(shù)據(jù)，在被診斷出患有嚴重脊髓增生異常綜合癥的患者當中，服用阿扎胞苷的患者能存活兩年，而服用傳統(tǒng)藥物的人只能存活15個月。since 2004, the fda has approved three other epigenetic drugs that are thought to work at least in part by stimulating tumor-suppressor g

30、enes that disease has silenced. the great hope for ongoing epigenetic research is that with the flick of a biochemical switch, we could tell genes that play a role in many diseases including cancer, schizophrenia, autism, alzheimers, diabetes and many others to lie dormant. we could, at long last, h

31、ave a trump card to play against darwin.11. 自從2004年以來，美國食品與藥物監(jiān)管局已經(jīng)批準了三種表觀遺傳藥物的上市，這些藥物被認為能在一定程度上刺激那些受疾病影響沒有正常表達的腫瘤抑制基因。對于不斷進行的表觀遺傳學研究，我們寄予重望，希望能輕扣生化開關，便能使那些在許多疾病中（如，癌癥，精神分裂癥，自閉癥，老年癡呆癥，糖尿病，等等）發(fā)揮作用的基因沉睡。這樣，我們最終就能有一張打敗達爾文的王牌。the funny thing is, scientists have known about epigenetic marks since at least

32、 the 1970s. but until the late 90s, epigenetic phenomena were regarded as a sideshow to the main event, dna. to be sure, epigenetic marks were always understood to be important: after all, a cell in your brain and a cell in your kidney contain the exact same dna, and scientists have long known that

33、nascent cells can differentiate only when crucial epigenetic processes turn on or turn off the right genes in utero.12. 有意思的是，科學家們自二十世紀七十年代以來就對表觀遺傳標記有所了解，但在二十世紀九十年代后期之前，表觀遺傳現(xiàn)象一直被當作是dna這一主要事件的小插曲。確切地說，表觀遺傳標記從來被認為是重要的，畢竟，你的腦細胞和你的腎臟細胞包含完全相同的dna，只有當至關重要的表觀遺傳程序在子宮里打開或關閉正確的基因，初生細胞才能辨別他們。more recently, however, researchers have begun to realize that epigenetics could also help explain certain scientific mysteries