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  3. Lonely people，it seems，are at greater risk than the gregarious of developing illnesses associated with chronic inflammation，such

Lonely people，it seems，are at greater risk than the gregarious of developing illnesses associated with chronic inflammation，such

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问题    Lonely people，it seems，are at greater risk than the gregarious of developing illnesses associated with chronic inflammation，such as heart disease and certain cancers．A paper published last year in the Public Library of Science，Medicine，shows the effect on mortality of loneliness is comparable with that of smoking and drinking after examining the results of 148 previous studies and controlled for factors such as age and pre-existing illness．
    Steven Cole of the University of California，Los Angeles，thinks he may know why this is so．He told the American Association for the Advancement of Science meeting in Washington，D．C．，about his work studying the expression of genes in lonely people．Dr．Cole harvested samples of white blood cells from both lonely and gregarious people．He then analysed the activity of their genes，as measured by the production of a substance called messenger RNA．This molecule carries instructions from the genes telling a cell which proteins to make．The level of messenger RNA from most genes was the same in both types of people．There were several dozen genes，however，that were less active in the lonely，and several dozen others that were more active．Moreover，both the less active and the more active gene types came from a small number of functional groups．
    Broadly speaking，the genes less active in the lonely were those involved in staving off viral infections．Those that were more active were involved in protecting against bacteria．Dr．Cole suspects this could help explain not only why the lonely are iller，but how，in evolutionary terms，this odd state of affairs has come about．
  The crucial bit of the puzzle is that viruses have to be caught from another infected individual and they aye usually species-specific．Bacteria，in contrast，often just lurk in the environment，and may thrive on many hosts．The gregarious are therefore at greater risk than the lonely of catching viruses，and Dr．Cole thus suggests that past evolution has created a mechanism which causes white cells to respond appropriately．Conversely，the lonely are better off ramping up their protection against bacterial infection，which is a bigger relative risk to them．
    What Dr．Cole seems to have revealed，then，is a mechanism by which social environment reaches inside a person’s body and tweaks its genome so that it responds appropriately．It is not that the lonely and the gregarious are genetically different from each other．Rather，their genes are regulated differently，according to how sociable an individual is．Dr．Cole thinks this regulation is part of a wider mechanism that tunes individuals to the circumstances they find themselves in．
Dr．Cole made an analysis of the activity of the genes by____________．
选项 A、measuring the level of messenger RNA
B、calculating the number of more active gene types
C、instructing the production of certain proteins
D、comparing less active genes with more active ones
答案A
解析 细节题。根据题干信息定位到第二段的第三、四句。从这两句可知，Cole博士从孤独的人和爱交际的人那里收集了白细胞样本，然后靠测量一种叫作信使RNA的物质的数量分析了他们基因的活性，或者说通过测量信使RNA的含量来分析基因活性，故A项符合题意，为正确答案。B、D两项在原文中没有提及，可排除。原文提到的是信使RNA携带者基因上的指令，这些指令告诉细胞生产哪类蛋白质，显然这是对信使RNA的介绍，并不是分析基因活性的方法，故C项“对生产某种蛋白质下达指令”错误。故本题选A。
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