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Science and technology
科學(xué)技術(shù)
Epigenetics and health
表觀遺傳學(xué)與健康
Grandma's curse
祖母的詛咒
Some of the effects of smoking may be passed from grandmother to grandchild
祖母吸煙產(chǎn)生的影響可以會遺傳至孫子或?qū)O女
Think of your grandchildren!
想想你的孫輩吧！
ONE of biology's hottest topics is epigenetics.
當(dāng)今生物學(xué)最熱的話題之一是表觀遺傳學(xué)，
The term itself covers a multitude of sins.
這個術(shù)語本身就涵蓋了許多宗罪。
Strictly speaking, it refers to the regulation of gene expression by the chemical modification of DNA, or of the histone proteins in which DNA is usually wrapped.
嚴格來說，表觀遺傳學(xué)研究的是DNA或含有DNA的組蛋白化學(xué)改性中的基因表達調(diào)控現(xiàn)象。
This modification is either the addition of methyl groups to the DNA or of acetyl groups to the histones.
這種改性或者是甲基增至DNA中，或者是乙酰基增加到組蛋白中。
Methylation switches genes off.
甲基化作用關(guān)閉基因，
Acetylation switches them on.
乙酰化作用啟動基因。
Since, in a multicellular organism, different cells need different genes to be active, such regulation is vital.
由于在多細胞有機體中，不同的細胞需要借助不同的基因以激活自身，所以這種調(diào)控至關(guān)重要。
What has got a lot of people excited, though, is the idea that epigenetic switches might be transmitted down the generations.
但令人興奮的是，有觀點認為，表觀遺傳現(xiàn)象中的基因表達調(diào)控功能有可能世代相傳。
Some see this as contrary to Darwinism, since it would permit characteristics acquired during an organism's lifetime to be passed on to its offspring, as suggested by a rival theory of evolution put forward by Jean-Baptiste Lamarck.
有些人將之視為對達爾文學(xué)說的反證，因為這將允許有機體存活期間所獲得的特征遺傳給后代，正如法國著名生物學(xué)家讓巴蒂斯特拉馬克所提出的與進化論相對的學(xué)說。
This is an exaggeration.
這種想法有些夸張了。
The DNA sequence itself is not being permanently altered.
基因序列不會一直變化，
Even those epigenetic changes that are inherited seem to be subsequently reversible.
甚至那些表觀遺傳學(xué)意義上的變化遺傳給下一代后，似乎仍然存在可逆性。
But the idea that acquired characteristics can be inherited at all is still an important and novel one, and a worrying example of the phenomenon has been published this week in BioMed Central Medicine.
但是，因表觀遺傳現(xiàn)象所獲得的特征完全可以遺傳的觀點仍然新穎且重要。本周，BioMed Central Medicine刊出了一項研究，可例證這一現(xiàn)象，其結(jié)果令人擔(dān)憂。
The study in question, by Virender Rehan of the Los Angeles Biomedical Research Institute, and his colleagues, was of the intergenerational effects of nicotine.
該項研究是由洛杉磯生物醫(yī)學(xué)研究所的Virender Rehan和他的同事們開展的，研究的是尼古丁的代際影響。
It was done in rats, but a rat's physiology is sufficiently similar to a human's to suspect the same thing may be true in Homo sapiens.
研究人員雖然在大鼠身上進行實驗，但因為大鼠的生理機能與人類十分相像，所以研究人員懷疑對于大鼠的研究結(jié)果可能同樣適用于智人。
In a nutshell, Dr Rehan showed that if pregnant rats are exposed to nicotine, not only will their offspring develop the asthma induced by this drug, so will the offspring of those offspring.
簡而言之，Rehan博士想說明的是，如果大鼠懷孕時接觸尼古丁，不僅下一代會因此患上哮喘，第三代也會深受其害。
Dr Rehan and his team injected their rats with nicotine when they were six days pregnant.
Rehan博士和他的團隊在大鼠懷孕的第六天為其注射尼古丁。
They then allowed them to give birth and raised the pups to the age of three weeks, before some were examined.
大鼠的后代出生后，由母鼠養(yǎng)育三周。
The rest were allowed to mature and breed, and their own offspring were similarly examined.
然后研究人員選取一部分后代進行檢查，其余的第二代大鼠繼續(xù)生長繁殖，最后研究人員對第三代大鼠進行類似的檢驗。
There was, however, no further administration of nicotine.
但是，第二代大鼠在妊娠期間，不再被注射尼古丁。
The pups of the treated mothers had asthmatic lungs.
檢測發(fā)現(xiàn)，被注射尼古丁的母鼠所繁殖的第二代大鼠肺部有哮喘病變。
The organs' airways were constricted,
大鼠肺部的氣道處于收縮狀態(tài)。
and molecular analysis showed abnormally high levels of fibronectin and collagen—which would stiffen the lung tissue—and also high levels of receptor molecules for nicotine.
經(jīng)過分子分析發(fā)現(xiàn)，大鼠肺部的纖維連接蛋白和膠原蛋白含量異常升高，這將導(dǎo)致肺組織硬化；同時尼古丁受體分子增加。
That was expected, since the developing embryos were exposed to the nicotine when their mothers were treated.
結(jié)果表明，母鼠被注射尼古丁后，其后代在胚胎發(fā)育時期就會受尼古丁的影響，這一結(jié)果正如預(yù)期。
However, when the team did similar tests on the grand-offspring of the treated mothers, they got similar results.
但是，當(dāng)研究團隊對第三代大鼠進行類似檢查時，發(fā)現(xiàn)了同樣的情況，
Those grand-offspring had not been exposed to nicotine.
即使這些第三代大鼠并沒有接觸尼古丁。
The cause of the grand-offsprings' asthma, Dr Rehan believes, is epigenetic modification.
Rehan博士認為，第三代大鼠的哮喘是表觀遺傳中的改性現(xiàn)象。
Nicotine is not only affecting lung cells, but also affecting sex cells in ways that cause the lungs which ultimately develop from those cells to express their genes in the same abnormal ways.
尼古丁不僅侵襲肺部細胞，還會影響生殖細胞，使得生殖細胞在發(fā)育器官時，在肺部異常表達基因，導(dǎo)致新發(fā)育的肺部同樣受到尼古丁的不良影響。
Exactly what those epigenetic changes are is hard to track down.
表觀遺傳現(xiàn)象具體引起了哪種變化，目前難以獲知。
The team have started looking, but could find no clear pattern except that one form of nicotine-induced acetylation, that of H3 histones, could be blocked by a molecule called RGZ.
研究團隊已經(jīng)開始研究這一問題，但目前只研究出一種明確的模式：尼古丁會引起H3組蛋白的乙酰化，
This molecule is also known to protect lungs against the asthma-causing effects of nicotine.
進而導(dǎo)致一種叫做RGZ的分子受到抑制，而目前已知RGZ分子可以保護肺臟，使其免受由尼古丁引起的哮喘。
That suggests it is the acetylation of H3 histones rather than the methylation of DNA itself that is creating the effect.
這表明由尼古丁引起的哮喘是源于H3組蛋白的乙酰化，而非DNA自身的甲基化作用。
Which crucial genes these histones surround remains obscure.
研究團隊目前沒有研究出這些受影響的組蛋白包含著哪些關(guān)鍵基因，
Nor have the team yet found out whether the epigenetic effect they have discovered reaches further than grand-offspring.
也沒有發(fā)現(xiàn)表觀遺傳的影響是否會延續(xù)至第三代以下的后代。
If it does, though, it suggests that epigenetics really might act like the biblical curse:
然而，如果有研究表明后生效應(yīng)會世代相傳的話，這就表明表觀遺傳現(xiàn)象真真是有如圣經(jīng)上的詛咒：
that the sins of the fathers will be visited on the sons, even unto the third and fourth generations.
父輩的罪孽，會降罪至他們的下一代身上，甚至?xí)永m(xù)至第三代或者第四代。
