儿童受虐阴影居然会遗传给后代，麻烦社会给幼儿一个阳光的环境

THE effects of child abuse can last a lifetime. Neglected or abused children have a higher risk of developing all sorts of ailments as adults, including mental illnesses such as depression but also physical ones like cancer and stroke. In fact, the effects may last even longer. Emerging evidence suggests that the consequences of mistreatment in childhood may persist down the generations, affecting a victim’s children or grand-children, even if they have experienced no abuse themselves.

儿童期受虐造成的影响可持续终生。遭到忽视或虐待的儿童在成人后罹患各类疾病的风险更高，即包括如抑郁等精神疾病，也包括如癌症与中风等身体疾患。事实上，受虐的影响有可能会持续更久。新出现的证据显示，童年期受虐的后果可能会代代延续下去，对受害者的子代甚至是孙代造成影响，即便后代本身并无受虐经历。

Exactly how this happens is not well understood. Rigorous experiments on human subjects are difficult. Scientists have therefore turned to rats and mice. But now Larry Feig of Tufts University and his colleagues have shown that psychological stress seems to cause similar changes in the sperm of both mice and men. Their study is published this week in Translational Psychiatry.

造成此情况的确切原因尚不明确。由于很难对人类实施严格控制条件的实验，因此科学家们转而去研究小鼠。但塔夫斯大学的Larry Feig与同事现已证明，心理压力似乎会令小鼠与男性的精子产生相似的变化。他们的研究于本周发表在《转化精神病学》。

Biologists know that traits are carried down the generations by genes. Genes encode proteins, and proteins make up organisms. That is still true. But it has recently become clear that it is not the whole story. Organisms regulate the activity of their genes throughout their lives, switching different genes on and off as circumstances require. It is possible that such “epigenetic” phenomena can be passed, along with the genes themselves, to an animal’s descendants. They offer a mechanism by which an animal’s life experiences can have effects on its offspring.

生物学家均知晓，生物特征是由基因进行代际传递的。基因编码蛋白质，而蛋白质构成生物。目前为止，事实仍是如此。但是最近人们愈发清晰地认识到，这并非事实的全部。贯穿生物的整个生命过程，它们都会调控基因的活动情况，随着环境的需求而开启或关闭不同类型的基因。因此，这种“表观”现象与基因一起遗传给动物的后代的情况是有可能发生的。上述理论提供了一种机制，通过这种机制，动物的生活经历便能够对其后代造成影响。

Hunting for signs of this, Dr Feig and his colleagues asked 28 male volunteers to complete a questionnaire assessing the severity of any trauma they had experienced as youngsters. They also asked their volunteers to provide sperm samples. They then looked for evidence for a common epigenetic mechanism involving small molecules called micro-RNAs. Their job is to bind to another molecule called messenger RNA, whose task in turn is to ferry information read from a gene to the cellular factories that create the required protein. Micro-RNA renders messenger RNA inactive, reducing the activity of the gene in question—and it can travel in sperm alongside DNA.

为了寻找该现象的迹象，Feig博士与其同事令28名男性志愿者完成一份调查问卷，旨在评估他们少年期所经历创伤的严重程度。研究人员还请志愿者们提供了精子样本。随后，他们开始寻找一种常见的表观遗传机制的证据，该机制涉及到一种名为微RNA的小分子。他们的任务是将其与另一种名为信使RNA的分子结合起来，后者的任务是把从基因中读取到的信息传递给制造所需蛋白质的细胞工厂。微RNA可降低所涉及到的基因的活动，从而令信使RNA失活-微RNA还可以与DNA一起通过精子进行传递。

Sure enough, upon screening the men’s sperm, the researchers found that concentrations of two types of micro-RNAs, miR-34 and miR-449, were as much as 100 times lower in samples from abused men.

毫无疑问，通过筛查被试男性的精子，研究人员发现，在受虐男性的精子样本中，两种微RNAs（即miR-34与miR-449）的浓度为正常精子的百分之一。

The team then turned to their mice. A standard way to stress mice is to move them to new cages, with new mice, from time to time until they reach adulthood. When the team did this they found that the stressed males had lower levels of miR-34 and miR-449 in their sperm. They mated these males with unstressed females. The resulting embryos also had low levels of the two micro-RNAs. And so in turn did sperm produced by the male offspring of these unions.

随后，该团体转而研究小鼠。向小鼠施压的一种基本方法，便是不断地把它们转移到新笼子中接触新伙伴，直到它们成年为止。进行此操作的团队发现，在承受压力的小鼠们的精子中，miR-34与miR-449浓度水平较低。他们令这些雄鼠与未受虐雌鼠交配。所生的幼仔同样在这两种微RNA上有着较低的浓度水平。这些(受压雄与未受压雌)结合所生的男性后代产生的精子亦是如此（miR-34与miR-449低)。

Dr Feig and others have shown that the female offspring of stressed male mice tend to be more anxious and less sociable. Furthermore, the sons of stressed fathers themselves produce stressed daughters. The effects of cage-shuffling, in other words, seem to last for at least three generations. The researchers have not demonstrated conclusively that miR-34 and miR-449 are responsible. But their results are suggestive.

Feig博士与其他人业已证明，受虐雄鼠的雌性后代倾向于更加焦虑且不善社交。此外，受虐雄鼠的儿子会生出焦虑的女儿。换句话说，也就是不断换笼所造成的影响，似乎至少可以延续三代。研究人员并未明确宣称miR-34与miR-449便是造成这一切原因。但他们的实验结果却暗示着事实或许就是如此。

To try to nail their case, the researchers plan to carry out a bigger study. This time, they will give questionnaires to their human subjects’ fathers, to tease out whether any epigenetic changes they observe arise from the childhood experiences of the subject or his father. Sisters and daughters may be included in the study, too. That is an ambitious goal. It is also a worthy one. Unless genetic engineering can one day be perfected, changes in genes are hard-wired. But epigenetic effects might be treatable, by boosting levels of particular micro-RNAs in sperm, for example. That could mean the legacy of abuse is no longer passed to future generations.

为了得出确切结论，研究人员计划开展一场更大规模的实验。这一次，他们将会给人类男性被试的父亲发调查问卷，从而搞清楚他们所观察到的表观遗传上的改变，究竟是出于被试本身还是他父亲的童年受虐经历。该研究可能还会把被试的姐妹与女儿包含进来。他们的目标虽然野心勃勃，但也相当有价值。除非有一天基因工程能够臻至完美，否则基因上的变化都是无可更改的。但是表观遗传的影响或许能够进行治疗，比如说，通过提高精子中特定微RNA的水平之类的。这或许也就意味着，虐待的后遗症将不会再传递给下一代。