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  3. Mothers interfere with their children’s lives even more than most offspring realize. That they nag about eating habits is well k

Mothers interfere with their children’s lives even more than most offspring realize. That they nag about eating habits is well k

admin2022-08-06  1
问题     Mothers interfere with their children’s lives even more than most offspring realize. That they nag about eating habits is well known. What goes unnoticed is that mothers leave cells inside their children’s bodies, which may help with repairs when a child’s own cells go disorderly.
    This form of maternal interference is called microchimerism—the presence of a small number of cells that originate from another individual and therefore genetically distinct from the cells of the host individual. A mother’s cells can endure until a child reaches adulthood and perhaps throughout life. But scientists do not know exactly how common microchimerism is. It is detected more often in people with autoimmune conditions, which has led to the suggestion that the maternal cells could trigger those diseases. But healthy people have them too, seemingly with no ill effects.
    Lee Nelson, of the University of Washington, suspects that everybody has a few maternal cells. Her most recent work argues that, at least in some cases, they help rather than harm. Dr Nelson and her colleagues took blood samples from three groups of young volunteers and their mothers. The first group comprised 94 young volunteers who had type 1 diabetes; the second were 54 of their healthy siblings (brothers or sisters); and a further 24 were children without diabetes who were not related to anyone else in the study. The researchers then compared DNA from the mothers and their children.
    Because mothers pass copies of about half their genes to their children, some genes in any child-mother pairs will be unique to the mother—those that the child has not inherited from her. Others— versions of genes that came from dad—will be unique to the child. Dr Nelson used the uniquely maternal genes to find mothers’ cells in the volunteers’ blood. The technique found maternal cells in about half the diabetics’ samples, but in only about one-third of the healthy siblings’ samples and in less than one-fifth of those from the unrelated volunteers. Moreover, the microchimerism was not only more common but also more pronounced in diabetics.
    Dr Nelson also looked for signs that the maternal cells had caused the diabetes but found no evidence. So, contrary to established opinion, she believes maternal cells can do children good. These cells may help any bodily organ work better, she says, apart from the reproductive kind. Mothers’ protective interference goes on—seen and unseen.
Some genes in child-mother pairs will be unique to the mother in that
选项 A、these genes haven’t been passed to the child.
B、less than half of the genes have been passed to the child.
C、these genes come from the father.
D、the child is not willing to inherit these genes.
答案A
解析 根据第四段第一句话可知母亲独有的基因指那些没有被孩子继承的基因，因此A项正确。文中没有具体提到基因数量和独有性的关系，因此B项错误；C项解释的是孩子独有基因的来源；D项不符合客观事实。
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