转自丁香园动态版 译者：Docofsoul
Dietary restriction extends healthy lifespan in diverse organisms and reduces fecundity 1, 2.
对多种生物体的观察与研究表明：节食有利健康长寿，但制约了生物体的生育能力。
It is widely assumed to induce adaptive reallocation of nutrients from reproduction to somatic maintenance, aiding survival of food shortages in nature3, 4, 5, 6.
通常认为，在自然界食物缺乏的情形下，生物体内发生营养适应性重新分配，使得维持生物体生育力的营养向维持其躯体健康方向转移从而有利生存。
If this were the case, long life under dietary restriction and high fecundity under full feeding would be mutually exclusive, through competition for the same limiting nutrients.
如果情形是这样的话，对同一有限的营养物的竞争行为就会导致鱼与熊掌不可得兼的情形： 要么节食而长寿，要么三餐饱食生育力旺盛但寿命缩短。
Here we report a test of this idea in which we identified the nutrients producing the responses of lifespan and fecundity to dietary restriction in Drosophila.
依据这一设想，我们用果蝇作了一次试验，证实了对寿命产生影响、而节食情形下则对生育力产生影响的营养物。
Adding essential amino acids to the dietary restriction condition increased fecundity and decreased lifespan, similar to the effects of full feeding, with other nutrients having little or no effect.
在节食情形下，给生物体添加必需的氨基酸可增强其生育力，但缩短了其寿命。此与三餐饱食产生的相关效应类似，而其它营养物则基本无法产生此种效应。
However, methionine alone was necessary and sufficient to increase fecundity as much as did full feeding, but without reducing lifespan. Reallocation of nutrients therefore does not explain the responses to dietary restriction.
不过，单独添加蛋氨酸对提高生育力是必要的、也是充分的，与饱食有异曲同工之妙， 但是不会缩短生物体的寿命。因此，营养的重新分配并不能解释节食情形下的响应状况。
Lifespan was decreased by the addition of amino acids, with an interaction between methionine and other essential amino acids having a key role. Hence, an imbalance in dietary amino acids away from the ratio optimal for reproduction shortens lifespan during full feeding and limits fecundity during dietary restriction.
添加氨基酸会缩短生物体寿命，此中蛋氨酸与其它基本氨基酸之间的交互作用扮演了关键性角色。因此，饮食中氨基酸失衡而偏离有利生育的最佳比例时，虽然饱食，生物体的寿命也会缩短，而节食情形下则限制了生育力。
Reduced activity of the insulin/insulin-like growth factor
signalling pathway extends lifespan in diverse organisms7, and we find that it also protects against the shortening of lifespan with full feeding.
减少胰岛素/胰岛素样生长因子信号通道的活动性可使多种生物体的寿命延长，并且，我们也发现，在饱食情形下，这样做也能防止寿命缩短。
In other organisms, including mammals, it may be possible to obtain the benefits to lifespan of dietary restriction without incurring a reduction in fecundity, through a suitable balance of nutrients in the diet.
在其它包括哺乳动物的生物体中，通过调整饮食以达到适当的营养平衡，从而使得节食既能长寿、又能保持生育力是可能的。
（Docofsoul 译于 2009-12-5）
注：此摘要标题为译者所加。
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