摘要：
　　肥胖的毛毛虫钻进茧中，如何就变成了美丽的蝴蝶，这一直都是自然界的一个秘密。美国科学家最近的一项研究揭示了这个神奇过程的一部分，他们发现在变成蝴蝶的过程中，毛毛虫要在茧中燃烧大量的脂肪，以便为化蝶提供足够的能量。
　　What goes on in a cocoon as a caterpillar changes into a butterfly remains one of nature's best kept secrets. But a new study reveals one part of the process: The insects burn a tremendous amount of fat while hibernating during the transformation.

　　美国俄勒冈健康科学大学的科学家们在最新一期《脂肪研究杂志》上发表研究报告指出，一条蠕动的毛毛虫要变成美丽的蝴蝶，需要经过激烈的化学变化。变化过程需要耗费大量的能量，那么这种能量的一个合理来源就是积聚在毛毛虫身体中的脂肪。

　　该大学的科学家威廉·康纳说，尽管（蝴蝶）幼虫看起来似乎是在睡觉，有人可能以为休眠只需要很少的能量，但是如果倒过来看，就能明白茧中发生了非常巨大的代谢活动。

　　科学家对南美大闪蝶幼虫的食物消耗进行了分析，还研究了幼虫及其进食的脂肪构成，另外还研究了刚刚爬出茧子的蝴蝶。研究结果发现，尽管蝴蝶和幼虫的饮食与身体组织中都含有大量的多不饱和脂肪酸，但幼虫却要比蝴蝶胖3倍。大量的脂肪同时形成一堵厚厚的"墙"，阻挡一些对幼虫和蝴蝶非常重要的物质外泄，尤其是在化蝶过程中。

　　It takes drastic chemical changes to morph a squirmy caterpillar into a beautiful butterfly, and scientists have estimated that this process requires loads of energy to go forward. A logical source of that energy is stored body fat.

　　"It appears as though the larva is sleeping, and one might think that very little energy would be required in hibernation," said William Connor of the Oregon Health and Science University. "But the reverse must be true since a great deal of metabolic activity is occurring in the butterfly chrysalis."

　　On a daily basis, researchers analyzed the food consumption of Morpho peleides (popularly called blue morpho) butterfly larvae in Belize. They also analyzed the fat composition and content of both the food and the larvae, as well as of the butterfly once it emerged from its cocoon. While both the butterfly and larva diets and tissues had high concentrations of polyunsaturated fatty acids, the larva had nearly three times more fat than the butterfly. The fats can act as building blocks for other substances that may be very important in the health of the both the larva and the butterfly, Connor said, particularly during metamorphosis.

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