英语听力文摘 English Digest 366、神奇的“鼻子”（在线收听）

SpermSniff Out Their Targets
精子靠“嗅觉”发现卵子

Scientists who study human sperm have long wondered whether human sperm could somehow sense the presence of an egg. Then, just about a decade ago, it was discovered that sperm have proteins on them that react to the presence of certain chemicals. In fact, these are the same molecules used by nerve cells in your nose when you sniff out a scent.

Nothing that looks like a nose of course, but these chemical-sensing proteins act like noses. Researchers call these sensory devices “olfactory receptors.” More recent studies have started figuring out what kind of chemical attracts a sperm.

The most effective spermattractor is called “bourgeonal.” Bourgeonal is a floral scent. When sperm sense the presence of bourgeonal, they race toward it. Their speed goes from eighteen point three micrometers per second up to a whopping thirty point one. The most likely thing is that bourgeonal just happens to be structurally similar to another chemical produced by a female egg.

研究人类精子的科学家们长期以来都很疑惑：精子是否能以某种方式察觉到卵子的存在。大约就在十多年前，人们发现精子本身含有一些蛋白质对某些特定的化学物质会产生反应。实际上，那些就是我们鼻子闻气味时需要的神经细胞。

当然不是真正的鼻子，但可以嗅到化学五的蛋白质就像鼻子一样。研究人员把这些感知工具叫做“嗅觉感受器”。很多近代的研究已经开始弄清楚吸引精子的是那种化学物质。

最有效的精子吸引子叫bourgeonal。Bourgeonal一种花香化合物。当精子嗅到这种味道，就会迅速向它移动。精子的速度从每秒18.3微米上升到30.1微米。最有可能的是， bourgeonal与由卵子产生的一种化学物在结构上是相似的。