在线英语听力室_免费在线英语听力学习网站

This is Scientific Americans' 60-Second Science.I'm Karen Hopkin .This will just take a minute.

When you hear things like, human DNA¹ differs from chimp² DNA by only a couple percent. You can’t help but wonder. How can that be? How can so few changes make such a big difference? Researchers working with fruit bats and mice think they have an answer. And it lies less in the animals’ genes⁴ than in the short snippets of DNA that control when and where and how vigorously genes are turned on. If you’ve ever thought that a bat is basically just a rodent⁵ with wings, you’re not too far from the mark. One of the most obvious differences between bats and mice is their forearms. Mice have these stubby legs, and bats have these large leathery wings. But even those differences are not as major as you might imagine. Mice and bats both have a gene³ called Prx one, which regulates limb development. But the gene is more active in the budding wings of bats. So the researchers took the piece of DNA that controls Prx one activity from a bat and stuck it into a mouse. The result pictured in the January 15 issue of Genes and Development- mice that have longer front legs. Ok, they didn’t spout⁶ wings, but the study shows that even small changes can have big consequences.

Thanks for the minute for Scientific Americans' 60-Second Science. I'm Karen Hopkin.