SSS 2011-09-26
时间:2011-10-07 06:24:27
搜索关注在线英语听力室公众号:tingroom,领取免费英语资料大礼包。
(单词翻译)
This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.
Life requires balance. We balance work and family. We eat a balanced breakfast, sometimes. And we balance our electrolytes. That salt-water synergy is not just key to our health, but to our very existence. Because the appearance of
molecules1 that maintain our fluid balance coincide with the evolution of multicellular life. The findings appear in the journal
Physiological2 Genomics.
When it comes to osmolarity, single cells keep it simple. They adjust their fluid
intake3 by importing or exporting salts across their
membranes4. But once a creature is multicellular, things are more complex. Many cells don't have direct access to the environment, so a complex system of
hormones5 and
sodium6 channels and pumps has to manage the movement of salts, cell by cell, to keep the whole body hydrated.
To trace the evolution of this regulatory system, scientists searched the genomes of organisms that represent the major branches of life's tree. And they found that two proteins—a sodium channel and part of a sodium pump—arose slightly before the first multicellular animals. Which strongly implies that the ability to regulate electrolytes is a big reason we're here. As any scientists worth their salt will tell you.
Thanks for the minute. For Scientific American's 60-Second Science, I'm Karen Hopkin.
分享到: