SSS 2010-01-29
时间：2018-12-02 作者：英语课 分类：Scientific American(一)月
Organisms evolved sexual reproduction so they could stay one step ahead of parasites 1. Or so the theory goes. But what about beasties that make babies without sex? How do they escape infection? A study in the journal Science suggests that for bdelloid rotifers, the answer is blowin’ in the wind.
Biologists believe that sex offers an evolutionary 2 advantage because it promotes genetic 4 diversity. Coming up with fresh new gene 3 combinations should allow organisms to outsmart parasites, which are also continuously evolving. But if that theory is correct then bdelloid rotifers, freshwater invertebrates 5 that haven’t had sex in at least 30 million years, should have been parasited into extinction 6 long ago. Yet here they are, alive and well.
To find out why, scientists infected rotifers with a deadly fungus 7. And they found that bdelloid rotifers can shake the infection by drying out, drifting away and then rehydrating once they land someplace moist but fungus-free. The fungi 8 don’t survive the desiccation, so the longer the bdelloids stay dry, the better off they be.
So for celibate 9 rotifers that want to stay clean, a good long dry spell is just what the doctor ordered.
—Karen Hopkin
- These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
- Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。
- Life has its own evolutionary process.生命有其自身的进化过程。
- These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
- A single gene may have many effects.单一基因可能具有很多种效应。
- The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。
- It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
- Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
- Insects and worms are all invertebrates. 昆虫和蠕虫都是无脊椎动物。 来自辞典例句
- In the earthworm and many other invertebrates, these excretory structures are called nephridia. 在蚯蚓和许多其它无脊椎动物中，这些排泄结构称为肾管。 来自辞典例句
- The plant is now in danger of extinction.这种植物现在有绝种的危险。
- The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。
- Mushrooms are a type of fungus.蘑菇是一种真菌。
- This fungus can just be detected by the unaided eye.这种真菌只用肉眼就能检查出。