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托福听力练习-科学美国人60秒:蝾螈与藻类共生

2017-05-18 14:50:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频：蝾螈与藻类

　　科学美国人60秒听力练习：蝾螈与藻类共生

　　科学美国人60秒英文文本

　　A rolling stone gathers no moss. But a salamander embryo can attract algae. Inside its tissues and cells. This intimate co-habitation—the first ever seen between algae and a vertebrate—is revealed in the Proceedings of the National Academy of Sciences. [Ryan Kerney et al., "Intracellular invasion of green algae in a salamander host"]

　　Spotted salamanders lay their eggs in pools in spring. And the egg capsules actually look green, thanks to the algae that surrounds the resident embryos. That relationship benefits both parties. Algae feed on the nitrogen-rich waste products generated by the embryos. And the embryos bask in the oxygen given off by the algae. Take away their algae, and spotted salamander babies hatch smaller and less mature.

　　So that’s the eggs. But this study is the first to show that the algae actually inhabit the embryo itself. Using imaging techniques and DNA testing, scientists found algae inside the cells of young salamander embryos—and even in the reproductive tracts of some adult females.

　　Which suggests that some algae may be handed down directly from parent to child. More evidence that many individuals are really entire little ecosystems.

　　—Karen Hopkin

　　中文翻译请点击下一页

本文关键字: 托福听力 科学美国人60秒

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