【科学60秒】和藻类共生的蝾螈_英语听力练习mp3下载-科学-沪江听力酷

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【科学60秒】和藻类共生的蝾螈

听力简介：

A rolling stone gathers no____1____. But a salamander embryo can attract algae. Inside its tissues and cells. This intimate________—the first ever seen between algae and a vertebrate—is revealed in the Proceedings of the National Academy of Sciences.

Spotted salamanders lay their eggs in pools in spring. And the egg ________ 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 ____4____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____5____.
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