Well, technically the American chestnut tree is almost extinct.

从技术上讲，美国栗树几乎就灭绝了。

American chestnuts may, however, be about to rise again—thanks to genetic engineering.

多亏有了基因工程，美国栗树有望再次繁茂起来。

Engineering coral to withstand warming waters, restoring the American chestnut tree, the genetic rescue of the black-footed ferret.

改造珊瑚以抵御变暖的海水，重现美洲栗树，以及黑足雪貂的基因拯救计划。