英语听力文摘 English Digest 508、昆虫也有舌头吗？

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　　Don: I love that game！

 

　　Y: I don't know about that. But the little plastic tongue-like part of that strange insect like body did inspire me to wonder about taste and insects. Do insects have tongues? And if so, what do they taste?

 

　　D: Well,scientists have mapped out the Drosophila fruit fly equivalent of our tongue and have made some interesting discoveries. Taste receptors are actually located in a variety of places on the fly's body, but its primary taste organ is called the labellum. It’s positioned on the creature’s head, and it looks like a hairy pair of lips.

 

　　The labellum does certainly look different from our tongue, and the genes¹ involved in fruit fly taste are distinct from our own taste genes, but despite all that, taste in insects and mammals works similarly.

 

　　Taste receptors send signals to the brain, and the fly responds accordingly–it chows down if the brain determines the food is safe, and it looks elsewhere if the food item is determined² suspect. In particular, fruit flies respond to sweet and bitter tastes.

 

　　They have such a wide variety of combinations of bitter-sensitive tasting cells that scientists believe that when it comes to bitter flavors, fruit flies have more discriminating³ tastes than us mammals. This knack⁴ for tasting bitter flavors may help them distinguish between harmful and safe bacteria on a spoiled piece of fruit.

 

　　Y: And I supposed that understanding taste in insects may lead to better repellants to keep them off our fruit in the first place.

 

　　D: You got it!

 

　　Y：有人给我女儿买了款叫“Cudies”的游戏。

 

　　Don：我喜欢那个游戏！

 

　　Y: 我不太了解。但是那只奇怪的塑料昆虫有个部位跟人一样—— 很小，像舌头一样，这让我对昆虫和（它的）味觉产生了好奇。昆虫也有舌头吗？如果有，它们又是怎样品味的呢？

 

　　D: 这样的，科学家已经提出果蝇属的果蝇有着跟我们舌头一样的（部位），还发现了一些有趣的东西。（果蝇的）味觉感受器实际上是位于果蝇身体的很多部位，但是它们最主要的味觉器官叫“唇瓣”。唇瓣位于果蝇的头部，看起来像一对长毛的嘴唇一样。

 

　　唇瓣肯定看起来跟我们的舌头不一样。果蝇的味觉基因跟我们的味觉基因也是有区别的。但是尽管如此，昆虫和哺乳动物的味觉系统运作起来是相似的。

 

　　味觉感受器想大脑传送新号，果蝇就会做出相应的反应。如果大脑鉴定食物是安全的话，果蝇就会吃下它；如果食物（的安全性）有待考证，它们就会另觅（食物）。对于果蝇来说，它们尤其会对甜的和苦的（食物）有反应。

 

　　它们有着大量的对苦味很敏感的味觉细胞组合，这让科学家相信在遇到苦味的时候，果蝇会比我们哺乳动物更能够识别。（果蝇）品尝苦味的本领或许可以帮助它们在腐烂的水果上区分有害和安全的细菌。

 

　　Y: 我觉得理解昆虫的味觉可能会帮助我们从一开始就让它们原理我们的水果。

 

　　D: 你已经会了！

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