英語聽力文摘508 昆蟲也有舌頭嗎？

Ya?l: Somebody bought my daughter a game called "Cuddies".

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 genes 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 determined 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 discriminating tastes than us mammals. This knack 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：有人給我女兒買了款叫“Cudies”的游戲。

Don：我喜歡那個(gè)游戲!

Y: 我不太了解。但是那只奇怪的塑料昆蟲有個(gè)部位跟人一樣—— 很小，像舌頭一樣，這讓我對(duì)昆蟲和(它的)味覺產(chǎn)生了好奇。昆蟲也有舌頭嗎?如果有，它們又是怎樣品味的呢?

D: 這樣的，科學(xué)家已經(jīng)提出果蠅屬的果蠅有著跟我們舌頭一樣的(部位)，還發(fā)現(xiàn)了一些有趣的東西。(果蠅的)味覺感受器實(shí)際上是位于果蠅身體的很多部位，但是它們最主要的味覺器官叫“唇瓣”。唇瓣位于果蠅的頭部，看起來像一對(duì)長(zhǎng)毛的嘴唇一樣。

唇瓣肯定看起來跟我們的舌頭不一樣。果蠅的味覺基因跟我們的味覺基因也是有區(qū)別的。但是盡管如此，昆蟲和哺乳動(dòng)物的味覺系統(tǒng)運(yùn)作起來是相似的。

味覺感受器想大腦傳送新號(hào)，果蠅就會(huì)做出相應(yīng)的反應(yīng)。如果大腦鑒定食物是安全的話，果蠅就會(huì)吃下它;如果食物(的安全性)有待考證，它們就會(huì)另覓(食物)。對(duì)于果蠅來說，它們尤其會(huì)對(duì)甜的和苦的(食物)有反應(yīng)。

它們有著大量的對(duì)苦味很敏感的味覺細(xì)胞組合，這讓科學(xué)家相信在遇到苦味的時(shí)候，果蠅會(huì)比我們哺乳動(dòng)物更能夠識(shí)別。(果蠅)品嘗苦味的本領(lǐng)或許可以幫助它們?cè)诟癄€的水果上區(qū)分有害和安全的細(xì)菌。

Y: 我覺得理解昆蟲的味覺可能會(huì)幫助我們從一開始就讓它們?cè)砦覀兊乃?/p>

D: 你已經(jīng)會(huì)了!