英语听力文摘 English Digest 393、单亲蜜蜂王国

Fatherless Honeybees

How male honeybees can be without fathers? The reason lies in what’s called a haploidiploid system of sex determination. Approximately one-fifth of the animal kingdom, including ants and wasps, use this system. What it boils down to is that males are the result of unfertilized eggs whereas females are born from fertilized eggs.

But in bees there is an added complication since there is a gene¹ that determines whether a bee will be male or female. It’s all in the numbers. Here’s how it works. 

A scientist isolated a gene called CSD, or Complimentary² Sex Determiner. There are 19 different versions of this particular gene. It doesn’t matter which one of these 19 versions a male inherits from his mother; he’s going to be male because of the fact that he has only one of these CSD genes³.

Accordingly, a female becomes a female because she has two CSD genes, except for one catch. And that catch is a bee in the bonnet⁴ of bee breeders.

Honeybee breeders often inbreed their bees in order to ensure desired traits. However, when bees are inbred it’s possible for fertilized eggs to end up with two copies of the same version of the CSD gene. The result is that the fertilized eggs would normally develop into workers or a new queen, develop into sterilized males.

Worker bees sense these sterile⁵ males when they’re still larvae⁶, and they kill them. Before you know it, your honeybee colony has died out. The good news is that now that scientists understand more about how sex is determined⁷ among honeybees, they may discover solutions to this problem.

没有父亲的蜜蜂

雄蜂是如何在没有父亲的情况下生存的呢？其原因在于一种叫做haploidiploid的性别鉴定系统。包括蚂蚁王国及黄蜂帝国在内的约五分之一的动物王国都是采用这一性别鉴定系统。归根究底就是：雄性是由未受精卵繁育而来，而雌性则是由受精卵繁育而来的。

但是，这一系统在蜜蜂王国内使用会比较复杂。因为蜜蜂体内还有一个基因决定着蜜蜂的雌雄。这一切的关键在与数量。下面我们就来谈谈它是如何起作用的。

科学家们从蜜蜂体内分离出一种基因，叫做性别决定基因（简称CSD）。一般说来，这种基因在蜜蜂体内会有19个版本。哪一个性别决定基因是遗传自女蜂王的并无所谓。关键的是，如果说蜜蜂体内只有一个性别决定基因的话，毫无疑问，它必定是只雄蜂。

那么，有两个性别决定基因的就是雌性蜜蜂，但有一种蜜蜂是例外。那就是担任着繁殖下一代重任的女蜂王了。

蜜蜂一般都是近亲繁殖，以此确保下一代能具有一定的特性。然而，在进行近亲繁殖时，受精卵可能会拥有两个相同的性别决定基因的版本。自然而然的，这些受精卵会发育成为工蜂或是新一代的女蜂王，或是不育的雄蜂。

当这些不育的雄蜂还处在幼虫期时，若是被工蜂所发现，那小命也就没了。在人们知道之前，这一蜂群已然消亡。在这里，科学家们还是带来了一个好消息：科学家们对蜜蜂的性别决定机制已有了一定的了解，他们很快就会找出解决这个问题的方法。期待ing……

Note:   a bee in the bonnet  of    对……有独特的见解/想法…

 

1 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

2 complimentary   

adj.赠送的，免费的，赞美的，恭维的

参考例句：

• She made some highly complimentary remarks about their school.她对他们的学校给予高度的评价。
• The supermarket operates a complimentary shuttle service.这家超市提供免费购物班车。

3 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

4 bonnet   

n.无边女帽；童帽

参考例句：

• The baby's bonnet keeps the sun out of her eyes.婴孩的帽子遮住阳光，使之不刺眼。
• She wore a faded black bonnet garnished with faded artificial flowers.她戴着一顶褪了色的黑色无边帽，帽上缀着褪了色的假花。

5 sterile   

adj.不毛的，不孕的，无菌的，枯燥的，贫瘠的

参考例句：

• This top fits over the bottle and keeps the teat sterile.这个盖子严实地盖在奶瓶上，保持奶嘴无菌。
• The farmers turned the sterile land into high fields.农民们把不毛之地变成了高产田。

6 larvae   

n.幼虫

参考例句：

• Larvae are parasitic on sheep.幼虫寄生在绵羊的身上。
• The larvae prey upon small aphids.这种幼虫以小蚜虫为食。

7 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。