2007年VOA标准英语-Scientists Find DNA That Determines Dog Size

By David McAlary
Washington
05 April 2007

Scientists have discovered a genetic² reason why some dogs are small and others big. They say the finding has implications beyond canine³ size, since the work applies to the study of other complex genetic traits, such as diseases and behaviors caused by multiple genes⁴. VOA's David McAlary reports.

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American humorist Mark Twain once said that it is not the size of the dog in the fight that matters, it is the size of the fight in the dog. Nevertheless, a team of U.S. geneticists says size does matter and has found the key to its extreme diversity in dogs.

Think of the difference between a Chihuahua and a Great Dane.

No other mammal has as great a range of sizes as the dog does. The researchers now understand the genetic basis for that variation, and explain it in the journal Science.

What they found is a piece of dog DNA that regulates the activity of a nearby growth gene¹ called IGF-1. Study leader Elaine Ostrander of the U.S. government's National Human Genome Research Institute near Washington says the researchers saw it first in Portuguese⁶ water dogs. Small members of the breed had one version of the gene and the large ones had a different one.

"That was interesting, but not shocking. What really blew our socks off is when we started looking at other breeds, we found that all the small breeds had the exact same genetic signature at IGF-1 as did the small Portuguese water dogs, and large dogs breeds had the same signatures as what we found in the large Portuguese water dogs," he said.

Ostrander and her colleagues began researching dog size because it was the easiest genetically⁷ complex trait to measure. They have not determined⁸ the exact mutation⁹ in the regulatory DNA that influences the growth gene, but she says finding the DNA region is a model for how to track down the genetic causes of other complex, multi-gene traits.

"If we can figure out how to do this in morphology, we can probably figure out how to do it in behavior as well, and understanding the vocabulary of growth and development gives us entrée into understanding disease," he said.

Another member of Ostrander's group, University of Utah geneticist Gordon Lark¹⁰, says the scientists are now studying autoimmune diseases in dogs - diseases where the immune system attacks the animal rather than protects it, such as arthritis¹¹ or allergies¹². He says the work could eventually lead to discoveries about the genetic basis for complex human ailments¹³.

"Dogs have about 200 to 300 diseases in common with humans and they share the same environment. So for a very complex disease such as cancer, they are an ideal animal to study. And now that the dog genome has been sequenced, it can be compared directly to the human genome," he said.

Lark and Ostrander say they could not have carried out their study on dog size if it were not for the cooperation of hundreds of dog owners across the United States who sent in x-rays and DNA samples from their pets. Lark says it was not practical for them to house many different breeds.

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 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

3 canine   

adj.犬的，犬科的

参考例句：

• The fox is a canine animal.狐狸是犬科动物。
• Herbivorous animals have very small canine teeth,or none.食草动物的犬牙很小或者没有。

4 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

5 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

6 Portuguese   

n.葡萄牙人；葡萄牙语

参考例句：

• They styled their house in the Portuguese manner.他们仿照葡萄牙的风格设计自己的房子。
• Her family is Portuguese in origin.她的家族是葡萄牙血统。

7 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

8 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。

9 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

10 lark   

n.云雀，百灵鸟；n.嬉戏，玩笑；vi.嬉戏

参考例句：

• He thinks it cruel to confine a lark in a cage.他认为把云雀关在笼子里太残忍了。
• She lived in the village with her grandparents as cheerful as a lark.她同祖父母一起住在乡间非常快活。

11 arthritis   

n.关节炎

参考例句：

• Rheumatoid arthritis has also been linked with the virus.风湿性关节炎也与这种病毒有关。
• He spent three months in the hospital with acute rheumatic arthritis.他患急性风湿性关节炎，在医院住了三个月。

12 allergies   

n.[医]过敏症；[口]厌恶，反感；（对食物、花粉、虫咬等的）过敏症( allergy的名词复数 )；变态反应，变应性

参考例句：

• Food allergies can result in an enormous variety of different symptoms. 食物过敏会引发很多不同的症状。 来自辞典例句
• Let us, however, examine one of the most common allergies; hayfever. 现在让我们来看看最常见的变态反应的一种--枯草热。 来自辞典例句

13 ailments   

疾病（尤指慢性病），不适( ailment的名词复数 )

参考例句：

• His ailments include a mild heart attack and arthritis. 他患有轻度心脏病和关节炎。
• He hospitalizes patients for minor ailments. 他把只有小病的患者也送进医院。