【英语时差8，16】大小形状不一的番茄

 Ya?l: Hey Don, what's that?

Don: It's a tomato I found! Don't you think it looks like Richard Nixon? I wonder why tomatoes and other fruits sometimes grow into such different shapes.

Y: Scientists wonder about that too, and they are a step closer to solving the mystery now.

D: Really? Why?

Y: As you already noticed, some fruits can grow in a wide variety of shapes and sizes. Wild tomatoes, for instance, are very small and round, but through selective breeding we now have cultivated tomatoes that may be pear-shaped, egg-shaped, or even donut-shaped.

Little was known about the mechanisms¹ behind shape diversity, however, until scientists studied a gene² called SUN. They chose to study the SUN gene because they noticed it was common in tomato varieties with elongated³ shapes.

The team isolated⁴ the specific part of tomato DNA⁵ that contained the SUN gene from normal and elongated tomatoes.

To test if the SUN gene were responsible for the elongated shape, the team inserted active copies of the SUN gene into the DNA of wild tomato plants.

D: The plants with small, round fruits?

Y: Exactly. When the SUN gene was inserted and "turned on" in wild tomatoes, the plants produced very elongated fruits instead of round ones! Then the scientists inactivated⁶ the SUN gene in the transformed wild tomato plants. With the gene switched off, the plants produced round small fruits again.

D: Is the SUN gene found in other plants? Because... I also found this pepper that looks like you, Ya?l!

Y: Thanks, Don.

D: Since tomatoes and peppers are closely related, it will be interesting to see if and how the SUN gene functions in peppers and other fruits.  

1 mechanisms   

n.机械( mechanism的名词复数 )；机械装置；[生物学] 机制；机械作用

参考例句：

• The research will provide direct insight into molecular mechanisms. 这项研究将使人能够直接地了解分子的机理。 来自《简明英汉词典》
• He explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》

2 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。

3 elongated   

v.延长，加长( elongate的过去式和过去分词 )

参考例句：

• Modigliani's women have strangely elongated faces. 莫迪里阿尼画中的妇女都长着奇长无比的脸。
• A piece of rubber can be elongated by streching. 一块橡皮可以拉长。 来自《用法词典》

4 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。

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 inactivated   

v.使不活泼，阻止活动( inactivate的过去式和过去分词 )

参考例句：

• Molluscicides are quickly inactivated by sunlight and adsorption to mud organic matter. 灭螺剂因阳光作用、泥土及有机物质的吸收会很快失效。 来自辞典例句
• Viruses were inactivated by BPL and the toxicity measured again. BPL对病毒进行灭活，测定残存毒力。 来自互联网