VOA慢速英语 2008 0520b

SCIENCE IN THE NEWS - Progress Against Witchweed, a Killer¹ of Sorghum² Crops in Africa
Researchers may someday copy proteins found in alligator³ blood to produce infection-fighting drugs for people. Transcript⁴ of radio broadcast:
19 May 2008

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Faith Lapidus.

VOICE TWO:
　

Proteins from the blood of American alligators5 could provide a new source of antibiotics7 for fighting human infections

And I'm Steve Ember. This week, we will tell about an American effort against a killer of sorghum crops in Africa. We will tell how blood from alligators may someday prove helpful to people. We will also tell how American doctors removed a diseased appendix through a man's mouth.

(MUSIC)

VOICE ONE:

Research scientists may have found one answer to a food production problem that causes crop failure in Africa. The researchers say they have produced a seed that can protect sorghum crops from a weed called striga.

Kassim Al-Katib is a weed expert at Kansas State University in the United States. Mitch Tuinstra is a genetics and plant-breeding expert. He works at Purdue University in Indiana, but formerly⁸ worked at Kansas State.

Their target weed has a pleasant looking purple flower. But striga’s action is far from pleasant. Striga causes six or seven billion dollars in crop damage every year to African grain sorghum.

VOICE TWO:

In Africa, striga is called witchweed. The plant threatens grains in the eastern and western parts of the continent. Sorghum is important to the local food supply. It can be used in bread and other foods.

Witchweed is among the few flowering weeds that act as parasites¹⁰ on other plants. Witchweed steals water and needed nutrients¹¹ from sorghum roots. And it also attacks the sorghum with a poisonous substance.

Witchweed has another unusual quality. It requires chemical signals from sorghum seeds to grow. But if no sorghum seeds are present, witchweed seeds can lie under the soil for years. The seeds begin to grow only when they receive the needed chemical signals.

VOICE ONE:

Witchweed seed capsules, or covers, can hold four hundred to five hundred seeds. Winds and rain spread the parasite⁹. Researcher Mitch Tuinstra warms that if you see witchweed on your farm, you are in trouble. The plant can reduce a farmer’s crop. Or it can completely destroy many hectares of grain. Also, witchweed is very difficult to move after it invades an area.

Damage from the parasite is worst in dry soil with low fertility. It often strikes farmers who work the poorest land. This can mean disaster for people who already lack enough to eat. Some African farmers have attempted crop rotation¹². But planting one kind of crop for a season and another crop the next did not prove very effective.

VOICE TWO:

To deal with witchweed, the American researchers developed special sorghum-seed genes¹³. These genes can accept carefully chosen chemical herbicides without being harmed. Herbicide treatments kill unwanted insects or plant life. The researchers placed the herbicides on the sorghum seeds. Mister al-Katib said the seed kills the witchweed as the sorghum grows.

Mister Tuinstra directed greenhouse tests of the seeds in the Netherlands in two thousand five and two thousand six. Similar studies took place in field trials in Mali and Niger. These studies showed the treatment to be highly successful.

Mister Tuinstra recently returned from Africa, where he met with agriculture experts. They are working to develop local kinds of sorghum that employ the protective genes. The project is a collective research program under the United States Agency for Aid and Development.

(MUSIC)

VOICE ONE:

You are listening to the VOA Special English program SCIENCE IN THE NEWS. With Steve Ember, I'm Faith Lapidus in Washington.

People who have observed alligators know the big reptiles¹⁴ can sometimes get hurt. They suffer wounds as they fight with other alligators. They can also get hurt in traps. But alligators often recover without developing deadly infections.

Now scientists in the United States say they have shown that blood from alligators helps to protect the animals from infection. They are also suggesting that parts of proteins from the alligators' blood may someday treat infections in human beings.

VOICE TWO:

The scientific team carried out experiments with the parts of proteins known as peptides from white blood cells. The team says the peptides killed twenty-three kinds of bacteria, including some that resist treatment with antibiotic⁶ drugs.

It also says the proteins from the alligators destroyed most of HIV, the virus that causes AIDS. The sometimes-deadly infection called MRSA also was affected¹⁵. MRSA has threatened patients in hospitals worldwide. The proteins also affected the yeast¹⁶ infection, Candida albicans.

Mark Merchant is a biochemist at McNeese State University in Lake Charles, Louisiana. He and other team members collected blood from American alligators. They identified white cells that fight disease. Then they removed the peptides, or active proteins, from the cells.

VOICE ONE:

Lancia Darville of Louisiana State University is another member of the research team. She says the team is now sequencing the peptides from the alligator blood. When this separation and identification process is completed, their chemical structure will be known. This raises the possibility of copying the blood proteins to create drugs for human beings.

Animals other than alligators have the peptides in their skins. They include crocodiles, which are similar to alligators. Komodo dragons, frogs and toads¹⁷ also have them.

Miz Darville presented the team’s research at a meeting last month of the American Chemical Society in New Orleans, Louisiana.

(MUSIC)

VOICE TWO:

Medical researchers keep looking for less invasive ways to perform operations. The aim is to cut less and to reduce pain and recovery time. Some researchers see a future in NOTES. NOTES is short for a treatment called Natural Orifice Translumenal Endoscopic Surgery.

In simple terms, what this means is the removal of diseased organs through the body's natural openings. For example, a man in California recently had his appendix removed through his mouth.

VOICE ONE:

Twenty-five years ago, having your appendix removed meant staying in the hospital for as long as a week. Patients returned home with an ugly and permanent mark on their abdomen¹⁸.

Since the late nineteen eighties, laparoscopic surgery has gained popularity. It leaves only small marks where holes were made in the skin. The doctor works with a system called a laparoscope, usually connected to a video camera. Laparoscopic surgery rarely requires a hospital stay.

VOICE TWO:

With the newest kind of surgery, doctors make a small cut in the patient's belly¹⁹ button. A camera is placed through the hole to help guide the surgical²⁰ instrument.

Doctors performed the operation two months ago at the University of California San Diego Medical Center. It was done as part of a study to test new methods of minimally²¹ invasive surgery. The operation lasted three hours. Santiago Horgan led the team of doctors. He is the director of U.C. San Diego's Center for the Future of Surgery.

VOICE ONE:

The doctors used a long robotic tube to pass the instrument down the patient's throat. Then they made a cut in the wall of the stomach. The cut was made to pass the instrument through to the appendix for removal.

The researchers said they believed it was the country's first removal of a diseased appendix through the mouth. They said India was the only other country to report such an operation.

VOICE TWO:

The patient in California, Jeff Scholz, is reported to have said he recovered quickly and with little pain. He also said he was lucky to be chosen for the experimental surgery.

But some doctors say they are not sure this kind of operation is worth the possible risks. They say stomach fluids could leak if the hole in the stomach wall is not closed completely. A mistake, they say, could be life-threatening.

The surgical method is still being studied to see if it is better than traditional surgeries.

(MUSIC)

VOICE ONE:

This SCIENCE IN THE NEWS program was written by Jerilyn Watson and Brianna Blake. Mario Ritter was our director. I'm Faith Lapidus.

VOICE TWO:

And I'm Steve Ember. We would like to hear from you. Write to us at Special English, Voice of America, Washington, D.C., two-zero-two-thirty-seven, U.S.A. Or send electronic messages to [email protected]. Join us again at this time next week for more news about science in Special English on the Voice of America.

1 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

2 sorghum   

n.高粱属的植物，高粱糖浆，甜得发腻的东西

参考例句：

• We can grow sorghum or maize on this plot.这块地可以种高粱或玉米。
• They made sorghum into pig feed.他们把高粱做成了猪饲料。

3 alligator   

n.短吻鳄(一种鳄鱼)

参考例句：

• She wandered off to play with her toy alligator.她开始玩鳄鱼玩具。
• Alligator skin is five times more costlier than leather.鳄鱼皮比通常的皮革要贵5倍。

4 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

5 alligators   

n.短吻鳄( alligator的名词复数 )

参考例句：

• Two alligators rest their snouts on the water's surface. 两只鳄鱼的大嘴栖息在水面上。 来自辞典例句
• In the movement of logs by water the lumber industry was greatly helped by alligators. 木材工业过去在水上运输木料时所十分倚重的就是鳄鱼。 来自辞典例句

6 antibiotic   

adj.抗菌的；n.抗生素

参考例句：

• The doctor said that I should take some antibiotic.医生说我应该服些用抗生素。
• Antibiotic can be used against infection.抗菌素可以用来防止感染。

7 antibiotics   

n.（用作复数）抗生素；（用作单数）抗生物质的研究；抗生素，抗菌素( antibiotic的名词复数 )

参考例句：

• the discovery of antibiotics in the 20th century 20世纪抗生素的发现
• The doctor gave me a prescription for antibiotics. 医生给我开了抗生素。

8 formerly   

adv.从前，以前

参考例句：

• We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
• This boat was formerly used on the rivers of China.这船从前航行在中国内河里。

9 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

10 parasites   

寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫

参考例句：

• These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
• Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。

11 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

12 rotation   

n.旋转；循环，轮流

参考例句：

• Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
• The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。

13 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

14 reptiles   

n.爬行动物，爬虫( reptile的名词复数 )

参考例句：

• Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
• Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》

15 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

16 yeast   

n.酵母；酵母片；泡沫；v.发酵；起泡沫

参考例句：

• Yeast can be used in making beer and bread.酵母可用于酿啤酒和发面包。
• The yeast began to work.酵母开始发酵。

17 toads   

n.蟾蜍，癞蛤蟆( toad的名词复数 )

参考例句：

• All toads blink when they swallow. 所有的癞蛤蟆吞食东西时都会眨眼皮。 来自《简明英汉词典》
• Toads have shorter legs and are generally more clumsy than frogs. 蟾蜍比青蛙脚短，一般说来没有青蛙灵活。 来自辞典例句

18 abdomen   

n.腹，下腹(胸部到腿部的部分)

参考例句：

• How to know to there is ascarid inside abdomen?怎样知道肚子里面有蛔虫？
• He was anxious about an off-and-on pain the abdomen.他因时隐时现的腹痛而焦虑。

19 belly   

n.肚子，腹部；(像肚子一样)鼓起的部分，膛

参考例句：

• The boss has a large belly.老板大腹便便。
• His eyes are bigger than his belly.他眼馋肚饱。

20 surgical   

adj.外科的，外科医生的，手术上的

参考例句：

• He performs the surgical operations at the Red Cross Hospital.他在红十字会医院做外科手术。
• All surgical instruments must be sterilised before use.所有的外科手术器械在使用之前，必须消毒。

21 minimally   

最低限度地，最低程度地

参考例句：

• Food spoilage problems occur with minimally processed, concentrated frozen citrus products. 食品的变质也发生在轻微加工的、浓缩冷冻的柑橘制品中。
• So, minimally, they are responsible for such actions and omissions. 所以，至少来说，他们要对这样的行为和忽略负责。