名人轶事:People in America–Barbara McClintock

（单词翻译）

Written by - George Grow 

(THEME)

VOICE ONE:

I’m Doug Johnson.

VOICE TWO:

Barbara McClintock      

And I’m Barbara Klein with PEOPLE IN AMERICA in VOA Special English. Today,

we tell about Barbara McClintock. She was one of the most important

scientists of the twentieth century. She made important discoveries about

genes¹ and chromosomes³.

(THEME)

VOICE ONE:

Barbara McClintock was born in nineteen-oh-two in Hartford, Connecticut.

Barbara was the third of four children. Her family moved to the Brooklyn area

of New York City in nineteen-oh-eight. Barbara was an active child with

interests in sports and music. She also developed an interest in science.

She studied science at Cornell University in Ithaca, New York. Barbara was

among a small number of undergraduate students to receive training in

genetics in nineteen twenty-one. Years later, she noted⁵ that few college

students wanted to study genetics.

VOICE TWO:

In the early nineteen-twenties, genetics had not received widespread

acceptance as a subject. Only twenty years had passed since scientists re-

discovered the theories of heredity. Gregor Mendel proposed these ideas after

completing a series of experiments with plants. His experiments helped

scientists better understand how genes operate. They showed how genetic⁴

qualities are passed to living things from their ancestors.

VOICE ONE:

Barbara McClintock decided⁶ to study botany, the scientific study of plants,

at Cornell University. She completed her undergraduate studies in nineteen

twenty-three. McClintock decided to continue her education at Cornell. She

completed a master’s degree in nineteen twenty-five. Two years later, she

finished all her requirements for a doctorate⁷ degree.

In the late nineteen-twenties, McClintock joined several other students in a

group that studied genetics. The students included a future winner of the

Nobel Prize, George Beadle. Another was Marcus Rhoades. Years later, he would

become a leading expert in genetics.

McClintock said both men recognized the importance of exploring the

connection between genes and chromosomes.

McClintock stayed at Cornell after she completed her education. She taught

students botany. She also supervised genetic studies of the corn plant, or

maize⁸. She studied chromosomes, which are lines of genes. She made several

discoveries about genes and chromosomes.

VOICE TWO:

The nineteen thirties were not a good time to be a young scientist in the

United States. The country was in the middle of the great economic

depression. Millions of Americans were unemployed⁹. Male scientists were

offered jobs.  But female geneticists were not much in demand.

McClintock received two offers to travel and carry out research projects. The

first came from America’s National Research Council. She worked at several

places, including Cornell and the University of Missouri in Columbia. Later,

a group called the Guggenheim Foundation provided financial aid for her to

study in Germany. McClintock went to Berlin, but returned to Cornell the

following year. Her skills and work were widely praised. But she still was

unable to find a permanent job.

(MUSIC)

VOICE ONE:

For years, scientists had been using x-rays to study genetic material in

plants and other organisms. They found that x-rays caused genes to change.

Sometimes, the x-rays physically¹⁰ broke the chromosome². Genetic researchers

looked for changes in the organism. Then they used this information to

produce a map linking the changes to a single area of the chromosome.


McClintock became interested in the way genes reacted to unusual events. She

formed a successful working relationship with Lewis Stadler of the University

of Missouri. He had demonstrated the effects of x-rays on corn.


Stadler sent maize treated with radiation to McClintock. She identified

unusual areas she called ring chromosomes. She believed they were chromosomes

broken by radiation. The broken ends sometimes joined together and formed a

circle, or ring. This led her to believe that a structure at the end of the

chromosome prevents chromosomes from changing. She called this structure the

telomere. #p#副标题#e#


VOICE TWO:

Stadler got the University of Missouri to offer a permanent position to

McClintock in nineteen thirty-six. She became an assistant professor. During

her time at the university, she worked with plants treated with x-rays. She

also discovered plants with chromosomes that broke without help of radiation.

She described this activity as the breakage-fusion-bridge cycle.

University officials and professors recognized the importance of McClintock’

s research. Yet she believed that she was not able to make progress in her

position. So she decided to leave the University of Missouri.

(MUSIC)

VOICE ONE:

An old friend from Cornell, Marcus Rhoades, invited McClincock to spend the

summer of nineteen forty-one working at the Cold Spring Harbor Laboratory. It

is a research center on Long Island, near New York City.

McClintock started in a temporary job with the genetics department. A short

time later, she accepted a permanent position with the laboratory. This gave

her the freedom to continue her research without having to teach or

repeatedly ask for financial aid.


At Cold Spring Harbor Laboratory, McClintock continued her work with the

breakage-fusion-bridge cycle. She found that some corn plant genes acted in

an unusual way. They appeared to move from cell to cell during development of

corn particles, or kernels¹¹. She discovered that the genes moved on and

between chromosomes.

VOICE TWO:

McClintock confirmed her discovery and extended her observations for six

years. The changes could not be explained by any known theory. So, she

developed her own theory. She believed the moveable genes were not genes at

all, but genetic controllers or controlling elements. She said they

influenced the actions of other genes.

During this period, McClintock was elected to the National Academy of

Sciences. She was the third woman ever so honored. She also was named

president of the Genetics Society of America.

VOICE ONE:

In nineteen fifty-one, McClintock was asked to present her findings at a

conference held at Cold Spring Harbor Laboratory. Her report described the

movement of genes from one part of a chromosome to another. She used the

presentation to discuss her ideas of controlling elements in genes.


The other scientists reacted to her ideas with a mixture of criticism and

silence. Most scientists believed that genes did not move. Few people seemed

to accept her findings. Yet others argued that her experiments were complex

and difficult to explain, even to other scientists. They said she would not

have been invited to speak unless conference organizers understood some of

the importance of her work.

(MUSIC)

VOICE TWO:

For years, many scientists dismissed McClintock’s findings. During this

period, she continued doing her own work and reaching her own findings.

Beginning in the late nineteen-fifties, she went to Central and South America

to study different kinds of maize plants. She examined the development of

agricultural maize by native peoples. She also assisted younger scientists

and students in genetics.

Her work at the Cold Spring Harbor Laboratory was recognized in nineteen

seventy. She was given the American government’s highest science award –

the National Medal of Science.

VOICE ONE:

By the nineteen-seventies, newly developed methods of molecular¹² biology

confirmed what McClintock had learned through observation. Her discoveries

have had an effect on everything from genetic engineering to cancer research.

McClintock won the Nobel Prize for Physiology¹³ or Medicine in nineteen eighty

-three for her discovery of the ability of genes to change positions on

chromosomes. She was the first American woman to win an unshared Nobel Prize.

Barbara McClintock remained at Cold Spring Harbor for the rest of her life.

She died in nineteen ninety-two. She was ninety years old.

(THEME)

VOICE TWO:

This program was written by George Grow. Lawan Davis was our producer. I’m

Barbara Klein.

VOICE ONE:

And I’m Doug Johnson. Join us again next week for PEOPLE IN AMERICA in VOA

Special English.