Esther Lederberg facts for kids
Quick facts for kids
Esther Lederberg
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Stanford University laboratory
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Esther Miriam Zimmer
December 18, 1922 Bronx, New York, U.S.
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| Died | November 11, 2006 (aged 83) Stanford, California, U.S.
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| Alma mater | Hunter College, Stanford University, University of Wisconsin |
| Known for | Lambda phage, specialized transduction, replica plating, fertility factor F, Plasmid Reference Center |
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| Awards | Pasteur Award, Dernham Postdoctoral Fellowship in Oncology, President of the Stanford Chapter of Sigma Xi |
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| Fields | Microbiology Microbial Genetics |
| Institutions | Stanford University University of Wisconsin |
| Doctoral advisor | R. A. Brink |
Esther Miriam Zimmer Lederberg (born December 18, 1922 – died November 11, 2006) was an American microbiologist. She was a very important scientist in the early days of bacterial genetics, which is the study of how bacteria pass on their traits.
Esther Lederberg made several big discoveries. She found a special kind of bacterial virus called λ. She also discovered the bacterial fertility factor F, which helps bacteria share genetic material. She also created the first successful way to do something called replica plating. This method helped scientists understand how genes are transferred between bacteria through a process called specialized transduction.
Lederberg also started and ran the Plasmid Reference Center at Stanford University. Here, she kept, named, and shared many types of plasmids. Plasmids are small loops of DNA found in bacteria. These plasmids could carry genes for things like antibiotic resistance, resistance to heavy metals, and other important traits.
Even though she made huge discoveries, Esther Lederberg faced challenges. She was a woman in a field mostly led by men. Also, her husband, Joshua Lederberg, won a Nobel Prize for related work. Because of this, Esther often didn't get enough credit for her own important contributions. Many textbooks don't mention her work or give credit to her husband instead.
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Early Life and Education
Esther Miriam Zimmer was born in the Bronx, New York, in 1922. She was the first of two children in her family. Her father, David Zimmer, was an immigrant from Romania who owned a print shop. Her mother was Pauline Geller Zimmer. Esther grew up during the Great Depression, a time when many families struggled financially. She learned Hebrew and helped lead Passover dinners.
Esther went to Evander Childs High School in the Bronx. She graduated early in 1938, when she was just 15. She received a scholarship to attend Hunter College in New York City. At first, she wanted to study French or literature. However, she changed her mind and decided to study biochemistry. Her teachers thought it would be hard for a woman to have a science career, but she followed her passion.
While in college, she worked as a research assistant at the New York Botanical Garden. She studied a type of mold called Neurospora crassa. She earned her bachelor's degree in genetics in 1942, graduating with honors at age 19.
After college, Esther worked as a research assistant at the Carnegie Institution of Washington. She continued to study N. crassa. In 1944, she received a fellowship to Stanford University. There, she worked with famous scientists like George Wells Beadle and Edward Tatum. She earned her master's degree in genetics from Stanford in 1946. Her master's paper was about mutant strains of Neurospora.
In 1946, she married Joshua Lederberg, who was also a science student. Esther then moved to the University of Wisconsin when her husband became a professor there. She continued her studies and received a special fellowship from the National Cancer Institute. She finished her doctorate degree in 1950. Her main project was about how genes control changes in the bacterium Escherichia coli.
Key Discoveries in Genetics
Esther Lederberg stayed at the University of Wisconsin for most of the 1950s. During this time, she made her most important discoveries. She found lambda phage, studied how it relates to lysogeny (when a virus lives quietly inside a bacterium), and discovered the E. coli F fertility factor. She also worked with Joshua Lederberg to create the first successful replica plating method. Her work helped scientists understand specialized transduction, which is how bacteria share genes.
Her contributions were so important that she is seen as a pioneer in bacterial genetics. In 1956, Esther and Joshua Lederberg received the Pasteur Medal for their basic studies of bacterial genetics.
Discovering Lambda Bacteriophage
Esther Lederberg was the first person to find and isolate λ bacteriophage. She first announced her discovery in 1951 while still a PhD student. She later wrote a detailed paper about it in 1953. She was working with a strain of E. coli bacteria that had been treated with ultraviolet light. When she mixed this treated strain with the original E. coli strain, she saw clear spots called plaques on a special plate. These plaques are caused by bacteriophages.
She realized that the original E. coli strain contained the bacteriophage. The UV treatment had removed the bacteriophage from the mutant strain, making it sensitive to infection. She named this new bacteriophage λ. Her studies showed that λ could either quickly make many copies of itself and burst out of the E. coli host, or it could live quietly inside the E. coli as part of its genetic material.
Esther and Joshua Lederberg showed that λ, when it was quiet inside the bacterium, was located near the E. coli genes needed to use the sugar galactose. They suggested that the genetic material of λ actually joined with the bacterium's own DNA. It then copied itself along with the host's DNA. Sometimes, when the phage left the host DNA, it would take a piece of the host's DNA with it. This piece could then be carried to a new host bacterium by the phage. This process is called specialized transduction.
Lederberg shared her findings at international conferences. In 1957, she spoke about λ lysogeny and specialized transduction in Australia. In 1958, she presented her work on mapping the gal gene at a genetics conference in Canada.
Finding the Bacterial Fertility Factor F
Lederberg's discovery of the fertility factor (F factor) came from her experiments to map the location of lambda phage on the E. coli chromosome. She was trying to combine different E. coli strains. When some of her combinations didn't work, she thought that some of her E. coli strains might have lost a "fertility factor."
She explained it herself: "I explored the idea that there was some sort of 'fertility factor' which if missing, meant no combinations happened. For short, I named this F." Later, other scientists showed that the F factor is a piece of bacterial DNA. It contains genes that allow a bacterium to share DNA with another bacterium through direct contact. This process is called conjugation. The F factor can exist as a separate plasmid or become part of the bacterium's main chromosome.
Understanding How Mutations Happen
Scientists had been trying for years to find a good way to copy bacterial colonies from one plate to many others. Esther and Joshua Lederberg finally solved this problem with their replica plating method. Before this, people used less effective tools like toothpicks or paper.
It's thought that Esther's idea for replica plating might have come from watching her father use his printing press. She would press a plate of bacterial colonies onto a piece of sterile velvet. Then, she would stamp the velvet onto new plates that had different ingredients. This allowed researchers to easily study different traits of the bacteria.
The Lederbergs used replica plating to show that bacteria developed resistance to viruses and antibiotics even when those things weren't around. This proved that these changes (mutations) happened randomly, not because the bacteria were exposed to the virus or antibiotic. This idea had been shown before by other scientists, but their mathematical arguments were hard to understand. The Lederbergs' simple replica-plating experiment helped everyone clearly see how it worked.
Challenges as a Woman Scientist
Stanley Falkow, another microbiologist, said that Esther Lederberg was "a genius in the lab" when it came to experiments. However, even with her amazing discoveries, Esther Lederberg faced many difficulties as a woman scientist in the 1950s and 1960s.
After her big discoveries of the F factor and λ in graduate school, Joshua Lederberg, who was her advisor, stopped her from doing more experiments on them. He wanted her to finish her PhD. This delay might have hurt her chances of getting full recognition for her work as an independent scientist. Because of this, her findings on bacterial conjugation are often mainly credited to her husband. Many science textbooks focus on Joshua Lederberg's role in discoveries they made together. The fact that she doesn't get enough credit for replica plating is an example of the Matilda effect. This is when discoveries made by women scientists are unfairly given credit to their male colleagues.
When Joshua Lederberg won the Nobel Prize in 1958, universities looking to hire him often saw Esther as just his wife and assistant, not as an important scientist on her own.
Esther Lederberg was also not asked to write a chapter in a major book about molecular biology in 1966. A science historian said this was "unthinkable" because of her important work with bacteriophages. This was partly due to the unfair treatment of women in science during that time.
Luigi Luca Cavalli-Sforza, who worked with them, wrote that Esther Lederberg "has enjoyed the privilege of working with a very famous husband. This has been at times also a setback, because inevitably she has not been credited with as much of the credit as she really deserved." Joshua Lederberg did acknowledge her work at times. For example, at a conference in 1951, he talked about her doctoral work and listed her as a co-author. However, he didn't always give her credit later, like in his own story about their discovery of genetic recombination.
Esther Lederberg stood up for herself and other women scientists. At Stanford University, where her husband became the head of the genetics department in 1959, she and two other women spoke to the dean about the lack of women professors. She eventually got a faculty position as a Research Associate Professor in microbiology, but it was not a permanent job. After she divorced Joshua, she had to fight to keep her job at Stanford. Later, in 1974, she was moved to a lower position that depended on her getting grant money.
Other Interests
Esther Lederberg loved music throughout her life. She especially enjoyed playing medieval, Renaissance, and baroque music on old instruments. She played the recorder. In 1962, she started the Mid-Peninsula Recorder Orchestra, which plays music from the 13th century to today.
Lederberg also loved the books of Charles Dickens and Jane Austen. She was a member of groups that studied and celebrated these authors.
Personal Life
Esther married Joshua Lederberg in 1946. They divorced in 1968. In 1989, she met Matthew Simon, an engineer who also loved early music. They married in 1993 and stayed together until her death.
She passed away in Stanford, California, on November 11, 2006, at the age of 83. She died from pneumonia and heart failure.
See also
In Spanish: Esther Lederberg para niños
