Rachel Louise Carson (May 27, 1907 - April 14, 1964)

Rachel Carson, writer, scientist, and ecologist, grew up simply in the rural river town of Springdale, Pennsylvania. Her mother bequeathed to her a life-long love of nature and the living world that Rachel expressed first as a writer and later as a student of marine biology. Carson graduated from Pennsylvania College for Women (now Chatham College) in 1929, studied at the Woods Hole Marine Biological Laboratory, and received her MA in zoology from Johns Hopkins University in 1932.

She was hired by the U.S. Bureau of Fisheries to write radio scripts during the Depression and supplemented her income writing feature articles on natural history for the Baltimore Sun. She began a fifteen-year career in the federal service as a scientist and editor in 1936 and rose to become Editor-in-Chief of all publications for the U. S. Fish and Wildlife Service.

PHOTO: Rachel CarsonShe wrote pamphlets on conservation and natural resources and edited scientific articles, but in her free time turned her government research into lyric prose, first as an article "Undersea" (1937, for the Atlantic Monthly), and then in a book, Under the Sea-wind (1941). In 1952 she published her prize-winning study of the ocean, The Sea Around Us, which was followed by The Edge of the Sea in 1955. These books constituted a biography of the ocean and made Carson famous as a naturalist and science writer for the public. Carson resigned from government service in 1952 to devote herself to her writing.

She wrote several other articles designed to teach people about the wonder and beauty of the living world, including "Help Your Child to Wonder," (1956) and "Our Ever-Changing Shore" (1957), and planned another book on the ecology of life. Embedded within all of Carson's writing was the view that human beings were but one part of nature distinguished primarily by their power to alter it, in some cases irreversibly. PHOTO: Rachel Carson

Disturbed by the profligate use of synthetic chemical pesticides after World War II, Carson reluctantly changed her focus in order to warn the public about the long term effects of misusing pesticides. In Silent Spring (1962) she challenged the practices of agricultural scientists and the government, and called for a change in the way humankind viewed the natural world.

Carson was attacked by the chemical industry and some in government as an alarmist, but courageously spoke out to remind us that we are a vulnerable part of the natural world subject to the same damage as the rest of the ecosystem. Testifying before Congress in 1963, Carson called for new policies to protect human health and the environment. Rachel Carson died in 1964 after a long battle against breast cancer. Her witness for the beauty and integrity of life continues to inspire new generations to protect the living world and all its creatures.

Rosalind Elsie Franklin (July 25, 1920 – April 16, 1958)

There is probably no other woman scientist with as much controversy surrounding her life and work as Rosalind Franklin. Franklin was responsible for much of the research and discovery work that led to the understanding of the structure of deoxyribonucleic acid, DNA. The story of DNA is a tale of competition and intrigue, told one way in James Watson's book The Double Helix, and quite another in Anne Sayre's study, Rosalind Franklin and DNA. James Watson, Francis Crick, and Maurice Wilkins received a Nobel Prize for the double-helix model of DNA in 1962, four years after Franklin's death at age 37 from ovarian cancer.

Franklin excelled at science and attended one of the few girls' schools in London that taught physics and chemistry. When she was 15, she decided to become a scientist. Her father was decidedly against higher education for women and wanted Rosalind to be a social worker. Ultimately he relented, and in 1938 she enrolled at Newnham College, Cambridge, graduating in 1941. She held a graduate fellowship for a year, but quit in 1942 to work at the British Coal Utilization Research Association, where she made fundamental studies of carbon and graphite microstructures. This work was the basis of her doctorate in physical chemistry, which she earned from Cambridge University in 1945.

After Cambridge, she spent three productive years (1947-1950) in Paris at the Laboratoire Central des Services Chimiques de L'Etat, where she learned X-ray diffraction techniques. In 1951, she returned to England as a research associate in John Randall's laboratory at King's College, London.

It was in Randall's lab that she crossed paths with Maurice Wilkins. She and Wilkins led separate research groups and had separate projects, although both were concerned with DNA. When Randall gave Franklin responsibility for her DNA project, no one had worked on it for months. Wilkins was away at the time, and when he returned he misunderstood her role, behaving as though she were a technical assistant. Both scientists were actually peers. His mistake, acknowledged but never overcome, was not surprising given the climate for women at the university then. Only males were allowed in the university dining rooms, and after hours Franklin's colleagues went to men-only pubs.

But Franklin persisted on the DNA project. J. D. Bernal called her X-ray photographs of DNA, "the most beautiful X-ray photographs of any substance ever taken." Between 1951 and 1953 Rosalind Franklin came very close to solving the DNA structure. She was beaten to publication by Crick and Watson in part because of the friction between Wilkins and herself. At one point, Wilkins showed Watson one of Franklin's crystallographic portraits of DNA. When he saw the picture, the solution became apparent to him, and the results went into an article in Nature almost immediately. Franklin's work did appear as a supporting article in the same issue of the journal.

A debate about the amount of credit due to Franklin continues. What is clear is that she did have a meaningful role in learning the structure of DNA and that she was a scientist of the first rank. Franklin moved to J. D. Bernal's lab at Birkbeck College, where she did very fruitful work on the tobacco mosaic virus. She also began work on the polio virus. In the summer of 1956, Rosalind Franklin became ill with cancer. She died less than two years later.

Marie Skłodowska-Curie (November 7, 1867 – July 4, 1934)

Marie Curie, née Maria Sklodowska, was born in Warsaw on November 7, 1867, the daughter of a secondary-school teacher. She received a general education in local schools and some scientific training from her father. She became involved in a students' revolutionary organization and found it prudent to leave Warsaw, then in the part of Poland dominated by Russia, for Cracow, which at that time was under Austrian rule. In 1891, she went to Paris to continue her studies at the Sorbonne where she obtained Licenciateships in Physics and the Mathematical Sciences. She met Pierre Curie, Professor in the School of Physics, in 1894 and in the following year they were married. She succeeded her husband as Head of the Physics Laboratory at the Sorbonne, gained her Doctor of Science degree in 1903, and following the tragic death of Pierre Curie in 1906, she took his place as Professor of General Physics in the Faculty of Sciences, the first time a woman had held this position. She was also appointed Director of the Curie Laboratory in the Radium Institute of the University of Paris, founded in 1914.

Her early researches, together with her husband, were often performed under difficult conditions, laboratory arrangements were poor and both had to undertake much teaching to earn a livelihood. The discovery of radioactivity by Henri Becquerel in 1896 inspired the Curies in their brilliant researches and analyses which led to the isolation of polonium, named after the country of Marie's birth, and radium. Mme. Curie developed methods for the separation of radium from radioactive residues in sufficient quantities to allow for its characterization and the careful study of its properties, therapeutic properties in particular.

Mme. Curie throughout her life actively promoted the use of radium to alleviate suffering and during World War I, assisted by her daughter, Iréne, she personally devoted herself to this remedial work. She retained her enthusiasm for science throughout her life and did much to establish a radioactivity laboratory in her native city - in 1929 President Hoover of the United States presented her with a gift of $50,000 donated by American friends of science, to purchase radium for use in the laboratory in Warsaw.

Mme. Curie, quiet, dignified and unassuming, was held in high esteem and admiration by scientists throughout the world. She was a member of the Conseil du Physique Solvay from 1911 until her death and since 1922 she had been a member of the Committee of Intellectual Co-operation of the League of Nations. Her work is recorded in numerous papers in scientific journals and she is the author of Recherches sur les Substances Radioactives (Investigations on radioactive substances) (1904), L'Isotopie et les Eléments Isotopes (Isotopy and isotopic elements) and the classic Traité de radioactivité (Treatise on radioactivity) (1910).

The importance of Mme. Curie's work is reflected in the numerous awards bestowed on her. She received many honorary science, medicine and law degrees and honorary memberships of learned societies throughout the world. Together with her husband, she was awarded half of the Nobel Prize for Physics in 1903, for their study into the spontaneous radiation discovered by Becquerel, who was awarded the other half of the Prize. In 1911 she received a second Nobel Prize, this time in Chemistry, in recognition of her work in radioactivity. She also received, jointly with her husband, the Davy Medal of the Royal Society in 1903 and, in 1921, President Harding of the United States, on behalf of the women of America, presented her with one gram of radium in recognition of her service to science.

The Curie's elder daughter, Iréne, married Frédéric Joliot in 1926 and they were joint recipients of the Nobel Prize for Chemistry in 1935. The younger daughter, Eve, married the American diplomat H.R. Labouisse. They have both taken lively interest in social problems, and as Director of the United Nations' Children's Fund he received on its behalf the Nobel Peace Prize in Oslo in 1965. She is the author of a famous biography of her mother, Madame Curie (Gallimard, Paris, 1938), translated into several languages.

Mme. Curie died in Savoy, France, after a short illness, on July 4, 1934.

Barbara McClintock (June 16, 1902 – September 2, 1992)

Barbara McClintock (June 16, 1902 – September 2, 1992), was an American scientist and one of the world's most distinguished cytogeneticists, the 1983 Nobel laureate in Physiology or Medicine. McClintock received her PhD in botany from Cornell University in 1927. There she started her career as the leader in the development of maize cytogenetics, the focus of her research for the rest of her life. From the late 1920s, McClintock studied chromosomes and how they change during reproduction in maize. Her work was groundbreaking; she developed the technique for visualizing maize chromosomes and used microscopic analysis to demonstrate many fundamental genetic ideas. One of those ideas was the notion of genetic recombination by crossing-over during meiosis—a mechanism by which chromosomes exchange information. She produced the first genetic map for maize, linking regions of the chromosome to physical traits. She demonstrated the role of the telomere and centromere, regions of the chromosome that are important in the conservation of genetic information. She was recognized among the best in the field, awarded prestigious fellowships, and elected a member of the National Academy of Sciences in 1944.

During the 1940s and 1950s, McClintock discovered transposition and used it to demonstrate that genes are responsible for turning physical characteristics on and off. She developed theories to explain the suppression and expression of genetic information from one generation of maize plants to the next. Due to skepticism of her research and its implications, she stopped publishing her data in 1953.

Later, she made an extensive study of the cytogenetics and ethnobotany of maize races from South America. McClintock's research became well understood in the 1960s and 1970s, as other scientists confirmed the mechanisms of genetic change and genetic regulation that she had demonstrated in her maize research in the 1940s and 1950s. Awards and recognition for her contributions to the field followed, including the Nobel Prize for Physiology or Medicine, awarded to her in 1983 for the discovery of genetic transposition; she is the only woman to receive an unshared Nobel Prize in that category.

Barbara McClintock was born Eleanor McClintock on June 16, 1902 in Hartford, Connecticut, the third of four children born to physician Thomas Henry McClintock and Sara Handy McClintock. Thomas McClintock was the child of British immigrants, and Sara Handy, born Grace, descended from an old American Mayflower family. Marjorie, the oldest child, was born in October 1898; Mignon, the second daughter, was born in November 1900. The youngest, Malcolm Rider (called Tom), was born 18 months after Barbara. As a young girl, her parents determined that Eleanor, a "feminine" and "delicate" name, was not appropriate for her, and chose Barbara instead. McClintock was an independent child beginning at a very young age, a trait she later identified as her "capacity to be alone". From the age of three until she began school, McClintock lived with an aunt and uncle in Brooklyn, New York in order to reduce the financial burden on her parents while her father established his medical practice. She was described as a solitary and independent child, and a tomboy. She was close to her father, but had a difficult relationship with her mother, tension that began when she was young.

The McClintock family moved to Brooklyn in 1908 and McClintock completed her secondary education there at Erasmus Hall High School; she graduated early in 1919. She discovered her love of science and reaffirmed her solitary personality during high school. She wanted to continue her studies at Cornell University's College of Agriculture. Her mother resisted sending McClintock to college, for fear that she would be unmarriageable. McClintock was almost prevented from starting college, but her father intervened just before registration began, and she matriculated at Cornell in 1919.

McClintock began her studies at Cornell's College of Agriculture in 1919. There, she participated in student government and was invited to join a sorority, though she soon realized that she preferred not to join formal organizations. Instead, McClintock took up music, specifically jazz. She studied botany, receiving a BSc in 1923. Her interest in genetics began when she took her first course in that field in 1921. The course was based on a similar one offered at Harvard University, and was taught by C. B. Hutchison, a plant breeder and geneticist. Hutchison was impressed by McClintock's interest, and telephoned to invite her to participate in the graduate genetics course at Cornell in 1922. McClintock pointed to Hutchison's invitation as the reason she continued in genetics: "Obviously, this telephone call cast the die for my future. I remained with genetics thereafter." Although it has been reported that women could not major in genetics at Cornell, and therefore her MA and PhD—earned in 1925 and 1927, respectively—were officially awarded in botany, recent research has revealed that women did earn graduate degrees in Cornell's Plant Breeding Department during the time that McClintock was a student at Cornell.

During her graduate studies and postgraduate appointment as a botany instructor, McClintock was instrumental in assembling a group that studied the new field of cytogenetics in maize. This group brought together plant breeders and cytologists, and included Marcus Rhoades, future Nobel laureate George Beadle, and Harriet Creighton. Rollins A. Emerson, head of the Plant Breeding Department, supported these efforts, although he was not a cytologist himself.

McClintock's cytogenetic research focused on developing ways to visualize and characterize maize chromosomes. This particular part of her work influenced a generation of students, as it was included in most textbooks. She also developed a technique using carmine staining to visualize maize chromosomes, and showed for the first time the morphology of the 10 maize chromosomes. This discovery was made because she observed cells from the microspore as opposed to the root tip. By studying the morphology of the chromosomes, McClintock was able to link specific chromosome groups of traits that were inherited together. Marcus Rhoades noted that McClintock's 1929 Genetics paper on the characterization of triploid maize chromosomes triggered scientific interest in maize cytogenetics, and attributed to her 10 of the 17 significant advances in the field that were made by Cornell scientists between 1929 and 1935.

In 1930, McClintock was the first person to describe the cross-shaped interaction of homologous chromosomes during meiosis. The following year, McClintock and Creighton proved the link between chromosomal crossover during meiosis and the recombination of genetic traits. They observed how the recombination of chromosomes seen under a microscope correlated with new traits. Until this point, it had only been hypothesized that genetic recombination could occur during meiosis, although it had been shown genetically. McClintock published the first genetic map for maize in 1931, showing the order of three genes on maize chromosome 9. This information provided necessary data for the crossing-over study she published with Creighton; they also showed that crossing-over occurs in sister chromatids as well as homologous chromosomes. In 1938, she produced a cytogenetic analysis of the centromere, describing the organization and function of the centromere, as well as the fact that it can divide.

McClintock's breakthrough publications, and support from her colleagues, led to her being awarded several postdoctoral fellowships from the National Research Council. This funding allowed her to continue to study genetics at Cornell, the University of Missouri, and the California Institute of Technology, where she worked with E. G. Anderson. During the summers of 1931 and 1932, she worked at Missouri with geneticist Lewis Stadler, who introduced her to the use of X-rays as a mutagen. Exposure to X-rays can increase the rate of mutation above the natural background level, making it a powerful research tool for genetics. Through her work with X-ray-mutagenized maize, she identified ring chromosomes, which form when the ends of a single chromosome fuse together after radiation damage. From this evidence, McClintock hypothesized that there must be a structure on the chromosome tip that would normally ensure stability. She showed that the loss of ring-chromosomes at meiosis caused variegation in maize foliage in generations subsequent to irradiation resulting from chromosomal deletion. During this period, she demonstrated the presence of the nucleolus organizer region on a region on maize chromosome 6, which is required for the assembly of the nucleolus. In 1933, she established that cells can be damaged when nonhomologous recombination occurs. During this same period, McClintock hypothesized that the tips of chromosomes are protected by telomeres.

McClintock received a fellowship from the Guggenheim Foundation that made possible six months of training in Germany during 1933 and 1934. She had planned to work with Curt Stern, who had demonstrated crossing-over in Drosophila just weeks after McClintock and Creighton had done so; however, Stern emigrated to the United States. Instead, she worked with geneticist Richard B. Goldschmidt, who was the head of the Kaiser Wilhelm Institute. She left Germany early amidst mounting political tension in Europe, and returned to Cornell, remaining there until 1936, when she accepted an Assistant Professorship offered to her by Lewis Stadler in the Department of Botany at the University of Missouri-Columbia. While still at Cornell, she was supported by a two-year Rockefeller Foundation grant obtained for her through Emerson's efforts.

During her time at Missouri, McClintock expanded her research on the effect of X-rays on maize cytogenetics. McClintock observed the breakage and fusion of chromosomes in irradiated maize cells. She was also able to show that, in some plants, spontaneous chromosome breakage occurred in the cells of the endosperm. Over the course of mitosis, she observed that the ends of broken chromatids were rejoined after the chromosome replication. In the anaphase of mitosis, the broken chromosomes formed a chromatid bridge, which was broken when the chromatids moved towards the cell poles. The broken ends were rejoined in the interphase of the next mitosis, and the cycle was repeated, causing massive mutation, which she could detect as variegation in the endosperm. This breakage–rejoining–bridge cycle was a key cytogenetic discovery for several reasons. First, it showed that the rejoining of chromosomes was not a random event, and second, it demonstrated a source of large-scale mutation. For this reason, it remains an area of interest in cancer research today.

Although her research was progressing at Missouri, McClintock was not satisfied with her position at the University. She recalled being excluded from faculty meetings, and was not made aware of positions available at other institutions. In 1940, she wrote to Charles Burnham, "I have decided that I must look for another job. As far as I can make out, there is nothing more for me here. I am an assistant professor at $3,000 and I feel sure that that is the limit for me." Initially, McClintock's position was created especially for her by Stadler, and might have depended on his presence at the university. McClintock believed she would not gain tenure at Missouri, even though according to some accounts, she knew she would be offered a promotion from Missouri in the spring of 1942. Recent evidence reveals that McClintock more likely decided to leave Missouri because she had lost trust in her employer and in the University administration, after discovering that her job would be in jeopardy if Stadler were to leave for Caltech, as he had considered doing. The university's retaliation against Stadler amplified her sentiments.

In early 1941, she took a leave of absence from Missouri in hopes of finding a position elsewhere. She accepted a visiting Professorship at Columbia University, where her former Cornell colleague Marcus Rhoades was a professor. Rhoades also offered to share his research field at Cold Spring Harbor on Long Island. In December 1941, she was offered a research position by Milislav Demerec, the newly appointed acting director of the Carnegie Institution of Washington's Department of Genetics Cold Spring Harbor Laboratory; McClintock accepted his invitation despite her qualms and became a permanent member of the faculty.

After her year-long temporary appointment, McClintock accepted a full-time research position at Cold Spring Harbor Laboratory. There, she was highly productive and continued her work with the breakage-fusion-bridge cycle, using it to substitute for X-rays as a tool for mapping new genes. In 1944, in recognition of her prominence in the field of genetics during this period, McClintock was elected to the National Academy of Sciences—only the third woman to be elected. That same year, she became the first female president of the Genetics Society of America; she was elected its vice-president in 1939. In 1944 she undertook a cytogenetic analysis of Neurospora crassa at the suggestion of George Beadle, who used the fungus to demonstrate the one gene–one enzyme relationship. He invited her to Stanford to undertake the study. She successfully described the number of chromosomes, or karyotype, of N. crassa and described the entire life cycle of the species. N. crassa has since become a model species for classical genetic analysis.

The relationship of Ac/Ds in the control of the elements and mosaic color of maize. The seed in 10 is colorless, there is no Ac element present and Ds inhibits the synthesis of colored pigments called anthocyanins. In 11 to 13, one copy of Ac is present. Ds can move and some anthocyanin is produced, creating a mosaic pattern. In the kernel in panel 14 there are two Ac elements and in 15 there are three.

In the summer of 1944 at Cold Spring Harbor Laboratory, McClintock began systematic studies on the mechanisms of the mosaic color patterns of maize seed and the unstable inheritance of this mosaicism. She identified two new dominant and interacting genetic loci that she named Dissociator (Ds) and Activator (Ac). She found that the Dissociator did not just dissociate or cause the chromosome to break, it also had a variety of effects on neighboring genes when the Activator was also present, which included making certain stable mutations unstable. In early 1948, she made the surprising discovery that both Dissociator and Activator could transpose, or change position, on the chromosome.

She observed the effects of the transposition of Ac and Ds by the changing patterns of coloration in maize kernels over generations of controlled crosses, and described the relationship between the two loci through intricate microscopic analysis. She concluded that Ac controls the transposition of the Ds from chromosome 9, and that the movement of Ds is accompanied by the breakage of the chromosome. When Ds moves, the aleurone-color gene is released from the suppressing effect of the Ds and transformed into the active form, which initiates the pigment synthesis in cells. The transposition of Ds in different cells is random, it may move in some but not others, which causes color mosaicism. The size of the colored spot on the seed is determined by stage of the seed development during dissociation. McClintock also found that the transposition of Ds is determined by the number of Ac copies in the cell.

Between 1948 and 1950, she developed a theory by which these mobile elements regulated the genes by inhibiting or modulating their action. She referred to Dissociator and Activator as "controlling units"—later, as "controlling elements"—to distinguish them from genes. She hypothesized that gene regulation could explain how complex multicellular organisms made of cells with identical genomes have cells of different function. McClintock's discovery challenged the concept of the genome as a static set of instructions passed between generations. In 1950, she reported her work on Ac/Ds and her ideas about gene regulation in a paper entitled "The origin and behavior of mutable loci in maize" published in the journal Proceedings of the National Academy of Sciences. In summer 1951, when she reported her work on the origin and behavior of mutable loci in maize at the annual symposium at Cold Spring Harbor Laboratory, presenting a paper of the same name. The paper delved into the instability caused by Dc and As or just As in four genes, along with the tendency of those genes to unpredictably revert to the wild phenotype. She also identified "families" of transposons, which did not interact with one another.

Her work on controlling elements and gene regulation was conceptually difficult and was not immediately understood or accepted by her contemporaries; she described the reception of her research as "puzzlement, even hostility". Nevertheless, McClintock continued to develop her ideas on controlling elements. She published a paper in Genetics in 1953, where she presented all her statistical data, and undertook lecture tours to universities throughout the 1950s to speak about her work. She continued to investigate the problem and identified a new element that she called Suppressor-mutator (Spm), which, although similar to Ac/Ds, acts in a more complex manner. Like Ac/Ds, some versions could transpose on their own and some could not; unlike Ac/Ds, when present, it fully suppressed the expression of mutant genes when they normally would not be entirely suppressed. Based on the reactions of other scientists to her work, McClintock felt she risked alienating the scientific mainstream, and from 1953 stopped publishing accounts of her research on controlling elements.

McClintock's microscope and ears of corn on exhibition at the National Museum of Natural History
In 1957, McClintock received funding from the National Academy of Sciences to start research on indigenous strains of maize in Central America and South America. She was interested in studying the evolution of maize through chromosomal changes, and being in South America would allow her to work on a larger scale. McClintock explored the chromosomal, morphological, and evolutionary characteristics of various races of maize. After extensive work in the 1960s and 1970s, McClintock and her collaborators published the seminal study The Chromosomal Constitution of Races of Maize, leaving their mark on paleobotany, ethnobotany, and evolutionary biology.

McClintock officially retired from her position at the Carnegie Institution in 1967, and was made a Distinguished Service Member of the Carnegie Institution of Washington. This honor allowed her to continue working with graduate students and colleagues in the Cold Spring Harbor Laboratory as scientist emerita; she lived in the town. In reference to her decision 20 years earlier to stop publishing detailed accounts of her work on controlling elements, she wrote in 1973:

"Over the years I have found that it is difficult if not impossible to bring to consciousness of another person the nature of his tacit assumptions when, by some special experiences, I have been made aware of them. This became painfully evident to me in my attempts during the 1950s to convince geneticists that the action of genes had to be and was controlled. It is now equally painful to recognize the fixity of assumptions that many persons hold on the nature of controlling elements in maize and the manners of their operation. One must await the right time for conceptual change."

The importance of McClintock's contributions was revealed in the 1960s, when the work of French geneticists Francois Jacob and Jacques Monod described the genetic regulation of the lac operon, a concept she had demonstrated with Ac/Ds in 1951. Following Jacob and Monod's 1961 Journal of Molecular Biology paper "Genetic regulatory mechanisms in the synthesis of proteins", McClintock wrote an article for American Naturalist comparing the lac operon and her work on controlling elements in maize. McClintock's contribution to biology is still not widely acknowledged as amounting to the discovery of genetic regulation.

McClintock was widely credited for discovering transposition after other researchers finally discovered the process in bacteria, yeast, and bacteriophages in the late 1960s and early 1970s. During this period, molecular biology had developed significant new technology, and scientists were able to show the molecular basis for transposition. In the 1970s, Ac and Ds were cloned by other scientists and were shown to be Class II transposons. Ac is a complete transposon that can produce a functional transposase, which is required for the element to move within the genome. Ds has a mutation in its transposase gene, which means that it cannot move without another source of transposase. Thus, as McClintock observed, Ds cannot move in the absence of Ac. Spm has also been characterized as a transposon. Subsequent research has shown that transposons typically do not move unless the cell is placed under stress, such as by irradiation or the breakage-fusion-bridge cycle, and thus their activation during stress can serve as a source of genetic variation for evolution. McClintock understood the role of transposons in evolution and genome change well before other researchers grasped the concept. Nowadays, Ac/Ds is used as a tool in plant biology to generate mutant plants used for the characterization of gene function.

In 1947, McClintock received the Achievement Award from the American Association of University Women. She was elected a Fellow of the American Academy of Arts and Sciences in 1959. In 1967, McClintock was awarded the Kimber Genetics Award; three years later, she was given the National Medal of Science by Richard Nixon in 1970. Cold Spring Harbor named a building in her honor in 1973. She received the Louis and Bert Freedman Foundation Award and the Lewis S. Rosensteil Award in 1978. In 1981, she became the first recipient of the MacArthur Foundation Grant, and was awarded the Albert Lasker Award for Basic Medical Research, the Wolf Prize in Medicine and the Thomas Hunt Morgan Medal by the Genetics Society of America. In 1982, she was awarded the Louisa Gross Horwitz Prize from Columbia University for her research in the "evolution of genetic information and the control of its expression."

Most notably, she received the Nobel Prize for Physiology or Medicine in 1983, the first woman to win that prize unshared, credited by the Nobel Foundation for discovering "mobile genetic elements"; it was more than 30 years after she initially described the phenomenon of controlling elements. She was compared to Gregor Mendel in terms of her scientific career by the Swedish Academy of Sciences when she was awarded the Prize.

She was elected a Foreign Member of the Royal Society in 1989. McClintock received the Benjamin Franklin Medal for Distinguished Achievement in the Sciences of the American Philosophical Society in 1993. She was awarded 14 Honorary Doctor of Science degrees and an Honorary Doctor of Humane Letters. In 1986 she was inducted into the National Women's Hall of Fame. During her final years, McClintock led a more public life, especially after Evelyn Fox Keller's 1983 biography of her, A Feeling for the Organism, brought McClintock's story to the public. She remained a regular presence in the Cold Spring Harbor community, and gave talks on mobile genetic elements and the history of genetics research for the benefit of junior scientists. An anthology of her 43 publications The Discovery and Characterization of Transposable Elements: The Collected Papers of Barbara McClintock was published in 1987.

Since her death, McClintock has been the subject of the biography by science historian Nathaniel C. Comfort's The Tangled Field: Barbara McClintock's Search for the Patterns of Genetic Control. Comfort's biography contests some claims about McClintock, described as the "McClintock Myth", which he claims was perpetuated by the earlier biography by Keller. Keller's thesis was that McClintock was long ignored or met with derision because she was a woman working in the sciences. For example, when McClintock presented her findings that the genetics of maize did not conform to Mendelian distributions, geneticist Sewall Wright expressed the belief that she did not understand the underlying mathematics of her work, a belief he had expressed towards other women at the time. In addition, geneticist Lotte Auerbach recounted that Joshua Lederberg returned from a visit to McClintock's lab with the remark: 'By God, that woman is either crazy or a genius.' " As Auerbach tells it, McClintock had thrown Lederberg and his colleagues out after half an hour 'because of their arrogance. She was intolerant of arrogance ... She felt she had crossed a desert alone and no one had followed her.'"

Comfort, however, asserts that McClintock was well regarded by her professional peers, even in the early years of her career. Although Comfort argues that McClintock was not a victim of gender discrimination, she has been widely written about in the context of women's studies. Most recent biographical works on women in science feature accounts of her experience. She is held up as a role model for girls in such works of children's literature as Edith Hope Fine's Barbara McClintock, Nobel Prize Geneticist, Deborah Heiligman's Barbara McClintock: Alone in Her Field and Mary Kittredge's Barbara McClintock. A recent biography for young adults by Naomi Pasachoff, Barbara McClintock, Genius of Genetics, provides a new perspective, based on the current literature.

On May 4, 2005, the United States Postal Service issued the "American Scientists" commemorative postage stamp series, a set of four 37-cent self-adhesive stamps in several configurations. The scientists depicted were Barbara McClintock, John von Neumann, Josiah Willard Gibbs, and Richard Feynman. McClintock was also featured in a 1989 four-stamp issue from Sweden which illustrated the work of eight Nobel Prize-winning geneticists. A small building at Cornell University and a laboratory building at Cold Spring Harbor Laboratory were named for her. A street has been named after her in the new "Adlershof Development Society" science park in Berlin.

Some of McClintock's personality and scientific achievements were referred to in Jeffrey Eugenides's 2011 novel The Marriage Plot, which tells the story of a yeast geneticist named Leonard who suffers from bipolar disorder. He works at a laboratory loosely based on Cold Spring Harbor. The character reminiscent of McClintock is a reclusive geneticist at the fictional laboratory, who makes the same discoveries as her factual counterpart.

Rachel Zimmerman (1972 - Present)

Rachel Zimmerman born in Ontario Canada 1972, grew up an inquisitive young girl, with a role model of a mother. Linda Zimmerman was the founder and president of her own software company and gave Rachel inspiration to enter the field of technology. She was a young girl that liked girl scouts and science.

The turning point in her life came when in the sixth grade, while researching Keller and Braille, she stumbled across a book on Blissymbols. With the idea of a science fair coming soon, she dove into everything about the system Blissymbols, communication system for the severely disabled, and decided to research other methods to improve it’s accessibility. It was then, at the science fair at the age of 12, that she created the Blissymbol printer.

This new device used a software program to enable those using Blissymbol language to “talk” to each other and preform all the other types of communication through the computer. Until then the user needed another person to translate the symbols they would point out. With the new printer, she developed a tap pad that enabled the person to simply touch the board and the software would do the translating, transmitting the output in the language of the user’s choice onto a computer screen. When she initially presented the concept at a science fair, it received a silver medal and she went on to compete in the World Exhibition of Achievement of Young Inventors. The Blissymbols printer also ended up winning a silver medal at the Canada-wide contest. Rachel Zimmerman, along with her forward-thinking invention, were showcased when they won a VTV Television Youth Achievement Award. Rachel continues her passion for the sciences.

Today according to her Linkin profile, she attended Bradeis University and International Space University. She has worked for

• Outreach Specialist at NASA Jet Propulsion Laboratory

• Education Outreach Coordinator at Jet Propulsion Laboratory

Past

• Education and Outreach Specialist at California Institute of Technology (Caltech)

• Education and Outreach Coordinator at The Planetary Society

• Space Vision System Specialist at Canadian Space Agency

• Intern at NASA Ames Research Center

• Master of Space Studies student at International Space University

Rachel now works for NASA and still has the same concern for those who are not able-bodied. She is currently helping NASA mold their innovations to better fit the needs of disabled people. To this day she works on better forms of communications for the disabled. Below is and example of a tap=board used by those severely handicapped for communication, thanks to Rachel Zimmerman.

Eva Ekeblad (10 July 1724 – 15 May 1786)

Eva Ekeblad, née Eva De la Gardie, was a Swedish agronomist, scientist, Salonist and noble (Countess). Her most known discovery was to make flour and alcohol out of potatoes (1746). She was the first female member of the Royal Swedish Academy of Sciences (1748).

Life

Eva De la Gardie was born to statesman count Magnus Julius De la Gardie (1668–1741) and the amateur politician and salonist Hedvig Catharina Lilje.

Eva was at the age of 16 (1740) married to the statesman count Claes Claesson Ekeblad, and became the mother of seven children (one son and six daughters). The couple had a residence in Stockholm and an estate in Västergötland and belonged to the very highest circles of the Swedish nobility. Eva Ekeblad was renowned for her charity to the poor.

Her spouse was often absent, and Eva was responsible for the management for the estates and supervised the bailiffs and the country-assemblys of Mariedal and Stola Manor. In Stockholm, she hosted a culturel salon and was described as "one of few aristocratic ladies whose honour was considered untainted". The first concert performings of the mass music of Johan Helmich Roman were performed in her salon at the Ekeblad palace.

Scientific Activity

Ekeblad discovered how to make flour and alcohol out of potatoes (1746). She thereby made potatoes, a plant introduced in Sweden in 1658 but until then only cultivated in the greenhouses of the aristocracy, a part of the basic food supply. This greatly improved eating habits and reduced the hunger epidemics. Previously, alcohol had been made by wheat, rye and barley, but now, more of that could be saved to make bread instead.

She also discovered a method of bleaching cotton textile and yarn with soap (1751), and of replacing the dangerous ingredients in the cosmetics of the time by making powder from potatoes (1752). She was said to have advertised the use of potatoes by using the flowers of the plant as hair ornaments.

Eva wrote to the Royal Swedish Academy of Sciences about her first discovery in 1746. In 1748, she became the first woman elected to the Academy, although she never took part in any of the Academy's meeting. After 1751, the Academy came to refer to her as an honorary rather than a full member, as the statutes confined membership to men.

Rosalind Franklin (1920-1958)

Who do you think of when you think of DNA? Watson? Crick? How about Franklin?

Rosalind Franklin was, for too long, the overshadowed party in Watson and Crick's story of how they unraveled the structure of DNA. Franklin took the X-ray diffraction images of DNA that indicated its twisted, double-helical structure; without her precise lab work, attention to detail and thoughtful analysis, those X-ray images wouldn't have been worth a penny.

What's more, without those images Watson and Crick would not have been able to publish their notable 1953 paper on the structure of DNA. Those images, leaked to Watson and Crick by Franklin's lab partner, made the difference in the discovery...but not in the recognition.

In 1962, Watson and Crick won the Nobel Prize for their work on the structure of DNA; by then, Franklin had been dead for four years, a victim of ovarian cancer.