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"On the Replication of Desoxyribonucleic Acid (DNA)" (1954), by Max Delbruck
In 1954 Max Delbruck published On the Replication of Desoxyribonucleic Acid (DNA) to question the semi-conservative DNA replication mechanism proposed that James Watson and Francis Crick had proposed in 1953. In his article published in the Proceedings of the National Academy of Sciences, Delbrück offers an alternative DNA replication mechanism, later called dispersive replication. Unlike other articles before it, On the Replication presents ways to experimentally test different DNA replication theories.
Format: Articles
Subject: Publications
Beadle and Ephrussi Show that Something Besides Eye Tissue Determines Eye Color in Fruit Flies
In the 1930s, George Beadle and Boris Ephrussi discovered factors that affect eye colors in developing fruit flies. They did so while working at the California Institute of Technology in Pasadena, California. (1) They took optic discs (colored fuchsia in the image) from fruit fly larvae in the third instar stage of development. Had the flies not been manipulated, they would have developed into adults with vermilion eyes.
Format: Graphics
Subject: Experiments, Organisms
Beadle and Ephrussi’s Technique to Transplant Optic Discs between Fruit Fly Larvae
In 1935, George Beadle and Boris Ephrussi developed a technique to transplant optic discs between fruit fly larvae. They developed it while at the California Institute of Technology in Pasedena, California. Optic discs are tissues from which the adult eyes develop. Beadle and Ephrussi used their technique to study the development of the eye and eye pigment. (1) The experimenter dissects a donor larva, which is in the third instar stage of development, and removes the optic disc (colored red) with a micropipette.
Format: Graphics
Subject: Technologies, Experiments, Organisms
Beadle and Ephrussi's Transplantation Technique for Drosophila
Boris Ephrussi and George Wells Beadle developed a transplantation technique on flies, Drosophila melanogaster, which they described in their 1936 article A Technique of Transplantation for Drosophila. The technique of injecting a tissue from one fly larva into another fly larva, using a micropipette, to grow that tissue in the second larvae, was a means for investigating development of Drosophila. Through this technique, Beadle and Ephrussi studied the role of genes in embryological processes.
Format: Articles
Subject: Technologies
Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993)
In its 1993 decision Daubert v. Merrell Dow Pharmaceuticals, Inc., the US Supreme Court established the Daubert Standard for evaluating the admissibility of scientific knowledge as evidence in US federal courts. When it began in trial court, the case addressed whether or not Bendectin, an anti-nausea medication taken during pregnancy, caused birth defects. However, after the trial court dismissed the case for lack of admissible evidence, Daubert v. Merrell Dow Pharmaceuticals, Inc.
Format: Articles
Subject: Legal
Gail Roberta Martin (1944– )
In the twentieth and early twenty-first centuries, Gail Roberta Martin specialized in biochemistry and embryology, more specifically cellular communication and the development of organs. In 1981, she named any cell taken from inside a human embryo at the blastocyst stage an “embryonic stem cell”. During development, an embryo goes through the blastocyst stage just before it implants in the uterus. Embryonic stem cells are useful for experiments because they are self-renewing and able to develop into almost any cell type in the body.
Format: Articles
Subject: People
Embryo Blotting Paper Models
Anatomical models have always been a mainstay of descriptive embryology. As the training of embryologists grew in the late 1800s, so too did the need for large-scale teaching models. Embryo wax models, such as those made by Adolf Ziegler and Gustav Born, were popular in the latter part of the nineteenth century and the early twentieth century as a way to visualize, in three dimensions, the fine detail of embryos without the aid of a microscope.
Format: Articles
Subject: Technologies
Sergio Cereceda Stone (1942- )
Sergio Cereceda Stone was born 16 April 1942 in the coastal city of Valparaiso, Chile. Stone's mother Luz was a housewife and caretaker for Sergio and his younger brother Lionel; his father Sergio served among the country's twenty appellate court judges. In the early 1950s Stone's father relocated the family to Santiago to further his law career.
Format: Articles
Subject: People, Ethics, Reproduction
“A Proposed Structure for the Nucleic Acids” (1953) by Linus Pauling and Robert Brainard Corey
In February 1953, Linus Pauling and Robert Brainard Corey, two scientists working at the California Institute of Technology in Pasadena, California, proposed a structure for deoxyribonucleic acid, or DNA, in their article “A Proposed Structure for the Nucleic Acids,” henceforth “Nucleic Acids.” In the article, Pauling and Corey suggest a model for nucleic acids, including DNA, that consisted of three nucleic acid strands wound together in a triple helix.
Format: Articles
Subject: Publications
Menstrual Hygiene Management in Low-Income Countries
Menstrual hygiene management, or MHM, is a concept that concerns girls' and women’s access to the appropriate information and resources to manage menstruation. In December 2012, the Joint Monitoring Program, or JMP, was one of the first organizations to define MHM as a global development goal. Since then, other organizations like WaterAid and the United Nations have expanded MHM’s definition to include menstrual education that is biologically accurate and free of taboo and stigma.
Format: Articles
Subject: Processes
Evelyn Lorraine Rothman (1932–2007)
Evelyn Lorraine Rothman advocated for women’s reproductive rights and invented at-home kits for women’s health concerns in the late twentieth century in Los Angeles, California. Rothman provided women in the Los Angeles area with the means to perform self-examinations, pregnancy tests, and abortions on their own without assistance from a medical professional. Along with Carol Downer, Rothman cofounded the Federation of Feminist Health Centers in Los Angeles, California, and spent her career educating women on reproductive health.
Format: Articles
Subject: People
Oliver Allison Ryder III (1946– )
Oliver Allison Ryder studied chromosomal evolution and endangered species in efforts for wildlife conservation and preservation at the San Diego Zoo in San Diego, California. Throughout his career, Ryder studied breeding patterns of endangered species. He collected and preserved cells, tissues, and DNA from endangered and extinct species to store in the San Diego Frozen Zoo, a center for genetic research and development in San Diego, California.
Format: Articles
Subject: People
Equilibrium Density Gradient Centrifugation in Cesium Chloride Solutions Developed by Matthew Meselson and Franklin Stahl
Matthew Meselson, Franklin Stahl, and Jerome Vinograd, developed cesium chloride, or CsCl, density gradient centrifugation in the 1950s at the California Institute of Technology, or Caltech, in Pasadena, California. Density gradient centrifugation enables scientists to separate substances based on size, shape, and density. Meselson and Stahl invented a specific type of density gradient centrifugation, called isopycnic centrifugation that used a solution of cesium chloride to separate DNA molecules based on density alone.
Format: Articles
Subject: Technologies
Spemann-Mangold Organizer
The Spemann-Mangold organizer, also known as the Spemann organizer, is a cluster of cells in the developing embryo of an amphibian that induces development of the central nervous system. Hilde Mangold was a PhD candidate who conducted the organizer experiment in 1921 under the direction of her graduate advisor, Hans Spemann, at the University of Freiburg in Freiburg, German. The discovery of the Spemann-Mangold organizer introduced the concept of induction in embryonic development.
Format: Articles
Subject: Processes
The Boys from Brazil (1978)
The Boys from Brazil is a science fiction film based on the novel of the same name by Ira Levin about an underground neo-Nazi society in South America trying to clone Adolf Hitler, the dictator of Nazi Germany during World War II, to restore the Nazi movement. The film was directed by Franklin Schaffner and released in 1978 by 20th Century Fox in Los Angeles, California. The Boys from Brazil is a film that was one of the first films to depict cloning, and to discuss the ethical implications of genetic engineering, cloning, and eugenics.
Format: Articles
Subject: Publications
Stafford Leak Warren (1896–1981)
Stafford Leak Warren studied nuclear medicine in the United States during the twentieth century. He used radiation to make images of the body for diagnosis or treatment and developed the mammogram, a breast imaging technique that uses low-energy X-rays to produce an image of breasts. Mammograms allow doctors to diagnose breast cancer in its early and most treatable stages.
Format: Articles
Subject: People
Beadle and Tatum's 1941 Experiments with Neurospora Revealed that Genes Produce Enzymes
This illustration shows George Beadle and Edward Tatum's experiments with Neurospora crassa that indicated that single genes produce single enzymes. The pair conducted the experiments at Stanford University in Palo Alto, California. Enzymes are types of proteins that can catalyze reactions inside cells, reactions that produce a number of things, including nutrients that the cell needs. Neurospora crassa is a species of mold that grows on bread.
Format: Graphics
Subject: Theories, Experiments
Amanda Sims Memorial Fund (1930–1935)
In 1930, physician Joseph Colt Bloodgood founded the Amanda Sims Memorial Fund, or the ASMF, a United States cancer awareness organization that focused on spreading information about ways to detect and prevent cervical cancer in women, in Baltimore, Maryland. In partnership with nurse Florence Serpell Deakins Becker, Bloodgood promoted awareness of the early symptoms of cervical cancer among women and advocated for regular pelvic exams. The ASMF partnered with numerous women’s organizations throughout the United States, providing educational information to women of varying backgrounds.
Format: Articles
Subject: Organizations
Meselson, Stahl, and the Replication of DNA: A History of "The Most Beautiful Experiment in Biology" (2001), by Frederic Lawrence Holmes
In 2001, Yale University Press published Frederic Lawrence Holmes' book, Meselson, Stahl, and the Replication of DNA: A History of "The Most Beautiful Experiment in Biology" (Replication of DNA), which chronicles the 1950s debate about how DNA replicates. That experiment verified that DNA replicates semi-conservatively as originally proposed by Watson and Crick. Rather than focusing solely on experiments and findings, Holmes's book presents the investigative processes of scientists studying DNA replication.
Format: Articles
Subject: Publications
Sindell v. Abbott Laboratories (1980)
Sindell v. Abbott Laboratories was a 1980 California case that established the doctrine of market share liability for personal injury cases. For such liability, when a drug causes personal injury and the manufacturer of the drug cannot be identified, each producer is responsible for paying the settlement in proportion to the percentage of the market they supplied. Judith Sindell and Maureen Rogers brought the case against the producers of diethylstilbestrol (DES), which their mothers had taken during pregnancy to prevent miscarriage and other complications.
Format: Articles
Subject: Legal
Betty Friedan (1921–2006)
Betty Friedan advocated for the advancement of women's rights in the twentieth century in the United States. In 1963, Friedan wrote The Feminine Mystique, which historians consider a major contribution to the feminist movement. Friedan also helped establish two organizations that advocated for women's right, the National Organization for Women (NOW) in 1963 and, in 1969 the National Association for the Repeal of Abortion Laws (NAARL). Friedan argued for legalizing access to abortion and contraception, and her advocacy helped advance women's reproductive rights.
Format: Articles
Subject: People
Stephen Jay Gould (1941-2002)
Stephen Jay Gould studied snail fossils and worked at Harvard University in Cambridge, Massachusetts during the latter half of the twentieth century. He contributed to philosophical, historical, and scientific ideas in paleontology, evolutionary theory, and developmental biology. Gould, with Niles Eldredge, proposed the theory of punctuated equilibrium, a view of evolution by which species undergo long periods of stasis followed by rapid changes over relatively short periods instead of continually accumulating slow changes over millions of years.
Format: Articles
Subject: People
Hedgehog Signaling Pathway
The hedgehog signaling pathway is a mechanism that directs the development of embryonic cells in animals, from invertebrates to vertebrates. The hedgehog signaling pathway is a system of genes and gene products, mostly proteins, that convert one kind of signal into another, called transduction. In 1980, Christiane Nusslein-Volhard and Eric F. Wieschaus, at the European Molecular Biology Laboratory in Heidelberg, Germany, identified several fruit fly (Drosophila melanogaster) genes.
Format: Articles
Subject: Processes
Turpin v. Sortini (1982)
The Supreme Court of California reversed the Superior Court of Fresno County's decision to dismiss the Turpins' claims in the case Turpin v. Sortini on 3 May 1982. The case was based upon a wrongful life claim, in which a disabled child sues physicians for neglecting to inform its parents of potential genetic defects, resulting in harm to the child when it is born. The Turpin case determined tha a physician could be liable for failing to inform parents of potential birth defects in the fetus.
Format: Articles
Subject: Legal, Reproduction
Bernard Rimland (1928-2006)
Bernard Rimland studied autism in children in the United States in the second half of the twentieth century. His early research in the 1950s and into the 1960s led him to assert that infantile autism was a neurodevelopmental disorder, or one that is caused by impairments in the growth and development of the brain or central nervous system. Rimland's assertion that infantile autism was a neurodevelopmental disorder contradicted another theory at that time that the condition resulted from emotionally cold parenting.
Format: Articles
Subject: People