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Wilhelm Ludvig Johannsen (1857-1927)

Wilhelm Ludvig Johannsen studied plants and helped found the field of genetics, contributing methods and concepts to the study of heredity around the turn of the twentieth century in Denmark. His experiments on heredity and variation in plants influenced the methods and techniques of geneticists, and his distinction between the genotype of an organism-its hereditary disposition-and its phenotype-its observable characteristics-remains at the core of contemporary biology. Johannsen criticized biological explanations that relied on concepts such as vitalism and teleology.

Format: Articles

Subject: People

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

Roger Wolcott Sperry (1913–1994)

Roger Wolcott Sperry
studied the function of the nervous system in the US during the
twentieth century. He studied split-brain patterns in cats and
humans that result from separating the two hemispheres of the
brain by cutting the corpus callosum, the bridge between the two
hemispheres of the brain. He found that separating the corpus
callosum the two hemispheres of the brain could not communicate
and they performed functions as if the other hemisphere did not

Format: Articles

Subject: People

Harry Hamilton Laughlin (1880-1943)

Harry Hamilton Laughlin helped lead the eugenics
movement in the United States during the early twentieth century.
The US eugenics movement of the early twentieth century sought to
reform the genetic composition of the United States population through
sterilization and other restrictive reproductive measures. Laughlin
worked as superintendent and assistant director of the Eugenics
Research Office (ERO) at Cold Spring Harbor Laboratory in Cold
Spring Harbor, New York, alongside director Charles Davenport.

Format: Articles

Subject: People, Reproduction

Edward Charles Dodds (1899-1973)

Edward Charles Dodds researched the function and effects of natural and artificial hormones on the endocrine system in England during the twentieth century. Though he first worked with hormones such as insulin, Dodds focused on the effects of estrogen in the body and how to replicate those effects with artificial substances. In 1938, along with chemist Robert Robinson, Dodds synthesized the first synthetic estrogen called diethylstilbestrol.

Format: Articles

Subject: People

Nicole Marthe Le Douarin (1930- )

Nicole Marthe Le Douarin was one of the first progressive female pioneers of developmental and embryological research. Some of her most notable and ground-breaking work involves grafting quail and chicken embryos together in order to study the developmental fate of each contributing embryo. Le Douarin was born in Brittany, France, on 20 August 1930. As an only child she was inspired by her mother, a school teacher at the time, to develop a passion for learning.

Format: Articles

Subject: People

Abraham Trembley (1710-1784)

Abraham Trembley's discovery of the remarkable regenerative capacity of the hydra caused many to question their beliefs about the generation of organisms. Born 3 September 1710 to a prominent Geneva family, Trembley studied at the Calvin Institute, now the University of Geneva, where he completed his thesis on calculus. He went on to become tutor for Count William Bentinck's two sons, and it was while teaching the boys natural history that Trembley came across a strange organism in a sample of pond water.

Format: Articles

Subject: People

Adib Jatene (1929–2014)

Adib Jatene in Brazil was the first surgeon to successfully perform the arterial switch operation in 1975. The operation corrected a heart condition in infants called transposition of the great arteries (TGA). Left untreated, infants with TGA die, as their blood cannot supply oxygen to their bodies. Jatene’s operation became widely used to correct the condition. Aside from medical research, Jatene worked for years in politics and education, serving as Brazil’s minister of health and teaching thoracic surgery at the University of São Paulo.

Format: Articles

Subject: People

David Starr Jordan (1851-1931)

David Starr Jordan studied fish and promoted eugenics in the US during the late nineteenth and early twentieth centuries. In his work, he embraced Charles Darwin s theory of evolution and described the importance of embryology in tracing phylogenic relationships. In 1891, he became the president of Stanford University in Stanford, California. Jordan condemned war and promoted conservationist causes for the California wilderness, and he advocated for the eugenic sterilization of thousands of Americans.

Format: Articles

Subject: People, Reproduction

Lynn Petra Alexander Sagan Margulis (1938-2011)

Lynn Petra Alexander Sagan Margulis was an American biologist, whose work in the mid-twentieth century focused on cells living together in a mutually advantageous relationship, studied cells and mitochondria in the US during the second half of the twentieth century. She developed a theory for the origin of eukaryotic cells, that proposed two kinds of structures found in eukaryotic cells mitochondria in animals, and plastids in plantsÑwere once free-living bacteria that lived harmoniously and in close proximity to larger cells, a scenario called symbiosis.

Format: Articles

Subject: People, Theories

Walter Jakob Gehring (1939-2014)

Walter Jakob Gehring discovered the homeobox, a DNA segment found in a specific cluster of genes that determine the body plan of animals, plants, and fungi. Gehring identified the homeobox in 1983, with the help of colleagues while isolating the Antennapedia (Antp) gene in fruit flies (Drosophila) at the University of Basel in Basel, Switzerland. Hox genes, a family of genes that have the homeobox, determine the head-to-tail (anterior-posterior) body axis of both vertebrates and invertebrates.

Format: Articles

Subject: People

Jan Evangelista Purkyne (1787-1869)

Jan Evangelista Purkyne, also called Johannes or Johann Evangelist Purkinje, studied cells in the cerebellum, fibers of the heart, subjective visual phenomenon, and germinal vesicle, in eastern Europe during the early nineteenth century. His investigations provided insights into various mechanisms and structures of the human body. Purkyne introduced techniques for decalcification of bones and teeth, embedding of tissue specimens, and eye examinations.

Format: Articles

Subject: People

Keith Henry Stockman Campbell (1954-2012)

Keith Henry Stockman Campbell studied embryo growth and cell differentiation during the twentieth and twenty-first centuries in the UK. In 1995, Campbell and his scientific team used cells grown and differentiated in a laboratory to clone sheep for the first time. They named these two sheep Megan and Morag. Campbell and his team also cloned a sheep from adult cells in 1996, which they named Dolly. Dolly was the first mammal cloned from specialized adult (somatic) cells with the technique of somatic cell nuclear transfer (SCNT).

Format: Articles

Subject: People

Austin Bradford Hill (1897-1991)

During the twentieth century, Austin Bradford Hill researched diseases and their causes in England and developed the Bradford Hill criteria, which comprise the minimal requirements that must be met for a causal relationship to be established between a factor and a disease. Hill also suggested that researchers should randomize clinical trials to evaluate the effects of a drug or treatment by monitoring large groups of people.

Format: Articles

Subject: People

James William Kitching (1922-2003)

James William Kitching collected and studied fossils of dinosaurs and early humans in the twentieth century. He worked at the Bernard Price Institute for Paleontological Research in South Africa. During the fifty-three years he worked at the institute, Kitching spent eighteen of those in the field uncovering fossils. Kitching recovered fossils of early human ancestors, later called Australopithecines, as well as fossils of dinosaurs and ancient mammals. When he died in 2003, the Bernard Price Institute housed one of the largest fossil collections in the southern hemisphere.

Format: Articles

Subject: People

Albert William Liley (1929–1983)

Albert William Liley advanced the science of fetal physiology and the techniques of life-saving in utero blood transfusions for fetuses with Rh incompatibility, also known as hemolytic disease. Due to his advances, fetuses too young to survive premature delivery, and likely to die in utero if their Rh incompabilities were left untreated, were successfully transfused and carried to term. Liley was as passionate as a clinician and researcher as he was about his views on the rights of the unborn.

Format: Articles

Subject: People, Reproduction

St. George Jackson Mivart (1827-1900)

St. George Jackson Mivart studied animals and worked in England during the nineteenth century. He also proposed a theory of organismal development that he called individuation, and he critiqued Charles Darwin's argument for evolution by natural selection. His work on prosimians, a group of primates excluding apes and monkeys, helped scientists better investigate the Primate group.

Format: Articles

Subject: People

Max Ludwig Henning Delbruck (1906–1981)

Max Ludwig Henning Delbrick applied his knowledge of theoretical physics to biological systems such as bacterial viruses called bacteriophages, or phages, and gene replication during the twentieth century in Germany and the US. Delbrück demonstrated that bacteria undergo random genetic mutations to resist phage infections. Those findings linked bacterial genetics to the genetics of higher organisms. In the mid-twentieth century, Delbrück helped start the Phage Group and Phage Course in the US, which further organized phage research.

Format: Articles

Subject: People

John Charles Rock (1890-1984)

Born on 24 March 1890 in Marlborough, Massachusetts, to Ann and Frank Rock, John Charles Rock was both a devout Catholic and one of the leading investigators involved in the development of the first oral contraceptive pill. In 1925 he married Anna Thorndike, with whom he later had five children. He spent over thirty years of his career as a clinical professor of obstetrics at Harvard Medical School, and in 1964 the Center for Population Studies of the Harvard School of Public Health established the John Rock Professorship.

Format: Articles

Subject: People, Reproduction

HeLa Cell Line

The HeLa cell line was the first immortal human cell line that George Otto Gey, Margaret Gey, and Mary Kucibek first isolated from Henrietta Lacks and developed at The Johns Hopkins Hospital in Baltimore, Maryland, in 1951. An immortal human cell line is a cluster of cells that continuously multiply on their own outside of the human from which they originated. Scientists use immortal human cell lines in their research to investigate how cells function in humans.

Format: Articles

Subject: Technologies, Experiments, People, Ethics

George McDonald Church (1954- )

George McDonald Church studied DNA from living and from extinct species in the US during the twentieth and twenty-first centuries. Church helped to develop and refine techniques with which to describe the complete sequence of all the DNA nucleotides in an organism's genome, techniques such as multiplex sequencing, polony sequencing, and nanopore sequencing. Church also contributed to the Human Genome Project, and in 2005 he helped start a company, the Personal Genome Project. Church proposed to use DNA from extinct species to clone and breed new organisms from those species.

Format: Articles

Subject: People, Technologies

William Withey Gull (1816-1890)

William Withey Gull studied paraplegia, anorexia, and hormones as a physician in England during the nineteenth century. In addition to caring for patients, he described the role of the posterior column of the spinal cord in paraplegia, and he was among the first to describe the conditions of anorexia and of hypochondria. He also researched the effects of thyroid hormone deficiencies in women who had malfunctioning thyroid glands.

Format: Articles

Subject: People

Peter Mazur (1928–2015)

Peter Mazur was a researcher in the US who developed new ways of preserving biological material by freezing it, a process called cryopreservation. If done correctly, cryopreservation enables scientists to store or study biological material for an extended period of time. If done incorrectly, cryopreservation can easily harm or destroy biological material. Mazur worked to find the best ways to cryopreserve different cells, embryos, and organs in order to minimize the damage caused by freezing.

Format: Articles

Subject: People

Aristotle (384-322 BCE)

Aristotle studied developing organisms, among other things, in ancient Greece, and his writings shaped Western philosophy and natural science for greater than two thousand years. He spent much of his life in Greece and studied with Plato at Plato's Academy in Athens, where he later established his own school called the Lyceum. Aristotle wrote greater than 150 treatises on subjects ranging from aesthetics, politics, ethics, and natural philosophy, which include physics and biology. Less than fifty of Aristotle's treatises persisted into the twenty-first century.

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