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Mitochondria

All cells that have a nucleus, including plant, animal, fungal cells, and most single-celled protists, also have mitochondria. Mitochondria are particles called organelles found outside the nucleus in a cell's cytoplasm. The main function of mitochondria is to supply energy to the cell, and therefore to the organism. The theory for how mitochondria evolved, proposed by Lynn Margulis in the twentieth century, is that they were once free-living organisms.

Format: Articles

Subject: Organisms, Theories

Shinya Yamanaka (1962- )

Shinya Yamanaka gained international prominence after publishing articles detailing the successful generation of induced pluripotent stem (iPS) cells, first in mice, then in humans. Yamanaka induced somatic cells to act like human embryonic stem cells (hESCs), allowing researchers to experiment with non-embryonic stem cells with a similar capacity as hESCs. The research involving iPS cells therefore offered new potential for research and application in medical treatment, without many of the ethical objections that hESC research entailed.

Format: Articles

Subject: People

Wolbachia

Bacteria of the genus Wolbachia are
bacteria that live within the cells of their hosts. They infect a
wide range of arthropods (insects, arachnids, and crustaceans) and
some nematodes (parasitic roundworms). Scientists estimate that
Wolbachia exist in between seventeen percent and seventy-six percent of
arthropods and nematodes. The frequency of the bacteria makes them
one of the most widespread parasites. In general, they are divided
into five groups, from A to E, depending of the species of their

Format: Articles

Subject: Organisms

David Reimer and John Money Gender Reassignment Controversy: The John/Joan Case

In the mid-1960s, psychologist John Money encouraged the gender reassignment of David Reimer, who was born a biological male but suffered irreparable damage to his penis as an infant. Born in 1965 as Bruce Reimer, his penis was irreparably damaged during infancy due to a failed circumcision. After encouragement from Money, Reimer’s parents decided to raise Reimer as a girl. Reimer underwent surgery as an infant to construct rudimentary female genitals, and was given female hormones during puberty.

Format: Articles

Subject: Theories

George Wells Beadle (1903-1989)

George Wells Beadle studied corn, fruit flies, and funguses in the US during the twentieth century. These studies helped Beadle earn the 1958 Nobel Prize in Physiology or Medicine. Beadle shared the prize with Edward Tatum for their discovery that genes help regulate chemical processes in and between cells. This finding, initially termed the one gene-one enzyme hypothesis, helped scientists develop new techniques to study genes and DNA as molecules, not just as units of heredity between generations of organisms.

Format: Articles

Subject: People

Jacques Loeb (1859-1924)

Jacques Loeb experimented on embryos in Europe and the United States at the end of the nineteenth and beginning of the twentieth centuries. Among the first to study embryos through experimentation, Loeb helped found the new field of experimental embryology. Notably, Loeb showed scientists how to create artificial parthenogenesis, thus refuting the idea that spermatozoa alone were necessary to develop eggs into embryos and confirming the idea that the chemical constitution of embryos environment affected their development.

Format: Articles

Subject: People

Torsten Wiesel (1924– )

Torsten Nils Wiesel studied visual information processing and development in the US during the twentieth century. He performed multiple experiments on cats in which he sewed one of their eyes shut and monitored the response of the cat’s visual system after opening the sutured eye. For his work on visual processing, Wiesel received the Nobel Prize in Physiology or Medicine in 1981 along with David Hubel and Roger Sperry.

Format: Articles

Subject: People

Edwin Stephen Goodrich (1868-1946)

Edwin Stephen Goodrich studied the structures of animals in England during the nineteenth and twentieth centuries. Goodrich studied how animals develop to identify their parts and to establish the evolutionary relationships between different species. Goodrich established that body structures can shift their positions relative to an organism's body during evolution, and he hypothesized that body structures can share ancestry (homology) between organisms of different species, even without identical body placement.

Format: Articles

Subject: People

Johann Gregor Mendel (1822-1884)

Johann Gregor Mendel studied plants and their patterns of inheritance in Austria during the nineteenth century. Mendel experimented with the pea plant, Pisum, and his publication, 'Versuche uber Pflanzenhybriden' (“Experiments on Plant Hybridization”), published in 1866, revolutionized theories of trait inheritance. Mendel’s discoveries relating to factors, traits, and how they pass between generations of organisms enabled scientists in the twentieth century to build theories of genetics.

Format: Articles

Subject: People

Hamlin Fistula Ethiopia (1974- )

Hamlin Fistula Ethiopia is a nonprofit organization that began in 1974 as a joint endeavor by Reginald and Catherine Hamlin and the Addis Ababa Fistula Hospital in Addis Ababa, Ethiopia. Hamlin Fistula Ethiopia promotes reproductive health in Ethiopia by raising awareness and implementing treatment and preventive services for women affected by obstetric fistulas. It also aims to restore the lives of women afflicted with obstetric fistulas in Ethiopia and eventually to eradicate the condition.

Format: Articles

Subject: Organizations, Reproduction, Outreach

James David Ebert (1921-2001)

James David Ebert studied the developmental processes of chicks and of viruses in the US during the twentieth century. He also helped build and grow many research institutions, such as the Department of Embryology in the Carnegie Institution of Washington in Baltimore, Maryland and the Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts. When few biologists studied the biochemistry of embryos, Ebert built programs and courses around the foci of biochemistry and genetics, especially with regards to embryology.

Format: Articles

Subject: People

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

The Marine Biological Laboratory Embryology Course

The Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts, began in 1888 to offer opportunities for instruction and research in biological topics. For the first few years, this meant that individual investigators had a small lab space upstairs in the one wooden building on campus where students heard their lectures and did their research in a common area downstairs.

Format: Articles

Subject: Organizations

Evans v. People of the State of New York [Brief] (1872)

Attempts by the New York legislature to make abortion a crime regardless of the stage of gestation were permanently frustrated because the court decided that manslaughter cannot occur until the law recognizes a living being in gestation and that only happens after quickening.

Format: Articles

Subject: Legal, Reproduction

Julia Clifford Lathrop (1858–1932)

Julia Clifford Lathrop was an activist and social reformer in the late nineteenth to early twentieth centuries and the first chief of the United States Children’s Bureau. In that capacity, she conducted demographic studies to identify links between socioeconomic factors and infant mortality rates. Lathrop mobilized the effort to increase birth registration and designed programs and publications to promote infant and maternal health throughout the US.

Format: Articles

Subject: People, Outreach

In the Womb: Identical Twins (2009), by National Geographic

National Geographic's documentary In the Womb: Identical Twins focuses on the prenatal development of human identical twins. Director Lorne Townend uses three-dimensional (3D) and four-dimensional (4D) ultrasound imaging and microscopy to depict twin development , genetic and epigenetic variations in the fetuses, and methods of fetal survival in the confines of the womb. Artist renditions of scientific data fill in areas of development inaccessible to the imaging tools.

Format: Articles

Subject: Outreach, Reproduction

Matthias Jacob Schleiden (1804–1881)

Matthias Jacob Schleiden helped develop the cell theory in Germany during the nineteenth century. Schleiden studied cells as the common element among all plants and animals. Schleiden contributed to the field of embryology through his introduction of the Zeiss microscope lens and via his work with cells and cell theory as an organizing principle of biology.

Format: Articles

Subject: People

Pfeffer Cell Apparatus

The Pfeffer Zelle (Pfeffer Cell Apparatus), invented by Wilhelm Pfeffer in 1877, measured the minimum pressure needed to prevent a pure solvent from passing into a solution across a semi-permeable membrane, called osmotic pressure. The apparatus provided Pfeffer with a way to quantitatively measure osmotic pressure. Pfeffer devised the apparatus in the 1870s at the University of Basel in Basel, Switzerland, and he described the Pfeffer Cell Apparatus in his 1877 book Osmotische Untersuchungen: Studien Zur Zellmechanik (Osmotic Investigations: Studies on Cell Mechanics).

Format: Articles

Subject: Technologies

Inducing Fertilization and Development in Sand Dollars

Sand dollars are common marine invertebrates in the phylum Echinodermata and share the same class (Echinoidea) as sea urchins. They have served as model laboratory organisms for such embryologists as Frank Rattray Lillie and Ernest Everett Just. Both Lillie and Just used Echinarachnius parma for their studies of egg cell membranes and embryo development at the Marine Biological Laboratory (MBL) at Woods Hole, Massachusetts, in the early 1900s.

Format: Articles

Subject: Processes

Simon Edward Fisher (1970-)

Simon Edward Fisher studied the genes that control speech and language in England and the Netherlands in the late twentieth and early twenty-first centuries. In 2001, Fisher co-discovered the FOXP2 gene with Cecilia Lai, a gene related to language acquisition in humans and vocalization in other mammals. When damaged, the human version of the gene leads to language disorders that disrupt language and speech skills. Fisher's discovery validated the hypothesis that genes influence language, resulting in further investigations of language disorders and their heritability.

Format: Articles

Subject: People

Marshall Henry Klaus (1927–2017)

Marshall Henry Klaus was a scientist and pediatrician who studied maternal-infant bonding in the twentieth century in the United States. Maternal-infant bonding is the psychological and chemical attachment between mother and infant. Klaus cofounded DONA International, an organization that trains birthing aides, called doulas, to provide physical and emotional support to laboring mothers. He also studied the differences between the layouts and quality of care provided in nurseries and birthing centers in different countries and compared them to those found in the United States.

Format: Articles

Subject: People

“A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation” (1993), by Dean H. Hamer and Charles A. Thomas.

In 1993, Dean H. Hamer and colleagues in the US published results from their research that indicated that men with speicifc genes were more likely to be homosexual than were men without those genes. The study hypothesized that some X chromosomes contain a gene, Xq28, that increases the likelihood of an individual to be homosexual. Prior to those results, researchers had argued that the cause of homosexuality was environmental and that homosexuality could be altered or reversed. Hamer’s research suggested a possible genetic cause of homosexuality.

Format: Articles

Subject: Experiments

"Congenital Club Foot in the Human Fetus" (1980), by Ernesto Ippolito and Ignacio Ponseti

In 1980, Ernesto Ippolito and Ignacio Ponseti published their results on a histological study they performed on congenital club foot in human fetuses. The researchers examined the feet of four aborted fetuses and compared the skeletal tissues from healthy feet to those affected by congenital club foot. Infants born with club foot are born with one or both feet rigidly twisted inwards and upwards, making typical movement painful and challenging.

Format: Articles

Subject: Experiments

“Traditional postpartum practices and rituals: a qualitative systematic review” (2007), by Cindy-Lee Dennis, Kenneth Fung, Sophie Grigoriadis, Gail Erlick Robinson, Sarah Romans and Lori Ross

In the 2007 paper “Traditional postpartum practices and rituals: a qualitative systematic review,” Toronto-based researchers showed that women from different cultures around the world follow similar postpartum practices after giving birth. At the University of Toronto in Toronto, Canada, Cindy-Lee Dennis, Kenneth Fung, Sophie Grigoriadis, Gail Erlick Robinson, Sarah Romans, and Lori Ross examined fifty-one studies from over twenty countries that focused on traditional postpartum practices.

Format: Articles

Subject: Publications

Ernst Haeckel's Biogenetic Law (1866)

The biogenetic law is a theory of development and evolution proposed by Ernst Haeckel in Germany in the 1860s. It is one of several recapitulation theories, which posit that the stages of development for an animal embryo are the same as other animals' adult stages or forms. Commonly stated as ontogeny recapitulates phylogeny, the biogenetic law theorizes that the stages an animal embryo undergoes during development are a chronological replay of that species' past evolutionary forms.

Format: Articles

Subject: Theories