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Harald zur Hausen's Experiments on Human Papillomavirus Causing Cervical Cancer (1976–1987)

From 1977 to 1987, Harald zur Hausen led a team of researchers across several institutions in Germany to investigate whether the human papillomavirus (HPV) caused cervical cancer. Zur Hausen's first experiment tested the hypothesis that HPV caused cervical cancer rather than herpes simplex virus type 2 (HSV-2), the then accepted cause. His second and third experiments detailed methods to identify two previously unidentified HPV strains, HPV 16 and HPV 18, in cervical cancer tumor samples. The experiments showed that HPV 16 and 18 DNA were present in cervical tumor samples.

Format: Articles

Subject: Experiments

Calvin Bridges’ Experiments on Nondisjunction as Evidence for the Chromosome Theory of Heredity (1913-1916)

From 1913 to 1916, Calvin Bridges performed experiments that indicated genes are found on chromosomes. His experiments were a part of his doctoral thesis advised by Thomas Hunt Morgan in New York, New York. In his experiments, Bridges studied Drosophila, the common fruit fly, and by doing so showed that a process called nondisjunction caused chromosomes, under some circumstances, to fail to separate when forming sperm and egg cells. Nondisjunction, as described by Bridges, caused sperm or egg cells to contain abnormal amounts of chromosomes.

Format: Articles

Subject: Experiments, Publications

Induced Pluripotent Stem Cell Experiments by Kazutoshi Takahashi and Shinya Yamanaka in 2006 and 2007

In 2006, Kazutoshi Takahashi and Shinya Yamanaka reprogrammed mice fibroblast cells, which can produce only other fibroblast cells, to become pluripotent stem cells, which have the capacity to produce many different types of cells. Takahashi and Yamanaka also experimented with human cell cultures in 2007. Each worked at Kyoto University in Kyoto, Japan. They called the pluripotent stem cells that they produced induced pluripotent stem cells (iPSCs) because they had induced the adult cells, called differentiated cells, to become pluripotent stem cells through genetic manipulation.

Format: Articles

Subject: Experiments

Christian Peeters and Bert Hölldobler's Experiments on Reproduction in Indian Jumping Ants (1991–1994)

Between 1991 and 1994, Christian Peeters and Bert Hölldobler studied the reproductive behaviors of the Indian jumping ant (Harpegnathos saltator), a species native to southern India. They conducted experiments as part of a larger investigation into conflict and reproductive behavior among ants. Peeters and Hölldobler discovered that Indian jumping ant colonies contained both sexually reproductive workers and egg-laying queens. In most other species of ant, the queens are the only sexually reproductive individuals.

Format: Articles

Subject: Experiments

David Wildt's Domestic Cat and Cheetah Experiments (1978-1983)

David Wildt's cheetah (Acinonyx jubatus) research from 1978-1983 became the foundation for the use of embryological techniques in endangered species breeding programs. The cheetah is a member of the cat family (Felidae), which includes thirty-seven species. According to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) all Felidae species are currently threatened or endangered, with the exception of the domestic cat (Felinus catus).

Format: Articles

Subject: Experiments

Sonja Vernes, et al.'s Experiments On the Gene Networks Affected by the Foxp2 Protein (2011)

In 2011, Sonja Vernes and Simon Fisher performed a series of experiments to determine which developmental processes are controlled by the mouse protein Foxp2. Previous research showed that altering the Foxp2 protein changed how neurons grew, so Vernes and Fisher hypothesized that Foxp2 would affect gene networks that involved in the development of neurons, or nerve cells. Their results confirmed that Foxp2 affected the development of gene networks involved in the growth of neurons, as well as networks that are involved in cell specialization and cell communication.

Format: Articles

Subject: Experiments

Christopher Polge and Lionel Edward Aston Rowson’s Experiments on the Freezing of Bull Spermatozoa (1950–1952)

In 1952, researchers Christopher Polge and Lionel Edward Aston Rowson, who worked at the Animal Research Center in Cambridge, England, detailed several experiments on protocols for freezing bull semen for use in the artificial insemination of cows. Freezing sperm extends the life of a viable sperm sample and allows it to be used at later times, such as in artificial insemination. The researchers examined the effects of freezing conditions on bull sperm and how well they produce fertilized embryos once thawed.

Format: Articles

Subject: Experiments

Jeffrey Weinzweig's Experiments on In Utero Cleft Palate Repair in Goats (1999-2002)

Jeffrey Weinzweig and his team, in the US at the turn of the twenty-first century, performed a series of experiments on fetal goats to study the feasibility of repairing cleft palates on organisms still in the womb. Weinzweig , a plastic surgeon who specialized in cleft palate repair, and his team developed a method to cause cleft palates in fetal goats that are similar to clefts that occur in human fetuses. Using their goat congenital model, the team developed a method to repair a congenital cleft palate in utero, or in the womb.

Format: Articles

Subject: Experiments, Disorders

Jennifer Doudna and Emmanuelle Charpentier’s Experiment About the CRISPR/cas 9 System’s Role in Adaptive Bacterial Immunity (2012)

In 2012, Jennifer Doudna, Emmanuelle Charpentier from the University of California, Berkeley, in Berkeley, California, and Umeå University in Umeå, Sweden, along with their colleagues discovered how bacteria use the CRISPR/cas 9 system to protect themselves from viruses. The researchers also proposed the idea of using the CRISPR/cas 9 system as a genome editing tool.

Format: Articles

Subject: Experiments

Hox Genes and the Evolution of Vertebrate Axial Morphology Experiment (1995)

In 1995, researchers Ann Burke, Craig Nelson, Bruce Morgan, and Cliff Tabin in the US studied the genes that regulate the construction of vertebra in developing chick and mouse embryos, they showed similar patterns of gene regulation across both species, and they concluded that those patterns were inherited from an ancestor common to all vertebrate animals. The group analyzed the head-to-tail (anterior-posterior) axial development of vertebrates, as the anterior-posterior axis showed variation between species over the course of evolutionary time.

Format: Articles

Subject: Experiments

"Genetic Control of Biochemical Reactions in Neurospora" (1941), by George W. Beadle and Edward L. Tatum

George Wells Beadle and Edward Lawrie Tatum's 1941 article Genetic Control of Biochemical Reactions in Neurospora detailed their experiments on how genes regulated chemical reactions, and how the chemical reactions in turn affected development in the organism. Beadle and Tatum experimented on Neurospora, a type of bread mold, and they concluded that mutations to genes affected the enzymes of organisms, a result that biologists later generalized to proteins, not just enzymes.

Format: Articles

Subject: Experiments

Experiments on the Reproductive Costs of a Pure Capital Breeder, the Children’s Python (Antaresia childreni) (2013), by Olivier Lourdais, Sophie Lorioux, and Dale F. DeNardo

In 2013, Olivier Lourdais, Sophie Lorioux, and Dale DeNardo conducted a study on the impact of the reproductive effort on the muscle size and the constriction strength of female Children’s pythons. Children’s pythons are pure capital breeders, meaning that they do not eat during vitellogenesis, a process in which egg-laying or oviparous species allocate bodily resources including fat, water, and protein to follicles in the ovary that develop into eggs.

Format: Articles

Subject: Experiments

"The Developmental Capacity of Nuclei Taken from Intestinal Epithelium Cells of Feeding Tadpoles" (1962), by John B. Gurdon

In 1962 researcher John Bertrand Gurdon at the University of Oxford in Oxford, England, conducted a series of experiments on the developmental capacity of nuclei taken from intestinal epithelium cells of feeding tadpoles. In the experiments, Gurdon conducted nuclear transplantation, or cloning, of differentiated cells, or cells that have already specialized to become one cell type or another, in tadpoles. Gurdon's experiment showed that differentiated adult cells could be induced to an undifferentiated state, where they could once again become multiple cell types.

Format: Articles

Subject: Experiments

Hermann Joseph Muller's Study of X-rays as a Mutagen, (1926-1927)

Hermann Joseph Muller conducted three experiments in 1926 and 1927 that demonstrated that exposure to x-rays, a form of high-energy radiation, can cause genetic mutations, changes to an organism's genome, particularly in egg and sperm cells. In his experiments, Muller exposed fruit flies (Drosophila) to x-rays, mated the flies, and observed the number of mutations in the offspring. In 1927, Muller described the results of his experiments in "Artificial Transmutation of the Gene" and "The Problem of Genic Modification".

Format: Articles

Subject: Experiments

"Control of Corneal Differentiation by Extracellular Materials" (1974), by Stephen Meier and Elizabeth D. Hay

In 1974, Elizabeth Dexter Hay and Stephen Meier in the US conducted an experiment that demonstrated that the extracellular matrix, the mesh-like network of proteins and carbohydrates found outside of cells in the body, interacted with cells and affected their behaviors. In the experiment, Hay and Meier removed the outermost layer of cells that line the front of the eye, called corneal epithelium, from developing chick embryos.

Format: Articles

Subject: Experiments

HIP Randomized Breast Cancer Screening Trial (1963–1982)

From 1963 to 1982, researchers in New York City, New York, carried out a randomized trial of mammography screening. Mammography is the use of X-ray technology to find breast cancer at early stages. The private insurance company Health Insurance Plan of Greater New York, or HIP, collaborated with researchers Sam Shapiro, Philip Strax, and Louis Venet on the trial. The researchers’ goal was to determine whether mammography screening reduced breast cancer mortality in women. The study included sixty thousand women aged forty to sixty-four.

Format: Articles

Subject: Experiments

"On the Nature of the Process of Fertilization and the Artificial Production of Normal Larvae (Plutei) From the Unfertilized Eggs of the Sea Urchin" (1899), by Jacques Loeb

Jacques Loeb developed procedures to make embryos from unfertilized sea urchin eggs in 1899. Loeb called the procedures "artificial parthenogenesis," and he introduced them and his results in "On the Nature of the Process of Fertilization and the Artificial Production of Norma Larvae (Plutei) from the Unfertilized Eggs of the Sea Urchin" in an 1899 issue of The American Journal of Physiology. In 1900 Loeb elaborated on his experiments.

Format: Articles

Subject: Experiments

"Transplantation of Living Nuclei from Blastula Cells into Enucleated Frogs' Eggs" (1952), by Robert Briggs and Thomas J. King

In 1952 Robert Briggs and Thomas J. King published their article, "Transplantation of Living Nuclei from Blastula Cells into Enucleated Frogs' Eggs," in the Proceedings of the National Academy of Sciences, the culmination of a series of experiments conducted at the Institute for Cancer Research and Lankenau Hospital Research Institute in Philadelphia, Pennsylvania. In this paper Briggs and King examined whether nuclei of embryonic cells are differentiated, and by doing so, were the first to conduct a successful nuclear transplantation with amphibian embryos.

Format: Articles

Subject: Experiments

"The Limited In Vitro Lifetime of Human Diploid Cell Strains" (1964), by Leonard Hayflick

Leonard Hayflick in the US during the early 1960s showed that normal populations of embryonic cells divide a finite number of times. He published his results as 'The Limited In Vitro Lifetime of Human Diploid Cell Strains' in 1964. Hayflick performed the experiment with WI-38 fetal lung cells, named after the Wistar Institute, in Philadelphia, Pennsylvania, where Hayflick worked. Frank MacFarlane Burnet, later called the limit in capacity for cellular division the Hayflick Limit in 1974.

Format: Articles

Subject: Experiments

"Sheep Cloned by Nuclear Transfer from a Cultured Cell Line" (1996), by Keith Campbell, Jim McWhir, William Ritchie, and Ian Wilmut

In 1995 and 1996, researchers at the Roslin Institute in Edinburgh, Scotland, cloned mammals for the first time. Keith Campbell, Jim McWhir, William Ritchie, and Ian Wilmut cloned two sheep, Megan and Morag, using sheep embryo cells. The experiments indicated how to reprogram nuclei from differentiated cells to produce live offspring, and that a single population of differentiated cells could produce multiple offspring. They reported their results in the article 'Sheep Cloned by Nuclear Transfer from a Cultured Cell Line' in March 1996.

Format: Articles

Subject: Experiments

Experimental Studies on Germinal Localization (1904), by Edmund B. Wilson

At the turn of the twentieth century, Edmund B. Wilson
performed experiments to show where germinal
matter was located in molluscs. At Columbia University in New York City,
New York, Wilson studied what causes cells to differentiate during
development. In 1904 he conducted his experiments on molluscs, and he modified the
theory about the location of germinal matter in the succeeding years. Wilson and others modified the
theory of germinal localization to accommodate results that showed

Format: Articles

Subject: Experiments

"Viable Offspring Derived from Fetal and Adult Mammalian Cells" (1997), by Ian Wilmut et al.

In the 1990s, Ian Wilmut, Jim McWhir, and Keith Campbell performed experiments while working at the Roslin Institute in Roslin, Scotland. Wilmut, McWhir, and Campbell collaborated with Angelica Schnieke and Alex J. Kind at PPL Therapeutics in Roslin, a company researching cloning and genetic manipulation for livestock. Their experiments resulted in several sheep being born in July 1996, one of which was a sheep named Dolly born 5 July 1996.

Format: Articles

Subject: Experiments

"Versuche zur Analyse der Induktionsmittel in der Embryonalentwicklung" (1932), by Hermann Bautzmann, Johannes Holtfreter, Otto Mangold, and Hans Spemann

In "Versuche zur Analyse der Induktionsmittel in der Embryonalentwicklung," published in Naturwissenschaften in 1932, Hermann Bautzmann, Johannes Holtfreter, Otto Mangold, and Hans Spemann jointly reported on experiments each had conducted testing the activity of organizers killed by boiling, freezing, alcohol, and drying. Each of the authors had been independently conducting similar experiments, when Holtfreter made a breakthrough allowing him to produce many more successful transplantations.

Format: Articles

Subject: Experiments

Action of MER-25 and of Clomiphene on the Human Ovary (1963)

Between 1958 and 1962, physicians Olive W. Smith, George V. Smith, and Robert W. Kistner performed experiments that demonstrated the effects of the drugs MER-25 and clomiphene citrate on the female human body. MER-25 and clomiphene citrate are drugs that affect estrogen production in women. At the time of the experiment, researchers did not know which organ or organs the drugs affected, the ovaries and/or the anterior pituitary gland.

Format: Articles

Subject: Experiments

Edgar Allen and Edward A. Doisy's Extraction of Estrogen from Ovarian Follicles, (1923)

In the early 1920s, researchers Edgar Allen and Edward Adelbert Doisy conducted an experiment that demonstrated that ovarian follicles, which produce eggs in mammals, also contain and produce what they called the primary ovarian hormone, later renamed estrogen. In their experiment, Doisy and Allen extracted estrogen from the ovarian follicles of hogs and proved that they had isolated estrogen by using a measurement later renamed the Allen-Doisy test.

Format: Articles

Subject: Experiments