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Essay: Homology

Homology is a central concept of comparative and evolutionary biology, referring to the presence of the same bodily parts (e.g., morphological structures) in different species. The existence of homologies is explained by common ancestry, and according to modern definitions of homology, two structures in different species are homologous if they are derived from the same structure in the common ancestor.

Format: Essays and Theses

Subject: Processes

“Maternal and Perinatal Outcomes Associated with a Trial of Labor after Prior Cesarean Delivery” (2004), Mark B. Landon et al.

In 2004 Mark Landon and his colleagues in the United States published “Maternal and Perinatal Outcomes Associated with a Trial of Labor after Prior Cesarean Delivery,” which compared the risks of vaginal delivery and cesarean section for delivery of a fetus after a previous cesarean delivery. During a cesarean section, a physician surgically removes a fetus from a pregnant woman through an incision in her abdomen. By the late 1900s, most clinical guidelines viewed attempting a vaginal birth after a previous cesarean delivery as a reasonable option for most women.

Format: Articles

Subject: Publications

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

The Sex Education of Children: A Book for Parents (1931), by Mary Ware Dennett

Mary Coffin Ware Dennett, a supporter of sex education for children in the US in the early twentieth century, wrote The Sex Education of Children: A Book for Parents as a resource for parents teaching their children about sex. Vanguard Press in New York City, New York, published The Sex Education of Children in 1931. Dennett’s book addresses issues that Dennett argued parents should know about sex to provide their children with an accurate portrayal of the topic.

Format: Articles

Subject: Publications

Mitochondrial Diseases in Humans

Mitochondrial diseases in humans result when the small organelles called mitochondria, which exist in all human cells, fail to function normally. The mitochondria contain their own mitochondrial DNA (mtDNA) separate from the cell's nuclear DNA (nDNA). The main function of mitochondria is to produce energy for the cell. They also function in a diverse set of mechanisms such as calcium hemostasis, cell signaling, regulation of programmed cell death (apoptosis), and biosynthesis of heme proteins that carry oxygen.

Format: Articles

Subject: Disorders, Reproduction

On the Generation of Animals, by Aristotle

Aristotle's On the Generation of Animals is referred to in Latin as De Generatione animalium. As with many of Aristotle's writings, the exact date of authorship is unknown, but it was produced in the latter part of the fourth century B.C. This book is the second recorded work on embryology that is treated as a subject of philosophy, being preceded by contributions in the Hippocratic corpus by about a century.

Format: Articles

Subject: Publications

"Gene Regulation for Higher Cells: A Theory" (1969), by Roy J. Britten and Eric H. Davidson

In 1969, Roy J. Britten and Eric H. Davidson published Gene Regulation for Higher Cells: A Theory, in Science. A Theory proposes a minimal model of gene regulation, in which various types of genes interact to control the differentiation of cells through differential gene expression. Britten worked at the Carnegie Institute of Washington in Washington, D.C., while Davidson worked at the California Institute of Technology in Pasadena, California. Their paper was an early theoretical and mechanistic description of gene regulation in higher organisms.

Format: Articles

Subject: Publications

The First Successful Cloning of a Gaur (2000), by Advanced Cell Technology

Advanced Cell Technology (ACT), a stem cell biotechnology company in Worcester, Massachusetts, showed the potential for cloning to contribute to conservation efforts. In 2000 ACT researchers in the United States cloned a gaur (Bos gaurus), an Asian ox with a then declining wild population. The researchers used cryopreserved gaur skin cells combined with an embryo of a domestic cow (Bos taurus). A domestic cow also served as the surrogate for the developing gaur clone.

Format: Articles

Subject: Experiments

"The Role of Maternal Mitochondria during Oogenesis, Fertilization and Embryogenesis" (2002), by James M. Cummins

James M Cummins published 'The Role of Maternal Mitochondria during Oogenesis, Fertilization and Embryogenesis' 30 January 2002 in Reproductive BioMedicine Online. In the article, Cummins examines the role of the energy producing cytoplasmic particles, or organelles called mitochondria. Humans inherit mitochondria from their mothers, and mechanisms have evolved to eliminate sperm mitochondria in early embryonic development. Mitochondria contain their own DNA (mtDNA) separate from nuclear DNA (nDNA).

Format: Articles

Subject: Publications

Johann Friedrich Blumenbach (1752-1840)

In eighteenth century Germany, Johann Friedrich Blumenbach studied how individuals within a species vary, and to explain such variations, he proposed that a force operates on organisms as they develop. Blumenbach used metrical methods to study the history of humans, but he was also a natural historian and theorist. Blumenbach argued for theories of the transformation of species, or the claim that new species can develop from existing forms.

Format: Articles

Subject: People

Life's Greatest Miracle (2001), by Julia Cort and NOVA

The Public Broadcasting Station (PBS) documentary Life's Greatest Miracle (abbreviated Miracle, available at http://www.pbs.org/wgbh/nova/miracle/program.html), is arguably one of the most vivid illustrations of the making of new human life. Presented as part of the PBS television series NOVA, Miracle is a little less than an hour long and was first aired 20 November 2001. The program was written and produced by Julia Cort and features images by renowned Swedish photographer Lennart Nilsson.

Format: Articles

Subject: Outreach, Reproduction

August Friedrich Leopold Weismann (1834-1914)

August Friedrich Leopold Weismann studied how the traits of organisms developed and evolved in a variety of organisms, mostly insects and aquatic animals, in Germany in the late nineteenth and early twentieth centuries. Weismann proposed the theory of the continuity of germ-plasm, a theory of heredity. Weismann postulated that germ-plasm was the hereditary material in cells, and parents transmitted to their offspring only the germ-plasm present in germ-cells (sperm and egg cells) rather than somatic or body cells.

Format: Articles

Subject: People

Christiane Nusslein-Volhard (1942- )

Christiane Nusslein-Volhard studied how genes control embryonic development in flies and in fish in Europe during the twentieth and twenty-first centuries. In the 1970s, Nusslein-Volhard focused her career on studying the genetic control of development in the fruit fly Drosophila melanogaster. In 1988, Nusslein-Volhard identified the first described morphogen, a protein coded by the gene bicoid in flies. In 1995, along with Eric F. Wieschaus and Edward B.

Format: Articles

Subject: People

Where Are My Children? (1916)

Where Are My Children? is an anti-abortion silent film released in the United States on 16 April 1916. The film was directed by Lois Weber and Phillips Smalley and produced by Universal Film Manufacturing Company/Lois Weber Productions in Universal City, California. In the film, Weber tells a story of an attorney who wants to have children and raise a family, but his wife chooses to abort her pregnancies, fearing that having children will ruin her social activities. In the early 1900s, information about contraception was not freely available or legal to obtain.

Format: Articles

Subject: Publications

Studies of Thalidomide's Effects on Rodent Embryos from 1962-2008

Thalidomide is a sedative drug introduced to European markets on 1 October 1957 after extensive testing on rodent embryos to ensure its safety. Early laboratory tests in rodent populations showed that pregnant rodents could safely use it, so doctors prescribed Thalidomide to treat morning sickness in pregnant women. However, in humans Thalidomide interfered with embryonic and fetal development in ways not observed in rodent tests.

Format: Articles

Subject: Organisms, Reproduction, Disorders

Vegas Baby (2016)

In 2016, Runaway Films released the documentary Vegas Baby. The film, directed by Amanda Micheli, follows three women who struggle with infertility problems as they undergo in vitro fertilization, or IVF treatment, to become pregnant. In IVF treatment, a woman’s egg is fertilized by a sperm outside of the woman’s body. Once the sperm fertilizes the egg, a fertility doctor places the fertilized egg back into the woman’s uterus. The three women in the film enter the I Believe contest hosted by the Sher Institute of Reproductive Medicine in Las Vegas, Nevada.

Format: Articles

Subject: Outreach

California Proposition 71 (2004)

The California Stem Cell Research and Cures Act, also called Proposition 71, was a ballot
initiative proposed by California voters in 2004 to allocate three billion dollars of state
funds for stem cell research over ten years. Endorsed by California scientists and
patient-advocates, Prop 71 passed on 2 November 2004, amending the state constitution to make
stem cell research a constitutional right. In addition, Prop 71 led to the creation of the
California Institute for Regenerative Medicine (CIRM), in San Francisco, California to allocate

Format: Articles

Subject: Legal

The Hershey-Chase Experiments (1952), by Alfred Hershey and Martha Chase

In 1951 and 1952, Alfred Hershey and Martha Chase conducted a series of experiments at the Carnegie Institute of Washington in Cold Spring Harbor, New York, that verified genes were made of deoxyribonucleic acid, or DNA. Hershey and Chase performed their experiments, later named the Hershey-Chase experiments, on viruses that infect bacteria, also called bacteriophages. The experiments followed decades of scientists’ skepticism about whether genetic material was composed of protein or DNA.

Format: Articles

Subject: Experiments

“The Impact of Emotional and Physical Violence During Pregnancy on Maternal and Child Health at One Year Post-partum” (2011), by Sarah McMahon, Chien-Chung Huang, Paul Boxer, Judy L. Postmus

In 2011, Sarah McMahon and colleagues published “The Impact of Emotional and Physical Violence During Pregnancy on Maternal and Child Health at One Year Post-partum,” hereafter, “The Impact,” in the journal, Child and Youth Services Review. While existing studies had indicated negative chronic effects resulting from intimate partner violence, or IPV, such as miscarriage and premature labor, there was little research specifically analyzing the separate and joint effects of psychological and physical abuse on pregnant women and fetuses.

Format: Articles

Subject: Publications

Nelson v. Planned Parenthood Center of Tucson (1973)

The 1973 case Nelson v. Planned Parenthood Center of Tucson established the legality of abortion in Arizona. The Arizona Court of Appeals ruled that the Arizona Revised Statutes 13-211, 13-212, and 13-213, collectively called the Arizona abortion statutes, were unconstitutional. The statutes had made illegal receiving, providing, or advertising abortions. After the Arizona Appeals Court heard the case, it decided that the Arizona abortion statutes were constitutional. However, two weeks later the US Supreme Court decided in Roe v.

Format: Articles

Subject: Legal

Berthold Karl Hölldobler (1936– )

Berthold Karl Hölldobler studied social insects like ants in Europe and the US during the twentieth and early twenty-first century. He focused on the social behavior of ants, the evolutionary origins of social insects, and the way ants use chemicals to communicate with each other. Hölldobler’s research reached popular audiences through his co-authored Pulitzer Prize winning book The Ants and through an award winning nature documentary called Ameisen: Die heimliche Weltmacht (Ants: Nature’s Secret Power).

Format: Articles

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

The Human Genome Project (1990-2003)

The Human Genome Project (HGP) was an international scientific effort to sequence the entire human genome, that is, to produce a map of the base pairs of DNA in the human chromosomes, most of which do not vary among individuals. The HGP started in the US in 1990 as a public effort and included scientists and laboratories located in France, Germany, Japan, China, and the United Kingdom.

Format: Articles

Subject: Organizations

Mitochondrial DNA (mtDNA)

Mitochondrial DNA (mtDNA) is located outside the nucleus in the liquid portion of the cell (cytoplasm) inside cellular organelles called Mitochondria. Mitochondria are located in all complex or eukaryotic cells, including plant, animal, fungi, and single celled protists, which contain their own mtDNA genome. In animals with a backbone, or vertebrates, mtDNA is a double stranded, circular molecule that forms a circular genome, which ranges in size from sixteen to eighteen kilo-base pairs, depending on species. Each mitochondrion in a cell can have multiple copies of the mtDNA genome.

Format: Articles

Subject: Theories