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Effects of Prenatal Alcohol Exposure on Cardiac Development

A variety of developmental defects occur as a result of prenatal exposure to alcohol (ethanol) in utero. In humans, those defects are collectively classified as Fetal Alcohol Spectrum Disorders, with Fetal Alcohol Syndrome (FAS) representing the more severe defects. FAS is defined by pre- and post-natal growth retardation, minor facial abnormalities, and deficiencies in the central nervous system (CNS). In addition to those defects, prenatal exposure to alcohol impacts cardiogenesis, the developmental stage of heart formation.

Format: Articles

Subject: Disorders, Reproduction

Molecular Epigenetics and Development: Histone Conformations, DNA Methylation and Genomic Imprinting

Introduced by Conrad Hal Waddington in 1942, the concept of epigenetics gave scientists a new paradigm of thought concerning embryonic development, and since then has been widely applied, for instance to inheritable diseases, molecular technologies, and indeed the human genome as a whole. A genome contains an embedded intricate coding template that provides a means of genetic expression from the initial steps of embryonic development until the death of the organism. Within the genome there are two prominent components: coding (exons) and non-coding (introns) sequences.

Format: Articles

Subject: Theories

The Effects of Diethylstilbestrol on Embryonic Development

Estrogen plays a key role in the regulation of gene transcription. This is accomplished by its ability to act as a ligand and to bind to specific estrogen receptor (ER) molecules, such as ERα and ERβ, which act as nuclear transcription factors. There are three major nuclear estrogen receptor protein domains: the estrogen binding domain, the protein interaction domain, and the DNA binding domain.

Format: Articles

Subject: Disorders

Francis Harry Compton Crick (1916-2004)

Francis Harry Compton Crick, who co-discovered the structure of deoxyribonucleic acid (DNA) in 1953 in Cambridge, England, also developed The Central Dogma of Molecular Biology, and further clarified the relationship between nucleotides and protein synthesis. Crick received the Nobel Prize in Physiology or Medicine that he shared with James Watson and Maurice Wilkins in 1962 for their discovery of the molecular structure of DNA.

Format: Articles

Subject: People

Methylmercury and Human Embryonic Development

Methylmercury (MeHg) is an organic form of mercury that can damage the developing brains of human fetuses. Women who consume methylmercury during pregnancy can bear children who have neurological issues because methylmercury has toxic effects on the nervous system during embryonic development. During the third week of gestation, the human nervous system begins to form in the embryo. During this gestational period, the embryo's nervous system is particularly susceptible to the influence of neurotoxins like methylmercury that can result in abnormalities.

Format: Articles

Subject: Reproduction, Disorders

Thomas Henry Huxley (1825-1895)

In nineteenth century Great Britain, Thomas Henry Huxley proposed connections between the development of organisms and their evolutionary histories, critiqued previously held concepts of homology, and promoted Charles Darwin's theory of evolution. Many called him Darwin's Bulldog. Huxley helped professionalize and redefine British science. He wrote about philosophy, religion, and social issues, and researched and theorized in many biological fields.

Format: Articles

Subject: People

The Galton Society for the Study of the Origin and Evolution of Man (1918–1935)

Charles Benedict Davenport, Madison Grant, and Henry Fairfield Osborn founded the Galton Society for the Study of the Origin and Evolution of Man, or the Galton Society, in New York City, New York, in 1918. The Galton Society was a scientific society that promoted the study of humans in terms of race in service to the US eugenics movement. The Galton Society was named in honor of Francis Galton who first coined the term eugenics in 1883. Galton and other eugenics proponents claimed that the human species could improve through selective breeding that restricted who could have children.

Format: Articles

Subject: Organizations

Cornelia Isabella Bargmann (1961- )

Cornelia Isabella Bargmann studied the relationship between genes, neural circuits, and behavior in the roundworm Caenorhabditis elegans (C. elegans) during the twentieth and twenty-first centuries in the US. Bargmann’s research focused on how the sense of smell (olfaction) in the nematode word Caenorhabditis elegans. She provided a model to study how neural circuits develop and function in the human brain, as the genetic regulatory pathways are similar.

Format: Articles

Subject: People

“Infant Survival After Cesarean Section for Trauma” (1996), by John A. Morris, Jr. et al.

In the May 1996 edition of The Annals of Surgery, John A. Morris and his collaborators published “Infant Survival After Cesarean Section for Trauma,” in which they evaluate the use of emergency cesarean sections for the treatment of pregnant trauma patients. During a cesarean section, a physician removes a fetus from a pregnant woman through an incision in her abdomen and uterus. When a pregnant woman experiences trauma, physicians can perform an emergency cesarean section to remove the fetus and administer medical treatments that would not be possible while the woman is pregnant.

Format: Articles

Subject: Publications

Paternal Sperm Telomere Elongation and Its Impact on Offspring Fitness

Telomeres are structures at the ends of DNA strands that get longer in the DNA of sperm cells as males age. That phenomenon is different for most other types of cells, for which telomeres get shorter as organisms age. In 1992, scientists showed that telomere length (TL) in sperm increases with age in contrast to most cell of most other types. Telomeres are the protective caps at the end of DNA strands that preserve chromosomal integrity and contribute to DNA length and stability.

Format: Articles

Subject: Theories

Clinical Tests of Estrogen Injections on Women with Abnormal Menstrual Cycles During the Early 1920s by Jean Paul Pratt and Edgar Allen

In the early twentieth century US, Jean Paul Pratt and Edgar Allen conducted clinical experiments on women who had abnormal menstrual cycles. During the clinical tests, researchers injected the hormone estrogen into their patients to alleviate their menstrual ailments, which ranged from irregular cycles to natural menopause. The hormone estrogen plays a prominent role in the menstrual cycle by signaling the tissue lining the uterus (endometrium) to thicken in preparation for possible pregnancy.

Format: Articles

Subject: Experiments

Sheppard-Towner Maternity and Infancy Protection Act (1921)

In November 1921, US Congress passed the National Maternity and Infancy Protection Act, also called the Sheppard-Towner Act. The Act provided federal funds to states to establish programs to educate people about prenatal health and infant welfare. Advocates argued that it would curb the high infant mortality rate in the US.

Format: Articles

Subject: Legal, Outreach

CRISPR Acquired Resistance Against Viruses (2007)

In 2007, Philippe Horvath and his colleagues explained how bacteria protect themselves against viruses at Danisco, a Danish food company, in Dangé-Saint-Romain, France. Horvath and his team worked to improve the lifespan of bacteria cultures for manufacturing yogurt and ice cream. Specifically, they focused on bacteria’s resistance to bacteriophages, or viruses that infect bacteria. Horvath and his colleagues found that the bacteria used to culture yogurt, Streptococcus thermophilus, has an adaptive immune system that can target specific viruses that have previously infected the bacteria.

Format: Articles

Subject: Experiments

Ectoderm

Ectoderm is one of three germ layers--groups of cells that coalesce early during the embryonic life of all animals except maybe sponges, and from which organs and tissues form. As an embryo develops, a single fertilized cell progresses through multiple rounds of cell division. Eventually, the clump of cells goes through a stage called gastrulation, during which the embryo reorganizes itself into the three germ layers: endoderm, ectoderm, and mesoderm. After gastrulation, the embryo goes through a process called neurulation, which starts the development of nervous system.

Format: Articles

Subject: Processes

The Notch Signaling Pathway in Embryogenesis

The Notch signaling pathway is a mechanism in animals by which adjacent cells communicate with each other, conveying spatial information and genetic instructions for the animal's development. All multicellular animals utilize Notch signaling, which contributes to the formation, growth, and development of embryos (embryogenesis). Notch signaling also contributes to the differentiation of embryonic cells into various types of cells into various types of cells, such as neurons.

Format: Articles

Subject: Processes

"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

Etienne Geoffroy Saint-Hilaire (1772-1844)

Etienne Geoffroy Saint-Hilaire, commonly known as Geoffroy, studied animals, their anatomy and their embryos, and teratogens at the National Museum of Natural History in Paris, France in the eighteenth and nineteenth centuries. Geoffroy also helped develop several specialized fields in the life sciences, including experimental embryology. In his efforts to experimentally demonstrate the theory of recapitulation, Geoffroy developed techniques to intervene in the growth of embryos to see whether they would develop into different kinds of organisms.

Format: Articles

Subject: People

Francis Sellers Collins (1950- )

Francis Sellers Collins helped lead the International Human Genome Sequencing Consortium, which helped describe the DNA sequence of the human genome by 2001, and he helped develop technologies used in molecular genetics while working in the US in the twentieth and twenty-first centuries. He directed the US National Center for Human Genome Research (NCHGR), which became the National Human Genome Research Institute (NHGRI), of the US National Institutes of Health (NIH), located in Bethesda, Maryland, from 1993 to 2008.

Format: Articles

Subject: People

"On the Origin of Mitosing Cells" (1967), by Lynn Sagan

On the Origin of Mitosing Cells by Lynn Sagan appeared in the March 1967 edition of the Journal of Theoretical Biology. At the time the article was published, Lynn Sagan had divorced astronomer Carl Sagan, but kept his last name. Later, she remarried and changed her name to Lynn Margulis, and will be referred to as such throughout this article. In her 1967 article, Margulis develops a theory for the origin of complex cells that have enclosed nuclei, called eukaryotic cells.

Format: Articles

Subject: Publications, Theories

Hermaphrodites and the Medical Invention of Sex (1998), by Alice Domurat Dreger

Hermaphrodites and the Medical Invention of Sex, by historian of science Alice Domurat Dreger, was published in 1998 by Harvard University Press. In the book, Dreger describes how many doctors and scientists treated human hermaphrodites from the late nineteenth century to the early twentieth century. She states that during this time period, many physicians and scientists struggled to determine the nature sex, and to support a classification of sex as male or female, many physicians and scientists resorted to viewing a person's gonads for identification of his or her sex.

Format: Articles

Subject: Publications, Theories, Disorders

Purkinje Cells

Purkinje cells, also called Purkinje neurons, are neurons in vertebrate animals located in the cerebellar cortex of the brain. Purkinje cell bodies are shaped like a flask and have many threadlike extensions called dendrites, which receive impulses from other neurons called granule cells. Each cell also has a single projection called an axon, which transmits impulses to the part of the brain that controls movement, the cerebellum. Purkinje cells are inhibitory neurons: they secrete neurotransmitters that bind to receptors that inhibit or reduce the firing of other neurons.

Format: Articles

Subject: Theories

Lysogenic Bacteria as an Experimental Model at the Pasteur Institute (1915-1965)

Lysogenic bacteria, or virus-infected bacteria, were the primary experimental models used by scientists working in the laboratories of the Pasteur Institute in Paris, France, during the 1950s and 1960s. Historians of science have noted that the use of lysogenic bacteria as a model in microbiological research influenced the scientific achievements of the Pasteur Institute's scientists.

Format: Articles

Subject: Organisms, Experiments

"Mitochondrial DNA and Human Evolution" (1987), by Rebecca Louise Cann, Mark Stoneking, and Allan Charles Wilson

In 1987 Rebecca Louise Cann, Mark Stoneking, and Allan Charles Wilson published Mitochondrial DNA and Human Evolution in the journal Nature. The authors compared mitochondrial DNA from different human populations worldwide, and from those comparisons they argued that all human populations had a common ancestor in Africa around 200,000 years ago. Mitochondria DNA (mtDNA) is a small circular genome found in the subcellular organelles, called mitochondria.

Format: Articles

Subject: Publications, Theories

Hormone Releasing Intrauterine Devices

Hormone releasing intrauterine devices or hormonal IUDs are contraceptive devices placed in a woman’s uterus to prevent pregnancy by continuously releasing a low dose of certain hormones. Jouri Valter Tapani Luukkainen, a medical researcher at the University of Helsinki, introduced the first hormonal IUD in 1976. Luukkainen’s IUD was a plastic device shaped like a capital T.

Format: Articles

Subject: Technologies

Photograph 51, by Rosalind Franklin (1952)

On 6 May 1952, at King’s College London in London, England, Rosalind Franklin photographed her fifty-first X-ray diffraction pattern of deoxyribosenucleic acid, or DNA. Photograph 51, or Photo 51, revealed information about DNA’s three-dimensional structure by displaying the way a beam of X-rays scattered off a pure fiber of DNA. Franklin took Photo 51 after scientists confirmed that DNA contained genes. Maurice Wilkins, Franklin’s colleague showed James and Francis Crick Photo 51 without Franklin’s knowledge. Watson and Crick used that image to develop their structural model of DNA.

Format: Articles

Subject: Publications