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Displaying 126 - 150 of 1101 items.

Wilhelm Friedrich Phillip Pfeffer (1845-1920)

Wilhelm Friedrich Phillip Pfeffer studied plants in Germany during the late nineteenth and early twentieth centuries. He started his career as an apothecary, but Pfeffer also studied plant physiology, including how plants move and react to changes in light, temperature, and osmotic pressure. He created the Pfeffer Zelle apparatus, also known as the Pfeffer Cell, to study osmosis in plants. PfefferÕs experiments led to new theories about the structure and development of plants.

Format: Articles

Subject: People

Tissue Engineering

Tissue engineering is a field of regenerative medicine that integrates the knowledge of scientists, physicians, and engineers into the construction or reconstruction of human tissue. Practitioners of tissue engineering seek to repair, replace, maintain, and enhance the abilities of a specific tissue or organ by means of living cells. More often than not stem cells are the form of living cells used in this technology. Tissue engineering is one of the disciplines involved in translating knowledge of developmental biology into the clinical setting.

Format: Articles

Subject: Processes

Frank Rattray Lillie (1870-1947)

Frank R. Lillie was born in Toronto, Canada, on 27 June 1870. His mother was Emily Ann Rattray and his father was George Waddell Little, an accountant and co-owner of a wholesale drug company. While in high school Lillie took up interests in entomology and paleontology but went to the University of Toronto with the aim of studying ministry. He slowly became disillusioned with this career choice and decided to major in the natural sciences. It was during his senior year that he developed his lifelong interest in embryology.

Format: Articles

Subject: People

Karl Oskar Illmensee (1939–)

Karl Oskar Illmensee studied the cloning and reproduction of fruit flies, mice, and humans in the US and Europe during the twentieth and twenty-first centuries. Illmensee used nuclear transfer techniques (cloning) to create early mouse embryos from adult mouse cells, a technique biologists used in later decades to help explain how embryonic cells function during development. In the early 1980s, Illmensee faced accusations of fraud when others were unable to replicate the results of his experiments with cloned mouse embryos.

Format: Articles

Subject: People, People

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

The Cell in Development and Inheritance (1900), by Edmund Beecher Wilson

The Cell in Development and Inheritance, by Edmund Beecher Wilson, provided a textbook introduction to cell biology for generations of biologists in the twentieth century. In his book, Wilson integrated information about development, inheritance, chromosomes, organelles, and the structure and functions of cells. First published in 1896, the book started with 371 pages, grew to 483 pages in the second edition that appeared in 1900, and expanded to 1,231 pages by the third and final edition in 1925.

Format: Articles

Subject: Publications

Pre- and Post-natal Growth Deficiencies and Fetal Alcohol Syndrome

Maternal consumption of alcohol (ethanol) during pregnancy can inhibit prenatal growth, resulting in fetuses that are small for gestational age. Those prenatal growth deficiencies can have lasting consequences for early childhood development and are often reflected by low weight and stature. Those alcohol-induced pre- and post-natal growth deficiencies ("failure to thrive") are among the abnormal developmental criteria used to identify Fetal Alcohol Syndrome (FAS). FAS is characterized by minor facial abnormalities and deficiencies of the central nervous system as well.

Format: Articles

Subject: Disorders

"Cell Deaths in Normal Vertebrate Ontogeny" (1951), by Alfred Glücksmann

The review article “Cell Deaths in Normal Vertebrate Ontogeny” (abbreviated as “Cell Deaths”) was published in Biological Reviews of the Cambridge Philosophy Society in 1951. The author, Alfred Glücksmann, was a German developmental biologist then working at the Strangeways Research Laboratory, Cambridge, England. In “Cell Deaths,” Glücksmann summarizes observations about cell death in normal vertebrate development that he had compiled from literature published during the first half of the twentieth century.

Format: Articles

Subject: Publications

“Explaining Recent Declines in Adolescent Pregnancy in the United States: The Contribution of Abstinence and Improved Contraceptive Use” (2007), by John S. Santelli, Laura Duberstein Lindberg, Lawrence B. Finer, and Susheela Singh

In “Explaining Recent Declines in Adolescent Pregnancy in the United States: The Contribution of Abstinence and Improved Contraceptive Use,” hereafter “Explaining Recent Declines,” researchers John S. Santelli, Laura Duberstein Lindberg, Lawrence B. Finer, and Susheela Singh discuss what led to the major decline in US adolescent pregnancy rates from 1995 to 2002. Working with the Guttmacher Institute, a reproductive health research organization, they found that the decline in US adolescent pregnancy rates between 1995 and 2002 was primarily due to improved contraceptive use.

Format: Articles

Subject: Publications, Reproduction

Curt Jacob Stern (1902-1981)

Curt Jacob Stern studied radiation and chromosomes in humans and fruit flies in the United States during the twentieth century. He researched the mechanisms of inheritance and of mitosis, or the process in which the chromosomes in the nucleus of a single cell, called the parent cell, split into identical sets and yield two cells, called daughter cells. Stern worked on the Drosophila melanogaster fruit fly, and he provided early evidence that chromosomes exchange genetic material during cellular reproduction.

Format: Articles

Subject: People

Endothelium

The endothelium is the layer of cells lining the blood vessels in animals. It weighs more than one kilogram in adult humans, and it covers a surface area of 4000 to 7000 square meters. The endothelium is the cellular interface between the circulating blood and underlying tissue. As the medium between these two sets of tissues, endothelium is part of many normal and disease processes throughout the body.

Format: Articles

Subject: Processes, Theories

Edwin Grant Conklin (1863-1952)

Edwin Grant Conklin was born in Waldo, Ohio, on 24 November 1863 to parents Nancy Maria Hull and Dr. Abram V. Conklin. Conklin's family was very religious and he seriously considered a theistic path before choosing a career in academics. Conklin's scientific work was primarily in the areas of embryology, cytology, and morphology, though many questions regarding the relationships between science, society, and philosophy had an influence on both his writings and academic lectures.

Format: Articles

Subject: People

Victor Jollos (1887-1941)

Victor Jollos studied fruit flies and
microorganisms in Europe and the US, and he introduced the concept of
Dauermodifikationen in the early 1900s. The concept of
Dauermodifikationen refers to environmentally-induced traits that are
heritable for only a limited number of generations. Some scientists
interpreted the results of Jollos's work on Paramecium and Drosophila as
evidence for cytoplasmic inheritance. Jollos was forced to emigrate from
Germany to the United States due to anti-semitic government policies in

Format: Articles

Subject: People

Elizabeth Dexter Hay (1927–2007)

Elizabeth Dexter Hay studied the cellular processes that affect development of embryos in the US during the mid-twentieth and early twenty-first centuries. In 1974, Hay showed that the extracellular matrix, a collection of structural molecules that surround cells, influences cell behavior. Cell growth, cell migration, and gene expression are influenced by the interaction between cells and their extracellular matrix.

Format: Articles

Subject: People

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

Assisted Human Reproduction Act (2004)

The Assisted Human Reproduction Act (AHR Act) is a piece of federal legislation passed by the Parliament of Canada. The Act came into force on 29 March 2004. Many sections of the Act were struck down following a 2010 Supreme Court of Canada ruling on its constitutionality. The AHR Act sets a legislative and regulatory framework for the use of reproductive technologies such as in vitro fertilization and related services including surrogacy and gamete donation. The Act also regulates research in Canada involving in vitro embryos.

Format: Articles

Subject: Legal, Reproduction, Ethics

Telomeres and Telomerase in Cellular Aging (Senescence)

Telomeres are sequences of DNA on the ends of chromosomes that protect chromosomes from sticking to each other or tangling, which could cause irregularities in normal DNA functions. As cells replicate, telomeres shorten at the end of chromosomes, which correlates to senescence or cellular aging. Integral to this process is telomerase, which is an enzyme that repairs telomeres and is present in various cells in the human body, especially during human growth and development.

Format: Articles

Subject: Theories

Alexis Carrel's Immortal Chick Heart Tissue Cultures (1912-1946)

In an effort to develop tissue culture techniques for long-term tissue cultivation, French surgeon and biologist Alexis Carrel, and his associates, produced and maintained a series of chick heart tissue cultures at the Rockefeller Institute in New York City. From 1912 to 1946, this series of chick heart tissue cultures remained alive and dividing. Since the duration of this culture greatly exceeded the normal chick life span, the cells were deemed immortal.

Format: Articles

Subject: Experiments

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

Spemann-Mangold Organizer

The Spemann-Mangold organizer, also known as the Spemann organizer, is a cluster of cells in the developing embryo of an amphibian that induces development of the central nervous system. Hilde Mangold was a PhD candidate who conducted the organizer experiment in 1921 under the direction of her graduate advisor, Hans Spemann, at the University of Freiburg in Freiburg, German. The discovery of the Spemann-Mangold organizer introduced the concept of induction in embryonic development.

Format: Articles

Subject: Processes

Gene Transfer Strategy Used to Treat Tay - Sachs Disease (2005), by Sabata Martino’s Research Group

In the early 2000s, Sabata Martino and a team of researchers in Italy and Germany showed that they could reduce the symptoms of Tay-Sachs in afflicted mice by injecting them with a virus that infected their cells with a gene they lacked. Tay-Sachs disease is a fatal degenerative disorder that occurs in infants and causes rapid motor and mental impairment, leading to death at the ages of three to five. In gene therapy, researchers insert normal genes into cells that have missing or defective genes in order to correct genetic disorders.

Format: Articles

Subject: Experiments

Charles Bonnet (1720-1793)

Charles Bonnet was a naturalist and philosopher in the mid eighteenth century. His most important contribution to embryology was the discovery of parthenogenesis in aphids, proving that asexual reproduction of offspring was possible. In his later life, he was an outspoken defender of the theory of generation now known as preformationism, which stated that offspring exist prior to conception preformed in the germ cell of one of their parents.

Format: Articles

Subject: People

Effects of Prenatal Alcohol Exposure on Cerebellum Development

Prenatal exposure to alcohol (ethanol) results in a continuum of physical, neurological, behavioral, and learning defects collectively grouped under the heading fetal alcohol spectrum disorders (FASD). Fetal alcohol syndrome (FAS) is the most severe combination of these defects under this heading, and is characterized by pre- and postnatal growth deficiencies, facial abnormalities, and defects of the central nervous system (CNS).

Format: Articles

Subject: Disorders, Reproduction

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

Percivall Pott (1714-1788)

Percivall Pott was a physician in England during the eighteenth century who identified soot as the cause of chimney sweeps' scrotal cancer, later called testicular cancer. In the 1770s, Pott observed that scrotal cancer commonly afflicted chimney sweeps, the young boys sent up into chimneys to clean away the soot left over from fires, and he hypothesized that the soot inside chimneys might cause that type of cancer. Pott was one of the first doctors to identify some environmental factor as causing cancer.

Format: Articles

Subject: People