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Metafemale
A metafemale (or superfemale) is a low viability ''Drosophila'' fruit fly with a female phenotype in which the ratio of X chromosomes to sets of autosomes (A) exceeds 1.0. genic balance: a mechanism of sex determination, originally discovered in ''Drosophila'', that depends on the ratio of X chromosomes to sets of autosomes (A). Males develop when the X/A ratio is 0.5 or less, females develop when the X/A ratio is 1.0 or greater, an intersex develops when the ratio is between 0.5 and 1.0. ''See'' Appendix C, 1925, Bridges; metafemales, metamales, sex determination. metafemale: in ''Drosophila'', a female phenotype of relatively low viability in which the ratio of X chromosomes to sets of autosomes exceeds 1.0, previously called a ''superfemale''. ''See'' intersex, metamale. metamale: in ''Drosophila'', a poorly viabile male characterized by cells containing one X and three sets of autosomes, previously called a ''supermale''. ''See'' intersex, metafemale. superfemale: metafemale (''q. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamale
A metamale (or supermale) is a low viability ''Drosophila'' fruit fly with a male phenotype in which the ratio of X chromosomes to sets of autosomes (A) is less than 0.5. genic balance: a mechanism of sex determination, originally discovered in ''Drosophila'', that depends on the ratio of X chromosomes to sets of autosomes (A). Males develop when the X/A ratio is 0.5 or less, females develop when the X/A ratio is 1.0 or greater, an intersex develops when the ratio is between 0.5 and 1.0. ''See'' Appendix C, 1925, Bridges; metafemales, metamales, sex determination. metafemale: in ''Drosophila'', a female phenotype of relatively low viability in which the ratio of X chromosomes to sets of autosomes exceeds 1.0, previously called a ''superfemale''. ''See'' intersex, metamale. metamale: in ''Drosophila'', a poorly viabile male characterized by cells containing one X and three sets of autosomes, previously called a ''supermale''. ''See'' intersex, metafemale. superfemale: metafemale (''q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supermale
A metamale (or supermale) is a low viability '' Drosophila'' fruit fly with a male phenotype in which the ratio of X chromosomes to sets of autosomes (A) is less than 0.5. genic balance: a mechanism of sex determination, originally discovered in ''Drosophila'', that depends on the ratio of X chromosomes to sets of autosomes (A). Males develop when the X/A ratio is 0.5 or less, females develop when the X/A ratio is 1.0 or greater, an intersex develops when the ratio is between 0.5 and 1.0. ''See'' Appendix C, 1925, Bridges; metafemales, metamales, sex determination. metafemale: in ''Drosophila'', a female phenotype of relatively low viability in which the ratio of X chromosomes to sets of autosomes exceeds 1.0, previously called a ''superfemale''. ''See'' intersex, metamale. metamale: in ''Drosophila'', a poorly viabile male characterized by cells containing one X and three sets of autosomes, previously called a ''supermale''. ''See'' intersex, metafemale. superfemale: metafemale (' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila
''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly. One species of ''Drosophila'' in particular, '' D. melanogaster'', has been heavily used in research in genetics and is a common model organism in developmental biology. The terms "fruit fly" and "''Drosophila''" are often used synonymously with ''D. melanogaster'' in modern biological literature. The entire genus, however, contains more than 1,500 species and is very diverse in appea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book '' The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosome
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA. For example, humans have a diploid genome that usually contains 22 pairs of autosomes and one allosome pair (46 chromosomes total). The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labelled with their letters. By contrast, the allosome pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations of XYY, XXY, XXX, XXXX, XXXXX or XXYY, among other Salome combinations, are known to occur and usually cause developmental abnormalities. Autosomes still contain sexual determination genes even though they are not sex chromosomes. For example, the SRY gene on the Y chr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calvin Bridges
Calvin Blackman Bridges (January 11, 1889 – December 27, 1938) was an American scientist known for his contributions to the field of genetics. Along with Alfred Sturtevant and H.J. Muller, Bridges was part of Thomas Hunt Morgan's famous "Fly Room" at Columbia University. Early life Calvin Blackman Bridges was born in Schuyler Falls, New York in 1889 to the parents of Leonard Bridges and Charlotte Blackman. Tragically, Calvin's mother died when he was two years old, and his father died a year later, leaving the young Calvin an orphan. Bridges was subsequently taken in and raised by his grandmother. It took Bridges several years to complete high school, graduating when he was 20 years old. Despite this setback, he moved on to be an outstanding student at Columbia University in New York City, which he attended both undergraduate and postgraduate school. While taking a zoology class at Columbia, Bridges met Thomas Hunt Morgan. This started a relationship which would eventually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sex-determination System
A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most organisms that create their offspring using sexual reproduction have two sexes. In some species there are hermaphrodites. There are also some species that are only one sex due to parthenogenesis, the act of a female reproducing without fertilization. In some species, sex determination is genetic: males and females have different alleles or even different genes that specify their sexual morphology. In animals this is often accompanied by chromosomal differences, generally through combinations of XY, ZW, XO, ZO chromosomes, or haplodiploidy. The sexual differentiation is generally triggered by a main gene (a "sex locus"), with a multitude of other genes following in a domino effect. In other cases, sex of a fetus is determined by environmental variables (such as temperature). The details of some sex-determination systems are not yet fully und ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature'' cover the full ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curt Stern
Curt Stern (August 30, 1902 – October 23, 1981) was a German-born American geneticist. Life Curt Jacob Stern was born into a middle-class Jewish family in Hamburg, Germany on August 30, 1902. He was the first son of Earned S. Stern, born 1862 in England, who was interned during World War I, and Anna Stern, née Anna Liebrecht who was a schoolteacher (b. 1873). Her father C. Liebrecht was a teacher at the Israelitische Gemeindeschule Gleiwitz, a "Gymnasium" in Upper Silesia, with a PhD in mathematics and natural sciences at the University of Breslau. His father dealt in antiques and dental supplies, and his mother was a schoolteacher.A Guide to the Genetics Collections at the APS.http://www.amphilsoc.org/guides/glass/stern.htm access date 1-3-2014 The family moved to a suburb in Berlin shortly after his birth. As a child, he showed a strong interest in biology and natural history. He went to the "Hindenburgschule" in Berlin-Oberschoeneweide. Supported by two high school tea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Lancet
''The Lancet'' is a weekly peer-reviewed general medical journal and one of the oldest of its kind. It is also the world's highest-impact academic journal. It was founded in England in 1823. The journal publishes original research articles, review articles ("seminars" and "reviews"), editorials, book reviews, correspondence, as well as news features and case reports. ''The Lancet'' has been owned by Elsevier since 1991, and its editor-in-chief since 1995 has been Richard Horton. The journal has editorial offices in London, New York City, and Beijing. History ''The Lancet'' was founded in 1823 by Thomas Wakley, an English surgeon who named it after the surgical instrument called a lancet (scalpel). Members of the Wakley family retained editorship of the journal until 1908. In 1921, ''The Lancet'' was acquired by Hodder & Stoughton. Elsevier acquired ''The Lancet'' from Hodder & Stoughton in 1991. Impact According to the ''Journal Citation Reports'', the journal has a 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Center For Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is located in Bethesda, Maryland, and was founded in 1988 through legislation sponsored by US Congressman Claude Pepper. The NCBI houses a series of databases relevant to biotechnology and biomedicine and is an important resource for bioinformatics tools and services. Major databases include GenBank for DNA sequences and PubMed, a bibliographic database for biomedical literature. Other databases include the NCBI Epigenomics database. All these databases are available online through the Entrez search engine. NCBI was directed by David Lipman, one of the original authors of the BLAST sequence alignment program and a widely respected figure in bioinformatics. GenBank NCBI had responsibility for making available the GenBan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophilidae
The Drosophilidae are a diverse, cosmopolitan family of flies, which includes species called fruit flies, although they are more accurately referred to as vinegar or pomace flies. Another distantly related family of flies, Tephritidae, are true fruit flies because they are frugivorous, and include apple maggot flies and many pests. The best known species of the Drosophilidae is ''Drosophila melanogaster'', within the genus ''Drosophila'', also called the "fruit fly." ''Drosophila melanogaster'' is used extensively for studies concerning genetics, development, physiology, ecology and behaviour. Many fundamental biological mechanisms were discovered first in ''D. melanogaster.'' The fruit fly is mostly composed of post-mitotic cells, has a very short lifespan, and shows gradual aging. As in other species, temperature influences the life history of the animal. Several genes have been identified that can be manipulated to extend the lifespan of these insects. Additionally, ''Drosoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
