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French Flag Model
The French flag model is a conceptual definition of a morphogen, described by Lewis Wolpert in the 1960s. A morphogen is defined as a signaling molecule that acts directly on cells (not through serial induction) to produce specific cellular responses dependent on morphogen concentration. During early development, morphogen gradients generate different cell types in distinct spatial order. Flag of France, French flag patterning is often found in combination with others: vertebrate limb development is one of the many phenotypes exhibiting French flag patterning overlapped with a complementary pattern (in this case Turing pattern). Overview In the French flag model, the Flag of France, French flag is used to represent the effect of a morphogen on cell differentiation: a morphogen affects cell states based on concentration, these states are represented by the different colors of the French flag: high concentrations activate a "blue" gene, lower concentrations activate a "white" gene, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen Cohen (biologist)
Steve, Steven or Stephen Cohen may refer to: Sportspeople * Steve Cohen (gymnast) (born 1946), American Olympic gymnast * Steve Cohen (judoka) (born 1955), American judoka and Olympian * Steve Cohen (wrestler) (born 1963), South African wrestler better known as Steve Simpson * Steven Cohen (footballer) (born 1986), French association football player Academics * Steven A. Cohen (academic) (born 1953), American environmental writer and academic * Stephen F. Cohen (1938–2020), American scholar specializing in Russian studies * Steven M. Cohen (born 1950), American sociologist * Stephen P. Cohen (1936–2019), American academic and senior fellow in foreign policy studies at the Brookings Institution * Stephen P. Cohen (Middle East scholar) (1945–2017), Canadian scholar specializing in Middle Eastern affairs Others * Steve Cohen (politician) (born 1949), U.S. congressman from Tennessee * Steve Cohen (businessman) (born 1956), hedge fund manager and owner of the New York Mets basebal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axolotl
The axolotl (; from ) (''Ambystoma mexicanum'') is a neoteny, paedomorphic salamander, one that Sexual maturity, matures without undergoing metamorphosis into the terrestrial adult form; adults remain Aquatic animal, fully aquatic with obvious external gills. This trait is somewhat unusual among amphibians, though this trait is not unique to axolotls, and this is apparent as they may be confused with the Tadpole, larval stage or Ambystoma#Species, other neotenic adult mole salamanders (''Ambystoma spp.''), such as the occasionally paedomorphic tiger salamander (''Ambystoma tigrinum, A. tigrinum'') widespread in North America; or with mudpuppies (''Necturus spp.''), which bear a superficial resemblance but are from a different Family (biology), family of salamanders. Axolotls originally inhabited a system of interconnected wetlands and lakes in the Mexican highlands; they were known to inhabit the smaller lakes of Lake Xochimilco, Xochimilco and Lake Chalco, Chalco, and are al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Gordon (theoretical Biologist)
Richard "Dick" Gordon (born November 6, 1943) is an American theoretical biologist. He was born in Brooklyn, New York, the eldest son of Jack Gordon, a salesman and American handball champion, and artist Diana Gordon. He is married to retired scientist Natalie K Björklund with whom he co-wrote his second book and several academic publications. He has three sons, Leland, Bryson and Chason Gordon and three stepchildren Justin, Alan and Lana Hunstad. Gordon was a professor at the University of Manitoba in Winnipeg, Manitoba from 1978 to 2011. He is retired and currently volunteers as a scientist for the Gulf Specimen Marine Laboratory in Panacea, Florida where he winters, and he holds an adjunct position in the Department of Obstetrics & Gynecology, Wayne State University. Gordon lives in Alonsa, Manitoba, Canada. Academic career Gordon was educated at University of Chicago where he did an undergraduate degree in mathematics and a PhD at University of Oregon in chemical physics u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphogenesis
Morphogenesis (from the Greek ''morphê'' shape and ''genesis'' creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of developmental biology along with the control of tissue growth and patterning of cellular differentiation. The process controls the organized spatial distribution of cells during the embryonic development of an organism. Morphogenesis can take place also in a mature organism, such as in the normal maintenance of tissue by stem cells or in regeneration of tissues after damage. Cancer is an example of highly abnormal and pathological tissue morphogenesis. Morphogenesis also describes the development of unicellular life forms that do not have an embryonic stage in their life cycle. Morphogenesis is essential for the evolution of new forms. Morphogenesis is a mechanical process involving forces that generate mechanical stress, strain, and mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinoic Acid
Retinoic acid (simplified nomenclature for all-''trans''-retinoic acid) is a metabolite of vitamin A1 (all-''trans''-retinol) that is required for embryonic development, male fertility, regulation of bone growth and immune function. All-''trans''-retinoic acid is required for chordate animal development, which includes all higher animals from fish to humans. During early embryonic development, all-''trans''-retinoic acid generated in a specific region of the embryo helps determine position along the embryonic anterior/posterior axis by serving as an intercellular signaling molecule that guides development of the posterior portion of the embryo. It acts through Hox genes, which ultimately control anterior/posterior patterning in early developmental stages. In adult tissues, the activity of endogenous retinoic acid appears limited to immune function and male fertility. All-''trans''-retinoic acid is the major occurring retinoic acid, while isomers like 13-''cis''- and 9-''cis''-r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription Factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription (genetics), transcription of genetics, genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The function of TFs is to regulate—turn on and off—genes in order to make sure that they are Gene expression, expressed in the desired Cell (biology), cells at the right time and in the right amount throughout the life of the cell and the organism. Groups of TFs function in a coordinated fashion to direct cell division, cell growth, and cell death throughout life; cell migration and organization (body plan) during embryonic development; and intermittently in response to signals from outside the cell, such as a hormone. There are approximately 1600 TFs in the human genome. Transcription factors are members of the proteome as well as regulome. TFs work alone or with other proteins in a complex, by promoting (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibroblast Growth Factor
Fibroblast growth factors (FGF) are a family of cell signalling proteins produced by the macrophages. They are involved in a wide variety of processes, most notably as crucial elements for normal development in animal cells. Any irregularities in their function will lead to a range of developmental defects. These growth factors typically act as a systemic or locally circulating molecules of extracellular origin that activate cell surface receptors. A defining property of FGFs is that they bind to heparin and to heparan sulfate. Thus, some are sequestered in the extracellular matrix of tissues that contains heparan sulfate proteoglycans, and released locally upon injury or tissue remodeling. Families In humans, 23 members of the FGF family have been identified, all of which are ''structurally'' related signaling molecules: * Members FGF1 through FGF10 all bind fibroblast growth factor receptors (FGFRs). FGF1 is also known as ''acidic fibroblast growth factor'', and FGF2 is al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wnt Signaling Pathway
In cellular biology, the Wnt signaling pathways are a group of signal transduction pathways which begin with proteins that pass signals into a cell through cell surface receptors. The name Wnt, pronounced "wint", is a portmanteau created from the names Wingless and Int-1. Wnt signaling pathways use either nearby cell-cell communication (paracrine) or same-cell communication (autocrine). They are highly evolutionarily conserved in animals, which means they are similar across animal species from fruit flies to humans. Three Wnt signaling pathways have been characterized: the canonical Wnt pathway, the noncanonical planar cell polarity pathway, and the noncanonical Wnt/calcium pathway. All three pathways are activated by the binding of a Wnt-protein ligand to a Frizzled family receptor, which passes the biological signal to the Dishevelled protein inside the cell. The canonical Wnt pathway leads to regulation of gene transcription, and is thought to be negatively regulated in part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonic Hedgehog
Sonic hedgehog protein (SHH) is a major signaling molecule of embryonic development in humans and animals, encoded by the ''SHH'' gene. This signaling molecule is key in regulating embryonic morphogenesis in all animals. SHH controls organogenesis and the organization of the central nervous system, limbs, digits and many other parts of the body. Sonic hedgehog is a morphogen that patterns the developing embryo using a concentration gradient characterized by the French flag model. This model has a non-uniform distribution of SHH molecules which governs different cell fates according to concentration. Mutations in this gene can cause holoprosencephaly, a failure of splitting in the cerebral hemispheres, as demonstrated in an experiment using SHH knock-out mice in which the forebrain midline failed to develop and instead only a single fused telencephalic vesicle resulted. Sonic hedgehog still plays a role in differentiation, proliferation, and maintenance of adult tissues. Abno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hedgehog (cell Signaling)
The Hedgehog signaling pathway is a signaling pathway that transmits information to embryonic cells required for proper cell differentiation. Different parts of the embryo have different concentrations of hedgehog signaling proteins. The pathway also has roles in the adult. Diseases associated with the malfunction of this pathway include cancer. The Hedgehog signaling pathway is one of the key regulators of animal development and is present in all bilaterians. The pathway takes its name from its polypeptide ligand, an intracellular signaling molecule called Hedgehog (''Hh'') found in fruit flies of the genus '' Drosophila''; fruit fly larvae lacking the ''Hh'' gene are said to resemble hedgehogs. ''Hh'' is one of Drosophila's segment polarity gene products, involved in establishing the basis of the fly body plan. The molecule remains important during later stages of embryogenesis and metamorphosis. Mammals have three Hedgehog homologues, Desert (DHH), Indian (IHH), and Soni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
