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Homeotic Genes
Homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, insects, mammals, and plants. Homeotic genes often encode transcription factor proteins, and these proteins affect development by regulating downstream gene networks involved in body patterning. Mutations in homeotic genes cause displaced body parts (homeosis), such as antennae growing at the posterior of the fly instead of at the head. Mutations that lead to development of ectopic structures are usually lethal. Types There are several subsets of homeotic genes. They include many of the Hox and ParaHox genes that are important for segmentation. Hox genes are found in bilateral animals, including ''Drosophila'' (in which they were first discovered) and humans. Hox genes are a subset of the homeobox genes. The Hox genes are often conserved across species, so some of the Hox genes of ''Drosophila'' are homologous to those in humans. In general, Hox genes pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription Factors
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of 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 expressed in the desired 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 (as an activator), or blocking (as a repressor) the recruitment o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model Organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Model organisms are widely used to research human disease when human experimentation would be unfeasible or unethical. This strategy is made possible by the common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution. Research using animal models has been central to most of the achievements of modern medicine. It has contributed most of the basic knowledge in fields such as human physiology and biochemistry, and has played significant roles in fields such as neuroscience and infectious disease. The results have included the near- eradication of polio and the development of organ transplantation, and have benefited both humans and animals. From 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homeosis
In evolutionary developmental biology, homeosis is the transformation of one organ into another, arising from mutation in or misexpression of certain developmentally critical genes, specifically homeotic genes. In animals, these developmental genes specifically control the development of organs on their anteroposterior axis. In plants, however, the developmental genes affected by homeosis may control anything from the development of a stamen or petals to the development of chlorophyll. Homeosis may be caused by mutations in Hox genes, found in animals, or others such as the MADS-box family in plants. Homeosis is a characteristic that has helped insects become as successful and diverse as they are. Homeotic mutations work by changing segment identity during development. For example, the ''Ultrabithorax'' genotype gives a phenotype wherein metathoracic and first abdominal segments become mesothoracic segments. Another well-known example is '' Antennapedia'': a gain-of-function al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homeobox
A homeobox is a Nucleic acid sequence, DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. Mutations in a homeobox may change large-scale anatomical features of the full-grown organism. Homeoboxes are found within genes that are involved in the regulation of patterns of anatomical development (morphogenesis) in animals, fungus, fungi, plants, and numerous single cell eukaryotes. Homeobox genes encode homeodomain protein products that are transcription factors sharing a characteristic protein fold structure that binds DNA to regulate expression of target genes. Homeodomain proteins regulate gene expression and cell differentiation during early embryonic development, thus mutations in homeobox genes can cause developmental disorders. Homeosis is a term coined by William Bateson to describe the outright replacement of a discrete body part with another body part, e.g. antennapedia—replacement of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. Most carcinogens act by creating mutations in DNA that disrupt a cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division. The specific mechanisms for carcinogenic activity is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage dir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumor Suppressor
A tumor suppressor gene (TSG), or anti-oncogene, is a gene that regulates a cell (biology), cell during cell division and replication. If the cell grows uncontrollably, it will result in cancer. When a tumor suppressor gene is mutated, it results in a loss or reduction in its function. In combination with other genetic mutations, this could allow the cell to grow abnormally. The Loss-of-function mutation, loss of function for these genes may be even more significant in the development of human cancers, compared to the activation of oncogenes. TSGs can be grouped into the following categories: caretaker genes, gatekeeper genes, and more recently landscaper genes. Caretaker genes ensure stability of the genome via DNA repair and subsequently when mutated allow mutations to accumulate. Meanwhile, gatekeeper genes directly regulate cell growth by either inhibiting cell cycle progression or inducing apoptosis. Lastly, landscaper genes regulate growth by contributing to the surrounding e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cdx2
Homeobox protein CDX-2 is a protein that in humans is encoded by the ''CDX2'' gene. The CDX-2 protein is a homeobox transcription factor expressed in the nuclei of intestinal epithelial cells, playing an essential role in the development and function of the digestive system. ''CDX2'' is part of the ParaHox gene cluster, a group of three highly conserved developmental genes present in most vertebrate species. Together with ''CDX1'' and '' CDX4'', ''CDX2'' is one of three caudal-related genes in the human genome. Function In common with the two other Cdx genes, CDX2 regulates several essential processes in the development and function of the lower gastrointestinal tract (from the duodenum to the anus) in vertebrates. In vertebrate embryonic development, CDX2 becomes active in endodermal cells that are posterior to the developing stomach. These cells eventually form the intestinal epithelium. The activity of CDX2 at this stage is essential for the correct formation of the intest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blastoderm
A blastoderm (germinal disc, blastodisc) is a single layer of embryonic epithelial tissue that makes up the blastula. It encloses the fluid-filled blastocoel. Gastrulation follows blastoderm formation, where the tips of the blastoderm begins the formation of the ectoderm, mesoderm, and endoderm. Formation The blastoderm is formed when the oocyte plasma membrane begins cleaving by invagination, creating multiple cells that arrange themselves into an outer sleeve to the blastocoel. In oviparous animals In chicken eggs, the blastoderm represents a flat disc after embryonic fertilization. At the edge of the blastoderm is the site of active migration by most cells. DNA repair genes are highly expressed in chicken blastoderms. See also *Blastodisc *Embryology *Cleavage *Gastrulation Gastrulation is the stage in the early embryonic development of most animals, during which the blastula (a single-layered hollow sphere of cells), or in mammals, the blastocyst, is reorganized into a two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proboscipedia (pb Gene)
Proboscipedia (pb) is a protein coding gene in ''Drosophila melanogaster''. Function This hox gene participates in the development of the labial and maxillary palps and mouthparts in the Drosophila fly. The pb gene is known to regulate the location of the antenna, maxillary palp, tarsus and proboscis identities. Taxonomy Proboscipedia belongs to the Antennapedia (Antp) homeobox family and the Proboscipedia subfamily. A homeobox gene is a transcription factor in which a region known as a homeodomain binds to a target gene promoter and controls the differentiation and development of cells. The pb gene is evidenced to be associated with the Sex combs reduced (Scr) gene. Both of these are essential for determination of the proboscis, a long flexible mouthpart in many insects used for the purpose of sucking. Mutations Mutated In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral geno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antennapedia
''Antennapedia'' (abbreviated ''Antp'') is a Hox gene first discovered in ''Drosophila'' which controls the formation of legs during development. Loss-of-function mutations in the regulatory region of this gene result in the development of the second leg pair into ectopic antennae. By contrast gain-of-function alleles convert antennae into ectopic legs. This is just one illustration of the tendency of organisms to exhibit variations on a theme: modulated repetition. Legs and antennae are related to one another as much as molars are to incisors, fingers are to toes, and arms are to legs. ''Antp'' also refers to a gene complex (ANT-C) in ''Drosophila'' ending with the ''Antp'' gene. It is responsible for formation and differentiation of the thoracic and head segments of the fly's body. Origin of ''Antennapedia''-class homeobox gene The origin of the ancestor homeobox gene is an important aspect of the evolution of the ''Antp''-class ''Hox'' genes. Early evolution of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward B
Edward is an English male name. It is derived from the Anglo-Saxon name ''Ēadweard'', composed of the elements '' ēad'' "wealth, fortunate; prosperous" and '' weard'' "guardian, protector”. History The name Edward was very popular in Anglo-Saxon England, but the rule of the Norman and Plantagenet dynasties had effectively ended its use amongst the upper classes. The popularity of the name was revived when Henry III named his firstborn son, the future Edward I, as part of his efforts to promote a cult around Edward the Confessor, for whom Henry had a deep admiration. Variant forms The name has been adopted in the Iberian peninsula since the 15th century, due to Edward, King of Portugal, whose mother was English. The Spanish/Portuguese forms of the name are Eduardo and Duarte. Other variant forms include French Édouard, Italian Edoardo and Odoardo, German, Dutch, Czech and Romanian Eduard and Scandinavian Edvard. Short forms include Ed, Eddy, Eddie, Ted, Teddy and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (an insect of the Order (biology), order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly", or "banana fly". In the wild, ''D. melanogaster'' are attracted to rotting fruit and fermenting beverages, and are often found in orchards, kitchens and pubs. Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and Life history theory, life history evolution. ''D. melanogaster'' was the first animal to be Fruit flies in space, launched into space in 1947. As of 2017, six Nobel Prizes have been awarded to drosophilists for their work using the insect. ''Drosophila melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
