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PSAT1
Phosphoserine aminotransferase (PSA) also known as phosphohydroxythreonine aminotransferase (PSAT) is an enzyme that in humans is encoded by the ''PSAT1'' gene. The protein encoded by this gene is likely a phosphoserine aminotransferase, based on similarity to proteins in mouse, rabbit, and ''Drosophila''. Alternative splicing of this gene results in two transcript variants encoding different isoforms. Clinical significance Homozygous or compound heterozygous mutations in ''PSAT1'' cause Neu–Laxova syndrome and phosphoserine aminotransferase deficiency. Model organisms Model organisms have been used in the study of PSAT1 function. A conditional knockout mouse line, called ''Psat1tm1a(KOMP)Wtsi'' was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists. Male and female animals underwent a standardized phenotypic screen to determine the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neu–Laxova Syndrome
Neu–Laxova syndrome (NLS, also known as Neu syndrome; Neu-Povysilová syndrome; or 3-phosphoglycerate dehydrogenase deficiency, neonate form) is a rare autosomal recessive disorder characterized by severe intrauterine growth restriction and multiple congenital malformations. Neu–Laxova syndrome is a very severe disorder, leading to stillbirth or death shortly after birth. It was first described by Dr. Richard Neu in 1971 and Dr. Renata Laxova in 1972 as a lethal disorder in siblings with multiple malformations. Neu–Laxova syndrome is an extremely rare disorder with less than 100 cases reported in medical literature. Signs and symptoms Neu-Laxova syndrome presents with severe malformations leading to prenatal or neonatal death. Typically, NLS involves characteristic facial features, decreased fetal movements and skin abnormalities. Fetuses or newborns with Neu–Laxova syndrome have typical facial characteristics which include proptosis (bulging eyes) with eyelid malformati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiography
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeutic") and industrial radiography. Similar techniques are used in airport security (where "body scanners" generally use backscatter X-ray). To create an image in conventional radiography, a beam of X-rays is produced by an X-ray generator and is projected toward the object. A certain amount of the X-rays or other radiation is absorbed by the object, dependent on the object's density and structural composition. The X-rays that pass through the object are captured behind the object by a detector (either photographic film or a digital detector). The generation of flat two dimensional images by this technique is called projectional radiography. In computed tomography (CT scanning) an X-ray source and its associated detectors rotate around the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weaning
Weaning is the process of gradually introducing an infant human or another mammal to what will be its adult diet while withdrawing the supply of its mother's milk. The process takes place only in mammals, as only mammals produce milk. The infant is considered to be fully weaned once it is no longer fed by any breast milk (or bottled substitute). Humans In some cultures, weaning progresses with the introduction of feeding the child food that has been prechewed by the parent along with continued breastfeeding, a practice known as premastication. The practice was important throughout human history in that it naturally gave a child a greatly improved protein source in addition to preventing iron deficiency. However, premasticated food from caregivers of lower socioeconomic status in areas of endemic diseases can result in the passing of the disease to the child. How and when to wean a human infant is controversial. The American Academy of Pediatrics recommends feeding a baby on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutant
In biology, and especially in genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. It is a characteristic that would not be observed naturally in a specimen. The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is in the nuclear genome. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene. Mutants arise by mutation Mutants arise by mutations occurring in pre-existing genomes as a result of errors of DNA replication or errors of DNA repair. Errors of replication often involve translesion synthesis by a DNA polymerase when it encounters and bypasses a damaged base in the temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotypic Screen
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 caddi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Knockout Mouse Consortium
The International Knockout Mouse Consortium (IKMC) is a scientific endeavour to produce a collection of mouse embryonic stem cell lines that together lack every gene in the genome, and then to distribute the cells to scientific researchers to create knockout mice to study. Many of the targeted alleles are designed so that they can generate both complete and conditional gene knockout mice. The IKMC was initiated on March 15, 2007 at a meeting in Brussels. By 2011, ''Nature'' reported that approximately 17,000 different genes have already been disabled by the consortium, "leaving only around 3,000 more to go". The consortium encompasses four major, high-throughput gene-targeted mutagenesis programs: the National Institutes of Health (NIH)-sponsored Knockout Mouse Program (KOMP) and state-funded Texas Institute for Genomic Medicine (TIGM) in the U.S., the North American Conditional Mouse Mutagenesis (NorCOMM) Program in Canada, and the European Conditional Mouse Mutagenesis (EUCOMM) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knockout Mouse
A knockout mouse, or knock-out mouse, is a genetically modified mouse (''Mus musculus'') in which researchers have inactivated, or "knocked out", an existing gene by replacing it or disrupting it with an artificial piece of DNA. They are important animal models for studying the role of genes which have been sequenced but whose functions have not been determined. By causing a specific gene to be inactive in the mouse, and observing any differences from normal behaviour or physiology, researchers can infer its probable function. Mice are currently the laboratory animal species most closely related to humans for which the knockout technique can easily be applied. They are widely used in knockout experiments, especially those investigating genetic questions that relate to human physiology. Gene knockout in rats is much harder and has only been possible since 2003. The first recorded knockout mouse was created by Mario R. Capecchi, Martin Evans, and Oliver Smithies in 1989, for whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model Organism
A model organism (often shortened to model) 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. Studying model organisms can be informative, but care must be taken when generalizing from one organism to another. In researching human disease, model organisms allow for better understanding the disease process without the added risk of harming an actual human. The species chosen will usually meet a determined taxonomic equivalency to humans, so as to react to disease or its treatment in a way that resembles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrobacter
''Citrobacter'' is a genus of Gram-negative coliform bacteria in the family Enterobacteriaceae. The species ''C. amalonaticus'', ''C. koseri'', and ''C. freundii'' can use citrate as a sole carbon source. ''Citrobacter'' species are differentiated by their ability to convert tryptophan to indole (''C. koseri'' is the only citrobacter to be commonly indole-positive), ferment lactose (''C. koseri'' is a lactose fermentor), and use malonate. ''Citrobacter'' shows the ability to accumulate uranium by building phosphate complexes. Clinical significance These bacteria can be found almost everywhere in soil, water, wastewater, etc. They can also be found in the human intestine. They are rarely the source of illnesses, except for infections of the GI Tract, urinary tract and infant meningitis and sepsis. ''Citrobacter freundii'' strains have inducible ''ampC'' genes encoding resistance to ampicillin and first-generation cephalosporins. In addition, isolates of ''Citrobacter'' may be r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella
''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type species and is further divided into six subspecies that include over 2,600 serotypes. ''Salmonella'' was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon. ''Salmonella'' species are non-spore-forming, predominantly motile enterobacteria with cell diameters between about 0.7 and 1.5 μm, lengths from 2 to 5 μm, and peritrichous flagella (all around the cell body, allowing them to move). They are chemotrophs, obtaining their energy from oxidation and reduction reactions, using organic sources. They are also facultative anaerobes, capable of generating ATP with oxygen ("aerobically") when it is available, or using other electron acceptors or fermentation ("anaerobically") when oxygen is not available. ''Salmonella'' spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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