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Gene Oscillations
In molecular biology, an oscillating gene is a gene that is expressed in a rhythmic pattern or in periodic cycles. Oscillating genes are usually circadian and can be identified by periodic changes in the state of an organism. Circadian rhythms, controlled by oscillating genes, have a period of approximately 24 hours. For example, plant leaves opening and closing at different times of the day or the sleep-wake schedule of animals can all include circadian rhythms. Other periods are also possible, such as 29.5 days resulting from circalunar rhythms or 12.4 hours resulting from circatidal rhythms. Oscillating genes include both core clock component genes and output genes. A core clock component gene is a gene necessary for to the pacemaker. However, an output oscillating gene, such as the AVP gene, is rhythmic but not necessary to the pacemaker. History The first recorded observations of oscillating genes come from the marches of Alexander the Great in the fourth century B.C.Von Dr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptochrome
Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields in a number of species. The name ''cryptochrome'' was proposed as a ''portmanteau'' combining the '' chromatic'' nature of the photoreceptor, and the ''cryptogamic'' organisms on which many blue-light studies were carried out. The two genes ''Cry1'' and ''Cry2'' code the two cryptochrome proteins CRY1 and CRY2. In insects and plants, CRY1 regulates the circadian clock in a light-dependent fashion, whereas in mammals, CRY1 and CRY2 act as light-independent inhibitors of CLOCK-BMAL1 components of the circadian clock. In plants, blue-light photoreception can be used to cue developmental signals. Besides chlorophylls, cryptochromes are the only proteins known to form photoinduced radical-pairs ''in vivo''. These appear to enable some animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronobiology
Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος (''chrónos'', meaning "time"), and biology, which pertains to the study, or science, of life. The related terms ''chronomics'' and ''chronome'' have been used in some cases to describe either the molecular mechanisms involved in chronobiological phenomena or the more quantitative aspects of chronobiology, particularly where comparison of cycles between organisms is required. Chronobiological studies include but are not limited to comparative anatomy, physiology, genetics, molecular biology and behavior of organisms related to their biological rhythms. Other aspects include epigenetics, development, reproduction, ecology and evolution. The subject Chronobiology studies variations of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TOC1 Gene
Timing of CAB expression 1 is a protein that in ''Arabidopsis thaliana'' is encoded by the TOC1 gene. TOC1 is also known as two-component response regulator-like APRR1. TOC1 was the first plant gene that, when mutated, yielded a circadian phenotype. It codes for the transcription factor TOC1, which affects the period of plants' circadian rhythms: built-in, malleable oscillations that repeat every 24 hours. The gene codes for a transcriptional repressor, TOC1, one of five pseudo-response regulators (PRR) that mediate the period of the circadian clock in plants. The TOC1 protein is involved in the clock's evening loop, which is a repressilator that directly inhibits transcription of morning loop genes LHY and CCA1. Toc1 gene is expressed in most plant structures and cells, and has its locus on chromosome 5. Historical context Discovery The TOC1 gene was initially discovered by Prof. Andrew Millar and colleagues in 1995 while Millar was a graduate student. Millar developed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Elongated Hypocotyl
The Late Elongated Hypocotyl gene (LHY), is an oscillating gene found in plants that functions as part of their circadian clock. LHY encodes components of mutually regulatory negative feedback loops with Circadian Clock Associated 1 (CCA1) in which overexpression of either results in dampening of both of their expression. This negative feedback loop affects the rhythmicity of multiple outputs creating a daytime protein complex. LHY was one of the first genes identified in the plant clock, along with TOC1 and CCA1. LHY and CCA1 have similar patterns of expression, which is capable of being induced by light.Lu, S. X. , and S. M., Andronis. "CIRCADIAN CLOCK ASSOCIATED1 and LATE ELONGATED HYPOCOTYL Function Synergistically in the Circadian Clock of Arabidopsis" Plant Physiology Vol. 150. (2009): 834–843. Single loss-of-function mutants in both genes result in seemingly identical phenotypes, but LHY cannot fully rescue the rhythm when CCA1 is absent, indicating that they may only be p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterial Circadian Rhythms
Bacterial circadian rhythms, like other circadian rhythms, are endogenous "biological clocks" that have the following three characteristics: (a) in constant conditions (i.e. constant temperature and either constant light or constant darkness ) they oscillate with a period that is close to, but not exactly, 24 hours in duration, (b) this " free-running" rhythm is temperature compensated, and (c) the rhythm will entrain to an appropriate environmental cycle. Until the mid-1980s, it was thought that only eukaryotic cells had circadian rhythms. It is now known that cyanobacteria (a phylum of photosynthetic eubacteria) have well-documented circadian rhythms that meet all the criteria of bona fide circadian rhythms. In these bacteria, three key proteins whose structures have been determined can form a molecular clockwork that orchestrates global gene expression. This system enhances the fitness of cyanobacteria in rhythmic environments. History: are prokaryotes capable of circadian rhyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurospora
''Neurospora'' is a genus of Ascomycete fungi. The genus name, meaning "nerve spore" refers to the characteristic striations on the spores that resemble axons. The best known species in this genus is ''Neurospora crassa'', a common model organism in biology. ''Neurospora intermedia'' var. ''oncomensis'' is believed to be the only mold belonging to ''Neurospora'' which is used in food production (to make oncom). Characteristics ''Neurospora'' species are molds with broadly spreading colonies, with abundant production of ascomata. Ascomata are superficial or immersed, perithecial and ostiolate or cleistothecial and non-ostiolate, hairy or glabrous, dark coloured. Peridium membranaceous, asci cylindrical, clavate or subspherical, with a persistent or evanescent wall, usually with a thickened and non-amyloid annular structure at the apex, usually 8-spored. Ascospores broadly fusiform, ellipsoidal, or nearly spherical, unicellular, hyaline to yellowish brown or olive-brown, becomin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency (gene)
The frequency (''frq'') gene encodes the protein frequency (FRQ) that functions in the ''Neurospora crassa'' circadian clock. The FRQ protein plays a key role in circadian oscillator, serving to nucleate the negative element complex in the auto regulatory transcription-translation negative feedback-loop (TTFL) that is responsible for circadian rhythms in ''N. crassa''. Similar rhythms are found in mammals, ''Drosophila'' and cyanobacteria. Recently, FRQ homologs have been identified in several other species of fungi. Expression of frq is controlled by the two transcription factors white collar-1 (WC-1) and white collar-2 (WC-2) that act together as the White Collar Complex (WCC) and serve as the positive element in the TTFL. Expression of frq can also be induced through light exposure in a WCC dependent manner. Forward genetics has generated many alleles of ''frq'' resulting in strains whose circadian clocks vary in period length. Discovery The ''frq'' locus was discovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycle (gene)
''Cycle'' (''cyc'') is a gene in ''Drosophila melanogaster'' that encodes the CYCLE protein (CYC). The ''Cycle'' gene ''(''c''yc)'' is expressed in a variety of cell types in a circadian manner. It is involved in controlling both the sleep-wake cycle and circadian regulation of gene expression by promoting transcription in a negative feedback mechanism. The c''yc'' gene is located on the left arm of chromosome 3 and codes for a transcription factor containing a basic helix-loop-helix (bHLH) domain and a PAS domain. The 2.17 kb c''yc'' gene is divided into 5 coding exons totaling 1,625 base pairs which code for 413 aminos acid residues. Currently 19 alleles are known for c''yc'' ., accessdate=10 April 2013 Orthologs performing the same function in other species include ARNTL and ARNTL2. Function ''Cycle'' is primarily known for its role in the genetic transcription-translation feedback loop that generates circadian rhythms in ''Drosophila''. In the cell nucleus, the CYCLE pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeless (gene)
Timeless (''tim'') is a gene in multiple species but is most notable for its role in ''Drosophila'' for encoding TIM, an essential protein that regulates circadian rhythm. ''Timeless'' mRNA and protein oscillate rhythmically with time as part of a transcription-translation negative feedback loop involving the '' period'' (''per'') gene and its protein. Discovery In 1994, ''timeless'' was discovered through forward genetic screening performed by Jeffery L. Price while working in the lab of Michael W. Young. This gene was found when they noticed an arrhythmic ''tim''01 mutant via a P element screen. The tim01 mutation caused arrhythmic behavior, defined by the lack of ability to establish proper circadian rhythms. In 1995, the timeless gene was cloned by Amita Sehgal and partners in the lab of Michael W. Young. Unlike the Drosophila ''timeless'' gene, homologs have been discovered in other species that are non-essential for circadian rhythm. The discovery of ''timeless'' foll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Sleep Phase Disorder
Advanced Sleep Phase Disorder (ASPD), also known as the advanced sleep-phase type (ASPT) of circadian rhythm sleep disorder, is a condition that is characterized by a recurrent pattern of early evening (e.g. 7-9 PM) sleepiness and very early morning awakening (e.g. 2-4 AM). This sleep phase advancement can interfere with daily social and work schedules, and results in shortened sleep duration and excessive daytime sleepiness. The timing of sleep and melatonin levels are regulated by the body's central circadian clock, which is located in the suprachiasmatic nucleus in the hypothalamus. Symptoms Individuals with ASPD report being unable to stay awake until conventional bedtime, falling asleep early in the evening, and being unable to stay asleep until their desired waking time, experiencing early morning insomnia. When someone has advanced sleep phase disorder their melatonin levels and core body temperature cycle hours earlier than an average person. These symptoms must be presen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E-box
An E-box (enhancer box) is a DNA response element found in some eukaryotes that acts as a protein-binding site and has been found to regulate gene expression in neurons, muscles, and other tissues. Its specific DNA sequence, CANNTG (where N can be any nucleotide), with a palindromic canonical sequence of CACGTG, is recognized and bound by transcription factors to initiate gene transcription. Once the transcription factors bind to the promoters through the E-box, other enzymes can bind to the promoter and facilitate transcription from DNA to mRNA. Discovery The E-box was discovered in a collaboration between Susumu Tonegawa's and Walter Gilbert's laboratories in 1985 as a control element in immunoglobulin heavy-chain enhancer. They found that a region of 140 base pairs in the tissue-specific transcriptional enhancer element was sufficient for different levels of transcription enhancement in different tissues and sequences. They suggested that proteins made by specific tissues acted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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