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Cryptochromes
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] |
CRY2
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 animals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circadian Rhythm
A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the environment (Entrainment (chronobiology), entrained by the environment). These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in animals, plants, fungi and cyanobacteria. The term ''circadian'' comes from the Latin ''wikt:circa#Latin, circa'', meaning "approximately", and ''dies'', meaning "day". Processes with 24-hour cycles are more generally called diurnal rhythms; diurnal rhythms should not be called circadian rhythms unless they can be confirmed as endogenous, and not environmental. Although circadian rhythms are endogenous, they are adjusted to the local environment by external cues called zeitgebers (German for "time givers"), which include light, temperature and redox cy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photolyase
Photolyases () are DNA repair enzymes that repair damage caused by exposure to ultraviolet light. These enzymes require visible light (from the violet/blue end of the spectrum) both for their own activation and for the actual DNA repair. The DNA repair mechanism involving photolyases is called photoreactivation. They mainly convert pyrimidine dimers into a normal pair of pyrimidine bases. Function Photolyases bind complementary DNA strands and break certain types of pyrimidine dimers that arise when a pair of thymine or cytosine bases on the same strand of DNA become covalently linked. The bond length of this dimerization is shorter than the bond length of normal B-DNA structure which produces an incorrect template for replication and transcription. The more common covalent linkage involves the formation of a cyclobutane bridge. Photolyases have a high affinity for these lesions and reversibly bind and convert them back to the original bases. Evolution Photolyase is a ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoreceptor Protein
Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina, phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria. They mediate light responses as varied as visual perception, phototropism and phototaxis, as well as responses to light-dark cycles such as circadian rhythm and other photoperiodisms including control of flowering times in plants and mating seasons in animals. Structure Photoreceptor proteins typically consist of a protein attached to a non-protein chromophore (sometimes referred as photopigment, even so photopigment may also refer to the photoreceptor as a whole). The chromophore reacts to light via photoisomerization or photoreduction, thus initiating a change of the receptor protein which triggers a signal transduction cascade. Chromophores found in photoreceptors include retinal (reti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoreceptor Protein
Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina, phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria. They mediate light responses as varied as visual perception, phototropism and phototaxis, as well as responses to light-dark cycles such as circadian rhythm and other photoperiodisms including control of flowering times in plants and mating seasons in animals. Structure Photoreceptor proteins typically consist of a protein attached to a non-protein chromophore (sometimes referred as photopigment, even so photopigment may also refer to the photoreceptor as a whole). The chromophore reacts to light via photoisomerization or photoreduction, thus initiating a change of the receptor protein which triggers a signal transduction cascade. Chromophores found in photoreceptors include retinal (reti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visible Spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' or simply light. A typical human eye will respond to wavelengths from about 380 to about 750 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 400–790 Terahertz (unit), terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well. The spectrum does not contain all the colors that the human visual system can distinguish. ''Excitation purity, Unsaturated colors'' such as pink, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radical Pair Mechanism
CIDNP (chemically induced dynamic nuclear polarization), often pronounced like "kidnip", is a nuclear magnetic resonance (NMR) technique that is used to study chemical reactions that involve radicals. It detects the non-Boltzmann (non-thermal) nuclear spin state distribution produced in these reactions as enhanced absorption or emission signals. CIDNP was discovered in 1967 by Bargon and Fischer, and, independently, by Ward and Lawler. Early theories were based on dynamic nuclear polarisation (hence the name) using the Overhauser Effect. The subsequent experiments, however, have found that in many cases DNP fails to explain CIDNP polarization phase. In 1969 an alternative explanation which relies on the nuclear spins affecting the probability of a radical pair recombining or separating. It is related to chemically induced dynamic electron polarization (CIDEP) insofar as the radical-pair mechanism explains both phenomena. Concept and experimental set-up The effect is detected by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Effects Of High-energy Visible Light
High-energy visible light (HEV light) is high-frequency, high-energy light in the violet/blue band from 400 to 450 nm in the visible spectrum, which has a number of biological effects, including those on the eye. HEV light may be a cause of age-related macular degeneration. Some sunglasses and beauty creams specifically block HEV, for added marketing value. Currently, a 2019 report by France's Agency for Food, Environmental and Occupational Health & Safety (ANSES) supports the 2010 result on the adverse effect of blue LED light (400-450 nm spike) on the eye, which can lead to impaired vision. It highlights short-term effects on the retina linked to intense exposure to blue LED light, and long-term effects linked to the onset of age-related macular degeneration. Although few studies have examined occupational causes of macular degeneration, they show that long-term sunlight exposure, specifically its blue-light component, is associated with macular degeneration in outdoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555. In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flavoproteins
Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin. Flavoproteins are involved in a wide array of biological processes, including removal of radicals contributing to oxidative stress, photosynthesis, and DNA repair. The flavoproteins are some of the most-studied families of enzymes. Flavoproteins have either FMN or FAD (flavin adenine dinucleotide) as a prosthetic group or as a cofactor. The flavin is generally tightly bound (as in adrenodoxin reductase, wherein the FAD is buried deeply). About 5-10% of flavoproteins have a covalently linked FAD. Based on the available structural data, FAD-binding sites can be divided into more than 200 different types. 90 flavoproteins are encoded in the human genome; about 84% require FAD, and around 16% require FMN, whereas 5 proteins require both. Flavoproteins are mainly located in the mitochondria. Of all flavoproteins, 90% perform redox reactions and the other 10% are transferases, lyases, isomerases, ligase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabidopsis Thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land. A winter annual with a relatively short lifecycle, ''A. thaliana'' is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, ''A. thaliana'' has a relatively small genome around 135 mega base pairs. It was the first plant to have its genome sequenced, and is a popular tool for understanding the molecular biology of many plant traits, including flower development and light sensing. Description ''Arabidopsis thaliana'' is an annual (rarely biennial) plant, usually growing to 20–25 cm tall. The leaves form a rosette at the base of the plant, with a few leaves also on the flowering stem. The basal leaves are green to slightly purplish in color, 1.5–5 cm long, and 2–10 mm broad, with an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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