Qr: switch:"CRY2/CIB1"
Showing 476 - 500 of 504 results
476.
The use of light for engineered control and reprogramming of cellular functions.
Abstract:
Could combating incurable diseases lie in something as simple as light? This scenario might not be too farfetched due to groundbreaking research in optogenetics. This novel scientific area, where genetically encoded photosensors transform light energy into specifically engineered biological processes, has shown enormous potential. Cell morphology can be changed, signaling pathways can be reprogrammed, and gene expression can be regulated all by the control of light. In biomedical applications where precise cell targeting is essential, non-invasive light has shown great promise. This article provides a summary of the recent advances that utilize light in genetic programming and precise control of engineered biological functions.
477.
The action mechanisms of plant cryptochromes.
Abstract:
Cryptochromes (CRY) are blue-light receptors that mediate various light responses in plants. The photoexcited CRY molecules undergo several biophysical and biochemical changes, including electron transfer, phosphorylation and ubiquitination, resulting in conformational changes to propagate light signals. Two modes of CRY signal transduction have recently been discovered: the cryptochrome-interacting basic-helix-loop-helix 1 (CIB)-dependent CRY2 regulation of transcription; and the SUPPRESSOR OF PHYA1/CONSTITUTIVELY PHOTOMORPHOGENIC1 (SPA1/COP1)-dependent cryptochrome regulation of proteolysis. Both CRY signaling pathways rely on blue light-dependent interactions between the CRY photoreceptor and its signaling proteins to modulate gene expression changes in response to blue light, leading to altered developmental programs in plants.
478.
Synthetic mammalian gene networks as a blueprint for the design of interactive biohybrid materials.
Abstract:
Synthetic biology aims at the rational design and construction of devices, systems and organisms with desired functionality based on modular well-characterized biological building blocks. Based on first proof-of-concept studies in bacteria a decade ago, synthetic biology strategies have rapidly entered mammalian cell technology providing novel therapeutic solutions. Here we review how biological building blocks can be rewired to interactive regulatory genetic networks in mammalian cells and how these networks can be transformed into open- and closed-loop control configurations for autonomously managing disease phenotypes. In the second part of this tutorial review we describe how the regulatory biological sensors and switches can be transferred from mammalian cell synthetic biology to materials sciences in order to develop interactive biohybrid materials with similar (therapeutic) functionality as their synthetic biological archetypes. We develop a perspective of how the convergence of synthetic biology with materials sciences might contribute to the development of truly interactive and adaptive materials for autonomous operation in a complex environment.
479.
Optogenetic control of cells and circuits.
Abstract:
The absorption of light by bound or diffusible chromophores causes conformational rearrangements in natural and artificial photoreceptor proteins. These rearrangements are coupled to the opening or closing of ion transport pathways, the association or dissociation of binding partners, the enhancement or suppression of catalytic activity, or the transcription or repression of genetic information. Illumination of cells, tissues, or organisms engineered genetically to express photoreceptor proteins can thus be used to perturb biochemical and electrical signaling with exquisite cellular and molecular specificity. First demonstrated in 2002, this principle of optogenetic control has had a profound impact on neuroscience, where it provides a direct and stringent means of probing the organization of neural circuits and of identifying the neural substrates of behavior. The impact of optogenetic control is also beginning to be felt in other areas of cell and organismal biology.
480.
The cryptochromes: blue light photoreceptors in plants and animals.
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Chaves, I
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Pokorny, R
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Byrdin, M
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Hoang, N
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Ritz, T
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Brettel, K
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Essen, LO
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van der Horst, GT
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Batschauer, A
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Ahmad, M
Abstract:
Cryptochromes are flavoprotein photoreceptors first identified in Arabidopsis thaliana, where they play key roles in growth and development. Subsequently identified in prokaryotes, archaea, and many eukaryotes, cryptochromes function in the animal circadian clock and are proposed as magnetoreceptors in migratory birds. Cryptochromes are closely structurally related to photolyases, evolutionarily ancient flavoproteins that catalyze light-dependent DNA repair. Here, we review the structural, photochemical, and molecular properties of cry-DASH, plant, and animal cryptochromes in relation to biological signaling mechanisms and uncover common features that may contribute to better understanding the function of cryptochromes in diverse systems including in man.
481.
Lights on and action! Controlling microbial gene expression by light.
Abstract:
Light-mediated control of gene expression and thus of any protein function and metabolic process in living microbes is a rapidly developing field of research in the areas of functional genomics, systems biology, and biotechnology. The unique physical properties of the environmental factor light allow for an independent photocontrol of various microbial processes in a noninvasive and spatiotemporal fashion. This mini review describes recently developed strategies to generate photo-sensitive expression systems in bacteria and yeast. Naturally occurring and artificial photoswitches consisting of light-sensitive input domains derived from different photoreceptors and regulatory output domains are presented and individual properties of light-controlled expression systems are discussed.
482.
Rapid blue-light-mediated induction of protein interactions in living cells.
Abstract:
Dimerizers allowing inducible control of protein-protein interactions are powerful tools for manipulating biological processes. Here we describe genetically encoded light-inducible protein-interaction modules based on Arabidopsis thaliana cryptochrome 2 and CIB1 that require no exogenous ligands and dimerize on blue-light exposure with subsecond time resolution and subcellular spatial resolution. We demonstrate the utility of this system by inducing protein translocation, transcription and Cre recombinase-mediated DNA recombination using light.
483.
The Cryptochrome Blue Light Receptors.
Abstract:
Cryptochromes are photolyase-like blue light receptors originally discovered in Arabidopsis but later found in other
plants, microbes, and animals. Arabidopsis has two cryptochromes, CRY1 and CRY2, which mediate primarily blue light
inhibition of hypocotyl elongation and photoperiodic control of fl oral initiation, respectively. In addition, cryptochromes
also regulate over a dozen other light responses, including circadian rhythms, tropic growth, stomata opening, guard
cell development, root development, bacterial and viral pathogen responses, abiotic stress responses, cell cycles, programmed
cell death, apical dominance, fruit and ovule development, seed dormancy, and magnetoreception. Cryptochromes
have two domains, the N-terminal PHR (Photolyase-Homologous Region) domain that bind the chromophore
FAD (flavin adenine dinucleotide), and the CCE (CRY C-terminal Extension) domain that appears intrinsically unstructured
but critical to the function and regulation of cryptochromes. Most cryptochromes accumulate in the nucleus,
and they undergo blue light-dependent phosphorylation or ubiquitination. It is hypothesized that photons excite electrons
of the fl avin molecule, resulting in redox reaction or circular electron shuttle and conformational changes of the
photoreceptors. The photoexcited cryptochrome are phosphorylated to adopt an open conformation, which interacts
with signaling partner proteins to alter gene expression at both transcriptional and posttranslational levels and consequently
the metabolic and developmental programs of plants.
484.
Photoexcited CRY2 interacts with CIB1 to regulate transcription and floral initiation in Arabidopsis.
Abstract:
Cryptochromes (CRY) are photolyase-like blue-light receptors that mediate light responses in plants and animals. How plant cryptochromes act in response to blue light is not well understood. We report here the identification and characterization of the Arabidopsis CIB1 (cryptochrome-interacting basic-helix-loop-helix) protein. CIB1 interacts with CRY2 (cryptochrome 2) in a blue light-specific manner in yeast and Arabidopsis cells, and it acts together with additional CIB1-related proteins to promote CRY2-dependent floral initiation. CIB1 binds to G box (CACGTG) in vitro with a higher affinity than its interaction with other E-box elements (CANNTG). However, CIB1 stimulates FT messenger RNA expression, and it interacts with chromatin DNA of the FT gene that possesses various E-box elements except G box. We propose that the blue light-dependent interaction of cryptochrome(s) with CIB1 and CIB1-related proteins represents an early photoreceptor signaling mechanism in plants.
485.
Integration of hepatitis B virus DNA in hepatocellular carcinoma.
Abstract:
Integration of hepatitis B virus (HBV) DNA into genomic DNA was investigated in 34 livers bearing hepatocellular carcinoma (HCC) by Southern blot hybridization using 32P-labeled, cloned and purified HBV DNA as a probe. Rehybridization of nitrocellulose paper with a probe containing only the cloning vector was performed after dehybridization to avoid possible false-positive results. Integrated HBV DNA was detected in all 9 hepatitis B surface antigen (HBsAg)-seropositive cases and 3 out of 25 (12%) HBsAg seronegative cases. The hybridization patterns of viral DNA were the same among several cancer nodules in two HCC cases with multiple liver tumors, indicating unicentric hepatocarcinogenesis in these two cases. These results, obtained with avoidance of false-positive results, showed that only a minority of HBsAg-seronegative HCC cases in Japan had demonstrable HBV DNA in the tumors studied by the Southern blot hybridization technique.
486.
Traumatic occlusion of internal carotid artery in an infant.
Abstract:
A case of an 11-months-old girl with traumatic occlusion of supraclinoid portion of internal carotid artery is reported. The patient died about 22 hours after the craniocerebral trauma.
487.
Sensitivity and precision of activated partial thromboplastin time (APTT) methods. A multicenter study.
Abstract:
The Activated Partial Thromboplastin Time (APTT) test, Cephotest, was compared to other APTT methods in current use in 4 specialized coagulation laboratories. In 3 of 4 laboratories, the sensitivity of Cephotest was superior (P less than 0.001) to that of the local APTT method. There was no statistically significant difference between the APTT methods with regard to precision of repetitive testing. In each laboratory, the normal range of Cephotest was estimated on freshly collected plasma samples from healthy subjects. A mean value between 28.8 and 35.8 s, with a standard deviation of 1.1-3.3 s, was obtained. It is concluded that the composition of the APTT method if of importance for the sensitivity of this test, but does not influence the precision of repetitive testing to a significant degree. The use of a standardized reagent facilitates comparison of the results obtained with the APTT method from one laboratory to another.
488.
Arrhythmogenic properties of thiamylal sodium in the dog.
Abstract:
Abstract not available.
489.
The specificity of heterophil antibodies in patients and healthy donors with no or minimal signs of infectious mononucleosis.
Abstract:
Over several years sera were collected from 14 heterophil-positive students or patients who did not fulfill minimal hematologic criteria for infectious mononucleosis (I.M.) The specificity of these heterophil reactions for I.M. was investigated by determining antibodies to Epstein-Barr virus-determined antigens, i.e., to viral capsid antigens (VCA), early antigens (EA), and EBV-associated nuclear antigens (EBNA). On the basis of detectable anti-EA and/or the early absence and late emergence of anti-EBNA, four of these 14 individuals showed evidence of a current or very recent primary Epstein-Barr virus infection. The other ten patients showed antibody patterns indicative of Epstein-Barr virus infections in the past, and no firm conclusions could be drawn with regard to the specificity of their heterophil reactions. It was assumed, however, that some represented atypical clinical forms of EBV infection and that timing of specimen collection was a factor in explaining the paucity of Downey cells. In three patients, the absorbed heterophil-positive reactions persisted with little change in titer for at least 22 mo and thus might represent false-positive tests.
490.
Beef liver L-Glutamate dehydrogenase mechanism: presteady state study of the catalytic reduction of 2.oxoglutarate by NADPH.
Abstract:
Abstract not available.
491.
Purification and properties of Escherichia coli dihydrofolate reductase.
Abstract:
Dihydrofolate reductase has been purified 40-fold to apparent homogeneity from a trimethoprim-resistant strain of Escherichia coli (RT 500) using a procedure that includes methotrexate affinity column chromatography. Determinations of the molecular weight of the enzyme based on its amino acid composition, sedimentation velocity, and sodium dodecyl sulfate gel electrophoresis gave values of 17680, 17470 and 18300, respectively. An aggregated form of the enzyme with a low specific activity can be separated from the monomer by gel filtration; treatment of the aggregate with mercaptoethanol or dithiothreitol results in an increase in enzymic activity and a regeneration of the monomer. Also, multiple molecular forms of the monomer have been detected by polyacrylamide gel electrophoresis. The unresolved enzyme exhibits two pH optima (pH 4.5 and pH 7.0) with dihydrofolate as a substrate. Highest activities are observed in buffers containing large organic cations. In 100 mM imidazolium chloride (pH 7), the specific activity is 47 mumol of dihydrofolate reduced per min per mg at 30 degrees. Folic acid also serves as a substrate with a single pH optimum of pH 4.5. At this pH the Km for folate is 16 muM, and the Vmax is 1/1000 of the rate observed with dihydrofolate as the substrate. Monovalent cations (Na+, K+, Rb+, and Cs+) inhibit dihydrofolate reductase; at a given ionic strength the degree of inhibition is a function of the ionic radius of the cation. Divalent cations are more potent inhibitors; the I50 of BaCl2 is 250 muM, as compared to 125 mM for KCl. Anions neither inhibit nor activate the enzyme.
492.
A comparison of the substrate specificities of endo-beta-N-acetylglucosaminidases from Streptomyces griseus and Diplococcus Pneumoniae.
Abstract:
Abstract not available.
493.
A comparison of the substrate specificities of endo-beta-N-acetylglucosaminidases from Streptomyces griseus and Diplococcus Pneumoniae.
Abstract:
Abstract not available.
494.
[Phoinatric and audiological aspects of autism (author's transl)].
Abstract:
The diagnosis of autism or autistic traits always necessitates exclusion of a primary or secondary speech or hearing disorder. The following findings are based on experience gained from 12 children with the diagnosis of early infantile autism. If an acoustic or speaking disorder is caused by brain damage, it will increasingly dominate the total symptomatology as the child matures. The more intensively the organic factor influences the picture, the more frequently a primary acoustic or speech disorder is found. This was observed in 6 cases, which can be diagnosed an "pseudo autistic". From the phoniatric and audiological view the type of autism syndrome as described by Kanner has so far not been confirmed.
495.
Delineation of the intimate details of the backbone conformation of pyridine nucleotide coenzymes in aqueous solution.
Abstract:
Abstract not available.
496.
Studies of oxygen binding energy to hemoglobin molecule.
Abstract:
Abstract not available.
497.
Pharmacological properties of new neuroleptic compounds.
Abstract:
RMI 61 140, RMI 61 144 and RMI 61 280 are newly synthetized N-[8-R-dibenzo(b,f)oxepin-10-yl]-N'-methyl-piperazine-maleates which show interesting psychopharmacologic effects. This work contains the results of a study performed with these three compounds, in order to demonstrate their neuropsycholeptic activity in comparison with chloropromazine (CPZ) and chlordiazepoxide (CPD). The inhibition of motility observed in mice shows that the compounds reduce the normal spontaneous motility as well as the muscle tone. The central-depressant activity is evidenced by increased barbiturate-induced sleep and a remarkable eyelid ptosis can also be observed. Our compounds do not show any activity on electroshock just as do CPZ and CPD. As to the antipsychotic outline, our compounds show strong reduction of lethality due to amphetamine in grouped mice and a strong antiapomorphine activity. They show also an antiaggressive effect and an inhibitory activity on avoidance behaviour much stronger than CPZ. We have also found extrapyramidal effects, as catalepsy, common to many tranquillizers of the kind of the standards used by us. As for vegetative phenomena, the compounds show hypotensive dose related action ranging from moderate to strong, probably due to an a-receptor inhibition. Adrenolytic activity against lethal doses of adrenaline, antiserotonin and antihistaminic effects, as well as other actions (hypothermia, analgesia, etc.) confirm that RMI 61 140, RMI 61 144 and RMI 61 280 are endowed with pharmacologic properties similar and more potent than those of CPZ. Studies on the metabolism of brain catecholamines show that they are similar to CPZ, although with less effect on dopamine level.
498.
Influence of a new virostatic compound on the induction of enzymes in rat liver.
Abstract:
The virostatic compound N,N-diethyl-4-[2-(2-oxo-3-tetradecyl-1-imidazolidinyl)-ethyl]-1-piperazinecarboxamide-hydrochloride (5531) was analyzed as to its effect on the induction of tryptophan-pyrrolase and tyrosineaminotransferase in rat liver. 1. The basic activity of the enzymes was not influenced by the substance either in normal or in adrenalectomized animals. 2. The induction of the enzymes by cortisone increased in the presence of the compound whereas the substrate induction remained unchanged. 3. The induction of tyrosine-aminotransferase by dexamethasonephosphate in tissue culture is inhibited if the dose of compound 5531 is higher than 5 mug/ml.
499.
Digitoxin metabolism by rat liver microsomes.
Abstract:
Abstract not available.
500.
Editorial: "Old lamps for new".
Abstract:
Abstract not available.
