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At least 289 records · Page 16Linked to original sources
PubMed1989

Comparison of Photomorphogenic Responses to UV Light in Red and White Cabbage (Brassica oleracea L.).

Photoinhibition of hypocotyl growth in white cabbage (Brassica oleracea L., cv "Bianco Brunswick") is controlled by UV absorbing receptor(s) and the phytochrome system, while in red cabbage (cv "Rosso Olandese tardivo invernale") phytochrome can act without any requirement for the action of a specific UV receptor. Similar results have been obtained for the photoregulation of anthocyanin production. Twenty-four hour preirradiations with UV light or 692 nanometers light lead to the same increase in responsiveness of the system toward Pfr in a following dark period, suggesting a phytochrome promotion of subsequent light induction for both.

Journal Article↗
PubMed1962

Genetic transduction with staphylophage.

Korman, Ruth Z. (Elmira College, Elmira, N.Y.) and David T. Berman. Genetic transduction with staphylophage. J. Bacteriol. 84:228-236. 1962.-Transduction by crude lysates obtained by ultraviolet-light induction of phage 53 lysogenic derivatives of Staphylococcus aureus NCTC 8511 has been confirmed. A defined medium and sugar-differential medium were developed, permitting demonstration of transmission of sugar-fermentation loci. The range of transmissible markers has been extended to include free-coagulase production as well as antibiotic-resistance markers. A rare class of heterogeneous streptomycin-resistant transformed clones was obtained. These were assumed to be heterogenotic.

Coagulase↗
PubMed1968

Deoxyribonucleic acid replication in lambda bacteriophage mutants.

After ultraviolet light induction of Escherichia coli K-12 strain W3350(lambda), several structural intermediate forms of phage deoxyribonucleic acid (DNA) are synthesized. The early defective lysogens of lambda, sus O(8), sus P(3), and T(11), were found to synthesize none of the DNA structural intermediates. A lysogen believed to be defective in all known phage activities, lambdasus N(7), was found to be able to synthesize an early phage DNA intermediate. The lysogen lambdasus Q(21), defective in late phage functions, is able to synthesize the early phage DNA intermediate and a concatenated molecule of greater molecular weight than the mature lambda DNA.

Centrifugation, Density Gradient↗
PubMed1999

Molecular cloning and characterization of a cDNA for an iron-superoxide dismutase in rice (Oryza sativa L.).

We have isolated a cDNA encoding Fe-SOD from rice (Oryza sativa L.). The deduced amino acid sequence consists of a polypeptide with 255 amino acids, including a putative transit peptide (40 a.a.) in amino-terminal residues. This sequence is similar to the known plant Fe-SODs but not classified in the group of known Fe-SODs. The metal analysis and SOD assays of the partial purified recombinant protein expressed in E. coli showed that this cDNA encodes an iron-containing SOD. However this SOD activity was not inhibited by the treatment with hydrogen peroxide, which was expected to inhibit known Fe-SOD activity. mRNA of rice Fe-SOD was detected in all vegetative tissues examined, being especially abundant in calli, and strongly increased by light induction. These results suggested that this cDNA encodes rice Fe-SOD, which is apparently distinct from known plant Fe-SODs.

Amino Acid Sequence↗
PubMed2000

GFP fluorescence reports Period 1 circadian gene regulation in the mammalian biological clock.

Endogenous cyclic activation of a specific set of genes, including Period 1 (Per1), drive circadian rhythms in the suprachiasmatic nucleus (SCN), a biological clock nucleus of the brain. We have produced transgenic mice in which a degradable form of recombinant jellyfish green fluorescent protein (GFP) is driven by the mouse Period 1 (mPer1) gene promoter. GFP protein is expressed in the circadian neural structures of the retina and SCN. Fluorescent signals are resolved at the level of individual neurons. mPer1-driven GFP fluorescence intensity reports light-induction and circadian rhythmicity in SCN neurons. This circadian reporter transgene captures the gene expression dynamics of living biological clock neurons and ensembles, providing a novel view of this brain function.

Animals↗
PubMedDate not supplied

[Electro-clinical concordance for childhood absence epilepsy in monozygotic twins].

INTRODUCTION AND OBJECTIVE: The objective of the study was to analyze the EEG tracings during the seizures of two monozygotic twins, shown on molecular analysis, diagnosed as having infantile epilepsy with absences. The recordings are particularly interesting since the genotypes of the patients are identical. This allowed comparison between the similarities and differences in discharges so that they could be better defined. RESULTS: The 3 Hz spike and wave complexes were the same as the classical descriptions in typical absences. No 'W' spike and wave complexes morphology, discharge fragmentation or light induction of the discharges were observed. There was some differences in the duration of absences, which were much shorter in one twin girl. The duration of the seizures was variable, and sometimes similar to that described as characteristic in other types of generalized idiopathic epilepsies with absences. It would seem therefore that the duration of the seizure is not a criterion for differentiation between the different types of generalized idiopathic epilepsies. CONCLUSION: Concordance, both clinical and of seizure EEG recordings in our patients confirmed that there is a specific electroclinical phenotype in infantile epilepsy with absences, although individual variations may also occur.

Child↗
PubMed1992

Immunological characterization of the complex forms of chloroplast translational initiation factor 2 from Euglena gracilis.

Euglena gracilis chloroplast translational initiation factor 2 (IF-2chl) occurs in several complex forms ranging in molecular mass from 200 to 800 kDa. Subunits of 97 to greater than 200 kDa have been observed in these preparations. Two monoclonal antibodies were prepared against the 97-kDa subunits of IF-2chl. Both of these antibodies recognize all of the higher molecular mass forms of this factor, suggesting that these subunits are closely related. Gel filtration chromatography indicates that the higher molecular mass subunits of IF-2chl are present in the higher molecular mass complexes, whereas the smaller subunits are present in the 200-400 kDa forms of IF-2chl. Probing extracts of light-induced and dark-grown cells with the antibodies indicates that the light induction of this chloroplast factor results from the synthesis of new polypeptide rather than from the activation of an inactive precursor form of the protein. Both the higher and lower molecular mass subunits of IF-2chl are present in 30 S initiation complexes as indicated by Western analysis. The binding of IF-2chl to chloroplast 30 S ribosomal subunits requires the presence of GTP, but does not require fMet-tRNA, messenger RNA, or other initiation factors. Neither polyclonal nor monoclonal antibodies against E. gracilis IF-2chl cross-react with Escherichia coli IF-2 or with animal mitochondrial IF-2.

Animals↗
PubMed1989

Identification and characterization of cap-binding proteins from yeast.

Photochemical cross-linking of Saccharomyces cerevisiae ribosomal salt wash preparations to cap-labeled mRNA reveals, in addition to the previously characterized 24-kDa cap-binding protein (eIF-4E), the presence of two novel cap-binding proteins (CBPs) of apparent molecular masses of 96 and 150 kDa. Cross-linking of the 96-kDa CBP was found to occur spontaneously without UV light induction. Based on the ATP/Mg2+ requirements, the three CBPs can be subdivided into two classes: 1) ATP/Mg2+ independent (24- and 150 kDa) and 2) Mg2+ dependent (96 kDa). The co-purification of the 24- and 150-kDa CBPs through several different chromatographic steps is consistent with the existence of a yeast CBP complex, possibly analogous to mammalian eIF-4F.

Adenine Nucleotides↗
PubMed1981

Light requirement for induction and continuous accumulation of an ammonium-inducible NADP-specific glutamate dehydrogenase in chlorella.

The ammonium-inducible NADP-specific glutamate dehydrogenase of Chlorella sorokiniana was shown to require light for both its induction by ammonia in uninduced cells, and its continuous accumulation in fully induced cells. Addition of ammonia to uninduced cells in the light resulted in a 35-minute induction lag followed by linear and coincident increases in enzyme activity and antigen. Enzyme activity was not induced in the dark; however, transfer of these cells to the light resulted in an immediate increase in enzyme activity and antigen. The absence of an induction lag suggested that mRNA sequences and/or an enzyme precursor with different antigenic properties than the active holoenzyme accumulated in cells in the dark in ammonium medium. When fully induced cells were transferred to the dark, the activity of the enzyme quickly ceased to accumulate. In contrast to the NADP-specific isozyme, the cells also contain a constitutive NAD-specific isozyme which was shown to accumulate in cells in the dark in either ammonium or nitrate medium.

Journal Article↗
PubMed1995

Diphosphoryl lipid A from Rhodobacter sphaeroides transiently activates NF-kappa B but inhibits lipopolysaccharide induction of kappa light chain and Oct-2 in the B-cell lymphoma line 70Z/3.

Lipopolysaccharide (LPS) is implicated in much of the pathophysiology associated with gram-negative septic shock. One approach to this serious clinical problem is to develop new drugs that antagonize the action of toxic LPS. A model system to study LPS action and test for potential antagonists is readily provided by LPS regulation of the kappa gene in the murine B-cell line 70Z/3. Rhodobacter sphaeroides diphosphoryl lipid A (RsDPLA) effectively blocked toxic LPS induction of kappa light-chain immunoglobulin expression in 70Z/3 cells. Induction of kappa expression by LPS is dependent on the activation of at least two transcription factors, Oct-2 and NF-kappa B. RsDPLA completely repressed the long-term activation of NF-kappa B observed after 24 h of Salmonella typhosa LPS treatment and antagonized activation of oct-2 mRNA expression. However, RsDPLA was not an inert competitor of LPS. RsDPLA alone strongly activated NF-kappa B binding activity by 30 min but not beyond 9 h of treatment. It also induced a small increase in oct-2 mRNA levels. RsDPLA is not simply a weak agonist; we found no graded increase in kappa expression with increasing RsDPLA concentrations up to 50 micrograms/ml. The NF-kappa B complexes activated by RsDPLA and S. typhosa LPS were both composed of the p50-p65 heterodimer. These results suggest that the physiological LPS receptor(s) on B cells transmits qualitatively different signals depending on the nature of the binding ligand and that the fatty acyl groups of LPS play an important role in activating signal transduction.

Animals↗
PubMed1979

Inhibition by trioxalen (psoralen) plus near-ultraviolet light of the induction of ornithine decarboxylase in Chinese-hamster cells.

Trioxalen (trimethylpsoralen) plus near-u.v. light, a potent inhibitor of DNA and RNA synthesis, inhibits the induction of ornithine decarboxylase in stationary-phase V79 fibroblasts. It does not affect the translation of pre-existing mRNA. The method, in view of its high degree of specificity and precise timing, is a better choice for inhibiting RNA synthesis than the commonly used chemical inhibitors and precursor analogues.

Animals↗
PubMed1993

Circadian and light-regulated expression of nitrate reductase in Arabidopsis.

The expression of a number of plant genes is regulated by an endogenous circadian clock. We report that the Arabidopsis NIA2 (nitrate reductase) gene shows robust circadian oscillations in mRNA accumulation which persist for at least 5 days in plants that have been grown in a light-dark (LD) cycle and then transformed to continuous light (LL). We further show that NIA2 mRNA accumulation oscillates in a circadian fashion in plants that have been grown in LD and then transferred to continuous darkness (DD). Results from nuclear run-on transcriptional analysis suggest that the oscillations in steady-state levels of NIA2 mRNA abundance are not primarily due to changes in transcription but, instead, reflect post-transcriptional regulation. The circadian oscillations in NIA2 mRNA abundance are paralleled by circadian oscillations in nitrate reductase enzyme activity (NR activity) in Arabidopsis plants that have been grown in LD and then transferred either to DD or to LL. Etiolated Arabidopsis seedlings express neither NIA2 mRNA nor NR activity. However, both NIA2 mRNA accumulation and NR activity are induced by exposure to white light. The inductive effects of light on NIA2 mRNA accumulation are due, at least in part, to a very low fluence phytochrome-mediated response. However, the persistence of circadian oscillations in NIA2 mRNA abundance for at least 5 days in LL demonstrates that the circadian clock is capable of overriding or gating the inductive effects of light on NIA2 mRNA accumulation in Arabidopsis for an extended, continuous period of time.

Arabidopsis↗
PubMed2002

Independent induction of two blue light-dependent monovalent anion transport systems in the plasma membrane of Monoraphidium braunii.

In the plasma membrane of the green alga Monoraphidium braunii there are at least two monovalent anion transport systems. One of them is specific for bicarbonate. This transport system is activated by blue light and its induction is triggered by a decrease in the external CO2 concentration. The second transport system is responsible for nitrate uptake at least. This transport system is also activated by blue light and its induction occurs when there is no ammonium in the external medium. Both transport systems are synthesized independently. Hence, when M. braunii cells grow with nitrate as the only nitrogen source under high CO2, they have a nitrate transport system but lack a bicarbonate transporter. Conversely, cells grown with ammonium under low CO2, have a bicarbonate transport system but lack a nitrate transporter. Both transport systems are induced in cells irradiated with white light in the absence of a carbon source, suggesting that there may be precursors in the plasma membrane that only need the synthesis and assembly of some component(s) to become fully active. The induction of nitrate and nitrite reductases, however, only takes place when a carbon source is supplied to the cells.

Anion Transport Proteins↗
PubMed1985

Photoreactivation of Escherichia coli reverses umuC induction by UV light.

UV mutagenesis in Escherichia coli depends on the presence of a premutagenic lesion in DNA and on the induction of the umuCD gene product as part of the SOS response. Using operon fusions between the E. coli lacZ gene and the SOS genes umuC, uvrB, and dinD, we have affirmed the expected role of the cyclobutane pyrimidine dimer in inducing SOS gene transcription. In addition, we found that photoreactivation of cyclobutane pyrimidine dimers reversed umuC induction to the same extent as it reversed mutagenesis. Therefore, the photoreactivability of UV mutagenesis does not itself identify the cyclobutane pyrimidine dimer as the UV mutagenic lesion in E. coli.

Bacterial Proteins↗
PubMed1998

Interaction of nickel with UV-light in the induction of cytogenetic effects in human peripheral lymphocytes.

Chemical interaction is of major concern in the assessment of risk by regulatory agencies. In the present study, treatment of human lymphocytes with NiSO4 (1-100 microM) or UV-light (200, 1000 ergs/mm2) induced micronuclei (MN) in a dose-dependent fashion. Statistical analysis of the interaction factor (IF), showed that combined treatments of Ni(II) (1-100 microM) with UV-light (200, or 1000 ergs/mm2) interacted antagonistically for the induction of MN. Recently we reported that Ni(II) (0.5-10 microM) with UV-light (200 or 1000 ergs/mm2) or Cr(VI) or X-rays interacted antagonistically for the induction of sister chromatid exchanges (SCE), in peripheral human lymphocytes. These observations suggest that nickel present in complex mixtures may reduce the response, even in the presence of strong MN or SCE inducers, and may lead, therefore, to an underestimate of chemical exposure as assessed by these assays. Furthermore, metals affecting certain microsteps in the process of DNA replication or repair (e.g., histones, polymerases, ligases) may have similar antagonistic effects. Further studies are therefore recommended.

Dose-Response Relationship, Drug↗