Involvement in DNA repair of the ruvA gene of Escherichia coli

Summary The ruv operon of Escherichia coli consists of two genes, orfl1 and ruv, which encode 22 and 37 kilodalton proteins, respectively, and are regulated by the SOS system. Although the distal gene, ruv, is known to be involved in DNA repair, the function of orf1 has not been studied. To examine whether orf1 is also involved in DNA repair, we constructed a strain with a deletion of the entire ruv operon. The strain was sensitive to UV even after introduction of low copy number plasmids carrying either orf1 or ruv, but UV resistance was restored by introduction of a plasmid carrying both orfl and ruv. These results suggest that orf1 as well as ruv is involved in DNA repair. Therefore, orf1 and ruv should be renamed ruvA and ruvB, respectively.     

Neuropeptide gene expression and neural activity: Assessing a working hypothesis in nucleus caudalis and dorsal horn neurons expressing preproenkephalin and preprodynorphin

1. The working hypothesis that neuropeptide gene expression in a neuron is an indicator of that neuron's physiological activity is discussed. 2. Representative examples from the literature are presented to support the hypothesis. 3. Further, we discuss the regulation of expression of two opioid peptides, preproenkephalin and preprodynorphin, in laminae I and II of the spinal cord and in nucleus caudalis of the trigeminal nuclear complex, where they may play a role in pain modulation. 4. The expression of the opioid peptide genes can be induced by both painful and nonnoxious stimuli in neurons in time-dependent and sensory-specific fashions.     

Stimulation of the Uptake of Sorbitol into Vacuoles from Apple Fruit Flesh by Abscisic Add and into Protoplasts by Indoleacetic Acid

The uptake of sorbitol into vacuoles from immature flesh ofapple fruit (Maluspumila Mill, var domestica Schneid.) was facilitatedby 10^–6 M ABA, while such uptake into protoplasts wasnot stimulated. By contrast, the application of 10^–5 MIAA facilitated uptake of sorbitol into protoplasts but didnot significantly into vacuoles. (Received July 17, 1990; Accepted December 25, 1990)     

Sensitive detection of viral antigens with a new method, "laser magnet immunoassay".

A new method, "laser magnet immunoassay" (LMIA), has been developed for sensitive detection of viral antigens. Target viruses captured on microbeads were made to react with antibodies labeled with magnetite particles. In a magnetic field, magnetically labeled antigens dispersed in water were attracted to and concentrated at one point on the surface, resulting in the lifting up of a small surface area. A laser beam which was incident on the point reflected, making an interference fringe. The intensity of the fringe indicates the amount of the magnetite conjugated with antigen. A very low concentration of antigens, such as 5 particles of influenza virus and 0.1 pg/ml of human immunodeficiency virus (HIV) p24 antigen in human serum, could be detected by this method. Application of this method to diagnoses of viral diseases in early stages is discussed.     

Chemiluminescence in L-tyrosine-H2O2-horseradish peroxidase system: possible formation of tyrosine cation radical

Tyrosine-H2O2-horseradish peroxidase system at pH 7.4 emitted light in visible region. Phenolic compounds other than tyrosine were also emissive, whereas methoxy phenylalanine and phenyl compounds were not, in H2O2-peroxidase systems. Chemiluminescence spectrum of tyrosine of tyrosine-H2O2-horseradish peroxidase system showed two prominent peaks at 478 nm and 500 nm (Luminescence 1) and additional two or three peaks near 550 and 610 nm (Luminescence 2). Luminescence 1 is quite similar to the phosphorescence originated from an excited tyrosine in triplet state, while Luminescence 2 is quite similar to the phosphorescence originated from an indole in triplet state. Possible formation of tyrosine cation radical (a precursor of the excited tyrosine) and indole cation radical in the enzyme protein (a precursor of the excited tryptophan residue) were discussed.     

Immunohistochemical studies of the serotonergic supraependymal plexus in the mammalian ventricular system, with special reference to the characteristic reticular ramification

Distributional and morphological features, especially characteristics of the ramification of serotonin-containing supraependymal fibers (SEF), were studied in the ventricular systems of mammals (mouse, rat, guinea pig, rabbit, cat, dog, monkey) by means of a modified peroxidase antiperoxidase technique, using antiserotonin antiserum prepared in our laboratory. SEF were present in all ventricular systems, except on the third ventricle floor and in the choroid plexus. The density of SEF was higher in the smaller species. In the rat, light- and scanning electron microscopical SEF were almost completely abolished 1 week after intraventricular administration of 5,6-dihydroxytryptamine. Ramification of SEF was complicated; the SEF formed a true network with frequent anastomosing. In the ventricular system of rats rendered hydrocephalic by kaolin administration, the mode of axonal branching in the supraependymal plexus could best be analyzed by the scanning electron microscope because the meshes of the plexus were spread out.     

Cloning of the Escherichia coli gene for the stringent starvation protein

Summary In order to clone the Escherichia coli gene for the stringent starvation protein (SSP), we determined its N-terminal sequence as well as the sequence of two peptide fragments obtained by cyanogen bromide cleavage of the protein. We then chemically synthesized four sets of oligodeoxyribonucleotide mixtures that represented possible codon combinations for parts of these amino acid sequences. The synthetic oligonucleotides were labelled with ³²P at their 5-termini and used as hybridization probes to detect DNA fragments containing the complementary sequences. Genomic Southern hybridization of E. coli chromosomal DNA gave up to ten DNA fragments hybridizing with each probe but only a few hybridized with two or more of the probes. The latter fragments were coloned in pBR322. By determining partial base sequences with a rapid method and examining proteins encoded by the DNA fragments, we were able to show that we had isolated a clone containing the complete SSP structural gene.Abbreviations SSP stringent starvation protein - PTH phenylthiohydantoin     

Clostridium ramosum, an IgA protease-producing species and its ecology in the human intestinal tract

A bacterial strain isolated from feces of a patient with ulcerative colitis, which had been shown to produce a novel immunoglobulin A (IgA) protease (cleaving both the human IgA1 subclass and IgA2 subclass of A2m(1) allotype) extracellularly, was identified as Clostridium ramosum. By using a selective medium (propionate-rifampicin-gentamicin-colimycin-polymyxin medium) devised for C. ramosum, analysis of the population level of this organism was performed to determine its ecology in the human intestinal tract. C. ramosum was isolated in 20 of 25 fecal samples (80%) from patients with inflammatory bowel disease (I.B.D.) and in 112 of 135 samples (83%) from patients without I.B.D. (control group). C. ramosum was also isolated from 6 of 11 biopsy samples (55%) of the inflamed rectal mucosa from patients with ulcerative colitis and from five of 15 samples (33%) from the intact mucosa of the control group. The population levels of C. ramosum in most of the biopsy samples ranged from 2.3 to 5.0 log10 per gram. The IgA protease-positive C. ramosum was found in only four of 135 fecal samples (3%) and one of 15 biopsy samples (6.7%) from the control group. These results indicate that IgA protease-positive C. ramosum is not likely to play a role in the induction of I.B.D., unless the organism is first isolated from the patient with I.B.D.     

Oxidized and reduced nicotinamide adenine dinucleotide phosphate levels of plants hardened and unhardened against chilling injury

Pea plants (Pisum sativum L. var. Alaska) subjected to low temperature (5°) in the light acquired resistance against chilling injury.

Unhardened plants maintained high NADP and low NADPH levels during illumination at 25° but hardened plants had low NADP and high NADPH levels in the light. When the unhardened plants were transferred to the dark room at 25°, their NADPH levels decreased immediately. On the other hand, hardened plants maintained a high NADPH level for a few hours even in the dark.