Effect of Ammonia on Cellular pH of Anabaena cylindrica Determined with 31P NMR Spectroscopy

The pH changes in the blue-green alga (cyanobacterium) Anabaenacylindrica caused by addition of ammonia were investigated using³¹P NMR spectroscopy. A pH shift of 0.9 or more was observedwhen 30 nM NH₄OH was added to the cell suspension, but no significantcellular pH change was observed with 50 mM NH₄CI, a concentrationhigh enough to stimulate dark CO₂ fixation of this alga. Thechange in cellular pH does not seem to cause ammonia-inducedstimulation of dark CO₂ fixation. (Received June 22, 1985; Accepted January 10, 1986)     

Molecular cloning of the uvrD gene of Escherichia coli that controls ultraviolet sensitivity and spontaneous mutation frequency

Summary The uvrD gene of Escherichia coli that control UV sensitivity and spontaneous mutation frequency has been cloned with phage as vector. The increased sensitivity to ultraviolet light (UV) of uvrD3, uvrE502, recL152, and pdeB41 mutants, high mutability of uvrD3 and pdeB41 mutants, and conditional lethality of strain TS41 that carried pdeB41, polA1, and sup126 mutations were all suppressed by lysogenization of the mutant cells with uvrD ⁺. These results were consistent with the idea that the uvrD, uvrE, recL, and pdeB mutations are alleles of the uvrD gene. In addition to the uvD gene, uvrD ⁺ carried the corA gene that controls transport of Mg⁺⁺, Mn⁺⁺, and Co⁺⁺ through the cell membrane. Hybrid plasmids carrying both uvrD and corA genes were also constructed by using pKY2289 as a cloning vehicle. Orientational isomers that carried the same 12.0 kb fragment in the opposite direction were equally efficient in complementing the UvrD^- as well as CorA^- defects of the transformed host cells, suggesting that the DNA insert contains all the genetic signals needed to express the two gene products. Insertion of the sequence into recombinant plasmids was performed to generate appropriate restriction endonuclease target sites in the cloned DNA fragments.     

Infection of Actinomycin-Permeable Mutants of Escherichia coli with Urea-Disrupted Bacteriophage

Intact cells of actinomycin-permeable mutants of Escherichia coli could be infected with urea-disrupted phage T4 (designated as T4pi). The parental strains and the revertants, which are impermeable to actinomycin, were not susceptible to T4pi unless they had been treated with agents which altered their permeability. The permeable mutants developed competence for pi infection during the growth cycle; cells in the early stationary phase produced 10- to 100-fold more plaques on plating with T4pi than did exponentially growing cells. Colistin (polymyxin E) was effective in converting noncompetent cells of either permeable or nonpermeable strains to the competent state. Treatment with lysozyme resulted in a considerable increase in susceptibility to T4pi of permeable mutants but not of nonpermeable cells. It appears that development of competence for pi infection is mainly due to alterations in the permeability barriers of the cell.     

Genotoxicity and cell proliferative activity of omeprazole in rat stomach mucosa.

Induction of unscheduled DNA synthesis (UDS) as a marker of genotoxicity and induction of ornithine decarboxylase (ODC) activity as a marker of cell proliferative activity by omeprazole were determined in the glandular stomach mucosa of male F344 rats after oral administration. Commercial enteric-coated omeprazole (Losec) at doses of 30 and 100 mg/kg body weight induced a dose-dependent increase in UDS but not replicative DNA synthesis in the pyloric mucosa of rat stomach 4 h after its administration. Dose-dependent significant induction of ODC activity was observed in fundic and pyloric mucosa with a maximum 8 h after administration of omeprazole at doses of 37.5-100 mg/kg body weight. These results show that omeprazole has genotoxicity and cell proliferative activity in the rat glandular stomach mucosa.     

RNase H-defective mutants of Escherichia coli: a possible discriminatory role of RNase H in initiation of DNA replication

Summary Mutants of Escherichia coli completely deficient in RNase H activity were isolated by inserting transposon Tn3 into the structural gene for RNase H, rnh, and its promoter. These rnh ^- mutants exhibited the following phenotypes; (1) the mutants grew fairly normally, (2) rnh ^- cells could be transformed with ColE1 derivative plasmids, pBR322 and pML21, though the plasmids were relatively unstable, under non selective conditions, (3) rnh ^- mutations partially suppressed the temperature-sensitive phenotype of plasmid pSC301, a DNA replication initiation mutant derived from pSC101, (4) rnh ^- mutations suppressed the temperature-sensitive growth character of dnaA ^ts mutant, (5) rnh ^- cells showed continued DNA synthesis in the presence of chloramphenicol (stable DNA replication). Based on these findings we propose a model for a role of RNase H in the initiation of chromosomal DNA replication. We suggest that two types of RNA primers for initiation of DNA replication are synthesized in a dnaA/oriC-dependent and-independent manner and that only the dnaA/oriC-dependent primer is involved in the normal DNA replication since the dnaA/oriC independent primer is selectively degraded by RNase H.Abbreviations AP^r ampicillin-resistant - kb kilobase pair(s) - NEM N-ethyl maleimide - Ts temperature-sensitive     

Heterotypic induction of stomach-like glands in the urogenital sinus endoderm under the influence of stomach mesenchyme of foetal rats

Summary Urogenital sinus endoderm of 16.5-day rat foetuses was combined with stomach mesenchyme and the recombinants were either treated with testosterone and grown in vitro or cultured beneath the kidney capsule of adult male rats of the same strain. It was found that testosterone stimulated mitosis in the urogenital endoderm. In recombinants grown under the kidney capsule a stratified squamous epithelium and stomach-like glands were induced under the influence of the forestomach and glandular stomach mesenchymes. However, the induced glands expressed neither rat pepsinogen nor rat ventral prostatic antigen. They did not produce mRNA for the prostatic steroid-binding protein C1. Thus, stomach mesenchyme of rat foetuses induces organ-specific morphogenesis but not functional differentiation in the heterologous endoderm, indicating that cytodifferentiation does not always accompany morphogenesis.     

Produced by a Strain of Unidentified Actinomycetes sp.

The possibility of using two kinds of sorghum as raw materials in consolidated bioprocessing bioethanol production using Flammulina velutipes was investigated. Enzymatic saccharification of sweet sorghum was not as high as in brown mid-rib (bmr) mutated sorghum, but the amount of ethanol production was higher. Ethanol production from bmr mutated sorghum significantly increased when saccharification enzymes were added to the culture.     

Association of insomnia symptoms and non-restorative sleep with Typus melancholicus: a Japanese general population survey

Sleep and Biological Rhythms - This study aimed to investigate the association between insomnia symptoms and non-restorative sleep (NRS) in individuals with Typus melancholicus, a personality trait...     

Enzyme Kinetics of an Alternative Splicing Isoform of Mitochondrial 8‐Oxoguanine DNA Glycosylase,OGG1‐1b,and Compared with the Nuclear OGG1‐1a

Eight alternatively spliced isoforms of human 8‐oxoguanine DNA glycosylase (OGG1) (OGG1‐1a to ‐1c and ‐2a to ‐2e) are registered in the National Center for Biotechnology Information. OGG1(s) in mitochondria have not yet been fully characterized biochemically. In this study, we purified mitochondrial recombinant OGG1‐1b protein and compared its activity with nuclear OGG1‐1a protein. The reaction rate constant (k_g) of the 7,8‐dihydro‐8‐oxoguanine (8‐oxoG) glycosylase activity of OGG1‐1b was 8‐oxoG:C >> 8‐oxoG:T >> 8‐oxoG:G > 8‐oxoG:A (7.96, 0.805, 0.070, and 0.015 min^?1, respectively) and that of the N‐glycosylase/DNA lyase activity (k_gl) of OGG1‐1b was 8‐oxoG:C > 8‐oxoG:T ?8‐oxoG:G >> 8‐oxoG:A (0.286, 0.079, 0.040, and negligible min^?1, respectively). These reaction rate constants were similar to those of OGG1‐1a except for k_gl against 8‐oxoG:A. APEX nuclease 1 was required to promote DNA strand breakage by OGG1‐1b. These results suggest that OGG1‐1b is associated with 8‐oxoG cleavage in human mitochondria and that the mechanism of this repair is similar to that of nuclear OGG1‐1a.