Effect of metal ions on the adaptive response induced by N-methyl-N-nitrosourea in Escherichia coli

Induction of the adaptive response was quantified by analysis of beta-galactosidase released after the treatment of Escherichia coli CHS26/pYM3 (ada'-lacZ') with N-methyl-N-nitrosourea (MNU). Of the 15 metal ions examined, only Cd++ and Hg++ inhibited induction of the adaptive response with neither severe suppression of cell growth nor inhibition of the induction of the SOS response by MNU. Mutagenicity of MNU was potentiated by the presence of these metal ions in an E. coli strain. These results suggest that the inhibition mechanism involves a specific interaction of Cd++ or Hg++ with O6-methyl-guanine-DNA methyltransferase.     

Participation of microsomal aldehyde reductase in long-chain fatty alcohol synthesis in the rat brain

The participation of microsomal aldehyde reductase in long-chain fatty alcohol synthesis in the rat brain was examined. A reaction mixture of [1-14C]hexadecanoic acid with brain microsomes and NADPH formed two radioactive products having the same mobilities as pure hexadecanal (RF 0.61) and hexadecanol (RF 0.22), respectively, on TLC plates. The product of the RF 0.61 spot was further identified as hexadecanal using gas-liquid chromatography after methylation and TLC of its reduced product with LiAlH4 and semicarbazide. The ratio of hexadecanal to hexadecanol varied from 0.4 to 1.2 under the present experimental conditions. When solubilized rat brain microsomes were applied to a Sepharose 4B column coupled with the rabbit antibody raised against rat liver microsomal NADPH-cytochrome-c reductase, which reacts with aldehyde reductase from rat brain, the eluted fraction ceased to form [14C]hexadecanol but continued to form [14C]hexadecanal from [14C]hexadecanoic acid. These results strongly indicate that hexadecanal is the intermediate in the synthesis of hexadecanol from hexadecanoic acid in rat brain microsomes with the participation of microsomal aldehyde reductase.     

Frequency domain studies of impedance characteristics of biological cells using micropipet technique. I. Erythrocyte.

This study aims at precise measurement of the membrane capacity and its frequency dependence of small biological cells using the micropipet technique. The use of AC fields as an input signal enables the magnitude and phase angle of membrane impedance to be measured at various frequencies. The micropipet technique was applied to human erythrocyte, and passive membrane capacity and conductivity were determined between 4 Hz and 10 KHz. Membrane capacity thus determined changed from 1.05 to 0.73 microF/cm2 between 4 Hz and 10 KHz. In addition to the micropipet technique, we used suspension method between 50 KHz and 10 MHz for the purpose of supplementing the new method with the one which has been in use for many years. We obtained a membrane capacity of 0.65-0.8 microF/cm2 using this technique. These values agree with the capacitance obtained with the micropipet method. Although this paper discusses only human erythrocytes, the study has been performed with lymphocytes and various forms of cancer cells. This paper is the first of the series of reports on frequency domain studies of the impedance characteristics of various biological cells.     

Acute reversible cataract due to nitrocompounds in Japanese quail (Coturnix coturnix japonica)

The present study was designed to examine the usefulness of the Japanese quail as an experimental model of cataractogenic activity. Chemicals, 2, 6-dibromo-4-nitro-phenol (2, 6-D), 2, 4-dinitroanisole (2, 4-DA), and 2, 4-dinitrophenol (2, 4-D; for the positive control), were administered singly through an oral route to 2-week old male Japanese quails to investigate the reversibility of cataracts. A single administration of 2, 4-D (36 and 43 mg/kg) produced reversible cataract in 14 of 16 animals (87.5%). This cataract was seen 1 or 2 hours after treatment and continued for 1 to 12 hours. Treatment with 2, 6-D (20 and 25 mg/kg) and 2, 4-DA (120 and 150 mg/kg) caused cataracts in 7 of 11 (63.6%) and 8 of 8 surviving animals (100%), respectively. Cataracts produced by 2, 6-D and 2, 4-DA, which were observed from 1 and 2 to 4 hours after the treatment, continued for 6 to 15 and 1 to 13 hours, respectively. Mortalities in the 25 mg/kg group of 2, 6-D, 120 mg/kg and 150 mg/kg group of 2, 4-DA were found in 2 of 5 animals, 1 of 5 animals and 5 of 9 animals, respectively. These results indicate that the Japanese quail is useful as an animal model to evaluate toxicity to the eye and cataractogenesis.     

Oxidation of lipids. XV. Role of hydrophilic diarylamines as antioxidants in the oxidations of lipids and biological tissues

The abilities of two kinds of water-soluble diarylamines, disodium 4-chloro-2,2'-iminodibenzoate (CCA) and disodium 4-chloro-3',6'-dimethyl-2,2'-iminodibenzoate (CCM), to protect lipids, membranes and biological tissues from oxidative damages have been studied. The experimental systems studied include the oxidations of methyl linoleate micelles and soybean phosphatidylcholine (Pc) liposomal membranes in aqueous dispersions, oxidative hemolysis of rabbit erythrocytes, and the in vivo oxidative damages of biological tissues all induced by free radicals generated from an azo radical initiator. The two diarylamines functioned as moderate chain-breaking antioxidants and retarded the above oxidations.     

Characterization of a glutathione conjugate of the 1,4-benzosemiquinone-free radical formed in rat hepatocytes

Rat hepatocytes treated with 1,4-benzoquinone formed 1,4-benzosemiquinone and 2-S-glutathionyl-1,4-benzosemiquinone radicals as detected by ESR spectroscopy. The 2-S-glutathionyl-1,4-benzosemiquinone radical was first obtained from the reaction of 1,4-benzoquinone with glutathione. Glutathione both reduced benzoquinone to form benzosemiquinone and conjugated benzoquinone to form 2-S-glutathionyl-1,4-benzosemiquinone radical. The ratio of these two radicals depended upon the ratio of 1,4-benzoquinone to glutathione. At near equimolar ratios, the 2-S-glutathionyl-1,4-benzosemiquinone radical was predominantly formed. This radical was characterized by computer simulation of the experimental spectra and identified by comparison of its hyperfine coupling constants with those of chemical analogues. The 2-S-glutathionyl-1,4-benzosemiquinone radicals formed inside hepatocytes, and then crossed the plasma membrane into the media.     

Analyses of constituents of feces and the effect of a vitamin B12 fortified diet on coprophagy in the mouse

In order to investigate coprophagy from the viewpoint of nutrition, fecal constituents were analyzed in freeze-dried samples. Feces were collected from 7:00 to 11:00 and from 19:00 to 23:00. Inorganic elements and crude fibers per unit weight were 3-4 times more concentrated in feces than in basal diet, whereas, crude proteins, crude fats and nitrogen-free extract showed various degrees of reduction. There were no differences in these tendencies with sampling time. As for some B vitamins, feces collected from 7:00 to 11:00 contained 22-92% more vitamins than feces collected from 19:00 to 23:00. In comparison with the dietary concentration, vitamin B12 was increased by 124-197 times (520-730 micrograms/100 g) in feces collected between 7:00 and 11:00. Folic acid in feces collected between 7:00 and 11:00 was 10 times greater than that in the diet. On the basis of the findings on vitamins, the effect of a vitamin B12 fortified diet (1,350 micrograms/100 g) on coprophagy was examined. Mean frequency of coprophagy per animal per day was 9.6 when animals were fed on the basal diet, whereas the frequency was immediately and significantly (p less than 0.05 approximately p less than 0.01) reduced to 4.7 after the diet had been replaced by the fortified one. However, coprophagy was not completely inhibited by vitamin B12 fortification. This indicates that some nutrient(s) in feces other than vitamin B12 might be of use to the host, and that otherwise, coprophagy might be a basically habitual form of behavior. Furthermore, under the fortified diet, the frequency of coprophagy increased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)     

Carbohydrate structures of acetylcholine receptor from Torpedo californica and distribution of oligosaccharides among the subunits

The structure of carbohydrates in acetylcholine receptor (AChR) from Torpedo californica is reported. Oligosaccharides released quantitatively from the whole molecule by N-oligosaccharide glycopeptidase digestion were fractionated by thin-layer chromatography and further purified by high-performance liquid chromatography. We show that more than 70% of the total oligosaccharide chains in Torpedo AChR are of the high-mannose type with the structures (Man)8(GlcNAc)2 and (Man)9(GlcNAc)2. The structure of these oligosaccharides were determined by proton nuclear magnetic resonance spectroscopy. These two types of oligosaccharides were shown to be distributed different proportions in all subunits of Torpedo AChR. We also show that several kinds of complex-type oligosaccharides comprising the rest of the carbohydrate in the protein exist mainly in the gamma and delta subunits. The structure of the carbohydrate moiety that is distributed on the four subunits of AChR was also examined by susceptibility to endo-beta-N-acetylglucosaminidase and sialidase and by binding affinity to lectins, e.g. concanavalin A, leucoagglutinating phytohemagglutinin, and wheat germ agglutinin.     

DNA fragments of 300 base pairs released from metaphase chromosomes by digestion with deoxyribonuclease I

DNase I digestion of metaphase chromosomes, that have been extensively digested with Hae III, further released chromosomal DNA and proteins; 3.3% and 10.8% of the chromosomal DNA and proteins, respectively, remained insoluble. However, digestion of chromosomes first with DNase I followed by Hae III caused most of the proteins to remain in the insoluble fraction. DNase I released DNA fragments of 300 base pairs long which were not released by Hae III digestion. These DNA fragments may be protected by protein components from further fragmentation by DNase I.     

Antibody responses to early antigens of varicella-zoster virus (VZV) during varicella and zoster

The antibody responses to membrane and early antigens and thymidine kinase of varicella-zoster virus (VZV) were studied in sera during both varicella and zoster by a test with fluorescent antibody to membrane antigen (FAMA), staining the biochemically transformed cells by the immunofluorescent technique and neutralization of virus-specific thymidine kinase activity, respectively. Similar increases in FAMA antibody titers were demonstrated in sera from patients with varicella and zoster. IgM was detected in both groups, but appeared earlier during varicella than during zoster. Furthermore, the antibody titers to early antigens and virus-specific thymidine kinase were higher in patients with zoster than in those with varicella. These data suggest that different types of antibody responses occur during varicella and zoster.