Effect of Atm disruption on spontaneously arising and radiation-induced deletion mutations in mouse liver

Deletion mutations were efficiently recovered in mouse liver after total-body irradiation with X rays by using a transgenic mouse "gpt-delta" system that harbored a lambda EG10 shuttle vector with the red and gam genes for Spi- (sensitive to P2 lysogen interference) selection. We incorporated this system into homozygous Atm-knockout mice as a model of the radiosensitive hereditary disease ataxia telangiectasia (AT). Lambda phages recovered from the livers of X-irradiated mice with the Atm+/+ genotype showed a dose-dependent increase in the Spi- mutant frequency up to sixfold at 50 Gy over the unirradiated control of 2.8x10(-6). The livers from Atm-/- mice yielded a virtually identical dose-response curve for X rays with a background fraction of 2.4x10(-6). Structural analyses revealed no significant difference in the proportion of -1 frameshifts and larger deletions between Atm+/+ and Atm-/- mice, although larger deletions prevailed in X-ray-induced Spi- mutants irrespective of Atm status. While a possible defect in DNA repair after irradiation has been strongly indicated in the literature for nondividing cultured cells in vitro from AT patients, the Atm disruption does not significantly affect radiation mutagenesis in the stationary mouse liver in vivo.     

Recombinant Pseudomonas putida carrying both the dsz and hcu genes can desulfurize dibenzothiophene in n-tetradecane

Pseudomonas putida IFO13696, a recombinant strain with dsz desulfurization genes, desulfurized dibenzothiophene (DBT) in water but not in n-tetradecane. By introducing into this recombinant strain the hcuABC genes that take part in the uptake of DBT in the oil phase into the cell, 82% of 1 mM DBT in n-tetradecane was degraded in 24 h by resting cells. The products of hcuABC genes thus acted in the uptake of DBT in n-tetradecane into the cells and were effective in desulfurization of DBT in the hydrocarbon phase.     

Selective cleavage of 10-methyl benzo[b]naphtho[2,1-d]thiophene by recombinant Mycobacterium sp. strain

Recombinant Mycobacterium sp. strain MR65 carrying dszABCD genes was used for desulfurization of 10-methylbenzo[b]naphtho[2,1-d]thiophene (10-methyl BNT) in the hexadecane phase. The specific activity was 25% of that of dibenzothiophene (DBT). One of two major metabolites of 10-methyl BNT produced by strain MR65 was identified as 1-methoxy-2-(3-methylphenyl)naphthalene by ¹H and ¹³C NMR. The other major metabolite and two minor metabolites were determined as 1-hydroxy-2-(3-methylphenyl)naphthalene, 2-(2-methoxy-3-methylphenyl)naphthalene and 2-(2-hydroxy-3-methylphenyl)naphthalene, respectively, by HPLC and GC-MS. The production ratio of the two desulfurization metabolite isomers was 0.99:0.01, calculated on the basis of peak GC areas. These results indicated that the C-S bond adjacent to the naphthalene skeleton was selectively cleaved to form the two major compounds.     

Association between plasma zinc concentration and zinc kinetic parameters in premenopausal women

The objective of this study was to measure relationships between plasma zinc (Zn) concentrations and Zn kinetic parameters and to measure relationships of Zn status with taste acuity, food frequency, and hair Zn in humans. The subjects were 33 premenopausal women not taking oral contraceptives and dietary supplements containing iron and Zn. Main outcomes were plasma Zn concentrations, Zn kinetic parameters based on the three-compartment mammillary model using 67Zn as a tracer, electrical taste detection thresholds, and food frequencies. Lower plasma Zn was significantly (P < 0.01) associated with smaller sizes of the central and the lesser peripheral Zn pools, faster disappearance of tracer from plasma, and higher transfer rate constants from the lesser peripheral pool to the central pool and from the central pool to the greater peripheral pool. The break points in the plasma Zn-Zn kinetics relationship were found between 9.94 and 11.5 micromol/l plasma Zn. Smaller size of the lesser peripheral pool was associated with lower frequency of beef consumption and higher frequency of bran breakfast cereal consumption. Hypozincemic women with plasma Zn <10.7 micromol/l or 700 ng/ml had decreased thresholds of electrical stimulation for gustatory nerves. Our results based on Zn kinetics support the conventional cutoff value of plasma Zn (10.7 micromol/l or 700 ng/ml) between normal and low Zn status.     

Mouse circadian rhythm before the Kobe earthquake in 1995

Mouse circadian diagrams recorded at Osaka University showed unusual mouse behavior before the Kobe earthquake on January 17th, 1995. The locomotive activities on January 16th showed drastic increases, several times above the standard deviation, during both sleep and active periods, indicating that mice perceived of some preseismic signals.     

Effect of dietary fiber on the lipid metabolism and immune function of aged Sprague-Dawley rats

Eight-month-old Sprague-Dawley rats were fed on diets containing dietary fiber at the 5% level for 3 weeks to examine the effect on the lipid metabolism and immune function. Among cellulose, guar gum, partially hydrolyzed guar gum (PHGG), glucomannan and highly methoxylated pectin, guar gum induced a significant decrease in the food intake and weight gain, as well as a significant increase in the liver weight. In addition, the epidydimal adipose tissue weight of the rats fed on PHGG was significantly higher than that of the rats fed on cellulose. There was no significant effect on the serum lipid levels, but the serum IgG level of the rats fed on guar gum was significantly lower than that of the rats fed on cellulose. The IgA and IgG productivity in mesenteric lymph node (MLN) lymphocytes was significantly higher in the rats fed on guar gum, glucomannan and pectin than in those fed on cellulose, while the effect on Ig productivity in spleen lymphocytes was not as marked. In addition, only guar gum induced a significant increase of IgM productivity in MLN lymphocytes when compared to the cellulose group. These results suggest that enhancement of the immune function by dietary fiber is mainly expressed in the gut immune system.     

Shoot population dynamics of persisting clones of<Emphasis Type="Italic"> Miscanthus sinensis</Emphasis> in the warm-temperate region of Japan

The population dynamics of annual shoots in four clonal patches of Miscanthus sinensis was surveyed in terms of clone persistence. Over a study period of 3 years, a stable net shoot number was attained through a balanced replacement of old shoots by tillering 2–3 times a year. The birth rate was significantly correlated with the average monthly temperature. This suggests that a warm climate advances the date of tillerings, and shoots become taller as they emerge earlier. Five cohorts were identified, corresponding to shoots that were born in spring, early summer, summer, autumn and early winter. The autumn cohorts were more numerous and had a greater longevity than the other cohorts; they were thus were best suited for overwintering and, consequently, maintaining the population from one generation to the next. The shoots of earlier cohorts grew too tall to survive the cold of winter, which might cause freezing injury, while later cohorts shoots excelled in overwintering because of their shortness. However, if the delayed shoots are very short, they will also have difficulty in surviving the early season of growth. Therefore, M. sinensis shoots have an optimum size for survival.     

Purification and characterization of α-D-galactosidase produced by ADG cell line established from abalon digestive gland

ADG cell line was established from an abalonedigestive gland and previously characterized. ADGcells have the potential to grow in protein-freeculture and secrete l3 types of glycosidases. Inthis article, we determined the origin of ADG cell line,using electron microscopy, and purified a glycosidasesecreted by these cells. The electron microscopicanalysis showed that ADG cell line contains severalnuclei, which suggests that they may be derived fromprotist cells. Moreover, -D-galactosidasethat hydrolyzes p-nitorophenyl galactopyranosidewas purified 130-fold from the spent culture medium ofADG cells. The molecular weight of the enzyme,determined by sodium dodecyl sulfate polyacrylamidegel electrophoresis and gel filtration analysis, wasshown to be 43 and 42 kDa, respectively, and itappeared to consist of a single polypeptide chain. The purified enzyme preparation was practically freefrom other glycosidases secreted from the cells. Catalytic activity was optimal at pH 5.5 and at atemperature of 37 °C. The enzyme was also the most stable at pH 5.5.