Refeeding with a standard diet after a 48-h fast elicits an inflammatory response in the mouse liver

Unhealthy eating behaviors increase the risk of metabolic diseases, but the underlying mechanisms are not fully elucidated. Because inflammation contributes to the pathogenesis of metabolic diseases, it is important to understand the effects of unhealthy eating on the inflammatory state. The objective of our present study was to address the effects of a fasting–refeeding regime, a model of irregular eating, on the hepatic inflammatory responses in mouse. The animals were fasted for 48 h and then refed either a standard or low-carbohydrate/high-fat diet. Inflammatory gene expression in the liver was then sequentially measured for the first 17 h after initiation of refeeding. To assess the roles of dietary carbohydrates and toll-like receptor 2 (TLR2) in the refeeding-induced inflammatory changes, gene expression levels in mice refed only carbohydrates (α-corn starch and sucrose) at different doses and in TLR2-deficient mice refed a standard diet were also analyzed. Refeeding with a standard diet increased the liver expression of Tlr2, proinflammatory mediators (Cxcl10, Cxcl1, Cxcl2, Icam-1) and negative regulators of TLR-signaling (A20 and Atf3). These increases were attenuated in mice refed a low-carbohydrate/high-fat diet. Refeeding only α-corn starch and sucrose also increased the expression of these inflammatory pathway genes depending on the doses. TLR2 deficiency significantly attenuated the refeeding-induced increase in the liver expression of Cxcl10, Cxcl1, Icam-1 and A20. These findings suggest that an irregular eating behavior can elicit a liver inflammatory response, which is at least partly mediated by TLR2, and that dietary carbohydrates play critical roles in this process.     

Interactions of bacterial flagellar chaperone–substrate complexes with FlhA contribute to co‐ordinating assembly of the flagellar filament

Assembly of the bacterial flagellar filament is strictly sequential; the junction proteins, FlgK and FlgL, are assembled at the distal end of the hook prior to the FliD cap, which supports assembly of as many as 30 000 FliC molecules into the filament. Export of these proteins requires assistance of flagellar chaperones: FlgN for FlgK and FlgL, FliT for FliD and FliS for FliC. The C‐terminal cytoplasmic domain of FlhA (FlhA_C), a membrane component of the export apparatus, provides a binding‐site for these chaperone–substrate complexes but it remains unknown how it co‐ordinates flagellar protein export. Here, we report that the highly conserved hydrophobic dimple of FlhA_C is involved in the export of FlgK, FlgL, FliD and FliC but not in proteins responsible for the structure and assembly of the hook, and that the binding affinity of FlhA_C for the FlgN/FlgK complex is slightly higher than that for the FliT/FliD complex and about 14‐fold higher than that for the FliS/FliC complex, leading to the proposal that the different binding affinities of FlhA_C for these chaperone/substrate complexes may confer an advantage for the efficient formation of the junction and cap structures at the tip of the hook prior to filament formation.     

Partial Purification and Some Properties of Mitomycin C Inactivating Factors of Pseudomonas convexa 4–87

Strains producing higher levels of cellulolytic enzymes were selected from among 520 strains of plant pathogenic fungi, Fusarium species, and F. oxysporum strain SUF850 was found to be the best producer. When strain SUF850 was cultured using one of three polysaccharides, Avicel, carboxy- methyl cellulose (CMC) or xylan, as a carbon source, the culture filtrate contained degrading activi- ties toward all three substrates, i.e., irrespective of the carbon source used. From the culture filtrate of Avicel-grown cells, four distinct enzymes were purified to homogeneity, as judged on SDS-PAGE. They were designated as CMCase I, CMCase II, /Miitrophenyl-β-d-cellobiosidase and xylanase, and the characteristics of the individual enzymes were examined and compared.     

Effect of Rifampicin and Uracil Depletion on Bacteriophage ϕX174 DNA Synthesis in an E. coli dnaHts Mutant

The fluorescent antibody technique was used to trace an inoculated Nocardia erythropolis strain which was capable of rapidly degrading phthalate esters in soil column and activated sludge systems. The reaction of antibody to Nocardia erythropolis S-1 was highly strain specific, i. e., only one of twelve other strain of N. erythropolis was stained with this fluorescent antibody. All other species of Nocardia and other genera of bacteria and a strain of Candida were not stained. Using this technique it was demonstrated that N. erythropolis S-1 inoculated into activated sludge and soil column systems was successfully distinguished from many other microorganisms in mixed culture systems, and the distribution of this strain was appreciated.     

Mechanism of Action of Bacillus thuringiensis Insecticidal Delta-endotoxin on Insect Cells in Vitro

Cultured insect cells, TN-368 from the cabbage looper, swelled and burst upon treatment with the enzyme-digested delta-endotoxin of Bacillus thuringiensis var. aizawai. The cytotoxic sweelling was depended upon the amount of the delta-endotoxin added and the concentration of NaCl or KC1 in the isotonic solution. The concentration of Na⁺ in the swollen cells approximately doubled in isotonic NaCl, while that of K⁺ decreased to 10% of the original cellular concentration. The cell swelling was inhibited by tetrodotoxin and also by ouabain in only KC1 isotonic solution. On the other hand, 4-aminopyridine stimulated the swelling in the isotonic KC1 solution, These results indicate that the delta-endotoxin induces the stimulation of Na+ influx and K+ efflux in the isotonic NaCl solution, and also stimulates the Na⁺, K⁺-ATPase in the isotonic KC1 solution. The cytotoxic swelling was also blocked by cAMP, AMP, ATP, GTP, and NAD, but not by adenosine and GMP. These results suggest the participation of nucleotide derivatives in the action of delta-endotoxin.     

Effect of Chloramphenicol on the DNA Synthesis of Bacteriophage ϕX174

In bacteriophage ?X174 infection, the net synthesis of replicative form DNA ceased between 15 and 20 min after infection. When 30 μg of chloramphenicol/ml was added, net RF synthesis, however, continued beyond the normal time and level of turn-off. Experiments with ?X174 mutants unable to synthesize single-stranded DNA showed that a protein synthesis was required for the cessation of net RF synthesis and the protein was synthesized between 10 and 15 min after infection.     

Reductive Dechlorination of 1,2,4-Trichlorobenzene by Staphylococcus epidermidis Isolated from Intestinal Contents of Rats

Twelve bacterial strains which were concerned with dechlorination of 1,2,4-trichlorobenzene (TCB) were isolated from the intestinal contents of rats and it was found that they belonged to Staphylococcus epidermidis (strain A-F), Staphylococcus saprophyticus (strain G), Streptococcus sp. (strains H and I), Bacillus sp. (strain J), Gram negative rod (strain K) and Lactobacillus sp. (strain L).

In Staphylococcus epidermidis (Strain A), TCB was mainly converted to o-dichlorobenzene and the latter was preferentially converted to monochlorobenzene (MCB) among dichlorobenzenes (DCBs). These conversions proceeded only under a gas phase of hydrogen. Furthermore, dry and broken cells of intact bacteria also maintained the dechlorinating activities, which were stimulated by the addition of NADPH.

Therefore, it was supposed that the conversion of TCB to MCB via DCBs was reductively carried out by enzymes originating from the isolated bacteria.     

Characteristic Decrease of Nuclear Protein Kinase Activity in G1-Arrested Cells of Saccharomyces cerevisiae cdc28

An alkalopsychrotrophic strain, Micrococcus sp. 207, inducibly and extracellularly produced amylase and pullulanase. The main hydrolysis product from amylose, with a crude enzyme preparation, was maltotetraose. The optimum temperature for activity of the amylase was 60°C and that for pullulanase 55°C. The activities at 0 to 30°C exhibited similar activation energy values. In an optimized production medium at pH 9.7, the highest yields of these enzymes were obtained after cell growth at 18°C for 4 days. At pH 8.5, the yields of amylase and pullulanase became maximum after 3 days cultivation. With more prolonged cultivation, the yield of amylase but not that of pullulanase activity decreased. These enzymes were not produced at temperatures above 30°C. Sucrose was not effective as an inducer, but it stimulated cell growth and enhanced the enzyme productivities with soluble starch.     

Glycine Activating Enzyme in the Posterior Silkgland of Silkworm

1. Aminoacyl tRNA synthetase was extracted from the silkgland of silkworm (Bombyxmori Linné) and fractionated on a DEAE-cellulose column. Activities were estimated by ATP-PP_i exchange reaction as well as glycyl tRNA formation.

2. Two peaks, A and B, having ATP-PP_i exchange activity were found in the separated fractions, respectively. There was also observed a marked difference between the both peaks with respect to the pH optimum and activity dependence on MgCl₂ concentration.

3. Peak A showed no activity of glycyl tRNA formation. Only a part of peak B coincided with the activity of glycyl tRNA formation. The activities of both the ATP-PP_i exchange reaction and glycyl tRNA formation were found to be dependent on MgCl₂ concentration, and the optimum concentration was different between two peaks.

4. It also seemed to exist two peaks of activities, a and b, in glycyl tRNA formation which could be separated with a DEAE-cellulose column.