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Background Lactobacilli show anti-inflammatory effects in the human intestine, and their genomic DNA was identified as one of the anti-inflammatory components. Increased levels of the natural protease inhibitor elafin in the intestine plays an important role in protection against intestinal inflammation. However, there have been no previous reports regarding whether lactobacilli increase elafin levels. Objective This study was performed to investigate whether Lactobacillus plantarum induces elafin secretion from the human epithelial colorectal adenocarcinoma cell line, Caco-2. Moreover, we examined the roles of bacterial genomic DNA and toll-like receptor 9 (TLR9), a specific receptor of bacterial DNA, in this effect. Methods Elafin secretion from Caco-2 cells by live and heat-killed L. plantarum was measured. The analysis was also performed using DNase-treated L. plantarum and genomic DNA extracted from L. plantarum. We examined the role of TLR9 in elafin secretion by L. plantarum and its genomic DNA by suppressing TLR9 expression using RNAi in Caco-2 cells. Results Heat-killed L. plantarum time- and dose-dependently increased elafin secretion, whereas live L. plantarum had no such effect. The elafin secretion by heat-killed L. plantarum was partially abolished by DNase treatment of the bacterium. In addition, L. plantarum genomic DNA also increased elafin secretion. Furthermore, suppression of TLR9 expression partially or completely abolished elafin secretion by heat-killed L. plantarum and its genomic DNA. Conclusion Our results indicated that heat-killed L. plantarum induced genomic DNA-dependent and TLR9-mediated elafin secretion. The anti-inflammatory effects of lactobacilli may be mediated by increases in the levels of elafin in the intestine.

Genomic DNA has been identified as an anti-inflammatory component of Lactobacillus species, the effects of which are mediated through toll-like receptor (TLR) 9. In this study, we identified 14 novel anti-inflammatory oligodeoxynucleotide (ODN) from the genomic DNA of Lactobacillus casei by measuring their effects on the secretion of interleukin (IL)-8 (CXCL8) in the human epithelial colorectal adenocarcinoma cell line Caco-2 cells. The ODN TTTTGCCG strongly decreased IL-8 secretion. In the genomic DNA of Lactobacillus species, the frequency of TTTTGCCG was highest in the genomic DNA of L. casei and similar among strains of L. casei. Decreases in inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expressions in macrophage-like differentiated THP-1 cells confirmed the anti-inflammatory effect of TTTTGCCG. Furthermore, oral administration of TTTTGCCG ameliorated dextran sodium sulfate (DSS)-induced murine colitis and DSS-induced increased expression of inflammatory factor mRNAs, such as macrophage inflammatory protein (MIP)-2 (CXCL2), iNOS, and COX-2. The anti-inflammatory effect of TTTTGCCG was mainly regulated by an increase in heat shock protein (Hsp) 70 expression in the epithelium. TLR9 and Hsp90 may primarily mediate the anti-inflammatory effect of TTTTGCCG on Hsp70 signaling.

Pyriproxyfen is a juvenile hormone mimic of vital importance for insect development with little risk to humans. This study was performed to investigate whether large doses of pyriproxyfen affect the immune response in mammals. Mice were immunized thrice with ovalbumin in 5% ethanol, with or without pyriproxyfen or alum. Large doses of pyriproxyfen (9 or 15 mM) significantly enhanced specific total IgG immune response. This enhancement was no longer present 24 hr after treatment with pyriproxyfen. These results suggest that pyriproxyfen is a safe chemical. Moreover, pyriproxyfen induced higher titers of IgG2a and enhanced tumor necrosis factor-alpha and gamma-interferon responses whereas alum induced IgG1 with enhanced interleukin-4 and -10. These observations indicate that the mechanism of immune enhancement by pyriproxyfen may differ from that of alum.

Lactic acid bacteria (LAB) show anti-inflammatory effects, and their genomic DNA was identified as one of the anti-inflammatory components. Despite the differences in anti-inflammatory effects between live LAB dependent not only on genus but also species, this effect has not been compared at the genomic DNA level. We compared the anti-inflammatory effects of the genomic DNA from five Lactobacillus species-Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus gasseri, Lactobacillus plantarum, and Lactobacillus reuteri-using Caco-2 cells. To evaluate anti-inflammatory effects, decreases in H(2)O(2)-induced IL-8 secretion and inhibition of H(2)O(2)-induced NF-κB/IκB-α system activation were examined. All LAB genomic DNAs dose-dependently decreased H(2)O(2)-induced IL-8 secretion and inhibited H(2)O(2)-induced NF-κB/IκB-α system activation. Comparison of these effects between Lactobacillus species showed that the anti-inflammatory effects of L. acidophilus genomic DNA are lower than those of the other species. Furthermore, suppression of Toll-like receptor 9 (TLR9), a specific receptor of bacterial DNA, expression by RNAi abolished the decrease of H(2)O(2)-induced IL-8 secretion and inhibition of H(2)O(2)-induced NF-κB/IκB-α system activation by LAB genomic DNA. Our results demonstrated that the anti-inflammatory effects of genomic DNA differ between Lactobacillus species and TLR9 is one of the major pathways responsible for the anti-inflammatory effect of LAB genomic DNA.

Lactic acid bacteria (LAB) are used in various fields, including in food and medical supplies. There has been a great deal of research into vaccine development using LAB as carriers due to their "generally recognized as safe" status. Cholera is an infectious disease that causes diarrhea due to cholera toxin (CT) produced by Vibrio cholerae. The pentameric cholera toxin B (CTB) subunit has no toxicity, and is used as an antigen in cholera vaccines and as a delivery molecule in vaccines to various diseases. In this study, we generated recombinant LAB expressing and secreting CTB. Here, we first report that CTB expressed and secreted from LAB bound to GM1 ganglioside. The secreted CTB was purified, and its immunogenicity was determined by intranasal administration into mice. The results of the present study suggested that it may be useful as the basis of a new oral cholera vaccine combining LAB and CTB.

Background: MF59, which is an adjuvant belonging to C30 member of the terpene family, is a T helper type-2 (Th2)-biased immune enhancer. Our previous studies showed that pyriproxyfen, a member of the terpene family with fewer carbon atoms (C20) than MF59, enhanced active T helper type-1 (Th1)-biased immune responses. Objective: This study was performed to investigate the enhancement of antigen-specific immune responses by myrcene, a member of the terpene family with fewer carbon atoms (C10) than pyriproxyfen. Method: Ovalbumin (OVA) was used as an antigen to determine the effects of myrcene on the immune response. The IgG subtypes and cytokines induced by immunization of OVA with or without myrcene were monitored. Thereafter, we determined the effects of myrcene in the immune response against Ag85B, which is a dominant protective antigen for tuberculosis. Results: The results showed that 0.8 mg/dose of myrcene enhanced antigen-specific total IgG immune response to OVA. Direct mixing of the antigen with myrcene was required for the enhancement of antibody production. Myrcene increased OVA-specific IgG2a titer, suggesting induction of Th1-immune response. The level of Th1 cytokines, IFN-γ was increased at 8 weeks after immunization, although IL-13 was also increased at the same time point. However, finally myrcene was found to increase Ag85B-specific total IgG titers at 5 weeks and specific IgG2a titer was increased at both 5 and 8 weeks. The results suggested that myrcene could enhance Th1 immune response. Conclusions: Myrcene enhanced specific immune responses against OVA and Ag85B. This study suggested the tendency of the enhancement of Th1 immune response by myrcene. Key words: Ag85B, adjuvant, antigen-specific immune response, myrcene, ovalbumin

Three β-N-acetylglucosaminidases, GlcNAcase A, B, and C, were purified from the culture fluid of Lactobacillus casei ATCC 27092, and the molecular weights of these enzymes were estimated to be 54,000, 51,000, and 44,000, respectively, by SDS-PAGE. The production of these GlcNAcases was accelerated by the addition of N-acetylglucosamine to the culture. These enzymes had pIs of about 5.2, an optimum pH of 5.0-5.5, and an optimum temperature of 37-40°C. The K m values of GlcNAcase A, B, and C for p-nitrophenyl-β-N-acetylglucosamine were 0.85, 1.30, and 1.04 mM and those for p-nitrophenyl-β-N-acetylgalactosamine were 39.6, 57.7, and 60.8 mM, respectively.

As a part of systematic investigation of synthesis and biologically active compounds of pyrazole derivatives containing transition metal, several new pyrazole copper(II) complexes 3a−f were synthesized from pyrazole sodium salts 2a−f, which were produced from spiro-pyrazoles 1a−f and sodium hydride by a ring-opening reaction. All the synthesized compounds were characterized by spectroscopic analysis. Pyrazole copper(II) complexes 3a−d and 3f exhibited high DNA cleavage activity in vitro. Furthermore, compounds 3a−f were tested for their growth inhibitory activity in A549 lung cancer, B16F10 murine melanoma, and HeLa human uterine carcinoma cells. Compounds 3c,d displayed moderate B16F10 and HeLa inhibitory activity levels (3c: IC50 = 45 μM in B16F10 cells and 34 μM in HeLa cells, 3d: IC50 = 50 μM in B16F10 cells and 32 μM in HeLa cells).

Infectious diseases, especially, diarrhoea, are responsible for high mortality rates in developing countries. Zinc supplementation shows beneficial effects against such diseases, but the mechanism of action is poorly understood. Here, we examined whether zinc supplementation can improve mucosal innate immunity through induction of antimicrobial peptide secretion from intestinal epithelial cells. Zinc was found to induce secretion of the antimicrobial peptide LL-37 from Caco-2 cell in a dose (0.63 ± 0.09 ng/mL and 0.54 ± 0.06 ng/mL at 20 μM and 50 μM respectively) and time dependent manner. LL-37 secretion increased immediately (1 h) after exposure to 20 μM Zn (0.29 ± 0.04 ng/mL), which continued up to 48 h of exposure (0.58 ± 0.05 ng/mL). Zinc induces the phosphorylation of ERK and p38 MAP kinase and regulates LL-37 secretion through these MAP kinases. Zinc supplementation may have beneficial effects on mucosal innate immunity via secretion of LL-37.

Living organisms require mechanisms regulating reactive oxygen species (ROS) such as hydrogen peroxide and superoxide anion. Catalase is one of the regulatory enzymes and facilitates the degradation of hydrogen peroxide to oxygen and water. Biochemical information on an insect catalase is, however, insufficient. Using mRNA from fat body of the silkworm, Bombyx mori , a cDNA encoding a putative catalase was amplified by reverse transcriptase-polymerase chain reaction and sequenced. The deduced amino acid sequence comprised 507 residues with more than seventy residues forming a scaffold for a heme cofactor conserved. The sequence showed 71% and 66% identities to those of the Drosophila melanogaster and Apis mellifera catalases, respectively; the catalase from B. mori was estimated to be phylogenetically close to that from A. mellifera . The transcripts of the gene and the catalase activity were distributed in diverse tissues of B. mori , suggesting its ubiquitous nature. Using the gene, a recombinant catalase (rCAT) was functionally overexpressed in a soluble form using Escherichia coli , purified to homogeneity, and characterized. The pH-optimum of rCAT was broad around pH 8.0. More than 80% of the original rCAT activity was retained after incubation in the following conditions: at pH 8–11 and 4 °C for 24 h; at pH 7 and temperatures below 50 °C for 30 min. The Michaelis constant for hydrogen peroxide was evaluated to be 28 mM at pH 6.5 and 30 °C. rCAT was suggested to be a member of the typical catalase family.

Superoxide dismutase (SOD) is an enzyme facilitating the removal of superoxide anions from living organisms. This study focused on SOD from the silkworm, Bombyx mori (bmSOD). cDNA encoding bmSOD was amplified by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequence of bmSOD indicated that the residues forming the Cu/Zn binding site are conserved and that the sequence is in 60% identity to that of the Drosophila melanogaster. B. mori SOD was also close to the D. melanogaster SOD in a phylogenetic tree. The bmSOD mRNA and the enzyme activity were widely distributed in diverse tissues. bmSOD functionally overexpressed in Escherichia coli in a soluble form was purified, and its stability was examined. bmSOD at 4 degrees C retained almost all of its original activity after incubation at pH 4-11 for 24 h. Incubation (pH 7) for 30 min at temperatures below 40 degrees C also affected activity insignificantly.

Microwave irradiation at 2450 MHz inactivated the cells of Escherichia coli, Staphylococcus aureus and Candida albicans suspended in a phosphate buffer. The rate of cell inactivation was proportional to that of the increase in temperature accompanied by microwave irradiation. The inactivation rates of E. coli and C. albicans were affected by addition of NaCl and KCl, but not by sucrose. The maximal inactivation effect was exerted at concentrations of 0·5–1·0 mol l−1, and the end-point temperature was the highest at the same salt concentrations. Correlation of both the electroconductivity and di-electric loss of ionic solutions with the heating by microwave irradiation was discussed.

The t(9;22) chromosomal translocation is found in almost all patients with chronic myelogenous leukemia. The resultant Bcr-Abl fusion gene expresses a chimeric fusion protein p210 bcr-abl with increased tyrosine kinase activity. Hematopoietic progenitors isolated from chronic myelogenous leukemia patients in the chronic phase contain constitutively tyrosine-phosphorylated p62 dok protein. p62 dok associates with the Ras GTPase-activating protein (RasGAP), but only when p62 dok is tyrosine phosphorylated. Here we have investigated the interaction between p62 dok and RasGAP and the consequences of p62 dok tyrosine phosphorylation on the activity of RasGAP. We have found that p62 dok is directly tyrosine phosphorylated by p210 bcr-abl , and the sites of phosphorylation are located in the C-terminal half of the p62 dok molecule. We have identified five tyrosine residues that are involved in in vitro RasGAP binding and have found that tyrosine-phosphorylated p62 dok inhibits RasGAP activity. Our results suggest that p210 bcr-abl might lead to the activation of the Ras signaling pathway by inhibiting a key down-regulator of Ras signaling.

alpha-L-Rhamnosidase was extracted and purified from the cells of Pseudomonas paucimobilis FP2001 with a 19.5% yield. The purified enzyme, which was homogeneous as shown by SDS-PAGE and isoelectric focusing, had a molecular weight of 112,000 and an isoelectric point of 7.1. The enzyme activity was accelerated by Ca2+ and remained stable for several months when stored at -20 C. The optimum pH was 7.8; the optimum temperature was 45 degrees C. The Km, V(max) and k(cat) for p-nitrophenyl alpha-L-rhamnopyranoside were 1.18 mM, 92.4 microM x min(-1) and 117,000 x min(-1), respectively. Examination of the substrate specificity using various synthetic and natural L-rhamnosyl glycosides showed that this enzyme had a relatively broader substrate specificity than those reported so far.

A method for rapid determination of viral RNA sequences (RDV) was applied to homogenates of Aedes aegypti collected in Thailand in an area in which dengue fever (dengue hemorrhagic fever) is endemic, using the mosquito cell line C6/36. Nucleic acid sequences of dengue virus type 4 and cell fusing agent virus were detected. This RDV method has the potential to become a standard method for detection of both known and newly emerging, unknown mosquito-borne viruses.

To find new antibacterial leads in the class of hydantoin derivatives, we carried out synthetic investigation and biological evaluation of the title hydantoin derivatives and related compounds. Among the hydantoin derivatives described in this article, compound 3o, in which a 2,6-dichlorophenyl ring was introduced at the N-3 position of the hydantoin nucleus, showed the highest levels of antibacterial activity against both Escherichia coli NBRC14237 (NIHJ) and Staphylococcus aureus ATCC6538P (gram-negative and gram-positive bacteria, respectively) strains.

To find new antibacterial leads in the class of hydantoin derivatives, we carried out synthetic investigation and biological evaluation of the title hydantoin derivatives and related compounds. Among the hydantoin derivatives described in this article, compound 3o, in which a 2,6-dichlorophenyl ring was introduced at the N-3 position of the hydantoin nucleus, showed the highest levels of antibacterial activity against both Escherichia coli NBRC14237 (NIHJ) and Staphylococcus aureus ATCC6538P (gram-negative and gram-positive bacteria, respectively) strains.

In this study, we improved a method for rapid determination of viral RNA sequences (RDV) to overcome the limitations of previous versions. The RDV ver4.0 method can detect RNA sequences with at least 1,000 copies as starting material. A novel virus, which was isolated from field-collected Aedes aegypti larvae in the Phasi Charoen district of Thailand using C6/36 cells, was identified using the RDV ver4.0 protocol. The virus was named Phasi Charoen virus (PhaV). We used a high-throughput pyrosequencing approach to obtain more information about the genome sequence of PhaV. Analysis of a phylogenic tree based on amino acid sequences strongly suggested that PhaV belongs to the family Bunyaviridae.

The function of Cu2+ in the breakage of pBR322 ccc-DNA by d-glucosamine was investigated using agarose gel electrophoresis. The maximal stimulatory effects on the DNA breakage and ·OH production were observed at the same concentration of Cu2+ in an aqueous solution of d-glucosamine. An aqueous solution of d-glucosamine containing 1 mm of Cu2+ generated less O2− and H2O2 than ·OH. The generation of these active oxygens, either in the presence or absence of Cu2+, was affected little by the addition of DNA. Superoxide dismutase inhibited the DNA-breaking action of d-glucosamine in the absence, but not the presence, of Cu2+. Hydroxyl radical-scavengers inhibited the reaction in the presence as well as the absence of Cu2+. The reaction in the presence of Cu2+ was inhibited by d-GMP and a different kind of DNA. An atomic absorption analysis showed that copper binding to pBR322 ccc-DNA was concentration-dependent. Cupric ions were found to bind to the ccc-DNA, and were found to stimulate the autoxidation of d-gl...

This study focused on glutathione S-transferase (GST), one of the detoxification enzymes, from the silkworm, Bombyx mori (GSTT1). A cDNA encoding a putative GST was amplified by reverse transcriptase-polymerase chain reaction and sequenced. The deduced amino acid sequence revealed 59%, 57% and 56% identities to theta-class GSTs of Musca domestica, Anopheles gambiae and Drosophila melanogaster, respectively. GSTT1 was also estimated to be close to those GSTs in a phylogenetic tree. Recombinant GST (rGSTT1) was functionally overexpressed in Escherichia coli in a soluble form, purified to homogeneity, and characterized. The pH-optimum of rGSTT1 was broad from pH 4 to 9 and rGSTT1 retained more than 75% of its original activity after incubation at pH 5-11. Incubation for 30 min at temperatures below 50 degrees C also affected the activity insignificantly. The Michaelis constant for 1-chloro-2,4-dinitrobenzene was 0.48 mM.

We compared the use of wet and dry two-dimensional electrophoresis (2-DE) gels for in-gel tryptic digestion and subsequent analysis by mass spectrometry, first using bovine serum albumin (BSA) as a model protein and then using unknown proteins from an extract of the silkworm midgut. The gel was either dried at 80 degrees C or left wet. Upon analysis of BSA, there was little difference in peptide recovery from 2-DE or in mass spectrum between the dry and the wet gels. The midgut extract was resolved into more than 1,100 protein spots by 2-DE, and 40 of these spots were sampled for further analysis. For all of the 40 proteins, the results obtained from dry and wet gels were quite similar in mass spectra and protein identification, although the relative amounts of peptides from tryptic digestion ranged from 45 to 146%. Based on these results, we confirmed the utility of dry electrophoretic gels for proteomics of insect extracts.

The gene (rhaM) encoding the alpha-L-rhamnosidase of Sphingomonas paucimobilis FP2001 was cloned, sequenced, and expressed in Escherichia coli. The rhaM consisted of 3,354 nucleotides and had a promoter and Shine-Dalgarno sequences typical in bacteria. The rhaM encoding a protein (Rham) deducted from the sequence consisted of 1,117 amino acids and had a putative signal peptide of 25 amino acids. Rham has no similarity to other known rhamnosidases. Rham has a sugar-binding domain of glycoside hydrolase family 2, which has been well conserved in beta-glucuronidase, beta-mannosidase, and beta-galactosidase, in its C-terminal region. Rham is possibly a member of a new bacterial subfamily in glycoside hydrolase family 78 (alpha-L-rhamnosidase). RT-PCR analysis of rhaM mRNA indicated that the induction of alpha-L-rhamnosidase by the addition of L-rhamnose occurred on the transcriptional level.

The genes encoding the host cell wall-lytic proteins were searched in the genome DNA of phage PL-1 active against Lactobacillus casei ATCC 27092 by comparing the amino acid sequences with those of others using a computer software of the DDBJ data base. The gene regions found were cloned into E. coli by inserting PCR-amplified DNA fragments into the EcoRI site of pUC 19, and the nucleotide sequences were determined. One of the ORFs (hol) consisted of 270 bp encoding 90 amino acids. The hol product (holin) possessed a putative secretion signal, two putative transmembrane helices, and a highly charged C-terminus. Another ORF (lys) consisted of 1050 bp encoding an N-acetylmuramoyl-L-alanine amidase of 350 amino acids. The gene lys was expressed in E. coli using pCALn expression vector, and the purified gene product hydrolysed the amide linkage in the peptidoglycans of L. casei. The amino acid sequence of PL-1 amidase showed a high homology to those of Lactococcus lactis phage rlt and Listeria monocytogenes phage A511. It was suggested that the N-terminal region was involved in enzyme activity and the C-terminal region in binding the enzyme to the cell wall substrate, respectively.

The gene encoding beta-N-acetylglucosaminidase (GlcNAcase) of Lactobacillus casei ATCC 27092 was cloned and expressed in Escherichia coli. The gene consisted of 1581 nucleotides, and had a promoter, Shine-Dalgarno, and rho-independent type transcription termination sequences typical in bacteria. The protein deduced from the sequence consisted of 526 amino acids, and had a putative signal peptide of 14 amino acids and 5 possible asparagine-linked glycosylation sites. A conserved sequence was homologous to the 12 other hexosaminidases from different origins. The recombinant GlcNAcase (r-GlcNAcase) purified from the transformed E. coli had a MW of 39 kDa and lacked oligosaccharide chains. The isoelectric point and the optimum pH for the activity of r-GlcNAcase were similar to those of original GlcNAcases (o-GlcNAcase). However, the thermal stability was lower, and sensitivity to Cd2+, Fe2+, Cu2+ and sodium dodecyl sulfate (SDS) was higher than those of o-GlcNAcases, suggesting that the oligosaccharide moieties of the enzyme contribute to their stability. The Km value for p-nitrophenyl-N-acetyl-beta-1,4-D-glucosamine (PNP-GlcNAc) of r-GlcNAcase (6.4 microM) implied that the affinity of r-GlcNAcase for the substrate was 200-fold higher than that of the original ones.

The effect of microwave irradiation on the survival of bacteriophage PL-1, which is specific for Lactobacillus casei, was studied using a commercial 2,450 MHz microwave oven. The phages were inactivated by microwave irradiation according to almost first-order reaction kinetics. The rate of phage inactivation was not affected by the difference in the continuous or intermittent irradiation, nor by the concentrations of phages used, but was affected by the volume of phage suspensions, which prevented the loss of generated heat. Microwave irradiation of phage suspensions produced a number of ghost phages with empty heads, but fragmentation of the tail was hardly noticed. The breakage of phage genome DNA was primarily caused by the heat generated by microwave irradiation, whereas the phage DNA was not affected by the same temperature achieved by heat from outside. Thus we concluded that the phage-inactivating effect of microwave irradiation was mainly attributed to a thermal microwave effect, which was much stronger than a simple thermal exposure.

The generation of active oxygen molecules, O2-, H2O2, and OH, from the aqueous solution of aminosugars, such as D-glucosamine, was confirmed by their actual measurement. Both the C-2 amino and C-1 aldehyde groups in the aminosugar molecules were indispensable for the generation of active oxygen molecules. The introduction of a C-6 phosphate group to D-glucosamine or the simultaneous use of phosphate ion and D-glucosamine heightened the original activity of D-glucosamine to generate these oxygens, especially OH. Cu2+, which promoted the DNA-breaking activity of aminosugar most at 1 millimolar, also promoted the generation of OH most greatly at the same concentration, but neither O2- nor H2O2 was generated under the same conditions. Superoxide dismutase, catalase, and some radical scavengers inhibited the generation of these active oxygen molecules. Among the active oxygen molecules, only the amount of OH generated was directly proportional to the DNA-breaking activity of the aminosugar.

32P-End-labeled restriction fragments derived from pBR322 and pUC9 DNAs were reacted with D-glucosamine or D-glucosamine-6-phosphate in the presence of Cu2+, and, after being heated at 90 degrees C in aqueous piperidine, the DNA products were analyzed on polyacrylamide gels for the sequence-specificity of alkali-labile cleavaged sites. The intensity of oligonucleotide bands of cleavaged sites was directly proportional to the concentration of aminosugars, indicating that the DNA cleavage was caused by the action of aminosugars themselves. The preferred DNA cleavage sites induced by these aminosugars were identical, both at pyrimidine-purine (5'----3') sequences, especially at thymineguanine ones, and to some extent at pyrimidine-pyrimidine (5'----3') sequences. The 6-phosphate moiety of D-glucosamine did not affect the specificity of DNA cleavage.

DNA strand scission due to aminosugars and their derivatives in plasmid pBR322 was investigated through agarose gel electrophoresis. d-Glucosamine and its related aminosugars primarily caused single-strand scission of ccc-DNA to form oc-DNA in a time- and temperature-dependent manner. The degree of reaction was also related to the concentration of aminosugars. d-Glucosamine-6-phosphate was the most active among the compounds tested, and converted oc-DNA into linear-DNA and further fragmented DNA. The reaction was stimulated by Cu2+ and inhibited by catalase, superoxide dismutase, and some radical scavengers. The DNA strand-scissoring activities of aminosugars were related to their nitroblue tetrazolium-reducing activities. These results support a hypothetic mechanism in which some free radicals, generated during autoxidation of aminosugars in aqueous solution, are involved in DNA strand scission.

d-Glucosamine selectively inactivated free PL-1 phage under the conditions in which the growth of host cells, Lactobacillus casei ATCC 27092, was not affected. Both the N-acetylated and non-aminated forms little affected the phage infectivity. The rate of phage inactivation by D-glu-cosamine was proportional to the time and temperature of the incubation, and about 0.1 m d-glucosamine showed the maximum inactivation effect. The phage inactivation was stimulated by Cu2 +, and inhibited by catalase and several oxygen radical scavengers. The inactivated phage was identical with the intact one with respect to the electron microscopic appearance, the density and the ability of combining with host cells. The DNA in the virion was fragmented by D-glucosamine and the DNA fragmentation was also stimulated by Cu2 +. With plasmid pBR322, d-glucosamine caused single-strand scission of ccc-DNA to give oc- and in succession linear-DNA. The inactivation of PL-1 phage by d-glucosamine was considered to be due to single-st...

The effect of methanol on the frequency of cytoplasmic respiration-deficient (RD) mutation induced by ethidium bromide was investigated in Saccharomyces cerevisiae. When growing cells were treated with ethidium bromide at concentrations higher than 1.0μg/ml, 95 to 100% of surviving cells were RD mutants as judged by the tetrazolium overlay method. The RD mutants induced by 1.0μg/ml ethidium bromide were drastically decreased by addition of 6-8% methanol in both growing and non-growing conditions. Methanol reduced uptake of ethidium bromide by yeast cells, but it did not modify the inhibitory effect of ethidium bromide on in vitro yeast mitochondrial deoxyribonucleic acid synthesis.

Background Lactobacillus species are used as bacterial vectors to deliver functional peptides to the intestine because they are delivered live to the intestine, colonize the mucosal surface, and continue to produce the desired protein. Previously, we generated a recombinant Lactobacillus casei secreting the cholera toxin B subunit (CTB), which can translocate into intestinal epithelial cells (IECs) through GM1 ganglioside. Recombinant fusion proteins of CTB with functional peptides have been used as carriers for the delivery of these peptides to IECs because of the high cell permeation capacity of recombinant CTB (rCTB). However, there have been no reports of rCTB fused with peptides expressed or secreted by Lactobacillus species. In this study, we constructed L. casei secreting a recombinant fusion protein of CTB with YVAD (rCTB–YVAD). YVAD is a tetrapeptide (tyrosine–valine–alanine–aspartic acid) that specifically inhibits caspase-1, which catalyzes the production of interleukin (IL)-1β, an inflammatory cytokine, from its inactive precursor. Here, we examined whether rCTB–YVAD secreted by L. casei binds to GM1 ganglioside and inhibits caspase-1 activation in Caco-2 cells used as a model of IECs. Results We constructed the rCTB–YVAD secretion vector pSCTB–YVAD by modifying the rCTB secretion vector pSCTB. L. casei secreting rCTB–YVAD was generated by transformation with pSCTB–YVAD. Both the culture supernatant of pSCTB–YVAD-transformed L. casei and purified rCTB–YVAD bound to GM1 ganglioside, as did the culture supernatant of pSCTB-transformed L. casei and purified rCTB. Interestingly, although both purified rCTB–YVAD and rCTB translocated into Caco-2 cells, regardless of lipopolysaccharide (LPS), only purified rCTB–YVAD but not rCTB inhibited LPS-induced caspase-1 activation and subsequent IL-1β secretion in Caco-2 cells, without affecting cell viability. Conclusions The rCTB protein fused to a functional peptide secreted by L. casei can bind to GM1 ganglioside, like rCTB, and recombinant YVAD secreted by L. casei may exert anti-inflammatory effects in the intestine. Therefore, rCTB secreted by L. casei has potential utility as a vector for the delivery of YVAD to IECs.

Background Mosquito-borne viruses are transmitted to human hosts via blood-feeding behavior of female mosquitoes. Female mosquitoes seek a host to take blood meals (host-seeking behavior). In order to prevent virus infections, it is important to understand how they modulate host-seeking behavior. Dopamine (DA) in the central nervous system acts as a neuromediator that regulates a variety of behaviors in insects. In female mosquitoes, host-seeking behavior increases when DA levels in the head decline after emergence. However, it remains unclear whether DA directly modulates host-seeking behavior in female mosquitoes. The aim of this study was to examine whether changes in DA levels in the head affects host-seeking activity in the adult female mosquito Aedes albopictus (Ae. albopictus). Findings We compared host-seeking behavior in one group of emerging female adults treated with l-β-3,4-dihydroxyphenylalanine (l-DOPA), the precursor of DA, (l-DOPA group), with that in an untreated control (control group) after confirming elevation of head DA in l-DOPA group by using high-performance liquid chromatography. The content of head DA in l-DOPA group significantly remained higher than that in controls on all days examined. The host-seeking activity in the control group showed a gradual increase over the 6-day experimental period. In contrast, there was no such increase in the host-seeking activity in the l-DOPA group. Therefore, the host-seeking activity of l-DOPA group was significantly lower than that of the controls between day 3 and 6 post-emergence. Conclusion Our results indicate that elevation of DA level reduces host-seeking activity in adult female mosquito Ae. albopictus.