Effects of spleen cells and serum on transfer of immunity to Strongyloides venezuelensis infection in hypothymic (nude) mice

The course of Strongyloides venezuelensis infection in congenitally hypothymic (nu/nu) mice and their heterozygous thymus-bearing littermates (nu/+) was followed. Unlike the infected nu/+ mice, the nu/nu mice were unable to expel the worms until the end of the observation period (98 days post-infection). In addition, about three times as many eggs were counted at the peak level of infection in faeces of the infected nu/nu mice in comparison with the nu/+ mice. No acquired resistance to rechallenge was observed among the nu/nu mice. Auto-reinfection within the infected nu/nu mice could not be supposed in the present study. The worm expulsion mechanism was generated by nu/nu mice which had been given syngeneic spleen cells from intact +/+ mice. The expulsion of adult worms, as well as the protection against migrating larvae, occurred anamnestically when spleen cells from immune +/+ mice were transferred. The serum transfer, however, only caused a retardation of larval migration. The results support the hypothesis that direct worm immunity and worm expulsion are a T cell-dependent phenomenon.     

Repression of sigK intervening (skin) element gene expression by the CI-like protein SknR and effect of SknR depletion on growth of Bacillus subtilis cells

The Bacillus subtilis phage DNA-like sigK intervening (skin) element (48 kb) is excised from the chromosome by DNA rearrangement, and a composite gene, sigK (spoIIIC and spoIVCB), is created on the chromosome during sporulation. In this study, we first focused on the role of sknR (skin repressor), which has homology with the gene encoding the Xre repressor of defective phage PBSX. The depletion of SknR caused overexpression of the region between yqaF and yqaN (the yqaF-yqaN operon) and a growth defect in B. subtilis. Point mutation analysis and an electrophoretic mobility shift assay (EMSA) suggested that SknR functions as a negative regulator of gene expression in the yqaF-yqaN operon of the skin element through direct interaction with operators of 2-fold symmetry located in the intergenic region between sknR and yqaF. Deletion analysis revealed that the lethal effect of depletion of SknR was related to overexpression of yqaH and yqaM, whose products were previously reported to associate with DnaA and DnaC, respectively. Furthermore, overexpression of either yqaH or yqaM caused cell filamentation and abnormal chromosome segregation, which suggested that overproduction of these proteins inhibits DNA replication. Moreover, overexpression of yqaM inhibited the initiation of replication. Taken together, these data demonstrate that the B. subtilis skin element carries lethal genes, which are induced by the depletion of sknR.     

Isolation and characterization of microsatellite loci in a polyploid alpine herb,Callianthemum miyabeanum (Ranunculaceae)

• Premise of the study: Nuclear microsatellite primers were developed to analyze the clonal diversity and population genetic structure of the endemic polyploid herb Callianthemum miyabeanum. • Methods and Results: Using a protocol for constructing microsatellite-enriched libraries, 15 primer sets were developed for use in C. miyabeanum. The number of alleles found ranged from five to 22. The estimated range of expected heterozygosities was 0.574 to 0.907, and the Shannon–Weiner diversity index ranged from 1.061 to 2.733. Cross-amplification of all loci was also successful in the closely related endemic species C. kirigishiense and C. hondoense. • Conclusions: The development of these microsatellite loci will facilitate a deeper understanding of the genetic diversity, mode of reproduction, and population structure of not only C. miyabeanum, but also the other Callianthemum species endemic to Japan.     

Nucleic acid binding and mutagenicity of active metabolites of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a potent mutagen and carcinogen present in heated foodstuffs. The covalent binding of MeIQx to calf thymus DNA and calf liver RNA with microsomal activation was demonstrated. A major metabolite which exerts a direct mutagenic effect on S. typhimurium TA98 was found by HPLC analysis after incubation of MeIQx with rat liver microsomal fraction. The metabolite was identified as 2-hydroxyamino-3,8-dimethylimidazo[4,5-f]quinoxaline (N-OH-MeIQx). Synthetic N-OH-MeIQx was found to bind non-enzymatically to DNA and RNA at neutral pH even at 0 degrees C. Addition of acetic anhydride increased the binding of N-OH-MeIQx to DNA 10 times. These results suggest that MeIQx is metabolized to N-OH-MeIQx by microsomal cytochrome P-450 and further activated to an acetylated form that binds efficiently to nucleic acids in rat liver. Preferential modification of polyguanylic acid suggests that guanine residues of DNA are mainly modified with MeIQx. Synthetic N-OH-MeIQx exerted direct mutagenic activity on S. typhimurium TA98 inducing 150,000 rev/micrograms. Pentachlorophenol (PCP) caused a dose-dependent inhibition of this mutagenic effect, but 2,6-dichloro-4-nitrophenol (DCNP) did not. Thus the acetyltransferase of S. typhimurium seems to be important for the high mutagenicity of MeIQx after its microsomal activation.     

4-Hydroxy hexenal derived from dietary n-3 polyunsaturated fatty acids induces anti-oxidative enzyme heme oxygenase-1 in multiple organs

It has recently been reported that expression of heme oxygenase-1 (HO-1) plays a protective role against many diseases. Furthermore, n-3 polyunsaturated fatty acids (PUFAs) were shown to induce HO-1 expression in several cells in vitro, and in a few cases also in vivo. However, very few reports have demonstrated that n-3 PUFAs induce HO-1 in vivo.     

Discovery of novel N-acylsulfonamide analogs as potent and selective EP3 receptor antagonists

A series of novel N-acylsulfonamide analogs were synthesized and evaluated for their binding affinity and antagonist activity for the EP3 receptor subtype. Representative compounds were also evaluated for their inhibitory effect on PGE₂-induced uterine contraction in pregnant rats. Among those tested, a series of N-acylbenzenesulfonamide analogs were found to be more potent than the corresponding carboxylic acid analogs in both the in vitro and in vivo evaluations. The structure activity relationships (SAR) are also discussed.