Evidence for lateral transfer of the Suilysin gene region of Streptococcus suis

Suilysin is a cholesterol-binding cytolysin encoded by sly in Streptococcus suis. DNA sequence determination of the sly locus in a strain lacking sly revealed the presence of another gene, designated orf102, in the place of sly. No transposable element or long-repeat sequence was found in the close vicinity. Except for six strains whose corresponding loci have been rearranged, all of the remaining 62 strains examined had either sly or orf102 at the same locus and their flanking regions were conserved. The genetic organizations having either sly or orf102 were found in the strains whose 16S rRNA sequences were identical. These results suggest that S. suis acquired sly or orf102 from a foreign source and that these genes subsequently spread among S. suis strains by homologous recombination.     

Inhibition of excystation and metacystic development of Entamoeba invadens by the dinitroaniline herbicide oryzalin

The effect of oryzalin on excystation and metacystic development of Entamoeba invadens strain IP-1 was examined by transfer of cysts to a growth medium containing the drug. Excystation, which was assessed by counting the number of metacystic amoebae after induction of excystation, was inhibited by oryzalin in a concentration-dependent manner. Metacystic development, which was determined by the number of nuclei in metacystic amoebae, was also inhibited by oryzalin because the percentage of 4-nucleate amoebae at day 1 remained unchanged at day 3. The addition of oryzalin after the induction of excystation decreased the number of metacystic amoebae, compared with control cultures. When cysts were incubated for 1 day in growth medium plus oryzalin, little increase in the number of metacystic amoebae was observed after removal of the drug. Excystation and metacystic development were further inhibited when the cysts were incubated for 30 min in encystation medium containing oryzalin before transfer to growth medium with the drug. When cysts were incubated for 30 min in encystation medium before transfer to growth medium without the drug, metacystic amoebae decreased in number. Pretreatment of cysts with oryzalin for 30 min in phosphate-buffered saline markedly reduced viability and prevented excystation in growth medium with or without the drug. The results indicate that oryzalin inhibits excystation and metacystic development of E. invadens, suggesting that it may be an inhibitor of Entamoeba infection.     

Cytology of basaloid squamous carcinoma of the bronchus. A case report

BACKGROUND: The cytologic appearance of basaloid squamous carcinoma (BSC) arising in the lower respiratory tract has not been described very well because of its rarity. This article describes a surgical case of bronchial BSC and provides the first documentation of the sputum and imprint cytologic features of the tumor. CASE: A 74-year-old man presented with hemoptysis. An abnormal intrabronchial mass was revealed by computed tomography and bronchoscopy. Preoperative cytology and biopsy showed that the mass was composed of small, round, atypical cells, but correct diagnosis was difficult. Under a tentative diagnosis of small round cell carcinoma, a right lobectomy was performed. The resected tumor was composed of small cells showing peripheral palisading and partial epidermoid differentiation. There was no glandular differentiation. Focal necrosis was also noted. Immunohistochemical markers for smooth muscle and neuroendocrine cells were negative. The tumor was eventually diagnosed as BSC or basaloid carcinoma (BC) with squamous differentiation. CONCLUSION: It is important to recognize this disease, especially when undetermined small round cell carcinoma is noted in cytologic specimens, in order to properly assess prognosis. Cytologic detection of nuclear palisading of the neoplastic cells, one of the hallmarks of the disease, may be difficult, however, careful examination to reveal neoplastic cells showing squamous differentiation appears helpful for diagnosis.     

Identification of a toxic mechanism of the plasticizers,phtahlic acid esters,which are putative endocrine disrupters: time-dependent increase in quinolinic acid and its metabolites in rats fed di(2-ethylhexyl)phthalate

We have reported that the administration of di(2-ethylhexyl)phthalate (DEHP) increased the formations of quinolinic acid (QA) and its lower metabolites on the tryptophan-niacin pathway. To discover the mechanism involved in disruption of the tryptophan-niacin pathway by DEHP, we assessed the daily urinary excretion of QA and its lower metabolites, and enzyme activities on the tryptophan-niacin pathway. Rats were fed with a niacin-free, 20% casein diet or the same diet supplemented with 0.1% DEHP or 0.043% phthalic acid and 0.067% 2-ethylhexanol added for 21 days. Feeding of DEHP increased the urinary excretions of QA and its lower metabolites in a time-dependent manner, and the increase of these excretions reached a peak at 11 days, but feeding of phthalic acid and 2-ethylhexanol had no effect. Feeding of DEHP, however, did not affect any enzyme activity including alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), affecting the formation of QA, on the tryptophan-niacin pathway.     

A simple method for enrichment of uninucleate conidia of Aspergillus oryzae

Aspergillus oryzae produces multinucleate conidia, which makes the obtaining of homokaryons labor-intensive. Analysis of conidia by flow cytometry clarified the relationship that conidia of lower nuclear number were smaller in size. Based on this, we have developed a simple way to enrich uninucleate conidia with a membrane filter. Our results also suggest that the method is useful for elimination of heterokaryons.     

In situ alkylation with acrylamide for identification of cysteinyl residues in proteins during one- and two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis

Cysteinyl residues in proteins were alkylated with acrylamide during sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) to yield a thioether derivative, cys-S-beta-propionamide (PAM cys). The process was termed in situ alkylation with acrylamide. Using this method, the recovery of PAM-cys peptides from bovine serum albumin (BSA) was 88.6% at 10 picomol in one-dimensional (1-D) SDS-PAGE and 97.1% at 50 picomol in two-dimensional (2-D) SDS-PAGE. The coverage of tryptic peptide of BSA in 1-D and 2-D SDS-PAGE was 83.7% and 81.1%, respectively. The advantages of in situ alkylation with acrylamide were the following: (i) cysteinyl peptides were effectively derived in a single PAM cys and then proteins were precisely identified using databases; (ii) marked reduction of salts compared with post alkylation, e.g., using carboxymethylamide (CAM), resulting in higher signal intensity and wider coverage of cysteinyl peptides from PAM cys, compared with those of CAM derivatives, in mass spectrometry peptide mapping; and (iii) shorter duration by excluding the processes of post alkylation and desalting before peptide mapping.     

Structure-function relationship of bromelain isoinhibitors from pineapple stem

Bromelain isoinhibitors from pineapple stem (BIs) are unique double-chain inhibitors and inhibit the cysteine proteinase bromelain competitively. The three-dimensional structure was shown to be composed of two distinct domains, each of which is formed by a three-stranded anti-parallel beta-sheet. Unexpectedly, BIs were found to share similar folding and disulfide-bond connectivities not with the cystatin superfamily, but with Bowman-Birk trypsin/chymotrypsin inhibitor (BBI). The structural similarity between them suggests that BIs and BBI have evolved from a common ancestor and differentiated in function during the course of molecular evolution.     

Interleukin-13 induces thymus and activation-regulated chemokine (CCL17) in human peripheral blood mononuclear cells

BACKGROUND: In allergic inflammation involving allergic rhinitis, the predominance of Th(2) lymphocytes is one of the primary causal agents in promotion of the allergic condition. Thymus and activation-regulated chemokine (TARC/CCL17) is a recently identified chemokine that induces the development of Th(2) lymphocytes. One of the sources of TARC has been reported to be peripheral blood mononuclear cells (PBMCs). OBJECTIVE: We investigated TARC production from PBMCs by the stimulation of specific antigens and Th(2) type cytokines. METHOD: PBMCs were isolated from both allergic rhinitis patients and healthy volunteers. PBMCs were incubated with cytokine. TARC mRNA expression was examined by real time PCR methods and the amount of TARC production was examined by ELISA. RESULTS: IL-13 was found to be the most potent inducer for TARC mRNA expression and protein production in PBMCs. Furthermore, tumour necrosis factor alpha and IL-13 synergistically induce TARC. The amount of TARC from allergic rhinitis patients was significantly larger than that from healthy volunteers. Moreover, TARC was induced by a specific antigen, and was 35% inhibited by an anti-IL-13 neutralizing antibody. CONCLUSION: These results indicate that IL-13 is important in TARC mediated Th(2) lymphocytes infiltration in the nasal mucosa.