The vanE operon was characterized from Enterococcus faecalis N00-410 (MIC of vancomycin ‫؍‬ 24 g/ml). The organization of the vanE operon was identical to that of the vanC1 operon from Enterococcus gallinarum, with protein identities ranging from 46 to 63%. An open reading frame located downstream of the vanE operon showed significant homology to a number of integrase genes, all of which are located downstream of the chromosomal GMP synthase gene guaA.In enterococci, normal peptidoglycan precursors have DAla-D-Ala termini that strongly bind vancomycin, whereas in vancomycin-resistant enterococci, alternate biosynthetic pathways lead to precursors with termini that bind vancomycin poorly, thus conferring resistance (4, 18). The vanA (3), vanB (9, 15), and vanD (5, 6, 14) genes code for D-Ala-D-Lac ligases and are responsible for the acquired intermediate-to highlevel resistance found mainly in Enterococcus faecalis and Enterococcus faecium. Intrinsic low-level vancomycin resistance is conferred by vanC1, vanC2, and vanC3, which code for D-Ala-D-Ser ligases found on the chromosomes of Enterococcus gallinarum, Enterococcus casseliflavus, and Enterococcus flavescens, respectively (7, 13). The acquired, nontransferable VanE DAla-D-Ser ligase found in E. faecalis also confers a low-level resistance phenotype (8). The function of the E. faecalis WCH9 putative vancomycin resistance gene vanG is unknown (11). The identification of the first vanE-containing E. faecalis isolated in Canada has recently been reported (17). In this report, we describe the characterization of the vanE resistance locus and the genes flanking this region.E. faecalis N00-410 (MIC of vancomycin ϭ 24 g/ml) (17) and E. faecium ATCC 19434 were grown at 35°C in brain heart infusion broth or cation-adjusted Mueller-Hinton broth. Induction studies were performed as previously described (5). Transfer experiments were attempted by liquid mating with selection on phenol red agar plates (Difco) containing 1% L-arabinose and 5 g of vancomycin/ml (11). Antimicrobial susceptibilities were determined by using Etest strips (AB Biodisk) or agar dilution according to NCCLS guidelines (12) for high levels of streptomycin and gentamicin. Genomic DNA was extracted from enterococci as previously described (5). An N00-410 DNA library (ϳ10-kb Sau3A fragments) in ZAP Express (Stratagene) was screened with a vanE PCR product generated with primers VANE1 and VANE2 (8). Labeling and detection of the probe were performed per the manufacturer's instructions (Amersham Pharmacia Biotech). The sequence was obtained by primer walking and by using the EZ::TNϽTET-1Ͼ insertion kit (Epicentre Technologies). Inverse PCR was carried out with primers vanRE-1 (5Ј-TCTCG GCTTTTCATGCATC-3Ј) and vanSE-DN1 (5Ј-GAATGAAA TTAATCATATTCG-3Ј) and with EcoRV-cut and -religated N00-410 DNA. Primers Eint-DN1 (5Ј-ATTCAAGGGATATT TTCAATAGC-3Ј) and guaDN-1 (5Ј-TTGCACATGTAAAC CGTATCG-3Ј) were used to amplify a 0.9-kb fragment overlapping the inverse PCR product. Homology searches were conducted with BLAST ...

The purpose of this work was to purify a protease from Penicillium waksmanii and to determine its biochemical characteristics and specificity. The extracellular protease isolated that was produced by P. waksmanii is a serine protease that is essential for the reproduction and growth of the fungus. The protease isolated showed 32 kDa, and has optimal activity at pH 8.0 and 35 °C towards the substrate Abz-KLRSSKQ-EDDnp. The protease is active in the presence of CaCl(2), KCl, and BaCl, and partially inhibited by CuCl(2), CoCl(2) and totally inhibited by AlCl(3) and LiCl. In the presence of 1 M urea, the protease remains 50 % active. The activity of the protease increases 60 % when it is exposed to 0.4 % nonionic surfactant-Triton X-100 and loses 10 % activity in the presence of 0.4 % Tween-80. Using fluorescence resonance energy transfer analysis, the protease showed the most specificity for the peptide Abz-KIRSSKQ-EDDnp with k (cat)/K (m) of 10,666 mM(-1) s(-1), followed by the peptide Abz-GLRSSKQ-EDDnp with a k (cat)/K (m) of 7,500 mM(-1) s(-1). Basic and acidic side chain-containing amino acids performed best at subsite S(1). Subsites S(2), S(3), S(') (2), and S(') (1), S(') (3) showed a preference for binding for amino acids with hydrophobic and basic amino acid side chain, respectively. High values of k (cat)/K (m) were observed for the subsites S(2), S(3), and S(') (2.) The sequence of the N-terminus (ANVVQSNVPSWGLARLSSKKTGTTDYTYD) showed high similarity to the fungi Penicillium citrinum and Penicillium chrysogenum, with 89 % of identity at the amino acid level.

Laboratory evidence of a positive effect of sleep on declarative memory consolidation suggests that naps can be used to boost school learning in a scalable, low-cost manner. The few direct investigations of this hypothesis have so far upheld it, but departed from the naturalistic setting by testing non-curricular contents presented by experimenters instead of teachers. Furthermore, nap and non-nap groups were composed of different children. Here we assessed the effect of post-class naps on the retention of Science and History curricular contents presented by the regular class teacher to 24 students from 5th grade. Retention was repeatedly measured 3–4 days after content learning, with weekly group randomization over 6 consecutive weeks. Contents followed by long naps (>30 min), but not short naps (<30 min), were significantly more retained than contents followed by waking (Cohen’s d = 0.7962). The results support the use of post-class morning naps to enhance formal education.

Enzyme production varies in different fermentation systems. Enzyme expression in different fermentation systems yields important information for improving our understanding of enzymatic production induction. Comparative studies between solid-state fermentation (SSF) using agro-industrial waste wheat bran and submerged fermentation (SmF) using synthetic media were carried out to determinate the best parameters for peptidase production by the fungus Aspergillus fumigatus Fresen. Variables tested include: the concentration of carbon and protein nitrogen sources, the size of the inoculum, the pH of the media, temperature, and the length of the fermentation process. The best peptidase production during SSF was obtained after 96 hours using wheat bran at 30 °C with an inoculum of 1 × 106 spores and yielded 1500 active units (U/mL). The best peptidase production using SmF was obtained after periods of 72 and 96 hours of fermentation in media containing 0.5% and 0.25% of casein, respectively, at a pH of 6.0 and at 30 °C and yielded 40 U/mL. We also found examples of catabolite repression of peptidase production under SmF conditions. Biochemical characterization of the peptidases produced by both fermentative processes showed optimum activity at pH 8.0 and 50 °C, and also showed that their proteolytic activity is modulated by surfactants. The enzymatic inhibition profile using phenylmethylsulfonyl fluoride (PMSF) in SmF and SSF indicated that both fermentative processes produced a serine peptidase. Additionally, the inhibitory effect of the ethylene-diaminetetraacetic acid (EDTA) chelating agent on the peptidase produced by SmF indicated that this fermentative process also produced a metallopeptidase.