Diversity of the bacterial community in Myanmar traditional salted fish <Emphasis Type="Italic">yegyo ngapi</Emphasis>

The distribution and characterization of bacteria including lactic acid bacteria (LAB) in the traditional and popular salted fish yegyo ngapi in Myanmar were studied to clarify the contribution of these bacteria to the curing and ripening of this product. Samples of yegyo ngapi purchased from a market in Yangon were used. Most of the isolates obtained using de Man, Rogosa and Sharpe medium containing 10 % NaCl were identified as coccoid LAB on the basis of their basic phenotypic characteristics. From the results of 16S rRNA gene sequencing and PCR-restriction fragment length polymorphism analysis of this gene, most of the isolates were identified as the halophilic LAB Tetragenococcus muriaticus. Analyses of the 16S rRNA gene based on the clone library using DNA extracted from salted fish products were also performed. The results of these molecular-analysis-based techniques showed that spore-forming and non-spore-forming anaerobic bacteria including the genera Clostridium and Halanaerobium in addition to T. muriaticus were also frequently found in bacterial communities. These findings suggest that the anaerobic condition during curing and ripening resulted in bacterial communities composed of strictly anaerobic bacteria and halophilic LAB, and that these bacteria might also contribute to the manufacturing processes of this product. In addition, DNA sequences similar to that of Clostridium botulinum were found in the clone library analysis. Therefore, despite no reports of botulism poisoning from the region where the samples were taken, closer surveillance should be carried out from the viewpoint of food safety.     

Purification and characterization of the intracellular β-glucosidase from Aureobasidium sp ATCC 20524

β-Glucosidase hydrolyzing cellobiose was extracted from Aureobasidium sp ATCC 20524 and purified to homogeneity. The molecular mass was estimated to be about 331 kDa. The enzyme contained 26.5% (w/w) carbohydrate. The optimum pH and temperature for the enzyme reaction were pH 4 and 80°C, respectively. The enzyme was stable at a wide range of pH, 2.2–9.8, after 3 h and at 75°C for 15 min. The kinetic parameters were determined. The enzyme was relatively stable against typical organic enzyme inhibitors. The enzyme also hydrolyzed gentiobiose, p-nitrophenyl-β-glucoside and salicin. Received 05 November 1998/ Accepted in revised form 14 February 1999     

Resistance of Crohn's disease T cells to multiple apoptotic signals is associated with a Bcl-2/Bax mucosal imbalance.

Crohn's disease (CD) is a condition characterized by excessive numbers of activated T cells in the mucosa. We investigated whether a defect in apoptosis could prolong T cell survival and contribute to their accumulation in the mucosa. Apoptotic, Bcl-2+, and Bax+ cells in tissue sections were detected by the TUNEL method and immunohistochemistry. T cell apoptosis was induced by IL-2 deprivation, Fas Ag ligation, and exposure to TNF-alpha and nitric oxide. TUNEL+ leukocytes were few in control, CD, and ulcerative colitis (UC) mucosa, with occasional CD68+ and myeloperoxidase+, but no CD45RO+, apoptotic cells. Compared with control and UC, CD T cells grew remarkably more in response to IL-2 and were significantly more resistant to IL-2 deprivation-induced apoptosis. CD T cells were also more resistant to Fas- and nitric oxide-mediated apoptosis, whereas TNF-alpha failed to induce cell death in all groups. Compared with control, CD mucosa contained similar numbers of Bcl-2+, but fewer Bax+, cells, while UC mucosa contained fewer Bcl-2+, but more Bax+, cells. Hence, the Bcl-2/Bax ratio was significantly higher in CD and lower in UC. These results indicate that CD may represent a disorder where the rate of T cell proliferation exceeds that of cell death. Insufficient T cell apoptosis may interfere with clonal deletion and maintenance of tolerance, and result in inappropriate T cell accumulation contributing to chronic inflammation.     

Basolateral protein Scribble binds phosphatase PP1 to establish a signaling network maintaining apicobasal polarity

Scribble, a member of the LAP protein family, contributes to the apicobasal polarity (ABP) of epithelial cells. The LAP-unique region of these proteins, which is essential and sufficient for ABP, includes a conserved Leucine-Rich Repeat (LRR) domain. The major binding partners of this region that could regulate ABP remain unknown. Here, using proteomics, native gel electrophoresis, and site-directed mutagenesis, we show that the concave surface of LRR domain in Scribble participates in three types of mutually exclusive interactions—(i) homodimerization, serving as an auto-inhibitory mechanism; (ii) interactions with a diverse set of polarity proteins, such as Llgl1, Llgl2, EPB41L2, and EPB41L5, which produce distinct multiprotein complexes; and (iii) a direct interaction with the protein phosphatase, PP1. Analogy with the complex between PP1 and LRR domain of SDS22, a well-studied PP1 regulator, suggests that the Scibble-PP1 complex stores a latent form of PP1 in the basolateral cell cortex. Such organization may generate a dynamic signaling network wherein PP1 could be dispatched from the complex with Scribble to particular protein ligands, achieving fast dephosphorylation kinetics.     

Identification of minimal sequence for HIV-1 fusion inhibitors

Emergence of multi-drug resistant HIV-1 is a serious problem for AIDS treatment. Recently, the virus-cell membrane fusion process has been identified as a promising target for the development of novel drugs against these resistant variants. In this study, we identified a 29-residue peptide fusion inhibitor, SC29EK, which shows activity comparable to the previously reported inhibitor SC35EK. Some residues in SC29EK not required for interaction with virus gp41 heptad repeat 1 (HR1) were replaced with a non-proteinogenic amino acid, 2-aminoisobutyric acid (Aib), to stabilize the alpha-helix structure and to provide resistance to peptidases.     

Human stem cells for modeling neurological disorders: accelerating the drug discovery pipeline

The availability of human stem cells heralds a new era for modeling normal and pathologic tissues and developing therapeutics. For example, the in vitro recapitulation of normal and aberrant neurogenesis holds significant promise as a tool for de novo modeling of neurodevelopmental and neurodegenerative diseases. Translational applications include deciphering brain development, function, pathologies, traditional medications, and drug discovery for novel pharmacotherapeutics. For the latter, human stem cell-based assays represent a physiologically relevant and high-throughput means to assess toxicity and other undesirable effects early in the drug development pipeline, avoiding late-stage attrition whilst expediting proof-of-concept of genuine drug candidates. Here we consider the potential of human embryonic, adult, and induced pluripotent stem cells for studying neurological disorders and preclinical drug development.     

Antioxidants from steamed used tea leaves and their reaction behavior

The most efficient steaming conditions below 200 degrees C for extracting antioxidants from used tea leaves and their reaction behavior during the steaming treatment were investigated. The antioxidative activity of the steamed extracts increased with increasing steaming temperature, and the yield of the ethyl acetate extract fraction from each steamed extract showing the greatest antioxidative activity also increased. Caffeine, (-)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin, (-)-catechin gallate, (-)-epicatechin gallate, (-)-gallocatechin gallate, (-)-epigallocatechin gallate and gallic acid were identified from the ethyl acetate extract fraction. Quantitative analyses demonstrated that the catechins with a 2,3-cis configuration decreased with increasing steaming temperature, whereas the corresponding epimers at the C-2 position increased. Each pair of epimers showed similar antioxidative activity to each other, indicating that the epimerization reaction did not contribute to the improved antioxidative activity. It is concluded from these results that the improvement in antioxidative activity at higher steaming temperatures was due to the increased yield of catechins and other antioxidants.     

The coexistence of Ser84 in renin and His13 in angiotensinogen brings a pH profile of two separate peaks to the reaction of human renin and sheep angiotensinogen

The pH dependence and kinetics parameters of renin-angiotensinogen reactions were determined using wild-type and S84G mutant human renins and wild-type and H13Y mutant sheep angiotensinogens. It is explained in this report that (i) renin catalyzes acidic and basic reactions of which the optimum pHs are 5.5 and 7.5-8.2 respectively, both of which produce angiotensin I; (ii) Ser84 specific to human renin accelerates the acidic reaction by 75-110% through elevation of V(max), and shifts the optimum pH of the basic reaction from 7.5 to 8.0-8.2; and (iii) His13 specific to sheep angiotensinogen accelerates the acidic and basic reactions by 25-42% through reduction of K(m). It is concluded from these results that the coexistence of Ser84 in renin and His13 in angiotensinogen brings a pH profile of two separate peaks at pHs 5.5 and 8.2 to the reaction of human renin and sheep angiotensinogen.