Molecular analysis of environmental and human isolates of Salmonella typhi.

Molecular characterization of a total of 54 isolates of Salmonella typhi from Santiago, Chile, was performed by pulsed-field gel electrophoresis (PFGE) after digestion of chromosomal DNA with three restriction endonucleases: XbaI (5'-TCTAGA-3'), AvrII (5'-CCTAGG-3'), and SpeI (5'-ACTAGT-3'). Thirteen of the 54 isolates were obtained from environmental sources (sewage and river water), and the rest were isolates from clinical cases of typhoid fever. Considerable genetic diversity was detected among the human isolates obtained in 1994, as evidenced by the presence of 14 to 19 different PFGE patterns among 20 human isolates, with F (coefficient of similarity) values ranging from 0.69 to 1.0 (XbaI), 0.61 to 1.0 (AvrII), and 0.70 to 1.0 (SpeI). A total of eight phage types were detected among these 20 isolates, with 50% possessing the E1 or 46 phage type. There was no correlation between PFGE pattern and phage types. Similar diversity was seen among 21 isolates obtained in 1983, with 17 to 19 PFGE patterns detected and F values of 0.56 to 1.0 (XbaI), 0.55 to 1.0 (AvrII), and 0.67 to 1.0 (SpeI). Comparison of these two groups of human isolates obtained 11 years apart indicated that certain molecular types of S. typhi are shared and are able to persist for considerable periods. A similar degree of genetic diversity was also detected among the environmental isolates of S. typhi, for which 10 to 12 different PFGE patterns were detected among the 13 isolates analyzed, with F values ranging from 0.56 to 1.0 (XbaI), 0.52 to 1.0 (AvrII), and 0.69 to 1.0 (SpeI). Certain molecular types present among the environmental isolates of S. typhi were also found among the human isolates from the same time period, providing evidence for the epidemiological link between environmental reservoirs and human infection.     

Decomposition dynamics of Phragmites australis litter in Lake Burullus,Egypt

This study estimated the decomposition rate and nutrient dynamics of Phragmites australis litter in Lake Burullus (Egypt) and investigated the amount of nutrients released back into the water after the decomposition of the dead tissues. Phragmites australis detritus decomposition was studied from April to September 2003 utilizing the leaf, stem, and rhizome litterbags technique with coarse mesh (5 mm) bags on five sampling dates and with nine replicate packs per sample. All samples were dried, weighed and analyzed for N, P, Ca, Mg, Na, and K concentrations. The exponential breakdown rate of leaves (?0.0117/day) was significantly higher than that of rhizomes (?0.0040/day) and stems (?0.0036/day). N, Na and K mineralization were the highest from leaf litter, followed by rhizomes and stems, while P, Ca and Mg mineralization were the highest from rhizomes, followed by leaves and stems. The dead shoot biomass at the end of 2003 amounted to 4550 g DM/m² which enters the decomposition process. By using the decay rate of 0.0117 and 0.0036/day for the leaves and stems, 3487 g DM/m² is decomposed in a year, leaving only 1063 g DM/m² after 1 year. This is mainly equivalent to releasing the following nutrients into surrounding water (in g/m²): 24.4 N, 1.1 P, 15.5 Ca, 3.5 Mg, 11.3 Na and 16.7 K. In conclusion, the present study indicates a significant difference in relation to the type of litter; these breakdown rates were generally greater than most rates reported in previous studies that used the same technique and mesh size.     

Gastrin induction of mRNA expression in rat colonic epithelium in vitro

A newly developed system of isolated rat colonic epithelial cells was utilized for a comprehensive study of protein synthesis influenced by gastrin. We found that synthetic human gastrin (0.01-100 nM) increased the incorporation of [35S]methionine into proteins within 2 hours. Peak incorporation was observed with 10 nM gastrin to more than two-fold above maintenance levels. Actinomycin-D (10 micrograms/ml) inhibited the stimulated increases in total protein synthesis indicating that the peptide's trophic effect was mediated by the synthesis of new mRNA species. The effect of gastrin was comparably stronger than the one induced by the mitogen bombesin (1 nM). However, bombesin, a neuromodulator of gastrin release, did not produce an additive effect beyond that of gastrin on total protein synthesis. Gastrin stimulated the synthesis of many polypeptides resolved on two-dimensional polyacrylamide gel, an indicator of gastrin's influence on the expression of various mRNA species. Some of these polypeptides may be used as markers in investigating colonic epithelial response to gastrin.     

The C. elegans ric-3 gene is required for maturation of nicotinic acetylcholine receptors

Mutations in ric-3 (resistant to inhibitors of cholinesterase) suppress the neuronal degenerations caused by a gain of function mutation in the Caenorhabditis elegans DEG-3 acetylcholine receptor. RIC-3 is a novel protein with two transmembrane domains and extensive coiled-coil domains. It is expressed in both muscles and neurons, and the protein is concentrated within the cell bodies. We demonstrate that RIC-3 is required for the function of at least four nicotinic acetylcholine receptors. However, GABA and glutamate receptors expressed in the same cells are unaffected. In ric-3 mutants, the DEG-3 receptor accumulates in the cell body instead of in the cell processes. Moreover, co-expression of ric-3 in Xenopus laevis oocytes enhances the activity of the C.elegans DEG-3/DES-2 and of the rat alpha-7 acetylcholine receptors. Together, these data suggest that RIC-3 is specifically required for the maturation of acetylcholine receptors.     

Probiotic Microbes Sustain Youthful Serum Testosterone Levels and Testicular Size in Aging Mice

The decline of circulating testosterone levels in aging men is associated with adverse health effects. During studies of probiotic bacteria and obesity, we discovered that male mice routinely consuming purified lactic acid bacteria originally isolated from human milk had larger testicles and increased serum testosterone levels compared to their age-matched controls. Further investigation using microscopy-assisted histomorphometry of testicular tissue showed that mice consuming Lactobacillus reuteri in their drinking water had significantly increased seminiferous tubule cross-sectional profiles and increased spermatogenesis and Leydig cell numbers per testis when compared with matched diet counterparts This showed that criteria of gonadal aging were reduced after routinely consuming a purified microbe such as L. reuteri. We tested whether these features typical of sustained reproductive fitness may be due to anti-inflammatory properties of L. reuteri, and found that testicular mass and other indicators typical of old age were similarly restored to youthful levels using systemic administration of antibodies blocking pro-inflammatory cytokine interleukin-17A. This indicated that uncontrolled host inflammatory responses contributed to the testicular atrophy phenotype in aged mice. Reduced circulating testosterone levels have been implicated in many adverse effects; dietary L. reuteri or other probiotic supplementation may provide a viable natural approach to prevention of male hypogonadism, absent the controversy and side-effects of traditional therapies, and yield practical options for management of disorders typically associated with normal aging. These novel findings suggest a potential high impact for microbe therapy in public health by imparting hormonal and gonad features of reproductive fitness typical of much younger healthy individuals.     

Effects of chemotactic factors and other agents on the amounts of actin and a 65,000-mol-wt protein associated with the cytoskeleton of rabbit and human neutrophils

Stimulation of rabbit neutrophils by the chemotactic factors fMet-Leu-Phe and leukotriene B4, by platelet activating factor, or by arachidonic acid produces a rapid and dose-dependent increase in the amounts of actin and of a 65,000-mol-wt protein associated with the cytoskeleton. Phorbol 12-myristate, 13-acetate, the calcium ionophore A23187 in the presence or absence of EGTA, and the fluorescent calcium chelator quin-2 also cause an increase in cytoskeletal actin. The stimulated increases in the cytoskeletal actin are not dependent on a rise in the intracellular concentration of free calcium and are not mediated by an increase in the intracellular pH or activation of protein kinase C. The increases in the cytoskeletal actin produced by fMet-Leu-Phe and leukotriene B4, but not by phorbol 12-myristate, 13-acetate, are inhibited by high osmolarity. The effect of hyperosmolarity requires a decrease in cell volume, is not mediated by an increase in basal intracellular concentration of free calcium, and is not prevented by pretreating the cells with amiloride. Preincubation of the cells with hyperosmotic solution also inhibits degranulation produced by all the stimuli tested. The inhibitory action of high osmolarity on the fMet-Leu-Phe and leukotriene B4 induced stimulation of cytoskeletal actin is discussed in terms of the possibility that the addition of high osmolarity, either directly or through activation of protein kinase C, causes receptor uncoupling.     

Characterization of the iron-containing superoxide dismutase and its response to stress in cyanobacterium Spirulina (Arthrospira) platensis

Superoxide dismutase (SOD) is considered a primary antioxidant which defends against reactive oxygen species that are induced by environmental stress. In this study, we examined changes in SOD activity and expression in the cyanobacterium Spirulina (Arthrospira) platensis under iron and salinity stress; we characterized its induction under these stress conditions and we overexpressed the enzyme in a bacterial host for preliminary characterization. Analysis of SOD isoforms concludes that S. platensis was found to regulate only the iron-containing SOD isoform (FeSOD) in response to two types of stress that were tested. The FeSOD expression (on the level of both mRNA and enzyme activity) was induced by the stress conditions of salinity and iron levels. The FeSOD from S. platensis was overexpressed in Escherichia coli BL21. The recombinant FeSOD protein (about 23 kDa) was purified for characterization. It showed high specific activity and pH stability at 6.0–9.0, and it is relatively thermostable, retaining 45 % of its activity after 30 min at 90 °C. Phylogenetic analysis reveals that S. platensis FeSOD is grouped with the FeSODs from other cyanobacterial species and separated from those of the eukaryotic Chlorophyta, suggesting that the FeSOD gene may be used as a molecular marker in physiological, phylogenetic, and taxonomic studies. This study also suggests that the increased activity and expression of SOD may play a role in algal survival under stress conditions.     

Phytochemical and mycological investigation ofArtemisia monosperma

Both polar and nonpolar fractions ofArtemisia monosperma were found to contain taraxasterol, taraxasterol acetate, pseudotaraxasterol acetate, lupeol, β-sitosterol and 3′,5-dihydroxy-4′,6,7-trimethoxyflavone. None of the isolated compounds except 3′,5-dihydroxy-4′,6,7-trimethoxyflavone provided successful control againstRhizoctonia damping-off of cotton in a greenhouse experiment when used as seed treatment. However, on evaluation ofA. monosperma dried shoot as amendment on controlling soil-borne plant pathogens, it was effective in decreasing the damping-off disease of cotton caused byRhizoctonia solani and provided a firmer plant stand. Higher doses of amendment (2 and 4%) caused a significant drop in the number of propagules ofR. solani in soil when incorporated 3 and 6 weeks before planting. In most cases incorporation ofA. monosperma in the soil caused a distinct increase in the total fungal population.In vitro studies showed toxicity of diffused or extracted substances fromA. monosperma for growth and pectolytic and cellulolytic enzyme activities of the target pathogen.     

Association between Polymorphism of the Vitamin D Metabolism Gene CYP27B1 and HLA-B27-Associated Uveitis. Is a State of Relative Immunodeficiency Pathogenic in HLA B27-Positive Uveitis?

Objective

Polymorphisms of the vitamin D metabolism gene CYP27B1 showed associations with multiple autoimmune diseases. The aim of this study was to investigate a possible association between the rs703842 A>G polymorphism of the CYP27B1 gene and HLA-B27-associated uveitis.

Design

One hundred fifty-nine patients with HLA-B27-associated uveitis, 138 HLA-B27-negative controls and 100 HLA-B27-positive controls were recruited for this retrospective case-control study. Main outcome parameters were genotype distribution and allelic frequencies determined by polymerase chain reaction.

Results

Carriers of the rs703842G allele were found significantly more often in patients with HLA-B27-associated uveitis than in HLA-B27-positive controls (p = 0.03). Between patients and HLA-B27-negative controls no significant difference in the genotype distribution of the rs703842 A>G polymorphism was found (p = 0.97).

Conclusions

Our data suggest that the rs703842 A>G polymorphism may play a role in HLA-B27-associated uveitis.