A kinetic spectrophotometric method for simultaneous determination of glycine and lysine by artificial neural networks

A spectrophotometric method for simultaneous analysis of glycine and lysine is proposed by application of neural networks on the spectral kinetic data. The method is based on the reaction of glycine and lysine with 1,2-naphthoquinone-4-sulfonate (NQS) in slightly basic medium. On the basis of the difference in the rate between the two reactions, these two amino acids can be determined simultaneously in binary mixtures. Feed-forward neural networks have been trained to quantify considered amino acids in mixtures under optimum conditions. In this way, a one-layer network was trained. Sigmoidal and linear transfer functions were used in the hidden and output layers, respectively. Linear calibration graphs were obtained in the concentration range of 1 to 25microgml(-1) for glycine and 1 to 19microgml(-1) for lysine. The analytical performance of this method was characterized by the relative standard error. The proposed method was applied to the determination of considered amino acids in synthetic samples.     

Homozygosity mapping in consanguineous families reveals extreme heterogeneity of non-syndromic autosomal recessive mental retardation and identifies 8 novel gene loci

Autosomal recessive gene defects are arguably the most important, but least studied genetic causes of severe cognitive dysfunction. Homozygosity mapping in 78 consanguineous Iranian families with nonsyndromic autosomal recessive mental retardation (NS-ARMR) has enabled us to determine the chromosomal localization of at least 8 novel gene loci for this condition. Our data suggest that in the Iranian population NS-ARMR is very heterogeneous, and they argue against the existence of frequent gene defects that account for more than a few percent of the cases. Mohammad Mahdi Motazacker and Masoud Garshasbi have contributed equally to this work.     

Chromothripsis in Healthy Individuals Affects Multiple Protein-Coding Genes and Can Result in Severe Congenital Abnormalities in Offspring

Chromothripsis represents an extreme class of complex chromosome rearrangements (CCRs) with major effects on chromosomal architecture. Although recent studies have associated chromothripsis with congenital abnormalities, the incidence and pathogenic effects of this phenomenon require further investigation. Here, we analyzed the genomes of three families in which chromothripsis rearrangements were transmitted from a mother to her child. The chromothripsis in the mothers resulted in completely balanced rearrangements involving 8–23 breakpoint junctions across three to five chromosomes. Two mothers did not show any phenotypic abnormalities, although 3–13 protein-coding genes were affected by breakpoints. Unbalanced but stable transmission of a subset of the derivative chromosomes caused apparently de novo complex copy-number changes in two children. This resulted in gene-dosage changes, which are probably responsible for the severe congenital phenotypes of these two children. In contrast, the third child, who has a severe congenital disease, harbored all three chromothripsis chromosomes from his healthy mother, but one of the chromosomes acquired de novo rearrangements leading to copy-number changes. These results show that the human genome can tolerate extreme reshuffling of chromosomal architecture, including breakage of multiple protein-coding genes, without noticeable phenotypic effects. The presence of chromothripsis in healthy individuals affects reproduction and is expected to substantially increase the risk of miscarriages, abortions, and severe congenital disease.     

Colonic microbiome is altered in alcoholism

Several studies indicate the importance of colonic microbiota in metabolic and inflammatory disorders and importance of diet on microbiota composition. The effects of alcohol, one of the prominent components of diet, on colonic bacterial composition is largely unknown. Mounting evidence suggests that gut-derived bacterial endotoxins are cofactors for alcohol-induced tissue injury and organ failure like alcoholic liver disease (ALD) that only occur in a subset of alcoholics. We hypothesized that chronic alcohol consumption results in alterations of the gut microbiome in a subgroup of alcoholics, and this may be responsible for the observed inflammatory state and endotoxemia in alcoholics. Thus we interrogated the mucosa-associated colonic microbiome in 48 alcoholics with and without ALD as well as 18 healthy subjects. Colonic biopsy samples from subjects were analyzed for microbiota composition using length heterogeneity PCR fingerprinting and multitag pyrosequencing. A subgroup of alcoholics have an altered colonic microbiome (dysbiosis). The alcoholics with dysbiosis had lower median abundances of Bacteroidetes and higher ones of Proteobacteria. The observed alterations appear to correlate with high levels of serum endotoxin in a subset of the samples. Network topology analysis indicated that alcohol use is correlated with decreased connectivity of the microbial network, and this alteration is seen even after an extended period of sobriety. We show that the colonic mucosa-associated bacterial microbiome is altered in a subset of alcoholics. The altered microbiota composition is persistent and correlates with endotoxemia in a subgroup of alcoholics.     

Maintenance of membrane integrity and increase of taxanes production in hazel (Corylus avellana L.) cells induced by low-intensity ultrasound

Suspension-cultured hazel cells were ultrasonicated at power densities of 4 and 455 mW for 4–40 min. Both treatments stimulated the production of major taxanes: Taxol, 10-deacetylbaccatin, and baccatin III. The highest amounts of these taxanes (0.46, 0.26, and 0.07 mg/l, respectively) were obtained at 8 and 20 min of the treatment at 455 mW. Ultrasound had no adverse effects on cell viability, growth, or membrane integrity. Increased release of taxanes by ultrasound resulted not from increased membrane permeability but more likely from stimulation of taxanes biosynthesis.     

Disruption of tubulin polymerization and cell proliferation by 1-naphthylarsonic acid

Arsenical compounds exhibit a differential toxicity to cancer cells. Microtubules are a primary target of a number of anticancer drugs, such as arsenical compounds. The interaction of 1-NAA (1-naphthylarsonic acid) has been investigated on microtubule polymerization under in vitro and cellular conditions. Microtubules were extracted from sheep brain. Transmission electron microscopy was used to show microtubule structure in the presence of 1-NAA. Computational docking method was applied for the discovery of ligand-binding sites on the microtubular proteins. Proliferation of HeLa cells and HF2 (human foreskin fibroblasts) was measured by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] assay method following their incubation with 1-NAA. Fluorescence microscopic labelling was done with the help of α-tubulin monoclonal antibody and Tunel kit was used to investigate the apoptotic effects of 1-NAA on the HeLa cells. 1-NAA inhibits the tubulin polymerization by the formation of abnormal polymers having high affinity to the inner cell wall.     

A Potential Association between Helicobacter pylori CagA EPIYA and Multimerization Motifs with Cytokeratin 18 Cleavage Rate during Early Apoptosis

Background and Aims: Helicobacter pylori is a highly diverse pathogen, which encounters epithelial cells as the initial defense barrier during its lifelong infection. The structure of epithelial cells can be disrupted through cleavage of microfilaments. Cytokeratin 18 (CK18) is an intermediate filament, the cleavage of which is considered an early event during apoptosis following activation of effector caspases. Methods: Helicobacter pylori strains were isolated from 76 dyspeptic patients. cagA 3’ variable region and CagA protein status were analyzed by PCR and western blotting, respectively. Eight hours post‐co‐culture of AGS cells with different H. pylori strains, flow cytometric analysis was performed using M30 monoclonal antibody specific to CK18 cleavage‐induced neo‐epitope. Results: Higher rates of CK18 cleavage were detected during co‐culture of AGS cells with H. pylori strains bearing greater numbers of cagA EPIYA‐C and multimerization (CM) motifs. On the other hand, H. pylori strains with greater numbers of EPIYA‐B relative to EPIYA‐C demonstrated a decrease in CK18 cleavage rate. Thus, H. pylori‐mediated cleavage of CK18 appeared proportional to the number of CagA EPIYA‐C and CM motifs, which seemed to be downplayed in the presence of EPIYA‐B motifs. Conclusions: Our observation associating the heterogeneity of cagA variants with the potential of H. pylori strains in the induction of CK18 cleavage as an early indication of apoptosis in gastric epithelial cells supports the fact that apoptosis may be a type‐specific trait. However, additional cagA‐targeted experiments are required to clearly identify the role of EPIYA and CM motifs in apoptosis and/or the responsible effector molecules.     

Remarkable nutritional diversity of basidiomycetes in the Corticiales, including a new foliicolous species of Marchandiomyces (anamorphic Basidiomycota, Corticiaceae) from Australia

Fungi in the basidiomycete order Corticiales are remarkably diverse nutritionally, including a variety of saprotrophs, plant and fungal pathogens, and lichen-forming fungi. Tracing the origin of this diversity depends on a clearer understanding of the phylogenetic relationships of fungi in the order. One of its core members is the genus Marchandiomyces, originally established for lichen pathogens that form orange or coral bulbils. We describe here a new species in the genus, M. marsonii sp. nov., which is unusual in its appearance, habit, and geographic provenance. It is foliicolous on leaves of Pandanus (screw pines, Pandanaceae) and produces flattened, coral bulbils resembling apothecia of the ascomycete genus Orbilia. It is also the first member of the genus to be collected from Australia. An isolate of the new fungus and several additional cultures of related plant pathogenic fungi were obtained and investigated phylogenetically using parsimony, likelihood, and Bayesian analyses of nuclear small and large subunit ribosomal sequences. Our phylogeny makes clear that Marchandiomyces species and their close relatives contribute significantly to the ecological diversity of the Corticiales and that this diversity is derived mainly from lignicolous ancestors.