Protein-tyrosine phosphatase 1B (PTP1B) deficiency confers resistance to transforming growth factor-β (TGF-β)-induced suppressor effects in hepatocytes

Transforming growth factor-β (TGF-β) plays a dual role in hepatocytes, mediating both tumor suppressor and promoter effects. The suppressor effects of the cytokine can be negatively regulated by activation of survival signals, mostly dependent on tyrosine kinase activity. The aim of our work was to study the role of the protein-tyrosine phosphatase 1B (PTP1B) on the cellular responses to TGF-β, using for this purpose immortalized neonatal hepatocytes isolated from both PTP1B(+/+) and PTP1B(-/-) mice. We have found that PTP1B deficiency conferred resistance to TGF-β suppressor effects, such as apoptosis and growth inhibition, correlating with lower Smad2/Smad3 activation. Both responses were recovered in the presence of the general tyrosine kinase inhibitor genistein. PTP1B(-/-) cells showed elevated NF-κB activation in response to TGF-β. Knockdown of the NF-κB p65 subunit increased cell response in terms of Smads phosphorylation and apoptosis. Interestingly, these effects were accompanied by inhibition of Smad7 up-regulation. In addition, lack of PTP1B promoted an altered NADPH oxidase (NOX) expression pattern in response to TGF-β, strongly increasing the NOX1/NOX4 ratio, which was reverted by genistein and p65 knockdown. Importantly, NOX1 knockdown inhibited nuclear translocation of p65, promoted Smad phosphorylation, and decreased Smad7 levels. In summary, our results suggest that PTP1B deficiency confers resistance to TGF-β through Smad inhibition, an effect that is mediated by NOX1-dependent NF-κB activation, which in turn, increases the level of the Smad inhibitor Smad7 and participates in a positive feedback loop on NOX1 up-regulation.     

Two GacA-dependent small RNAs modulate the quorum-sensing response in Pseudomonas aeruginosa

In Pseudomonas aeruginosa, the GacS/GacA two-component system positively controls the quorum-sensing machinery and the expression of extracellular products via two small regulatory RNAs, RsmY and RsmZ. An rsmY rsmZ double mutant and a gacA mutant were similarly impaired in the synthesis of the quorum-sensing signal N-butanoyl-homoserine lactone, the disulfide bond-forming enzyme DsbA, and the exoproducts hydrogen cyanide, pyocyanin, elastase, chitinase (ChiC), and chitin-binding protein (CbpD). Both mutants showed increased swarming ability, azurin release, and early biofilm development.     

Cytoprotective Effect of <Emphasis Type="Italic">Valeriana officinalis</Emphasis> Extract on an In Vitro Experimental Model of Parkinson Disease

Parkinson′s disease (PD) is one of the most important neurodegenerative worldwide disorders. The potential cytoprotective effects of aqueous extract of Valeriana officinalis on rotenone-induced apoptosis in human neuroblastoma SH-SY5Y cells were demonstrated. The cytotoxicity, cell viability and analysis of cellular morphology were performed by MTT-tetrazole (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and phase contrast microscopy, respectively. Significant changes in the cellular morphology, and condensation of the cell body could be observed when cells were treated with 300 nM rotenone for 48 h. Three different concentrations of Valeriana officinalis extract were used (0.049, 0.098 and 0.195 mg/mL). These extracts brought about an increase of 7.0 ± 1.3%, 14.5 ± 1.3% and 14.5 ± 3.2% in cell viability. Our results indicated that neuroprotector action of the Valeriana officinalis extract provides support for later studies as they help understanding this drug for the development of cytoprotective various therapies in PD.     

High concentration of kynurenic acid in bile and pancreatic juice

Kynurenic acid (KYNA) is an agonist of the G-protein-coupled receptor GPR35, which is predominantly expressed in gastrointestinal tissues. The aim of this study was to determine the content of KYNA in gastric juice, bile and pancreatic juice and intestinal content. KYNA was determined by means of high performance liquid chromatography. The mean concentrations of KYNA in human gastric juice is 9.91 ± 0.71 nM in contrast to human bile (832.5 ± 204.1 and 306.8 ± 35.2 nM) obtained from patients with cholecystolithiasis and obstructive jaundice, respectively. In pigs, the KYNA levels in bile and pancreatic juice are 1,113.3 ± 63.34 and 757.0 ± 394.4 nM, respectively. The KYNA concentration increases along the digestive system, reaching 1,638 nM in the colon content. We suggest that the liver and pancreas affect the content of kynurenic acid in the lumen of the digestive tract.     

Diethylthiophosphate and diethyldithiophosphate induce genotoxicity in hepatic cell lines when activated by further biotransformation via Cytochrome P450

Organophosphorous (OP) compounds are the most commonly used pesticides. There are several published reports on the direct toxicity of OP pesticides, but few data on the toxicity of their metabolites. To determine if diethylthiophosphate (DETP) and diethyldithiophosphate (DEDTP), two of the major OP metabolites, demonstrate genotoxicity, and to elucidate the possible genotoxic mechanisms, we treated WRL68, HepG2, HeLa and human blood cells with different concentrations of DETP and DEDTP. We evaluated the possible contribution of oxidative stress generation and P450 enzymes to the genotoxicity of the OP metabolites, as determined using the comet assay. Our results showed that both OP metabolites (DETP and DEDTP) induce DNA damage only in the hepatic cell lines, and this effect could be related to a secondary non-diffusible metabolite generated by the activity of P450 enzymes since P450 enzyme inhibitors also inhibited the induction of DNA damage in hepatic cells. These secondary metabolites should be taken into account when assessing risk to human populations exposed to OP pesticides.     

Strains nodulating Lupinus albus on different continents belong to several new chromosomal and symbiotic lineages within Bradyrhizobium

In this work we analysed different chromosomal and symbiotic markers in rhizobial strains nodulating Lupinus albus (white lupin) in several continents. Collectively the analysis of their rrs and atpD genes, and 16S-23S intergenic spacers (ITS), showed that they belong to at least four chromosomal lineages within the genus Bradyrhizobium. Most isolates from the Canary Islands (near to the African continent) grouped with some strains isolated on mainland Spain and were identified as Bradyrhizobium canariense. These strains are divided into two ITS subgroups coincident with those previously described from isolates nodulating Ornithopus. The remaining strains isolated on mainland Spain grouped with most isolates from Chile (American continent) forming a new lineage related to Bradyrhizobium japonicum. The strains BLUT2 and ISLU207 isolated from the Canary Islands and Chile, respectively, formed two new lineages phylogenetically close to different species of Bradyrhizobium depending on the marker analyzed. The analysis of the nodC gene showed that all strains nodulating L. albus belong to the biovar genistearum; nevertheless they form four different nodC lineages of which lineage C is at present exclusively formed by L. albus endosymbionts isolated from different continents.     

Non weaving spiders on native woodlands and <Emphasis Type="Italic">Eucalyptus</Emphasis> plantations in Western Mexico: diversity and distribution patterns

Eucalyptus spp. are commonly planted, forming non-native plantations, including the tropics and their wildlife conservation value is relatively unknown. Recent studies have concluded that secondary forests and tree plantations are less diverse than well-developed tropical rain forests. However, introduced Eucalyptus stands harbored similar species richness to surrounding native woodland in temperate woodlands in North America though the identity of the species present may differ. Species composition, as well as dominance curves and differences in community structure add additional insight to understanding faunistic responses to replacement of native woodland by Eucalyptus plantations. Here, we compared species richness, diversity patterns, and the distribution of non-weaving spiders between native woodlands and Eucalyptus plantations in a temperate region of Mexico. We found more Lycosidae species in all plantation stands. Other community attributes were not consistently different between plantations and native woodlands. This is explained by similarities between, and differences within, the understory of the two main vegetation types. Multivariate analyses identified three spider groups and five spider species could be identified as indicators of these groups. A comparison of the number of species of the wandering spiders between the two vegetation types suggests a compensation pattern that is reported here for the first time.