Modifications in muscarinic, dopaminergic and serotonergic receptors concentrations in the hippocampus and striatum of epileptic rats

The present study was undertaken in order to investigate the muscarinic (M(1)), dopaminergic (D(1) and D(2)) and serotonergic (5-HT(2)) receptors densities in hippocampus and striatum of Wistar rats after status epilepticus (SE) induced by pilocarpine. The control group was treated with 0.9% saline. An other group of rats received pilocarpine (400 mg/kg, s.c.) and both groups were sacrificed 1 h after treatment. The results have shown that pilocarpine administration and resulting SE produced a downregulation of M(1) receptor in hippocampus (41%) and striatum (51%) and an increase in the dissociation constant (K(d)) values in striatum (42%) alone. In both areas the 5-HT(2) receptor density remained unaltered, but a reduction (50%) and an increase (15%) in the K(d) values were detected in striatum and hippocampus, respectively. D(1) and D(2) receptor densities in hippocampus and striatum remained unaltered meanwhile K(d) values for D(1) receptor declined significantly, 33% in hippocampus and 26% in striatum. Similarly, K(d) values for D(2) decreased 55% in hippocampus and 52% in striatum. From the preceding results, it is clear that there is a possible relation between alterations in muscarinic receptor density and others systems studied as well as they suggest that changes in dissociation constant can be responsible for the establishment of pilocarpine-induced SE by altering the affinity of neurotransmitters such as acetylcholine, dopamine and serotonine.     

The use of waste biomass of Sargassum sp. for the biosorption of copper from simulated semiconductor effluents

Seaweed Sargassum sp. biomass proved to be useful for the recovery of ionic copper from highly concentrated solutions simulating effluents from semiconductor production. In the case of solutions containing copper in the form of chloride, sulphate and nitrate salts, the best pH for the recovery of copper was 4.5. It was observed that copper biosorption from copper nitrate solutions was higher than the recovery of copper from copper chloride or sulphate solutions. The continuous system used was constituted of four column reactors filled with the biomass of Sargassum sp. and showed high operational stability. Biomass of Sargassum sp. in the reactors was gradually saturated from the bottom to the top of each column reactor. The biomass of Sargassum sp. in the first column was saturated first, followed by a gradual saturation of the remaining columns due to the pre-concentration caused by the biomass in the first column. The biomass of Sargassum in the bioreactors completely biosorbed the ionic copper contained in 63 L of copper sulphate solution, 72 L of copper chloride solution and 72 L of copper nitrate solution, all the solutions containing copper at 500 mg/L. Effluents produced after biosorption presented copper concentrations less than 0.5 mg/L.     

Recombinant Cdt1 induces rereplication of G2 nuclei in Xenopus egg extracts

A crucial regulation for maintaining genome integrity in eukaryotes is to limit DNA replication in S phase to only one round. Several models have been proposed; one of which, the licensing model, predicted that formation of the nuclear membrane restricts access to chromatin to a positive replication factor. Cdt1, a factor binding to origins and recruiting the MCM2-7 helicase, has been identified as a component of the licensing system in Xenopus and other eukaryotes. Nevertheless, evidence is missing demonstrating a direct role for unscheduled Cdt1 expression in promoting illegitimate reinitiation of DNA synthesis. We show here that Xenopus Cdt1 is absent in G2 nuclei, suggesting that it might be either degraded or exported. Recombinant Cdt1, added to egg extracts in G2, crosses the nuclear membrane, binds to chromatin, and relicenses the chromosome for new rounds of DNA synthesis in combination with chromatin bound Cdc6. The mechanism involves rebinding of MCM3 to chromatin. Reinitiation is blocked by geminin only in G2 and is not stimulated by Cdc6, demonstrating that Cdt1, but not Cdc6, is limiting for reinitiation in egg extracts. These results suggest that removal of Cdt1 from chromatin and its nuclear exclusion in G2 is critical in regulating licensing and that override of this control is sufficient to promote illegitimate firing of origins.     

Relations Between River Plant Richness in the Portuguese Floodplains and the Widespread Water Knotgrass <Emphasis Type="Italic">(Paspalum Paspalodes</Emphasis>)

We examined the variability of macroinvertebrate assemblage structure, species identities, and functional feeding group composition in relation to stream size, tributary position, and in-stream factors in a boreal watershed in Finland. Our study included three riffle sites in each of three stream sections in each of three stream size classes. Multi-response permutation procedure, indicator value method, and canonical correspondence analysis revealed clear differences in assemblage structure among the stream size classes, with a gradual increase of species richness as the stream size increased. Significant differences in assemblage structure were also found among the tributary river systems. The functional feeding group composition broadly followed the river continuum concept, i.e., headwaters were dominated by shredders, gatherers, or filterers, whereas scrapers increased in relative abundance with stream size. There was, however, considerable variation in the functional feeding group composition both among and within the headwater stream sections. Our findings refer to a strong influence of stream size on macroinvertebrate assemblages, but also factors prevailing at the scale of individual riffles should be considered in biodiversity conservation of lotic ecosystems.     

Leptin, from fat to inflammation: old questions and new insights

Leptin is 16 kDa adipokine that links nutritional status with neuroendocrine and immune functions. Initially thought to be a satiety factor that regulates body weight by inhibiting food intake and stimulating energy expenditure, leptin is a pleiotropic hormone whose multiple effects include regulation of endocrine function, reproduction, and immunity. Leptin can be considered as a pro-inflammatory cytokine that belongs to the family of long-chain helical cytokines and has structural similarity with interleukin-6, prolactin, growth hormone, IL-12, IL-15, granulocyte colony-stimulating factor and oncostatin M. Because of its dual nature as a hormone and cytokine, leptin links the neuroendocrine and the immune system. The role of leptin in the modulation of immune response and inflammation has recently become increasingly evident. The increase in leptin production that occurs during infection and inflammation strongly suggests that leptin is a part of the cytokine network which governs the inflammatory-immune response and the host defense mechanisms. Leptin plays an important role in inflammatory processes involving T cells and has been reported to modulate T-helper cells activity in the cellular immune response. Several studies have implicated leptin in the pathogenesis of autoimmune inflammatory conditions, such as experimental autoimmune encephalomyelitis, type 1 diabetes, rheumatoid arthritis, and intestinal inflammation. Very recently, a key role for leptin in osteoarthritis has been demonstrated: leptin indeed exhibits, in concert with other pro-inflammatory cytokines, a detrimental effect on articular cartilage by promoting nitric oxide synthesis in chondrocytes. Here, we review the recent advances regarding leptin biology with a special focus on those actions relevant to the role of leptin in the pathophysiology of inflammatory processes and immune responses.     

Hypertriglyceridemia in lecithin-cholesterol acyltransferase-deficient mice is associated with hepatic overproduction of triglycerides, increased lipogenesis, and improved glucose tolerance

Lecithin-cholesterol acyltransferase deficiency is frequently associated with hypertriglyceridemia (HTG) in animal models and humans. We investigated the mechanism of HTG in the ldlr-/- x lcat-/- (double knockout (dko)) mice using the ldlr-/- x lcat+/+ (knock-out (ko)) littermates as control. Mean fasting triglyceride (TG) levels in the dko mice were elevated 1.75-fold compared with their controls (p < 0.002). Both the very low density lipoprotein and the low density lipoprotein/intermediate density lipoprotein fractions separated by fast protein liquid chromatography were TG-enriched in the dko mice. In vitro lipolysis assay revealed that the dko mouse very low density lipoprotein (d < 1.019 g/ml) fraction separated by ultracentrifugation was a more efficient substrate for lipolysis by exogenous bovine lipoprotein lipase. Post-heparin lipoprotein lipase activity was reduced by 61% in the dko mice. Hepatic TG production rate, determined after intravenous Triton WR1339 injection, was increased 8-fold in the dko mice. Hepatic mRNA levels of sterol regulatory element binding protein-1 (srebp-1) and its target genes acetyl-CoA carboxylase-1 (acc-1), fatty acid synthase (fas), and stearoyl-CoA desaturase-1 (scd-1) were significantly elevated in the dko mice compared with the ko control. The hepatic mRNA levels of LXRalpha (lxralpha) and its target genes including angiopoietin-like protein 3 (angptl-3) in the dko mice were unchanged. Fasting glucose and insulin levels were reduced by 31 and 42%, respectively in the dko mice, in conjunction with a 49% reduction in hepatic pepck-1 mRNA (p = 0.014). Both the HTG and the improved fasting glucose phenotype seen in the dko mice are at least in part attributable to an up-regulation of the hepatic srebp-1c gene.     

Microscopic and macroscopic study of the interaction betweenAlternaria alternata (Fr.) Keissler andNigrospora oryzae (Berk. & Broome) Petch.

Light Microscopy and Cryo-Scanning Electron Microscopy techniques were used to analyse the interaction betweenAlternaria alternata andNigrospora oryzae at different temperatures (15 and 25°C) and water activities (0.85, 0.90, 0.95, 0.98 and 0.995). Each interaction was given a numerical value to obtain the Index of Dominance (I) based on the variations observed in fungus growth when the environmental conditions changed. For a better understanding of the process, each species was studied individually anysing the effects of abiotic and biotic factors on their growth. In the tests performed, none of the two fungus species analysed was dominant over the other since both species presented mutual intermingling both in Rice Extract agar and in rice grains and no interaction between hyphae and the reproductive structures was observed.Alternaria alternata andN. oryzae presented their highest growth both individually and dually at 0.995 water activity and 25°CAlternaria alternata sporulated at all temperatures and water activity values, except at 0.85, whereasN. oryzae sporulated only at 0.98 and 0.995 at 25°C, presenting no changes as the strains interacted. Finally, temperature and water activity significantly affected fungal growth.     

Hog1 mitogen-activated protein kinase plays conserved and distinct roles in the osmotolerant yeast Torulaspora delbrueckii

Torulaspora delbrueckii has emerged during evolution as one of the most osmotolerant yeasts. However, the molecular mechanisms underlying this unusual stress resistance are poorly understood. In this study, we have characterized the functional role of the high-osmolarity glycerol (HOG) mitogen-activated protein kinase pathway in mediating the osmotic stress response, among others, in T. delbrueckii. We show that the T. delbrueckii Hog1p homologue TdHog1p is phosphorylated after cell transfer to NaCl- or sorbitol-containing medium. However, TdHog1p plays a minor role in tolerance to conditions of moderate osmotic stress, a trait related mainly with the osmotic balance. In consonance with this, the absence of TdHog1p produced only a weak defect in the timing of the osmostress-induced glycerol and GPD1 mRNA overaccumulation. Tdhog1Delta mutants also failed to display aberrant morphology changes in response to osmotic stress. Furthermore, our data indicate that the T. delbrueckii HOG pathway has evolved to respond to specific environmental conditions and to play a pivotal role in the stress cross-protection mechanism.