Putative metabolic pathway of mannitol and sorbitol and in sugarcane

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A study of the hydrolysis pathway in oxalic acid catalyzed reacting TMOS-water mixtures under ultrasound stimulation

The hydrolysis of TMOS in oxalic acid catalyzed reacting TMOS-water mixtures, under ultrasound stimulation, was studied by fitting a simplified dissolution and reaction modeling for samples, the hydrolysis rate of which had been measured in a previous work. The reaction pathway represented in a ternary diagram shows a heterogeneous step for the reaction which gradually progresses until complete homogenization of the system. Besides the water dissolved due to the homogenizing effect of the alcohol, ultrasound maintains a virtual and additional dissolution of water located at the interface between the TMOS and water during the heterogeneous step of the reaction. The mean radius of the heterogeneity represented by water dispersed in TMOS was evaluated as around 150 Angstrom. The oxalic acid concentration accordingly increases the hydrolysis rate constant but its fundamental role on the solubility of water in TMOS could not unequivocally be established.

Downregulation of nuclear factor-kappa B (NF-kappa B) pathway by silibinin in human monocytes challenged with Paracoccidioides brasiliensis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Testicular ultrastructure and morphology of the seminal pathway in Prochilodus scrofa

The seminiferous tubules of Prochilodus scrofa present a coiled morphological arrangement with intertubular anastomoses and unrestricted spermatogonial distribution. The structural pattern of the seminiferous tubules is cystic, with cysts formed by cytoplasmic prolongations of Sertoli cells. Inside the cysts are observed different types of germ cells. The seminiferous tubules open individually on the ventral surface of the main testicular duct present in each testis. Each main testicular duct prolongs as a spermatic duct, fusing with the spermatic duct of the opposite side to form the common spermatic duct which opens into the urogenital papilla. The mature sperm cysts break and extravasate their content into the lumen of the seminiferous tubules from which the seminal fluid and the spermatozoa penetrate the main testicular duct, the spermatic duct and the common spermatic duct for semen ejaculation.

The post-transcriptional gene silencing pathway in Eucalyptus

Post-transcriptional gene silencing (PTGS) is a conserved surveillance mechanism that identifies and cleaves double-stranded RNA molecules and their cellular cognate transcripts. The RNA silencing response is actually used as a powerful technique (named RNA interference) for potent and specific inhibition of gene expression in several organisms. To identify gene products in Eucalyptus sharing similarities with enzymes involved in the PTGS pathway, we queried the expressed sequence tag database of the Brazilian Eucalyptus Genome Sequence Project Consortium (FORESTs) with the amino acid sequences of known PTGS-related proteins. Among twenty-six prospected genes, our search detected fifteen assembled sequences encoding products presenting high level of similarity (E value < 10 -40) to proteins involved in PTGS in plants and other organisms. We conclude that most of the genes known to be involved in the PTGS pathway are represented in the FORESTs database. Copyright by the Brazilian Society of Genetics.

Temporal evolution of sulfated zirconia sol-gel during dip coating: Analysis of mass drainage with time-varying refractive index

The formation of sulfated zirconia films from a sol-gel derived aqueous suspension is subjected to double-optical monitoring during batch dip coating. Interpretation of interferometric patterns, previously obscured by a variable refractive index, is now made possible by addition of its direct measurement by a polarimetric technique in real time. Significant sensitivity of the resulting physical thickness and refractive index curves (uncertainties of ±7 nm and ±0.005, respectively) to temporal film evolution is shown under different withdrawal speeds. As a first contribution to quantitative understanding of temporal film formation with varying nanostructure during dip coating, detailed analysis is directed to the stage of the process dominated by mass drainage, whose simple modeling with temporal t-1/2 dependence is verified experimentally. © 2006 Elsevier B.V. All rights reserved.

Acute toxicity of waters from the urban drainage channels of Santos (São Paulo, Brazil)

The objective of this study was to evaluate the toxicity of water which flows toward the beaches of Santos, SP, Brazil. Water samples were collected from eight urban drainage channels and a small creek, in March, April and August 2005. For each sample, some physical-chemical parameters were analyzed: pH, dissolved oxygen, temperature, salinity, presence of free chlorine and total ammonia contents. Acute toxicity tests (48h) with Daphnia similis were also performed with the samples. The level of ammonia was relatively high in the majority of the samples (≥ 1.5 mg/L), and free chlorine was measurable in most of them. Acute toxicity was observed in four water samples (stations 3, 4, 5 and 7), at least in one occasion. The toxicity was positively correlated with the ammonia concentrations and salinity. Because acute toxicity was detected, actions aiming to control the pollution sources and improve the water quality are recommended.

SKPDB: A structural database of shikimate pathway enzymes

Background: The functional and structural characterisation of enzymes that belong to microbial metabolic pathways is very important for structure-based drug design. The main interest in studying shikimate pathway enzymes involves the fact that they are essential for bacteria but do not occur in humans, making them selective targets for design of drugs that do not directly impact humans.Description: The ShiKimate Pathway DataBase (SKPDB) is a relational database applied to the study of shikimate pathway enzymes in microorganisms and plants. The current database is updated regularly with the addition of new data; there are currently 8902 enzymes of the shikimate pathway from different sources. The database contains extensive information on each enzyme, including detailed descriptions about sequence, references, and structural and functional studies. All files (primary sequence, atomic coordinates and quality scores) are available for downloading. The modeled structures can be viewed using the Jmol program.Conclusions: The SKPDB provides a large number of structural models to be used in docking simulations, virtual screening initiatives and drug design. It is freely accessible at http://lsbzix.rc.unesp.br/skpdb/. © 2010 Arcuri et al; licensee BioMed Central Ltd.

Infliximab prevents increased systolic blood pressure and upregulates the AKT/eNOS pathway in the aorta of spontaneously hypertensive rats

High systolic blood pressure caused by endothelial dysfunction is a comorbidity of metabolic syndrome that is mediated by local inflammatory signals. Insulin-induced vasorelaxation due to endothelial nitric oxide synthase (eNOS) activation is highly dependent on the activation of the upstream insulin-stimulated serine/threonine kinase (AKT) and is severely impaired in obese, hypertensive rodents and humans. Neutralisation of circulating tumor necrosis factor-α (TNFα) with infliximab improves glucose homeostasis, but the consequences of this pharmacological strategy on systolic blood pressure and eNOS activation are unknown. To address this issue, we assessed the temporal changes in the systolic pressure of spontaneously hypertensive rats (SHR) treated with infliximab. We also assessed the activation of critical proteins that mediate insulin activity and TNFα-mediated insulin resistance in the aorta and cardiac left ventricle. Our data demonstrate that infliximab prevents the upregulation of both systolic pressure and left ventricle hypertrophy in SHR. These effects paralleled an increase in AKT/eNOS phosphorylation and a reduction in the phosphorylation of inhibitor of nuclear factor-κB (Iκβ) and c-Jun N-terminal kinase (JNK) in the aorta. Overall, our study revealed the cardiovascular benefits of infliximab in SHR. In addition, the present findings further suggested that the reduction of systolic pressure and left ventricle hypertrophy by infliximab are secondary effects to the reduction of endothelial inflammation and the recovery of AKT/eNOS pathway activation. © 2012 Elsevier B.V.

Hepatitis C Virus NS2 Protein Inhibits DNA Damage Pathway by Sequestering p53 to the Cytoplasm

Chronic hepatitis C virus (HCV) infection is an important cause of morbidity and mortality globally, and often leads to end-stage liver disease. The DNA damage checkpoint pathway induces cell cycle arrest for repairing DNA in response to DNA damage. HCV infection has been involved in this pathway. In this study, we assess the effects of HCV NS2 on DNA damage checkpoint pathway. We have observed that HCV NS2 induces ataxia-telangiectasia mutated checkpoint pathway by inducing Chk2, however, fails to activate the subsequent downstream pathway. Further study suggested that p53 is retained in the cytoplasm of HCV NS2 expressing cells, and p21 expression is not enhanced. We further observed that HCV NS2 expressing cells induce cyclin E expression and promote cell growth. Together these results suggested that HCV NS2 inhibits DNA damage response by altering the localization of p53, and may play a role in the pathogenesis of HCV infection. © 2013 Bitter et al.

A metabolic pathway assembled by enzyme selection may support herbivory of leaf-cutter ants on plant starch

Mutualistic associations shape the evolution in different organism groups. The association between the leaf-cutter ant Atta sexdens and the basidiomycete fungus Leucoagaricus gongylophorus has enabled them to degrade starch from plant material generating glucose, which is a major food source for both mutualists. Starch degradation is promoted by enzymes contained in the fecal fluid that ants deposit on the fungus culture in cut leaves inside the nests. To understand the dynamics of starch degradation in ant nests, we purified and characterized starch degrading enzymes from the ant fecal fluid and from laboratory cultures of L. gongylophorus and found that the ants intestine positively selects fungal α-amylase and a maltase likely produced by the ants, as a negative selection is imposed to fungal maltase and ant α-amylases. Selected enzymes are more resistant to catabolic repression by glucose and proposed to structure a metabolic pathway in which the fungal α-amylase initiates starch catalysis to generate byproducts which are sequentially degraded by the maltase to produce glucose. The pathway is responsible for effective degradation of starch and proposed to represent a major evolutionary innovation enabling efficient starch assimilation from plant material by leaf-cutters. © 2013 Elsevier Ltd.