Aminoacetone induces loss of ferritin ferroxidase and iron uptake activities

Aminoacetone (AA) is a threonine and glycine metabolite overproduced and recently implicated as a contributing source of methylglyoxal (MG) in conditions of ketosis. Oxidation of AA to MG, NH4+, and H

2

O

2

has been reported to be catalyzed by a copper-dependent semicarbazide sensitive amine oxidase (SSAO) as well as by copper- and iron ion-catalyzed reactions with oxygen. We previously demonstrated that AA-generated O2•al (AA

•

) induce dose-dependent Fe(II) release from horse spleen ferritin (HoSF); no reaction occurs under nitrogen. In the present study we further explored the mechanism of iron release and the effect of AA on the ferritin apoprotein. Iron chelators such as EDTA, ATP and citrate, and phosphate accelerated AA-promoted iron release from HoSF, which was faster in horse spleen isoferritins containing larger amounts of phosphate in the core. Incubation of apoferritin with AA (2.5-50 mM, after 6 h) changes the apoprotein electrophoretic behavior, suggesting a structural modification of the apoprotein by AA-generated ROS. Superoxide dismutase (SOD) was able to partially protect apoferritin from structural modification whereas catalase, ethanol, and mannitol were ineffective in protection. Incubation of apoferritin with AA (1-10 mM) produced a dose-dependent decrease in tryptophan fluorescence (13-30%, after 5 h), and a partial depletion of protein thiols (29% after 24 h). The AA promoted damage to apoferritin produced a 40% decrease in apoprotein ferroxidase activity and an 80% decrease in its iron uptake ability. The current findings of changes in ferritin and apoferritin may contribute to intracellular iron-induced oxidative stress during AA formation in ketosis and diabetes mellitus.     

Seroepidemiological markers of enterically transmitted viral hepatitis A and E in individuals living in a community located in the North Area of Rio de Janeiro,RJ, Brazil

We investigated the seroprevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) infection in subjects living in the community of Manguinhos, Rio de Janeiro, Brazil, and assisted at the Health Unit of Escola Nacional de Saúde Pública, Funda??o Oswaldo Cruz. After formal consent, individuals were submitted to an interview using a standardized questionnaire. Anti-HAV and anti-HEV antibodies were detected by ELISA. Statistical analysis was carried out using the Epi-Info 6.04b software, to investigate possible associations between serological markers and risk factors. Results were regarded as significant when p value < 0.05. Although a high prevalence of anti-HAV was observed (87%), almost 50% of subjects under the age of 10 were susceptible to HAV infection, an unexpected rate in endemic areas. This fact could be attributed to improvements in environmental sanitation, occurring in this area in the last years. The increasing proportion of susceptible people may result in outbreaks of HAV infection, since the virus still circulates in this area, as verified by the detection of anti-HAV IgM in some individuals. No statistical association was met between HAV infection and the risk factors here assessed. The anti-HEV IgG prevalence found in this population was 2.4%, consistent with the one found in non-endemic areas.     

The genomic structure,chromosomal localization,and analysis of SIL as a candidate gene for holoprosencephaly

Holoprosencephaly (HPE) is the most common congenital malformation of the brain and face in humans. In this study we report the analysis of SIL (Sumacr;CL iumacr;nterrupting lumacr;ocus) as a candidate gene for HPE. Fluorescent in situ hybridization (FISH) analysis using a BAC 246e16 confirmed the assignment of SIL to 1p32. Computational analysis of SIL at the protein level revealed a 73% overall identity between the human and murine proteins. Denaturing high performance liquid chromatography (dHPLC) techniques were used to screen for mutations and these studies identified several common polymorphisms but no disease-associated mutations, suggesting that SIL is not a common factor in HPE pathogenesis in humans.     

Leptin treatment during the neonatal period is associated with higher food intake and adult body weight in rats.

For this study, we have determined the effects of neonatal leptin treatment on the evolution of body weight. Experiment 1: pups were divided into two groups: LepF - injected with leptin (8 micro g/100 g of body weight) for the first 10 days of lactation and control (C) - receiving saline. Experiment 2: pups were divided into two groups: LepL - injected with the same leptin concentration of experiment one for the last 10 days of lactation, and C, which received saline. Body weight and food intake were monitored until age 150 days, after which leptin concentrations were measured by ELISA. The LepF group had a significant increase in body weight (p < 0.05) from day 98 onward, in food intake (p < 0.05) from day 74 onward, and higher serum leptin concentration compared to the control (108 %, p < 0.05). The LepL group had a significant increase in body weight (p < 0.05) from day 113 onward, in food intake from day 121 onward (p < 0.001), and higher serum leptin concentration compared to controls (6.9 %, p < 0.05). These results suggest that both periods of lactation constituted a critical window for body weight and food intake programming, but the effects are more marked when the leptin is injected within the first ten days.     

Exogenous salicylic acid alleviates water stress in watermelon plants

Salicylic acid (SA) has been considered to attenuate the effects of abiotic stresses on plants, including water deficit that intensely affects the growth and production of plants. The goal of this work was to evaluate the role of SA in the alleviation of water stress in watermelon seedlings on a morphophysiological and biochemical level. The experiment consisted of application of SA at concentrations of 0, 0.25, 0.50, 0.75 and 1.0 μmol L⁻¹ to leaves of watermelon seedlings grown in three levels of water retention (100%, 75% and 50% WRL). To evaluate the effect on morphophysiological and biochemical aspects, the plant height, leaf area, shoot and root dry weight, chlorophyll index, relative water content, electrolyte leakage, protein content, amino acids, proline, carbohydrates, sucrose and starch concentration variables were determined. All variables were influenced by the SA concentrations and WRL, with statistically significant interaction between these factors for all except root dry weight. SA promotes increases in the concentration of organic solutes and reduces the rate of electrolyte leakage in watermelon seedlings, thus, supporting metabolism and growth of plants under stress conditions resulting from water deficit.     

The neo-X neo-Y sex pair in Acrididae,its structure and association

In most of the fifty described cases of neo-X neo-Y sex determining systems in Acrididae the pairing regions during meiosis are limited to distal regions. A comparative study on the structure and pairing mechanisms of Dichroplus silveiraguidoi (2n=8); Dichroplus bergi (2n=22) and Dichroplus vittatus (2n=20) has been undertaken. — The sex bivalents of these three grasshoppers are different: the neo-X centromere is associated with the neo-Y telomere in D. silveiraguidoi; in D. bergi the neo-X is related through the short arm telomere to the centromere of neo-Y and both members of the sex pair are associated by the telomeres in D. vittatus. Centromeric and telomeric C-band positive blocks are present in both members of the pair in the three species. D. silveiraguidoi also presents an interstitial block in the neo-X. These blocks are brightly fluorescent with quinacrine mustard and Hoechst 33258 at low concentration (0.05 g/ml). The region of neo-X corresponding to the primitive X takes an intermediate staining during the early meiotic prophase with C-banding and Hoechst 33258. — The structure of the sex bivalent and the particular staining of the X region are discussed in relation to the available information on the presence of different types of DNA in this segment. The possibility that the neo-X interstitial block of D. silveiraguidoi plays a role in preventing the spreading of heterochromatinization along the chromosome is also discussed. The classical interpretation of the neo-X neo-Y association during meiotic prophase as the result of a terminalized chiasma is considered in the light of optic and electronmicroscopic data. Other possible mechanisms of relationship between both chromosomes are also presented by these three orthopteran species.     

Inhibition of creatine kinase activity from rat cerebral cortex by D-2-hydroxyglutaric acid in vitro

D-2-Hydroxyglutaric acid (DGA) is the biochemical hallmark of patients affected by the neurometabolic disorder known as D-2-hydroxyglutaric aciduria (DHGA). Although this disease is predominantly characterized by severe neurological findings, the underlying mechanisms of brain injury are virtually unknown. In the present study, we investigated the effect of DGA on total, cytosolic, and mitochondrial creatine kinase (CK) activities from cerebral cortex of 30-day-old Wistar rats. Total CK activity (tCK) was measured in whole cell homogenates, whereas cytosolic and mitochondrial activities were measured in the cytosolic and mitochondrial preparations from cerebral cortex. We verified that CK activities were significantly inhibited by DGA (11-34% inhibition) at concentrations as low as 0.25 mM, being the mitochondrial fraction the most affected activity. Kinetic studies revealed that the inhibitory effect of DGA was non-competitive in relation to phosphocreatine. We also observed that this inhibition was fully prevented by pre-incubation of the homogenates with reduced glutathione, suggesting that the inhibitory effect of DGA on tCK activity is possibly mediated by oxidation of essential thiol groups of the enzyme. Considering the importance of CK activity for brain metabolism homeostasis, our results suggest that inhibition of this enzyme by increased levels of DGA may be related to the neurodegeneration of patients affected by DHGA.     

Modeling of a bipedal robot using mutually coupled Rayleigh oscillators

The objective of the work presented here was the modeling of a bipedal robot using a central pattern generator (CPG) formed by a set of mutually coupled Rayleigh oscillators. We analyzed a 2D model, with the three most important determinants of gait, that performs only motions parallel to the sagittal plane. Using oscillators with integer relation of frequency, we determined the transient motion and the stable limit cycles of the network formed by the three oscillators, showing the behavior of the knee angles and the hip angle. A comparison of the plotted graphs revealed that the system provided excellent results when compared to experimental analysis. Based on the results of the study, we come to the conclusion that the use of mutually coupled Rayleigh oscillators can represent an excellent method of signal generation, allowing their application for feedback control of a walking machine.Acknowledgements The authors would like to express their gratitude to CNPq and CAPES for the financial support provided during the course of this research.     

Reciprocal mouse and human limb phenotypes caused by gain- and loss-of-function mutations affecting Lmbr1

An intensive linkage map of the yellow fever mosquito, Aedes aegypti, was constructed using single-strand conformation polymorphism (SSCP) analysis of cDNA markers to identify single nucleotide polymorphisms (SNPs). A total of 94 A. aegypti cDNAs were downloaded from GenBank and primers were designed to amplify fragments <500 bp in size. These primer pairs amplified 94 loci, 57 (61%) of which segregated in a single F(1) intercross family among 83 F(2) progeny. This allowed us to produce a dense linkage map of one marker every 2 cM distributed over a total length of 134 cM. Many A. aegypti cDNAs were highly similar to genes in the Drosophila melanogaster genome project. Comparative linkage analysis revealed areas of synteny between the two species. SNP polymorphisms are abundant in A. aegypti genes and should prove useful in both population genetics and mapping studies.     

Immobilization of pneumococcal polysaccharide vaccine on silicon oxide wafer for an acoustical biosensor.

One the most important aspects of a biosensor is related to immobilization and maintenance of specific reference compounds on sensing surfaces. A method for the immobilization of polysaccharides to a silicon oxide surface intended for Surface Acoustical Waves (SAW) sensors is described. Silicon oxide is a hydrophobic inorganic support used for the fabrication of many electronic devices. The pneumococcal polysaccharide (PPS) vaccine is immobilized via Protein A after pre-treatment of the surface with hydrochloric acid. The effects of non-specific binding are discussed. The results indicate that the immobilization of PPS via Protein A increases the sensitivity of detecting Streptococcus pneumoniae antibodies in human sera and offers greater reproducibility of response compared with ELISA methods. The principles of this technique are simple and are applicable to the immobilization of many capsular polysaccharides.