Synaptosomes isolated from Goto-Kakizaki diabetic rat brain exhibit increased resistance to oxidative stress: role of vitamin E

Increased oxidative stress is believed to be an important factor in the development of diabetic complications. In this study, the effect of diabetes on the susceptibility of synaptosomes to oxidative stress, induced by the oxidizing system ascorbate/Fe2+, on the activity of antioxidant enzymes and on the levels of glutathione and vitamin E was investigated. Synaptosomes were isolated from brain of 29-weeks-old Goto-Kakizaki (GK) rats, a model of non-insulin dependent diabetes mellitus and from normal Wistar rats. Synaptosomes isolated from GK rats displayed a lower susceptibility to lipid peroxidation, as assessed by quantifying thiobarbituric acid reactive substances (TBARS), than normal rats (5.33 +/- 0.79 and 7.58 +/- 0.7 nmol TBARS/mg protein, respectively). In the absence of oxidants, no significant differences were found between the levels of peroxidation in synaptosomes of diabetic or control rats. Superoxide dismutase (SOD), glutathione peroxidase and glutathione reductase activities were unaltered in the brain of diabetic rats. There were no statistically significant differences in fatty acid composition of total lipids and reduced glutathione levels in synaptosomes of diabetic and control rats. The decreased susceptibility to membrane lipid peroxidation of diabetic rats synaptosomes correlated with a 1.3-fold increase in synaptosomal vitamin E levels. Vitamin E levels in plasma were also higher in diabetic rats (21.32 micromol/l) as compared to normal rats (15.13 micromol/l). We conclude that the increased resistance to lipid peroxidation in GK rat brain synaptosomes may be due to the increased vitamin E content, suggesting that diabetic animals might develop enhanced defense systems against brain oxidative stress.     

Prediction of total fecal output in sheep fed silage using the Captec chrome controlled-release capsule

Six Finnish wethers (average weight, 52.3 kg) were used to determine the effectiveness of a controlled-release Cr₂O₃ bolus and the internal marker acid insoluble ash (AIA) for predicting fecal output. Wethers were fed grass silage for ad libitum intake. Each wether was dosed orally with one continuous-release Cr₂O₃ bolus (CRC) on the first day of the experiment. Chronology of the trial was as follows: Day 0 to 14, marker adaptation period; Day 15 to 21, total fecal collection; Day 22 to 23, fecal grab sampling every 4 h; Day 25 to 35, once-daily fecal grab sampling. Accuracy of marker-estimated fecal output derived from each method was compared within a marker with total fecal collection values using a paired t-test. Concentrations of AIA and Cr varied (P < 0.10) between sampling times. Accuracy of fecal output estimates was better with the controlled-release Cr₂O₃ bolus (r = 0.97; P = 0.03) than with AIA (r = −0.08; P = 0.89). Grab samples taken once produced reliable (r = 0.96; P = 0.02) estimates of fecal output of silage-fed wethers using the controlled-release Cr₂O₃ bolus. The controlled-release Cr₂O₃ bolus is a better marker than acid-insoluble ash for predicting fecal output of silage-fed wethers.     

Detecting network communities: an application to phylogenetic analysis

This paper proposes a new method to identify communities in generally weighted complex networks and apply it to phylogenetic analysis. In this case, weights correspond to the similarity indexes among protein sequences, which can be used for network construction so that the network structure can be analyzed to recover phylogenetically useful information from its properties. The analyses discussed here are mainly based on the modular character of protein similarity networks, explored through the Newman-Girvan algorithm, with the help of the neighborhood matrix . The most relevant networks are found when the network topology changes abruptly revealing distinct modules related to the sets of organisms to which the proteins belong. Sound biological information can be retrieved by the computational routines used in the network approach, without using biological assumptions other than those incorporated by BLAST. Usually, all the main bacterial phyla and, in some cases, also some bacterial classes corresponded totally (100%) or to a great extent (>70%) to the modules. We checked for internal consistency in the obtained results, and we scored close to 84% of matches for community pertinence when comparisons between the results were performed. To illustrate how to use the network-based method, we employed data for enzymes involved in the chitin metabolic pathway that are present in more than 100 organisms from an original data set containing 1,695 organisms, downloaded from GenBank on May 19, 2007. A preliminary comparison between the outcomes of the network-based method and the results of methods based on Bayesian, distance, likelihood, and parsimony criteria suggests that the former is as reliable as these commonly used methods. We conclude that the network-based method can be used as a powerful tool for retrieving modularity information from weighted networks, which is useful for phylogenetic analysis.     

Quality of Seeds Produced by Psychotria tenuinervis (Rubiaceae): Distance from Anthropogenic and Natural Edges of Atlantic Forest Fragment

The aim of this study was to investigate whether there were differences in the genetic variability and rate and velocity of the seed germination produced by Psychotria tenuinervis located at anthropogenic edges, natural edges, and in the forest interior. The populations of P. tenuinervis showed no differences in genetic variability or structure among the three habitats. There was, however, an indication of inbreeding, which was significantly higher in natural edges than in anthropogenic edges and the forest interior. Within-habitat variation was considerable, but there were no differences in seed mass or rate and velocity of germination among the three habitats. These results suggest that seed characteristics were not influenced by the genetic pattern of P. tenuinervis and that other characteristics of the forest fragment, such as gaps, edge age, and type of matrix exert more influence on seed mass and germination than the distance from the edges.     

Reduced plasma angiotensin II levels are reversed by hydroxyurea treatment in mice with sickle cell disease

Aims

Sickle cell disease (SCD) pathogenesis leads to recurrent vaso-occlusive and hemolytic processes, causing numerous clinical complications including renal damage. As vasoconstrictive mechanisms may be enhanced in SCD, due to endothelial dysfunction and vasoactive protein production, we aimed to determine whether the expression of proteins of the renin–angiotensin system (RAS) may be altered in an animal model of SCD.

Main methods

Plasma angiotensin II (Ang II) was measured in C57BL/6 (WT) mice and mice with SCD by ELISA, while quantitative PCR was used to compare the expressions of the genes encoding the angiotensin-II-receptors 1 and 2 (AT1R and AT2R) and the angiotensin-converting enzymes (ACE1 and ACE2) in the kidneys, hearts, livers and brains of mice. The effects of hydroxyurea (HU; 50–75 mg/kg/day, 4 weeks) treatment on these parameters were also determined.

Key findings

Plasma Ang II was significantly diminished in SCD mice, compared with WT mice, in association with decreased AT1R and ACE1 expressions in SCD mice kidneys. Treatment of SCD mice with HU reduced leukocyte and platelet counts and increased plasma Ang II to levels similar to those of WT mice. HU also increased AT1R and ACE2 gene expression in the kidney and heart.

Significance

Results indicate an imbalanced RAS in an SCD mouse model; HU therapy may be able to restore some RAS parameters in these mice. Further investigations regarding Ang II production and the RAS in human SCD may be warranted, as such changes may reflect or contribute to renal damage and alterations in blood pressure.     

Purification, and biochemical and biophysical characterization of cellobiohydrolase I from Trichoderma harzianum IOC 3844

Because of its elevated cellulolytic activity, the filamentous fungus Trichoderma harzianum has a considerable potential in biomass hydrolysis applications. Trichoderma harzianum cellobiohydrolase I (ThCBHI), an exoglucanase, is an important enzyme in the process of cellulose degradation. Here, we report an easy single-step ion-exchange chromatographic method for purification of ThCBHI and its initial biophysical and biochemical characterization. The ThCBHI produced by induction with microcrystalline cellulose under submerged fermentation was purified on DEAE-Sephadex A-50 media and its identity was confirmed by mass spectrometry. The ThCBHI biochemical characterization showed that the protein has a molecular mass of 66 kDa and pI of 5.23. As confirmed by smallangle X-ray scattering (SAXS), both full-length ThCBHI and its catalytic core domain (CCD) obtained by digestion with papain are monomeric in solution. Secondary structure analysis of ThCBHI by circular dichroism revealed alpha- helices and beta-strands contents in the 28% and 38% range, respectively. The intrinsic fluorescence emission maximum of 337 nm was accounted for as different degrees of exposure of ThCBHI tryptophan residues to water. Moreover, ThCBHI displayed maximum activity at pH 5.0 and temperature of 50 degrees C with specific activities against Avicel and p-nitrophenyl-β-D-cellobioside of 1.25 U/mg and 1.53 U/mg, respectively.     

A comparative analysis of the citrate permease P mRNA stability in Lactococcus lactis biovar diacetylactis and Escherichia coli

The role of ribonucleases in the control of gene expression remains unknown in lactic acid bacteria. In the present work, we analysed the expression of the citP gene, which encodes the lactococcal citrate permease P, through the stability of the citQRP messenger in both Lactococcus lactis biovar diacetylactis (L. diacetylactis) and Escherichia coli. The chemical half-life for citQRP mRNA observed in L. diacetylactis wild-type strain was abnormally long for bacteria. It was even longer than that detected in E. coli RNase E or RNase III mutant strains. A model of processing and fate of RNA species containing citP gene is presented.     

Isomucor (Mucoromycotina): a new genus from a Cerrado reserve in state of Sao Paulo, Brazil

During a survey of mucoralean fungi from a Cerrado reserve (Brazilian savanna) some isolates of a Mucor-like fungus were isolated from soil plates. Characterization based on morphological, physiological and molecular data from translation elongation factor (EF-1α), 28S (D1/D2) and ITS1-5.8S-ITS2 rDNA sequences was made. The isolates produce lateral branches bearing multispored sporangiola in addition to the multispored sporangia and a uniformly septate mycelium as the main differentiating characteristics. To our surprise this fungus possesses two EF-1α genes 1.4 and 1.5 kb long. Evidence from the analyzed datasets supports the delimitation of a new genus and the inclusion of Mucor fuscus based on 28S and ITS rDNA data.     

Factors potentially affecting fertility of lactating dairy cow recipients

Objectives of this study were to evaluate factors that could affect pregnancy rate after embryo transfer (ET) in lactating dairy cow recipients. The trial was conducted at a dairy farm located in Descalvado, SP, Brazil from October 2003 to September 2004. From 1037 cows with CL that were treated with an injection of PGF2alpha, 43.3% were detected in heat; 263 were previously assigned at day of PGF2alpha injection for AI and 186 for ET. Ovulation rate was 85.7% (385/449). Pregnancy rate for cows with CL for AI and embryo transfer recipients were 36.5% (84/230) and 58.7% (91/155) at day 25 and 33.0% (76/230) and 45.8% (71/155) at day 46, respectively. Embryonic loss were 9.5% (8/84) for the AI group and 21.9% (20/91) for the ET group. Average milk production was 31.4 L/day/cow. Average daily milk production from 7 days before PGF2alpha injection to 7 days after ET tended (P < 0.10) to influence pregnancy rate on days 25 and 46. Average daily milk production from the day of embryo transfer to 7 days after influenced embryonic loss (P < 0.05). Cows with higher milk production had lower probability of pregnancy and higher probability of embryonic loss. Cows with higher days in milk had higher probability of pregnancy. Cows with higher rectal body temperature had lower probability of pregnancy and higher probability of embryonic loss. The influence of high milk yield and body temperature on fertility in lactating dairy cow recipients suggests that these effects can occur also after embryo reaches the blastocyst stage.     

Cryopreservation of immature equine oocytes, comparing a solid surface vitrification process with open pulled straws and the use of a synthetic ice blocker

The objective was to evaluate the effect of three cryopreservation methods on the in vitro maturation (IVM) and membrane integrity (MIn) of immature equine oocytes. An open pulled straw (OPS) method, a novel solid surface vitrification (SSV) process, and the addition of a synthetic ice blocker were evaluated. Compared with the control group (N = 269), the OPS (N = 159) and the SSV (N = 202) cryopreservation methods decreased both IVM (50.9 vs. 13.3 and 9.4%, respectively; P < 0.001) and MIn (76.6 vs. 31.1 and 33.7%; P < 0.001) of immature equine oocytes. However, inclusion of 0.1% ice blocker in the OPS vitrification process increased the rates of both IVM (30.5%; P < 0.01) and MIn (45.8%; P < 0.05) of the oocytes (N = 59). Including 0.1% ice blocker in the SSV process improved the IVM rate (20.9%; P < 0.05), whereas MIn remained compromised in this group (N = 67). However, increasing the concentration of the ice blocker (to 1.0%) in the cryopreservation methods did not significantly improve rates of IVM. In conclusion, the addition of a synthetic ice blocker (0.1%) to both cryopreservation processes significantly increased rates of both IVM and MIn of immature equine oocytes cryopreserved by OPS.