Effect of intragenic rearrangement and changes in the 3' consensus sequence on NSP1 expression and rotavirus replication

The nonpolyadenylated mRNAs of rotavirus are templates for the synthesis of protein and the segmented double-stranded RNA (dsRNA) genome. During serial passage of simian SA11 rotaviruses in cell culture, two variants emerged with gene 5 dsRNAs containing large (1.1 and 0.5 kb) sequence duplications within the open reading frame (ORF) for NSP1. Due to the sequence rearrangements, both variants encoded only C-truncated forms of NSP1. Comparison of these and other variants encoding defective NSP1 with their corresponding wild-type viruses indicated that the inability to encode authentic NSP1 results in a small-plaque phenotype. Thus, although nonessential, NSP1 probably plays an active role in rotavirus replication in cell culture. In determining the sequences of the gene 5 dsRNAs of the SA11 variants and wild-type viruses, it was unexpectedly found that their 3' termini ended with 5'-UGAACC-3' instead of the 3' consensus sequence 5'-UGACC-3', which is present on the mRNAs of nearly all other group A rotaviruses. Cell-free assays indicated that the A insertion into the 3' consensus sequence interfered with its ability to promote dsRNA synthesis and to function as a translation enhancer. The results provide evidence that the 3' consensus sequence of the gene 5 dsRNAs of SA11 rotaviruses has undergone a mutation causing it to operate suboptimally in RNA replication and in the expression of NSP1 during the virus life cycle. Indeed, just as rotavirus variants which encode defective NSP1 appear to have a selective advantage over those encoding wild-type NSP1 in cell culture, it may be that the atypical 3' end of SA11 gene 5 has been selected for because it promotes the expression of lower levels of NSP1 than the 3' consensus sequence.     

Correlation between catalysis and tertiary structure arrangement in an archaeal halophilic subtilase

Nep (Natrialba magadii extracellular protease) is a halolysin-like peptidase secreted by the haloalkaliphilic archaeon N. magadii that exhibits optimal activity and stability in salt-saturated solutions. In this work, the effect of salt on the function and structure of Nep was investigated. In absence of salt, Nep became unfolded and aggregated, leading to the loss of activity. The enzyme did not recover its structural and functional properties even after restoring the ideal conditions for catalysis. At salt concentrations higher than 1 M (NaCl), Nep behaved as monomers in solution and its enzymatic activity displayed a nonlinear concave-up dependence with salt concentration resulting in a 20-fold activation at 4 M NaCl. Although transition from a high to a low-saline environment (3–1 M NaCl) did not affect its secondary structure contents, it diminished the enzyme stability and provoked large structural rearrangements, changing from an elongated shape at 3 M NaCl to a compact conformational state at 1 M NaCl. The thermodynamic analysis of peptide hydrolysis by Nep suggests a significant enzyme reorganization depending on the environmental salinity, which supports in solution SAXS and DLS studies. Moreover, solvent kinetic isotopic effect (SKIE) data indicates the general acid-base mechanism as the rate-limiting step for Nep catalysis, like classical serine-peptidases. All these data correlate the Nep conformational states with the enzymatic behavior providing a further understanding on the stability and structural determinants for the functioning of halolysins under different salinities.     

Neuropathic Pain Modifies Antioxidant Activity in Rat Spinal Cord

Oxidative stress is an important pathophysiological mechanism of many neurological diseases. Reactive oxygen and nitrogen species have been cited as molecules involved in the nociceptive process. In this study, rats were submitted to sciatic nerve transection (SNT) for induction of neuropathic pain, and enzyme activities of SOD and catalase as well as lipid peroxidation (LPO) were measured in the lumbosacral spinal cord. The results show that LPO was not changed after SNT. SOD activity was reduced 7 days after SNT, while the change in catalase activity occurred on the third and seventh days in both sham and SNT animals. Hyperalgesia in SNT group was detected at the same points in time. These results suggest that SNT was not a strong enough stimulus to deplete all antioxidant content in the spinal cord, since increase in LPO was not detected. However, the role of oxidative stress in nociception can not be excluded.     

Feasibility of ethanol production from coffee husks

The objective of this work was to evaluate the feasibility of ethanol production by fermentation of coffee husks by Saccharomyces cerevisiae. Batch fermentation studies were performed employing whole and ground coffee husks, and aqueous extract from ground coffee husks. It was observed that fermentation yield decreased with an increase in yeast concentration. The best results were obtained for the following conditions: whole coffee husks, 3 g yeast/l substrate, temperature of 30°C. Under these conditions ethanol production was 8.49 ± 0.29 g/100 g dry basis (13.6 ± 0.5 g ethanol/l), a satisfactory value in comparison to literature data for other residues such as corn stalks, barley straw and hydrolyzed wheat stillage (5–11 g ethanol/l). Such results indicate that coffee husks present excellent potential for residue-based ethanol production.     

Antioxidant properties and total phenolic contents of some tropical seaweeds of the Brazilian coast

Many types of macroalgae contain a wide range of bioactive compounds that have antioxidant potential. However, in contrast to terrestrial plants, only a few studies have reported the antioxidant activity of seaweeds. Therefore, extracts from 26 marine macroalgae species from the south and southeast coasts of Brazil were evaluated for their antioxidant activity, using the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) method and β-carotene/linoleic acid assay, and their total phenolic contents, through Folin–Ciocalteu method. Padina gymnospora, Sargassum vulgare, and Osmundaria obtusiloba presented the highest values of total phenolic content. Using β-carotene bleaching assay, Colpomenia sinuosa, Dictyota sp., Dichotomaria marginata, Ganonema farinosum, and Spyridia clavata presented up to 65 % of antioxidant activity. Some of the extracts showed more than 60 % of inhibition of DPPH in the lowest concentration (0.01 mg/mL), including Amansia sp., Bostrychia tenella, Cryptonemia seminervis, Hypnea musciformis, Plocamium brasiliense (1), and S. clavata. Both Amansia sp., and C. seminervis presented the most relevant antioxidant potential, with percentage of inhibition greater than 70 % in the three tested concentrations. These two species were then analyzed by nuclear magnetic resonance spectroscopy (NMR) and were selected for guided fractionation bioassay. They both presented lipid compounds, fatty acids, esters of fatty acids, triglycerides, and sterols as major components. The fractionation of extracts revealed that the organic fractions were responsible for the antioxidant activity. The results obtained through this work indicate that the analyzed seaweeds are a promising source of compounds with high antioxidant potential.     

Effects of UV-B radiation on Gelidium floridanum (Rhodophyta, Gelidiales): germination of tetraspores and early sporeling development

The increased incidence of UV-B radiation, particularly in southern South America, has sparked more interest in its effects on marine organisms. Here we describe the effects of UV-B on the early life stages of Gelidium floridanum, an agar-producing species abundant on rocky coasts in southern Brazil. Treated samples were submitted to 0.12 W?m^?2 of artificial UV-B radiation for 2 h per day over a 15-day period. UV-B exposure induced impairment of tetraspore germination and germling development. We observed a delay in germination, a reduced growth rate of tetrasporelings, and morphological changes, such as a different length-to-width ratio, twisted thallus, loss of pigmentation, and differentiation of more than one apical cell, all leading to a different growth pattern in sporelings that survived treatment. Results indicated a great susceptibility of early-developing Gelidium to UV-B, even at low irradiance and short exposure time.     

BAC- and oligo-FISH mapping reveals chromosome evolution among Vigna angularis,V. unguiculata,and Phaseolus vulgaris

Chromosoma - Cytogenomic resources have accelerated synteny and chromosome evolution studies in plant species, including legumes. Here, we established the first cytogenetic map of V. angularis (Va,...