Temporal Progress of Yellow Sigatoka and Aerobiology of Mycosphaerella musicola Spores

An understanding of the progression of a disease is important in the adoption of control strategies as well as the evaluation of their efficacies. Temporal analysis is especially useful because it integrates the evolution of the interaction between the components of the pathosystem, as expressed by the accumulated data on the incidence and severity of disease and depicted by the disease progression curve. Within a given patho‐system, the dispersed airborne spores are important components in the progress of plant disease epidemics. Our aims were to evaluate the temporal dynamics of yellow Sigatoka in a banana plantation located in Coronel Pacheco, MG, Brazil, and to assess the aerobiology of Mycosphaerella musicola spores throughout the year. During the rainy season, we observed intense disease progression concomitant with high rates of leaf emission, which caused rapid reversal of the severity peaks after the maximum rates were reached. The yellow Sigatoka progress curve showed two peaks of extreme severity. The first, which occurred during the rainy season, was predominantly caused by a high concentration of conidia. The second, which occurred during the dry season, was predominantly caused by a high concentration of ascospores in the air. The ascospore concentrations were correlated with the severity of the disease 29 days later, indicating the average latency period of the disease in that region. The patterns of the severity curves for both peaks fit the monomolecular model, and the progression rates were higher during the rainy season than the dry season. The spore concentrations were the same at the two evaluated heights. In all evaluations, it was observed a higher concentration of ascospores than of conidia, with the greatest ascospore concentrations occurring during the early hours of the day and the greatest conidia concentrations occurring later, after the dew has dropped from the leaves.     

Proteomic characterization of the hyaluronidase (E.C. 3.2.1.35) from the venom of the social wasp Polybia paulista

Polybia paulista wasp venom possesses three major allergens: phospholipase A1, hyaluronidase and antigen-5. To the best of our knowledge, no hyaluronidase from the venom of Neotropical social wasps was structurally characterized up to this moment, mainly due to its reduced amount in the venom of the tropical wasp species (about 0.5% of crude venom). Four different glycoproteic forms of this enzyme were detected in the venom of the wasp Polybia paulista. In the present investigation, an innovative experimental approach was developed combining 2-D SDS-PAGE with in-gel protein digestion by different proteolytic enzymes, followed by mass spectrometry analysis under collision-induced dissociation CID) conditions for the complete assignment of the protein sequencing. Thus, the most abundant form of this enzyme in P. paulista venom, the hyaluronidase-III, was sequenced, revealing that the first 47 amino acid residues from the N-terminal region, common to other Hymenoptera venom hyaluronidases, are missing. The molecular modeling revealed that hyaluronidase-III has a single polypeptide chain, folded into a tertiary structure, presenting a central (β/α)5 core with alternation of β-strands and α-helices; the tertiary structure stabilized by a single disulfide bridge between the residues Cys189 and Cys201. The structural pattern reported for P. paulista venom hyaluronidase-III is compatible with the classification of the enzyme as member of the family 56 of glycosidase hydrolases. Moreover, its structural characterization will encourage the use of this protein as a model for future development of "component-resolved diagnosis".     

Determination of LC50 of permethrin acaricide in semi-engorged females of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

Currently, the most efficient and widely used method of tick control still is the treatment with acaricides, especially permethrin (active ingredient of the Advantage^® Max3, Bayer), a pyrethroid with neurotoxic action. Due to the wide use of this acaricide in the control of the tick Rhipicephalus sanguineus, this study carried out laboratorial procedures to determine the LC₅₀ (lethal concentration fifty) of permethrin in semi-engorged females of R. sanguineus. Based on the result of 14 dilutions of permethrin in distilled water and later Probit analysis, the LC₅₀ of permethrin for R. sanguineus was 2062 ppm (1549-2675 ppm). This work can be used as a protocol with other chemicals, to determinate the LC₅₀, basic procedure for studies of control, resistance and behavior of ticks treated with acaricides, especially the brown dog tick R. sanguineus. Also, the knowledge of the LC₅₀ provides information on the potency of chemicals, the sensitivity of Arthropods to them and even estimates on pest control.     

Mutagenic and Genotoxic Effects of <Emphasis Type="Italic">cis</Emphasis>-(Dichloro)tetraammineruthenium(III) Chloride on Human Peripheral Blood Lymphocytes

Chemotherapeutic agents play an important role in cancer treatment mostly due their systemic action on human organism allowing access to liquid tumors and even metastases. Among these drugs, ruthenium compounds have been showing promising results to treat tumors and represent an important development of new antitumor therapy. This study presents the evaluation of cis-(dichloro)tetraammineruthenium(III) chloride, cis-[RuCl₂(NH₃)₄]Cl, genotoxic effects using human peripheral blood lymphocytes cultured in vitro. Mitotic index (MI), chromosome aberrations (CA), and DNA damage using the comet assay were analyzed. MI in human peripheral blood lymphocyte cultures treated with 1, 10, 100, and 1,000 μg mL⁻¹ cis-[RuCl₂(NH₃)₄]Cl were 5.9%, 4.6%, 3.9%, and 0%, respectively. Doxorubicin chloridate was used as the positive control. CA derived from 1, 10, and 100 μg mL⁻¹ concentrations were defined as spontaneous when compared with the negative control, and at the concentration of 1,000 μg mL⁻¹, the cell cycle was inhibited (IM = 0%). Results obtained for the comet assay using cis-[RuCl₂(NH₃)₄]Cl suggest that this compound has no genotoxic activity against cultured human peripheral blood lymphocytes.     

Electromyographic evaluation of upper limb muscles involved in armwrestling sport simulation during dynamic and static conditions

ObjectiveTo evaluate the electromyographic activity of the Pectoralis Major (PM), Biceps Brachii (BB), Pronator Teres (PT) and Flexor Carpi Ulnaris (FCU) muscles involved in simulated armwrestling.MethodsTen trained volunteers were selected to perform the armwrestling movement, during dynamic tests with 40% and 80% of maximum voluntary load (MVL) and static tests in the initial, intermediary and final positions. Electromyographic and force data were normalized for analyses.ResultsIn dynamic tests with 40% MVL, electric activity of the PT muscle was greater than FCU (p < 0.01) and BB (p < 0.05) muscles, and with 80% MVL, PM and PT muscles were the most active. In static tests, electric activity increased from the initial to final positions for the PM muscle (p < 0.05), while it decreased for the BB and PT muscles (p < 0.001 and p < 0.05, respectively). No significant changes were observed for force and no correlation was found with the simultaneous electric activity.ConclusionsIt can be concluded that the PM and FCU muscles participate as agonists in the simulated armwrestling whereas the BB and PT muscles seem to perform secondary functions. Electric activity showed to be dependent on the load and on the position of the upper limb, but not on the force produced during the movement.     

Monoclonal antibody purification using cationic polyelectrolytes: an alternative to column chromatography

The potential of cationic polyelectrolytes to precipitate host cell and process related impurities was investigated, to replace one or more chromatography steps in monoclonal antibody purification. The impact of antibody isoelectric point, solution properties (pH and ionic strength), and polyelectrolyte properties (structure, molecular weight and pK(a)) on the degree of precipitation was studied. At neutral pH, increasing solution ionic strength impeded the ionic interaction between the polyelectrolyte and impurities, reducing impurity precipitation. Increasing polyelectrolyte molecular weight and pK(a) enabled precipitation of impurities at higher ionic strength. PoIy(arginine) was selected as the preferred polyelectrolyte in unconditioned cell culture fluid. PoIy(arginine) precipitation achieved consistent host cell protein clearance and antibody recovery for multiple antibodies across a wider range of polyelectrolyte concentrations. Poly(arginine) precipitation was evaluated as a flocculant and as a functional replacement for anion exchange chromatography in an antibody purification process. Upstream treatment of cell culture fluid with poly(arginine) resulted in flocculation of solids (cells and cell debris), and antibody recovery and impurity clearance (host cell proteins, DNA and insulin) comparable to the downstream anion exchange chromatography step.     

Association between MUC1 gene polymorphism and expected progeny differences in Nelore cattle (Bos primigenius indicus)

MUC1 is a heavily glycosylated mammalian transmembrane protein expressed by mucosal secretory tissues for both protection against microbial infection and lubrication. An important characteristic of MUC1 is its variable number of tandem repeats (VNTR) containing several sites for O-glycosylation. VNTR length has been associated with many human diseases and with certain economically important traits in domestic ruminants. The aim of the present study was to correlate the length of MUC1 gene VNTR with expected progeny differences (EPDs) obtained for growth, fertility and carcass traits. Five alleles were identified, with alleles containing short VNTRs being more frequent than those with long, thereby demonstrating that Brazilian Nelore cattle are characterized by high frequencies in short MUC1 VNTRs. Statistical analyses revealed there to be no significant association between VNTR length and EPDs for weight at 120 days (W(120) ), scrotal circumference at 365 (SC (365) ) and 450 (SC (450) ) days, age at first calving (AFC), and rib eye area (REA).     

Herpetomonas samuelpessoai: dimethylsulfoxide-induced differentiation is influenced by proteinase expression

In this study, we analyzed the influence of proteinase expression on the cellular differentiation of Herpetomonas samuelpessoai. Along cellular differentiation, which was induced by dimethylsulfoxide (DMSO), the trypanosomatids secreted several molecules with variable proteolytic activity. All of them were inhibited by 10 m M 1,10-phenanthroline, suggesting that they are zinc-metalloproteinases. Analysis of parasite extracts revealed the occurrence of a 63-kDa metalloproteinase and a 45-kDa cysteine proteinase. After extraction with Triton X-114 followed by water-detergent partition, the 63-kDa component was present in both aqueous and detergent phases, which indicated that this enzyme may be distributed over different cellular compartments including membrane domains. The 45-kDa component, however, presented hydrophilic properties and was predominantly expressed by DMSO non-treated parasites, suggesting that proteinases may be involved in the process of cellular differentiation in H. samuelpessoai. This was confirmed by the fact that a cysteine proteinase inhibitor abrogated parasite differentiation. The role of proteinases and their relevance in the differentiation of H. samuelpessoai are discussed.     

Palmitoylation,membrane-proximal basic residues,and transmembrane glycine residues in the reovirus p10 protein are essential for syncytium formation

Avian reovirus and Nelson Bay reovirus are two unusual nonenveloped viruses that induce extensive cell-cell fusion via expression of a small nonstructural protein, termed p10. We investigated the importance of the transmembrane domain, a conserved membrane-proximal dicysteine motif, and an endodomain basic region in the membrane fusion activity of p10. We now show that the p10 dicysteine motif is palmitoylated and that loss of palmitoylation correlates with a loss of fusion activity. Mutational and functional analyses also revealed that a triglycine motif within the transmembrane domain and the membrane-proximal basic region were essential for p10-mediated membrane fusion. Mutations in any of these three motifs did not influence events upstream of syncytium formation, such as p10 membrane association, protein topology, or surface expression, suggesting that these motifs are more intimately associated with the membrane fusion reaction. These results suggest that the rudimentary p10 fusion protein has evolved a mechanism of inducing membrane merger that is highly dependent on the specific interaction of several different motifs with donor membranes. In addition, cross-linking, coimmunoprecipitation, and complementation assays provided no evidence for p10 homo- or heteromultimer formation, suggesting that p10 may be the first example of a membrane fusion protein that does not form stable, higher-order multimers.     

Overexpression of SR-BI by adenoviral vector reverses the fibrateinduced hypercholesterolemia of apolipoprotein E-deficient mice

The hypercholesterolemia characteristic of apolipoprotein (apoE)-deficient mice fed on a regular chow diet is caused by the abnormal accumulation of apoB-48-carrying remnants of chylomicrons and very low density lipoproteins in the plasma. Treatment of apoE-deficient mice with ciprofibrate or other peroxisome proliferator-activated receptor alpha agonists severely aggravates their hypercholesterolemia by interfering with one or more mechanisms of remnant removal from the circulation that do not require mediation by apoE (Fu, T., Kashireddy, P., and Borensztajn, J. (2003) Biochem. J. 373, 941-947). In the present investigation we report that ciprofibrate treatment causes the down-regulation of hepatic scavenger receptor class B, type I (SR-BI) protein expression in the livers of apoE-deficient mice. On cessation of the treatment SR-BI expression returns to its pretreatment levels, coinciding with a reversal of the hypercholesterolemia to base-line concentrations. Restoration of SR-BI expression in ciprofibrate-treated apoE-deficient mice by recombinant adenoviral gene transfer abolishes the ciprofibrate-induced over accumulation of apoB-48-carrying remnants in the plasma. We also report that remnants isolated from the plasma of ciprofibrate-treated apoE-deficient mice bind to murine SR-BI expressed in stably transfected cultured cells. These observations suggest that, in addition to its well established role as high density lipoprotein receptor, SR-BI can also function as a remnant receptor responsible for the clearance of remnants from the circulation of apoE-deficient mice.