Evaluating the microbicidal, antiparasitic and antitumor effects of CR-LAAO from Calloselasma rhodostoma venom

CR-LAAO is an l-amino acid oxidase from Calloselasma rhodostoma snake venom that has been broadly studied regarding its structural and biochemical characteristics, however, few studies have investigated its pharmacological effects. The present study aimed at the evaluation of the biotechnological potential of CR-LAAO by determining its bactericidal, antifungal, leishmanicidal and trypanocidal activity, as well as its cytotoxicity on human tumor and non-tumor cell lines. After 24h of preincubation, CR-LAAO showed bactericidal effects against both Staphylococcus aureus (MIC 0.78μg/mL) and Escherichia coli (MIC 31.25μg/mL) strains, inducing dismantle of bacterial cell walls. After 6h of preincubation with Candida albicans, CR-LAAO was able to inhibit 80% of the yeast growth, and it also showed cytotoxic activity on Leishmania species and Trypanosoma cruzi. Additionally, CR-LAAO showed high cytotoxicity on HepG2 and HL-60 tumor cells (IC50 10.78 and 1.7μg/mL), with lower effects on human mononuclear cells (PBMC). The cytotoxic effects of CR-LAAO were significantly inhibited in the presence of catalase, which suggests the involvement of hydrogen peroxide in its mechanisms of toxicity. Therefore, CR-LAAO showed promising pharmacological effects, and these results provide important information for the development of therapeutic strategies with directed action, such as more effective antimicrobial agents.

Proteomic analysis of the rare Uracoan rattlesnake Crotalus vegrandis venom: evidence of a broad arsenal of toxins

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

Bothropoides pauloensis venom effects on isolated perfused kidney and cultured renal tubular epithelial cells

Coordenadação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bromeliads as biodiversity amplifiers and habitat segregation of spider communities in a Neotropical rainforest

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

Thrombocytopenia and platelet hypoaggregation induced by Bothrops asper snake venom Toxins involved and their contribution to metalloproteinase-induced pulmonary hemorrhage

Thrombocytopenia and platelet dysfunction occur in patients bitten by Bothrops sp snakes in Latin America. An experimental model was developed in mice to study the effects of B. asper venom in platelet numbers and function. Intravenous administration of this venom induces rapid and prominent thrombocytopenia and ex vivo platelet hypoaggregation. The drop in platelet numbers was primarily due to aspercetin, a protein of the C-type lectin family which induces von Willebrand factor-mediated platelet aggregation/agglutination. In addition, the effect of class P-III hemorrhagic metalloproteinases on the microvessel wall also contributes to thrombocytopenia since jararhagin, a P-III metalloproteinase, reduced platelet counts. Hypoaggregation was associated with the action of procoagulant and defibrin(ogen)ating proteinases jararacussin-1 (a thrombin-like serine proteinase) and basparin A (a prothrombin activating metalloproteinase). At the doses which induced hypoaggregation, these enzymes caused defibrin(ogen)ation, increments in fibrin(ogen) degradation products and D-dimer and prolongation of the bleeding time. Incubation of B. asper venom with batimastat and α 2-macroglobulin abrogated the hypoaggregating activity, confirming the role of venom proteinases in this effect. Neither aspercetin nor the defibrin(ogen)ating and hypoaggregating components induced hemorrhage upon intravenous injection. However, aspercetin, but not the thrombin-like or the prothrombin-activating proteinases, potentiated the hemorrhagic activity of two hemorrhagic metalloproteinases in the lungs. © 2005 Schattauer GmbH, Stuttgart.

Study of visceral antinociceptive potential of bee Apis mellifera venom

Pain is one of the most common reasons for patients to seek medical care. Bee Apis mellifera venom (AMV) has traditionally been used to treat inflammatory diseases and the alleviation of pain. Herein, we aimed to investigate the visceral antinociceptive potential of A. mellifera bee venom and its possible mechanism of action. Acetic acid-induced writhing assay was used in mice to determine the degree of visceral antinociception. Visceral antinociceptive activity was expressed as the reduction in the number of abdominal constrictions. Mice received an intraperitoneal injection of acetic acid after administration of AMV (0.08 or 0.8 mg/kg; intraperitoneally (i.p.)). In mechanistic studies, separate experiments were realized to examine the role of α2-receptors, nitric oxide, calcium channels, K+ATP channel activation, TRPV1 and opioid receptors on the visceral antinociceptive effect of AMV (0.8 mg/kg), using appropriate antagonists, yohimbine (2 mg/kg), L-NG-Nitroarginine methyl ester (L-NAME, 10 mg/kg), verapamil (5 mg/kg), glibenclamide (5 mg/kg), ruthenium red (3 mg/kg) or naloxone (2 mg/kg). AMV presented visceral antinociceptive activity in both doses tested (0.08 and 0.8 mg/Kg). Visceral antinociceptive effect of AMV was resistant to all the antagonists used. Mice showed no significant alterations in locomotion frequency, indicating that the observed antinociception is not a consequence of motor abnormality. Although AMV efficient diminished the acetic acid-evoked pain-related behavior, its mechanism is unclear from this study and future studies are needed to verify how the venom exerts its antinociceptive action.

Estudos computacionais de esfingomielinases D: docking, dinâmica molecular e métodos híbridos QM/MM

Pós-graduação em Biofísica Molecular - IBILCE

The Effects of Ornamentation on Wolf Spider Foraging

ABSTRACT: As a secondary sexual trait that can increase reproductive success, ornamentation is believed to be costly for organisms to acquire and possess. This study investigates possible costs of ornamentation on wolf spider foraging by comparing foraging abilities of two male forms that differ in ornamentation upon maturation. The two male forms, found syntopically in a mixed population in Mississippi, USA, resemble two sibling species: Schizocosa ocreata, in which males develop large black brushes on their forelegs upon maturation, and Schizocosa rovneri, in which males lack ornamentation following maturation. Individuals of both forms participated in foraging trials as penultimates (juveniles) and as matures. Analyses were conducted to compare behaviors and determine changes in foraging abilities between male forms (non-ornamented vs. brush-legged) and between age groups (penultimate vs. mature). Most foraging behaviors of the two male forms during immaturity were similar with the exception that brush-legged males attacked more frequently than non-ornamented males. Brush-legged males attacked less, spent more time moving, and improved capture abilities as matures, while non-ornamented males retained similar trends for these behaviors with age. Additionally, while capture abilities improved with age among brush-legged males, killing abilities remained constant. This disparity was due to increased escapes made by captured prey items, possibly due to hindrances caused by brush presence preventing secure holds onto crickets. In summary, differences in foraging exist between brush-legged and non-ornamented males prior to sexual maturation, and the development of/presence of brushes appears to influence adult male foraging efficiency.

G93-1167 Spider Mite Management in Corn and Soybeans

This NebGuide describes the two common spider mites found in Nebraska corn and soybeans, their natural enemies and management. Two species of spider mites, the Banks grass mite and twospotted spider mite, commonly feed on Nebraska corn. Banks grass mites (BGM) feed almost exclusively on grasses, including corn and sorghum. Twospotted spider mites (TSM) not only feed on many species of grasses, but also on soybeans, fruit trees and a variety of vegetables and ornamental plants. Although these two species are somewhat similar in appearance, they differ in several biological characteristics and in their susceptibility to pesticides. Banks grass mites usually appear earlier in the season, feed mostly on the lower leaves of the corn plant, and in Nebraska are moderately susceptible to many of the commonly used miticides. On the other hand, TSM tend to appear in mid to late season, increase rapidly, feed over the entire plant, and often are not consistently controlled by available pesticides.

Estudos computacionais de esfingomielinases D: docking, dinâmica molecular e métodos híbridos QM/MM

Pós-graduação em Biofísica Molecular - IBILCE

Influence of Prey Size on the Capture of Social Wasps (Hymenoptera: Vespidae) by the Orb-Web Spider Nephilengys cruentata

The objective of the present study was to evaluate the plasticity of the hunting behavior of the spider Nephilengys cruentata (Araneae: Nephilidae) facing different species of social wasps. Considering that wasps can consume various species of spiders and that their poison can be used as defense against many predators, the effect of the corporal size of the prey was evaluated in the behavior of N. cruentata. Predation experiments were conducted using three species of social wasps of different sizes and the data registered in this research were compiled through annotations and filming of the hunting behavior of each spider, in relation to the offered prey. The results revealed that the size of the wasp and the sequential offer of prey change the hunting behavior of the spider, and prey of large size have high influence on this behavior.

Podochela meloi Sankarankutty, Ferreira & Cunha, 2001, a junior synonym of the spider crab Inachoides forceps A. Milne-Edwards, 1879 (Crustacea: Brachyura: Inachoididae)

Podochela meloi Sankarankutty, Ferreira & Cunha, 2001, originally described in the Inachidae MacLeay, 1838, was recently transferred to the Inachoididae genus Inachoides H. Milne Edwards & Lucas, 1842, based upon overall similarities. Placement of P. meloi in both Inachoididae and Inachoides is found to be supported by a number of synapomorphies as shown herein. Podochela meloi is shown to be a junior synonym of Inachoides forceps A. Milne-Edwards, 1879.

Investigation of the relationship between the structure and function of Ts2, a neurotoxin from Tityus serrulatus venom

Scorpion toxins targeting voltage-gated sodium (NaV) channels are peptides that comprise 6076 amino acid residues cross-linked by four disulfide bridges. These toxins can be divided in two groups (a and beta toxins), according to their binding properties and mode of action. The scorpion a-toxin Ts2, previously described as a beta-toxin, was purified from the venom of Tityus serrulatus, the most dangerous Brazilian scorpion. In this study, seven mammalian NaV channel isoforms (rNaV1.2, rNaV1.3, rNaV1.4, hNaV1.5, mNaV1.6, rNaV1.7 and rNaV1.8) and one insect NaV channel isoform (DmNaV1) were used to investigate the subtype specificity and selectivity of Ts2. The electrophysiology assays showed that Ts2 inhibits rapid inactivation of NaV1.2, NaV1.3, NaV1.5, NaV1.6 and NaV1.7, but does not affect NaV1.4, NaV1.8 or DmNaV1. Interestingly, Ts2 significantly shifts the voltage dependence of activation of NaV1.3 channels. The 3D structure of this toxin was modeled based on the high sequence identity (72%) shared with Ts1, another T. serrulatus toxin. The overall fold of the Ts2 model consists of three beta-strands and one a-helix, and is arranged in a triangular shape forming a cysteine-stabilized a-helix/beta-sheet (CSa beta) motif.

Solanum americanum as a reservoir of natural enemies of the tomato red spider mite, Tetranychus evansi (Acari: Tetranychidae)

Brazilian populations of the pathogenic fungus Neozygites floridana (Weiser & Muma) Remaudiere & S. Keller (Entomophthoromycotina: Entomophthorales) and the predatory mite Phytoseiulus longipes Evans (Acari: Phytoseiidae) are potential candidates for introduction into Africa for classical biological control of the tomato red spider mite, Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae). The efficiency of these natural enemies against T. evansi has been demonstrated under laboratory conditions, but little is known about their performance on native Solanaceae in the field. The American nightshade, Solanum americanum Mill., is native to the Americas and may serve as an alternative host plant for T. evansi and its natural enemies in the absence of tomato plants. In this work, we studied the population dynamics of T. evansi and its natural enemies on S. americanum in a screen house, semi-field and field plots in Recife, Pernambuco, Brazil, to evaluate the potential of natural enemies for controlling T. evansi. Of the four natural enemies found in association with T. evansi, only N. floridana and P. longipes were clearly associated with the reduction of the populations of T. evansi. Neozygites floridana was observed in a screen house, semi-field and field plots, but P. longipes was only detected in the semi-field plots. Increases in the population of T. evansi were always followed by increases in the density of one of these natural enemies, suggesting that they were important factors regulating T. evansi populations on S. americanum. The presence of this host plant near the release sites in Africa thus might increase the chances for the permanent establishment of these natural enemies.

Biochemical and enzymatic characterization of BpMP-I, a fibrinogenolytic metalloproteinase isolated from Bothropoides pauloensis snake venom

Snake Venom Metalloproteinases (SVMPs) are the most abundant components present in Viperidae venom. They are important in the induction of systemic alterations and local tissue damage after envenomation. In the present study, a metalloproteinase named BpMPI was isolated from Bothropoides pauloensis snake venom and its biochemical and enzymatic characteristics were determined. BpMPI was purified in two chromatography steps on ion exchange CM-Sepharose Fast flow and Sephacryl S-300. This protease was homogeneous on SOS-PAGE and showed a single chain polypeptide of 20 kDa under non reducing conditions. The partial amino acid sequence of the enzyme showed high similarity with other SVMPs enzymes from snake venoms. BpMPI showed proteolytic activity upon azocasein and bovine fibrinogen and was inhibited by EDTA, 1,10 phenanthroline and beta-mercaptoethanol. Moreover, this enzyme showed stability at neutral and alkaline pH and it was inactivated at high temperatures. BpMPI was able to hydrolyze glandular and tissue kallikrein substrates, but was unable to act upon factor Xa and plasmin substrates. The enzyme did not induce local hemorrhage in the dorsal region of mice even at high doses. Taken together, our data showed that BpMP-I is in fact a fibrinogenolytic metalloproteinase and a non hemorrhagic enzyme. (C) 2011 Elsevier Inc. All rights reserved.