Identification and neutralization of biological activities in the venoms of Loxosceles spiders

The biological activities of the venom of three species of spiders of the genus Loxosceles were studied (L. gaucho, L. laeta and L. intermedia). The dermonecrotic and lethal activities are shared by all three Loxosceles venoms. Only low levels of proteolytic, myotoxic and phospholipase A2 activities were demonstrable even when a large amount of venom was used. No direct hemolytic activitiy was detected. L. intermedia venom was the most lethal (LD50 0.48 mg/kg), the L. laeta venom was the least lethal (LD50 1.45 mg/kg) whereas L. gaucho venom showed an intermediate value (LD50 0.74 mg/kg). The anti-Loxosceles serum used (anti-arachnidic serum) was able to neutralize the most important activities (i.e., dermonecrotic and lethal activities) of the three venoms. SDS-PAGE and immunoblotting using the anti-arachnidic serum showed that almost all venom antigens were recognized by this antiserum. The possible mechanisms of action of the Loxosceles venom are discussed.

The evolution of scorpionism in Brazil in recent years

In this paper further information concerning the ecological and biogeographical aspects of scorpionism is presented. Some of the information already outlined in three previous publications (10,14,16) is assessed, and new data given concerning the pattern of distribution presented by Tityus serrulatus in Brazil. Some new ideas are also proposed regarding the possible evolutionary advantages and disadvantages of parthenogenesis versus sexuality in both the short-term and the long-term.

Antigenic cross-reactivity among the venoms from several species of Brazilian scorpions

The venoms of seven species of scorpions living in different regions of Brazil were analysed with regard to their lethality, antigenic cross-reactivity and ability to induce antibody production. In mice, the tested scorpion venoms can be grouped as: (a) highly toxic: Tityus stigmurus Thorell (), Tityus bahiensis (Perty) , Tityus serrulatus Lutz and Mello (, and Tityus costatus (Karsch) ; (b) moderately toxic: Tityus cambridgei Pocock ; and (c) practically nontoxic: Rhopalurus agamemnon (Koch) , and Brotheas amazonicus Lourenço . On electrophoresis the venoms showed many protein bands displayed along the chromatogram, most of them cross-reacting in immunoelectrophoresis and immunoblotting using horse anti-T. serrulatus, anti-T. bahiensis or anti-T. serrulatus + T. bahiensis sera as probes. The antibodies present in these antivenoms combine with venom components as measured in vitro by the ELISA assay, and neutralize their lethal effects in vivo. These results indicate that horse antivenoms against a mixture of T. serrulatus and T. bahiensis venoms or only against T. serrulatus venom yield an antibody population able to neutralize the toxic effects found in all venoms studied.

Loxoscelismo: estudo de 242 casos (1980-1984) / Loxoscelism: study of 242 cases (1980-1984)

Foram analisados 242 acidentes atribuídos a aranhas do gênero Loxosceles Heinecken & Lowe atendidos no Hospital Vital Brazil do Instituto Butantan (1980-1984). L. gaucho Gertsch foi o agente agresssor mais comum e a espécie capturada com maior frequência nos locais de acidente vistoriados. L. laeta e L. intermedia Mello-Leitäo também estiveram representados no material estudado. Noçöes de reconhecimento e biologia dessas aranhas assim como a distribuiçäo geográfica das espécies brasileiras foram incluídas, para orientaçäo de médicos e pessoal relacionado a acidentes por animais peçonhentos. Os sinais característicos de síndrome loxoscélica e sua frequência na casuística em estudo foram mencionados e uma comparaçäo foi feita com dados correspondentes encontrados na literatura sulamericana