Sylvia M. Lucas

Spiders in Brazil

Descriptions of the principal venomous spiders in Brazil, of the genera Phoneutria, Loxosceles, Latrodectus and Scaptocosa, are given, together with a list of species and their geographical distribution. Detailed information on their habitat, behaviour and venom quantity, symptomatology of human accidents and epidemiology is given and recommendations are made for the prevention of accidents. General observations are made on the most common mygalomorph spiders.

Tc1, from Tityus cambridgei, is the first member of a new subfamily of scorpion toxin that blocks K+-channels

A new peptide, Tc1, containing only 23 amino acids closely packed by three disulfide bridges was isolated from the Amazonian scorpion Tityus cambridgei. It blocks reversibly the Shaker B K+‐channels with a K d of 65 nM and displaces binding of noxiustoxin to mouse brain synaptosome membranes. It is the shortest known peptide from scorpion venom that recognizes K+‐channels and constitutes a new structural subfamily of toxin, classified as alphaKTx 13.1.

Mygalomorph spider bites: a report on 91 cases in the state of São Paulo, Brazil.

From 1966 to 1991 91 cases of bites due to mygalomorph spiders were recorded at the Hospital Vital Brazil, Instituto Butantan, São Paulo, Brazil, representing less than 1% of all spider bites. The diagnosis was confirmed by positive identification of the spider involved. Envenoming is generally mild, the main symptom is local pain, and there is minor oedema and erythema. The data confirm the assumption that these nonaggressive spiders pose no health problem.

The genomic region encoding toxin gamma from the scorpion Tityus serrulatus contains an intron

The gene encoding toxin gamma from the scorpion, Tityus serrulatus, was amplified by PCR from genomic DNA employing synthetic oligonucleotides designed from the reported cDNA sequence. The nucleotide sequence of this gene reveals the presence of an intron of 475 base pairs (bp) which interrupts the region that encodes the signal peptide of the precursor toxin. A comparison of the intron boundary sequences of the gamma toxin gene with ones from other arachnid genes is also presented.

Scorpion toxins from Tityus cambridgei that affect Na+-channels

By means of high performance liquid chromatography (HPLC) the soluble venom of the Amazonian scorpion Tityus cambridgei was fractionated into over 50 different components. Four toxic and/or lethal peptides to mice were obtained in pure form and sequenced. Mass spectrometry analysis showed molecular weights of 7310, 7151, 7259 and 7405, respectively, for toxins Tc48a, Tc49a, Tc54 and Tc49b. The N-terminal amino acid sequence was obtained for the three first toxins mentioned, whereas the full primary structure was determined for Tc49b. It contains 64 amino acid residues, closely packed by four disulfide bridges. Sequence comparison analysis showed similarities around 50% with other toxins from scorpions of the genus Tityus of Brazil. It is lethal to mice at doses of 20 microg per 20 g mouse. The toxin was shown to affect the Na(+)-currents permeability of rat cerebellum granular cells in culture. Almost a complete elimination of current was observed with 100 nM toxin concentration. This effect was partially reversible. Furthermore, this toxin does not modify the function of the Shaker B K(+)-channels expressed on Sf9 cells, nor does it modify the Na(+)-channel function in a similar manner as those reported for the alpha-scorpion toxins purified from other scorpions.

Effects of a centipede venom fraction on insect nervous system, a native Xenopus oocyte receptor and on an expressed Drosophila muscarinic receptor.

Centipede venoms are complex protein mixtures; very few is known about their pharmacological actions. Application of a Scolopendra sp. venom fraction (SC1) on the cockroach giant axon induced an increase in the leak current correlated with a decrease in the membrane resistance, suggesting the presence in SC1 of components opening non-specific pores in the axonal membrane. On a cockroach central cholinergic synapse, microinjection of SC1 induced a small transient depolarization of the postsynaptic membrane, followed by a slow stable depolarization and a drastic decrease in the evoked subthreshold excitatory postsynaptic potential amplitude. A pretreatment of the ganglion with atropine or scopolamine reduced the amplitude of the SC1-induced depolarizing wave, suggesting a possible cholinergic muscarinic target. On control Xenopus oocytes, SC1 induced an inward oscillatory Ca2(+)-dependent Cl- current mediated through the activation of native lysophosphatidic acid receptors (LPAr). Indeed, pretreatment of oocytes with 1 microM N-palmitoyl-tyrosine phosphoric acid, a selective competitive antagonist of LPAr, decreased responses to SC1 by 70%. Application of SC1 to oocytes expressing a cloned Drosophila muscarinic receptor (Dml) induced a biphasic response comprising: (1) a large fast Cl- current that was abolished by pretreatment with atropine and scopolamine and (2) a slow and small oscillating Cl- current corresponding to the response observed in control oocytes. These observations confirm the presence of muscarinic agonists in SCI and reveal their direct action on an insect muscarinic receptor subtype homologous to mammalian M1-M3 receptors.

Litter dwelling mygalomorph spiders (Araneae: Microstigmatidae, Nemesiidae) from Araucaria forests in southern Brazil, with the description of five new species

Six mygalomorph spiders species belonging to two families, were collected in the Centro de Pesquisa e Conservacao da Natureza Pro-Mata, Sao Francisco de Paula, state of Rio Grande do Sul, Brazil. Five of those species, five are new. Microstigmatidae: Xenonemesia araucaria sp. nov., males differ from those of X. platensis Goloboff, 1988 and X. otti Indicatti, Lucas & Brescovit, 2007 by the curved and very long embolus in the male palp. Females differ from the remaining species of the genus in the seminal receptacle very long and sinuous or twisted. Nemesiidae: Acanthogonatus ericae sp. nov. - males resemble those of A. tacuariensis (Perez-Miles & Capocasale, 1982) and A. quilocura Goloboff, 1995 by the serrated, curved and long embolus but are distinguished by the presence of a flange on the apex of the embolus. Females differ from the remaining Acanthogonatus by the short copulatory ducts, arising from the apex of the basal dome. Stenoterommata arnolisei sp. nov. is distinguished from the remaining species of the genus by the large sub-apical area of bulb, with a great number of keels, extending to the median region in the male palp and by the long copulatory ducts and spermathecae arising from internal border of basal dome in the female genitalia. S. grimpa sp. nov.: males resemble those of S. arnolisei sp. nov. by the shape of the palpal bulb and by the short embolus, but differ in the keels, restricted to the apical region. Females differ from remaining Stenoterommata by the presence of two spermathecae in the rounded fused basal dome. S. curiy sp. nov.: males resemble those of S. grimpa sp. nov. by the shape of palpal bulb and the very short embolus, but differ by the translucid keels restricted to the larger distal region. The presence of S. palmar Goloboff, 1995 is confirmed for Brazil. Males of S. palmar are distinguished from the remaining species of the genus by the long, slender and slightly distally curved embolus. Females are distinguished by the single spermathecae arising from the basal third or median area of the long and triangular basal dome. All spiders were collected with pitfall trapping at six distinct areas (two Araucaria forest areas, two secondary forests and two Pinus spp. Silvicultural plantations) over a period of 20 months. Abundance data between areas was compared for S. arnolisei sp. nov. and X. araucaria sp. nov. based on the mean catches of spiders in each area. No clear habitat preference was shown for each of the species, suggesting broad habitat tolerances. Phenological data were obtained through the abundance in each trapping period; results suggest an overwintering reproductive pattern for S. arnolisei sp. nov. and a spring-summer pattern for X. araucaria sp. nov.

Maintenance of scorpions of the genus Tityus koch (Scorpiones, Buthidae) for venom obtention at Instituto Butantan, São Paulo, Brazil

This work presents the experience of the Laboratory of Arthropods at Instituto Butantan, which maintains scorpions in captivity in order to obtain the venom used in the production of anti-arachnid serum. Between 1993 and 2000, the laboratory received 24.781 specimens of Tityus serrulatus in order to obtain poison for the production of anti-scorpion serum. In the first extraction, performed by electrical stimulation, the animals gave an average quantity of 0.4 mg venom per specimen. Animal acquisition and involved professional safety are considered. In addition, the captivity, handling and feeding techniques are described, as well as the method and equipment used for venom extraction. It shows the importance of regular campaigns, offering information to the general population in order to motivate these to catch and send alive scorpions to the Institute to assuring a regular entrance of scorpions.

Isolation, characterization and biological properties of two kinin-like peptides (peptide-S and peptide-R) from Scaptocosa raptoria venom

Two peptides with kinin-like biological properties were isolated by chromatography on a Sephadex G-10 column followed by high-performance liquid chromatography, from the venom of the spider Scaptocosa raptoria. The isolated peptides (peptide-S and peptide-R) were shown to cause contraction on the isolated guinea-pig ileum at amounts equivalent to those shown by bradykinin. Both peptides relaxed the isolated rat duodenum, increased the capillary permeability, caused decreasing and biphasic effect of the arterial blood pressure in conscious rats and induced oedema in the rat paw. The peptides had activity and structural similarities to other peptides (kinin-like) isolated from venoms. The complete amino acid analysis gave peptide-S a structure with 36 amino acid residues and peptide-R 22 amino acid residues. The mol. wts were estimated to be in the range of 4000 and 2870, respectively.

Description of Guyruita gen. nov. and two new species (Ischnocolinae, Theraphosidae)

The genus Guyruita gen. nov. and two new species from Brazil are described. Holothele waikoshiemi (Bertani & Araujo, 2005) from Venezuela is transferred here to the new genus. Guyruita gen. nov. differs from the remaining Ischnocolinae by the following features: labium densely occupied by a lot of cuspules (more than 100), intercheliceral intumescence absent, posterior sternal sigilla remote from margin, tarsal claws without teeth, tarsal scopula I-II undivided (tarsus II with a line of sparse setae, which does not divide the scopula), III-IV divided.