CYTOGENETIC STUDIES WITH EMBRYOS OF THE ARMED SPIDER Phoneutria nigriventer (KEYSERLING, 1891) (ARACHNIDA: CTENIDAE)

LAGES C.P. (1,2), SILVA L.M. (1), VALENTIM C.L.L. (3), BABA E.H. (3), FORTES-DIAS C.L.(1)

(1) Lab. Molecular and Cell Biology, Research and Development Center (DPD), Fundação Ezequiel Dias (FUNED), Belo Hte., MG; (2) Pontifícia Universidade Católica  de  Minas  Gerais ( PUC-MG),  Belo  Hte, MG; (3)  Dep. Pharmacology, Universidade Federal de Ouro Preto (UFOP), Ouro Preto, MG, Brazil.

Phoneutria spiders are solitary and very aggressive animals, popularly known as “armed” or “banana” spiders. Amongst the four species of Phoneutria (PERTY, 1833) that occur in Brazil, Phoneutria nigriventer (KEYSERLING, 1891) is the most important in public health (1). Although there are several reports focusing on the biochemical and pharmacological properties of P. nigriventer venom, cytogenetics studies on these spiders are lacking. Aiming to identify the loci of specific toxin genes of P. nigriventer, we started by preparing embryonic chromosomes. Cocoons were collected at the municipality of Santa Barbara (MG) together with adult females of the same species. After external chemical cleaning, the cocoons were opened and the eggs therein were disaggregated by mechanical molecular sieving. Egg cells were immersed in CMRL medium containing colchicine and treated hypertonic 0.075 M KCl. After fixation with methanol:acetic acid (3:1), the cells suspension was dropped on glass slides and flamed for chromosome exteriorization. Staining was performed with acetic orcein and the material treated for G- and C- chromosome banding. The embryonic cells displayed 30 acrocentric chromosomes with two hyper chromic bands in the chromatids. Our next step will be devoted to the identification of the loci of specific toxin genes.

KEY WORDS: armed spider, Phoneutria, Phoneutria nigriventer, chromosome, C-banding, G-banding.

1- Schenberg, S. & Pereira-Lima, F.A. (1976) Venoms of Ctenidae. In: Arthropod Venoms. Bettini, S., Ed., New York: Springer.

FINANCIAL SUPPORT: CNPq and FAPEMIG

CORRESPONDENCE TO: LUCIANA M. SILVA, Laboratório de Biologia Molecular e Celular, DCB/DPD, FUNED. Phone: 31 3371 9436; e-mail: lucianams@funed.mg.gov.br