RESUMO
The venom gland of queens of Apis mellifera was examined through light and transmission electron microscopy and subjected to electrophoretic analyses. Virgin queens exhibited prismatic secretory cells containing large amounts of rough endoplasmic reticulum with dilated cisternae, open secretory spaces, numerous vacuoles and granules scattered in the cytoplasm, and spherical nuclei with numerous nucleoli. The secretion produced was non-refringent under polarized light and the electrophoretic analysis of glandular extracts revealed five main protein bands. In mated queens, the venom gland exhibited a high degree of degeneration. Its secretion was refringent under polarized light and one of the main bands was absent in the electrophoretic pattern obtained. The morphological aspects observed are in agreement with the function of this gland in queens, given that virgin queens use venom in battles for the dominance of the colony, a situation that occurs as soon as they emerge, while fertilized queens rarely use venom.
Assuntos
Venenos de Abelha/metabolismo , Abelhas/anatomia & histologia , Abelhas/fisiologia , Glândulas Exócrinas/metabolismo , Glândulas Exócrinas/ultraestrutura , Animais , Venenos de Abelha/análise , Abelhas/ultraestrutura , Eletroforese , Feminino , Fertilidade , Microscopia , Microscopia Eletrônica de TransmissãoRESUMO
The crude aqueous extract from the leaves of Casearia sylvestris, a plant found in Brazilian open pastures, was assayed for its ability to inhibit phospholipase A2 (PLA2) activity and some biological activities of bee and several snake venoms, and of a number of isolated PLA2s. The extract induced partial inhibition of the PLA2 activity of venoms containing class I, II and III PLA2s. When tested against the purified toxins, it showed the highest efficacy against class II PLA2s from viperid venoms, being relatively ineffective against the class I PLA2 pseudexin. In addition, C. sylvestris extract significantly inhibited the myotoxic activity of four Bothrops crude venoms and nine purified myotoxic PLA2s, including Lys-49 and Asp-49 variants. The extract was able to inhibit the anticoagulant activity of several isolated PLA2s, with the exception of pseudexin. Moreover, it partially reduced the edema-inducing activity of B. moojeni and B. jararacussu venoms, as well as of myotoxins MjTX-II and BthTX-I. The extract also prolonged the survival time of mice injected with lethal doses of several snake venoms and neutralized the lethal effect induced by several purified PLA2 myotoxins. It is concluded that C. sylvestris constitutes a rich source of PLA2 inhibitors.