Biochemical characterization of a phospholipase A2 homologue from the venom of the social wasp Polybia occidentalis

Background: Wasp venoms constitute a molecular reservoir of new pharmacological substances such as peptides and proteins, biological property holders, many of which are yet to be identified. Exploring these sources may lead to the discovery of molecules hitherto unknown. This study describes, for the first time in hymenopteran venoms, the identification of an enzymatically inactive phospholipase A2 (PLA2) from the venom of the social wasp Polybia occidentalis. Methods: P. occidentalis venom was fractioned by molecular exclusion and reverse phase chromatography. For the biochemical characterization of the protein, 1D and 2D SDS-PAGE were performed, along with phospholipase activity assays on synthetic substrates, MALDI-TOF mass spectrometry and sequencing by Edman degradation. Results: The protein, called PocTX, was isolated using two chromatographic steps. Based on the phospholipase activity assay, electrophoresis and mass spectrometry, the protein presented a high degree of purity, with a mass of 13,896. 47 Da and a basic pI. After sequencing by the Edman degradation method, it was found that the protein showed a high identity with snake venom PLA2 homologues. Conclusion: This is the first report of an enzymatically inactive PLA2 isolated from wasp venom, similar to snake PLA2 homologues.

Biochemical characterization of a phospholipase A2 homologue from the venom of the social wasp Polybia occidentalis

Wasp venoms constitute a molecular reservoir of new pharmacological substances such as peptides and proteins, biological property holders, many of which are yet to be identified. Exploring these sources may lead to the discovery of molecules hitherto unknown. This study describes, for the first time in hymenopteran venoms, the identification of an enzymatically inactive phospholipase A2 (PLA2) from the venom of the social wasp Polybia occidentalis. Methods: P. occidentalis venom was fractioned by molecular exclusion and reverse phase chromatography. For the biochemical characterization of the protein, 1D and 2D SDS-PAGE were performed, along with phospholipase activity assays on synthetic substrates, MALDI-TOF mass spectrometry and sequencing by Edman degradation. Results: The protein, called PocTX, was isolated using two chromatographic steps. Based on the phospholipase activity assay, electrophoresis and mass spectrometry, the protein presented a high degree of purity, with a mass of 13,896. 47 Da and a basic pI. After sequencing by the Edman degradation method, it was found that the protein showed a high identity with snake venom PLA2 homologues. Conclusion: This is the first report of an enzymatically inactive PLA2 isolated from wasp venom, similar to snake PLA2 homologues.(AU)

Promotion of thermoregulatory insulation in nests of neotropical wasps by building extra-combs with empty cells / Promoção de isolamento térmico em ninhos de vespas neotropicais pela construção de favos com células vazias

We examined the hypotheses that the empty combs of Polybia occidentalis Olivier (Hymenoptera: Vespidae) nest insulate the inside of the nest. To examine this hypotheses, two kinds of temperature measurements were carried out: 1) with the outer comb of the nest intact (Control) and 2) removed (Treatment), using a large and a small nest. In the large nest, the daily nest temperatures (outer part, Tn1; inner part, Tn2) in Control were lower by 0.6°C (Tn1) and 1.2°C (Tn2) than those in Treatment, because of a higher ambient temperature (Ta) throughout temperature assessment in Treatment. However, the excess temperature (Tn - Ta) in Control was higher than that in Treatment. The value was higher by 0.7°C at Tn1 and 0.1°C at Tn2. In the small nest, the excess temperature in outer part was similar between experiments, while that in inner part of Control was lower than that of Treatment. The temperature fluctuation in the nests was lower in the Control than that in Treatment both the outer and inner part of the comb. We conclude that the unused comb is ecologically invaluable for raising and protecting the brood from extreme changes in ambient temperature during the winter period, because it helps not only keeping a higher nest temperature but also decreasing the temperature fluctuation around the brood combs. In addition, such a high temperature may influence the performance of adult wasps.

Examinou-se a hipótese de que os favos vazios dos ninhos de Polybia occidentalis Olivier (Hymenoptera: Vespidae) atuam como isolamento térmico dos elementos internos da colônia. Para avaliar essa hipótese dois tipos de medidas de temperatura foram tomadas: 1) com o favo externo intacto (Controle) e 2) removido (Tratamento), usando um ninho grande e um ninho menor. As temperaturas diárias no ninho grande (parte externa Tn1; parte interna Tn2), no Controle, foram 0,6°C (T n1) e 1,2°C (Tn2) mais baixas que aquelas do Tratamento, devido à temperatura ambiente (Ta) mais alta durante todo o período avaliado. Entretanto, a temperatura excedente (Tn - Ta) no Controle foi mais alta que no Tratamento. O valor foi 0,7°C mais alto em Tn1 e 0,1°C em Tn2. No ninho menor, a temperatura excedente na parte externa foi semelhante entre os experimentos, e na parte interna a temperatura do Controle foi inferior à do Tratamento. A flutuação térmica nos ninhos foi menor no Controle que no Tratamento, tanto na parte externa quanto interna dos favos. Conclui-se que o favo sem uso é ecologicamente muito importante para criar ou proteger a cria das alterações extremas de temperatura ambiente no inverno, uma vez que ele auxilia na manutenção de temperatura alta no ninho e também no decréscimo da flutuação de temperatura ao redor dos favos de cria. Além disso, essas temperaturas mais altas influenciam as atividades dos adultos.