Caracterização e Imunolocalização das Principais Enzimas Digestivas do Predador Podisus nigrispinus (Heteroptera: Pentatomidae)

• Ano de defesa: 2010
• Autor(a) principal: Fialho, Maria do Carmo Queiroz
• Orientador(a): Serrão, José Eduardo
• Banca de defesa: Pilon, Anderson Martins , Samuels, Richard Ian
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Biologia Celular e Estrutural
• Departamento: Análises quantitativas e moleculares do Genoma; Biologia das células e dos tecidos
• País: BR
• Palavras-chave em Português: Digestão; Predador
• Palavras-chave em Inglês: Digestion; Predator
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL
• Link de acesso: http://locus.ufv.br/handle/123456789/243

Considering the importance of the predator Podisus nigrispinus in programs of biological control of pests and the poor studies on the digestive enzymes in Hemiptera, this study aimed to identify, locate and characterize the major digestive enzymes of the salivary glands and midgut of P. nigrispinus. Adult males of P. nigrispinus were dissected and the salivary glands and midgut (divided into anterior, middle and posterior) subjected to enzyme tests for amylase, aminopeptidase, cathepsin L, trypsin and α-glucosidase. These enzymes were pre-purified and immunolocalized in the midgut regions. The pH was 6.0 in salivary gland and 5.6, 5.7 and 5.8 in the anterior, median and posterior regions of the midgut, respectively. The specific activity of enzymes in the salivary glands and midgut were respectively: amylase 0.01, 21 mU / mg, aminopeptidase 0.19, 3 mU / mg, cathepsin L 16, 3800 U / mg and α-glucosidase 0.27, 147 mU / mg protein. Trypsin was not active in the midgut, whereas in salivary gland its specific activity was 7 U / mg protein. Cathepsin L was the major proteinase in P. nigrispinus and showed two peaks of activity with optimum pH 5.5 and molecular mass of 14 and 17 kDa and Km 32 and 11 mM. Amylase, aminopeptidase, α-glucosidase had an optimum pH of 5.1, 5.5, 5.8, Km of 0.1%, 0.03, 5 mM and the molecular mass of 43, 125 and 90 kDa respectively. One hour after feeding, P. nigrispinus showed differences in activity of all enzymes tested and remained similar at other periods after feeding. The biochemical and immunolocalization data showed that the amylase, aminopeptidase and α-glucosidase membrane enzymes were more active in the anterior midgut, already in the middle and posterior all the enzymes were active, but with a higher activity of cathepsin L and soluble α-glucosidase. These data show that the initial digestion of carbohydrates begins in the anterior midgut and ends at the anterior and middle midgut, whereas digestion of proteins has its beginning in the middle, and ends at the anterior midgut, suggesting that the perimicrovilllar membrane play a role in compartmentalization of digestion in which the anterior midgut is related to water absorption and amino acid uptake obtained from xylem in this zoophytophagous insects.