Estudo da ação do inibidor de proteinase de Adenanthera pavonina sobre o desenvolvimento e atividade das proteinases intestinais de lagartas de Diatraea suchharalis (FABR., 1794) / Study of proteinase inhibitor action from Adenanthera pavonina on the development and midgut proteinase activities of the Diatraea sachharalis larvae (FABR., 1794)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Phytophatogous insects and other animals use digestive enzymes, such as amylases and proteinases to process the nutrients obtained from the plants necessary for their development. The sugarcane borer Diatraea saccharalis is the major pest of sugarcane in Brazil and other South American countries. Plants synthesize a variety of molecules, including proteinase inhibitors (PIs), to defend themselves against attack by insects. PIs are polypeptides that are able to bind to insect midgut proteolytic enzymes, rendering them inactive by competitive inhibition. This process leads to a limitation of essential amino acids in protein synthesis, and thus, to reduction in growth and development. The predominance of sugarcane-borer digestive serine proteinases has motivated the discovery of PIs with the ability to reduce the digestion process. In this report, the pure inhibitor from seeds of Adenanthera pavonina ? ApTI was used in bioassay and its toxic activity on D. saccharalis was determined. The ingestion of ApTI did result in a significant reduction in larval survival and weight. To examine the protein effects on insect, the midgut proteinases of D. saccharalis larvae reared on artificial PI-free diet and on a diet containing ApTI at 0.05% were compared by using enzymatic assays and polyacrilamide gel electrophoresis. The fourth instar larvae reared on diet containing ApTI showed a decrease in tryptic activity of gut and faeces, as confirmed by enzymatic assays and by polyacrilamide gel eletrophoresis. The results from dietary utilization experiments realized with D. saccharalis larvae presented a reduction in efficiency of conversion of ingested food (ECI) and digested food (ECD) and an increase in metabolic cost (CM). In addition, the tryptic activity in ApTI-fed larvae was sensitive to ApTI. These results suggest that ApTI have a potential antimetabolic effect when ingested by D. saccharalis.

ASSUNTO(S)

proteinase inhibitors broca-da-cana-de-açúcar inibidores de proteinase diatraea saccharalis olho-de-boi adenanthera pavonina

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