Presence of myotropins in larval midgut extracts of lepidopteran insects: Manduca sexta, Agrotis segetum and Spodoptera exempta
1992
Yi, S.X. | Tirry, L. | Degheele, D.
Myotropic factors were found in larval midgut extracts of three lepidopteran species: Manduca sexta, Agrotis segetum and Spodoptera exempta. The myotropic activity detected in the midgut extract of M. sexta is much higher than those of the other two species. These biologically active factors were partially purified by reverse-phase C18 Sep-pak and HPLC fractionation on a micro-Bondapak Phenyl column. A heterologous Locusta migratoria oviduct bioassay was used to monitor the myotropic activity in all purification steps. There are at least eight active HPLC fractions in M. sexta and two in both A. segetum and S. exempta, which stimulated the spontaneous contraction of the locust oviduct in vitro. The results of pronase digestion and heat treatment (100 degrees C for 60 min) indicated that the myotropic factors present in the midgut extracts of these three species are heat-stable peptides since they were inactivated by pronase but not by boiling.
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