Characterization of genital tract growth factor‐like activity from testis sheaths and fat body of Heliothis virescens

Abstract

AbstractTestis sheaths and fat body from developing male pupae of Heliothis virescens synthesize soluble growth factor‐like products when exposed to 20‐hydroxyecdysone (20HE). These factors promote growth and development of the genital tract. Saline extracts of modified Grace's medium and 20HE‐treated testis sheaths and fat body were subjected to heat, freeze‐thaw, organic solvents, and low pressure size exclusion chromatography. Although extracts were stable to repeated freeze‐thawing, activity was lost after exposure to organic solvents; activities of fractions heavier than 6.5 KDa were inhibited by heating to 100°C. Size exclusion chromatography yielded 10 active testis extract fractions and 9 active fat body fractions. Although the approximate molecular weights of most of the extract fractions were similar, enzyme studies using protease, lipase, and α‐amylase indicated differences in the chemistry of active fractions derived from the two tissues. Active factors were inhibited by protease or lipase or both enzymes. © 1994 Wiley‐Liss, Inc.