title: Injection of Dip-allatostatin or Dip-allatostatin pseudopeptides into mated female Diploptera punctata inhibits endogenous rates of JH biosynthesis and basal oocyte growth.
abstract: Studies on the catabolism of allatostatins (ASTs) provided the rationale for the design of a series of Dip-allatostatin-derived pseudopeptide mimetic analogues. In vitro, the Dip-ASTs and pseudopeptides show varying degrees of resistance to catabolism and all show significant inhibition of juvenile hormone (JH) biosynthesis. This study was undertaken to determine whether potent Dip-ASTs and/or their pseudopeptide mimetic counterparts caused 'allatostatic' effects in vivo following injection into mated female Diploptera punctata. Animals injected with aqueous solvent or Dip-AST 7(1-7) N-terminal fragment, which excludes the active core region of the ASTs, were used as controls. An in vitro radiochemical assay revealed that injection of Dip-AST 5, 7 or pseudopeptide analogues 397-2 or AST(b)&phi;2 significantly inhibited the biosynthesis of JH (P<0.05). The results also indicate that basal oocyte growth was significantly inhibited by injection of these same compounds, with the exception of Dip-AST 7 (P<0.05). Analogues 396-1 and 419 did not significantly inhibit rates of JH biosynthesis but did significantly inhibit the growth of basal oocytes. Analyses of feeding, excretion and food absorption/utilization patterns of these same animals suggested that these compounds are not toxic to the insect; rather they directly inhibit the biosynthesis of JH by the corpora allata, and reduce the rate of growth of basal oocytes. Disruption of critical reproductive and/or developmental processes by pseudopeptide analogues of the ASTs could provide novel and selective strategies for future insect pest management.
authors.affiliation: Department of Zoology, University of Toronto, M5S 3G5, Toronto, On, Canada.
authors.forename: C S
authors.initials: CS
authors.lastname: Garside
authors.forename: R J
authors.initials: RJ
authors.lastname: Nachman
authors.forename: S S
authors.initials: SS
authors.lastname: Tobe
mesh_terms: D000818:Animals; D003058:Cockroaches; D005216:Fat Body / Q000378:metabolism; D005247:Feeding Behavior; D005260:Female; D006727:Hormone Antagonists / Q000378:metabolism*; D007605:Juvenile Hormones / Q000096:biosynthesis*; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D009865:Oocytes / Q000254:growth & development* / Q000378:metabolism; D012726:Sexual Behavior, Animal; D012995:Solubility
chemical_list: D006727:Hormone Antagonists; D007605:Juvenile Hormones; D009479:Neuropeptides; C076523:allatostatin