Allatotropic and allatostatic activities in extracts of brain and the effects of Manduca sexta allatotropin and Manduca sexta allatostatin on juvenile hormone synthesis in vitro by corpora allata from the Eri silkworm, Samia cynthia ricini

Abstract

Abstract. Both allatotropic and allatostatic activities were found in crude extracts of brain from adult and larval Eri silkworm, Samia cynthia ricini, but it seems that allatotropic activity dominates in each stage. There was a high level of allatotropic activity in the crude extract of brain from newly emerged female adults, but allatostatic activity appeared in the bioassay when excessive amounts of crude extracts of brain were added. Crude extracts of brain from premoulting fourthinstar larvae and from newly ecdysed fifth-instar larvae exhibited allatotropic activities, whereas extracts of brain from the second and third day of the fifthinstar larvae inhibited juvenile hormone (JH) release slightly. Allatotropic activity from the brains of adults and larvae stimulated both adult and larval corpora allata (CA) to synthesize JH. Manduca sexta allatotropin (AT) (Mas-AT) and M. sexta allatostatin (AST) (Mas-AST) also stimulated and inhibited both adult and larval S. cynthia ricini CA to synthesize JH, respectively. Higher concentrations of Mas-AT (10 À4 or 10 À3 M) showed an inhibitory effect on adult CA. CA from newly emerged female adults were the most sensitive to inhibition by Mas-AST, whereas CA from female pharate adults at about 6 h before adult emergence were the most sensitive to stimulation by Mas-AT and S. cynthia ricini brain allatotropic activity. An extract of brain and Mas-AT induced some of the non-active female pharate adult CA at 12 h before emergence to synthesize a small amount of JH.

Starvation influences allatotropin gene expression and juvenile hormone titer in the female adult oriental armyworm, Mythimna separata

“…Juvenile hormone (JH) plays an important role in determining the migratory morph (Zera and Cisper, 2001;Zera, 2004) and regulating reproductive and migratory activities in adult insects (Cusson et al, 1990;Zera and Denno, 1997). JH level was regulated by allatostatins (ASTs) and allatotropins (ATs), neuropeptides that modulate JH titers in response to environmental cues (Audsley et al, 1999;Li et al, 2002) via their action on corpora allata (CA). A Manse-AT identified from Manduca sexta stimulates JH biosynthesis of M. sexta and several other moth species (Teal, 2002;Koladich et al, 2002).…”

Biochemical and molecular characterization of allatotropin and allatostatin from the Eri silkworm, Samia cynthia ricini

“…Both AT and AST activities were observed in the brain extract from S. cynthia ricini (Li et al, 2002b). To confirm our assumption that Samcri-AT and -AST are homologs to Manse-AT and -AST, crude extract of brain from newly emerged female adult S. cynthia ricini was purified with the four-step procedure.…”

“…Both AT and AST activities were detected in the brain extracts, and Manse-AT and -AST were shown to stimulate and inhibit, respectively, JH synthesis in isolated CA (Li et al, 2002b). In the present study, we characterize Samcri-AT and -AST with biochemical and molecular techniques.…”

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In a previous study, allatotropic and allatostatic activities were observed in brain extract from the Eri silkworm, Samia cynthia ricini (Samcri) [Li, S., Jiang, R.-J., Cao, M.-X., 2002b. Allatotropic and allatostatic activities in brain extracts of the Eri silkworm, S. cynthia ricini, and the effects of Manduca sexta allatotropin and M. sexta allatostatin on juvenile hormone in vitro.

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“…Allatoregulatory activity was evaluated as experimental/control -1 (Li et al, 2002b). AT and AST factors were isolated and purified through the following four steps:…”