Type-A allatostatins from the fall armyworm, Spodoptera frugiperda: molecular cloning, expression and tissue-specific localization

Abstract

The gene encoding the Spodoptera frugiperda allatostatin type-A peptide family (Y/FXFGL-amides) was isolated from S. frugiperda brain cDNA. The gene encodes a precursor of 231 amino acids containing nine (or ten) Y/FXFGL-a peptides that are tandemly arranged in three blocks. The comparison of the Spofr-AST A precursor with the respective precursor genes from two other lepidopteran species, Helicoverpa armigera and Bombyx mori, shows high homology in size, sequence (84 and 57%, respectively), and organisation of the allatostatins. One-step RT-PCR analysis using a Spofr-AST A-6 to A-9 probe shows that the gene is not only expressed as one transcript in the brain and midgut of larvae and adults in a time- and tissue-specific manner, but also in the reproductive tissues of adult S. frugiperda. Data confirm the nature of the allatostatin type-A peptides as brain/gut myoregulatory hormones, whereas their function(s) in ovaries, oviduct, and testes still have to be resolved. The cell-specific localization of the preprohormone expression, as demonstrated by whole mount in situ hybridization, confirms the overall distribution of the Spofr-AST A preprohormone as shown by RT-PCR and supports the pleiotropic functions of the peptides.