Effect of the brain and suboesophageal ganglion on pupal development in Helicoverpa armigera through regulation of FXPRLamide neuropeptides

Recent studies in Helicoverpa armigera report a novel role for diapause hormone (DH), pheromone biosynthesis activating neuropeptide (PBAN) and three other FXPRLamide neuropeptides secreted from suboesophageal ganglion (SG) in terminating pupal diapause. In the present paper, we investigated the role of these five FXPRLamide family neuropeptides on pupal development. Although removal of SG could not make nondiapause-destined pupae enter diapause-like status, it did make them eclose approximately 0.6-1.2 days later when compared with the controls. The results of competitive ELISAs showed a high level of FXPRLamide titer in the hemolymph of the SG-removed pupae and this may be due to the expression of the DH-PBAN gene in tissues other than SG. DH-PBAN mRNA and peptides were also detected in the thoracic ganglia (TGs) by RT-PCR and immunocytochemistry. The expression of DH-PBAN gene in the TGs of the SG-removed pupae is significantly higher than that in normal pupae by quantitative PCR and immunocytochemistry. Decerebration experiments proved that the decerebrated pupae could enter diapause-like status through down-regulation of FXPRLamide titer in hemolymph. Our studies confirm that the brain plays an important role in the determination of pupal development by regulating the synthesis and release of FXPRLamide neuropeptides in H. armigera. Thus, the function of FXPRLamide peptides in H. armigera is closely correlated with pupal development.     

家蚕滞育激素－性信息素合成激活肽基因的表达

家蚕滞育激素－性信息素合成激活肽基因的表达徐卫华（中国农业科学院蚕业研究所,江苏镇江,２１２０００）山下兴亚（名古屋大学农学院,日本名古屋,４６４－０１）关键词滞育激素－性信息素合成激活肽基因;发育阶段;表达;家蚕昆虫是地球上最繁盛的物种,占地球上生...     

Cloning and expression of the cDNA encoding the FXPRL family of peptides and a functional analysis of their effect on breaking pupal diapause in Helicoverpa armigera

Diapause hormone (DH) and pheromone biosynthesis activating neuropeptide (PBAN) are encoded by a single mRNA in the suboesophegeal ganglion (SG) and are responsible for induction of embryonic diapause in Bombyx mori and sex pheromone biosynthesis in lepidopteran insects. PBAN cDNA analyses revealed that the DH-like peptide is present in several species that have a pupal diapause. However, the function of the DH-like peptide remains unknown. In the present study, we cloned the cDNA encoding DH-PBAN in Helicoverpa armigera utilizing the rapid amplification of the cDNA ends method. The nucleotide se quence analysis revealed that the longest open reading frame of this cDNA encodes a 194-amino acid precursor protein that con tains a 33-aa PBAN, a 24-aa DH-like peptide, and three other neuropeptides, all of which have a common C-terminal pentapeptide motif FXPR/KL ( X=G, T, S). A homology search showed that H. armigera DH-like and PBAN are highly homologous to those from other insects. Northern blot analysis demonstrated a single message RNA corresponding to the size of Har-DH-PBAN cDNA from pupal SG with significantly higher expression in the SG of nondiapause pupae than diapausing pupae. Western blot analysis showed DH-like peptide expression from SG of both males and females. When DH-like peptide was injected into nondiapause larvae and pupae, it did not induce diapause, but rather efficiently broke pupal diapause in H. armigera. The ED(50) of DH to terminate pupal diapause is 20 pmol/pupae. The other four FXPRLamide neuropeptides from the DH-PBAN polyprotein precursor have cross activity for diapause termination. These observations therefore suggest a potential role for these FXPRL family peptides in promoting continuous development in several noctuid species. The high expression of this gene in pharate adults and adults indicates that the FXPRL family peptides may have multiple physiological functions.