Developmental regulation of the pheromone biosynthesis activating neuropeptide-receptor (PBAN-R): re-evaluating the role of juvenile hormone.

Sex pheromone production in Helicoverpa armigera is regulated by pheromone-biosynthesis-activating neuropeptide (PBAN), which binds to a G-protein coupled receptor at the pheromone gland. We demonstrate the temporal differential expression levels of the PBAN receptor (PBAN-R) gene, reaching peak levels at a critical period of 5 h post-eclosion. Previous studies implied a possible regulatory role for juvenile hormone (JH). We herein demonstrate that PBAN-R expression levels increase normally when females are decapitated or head-ligated, removing the source of JH, before peak transcript levels are reached. Similarly, sex pheromone production can be induced by PBAN in such decapitated females. These results indicate that up-regulation, at this critical time, is not dependent on JH originating from the head. Conversely, JH injected in vivo at this critical period significantly inhibits PBAN-R transcript levels.

Space flight alters bacterial gene expression and virulence and reveals a role for global regulator Hfq.

A comprehensive analysis of both the molecular genetic and phenotypic responses of any organism to the space flight environment has never been accomplished because of significant technological and logistical hurdles. Moreover, the effects of space flight on microbial pathogenicity and associated infectious disease risks have not been studied. The bacterial pathogen Salmonella typhimurium was grown aboard Space Shuttle mission STS-115 and compared with identical ground control cultures. Global microarray and proteomic analyses revealed that 167 transcripts and 73 proteins changed expression with the conserved RNA-binding protein Hfq identified as a likely global regulator involved in the response to this environment. Hfq involvement was confirmed with a ground-based microgravity culture model. Space flight samples exhibited enhanced virulence in a murine infection model and extracellular matrix accumulation consistent with a biofilm. Strategies to target Hfq and related regulators could potentially decrease infectious disease risks during space flight missions and provide novel therapeutic options on Earth.

Spatial distribution and differential expression of the PBAN receptor in tissues of adult Helicoverpa spp. (Lepidoptera: Noctuidae).

Pheromone-biosynthesis-activating neuropeptide (PBAN) regulates sex pheromone production in many female moths. PBAN-like peptides, with common FXPRLamide C-terminals are found in other insect groups where they have other functions. The ubiquity and multifunctional nature of the pyrokinin/PBAN family of peptides suggests that the PBAN receptor proteins could also be present in a variety of insect tissues with alternative functions from that of sex pheromone biosynthesis. Previously we showed the presence of the PBAN-R in Helicoverpa armigera at the protein level. In the present study we confirm the similarities between the two Helicoverpa species: armigera and zea by (1) demonstrating the presence of the receptor protein in Sf9 cells, cloned to express the HezPBAN receptor, as compared with the endogenous receptor protein, previously shown in H. armigera pheromone glands, and (2) by identifying the nucleotide sequence of the PBAN-R from mRNA of H. armigera pheromone glands. Sequences of the two Helicoverpa spp. are 98% identical with most changes taking place in the 3'-end. We demonstrate the spatial distribution of the PBAN receptor protein in membranes of H. armigera brain (Br), thoracic ganglion (TG) and ventral nerve cord (VNC). We also demonstrate the presence and differential expression of the PBAN receptor gene (using reverse transcription-polymerase chain reaction and reverse transcription-quantitative real-time polymerase chain reaction, respectively) in the neural tissues (Br, TG and VNC) of adult H. armigera female moths as compared with its presence in pheromone glands. Surprisingly, the gene for the PBAN receptor is also detected in the male tissue homologous to the female pheromone gland, the aedeagus, although the protein is undetectable and PBAN does not induce physiological (pheromone production) or cellular (cyclic-adenosine monophosphate production) responses in this tissue. Our findings indicate that PBAN or PBAN-like receptors are present in the neural tissues and may represent a neurotransmitter-like function for PBAN-like peptides. In addition, the surprising discovery of the presence of the gene encoding the PBAN receptor in the male homologous tissue, but its absence at the protein level, launches opportunities for studying molecular regulation pathways and the evolution of these G protein coupled receptors (GPCRs).

The effect of the juvenile hormone analog, fenoxycarb on the PBAN-receptor and pheromone production in adults of the moth Helicoverpa armigera: an "aging" hormone in adult females?

In a previous study we showed that juvenile hormone (JH) or its analog, fenoxycarb (FX), is involved in the up-regulation of pheromone biosynthesis-activating neuropeptide (PBAN) competence. JH causes induction of binding to a putative PBAN-receptor (PBAN-R) and the subsequent pheromone production by pheromone glands of pharate females. The present study demonstrates that pheromone production by the adult female is age-dependent. The pheromonotropic response increased to reach a maximum at 4 days, after which a decreased response was observed. Binding of the PBAN-R was also age-dependent. Treatment with FX inhibited both binding of PBAN to the PBAN-R and the pheromonotropic response as reflected by the production of the main pheromone component, Z-11-hexadecenal. Thus, in contrast to its up-regulatory role in pharate females, FX treatment of adult females causes down-regulation of both pheromone production and specific binding to the PBAN-R. In addition, behavioural observations showed that calling behaviour, mating success and subsequent egg-fertility are affected by treating females with FX.