Invertebrate Trehalose-6-Phosphate Synthase Gene: Genetic Architecture, Biochemistry, Physiological Function, and Potential Applications.

The non-reducing disaccharide trehalose is widely distributed among various organisms. It plays a crucial role as an instant source of energy, being the major blood sugar in insects. In addition, it helps countering abiotic stresses. Trehalose synthesis in insects and other invertebrates is thought to occur via the trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) pathways. In many insects, the TPP gene has not been identified, whereas multiple TPS genes that encode proteins harboring TPS/OtsA and TPP/OtsB conserved domains have been found and cloned in the same species. The function of the TPS gene in insects and other invertebrates has not been reviewed in depth, and the available information is quite fragmented. The present review discusses the current understanding of the trehalose synthesis pathway, TPS genetic architecture, biochemistry, physiological function, and potential sensitivity to insecticides. We note the variability in the number of TPS genes in different invertebrate species, consider whether trehalose synthesis may rely only on the TPS gene, and discuss the results of in vitro TPS overexpression experiment. Tissue expression profile and developmental characteristics of the TPS gene indicate that it is important in energy production, growth and development, metamorphosis, stress recovery, chitin synthesis, insect flight, and other biological processes. We highlight the molecular and biochemical properties of insect TPS that make it a suitable target of potential pest control inhibitors. The application of trehalose synthesis inhibitors is a promising direction in insect pest control because vertebrates do not synthesize trehalose; therefore, TPS inhibitors would be relatively safe for humans and higher animals, making them ideal insecticidal agents without off-target effects.

Spatial and temporal expression of N-ethylmaleimide-sensitive factor gene in the nervous system of the cotton bollworm, Helicoverpa armigera.

N-ethylmaleimide-sensitive factor (NSF) is a component required for vesicular transport and release of neurotransmitters or neurohormones in the constitutive secretory pathways. Here, the spatial and temporal expression of NSF gene was investigated in Helicoverpa armigera (Helar). Reverse transcription-polymerase chain reaction analysis reveals that Helar-NSF is transcribed preferentially in the nervous system of H. armigera. Using in situ hybridization, the Helar-NSF mRNA is further localized in the superficial layer or deep layer cells of the brain, subesophageal ganglion (SG) and other ganglia. The developmental profiles of Helar-NSF show that both mRNA and protein in pupal brain-SG complexes are significantly higher in nondiapause-destined individuals than in diapause-destined individuals. The expression patterns are consistent with those of two neurohormones, prothoracicotropic hormone (PTTH) and diapause hormone (DH). These data suggest a central function of Helar-NSF in developmental process through regulating neurohormone release.

Molecular characterization and functional distribution of N-ethylmaleimide-sensitive factor in Helicoverpa armigera.

N-ethylmaleimide-sensitive fusion protein (NSF) is an essential component for the neurotransmitter or neurohormone release apparatus present in all eukaryotic cells. Here, a new NSF orthologue was characterized from the cotton bollworm, Helicoverpa armigera (Har). Northern blot exhibited a high expression in larval brain. Southern analysis indicated that a single copy of the gene is present in a haploid genome. Using antibodies labeled with fluoresceins, we directly proved that NSF is co-localized with two crucial neurohormones, prothoracicotropic hormone and diapause hormone, both of which regulate insect development. These findings suggest that Har-NSF may be involved in regulating insect neurohormone release.