[show abstract][hide abstract] ABSTRACT: To investigate the molecular scavenging capabilities of the larvae of Hermetia illucens, two serine proteases (SPs) were cloned and characterized. Multiple sequence alignments and phylogenetic tree analysis of the deduced amino acid sequences of Hi-SP1 and Hi-SP2 were suggested that Hi-SP1 may be a chymotrypsin- and Hi-SP2 may be a trypsin-like protease. Hi-SP1 and Hi-SP2 3-D homology models revealed that a catalytic triad, three disulfide bonds, and a substrate-binding pocket were highly conserved, as would be expected of a SP. E. coli expressed Hi-SP1 and Hi-SP2 showed chymotrypsin or trypsin activities, respectively. Hi-SP2 mRNAs were consistently expressed during larval development. In contrast, the expression of Hi-SP1 mRNA fluctuated between feeding and molting stages and disappeared at the pupal stages. These expression pattern differences suggest that Hi-SP1 may be a larval specific chymotrypsin-like protease involved with food digestion, while Hi-SP2 may be a trypsin-like protease with diverse functions at different stages.
[show abstract][hide abstract] ABSTRACT: We conducted experiments in Drosophila to investigate the consequences of altered acetylcholinesterase (AChE) activity in the nervous system. In ace hypomorphic mutant larvae, the amount of ace mRNA and the activity of AChE both in vivo and in vitro were significantly reduced compared with those of controls. Reduced Ace in Drosophila larvae resulted in significant down-regulation of branch length and the number of boutons in Type 1 glutamatergic neuromuscular junctions (NMJs). These defects in ace hypomorphic mutant larvae were suppressed when Musca domestica AChE was transgenically expressed. Because AChE inhibitors are utilized for medications for Alzheimer's disease, we investigated whether pharmacological inhibition of AChE activity induced any synaptic defects. We found that controls exposed to a sublethal dose of DDVP phenocopied the synaptic structural defects of the ace hypomorphic mutant. These results suggest that down-regulation of AChE activity, regardless of whether it is due to genetic or pharmacological manipulations, results in altered synaptic architecture. Our study suggests that exposure to AChE inhibitors for 6-12 months may induce altered synaptic architectures in human brains with Alzheimer's diseases, similar to those reported here. These changes may underlie or contribute to the loss of efficacy of AChE inhibitors after prolonged treatment.
Neurochemical Research 02/2011; 36(5):879-93. · 2.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: Organic memory devices based on CdSe nanoparticles (NPs) embedded in polymethylmethacrylate (PMMA) insulating layer are demonstrated. The use of NPs/polymer blend as a tunneling layer for non-volatile organic memory has proven to be an alternative route to manipulate and improve the device characteristics. The memory effect is adjustable upon changing the concentration of CdSe NPs within the PMMA tunneling insulator, and the tunable device performance is ascribed to the different trap densities in floating gate. The capacitance change is analyzed by monitoring the charge transport between pentacene and the CdSe NPs. Our in-depth study reveals that the increase in CdSe NPs leads to a wider memory window and better hysteresis characteristics with a maximum window of −8.6 V at VGS of −30 V for 1 s. This result demonstrates the potential application of organic/inorganic hybrid floating gate structure in organic memory devices.