Functional characterization and immunolocalization of odorant binding protein 1 in the lucerne plant bug, Adelphocoris lineolatus (GOEZE).

In the insect phylum, the relationships between individuals and their environment are often modulated by chemical communication. Odorant binding proteins (OBPs) are widely and robustly expressed in insect olfactory organs and play a key role in chemosensing and transporting hydrophobic odorants across the sensillum lymph to the olfactory receptor neuron. In this study, a novel OBP gene (AlinOBP1) in the lucerne plant bug, Adelphocoris lineolatus was identified, cloned and expressed. Real-time PCR results indicated that the expression level of AlinOBP1 gene differed in each developmental stage (from first instar to adult) and was predominantly expressed in the antennae of adults. The expression level of AlinOBP1 was 1.91 times higher in male antennae than in female antennae. The binding properties of AlinOBP1 with 114 odorants were measured using a fluorescence probe, N-phenyl-1-naphthylamine (1-NPN), with fluorescence competitive binding. The results revealed that AlinOBP1 exhibits high binding abilities with two major putative pheromone components, ethyl butyrate and trans-2-hexenyl butyrate. In addition, it was observed that six volatiles released from cotton, octanal, nonanal, decanal, 2-ethyl-1-hexanol, ß-caryophyllene and ß-ionone also bind to AlinOBP1. Immunocytochemistry analysis showed that AlinOBP1 was expressed in the sensillum lymph of sensilla trichodica and sensilla basiconca. Our results demonstrate that AlinOBP1 may function as a carrier in the chemoperception of the lucerne plant bug.

Binding specificity of locust odorant binding protein and its key binding site for initial recognition of alcohols.

Odorant binding proteins (OBPs) are required for olfaction perception, and thus may be possible targets for controlling the population of pests by interfering with their chemical communication. A single OBP LmigOBP1 has been identified in the antennae of Locusta migratoria, though four isoforms have been detected. Here, we have investigated the ligand-binding specificity of LmigOBP1 using 67 volatile odor compounds. Fluorescence assays indicate that LmigOBP1 does not bind fecal volatiles or green leaf odors, but shows high affinity for some linear aliphatic compounds, with pentadecanol and 2-pentadecanone being the strongest binding ligands. A 3-dimensional (3D) model of LmigOBP1 was built by homology modeling. Docking simulations based on this model suggested that Asn74 of LmigOBP1 is a key binding site, and this was validated by site-directed mutagenesis and fluorescence assays. We suggest that, as a general rule, a hydrophilic amino acid at the entrance of the binding cavity participates in initial recognition of ligands, and contributes to ligand-binding specificity of OBPs.

A new class of anti-thrombosis hexahydropyrazino-[1',2':1,6]pyrido-[3,4-b]-indole-1,4-dions: design, synthesis, logK determination, and QSAR analysis.

Based on the fact that the cyclization of N-[(3S)]-1,2,3,4-tetrahydro-beta-carboline-3-carboxyl]-l-lysine in both of acetic acid aqueous (5%) and rat plasma gave the same product and the hypothesis that the cyclization product is antithrombotic active, we report the synthesis, in vitro anti-aggregation, and in vivo anti-thrombosis activity of 20 hexahydropyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dions (5a-t) as potential anti-thrombosis agents in this study. Two intermediates (tetrahydro-beta-carboline-3-carboxy-l-amino acid benzylesters, 2-aminoacyltetrahydro-beta-carboline-3-carboxylic acid benzylesters) were prepared and used for the cyclization to form 5a-t. Coupling hydrochloric acid salt of tetrahydro-beta-carboline-3-carboxylic acid esters and Boc-amino acids in the reported literature usually generates very low yield products accompanied by racemization. However, in our case, the free base of tetrahydro-beta-carboline-3-carboxylic acid benzylester produced the desired products in high yields and without racemization. The anti-thrombosis results from both in vitro and in vivo studies revealed that 5a-t may be a new class of anti-thrombosis agents with potent effective concentration at 0.5mumol/kg with oral administration. Moreover, a QSAR analysis was performed on these 20 compounds by using molecular descriptors generated by e-dragon server. Although the activities of these compounds are weakly correlated with the logP values, the current QSAR analysis revealed that the anti-thrombotic activity of these compounds can be explained by their steric and electrostatic effects.