Liu Fengquan

Detection of a quorum sensing signal molecule of Acidovorax avenae subsp. citrulli and its regulation of pathogenicity.

An efficient AHL ( N -acyl-homoserine lactone) bioassay strain, JZA1, of Agrobacterium tumefaciens was used to detect the AHL production from Acidovorax avenae subsp. citrulli [the pathogen causing bacterial fruit blotch (BFB) of melons], and the results showed that A. avenae subsp. citrulli produced a 3-O-C 8 -homoserine (HSL) type signal molecule. Gene aiiA , which could degrade AHL molecules, was transformed into A. avenae subsp. citrulli strain NJF10, creating strain NJF10- aiiA . The AHL production from NJF10- aiiA was significantly reduced compared with wild-type NJF10. Inoculation tests showed that NJF10- aiiA had an obvious reduction of virulence on watermelon fruits. Our finds showed that AHL production by A. avenae subsp. citrulli was related to its pathogenicity. This work might provide a novel way to control BFB by QS (quorum sensing) interference.

Production and Characterization of Polyclonal Antibody for the N-Methylcarbamate Insecticide Metolcarb

Abstract The hapten, 3-{[1-(3-(methyl)phenyloxy)-carbonyl]amino}propanoic acid (HOM), mimicking the analyte metolcarb. was synthesized and verified by mass spectrometry (MS) and 1H-nuclear magnetic resonance spectrometry (1H-NMR). Then, HOM was conjugated with the carrier proteins bovine serum albumin (BSA) and ovalbumin (OVA) with stoichiometric amounts of N-hydroxysuccinimide/dicyclohexylcarbodimide (NHS/DCC) using the activated ester method. Polyclonal antibodies were raised against the conjugate of HOM-BSA in rabbits. Antiserum titres were determined by noncompetitive indirect ELISA procedures and the titer of pAb01 reached 1.28 × 106. The cross-reactivities of the structurally related N-methylcarbamate insecticides were 0.0% except for dimethacarb. These results indicate that the antibody pAb01 with strong affinity and high specificity can be used to develop a sensitive and rapid detection protocol for metolcarb residue.