No abstract

No abstract

In this study, a random mutant library of Herbaspirillum seropedicae SmR1 was constructed by Tn5 insertion and a mutant incapable of utilizing naringenin as a carbon source was isolated. The Tn5 transposon was found to be inserted in the fdeE gene (Hsero_1007), which encodes a monooxygenase. Two other mutant strains in fdeC (Hsero_1005) and fdeG (Hsero_1009) genes coding for a dioxygenase and a putative cyclase, respectively, were obtained by site-directed mutagenesis and then characterized. Liquid Chromatography coupled to mass spectrometry (LC-MS)/MS analyses of culture supernatant from the fdeE mutant strain revealed that naringenin remained unaltered, suggesting that the FdeE protein is involved in the initial step of naringenin degradation. LC-MS/MS analyses of culture supernatants from the wild-type (SmR1) and FdeC deficient mutant suggested that in H. seropedicae SmR1 naringenin is first mono-oxygenated by the FdeE protein, to produce 5,7,8-trihydroxy-2-(4-hydroxyphenyl)-2,3-dihydro-4H-chromen-4-one, that is subsequently dioxygenated and cleaved at the A-ring by the FdeC dioxygenase, since the latter compound accumulated in the fdeC strain. After meta-cleavage of the A-ring, the subsequent metabolic steps generate oxaloacetic acid that is metabolized via the tricarboxylic acid cycle. This bacterium can also modify naringenin by attaching a glycosyl group to the B-ring or a methoxy group to the A-ring, leading to the generation of dead-end products.

Os compostos utilizados pelo percevejo da soja Piezodorus guildinii como feromônio de alarme foram caracterizados através da análise da composição química das secreções da glândula metatorácica dos insetos adultos. Além dos hidrocarbonetos característicos, (E)-2-hexenal e (E)-4-oxo-2-hexenal foram detectados como constituintes majoritários. Tais compostos já foram previamente descritos como feromônio de alarme em outras espécies de pentatomídeos.The compounds utilized by the soybean stink bug Piezodorus guildinii as alarm pheromone were characterized by analysis of the chemical composition of the metathoracic scent gland secretions from adult bugs. In addition to characteristic hydrocarbons, (E)-2-hexenal and (E)-4-oxo-2-hexenal were detected as major constituents. These compounds were previously described as alarm pheromone in several other pentatomid species.

A resposta comportamental de machos e fêmeas adultos de Pseudopiazurus obesus (Boheman, 1838) (Coleoptera: Curculionidae) a várias fontes de odores foi avaliada em um olfatômetro de tubo em Y. insetos machos e fêmeas foram significativamente mais atraídos para uma combinação dos voláteis emitidos pelos machos da espécie e pela planta hospedeira, sugerindo a existência de um feromônio de agregação produzido pelos machos. Análises comparativas dos voláteis emitidos pelos machos e fêmeas revelaram três compostos machoespecíficos, em uma relação de 77:14:9, dando suporte químico às observações comportamentais. (1R,2S)-(+)-Grandisal e (1R,2S)-(+)-grandisol foram identificados como sendo os compostos majoritário e intermediário, respectivamente, enquanto que a estrutura química do componente minoritário, que parece ser um novo derivado do grandisol, ainda necessita ser determinada. Estes três compostos são os principais candidatos a feromônio na espécie.The behavioral responses of adult male and female Pseudopiazurus obesus (Boheman, 1838) (Coleoptera: Curculionidae) to several odour sources were evaluated in a Y-tube olfactometer. Males and females insects were significantly more attracted to a combination of volatiles released by males of the species and host plant, suggesting the existence of a male-produced aggregation pheromone. Comparative analysis of the volatiles released by males and females revealed three male-specific compounds, in a ratio of 77:14:9, providing a chemical support to the behavioral observations. (1R,2S)-(+)-Grandisal and (1R,2S)-(+)-grandisol were identified as the major and intermediate compounds, respectively, while the chemical structure of the minor compound, that seems to be a new grandisol derivative, still remains to be determined. These three compounds are the most important pheromone candidates in the species.