ABSTRACT
The bacterium Herbaspirillum seropedicae is an endophytic diazotroph found in several plants, including economically important poaceous species. However, the mechanisms involved in the interaction between H. seropedicae and these plants are not completely characterized. We investigated the attachment of Herbaspirillum to maize roots and the invasion of the roots by this bacterium using H. seropedicae strain SMR1 transformed with the suicide plasmid pUTKandsRed, which carries a mini-Tn5 transposon containing the gene for the Discosoma red fluorescent protein (Dsred) constitutively expressed together with the kanamycin resistance gene. Integration of the mini-Tn5 into the bacterial chromosome yielded the mutant H. seropedicae strain RAM4 which was capable of expressing Dsred and could be observed on and inside fresh maize root samples. Confocal microscopy of maize roots inoculated with H. seropedicae three days after germination showed that H. seropedicae cell were attached to the root surface 30 min after inoculation, were visible in the internal tissues after twenty-four hours and in the endodermis, the central cylinder and xylem after three days.
Subject(s)
Herbaspirillum , Zea mays/genetics , Microscopy, Confocal , Nitrogen FixationABSTRACT
O grupo de trabalho em Diabetes e Gravidez, reunido durante o XI Congresso Brasileiro de Diabetes, em 1997, elaborou normas para o manejo do diabetes gestacional e pré-gestacional. O rastreamento do diabetes gestacional deve ser seletivo, isto é, dirigido a gestantes com fatores de risco. Para tanto é sugerido o emprego da glicemia de jejum a partir da 20ª semana de gestaçäo. Pontos de corte de 85mg/dl ou 90mg/dl sao sugeridos para classificaçäo de rastreamento positivo, que indica a necessidade de um teste oral de tolerância com 75g de glicose. Esse teste deve ser interpretado de acordo com os crit'erios sugeridos pela organizaçäo Mundial da Saúde (glicemia de jejum >/= 126mg/dl ou glicemia de 2h >/= 140mg/dl). Säo apresentadas também estratégias de manejo metabólico e obstétrico do diabetes gestacional e pré-gestacional.