RESUMEN
Many cyanobacteria exhibit surface motility powered by type 4 pili (T4P). In the model filamentous cyanobacterium Nostoc punctiforme, the T4P systems are arrayed in static, bipolar rings in each cell. The chemotaxis-like Hmp system is essential for motility and the coordinated polar accumulation of PilA on cells in motile filaments, while the Ptx system controls positive phototaxis. Using transposon mutagenesis, a gene, designated hmpF, was identified as involved in motility. Synteny among filamentous cyanobacteria and the similar expression patterns for hmpF and hmpD imply that HmpF is part of the Hmp system. Deletion of hmpF produced a phenotype distinct from other hmp genes, but indistinguishable from pilB or pilQ. Both an HmpF-GFPuv fusion protein, and PilA, as assessed by in situ immunofluorescence, displayed coordinated, unipolar localization at the leading pole of each cell. Reversals were modulated by changes in light intensity and preceded by the migration of HmpF-GFPuv to the lagging cell poles. These results are consistent with a model where direct interaction between HmpF and the T4P system activates pilus extension, the Hmp system facilitates coordinated polarity of HmpF to establish motility, and the Ptx system modulates HmpF localization to initiate reversals in response to changes in light intensity.
Asunto(s)
Nostoc/genética , Proteínas Bacterianas/metabolismo , Movimiento Celular , Quimiotaxis/fisiología , Fimbrias Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica/genética , Locomoción , Nostoc/metabolismoRESUMEN
Se realizó estudio retrospectivo en 07 pacientes sometidos a pancreaticoduodenectomia entre los años 1981-1986; 02 tuvieron anastomosis pancreaticoyeyunal; 05 ligaduras del conducto de Wirsung, éstos últimos presentaron fistula pancreática en el postoperatorio inmediato; en 04 la fístula cerró espontáneamente en 4-5 semanas; sin embargo 01 falleció por sepsis a punto de partida intraabdominal. El 85% presentó complicaciones postoperatorias con una mortalidad operatoria del 14%. El seguimiento de nuestros pacientes fue adecuado; sólo 01 se perdió de vista; 02 que tuvieron ligadura del conducto de Wirsung fallecieron al año y 2 en caquexia extrema sin evidencia de recurrencia de enfermedad; 01 fallecio a los 3 meses por cuadro de colabgitis sepsis coma hepático