Résumé
In the yeast Xanthophyllomyces dendrorhous the genes idi, crtE, crtYB, crtl and ast are involved in the biosynthesis of astaxanthin from isopentenyl pyrophosphate. The carotenoid production and the kinetics of mRNA expression of structural genes controlling the carotenogenesis in a wild-type ATCC 24230 and in carotenoid overproducer deregulated atxS2 strains were studied. The biosynthesis of carotenoid was induced at the late exponential growth phase in both strains. However, the cellular carotenoid concentration was four times higher in atxS2 than in the wild-type strain in the exponential growth phase, suggesting that carotenogenesis was deregulated in atxS2 at the beginning of growth. In addition, the maximum expression of the carotenogenesis genes at the mRNA level was observed during the induction period of carotenoid biosynthesis in the wild-type strain. The mRNA level of the crtYB, crtl, ast genes and to a lesser extent the idi gene, decayed at the end of the exponential growth phase. The mRNA levels of the crtE gene remained high along the whole growth curve of the yeast. In the atxS2 strain the mRNA levels of crtE gene were about two times higher than the wild-type strain in the early phase of the growth cycle.
Sujets)
Basidiomycota/génétique , Caroténoïdes/génétique , Régulation de l'expression des gènes fongiques , Basidiomycota/métabolisme , Milieux de culture , Caroténoïdes/biosynthèse , RT-PCR , ARN fongique/génétique , ARN messager/génétique , XanthophyllesRésumé
La presentacion esta basada en 35 casos de quiste hidatico diagnosticados y corroborados quirurgicamente, que se estudiaron durante un periodo de 18 meses en el Centro de Tomografia Computada del Sanatorio Larghero.El quiste hidatico no complicado (hepatico o pulmonar) se presenta como una imagen hipodensa (0 a 10 uH) homogenea, de forma redondeada y limites netos. Las complicaciones vistas incluyen: 1) Infeccion que se traduce en un aumento de la densidad intraquistica en algunos casos aparicion de tabiques e irregularidad del contorno. En el pulmon se ven los fenomenos inflamatorios del parenquima circundante.2) Vesiculizacion, aparicion de vesiculas hijas y contorno polilobulados.3) Multiplicidad 4) Hidatidosis secundaria intraperitoneal. 5) Transito hepato-bronquico. 6) Hidatidosis pleural. En todos los casos se determino exatamente la cantidad de lesiones, el tamano y topografia de cada una de ellas