4b, arrowheads). It is possible that such vesicles could be cytoplasmic debris that got trapped, as described previously (Bowers & Korn, 1969),
or secreted vesicles associated with the formation of the cyst wall such as the autophagosomes described previously in Acanthamoeba healyi encystment (Moon et al., 2009). Metal replicas showed that the ostiole appeared to be formed by the outermost part of the exocyst, with a modest or an absent intercyst space (Fig. 4d). The use of QF-DE revealed a novel picture of cyst wall organization in Acanthamoeba, showing that filamentous molecules dispersed in the buy AZD2281 intercyst space connecting the endocyst to the exocyst. A gradient of molecules is easily observed, with the denser cortex of the endocyst closer to the amoebae cell surface, which then assumes a more loosened appearance at the intercyst space. It is reasonable to postulate a pivotal role for this compact structure in conferring to Acanthamoeba cysts their peculiar resistance to diverse harsh conditions, including a high concentration of soluble biocides (Aksozek et al., 2002). The authors thank David Mercati for valuable technical help during the project and Prof.
Francine Marciano-Cabral for critically reading this manuscript. The Brazilian agencies CNPq and FAPERJ supported this work. “
“The ability of Bifidobacterium longum to use intestinal mucus as a metabolizable source was characterized. Bifidobacterium longum biotype longum NCIMB8809 was grown in a chemically semi-defined medium supplemented with human Etoposide chemical structure intestinal mucus, and the cytoplasmic protein profiles and several glycosyl hydrolase activities
were analysed and compared with those obtained from the same bacterium grown in the absence of mucus. We were able to identify 22 different proteins in the cytoplasmic fraction, of which nine displayed a different concentration in the presence of mucus. Among the proteins whose concentrations varied, we found specific enzymes that are involved in the response to different environmental conditions, and also proteins that mediate interaction Casein kinase 1 with mucus in bacteria. Significant changes in some glycoside-hydrolysing activities were also detected. In addition, stable isotope labelling of amino acids in cell culture demonstrated that B. longum incorporates leucine from the glycoprotein matrix of mucin within its proteins. This study provides the first proteomic data regarding the interaction of B. longum with intestinal mucus, and contributes to the understanding of the behaviour of this intestinal species in its natural ecological niche. Microorganisms of the genus Bifidobacterium are common inhabitants of the human gastrointestinal tract, constituting one of the predominant microorganisms in the colon during the early stages of life (Harmsen et al., 2000; Lay et al., 2005).