, 2008). Although apoptotic processes have been described in a number of yeasts and filamentous fungi, zygomycetes have remained poorly characterized in this respect. There has only been one report on the apoptosis-like cell death process in zygomycetes (Roze & Linz, 1998), where the apoptotic process was triggered by the HMG-CoA reductase inhibitor, lovastatin, in Mucor racemosus. The described changes in the sporangiospore germination and hyphae formation were similar to those observed in our experiments. In that study, DNA fragmentation, with
laddering, associated with the apoptosis-like process was also observed. This feature could be detected only when the treated cells were incubated at pH 7.45; the usual incubation pH (generally at pH 4.5) prevented the activation of the DNA fragmentation response. In our experiments, DNA laddering ABT-737 concentration was detected neither at pH 4.5 nor at pH 7.45 (result
not shown). However, it is worth mentioning that DNA laddering associated with PCD has rarely been observed in fungi and that this phenomenon is CX-5461 mw also not an absolute feature of apoptosis in mammalian cells (Ramsdale, 2006). Currently, further experiments are in progress to elucidate the molecular background of the antifungal effect of ophiobolins and their possible interaction with fungal calmodulins. Our results suggest that these compounds may offer a promising tool to examine the death-related signaling pathways in fungi. This work was supported by a grant from the Hungarian Scientific Research Fund and the National Office for Research and Technology (CK 80188). “
“Department of Microbiology and Immunology, Dartmouth Medical School, Lebanon, NH, USA Thurston Arthritis Research Center at UNC Chapel Hill, Chapel Hill, NC, USA Biofilm formation in Vibrio cholerae is in part regulated by norspermidine, a polyamine synthesized by the enzyme carboxynorspermidine decarboxylase (NspC). The absence of norspermidine in the cell leads to a marked Phospholipase D1 reduction in V. cholerae biofilm formation by an unknown mechanism. In this work, we show that overexpression of nspC results
in large increases in biofilm formation and vps gene expression as well as a significant decrease in motility. Interestingly, increased NspC levels do not lead to increased concentrations of norspermidine in the cell. Our results show that NspC levels inversely regulate biofilm and motility and implicate the presence of an effective feedback mechanism maintaining norspermidine homeostasis in V. cholerae. Moreover, we provide evidence that NspC and the norspermidine sensor protein, NspS, provide independent and distinct inputs into the biofilm regulatory network. Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, is a natural inhabitant of aquatic environments, where it is believed to exist predominantly in biofilms (Colwell & Huq, 1994; Colwell et al., 2003).