No abstract

The essential fungal cell-wall polymer (1,3)beta-glucan is synthesized by the enzyme (1,3)beta-glucan synthase. This enzyme, which is the target of the echinocandin and pneumocandin families of fungicidal antibiotics, is a complex composed of at least two proteins, Rho1p and Fks1p. Homologs of the yeast FKS1 gene have been discovered in numerous fungi, and existing evidence points to, but has not yet proved, Fks1p being the catalytic subunit of (1,3)beta-glucan synthase. We have purified (1,3)beta-glucan synthase from Neurospora crassa approximately 400-fold enrichment and labeled the substrate-binding protein by using a UDP-glucose analog, 5-azido-[beta-(32)P]-UDP-glucose. UDP-glucose-binding proteins were photo-crosslinked to the substrate analog and identified from SDS-PAGE gels by Quadrupole time-of-flight mass spectrometry by sequencing the tryptic peptides. Two plasma membrane proteins were labeled FKS and H(+)-ATPase. These results suggest that FKS appears to be the substrate-binding subunit of (1,3)beta-glucan synthase.

CAY-1, a novel saponin from Capsicum frutescens (commercially known as cayenne pepper) was investigated to determine its in vitro antifungal activity, mechanism of action and mammalian cell cytotoxicity. CAY-1 was active against 16 different fungal strains, including Candida spp. and Aspergillus fumigatus [minimum inhibitory concentrations (MIC) ranging from 4 to 16 microg ml(-1)], and was especially active against Cryptococcus neoformans (90% inhibition at 1 microg ml(-1)). Synergistic activity was also observed between CAY-1 and amphotericin B against Candida albicans and A. fumigatus. No significant cytotoxicity was demonstrated when CAY-1 was tested against 55 mammalian cell lines at up to 100 microg ml(-1). Importantly, CAY-1 appears to act by disrupting the membrane integrity of fungal cells.

No abstract

The Réunion harriers is an endemic raptor on Réunion Island. Several threats endanger its population, poisoning by rodenticides being considered as the main one currently. No information is available on its exposure to other chemicals notably trace metal elements such as lead (Pb), mercury (Hg), and cadmium (Cd). The Réunion harrier is still victim of poaching nowadays. When shooting is not lethal, animals may carry embedded shot in their body and thus be exposed to toxic level of Pb as demonstrated for other raptors. Moreover, recent monitoring suggests a decrease of its breeding success over time. It is known that Hg and Cd could impair reproduction and disturb embryo development in birds. The aim is to measure metal concentrations in the tissues of 30 carcasses of harrier collected from 2016 to 2021. Lead was analysed in liver and humerus while Hg and Cd were measured in livers. Concentrations were compared to toxicological reference values. Overall, the Reunion harrier was not exposed to toxic levels of Pb or Cd. For Hg, 53% of the individuals have residues higher than the threshold compatible with oxidative stress, 13% having liver concentrations above those compatible with reproduction impairment. A positive correlation was found between the proportion of urban area within 55 km² around a harrier and Hg concentration in liver. We conclude that Hg exposure could be a threat for the Réunion harrier population and recommend monitoring the exposure of the most sensitive stages, i.e., embryos and nestlings, to this metal with non-invasive methods.