[Show abstract][Hide abstract]ABSTRACT: Apoptosis is a highly regulated form of programmed cell death (PCD) crucial for life and health in Metazoa. Yeast have been used as a model eucaryotic organism to study apoptosis. Unexpectedly, several researchers observed a PCD process in yeast in response to heterologous expression of proapoptotic genes. Following that discovery, different factors inducing apoptosis in yeast cells were identified, e.g. H2O2, acetic acid, cellular ageing, failed mating. Further investigations revealed that several regulators of apoptosis are conserved between Metazoa and yeast. There are three natural conditions of yeast population i.e. environmental stress conditions, failure to mate, and aging in which PCD in yeast cells occurrs and seems to be beneficial for the whole population. Therefore, PCD might serve as an important regulator of yeast cell populations. However, the lack of homologs of crucial PCD regulators, such as Bcl-2 family proteins or unidentified genuine substrates for Yeast Caspase-1, make the existance of PCD mechanism in yeast disputable. The ability to manipulate fungi still presents exciting challenges. The manipulations of fungal PCD could provide a basis for future therapies.
[Show abstract][Hide abstract]ABSTRACT: The past years has witnessed a significant increase in the prevalence of resitance to antifungal agents. Understanding the mechanisms of action of different antifungal agents is an important prereguisite to understanding mechanisms of resistance. Thus mechanisms of resistance to individual antifungal classes are preceded by explanation of their antifungal activity in this article. Azoles, polyenes and allylamine, commonly used in clinical practise, all owe their antifungal activities to inhibition of synthesis of cell membrane or direct interaction of the fungal cell membrane. Echinocandins are specific inhibitors of fungal glucan synthase, and 5-fluorocytosine is inhibiting nucleic acids. There are several mechanisms by which fungal cells might develop resistance: the target enzyme is overproduced, the drug target is altered, the drug is pumped out by an efflux pump, the entry of the drug is prevented at the cell membrane, the cell has a bypass pathway that compensates for the loss of function due to the drug activity, fungal enzymes which convert an inactive drug to its active form are inhibited, and enzymes which degrade the drug are secreted by the fungal cell. The expression of resistance to antifungal agents is the inevitable consequence of using these agents to treat human infections. With increased use and availability of different classes of antifungal agents it is anticipated that we will see an increasing number and variety of fungal species resistant to these agents in the near future.
[Show abstract][Hide abstract]ABSTRACT: Cell surface hydrophobicity (CSH) is considered to be one of several virulence factors of Candida yeast-like fungi. The aim of the study was a measurment of hydrophobic properties of Candida sp. depending on growth conditions. A total of 139 strains of Candida (80 - C. albicans and 59 - C. non-albicans) were examined. The method of salt aggregation test (SAT) was used. The strains were cultured on three different media, in two variants of incubation temperature and time. The incubation temperature and microbiological medium affected CSH of just C. albicans strains. The influence of incubation time on CSH of examined species of Candida was not occurred. There was a strong correlation between CSH and species of Candida demonstrated in the study Hydrophobic properties were more frequent and stronger among strains of C. non-albicans than C. albicans species. The results of the study indicates that CSH of Candida spp. is a dynamic feature. The ability to change surface properties may play a role in pathogenesis of candidosis.
Article · Feb 2006 · Medycyna doświadczalna i mikrobiologia