Peter Follette

Spatiotemporal regulation of Rho1 and Cdc42 activity during Candida albicans filamentous growth.

Rho G‐proteins are critical for polarized growth, yet little is known about the dynamics of their activation during fungal filamentous growth. We first investigated the roles of Rho1 and Rho2 during Candida albicans filamentous growth. Our results show that Rho1 is required for invasive filamentous growth and that Rho2 is not functionally redundant with Rho1. Using fluorescent reporters, we examined the dynamics of the active form of Rho1 and Cdc42 during initiation and maintenance of hyphal growth. Quantitative analyses indicated that the distribution, but not the level, of these active G‐proteins is altered during initial polarization upon germ tube emergence. A comparison of the dynamics of these active G‐proteins during budding and hyphal growth indicates that a higher concentration of active Cdc42 was recruited to the germ tube tip than to the bud tip. During hyphal elongation, active Cdc42 remained tightly restricted to the hyphal tip, whereas active Rho1 was broadly associated with the apex and subsequently recruited to the cell division site. Furthermore, our data suggest that phosphoinositide‐bis‐phosphates are critical to stabilize active Rho1 at the growth site. Together, our results point towards different regulation of Cdc42 and Rho1 activity during initiation and maintenance of filamentous growth.

Chemotropism During Yeast Mating

Virtually all eukaryotic cells can grow in a polarized fashion in response to external signals. Cells can respond to gradients of chemoattractants or chemorepellents by directional growth, a process referred to as chemotropism. The budding yeast Saccharomyces cerevisiae undergoes chemotropic growth during mating, in which two haploid cells of opposite mating type grow toward one another. We have shown that mating pheromone gradients are essential for efficient mating in yeast and have examined the chemotropism defects of different yeast mutants. Two methods of assessing the ability of yeast strains to respond to pheromone gradients are presented here.

Morphogenesis in Candida albicans: How to Stay Focused

Morphogenesis, such as the transition from budding to filamentous growth in Candida albicans, is a fundamental process that is of general interest both because of its cell biology and for its implication in host–pathogen interactions. Condition-specific transcriptome analyses and large-scale gene deletion or inactivation studies, together with forward and reverse genetic approaches, have uncovered a number of components involved in the regulation of the cellular reorganization that takes place in C. albicans during morphogenesis. This chapter will summarize the main components involved in cellular morphogenesis and provide an update of our knowledge of the regulatory steps that control the initiation and maintenance of polarized growth during C. albicans hyphal formation.

Bringing Biology Back to Croatia

MIROSLAV RADMAN PROFILEPARIS-- Biologist Miroslav Radman dreamed of returning to his native Croatia to build a world-class life sciences institute. Then someone gave him a villa to put it in.

Revolution or evolution for French science

There may be little love lost at the moment between the U.S. and French governments, but controversial changes under way at INSERM, France9s premier biomedical agency, strike many as the first steps toward an American-styled system.