Probing the effect of tip pressure on fungal growth: Application toAspergillus nidulans

Abstract

The study of fungal cells is of great interest due to their importance as pathogens and as fermenting fungi and for their appropriateness as model organisms. The differential pressure between the hyphal cytoplasm and the bordering medium is essential for the growth process, because the pressure is correlated with the growth rate. Notably, during the invasion of tissues, the external pressure at the tip of the hypha may be different from the pressure in the surrounding medium. We report the use of a method, based on the micropipette-aspiration technique, to study the influence of this external pressure at the hyphal tip. Moreover, this technique makes it possible to study hyphal growth mechanics in the case of very thin hyphae, not accessible to turgor pressure probes. We found a correlation between the local pressure at the tip and the growth rate for the species Arpergillus nidulans. Importantly, the proposed method allows one to measure the pressure at the tip required to arrest the hyphal growth. Determining that pressure could be useful to develop new medical treatments for fungal infections. Finally, we provide a mechanical model for these experiments, taking into account the cytoplasm flow and the wall deformation.

Advances in Micropipette Aspiration: Applications in Cell Biomechanics, Models, and Extended Studies

“…Recently, micropipette aspiration has been used to study fungal cells, characterized by a cell wall resisting a great turgor pressure. We developed a procedure to study the influence of the differential pressure applied at the tip, DP, on the growth rate dL p /dt (59), predicting and measuring a DP value that arrests the cell growth.…”

External signal–mediated polarized growth in fungi

“…Primary examples of fungal external signal-mediated polarized growth are mating projection formation in Saccharomyces cerevisiae and Schizosaccharomyces pombe, and hyphal cells in filamentous and dimorphic fungi, including Neurospora crassa, Aspergillus nidulans and Candida albicans (Figure 1). In fungi, polarized growth occurs in the presence of an internal hydrostatic pressure (turgor), which is on the order of 0.5 -1.5 MPa for the aforementioned species, that is 0.1 mg/µm 2 [1][2][3][4][5][6][7][8]. In each of these fungi, an initial asymmetry is triggered in response to an external signal.…”

Deformability of T cells as a mechanical biomarker of immunosenescence and development of techniques for the clinical application

“…Materials and methodsThis chapter describes and justifies the experimental protocols and methods used for data acquisition, analysis and modeling. The contents of sections 4.1.2 and 4.1.3 are included in two published articles, which are part of this doctoral work 315,316. 4.1 Cells4.1.1 T cellsMiceNine ICR-CD1, Mus musculus, female mice were used for the longitudinal study, purchased from Janvier S.A.S., Le Genest-St-Isle, France.…”