Functional characterization of the Aspergillus fumigatus calcineurin.

TLDR: Results suggest that calcineurin is involved in the regulation of the PHO pathway in A. fumigatus and opens new venues for the research on sensing and nutrient acquisition in this fungus.

About: This article is published in Fungal Genetics and Biology.The article was published on 2007-03-01 and is currently open access. It has received 118 citations till now. The article focuses on the topics: Calcineurin & Aspergillus fumigatus.

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Table 1. List of primers used in this work for the real-time RT-PCRs

Table 3. Inhibition of the calcineurin decreases the inorganic phosphate transport in A. fumigatus

Table 4. Expression of putative transporter encoding genes when A. fumigatus is grown in the presence of tacrolimus

Figure 1. Calcineurin is required for colony extension: spores from each strain were inoculated in MM plates (plus supplements) and incubated at 37 °C overnight to produce a nonsporulating mycelial “mat.” Mycelial “plugs” were cut from the mats using the wide end of a sterile Pasteur pipette. The plugs were transferred onto MM plates and incubated for 3 days at 37 °C. (A) Colony morphology (upper panels) and growth rate of wild-type (diamond shape) and ΔcalA (square shape) colonies (lower left panel). The diameter of colonies was measured daily after the transfer of the mycelial plugs which were originally 1 cm in diameter. The average of three independent experiments is shown. Lower right panels are higher magnifi cation images showing the edge of the colonies represented in the plates of the upper panels. Wild-type, bar, 100 μm; ΔcalA, bar, 10 μm. (B) Calcineurin is required for proper hyphal branching. Conidia of wild-type and ΔcalA mutant strains were inoculated in liquid YG and incubated at 37 °C for 10 h (upper panels; wild-type, bar, 27 μm; ΔcalA, bar, 22 μm). Samples were fi xed and stained with DAPI and calcofl uor, then analyzed by light microscopy and the number of branches counted. (C) Calcineurin infl uences spore morphology. Wildtype spores display uniform morphology and size, whereas ΔcalA spores (B) exhibit abnormal size (represented by arrows) or “tear-shape” morphology (represented by double arrows). Bars, 5 μm. Those abnormal spores have no nucleus.

Table 2. Calcineurin inhibition does not affect the acid phosphatase activity a, b

Figure 5. Aspergillus fumigatus ΔcalA mutant cannot grow in fetal bovine serum without supplemented phosphate. (A) The wildtype and ΔcalA mutant strains were point inoculated either in MM and grown for 48 h at 37 °C (fi rst row), or 10% FBS, 10% FBS + TE (trace elements according to Kafer, 1977), and 10% FBS + SS (salts solution according to Kafer, 1977) (second row), or 10% FBS + NaNO3, 10% FBS + KCL, 10% FBS + KH2PO4, 10% FBS + MgSO4 (third row) and grown for 72 h at 37 °C. (B) Conidia from the wild-type and ΔcalA mutant strains were inoculated in 10% FBS and FBS + KH2PO4 solid media and grown for 48 h at 37 °C. Bar, 33 μm. In both experiments in solid and liquid medium, the plates and tubes were incubated up to 10 days a 37 °C and no growth was observed in the ΔcalA mutant.