The suspensions were then spun down in an Eppendorf centrifuge, and the radioactivity in the supernatant measured in a liquid scintillation counter (Wallac, Model 1409). OptiPhase HiSafe 3 (PerkinElmer) was used as a liquid scintillation cocktail. All chemicals were of analytical grade, and, except where noted otherwise, were purchased from Sigma-Aldrich Kft., Budapest, Hungary. All the results presented here are means of 3–5 independent experiments. The data were analysed and visualized by Sigmaplot (Jandel Scientific), and standard deviations (SDs) for each procedure were Olaparib manufacturer determined.

The SD values were always < 14% of the means. Conidiospores of A. niger were unable to germinate in submerged minimal medium with 1% d-galactose as a sole carbon source even after a prolonged incubation. Essentially similar results were obtained on solid medium. However, mycelia of A. niger pregrown on glycerol (or on any other carbon source tested such as d-glucose, peptone, l-arabinose, d-xylose) and transferred to fresh medium containing d-galactose as a sole carbon source were able to grow, although at a rate lower than other fungi such as A. nidulans (Fekete et al., 2004) or T. reesei (Seiboth et al., 2004) (Fig. 1). The above results suggested that A. niger can AZD1152-HQPA datasheet grow on d-galactose once the spores have germinated but its conidiospores fail to

do so. This suggested to us that transport of d-galactose into Ferroptosis inhibitor the conidia may be nonfunctional. To investigate this hypothesis in more detail, we incubated mycelia and conidiospores,

respectively, with 14C-labelled d-galactose, and followed its uptake into the cells. Uptake by mycelia was related to dry weight. As it was practically impossible to determine biomass data for conidiospores in a reproducible way, we could not specify 14C-labelled d-galactose uptake on the same basis in these two sets of experiments. Instead, we employed three different concentrations of conidia, namely 106, 107 and 109 spores mL−1, respectively, under identical experimental conditions. Any d-galactose uptake was therefore expected to be proportional to the number of conidiospores present in the medium. Data obtained indeed showed that the mycelia preformed on glycerol were able to transport d-galactose (Fig. 2a). On the other hand, there was no 14C-labelled d-galactose uptake by the conidiospores irrespective of their concentration (Fig. 2b), indicating the absence of d-galactose transport at this stage of growth in A. niger. The d-galactose-negative phenotype of A. niger was earlier speculated to be the consequence of a lack of galactokinase activity (Elshafei & Abdel-Fatah, 2001). In contrast, cell-free extracts of A. niger mycelia prepared by us were able to phosphorylate d-galactose, resulting in a specific galactokinase activity similar in value to that of A. nidulans (Ilyés et al., 2004).