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The effects of long-term exposure (5 h) of Phycomyces blakesleeanus mycelium to 5 mM KCN on respiration and phosphate metabolites were tested. Exposure to cyanide, antimycin A and azide lead to a decrease in the activity of cyanide-sensitive respiration (CSR), and the ratio of core polyphosphates (PPc) and inorganic phosphates (Pi), which is a good indicator of the metabolic state of a cell. After 5 h of incubation, the activity of CSR returned to control values. For this, the recovery of cytochrome c oxidase (COX) was required. In addition, the PPc/Pi ratio started to recover shortly after initiation of COX recovery, but never reached control values. This led us to conclude that the regulation of polyphosphate (PPn) levels in the cell is tightly coupled to respiratory chain functioning. In addition, acutely applied cyanide caused two different responses, observed by 31P NMR spectroscopy, that were probably mediated through the mechanism of glycolytic oscillations, triggered by the effect of cyanide on mitochondria. [Projekat Ministarstva nauke Republike Srbije, br. 173040]

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The possibility of reduction of vanadate monomer in the mycelium of fungus Phycomyces blakesleeanus was investigated in this study by means of polarography. Control experiments were performed with vanadyl [V(IV)] and vanadate [V(V)] in 10 mM Hepes, pH 7.2. Addition of P. blakesleeanus mycelium resulted in disappearance of all V(IV) polarographic waves recorded in the control. This points to the uptake of all available V(IV) by the mycelium, up to 185 µmol/g, and suggests P. blakesleeanus as a potential agent in V(IV) bioremediation. Polarographic measurements of mycelium with low concentrations (0.1-1 mM) of V(V), that only allows the presence of monomer, showed that fungal mycelia removes around 27% of V(V) from the extracellular solution. Uptake was saturated at 104 ± 2 µmol/g which indicates excellent bioaccumulation capability of P. blakesleeanus. EPR, V NMR and polarographic experiments showed no indications of any measurable extracellular complexation of V(V) monomer with fungal exudates, reduction by the mycelium or adsorption to the cell wall. Therefore, in contrast to vanadium oligomers, vanadate monomer interactions with the mycelium are restricted to its transport into the fungal cell, probably by a phosphate transporter.

Abstract. Soil samples from Novi Pazar (Serbia) and Rožaje (Montenegro) were analyzed by the ORTEC HPGe detectors with relative efficiencies of 35 and 40 % for radioactivity of 226 Ra, 232 Th/ 228 Ac, 40 K and 137 Cs. An average radioisotope activity concentration for Novi Pazar soil was found to be 27.6, 49.5, 585 and 14.9 Bq/kg, respectively; while in Rožaje, 137 Cs activity concentration was found to be significantly higher -from 33.9 to 322 Bq/kg. The obtained results were used to estimate hazard indices, such as radium equivalent activity (none of the localities showed a radium equivalent activity higher than 370 Bq/kg) and annual gonadal dose equivalent to natural radioisotopes, as well as external terrestrial gamma absorbed dose rate of 226 Ra, 232 Th/ 228 Ac, 40 K and 137 Cs, and corresponding annual effective dose -used to evaluate excess lifetime cancer risk (then compared with the world average of 0.2⋅10 -3 , taking into account external terrestrial radiation -outdoor, i.e., average annual effective dose of 0.07 mSv). Vegetation samples from Rožaje -blackberry (Rubus fruticosus), spruce (Picea abies) and beech (Fagus sylvatica) showed 226 Ra activity -4.03, 1.1 and 0.99 Bq/kg, respectively; 232 Th/ 228 Ac -4.5, <1.22 and 2.89 Bq/kg, respectively; 40 K -152, 98.4 and 79.3 Bq/kg, respectively; 137 Cs -3.05, 3.54 and 5.24 Bq/kg, respectively; whilst in Pinus sylvestris from Novi Pazar, they were -2.7, 2.11, 163, <0.34 Bq/kg, respectively. Soil-plant radioisotope transfer factors were also estimated, and compared with typical ranges given in the UNSCEAR 2008 report. Since the most important radiation source for all terrestrial biota is the activity from soil, the dose rates are also evaluated using known internal (and external -in soil) radioisotope activity concentrations, as well as corresponding the dose conversion coefficients for external and internal exposure to particular radioisotope.