Growth and morphogenesis ofBotrytis cinerea. Effects of exogenous calcium ions,calcium channel blockers and cyclosporin A

Calcium channel blockers, verapamil, nitrendipin and nifedipin, and cyclosporin A inhibited growth of colonies ofBotrytis cinerea in a concentration-dependent manner and simultaneously induced morphological changes of its hyphal tips. Exogenous calcium at the concentration of 100 mmol/L decreased the growth-inhibitory effects of channel blockers and cyclosporin A; however, at the concentration of 500 mmol/L Ca²⁺ their inhibitory effects were increased. At the latter concentration, calcium partly reversed the morphogenic effects of the blockers but not of cyclosporin A.     

Regulation of periodicity and intensity of photo-induced conidiation ofTrichoderma viride

After a short irradiation at 366 nm with 200 lx, the intensity of conidiation ofTrichoderma viride colonies grown in the dark increased for the first 10 s proportionally with time. The increase slowed down after 10 s—6 min of exposure and after 10–60 min of irradiation the conidiation intensity began to decrease. When photo-induced by daylight, the conidiation started at a high rate after 25 h and persisted even after 48 h. The conidiation had no circadian character and its periodicity depended on the periodicity of photo-induction. Its intensity was also influenced by the carbon sources used, a maximum being reached with glucose (1–2 %). Higher glucose concentrations inhibited conidiation but had no influence on growth of colonies.     

Effects of agents affecting Ca2+ homeostasis onTrichoderma viride growth and conidiation

Agents known to influence Ca²⁺ homeostasis affected significantly the vegetative growth and starvation-induced conidiation ofTrichoderma viride. Ca²⁺ in millimolar concentrations stimulated both growth and conidiation; a Ca²⁺ deprivation of the fungus by the chelation of extracellular Ca²⁺ (not Mg²⁺ or divalent trace metals) with EGTA (ethyleneglycolbis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) restricted both the vegetative growth rate and starvation-induced conidiation. Both processes were affected by either Ca²⁺ or EGTA with different efficiencies. Divalent cations (Sr²⁺, Ba²⁺, Co²⁺, Ni²⁺, Mg²⁺, Cd²⁺, Cu²⁺, Mn²⁺) and La³⁺ (inorganic Ca²⁺ blockers) in millimolar concentrations exerted complex (stimulatory, inhibitory, or biphasic) effects on growth and conidiation. In general, their effects on the two processes were mutually different either qualitatively, or quantitatively, or both. Organic Ca²⁺ antagonists (verapamil and dihydropyridines) inhibited the vegetative growth. The results show that Ca²⁺ is required for vegetative growth and conidiation, and that different Ca²⁺-dependent mechanisms may be involved in the two processes. Divalent cations could serve as a tool for investigating the relationship between growth and conidiation.     

Vanadate inhibits the production and/or release of secondary metabolites without impairing growth in several fungal species

Vanadate (NaVO₃) in concentrations between 0.1–3.0 mmol/L inhibited the production of secondary metabolites (SMs) of strains of the following species:Trichoderma viride, Penicillium purpurogenum, Penicillium citrinum, Talaromyces avellaneus, andVerticillium psalliotœ. Growth was either not affected by NaVO₃, or the inhibition of the SM production occurred at lower NaVO₃, concentrations than that of the growth. Thus, at some NaVO₃ concentration the SM production was inhibited but the growth remained unaffected. The results suggest that NaVO₃ exerts a specific action either on the SM biosynthetic pathway(s) or on the export of SMs from cells.     

Alzheimer's disease-like phosphorylation of the microtubule-associated protein tau by glycogen synthase kinase-3 in transfected mammalian cells

Background: Paired helical filaments (PHFs) are a characteristic pathological feature of Alzheimer's disease; their principal component is the microtubule-associated protein tau. The tau in PHFs (PHF-tau) is hyperphosphorylated, but the cellular mechanisms responsible for this hyperphosphorylation have yet to be elucidated. A number of kinases, including mitogen-activated protein (MAP) kinase, glycogen synthase kinase (GSK)-3α, GSK-3β and cyclin-dependent kinase-5, phosphorylate recombinant tau in vitro so that it resembles PHF-tau as judged by its reactivity with a panel of antibodies capable of discriminating between normal tau and PHF-tau, and by a reduced electrophoretic mobility that is characteristic of PHF-tau. To determine whether MAP kinase, GSK-3α and GSK-3β can also induce Alzheimer's disease-like phosphorylation of tau in mammalian cells, we studied the phosphorylation status of tau in primary neuronal cultures and transfected COS cells following changes in the activities of MAP kinase and GSK-3.Results Activating MAP kinase in cultures of primary neurons or transfected COS cells expressing tau isoforms did not increase the level of phosphorylation for any PHF-tau epitope investigated. But elevating GSK-3 activity in the COS cells by co-transfection with GSK-3α or GSK-3β decreased the electrophoretic mobility of tau so that it resembled that of PHF-tau, and induced reactivity with eight PHF-tau-selective monoclonal antibodies.Conclusion Our data indicate that GSK-3α and/or GSK-3β, but not MAP kinase, are good candidates for generating PHF-type phosphorylation of tau in Alzheimer's disease. The involvement of other kinases in the generation of PHFs cannot, however, be eliminated. Our results suggest that aberrant regulation of GSK-3 may be a pathogenic mechanism in Alzheimer's disease.     

Eurotium (Aspergillus) repens metabolites and their biological activity

Eurotium repens mycelium cultivated under static conditions was used to isolate and identify metabolities—echinulin, physcion, erythroglaucin, flavoglaucin and asperentin; the filtrate of the culture yielded asperentin 8-methylether. The broadest biological activity spectrum was displayed by asperentin which had antibacterial and antifungal effects and, at a concentration of 86 ώg/ml, caused 50 % mor7 tality inArtemia saline larvae. The highest cytotoxicity towards HeLa cells was found in physcion which caused 50 % growth inhibition at a concentration of 0.1 ώg/ml.     

Inhibition of photo-inducedTrichoderma viride conidiation by inhibitors of RNA synthesis

The photo-induced conidiation ofTrichoderma viride is suppressed by ethidium bromide, acriflavin, lomofungin and 8-quinolinol at concentrations which do not inhibit the colony growth of this deuteromycete.     

Liver Fatty Acid-binding Protein Binds Monoacylglycerol in Vitro and in Mouse Liver Cytosol

Liver fatty acid-binding protein (LFABP; FABP1) is expressed both in liver and intestinal mucosa. Mice null for LFABP were recently shown to have altered metabolism of not only fatty acids but also monoacylglycerol, the two major products of dietary triacylglycerol hydrolysis (Lagakos, W. S., Gajda, A. M., Agellon, L., Binas, B., Choi, V., Mandap, B., Russnak, T., Zhou, Y. X., and Storch, J. (2011) Am. J. Physiol. Gastrointest. Liver Physiol. 300, G803–G814). Nevertheless, the binding and transport of monoacylglycerol (MG) by LFABP are uncertain, with conflicting reports in the literature as to whether this single chain amphiphile is in fact bound by LFABP. In the present studies, gel filtration chromatography of liver cytosol from LFABP^−/− mice shows the absence of the low molecular weight peak of radiolabeled monoolein present in the fractions that contain LFABP in cytosol from wild type mice, indicating that LFABP binds sn-2 MG in vivo. Furthermore, solution-state NMR spectroscopy demonstrates two molecules of sn-2 monoolein bound in the LFABP binding pocket in positions similar to those found for oleate binding. Equilibrium binding affinities are ∼2-fold lower for MG compared with fatty acid. Finally, kinetic studies examining the transfer of a fluorescent MG analog show that the rate of transfer of MG is 7-fold faster from LFABP to phospholipid membranes than from membranes to membranes and occurs by an aqueous diffusion mechanism. These results provide strong support for monoacylglycerol as a physiological ligand for LFABP and further suggest that LFABP functions in the efficient intracellular transport of MG.