<Emphasis Type="Italic">Microdochium nivale</Emphasis> (Fr., Samuels &; Hallett): cytological analysis of the infection process in triticale (×<Emphasis Type="Italic">Triticosecale</Emphasis> Wittm.)

According to regular reports, one of the most serious diseases of winter cereal and grass varieties in moderate and cold climatic areas is pink snow mould caused by Microdochium nivale. Currently, the resistance of the economically important cereal species as triticale is not satisfactory. Moreover, there is no efficient strategy of protection against this pathogen and the understanding of plant resistance mechanisms is rather poor. Presented paper for the first time shows the cytological analysis of M. nivale infection in model triticale varieties by the use of fluorescent and light microscopy in combination with fluorescent dyes and hydrogen peroxide staining. Both, the infection level and the dynamic of the process varied for tested genotypes confirming the field and laboratory data of their different resistance to this pathogen. Moreover, our analysis showed that in both cultivars cold-hardening of seedlings delayed the mycelium growth. In both cultivars, hyphal walls and fungal penetration sites were visualized in crowns, leaf sheaths and leaves of hardened and non-hardened inoculated seedlings. For the first time the presence of the haustoria produced by M. nivale was confirmed in those tissues. Single infection hyphae usually penetrated into the host tissues via stomatal apparatuses were accompanied by the efflux of hydrogen peroxide. The data show a great potential of fluorescence techniques in studying the host plant–pathogen interactions providing a better insight into plant defence reactions that may allow elaboration of the efficient breeding strategies aimed at increasing resistance to this pathogenic fungus.     

FOS licenses early events in stem cell activation driving skeletal muscle regeneration

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Specific binding of human alpha interferon to a high affinity cell surface binding site on bovine kidney cells

Virus-induced human alpha interferon (HuIFN-alpha) derived from Namalwa cells and purified to a specific activity of 2 X 10(8) units/mg of protein was radiolabeled with 125I-labeled Bolton and Hunter reagent to a specific activity of 4-12 microCi/micrograms of protein. The binding of this 125I-IFN to bovine kidney cells was examined at 4 degrees C. Scatchard analysis of the binding data indicate the presence of 650 binding sites/cell and binding of the ligand with an apparent Kd of 6 X 10(-11) M. Trypsin or acid treatment of cells to which 125I-IFN was bound resulted in the release of greater than or equal to 77% of the radioactivity, indicating a majority of radiolabeled material was bound to the cell surface. Antibodies against human leukocyte IFN but not antibodies against human fibroblast IFN inhibited the binding of radiolabeled IFN to the cells. The binding of 125I-IFN was not inhibited by a 75-fold molar excess of mouse IFN but was inhibited 30% by a 200-fold molar excess of human beta (fibroblast) IFN. These data are compatible with the Lower biological activities of these IFNs on bovine kidney cells. Several Escherichia coli derived HuIFN-alpha s inhibited the binding of the radiolabeled IFN to the same extent as native HuIFN-alpha s, but four fragments of HuIFN-alpha 1, an E. coli-derived 86 amino acid NH2-terminal fragment as well as 3 different synthetic carboxy-terminal fragments of 140, 56, or 46 amino acids did not inhibit binding.