This paper reports brief systematization of the current knowledge of the biology of mycoviruses, viral morphology, and genetics in particular as well as characteristics of the virus transmission and infection symptoms in fungal cells. The mechanisms involved in antiviral defense in the members of different classes of fungi are discussed. Insights into the role of hypovirulent mycoviruses in the biotechnological control of phytopathogenic fungi are provided.
Alternaria species isolated from different econiches produce a wide variety of biologically active metabolites. The aim of this article was the evaluation of the biological activity spectrum of the small-spored Alternaria species from different trophic groups (saprophytes, endophytes and plant pathogens) using screening of biologically active metabolites on a wide set of test organisms, and selection of promising strainsproducers. Methods. Antibiotic, antifungal and phytotoxic activities of culture filtrates and chloroform extracts were determined by agar diffusion assay method. Results. 19% of cultural filtrates among of 64 studied strains showed the biological activity at least against one test organism. The most of these fungi belong to endophytic strains and were active against test plant pathogenic fungi, bacteria and algae. Chloroform extracts of cultural filtrates of 33% of fungi showed biological activity against at least to one test organism. The obtained extracts had specific activity mainly against certain test culture. These preparations selectively inhibited the growth of Staphylococcus aureus B-909, Chlorella vulgaris 191 and Rizoctonia solani 16036. Conclusions. The screening of 64 strains of the Alternaria fungi isolated from different ecological niches allows concluding that they have low biological activity. Endophytic Alternaria strains were characterized by wider spectrum of activities than plant pathogenic and soil ones. They inhibited all test organisms except Gram negative bacteria and yeast-like fungi. The biologically active metabolites of endophytic Alternaria strains including high-molecular compounds play important role in mutual coexistence endophytic fungi and host-plants as well as their spread. Chloroform extracts of the soil saprophytes had comparably high activity especially against fungi and algae. Obviously these low-molecular compounds facilitate to adaptive survival of saprophytic fungi in soil habitats with high biodiversity. For further studies were selected two strains: highly phytotoxic A. brassicicola 2855 and A. longipes 16800 (an antagonist of S. aureus B-909).
Исследованы образцы кремнеземов, модифицированных соединениями серебра и парой металлов серебро-медь. Содержание серебра составляло от 1,0 до 0,01 ммоль/г SiO 2 , а меди -0,2 -0,1 ммоль/г. Методами рентгенофазового анализа и электронной спектроскопии исследованы изменения соединений серебра в кремнеземной матрице при световом старении в течение 7-30 дней. Установлено возрастание содержания кристаллического Ag 0 , при этом существенных изменений в фунгицидной активности не наблюдалось.
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