Browsing by Author "MUNOZ, GA"

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    COMPARISON OF AERIAL AND SUBMERGED SPORE PROPERTIES FOR TRICHODERMA-HARZIANUM
    (ELSEVIER SCIENCE BV, 1995) MUNOZ, GA; AGOSIN, E; COTORAS, M; SANMARTIN, R; VOLPE, D
    Spores produced by aerial mycelium of Trichoderma harzianum P1, a potential biocontrol agent, showed both higher UV-resistance and longer viability after storage than those produced within liquid media ('submerged' spores). Aerial spores were produced in clusters, had a thick outer wall, and few organelles. Trehalose content was significantly lower than in submerged spores. Conversely, submerged spores were mostly collapsed, not clustered and larger than aerial spores. They had many cytoplasmic organelles and a thinner outer wall. These spores were hydrophilic, while aerial ones were highly hydrophobic. On analysis, the latter was related with the presence of a single major low molecular mass protein (< 14 kDa). This protein was nearly absent in extracts from walls of submerged spores but was found in the extracellular medium. An involvement of the outer wall layer in the resting state of T. harzianum spores is proposed.
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    GLUTAMINE INVOLVEMENT IN NITROGEN CONTROL OF GIBBERELLIC-ACID PRODUCTION IN GIBBERELLA-FUJIKUROI
    (AMER SOC MICROBIOLOGY, 1993) MUNOZ, GA; AGOSIN, E
    When the fungus Gibberella fujikuroi ATCC 12616 was groWn in fermentor cultures, both intracellular kaurene biosynthetic activities and extracellular GA3 accumulation reached high levels when exogenous nitrogen was depleted in the culture. Similar patterns were exhibited by several nonrelated enzymatic activities, such as formamidase and urease, suggesting that all are subject to nitrogen regulation. The behavior of the enzymes involved in nitrogen assimilation (glutamine synthetase, glutamate dehydrogenase, and glutamate synthase) during fungal growth in different nitrogen sources suggests that glutamine is the final product of nitrogen assimilation in G. fujikuroi. When ammonium or glutamine was added to hormone-producing cultures, extracellular GA3 did not accumulate. However, when the conversion of ammonium into glutamine was inhibited by L-methionine-DL-sulfoximine, only glutamine maintained this effect. These results suggest that glutamine may well be the metabolite effector in nitrogen repression of GA3 synthesis, as well as in other nonrelated enzymatic activities in G. fujikuroi.