Hormone antagonist with broad potential     

C J  P J 《Science (New York, N.Y.)》1989,245(4924):1322

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Top quark search     

Peoples J 《Science (New York, N.Y.)》1989,246(4933):984-985

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Tools of persuasion: the conseguences of economic rhetoric     

Stigler GJ 《Science (New York, N.Y.)》1989,244(4906):839-840

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Case highlights sensitive issues     

C BJ 《Science (New York, N.Y.)》1989,245(4914):121

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Authors' reply          下载免费PDF全文

Quine JP  Strunin L 《The Canadian veterinary journal. La revue veterinaire canadienne》1989,30(1):10-11

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Cortical bone allograft for repair of a femoral fracture in a cat          下载免费PDF全文

Grognet J 《The Canadian veterinary journal. La revue veterinaire canadienne》1989,30(3):246-248

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Ontario. Canine stress syndrome          下载免费PDF全文

Kalow BI  O'brien PJ 《The Canadian veterinary journal. La revue veterinaire canadienne》1989,30(7):595

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Effects of triazole fungicides on sterol biosynthesis during spore germination of Botrytis cinerea,Venturia inaequalis and Puccinia graminis f. sp. tritici     

R. Pontzen  H. Scheinpflug 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):151-160

With three plant pathogens,Botrytis cinerea, Venturia inaequalis and Puccinia graminis f. sp.tritici, the time course of sterol biosynthesis during spore germination was examined by labeling experiments along with the question whether this pathway could be inhibited by triazole fungicides. Conidia ofB. cinerea andV. inaequalis are able to synthesize sterols immediately after the beginning of the germination process when the germ tubes have not yet emerged. On the contrary uredospores ofP. graminis start sterol biosynthesis after 6 to 8 h germination time almost at the end of the germ tube phase, indicating that sterol reserves of the spores are likely to be used for the germ tube growth.The sterol C-14 demethylation appeared to be the rate limiting step within the sterol biosynthetic pathway: the half life of 24-methylenedihydrolanosterol was less than 1 h forB. cinerea. It was more than 1 h forV. inaequalis and 3 h forP. graminis. Independent of these differences in the time course of sterol biosynthesis and in the C-14 demethylation rate, the synthesis of sterols in germinating spores was strongly inhibited by triazole fungicides in all three pathogens examined. In contrast toP. graminis, this inhibition could be demonstrated withB. cinerea andV. inaequalis even in ungerminated conidia, indicating that the fungicides were rapidly taken up and reached their target within 1 or 2 h. These results are discussed along with the question whether spore germination can be used as a bioassay for the estimation of sensitivities of triazole fungicides.  相似文献   

In vitro selection of sterol-biosynthesis-inhibitor (SBI)-resistant mutants in Monilinia fructicola (Wint.) Honey     

C. Nuninger-Ney  F. -J. Schwinn  T. Staub 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):137-150

The inherent resistance risk forMonilinia fructicola against sterol-biosynthesis inhibitors (SBIs) was estimated inin vitro andin vivo laboratory studies. Several mutant strains were selected on media amended with the triazole fungicides penconazole, etaconazole or the morpholine fungicide fenpropimorph.The potential forM. fructicola to develop resistance to the triazoles or to the morpholines was similar.The level of resistance attained did not differ for the two classes of fungicides after a single cycle of treatment with nitrosoguanidine (NTG). Attemps to select mutants with a higher level of resistance to penconazole after successive mutagenic treatments were successful. Most of the mutants were less fit than wild-type strains. Mutants with a low level of resistance had an almost normal mycelial growth rate, whereas growth of mutants with a higher level of resistance was significantly reduced. Spore production was highest in the wild-type strains, similar to the latter in a few resistant strains and less in most others. Only one mutant with an intermediate level of resistance could successfully compete in a mixed population with a wild type strain during successive infection cycles on peaches. Resistance was not stable in highly resistant mutants. Cross resistance to the inhibitors of 14-methylsterol demethylation (DMIs) tested was confirmedin vitro andin vivo for all mutant strains. One DMI-resistant mutant was also resistant to fenpropimorph and two fenpropimorph-resistant mutants were resistant to penconazole.  相似文献   

Colonization of rose by Sphaerotheca pannosa (Wallr.) Lév. var. rosae Wor.     

H. D. Frinking  R. Verweij 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):63-72

Colonization of rose by powdery mildew (Sphaerotheca pannosa) is described in terms of mycelium growth, conidiophore production and sporulation in time. The data used are gathered during different years, put together and treated by means of graphic models. Colonies could be separated into fast and slow growing colonies. Colonies initiated on leaves of increasing age showed a decreasing growth rate. Production of conidiophores and conidia started on the same day, and the relative activity of conidiophore production reached its maximum 6 days after the end of the latency period, followed 1 day later by the maximum activity of conidium production. Both conidiophore and conidium production continued for a long time at a low level. The effect of leaf age on conidiophore production found expression in differences in production rate during the first days of colony development and in final production levels. Observations on naturally infected leaves in an outdoor experiment showed a rapid decrease of sporulation on leaves of 10 days and older. Highest percentages of sporulating leaf area were observed on leaves between 7 and 10 days old.  相似文献