摘要:

AbstractPhotobleaching diphenyl ether, cyclic imide and oxadiazole herbicides inhibit protoporphyrinogen oxidase (Protox), resulting in uncontrolled, non‐enzymic oxidation of accumulated protoporphyrinogen to protoporphyrin IX (Proto). Proto accumulation is stimulated by deregulation of the porphoyrin pathway due to blockage of heme synthesis. Heme is a Proto product and a feedback inhibitor of δ‐aminolevulinic acid synthesis. Strong correlations were found in several species under various conditions (e.g. sprayed on intact plants or taken up by leaf dises) between the accumulation of Proto and the degree of herbicidal damage caused by these herbicides. Levels of protochlorophyllide, Mg‐Proto, or Mg‐Proto monomethyl ester did not correlate significantly with herbicidal damage. Kinetic data indicated that elevated levels of protochlorophyllide in tissues treated with these herbicides only occurred after Proto had accumulated to high levels. Thus, Proto apparently re‐enters the porphyrin pathway to a significant extent after other cellular sites are saturated. Fluorescence microscopy indicated that considerable amounts of Proto accumulated outside the plastid in herbicide‐treated cells. All of the data were consistent with the hypothesis that Proto plays a critical role as a photosensitizing pigment in the mode of action of Protox‐inhibiting herbicides and that chlorophyll precursors that are derivatives of Proto are not significantly involved in the mode of action of th

ISSN:0031-613X    

DOI:10.1002/ps.2780300402

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSensory fibres in the isolated metathoracic leg of houseflies were used as a neurophysiological assay to investigate nerve insensitivity factors in knockdown‐resistant strains (kdr, super‐kdr) against DDT, the pyrethroids deltamethrin and RU15525, and the N‐alkyl amide BTG502. Several neurophysiological effects were induced by these compounds, but the only consistent one was an elevation of the spontaneously occurring firing rate. Whilst both resistant strains possess a nerve insensitivity factor, that of the more resistant super‐kdr flies appeared to be weaker than that of kdr. When probed with BTG502, super‐kdr nerves were no more resistant to this compound than those of the susceptible Cooper strain. Kdr nerves were considerably less sensitive (at least 100‐fold) than either of these other two strains. These results indicate that the voltage‐dependent sodium channels are different in all three strains and that the higher resistance shown by super‐kdr over kdr flies cannot be accounted for by simple enhancement of the kdr nerve‐insensitivity factor. Therefore, target sites other than the voltage‐dependent sodium channel have to be considered to account, fully for super‐kdr resistance. Such sites could occur at synaptic contacts, possibly involving phosphorylation of proteins and/or c

ISSN:0031-613X    

DOI:10.1002/ps.2780300403

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSynthetic analogues of arthropod polyamine‐containing toxins have been investigated for antagonism of the quisqualate‐sensitive L‐glutamate receptor (quis‐GluR) of locust muscle. Block of the cation‐selective channel gated by quis‐GluR was demonstrated for N‐(4‐hydroxyphenylpropanoyl)‐and N‐(4‐hydroxyphenylacetyl)‐spermine at significantly lower concentrations

ISSN:0031-613X    

DOI:10.1002/ps.2780300404

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSensitivity patterns of Venturia nashicola strains to ergosterol biosynthesis inhibitors (EBIs) were explored in order to obtain ‘base‐line’ data. For triflumizole or bitertanol, sensitivity was examined in mycelial growth tests and comparisons were based on EC50rather than MIC values. It was also indicated that measurements of germ‐tube length rather than observation of conidial germination or septum formation were needed to assess sensitivity to these fungicides as a rapid and simple method. Field trials were carried out to examine how fast EBIs might select for lower sensitivity in field populations of V. nashicola. Results suggested that any shifts to lower EBI sensitivity in this fungus would not proceed very quickly. It might be possible to avoid potential problems of EBI resistance and maintain the long‐term effectiveness of EBI fungicides in orchards by applying them

ISSN:0031-613X    

DOI:10.1002/ps.2780300405

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0031-613X    

DOI:10.1002/ps.2780300406

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0031-613X    

DOI:10.1002/ps.2780300401

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY