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W. Scott Armbruster 《American journal of botany》1982,69(9):1429-1440
Patterns of capsule development and methods of seed dispersal are described and compared for 16 neotropical species of Dalechampia. In 15 species all the capsules in a single inflorescence develop simultaneously. In one species, D. spathulata, the capsules develop sequentially. I suggest that the difference between D. spathulata and the other species is the result of the fact that D. spathulata occurs in a low-light, rainforest environment, whereas the other species grow in high-light environments. Sequential development of capsules appears to reduce the loss of seeds to seed predators in species that occur in light-limited environments. The seeds of all 16 species of Dalechampia are dispersed by explosive dehiscence of the capsules. Within the genus there are several different adaptations that increase the average dispersal distance for the seed crop. 相似文献
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Treatment of membranes from guinea-pig peritoneal eosinophils with deoxycholate and NaCl solubilized greater than 95% of the particulate cyclic AMP-specific phosphodiesterase (PDE IV). Solubilized PDE IV was at least 10 times more potently inhibited by selective PDE IV inhibitors (e.g. rolipram, denbufylline) than bound enzyme. Vanadate/glutathione complex (V/GSH) activated membrane-bound PDE IV and also increased potencies of these same inhibitors by at least 10-fold. Neither solubilization nor V/GSH markedly influenced the inhibitory activities of non-selective inhibitors (e.g. trequinsin, dipyridamole). Inhibitor effects on solubilized PDE IV and cyclic AMP accumulation in intact cells were strongly correlated. These results suggest a biologically important site on eosinophil PDE IV which is concealed or partially concealed in freshly prepared membranes and is exposed by solubilization or V/GSH. 相似文献
107.
Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible. 相似文献
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Several mutants of Pseudomonas syringae subsp. savastanoi were tested for their ability to sense and respond to a chemotactic gradient in low concentrations of yeast extract. The mutants were deficient in one or both of the genes coding for the synthesis of the plant hormones indole-3-acetic acid (IAA) and isopentenyl adenosine. Mutations which resulted in the loss of IAA production were due to the loss of the entire plasmid containing the iaa operon or to an 18-kb deletion of the iaa region. Additional mutants tested were deficient in their ability to produce isopentenyl adenosine as a result of the loss of the ptz-bearing plasmid. In all cases, strains which had lost the ability to produce IAA exhibited enhanced motility of up to 2.5 times that of the wild type (IAA+) in medium containing 0.01% yeast extract. No differences in motility were observed on medium containing lower concentrations of yeast extract. The presence or absence of the cytokinin plasmid and the presence or absence of inorganic nitrogen in the medium had no effect on the relative mobility of the strains. 相似文献
110.
Induction of beta-1,3-glucanase in barley in response to infection by fungal pathogens. 总被引:2,自引:0,他引:2
W Jutidamrongphan J B Andersen G Mackinnon J M Manners R S Simpson K J Scott 《Molecular plant-microbe interactions : MPMI》1991,4(3):234-238
The sequence of a partial cDNA clone corresponding to an mRNA induced in leaves of barley (Hordeum vulgare) by infection with fungal pathogens matched almost perfectly with that of a cDNA clone coding for beta-1,-3-glucanase isolated from the scutellum of barley. Western blot analysis of intercellular proteins from near-isogenic barley lines inoculated with the powdery mildew fungus (Erysiphe graminis f. sp. hordei) showed a strong induction of glucanase in all inoculated lines but was most pronounced in two resistant lines. These data were confirmed by beta-1,3-glucanase assays. The barley cDNA was used as a hybridization probe to detect mRNAs in barley, wheat (Triticum aestivum), rice (oryza sativus), and sorghum (Sorghum bicolor), which are induced by infection with the necrotrophic pathogen Bipolaris sorokiniana. These results demonstrate that activation of beta-1,3-glucanase genes may be a general response of cereals to infection by fungal pathogens. 相似文献