Showing papers by "Kevin C. Vaughn published in 1981"
TL;DR: Tentoxin-treated mung bean plants are shown to lack chloroplast polyphenol oxidase (PPO) by enzymatic, electrophoretic and cytochemical analysis, and it is unlikely that the primary effect of tentoxin is due to the binding of thechloroplast coupling factor, as previously supposed.
Abstract: Tentoxin-treated mung bean plants are shown to lack chloroplast polyphenol oxidase (PPO) by enzymatic, electrophoretic and cytochemical analysis. Incorporation of PPO (a protein coded by nuclear DNA) into the plastid may occur via concentration of the protein into inner envelope-derived vesicles. PPO integration into the plastid is apparently blocked by a tentoxin treatment although fraction I protein (and hence the proteins for chloroplast ribosome production) is not affected by this fungal toxin. Both apical and etiolated plastids from teotoxin-treated plants lack PPO. Thus, it is unlikely that the primary effect of tentoxin is due to the binding of the chloroplast coupling factor, as previously supposed.
63 citations
TL;DR: A developmental study revealed that, although all leaf plastid types near the basal meristem were ultrastructurally similar, the mesophyll and bundle sheath plastids were already differentiated with respect to PPO activity.
Abstract: Plastidic polyphenol oxidase (PPO) was localized in various plastid types ofSorghum bicolor (L.) Moench using cytochemical and biochemical franctionation techniques. PPO was found to be present in the mesophyll plastids yet absent from the bundle sheath and guard cell plastids. Mechanical fractionation of mesophyll and bundle sheath plastids, with subsequent electrophoretic or spectrophotometric assay of the preparations, also indicated that PPO was absent from the bundle sheath but present in the mesophyll fraction. A developmental study revealed that, although all leaf plastids near the basal meristem were ultrastructurally similar, the mesophyll and bundle sheath plastids were already differentiated with respect to PPO activity.
32 citations
16 citations
TL;DR: NADH-dependent nitrate reductase (E.C.6.1) was ultrastructurally localized in norflurazon-treated and control soybean cotyledons by a method based upon the increase in osmiophilia due to the formation of an azo dye, suggesting a degree of specificity of this cytochemical procedure.
Abstract: NADH-dependent nitrate reductase (E.C. 1.6.6.1) was ultrastructurally localized in norflurazon-treated and control soybean cotyledons [Glycine max (L.) Merr.] by a method based upon the increase in osmiophilia due to the formation of an azo dye. The reaction product was observed in small vesicles throughout the cytoplasm. An apparent transport of nitrite to the plastid, the site of nitrite reduction, may occur through fusion of the nitrite-containing vesicles with the chloroplast envelope. Plants grown in tungstate lacked nitrate reductase activity as measured by standard assay procedures, and showed no increase in osmiophilia, suggesting a degree of specificity of this cytochemical procedure.
12 citations
TL;DR: Plastid fusions were noted in an ultrastrucutal study of a mutant of Hosta showing slow sorting out of plastid genes, suggesting that fusions between wild type and mutant plastids might increase the mixing of plasts and hence slow the process of sorting out.
Abstract: Plastid fusions were noted in an ultrastrucutal study of a mutant of Hosta showing slow sorting out of plastid genes. These data suggest that fusions between wild type and mutant plastids might increase the mixing of plastid DNA and hence slow the process of sorting out. It is likely that peripheral reticula are involved in the process of plastid fusion between the mutant and wild-type plastids.
10 citations
TL;DR: The cytochemical localization of PS II donor sites on the lumen side is consistent with flash photolysis and diaminobenzenesulfonic acid inactivation studies as well as the chemiosmotic theory for the generation of a proton gradient.
Abstract: Tetramethylbenzidene, an artificial donor of electrons to the photosystem (PS) II reaction center, is oxidized to an osmiophilic polymer that allows for the localization of the donor site of PS II. Mesophyll chloroplasts of Sorghum bicolor (L.) Moench. contain 0.1-0.2 micron deposits only in the grana stacks and on the lumen side of the thylakoid. Agranal mature bundle sheath plastids (known to be devoid of PS II activity) show little deposition and the products appear randomly distributed along the lamellae. The cytochemical localization of PS II donor sites on the lumen side is consistent with flash photolysis and diaminobenzenesulfonic acid inactivation studies as well as the chemiosmotic theory for the generation of a proton gradient.
5 citations