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73.
Loss of function of either the RVS161 or RVS167 Saccharomyces cerevisiae amphiphysin-like gene confers similar growth phenotypes that can be suppressed by mutations in sphingolipid biosynthesis. We performed a yeast two-hybrid screen using Rvs161p as bait to uncover proteins involved in this sphingolipid-dependent suppressor pathway. In the process, we have demonstrated a direct physical interaction between Rvs167p and the two-hybrid interacting proteins, Acf2p, Gdh3p, and Ybr108wp, while also elucidating the Rvs167p amino acid domains to which these proteins bind. By using subcellular fractionation, we demonstrate that Rvs167p, Ybr108wp, Gdh3p, and Acf2p all localize to Rvs161p-containing lipid rafts, thus placing them within a single compartment that should facilitate their interactions. Moreover, our results suggest that Acf2p and Gdh3p functions are needed for suppressor pathway activity. To determine pathway mechanisms further, we examined the localization of Rvs167p in suppressor mutants. These studies reveal roles for Rvs161p and the very long chain fatty acid elongase, Sur4p, in the localization and/or stability of Rvs167p. Previous yeast studies showed that rvs defects could be suppressed by changes in sphingolipid metabolism brought about by deleting SUR4 (Desfarges, L., Durrens, P., Juguelin, H., Cassagne, C., Bonneu, M., and Aigle, M. (1993) Yeast 9, 267-277). Using rvs167 sur4 and rvs161 sur4 double null cells as models to study suppressor pathway activity, we demonstrate that loss of SUR4 does not remediate the steady-state actin cytoskeletal defects of rvs167 or rvs161 cells. Moreover, suppressor activity does not require the function of the actin-binding protein, Abp1p, or Sla1p, a protein that is thought to regulate assembly of the cortical actin cytoskeleton. Based on our results, we suggest that sphingolipid-dependent suppression of rvs defects may not work entirely through regulating changes in actin organization. 相似文献
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75.
Evidence of mitochondrial involvement in the transduction of signals required for the induction of genes associated with pathogen attack and senescence 总被引:27,自引:0,他引:27
Maxwell DP Nickels R McIntosh L 《The Plant journal : for cell and molecular biology》2002,29(3):269-279
Using the mRNA differential display technique, seven cDNAs have been isolated that are rapidly induced when cultured tobacco (Nicotiana tabacum) cells are treated with the mitochondrial electron transport inhibitor antimycin A (AA). Interestingly, six of the cDNAs show distinct similarity to genes known to be induced by processes that involve programmed cell death (PCD), such as senescence and pathogen attack. All of the cDNAs as well as Aox1, a gene encoding the alternative oxidase, were found to also be strongly induced by H2O2 and salicylic acid (SA). AA, H2O2 and SA treatment of tobacco cells caused a rapid rise in intracellular ROS accumulation that, when prevented by antioxidant treatment, resulted in inhibition of gene induction. Besides AA, both H2O2 and SA were found to disrupt normal mitochondrial function resulting in decreased rates of electron transport and a lowering of cellular ATP levels. Furthermore, the pre-treatment of tobacco cells with bongkrekic acid, a known inhibitor of the mitochondrial permeability transition pore in animal cells, was found to completely block gene induction when AA, H2O2 or SA were subsequently added. These findings suggest that the mitochondrion may serve an important role in conveying intracellular stress signals to the nucleus, leading to alterations in gene expression. 相似文献
76.
L. W. Handley R. L. Nickels M. W. Cameron P. P. Moore K. C. Sink 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,71(5):691-697
Summary Leaf mesophyll protoplasts of Lycopersicon esculentum (2n=2x=24) were fused with suspension culture-derived protoplasts of Solanum lycopersicoides (2n=2x=24) and intergeneric somatic hybrid plants were regenerated following selective conditions. A two phase selection system was based on the inability of S. lycopersicoides protoplasts to divide in culture in modified medium 8E and the partial inhibition of L. esculentum protoplasts by the PEG/DMSO fusion solution. At the p-calli stage, putative hybrids were visually selected based on their hybrid vigor and lime-green coloration in contrast to slower growing parental calli characterized by a watery, whitish-brown coloration. Early identification of the eight hybrid plants studied was facilitated by isozyme analysis of leaf tissue samples taken from plants in vitro at the rooting stage. Regenerated plants growing in planting medium were further verified for hybridity by 5 isozymes marking 7 loci on 5 chromosomes in tomato. These included Skdh-1 mapped to chromosome 1 of tomato, Pgm-2 on chromosome 4, Got-2 and Got-3 on chromosome 7, Got-4 on chromosome 8, and Pgi-1 and Pgdh-2 both on chromosome 12. Fraction I protein small subunits further confirmed the hybrid nature of the plants with bands of both parents expressed in all hybrids. The parental chloroplasts could not be differentiated by the isoelectric points of the large subunit. Seven of the eight somatic hybrids had a chromosome number ranging from the expected 2n=4x=48 to 2n=68. Mixoploid root-tip cells containing 48, 53, 54 or 55 chromosomes for two of the hybrids were also observed.Michigan Agricultural Experiment Station Journal Article No. 11736. Supported by Grant No. I-751-84R from BARD — The United States — Israel Binational Agricultural Research and Development Fund 相似文献
77.
J J Quinlan J T Nickels W I Wu Y P Lin J R Broach G M Carman 《The Journal of biological chemistry》1992,267(25):18013-18020
Evidence is presented that demonstrated that the 45- and 104-kDa forms of phosphatidate phosphatase from Saccharomyces cerevisiae (Morlock, K. R., McLaughlin, J. J., Lin, Y.-P., and Carman, G. M. (1991) J. Biol. Chem. 266, 3586-3593) were regulated differentially by phosphorylation. Purified 45-kDa phosphatidate phosphatase was phosphorylated by cAMP-dependent protein kinase whereas purified 104-kDa phosphatidate phosphatase was not phosphorylated. cAMP-dependent protein kinase catalyzed the phosphorylation of pure 45-kDa phosphatidate phosphatase at a serine residue which resulted in a stimulation (2.4-fold) of phosphatidate phosphatase activity. Alkaline phosphatase catalyzed the dephosphorylation of pure 45-kDa phosphatidate phosphatase which resulted in an inhibition (1.3-fold) of phosphatidate phosphatase activity. Results of studies using mutants (bcy1 and cyr1) defective in cAMP-dependent protein kinase activity corroborated the results of the phosphorylation studies using pure preparations of phosphatidate phosphatase. The 45-kDa phosphatidate phosphatase phosphorylated in vitro and in vivo had phosphopeptides in common. The activation of the GAL10-RAS2val19 allele in mutant cells resulted in an increase in the synthesis of diacylglycerols and triacylglycerols. These results were consistent with the phosphorylation and activation of 45-kDa phosphatidate phosphatase by cAMP-dependent protein kinase in vivo. 相似文献
78.
Previously it has been shown that the levels of xanthine dehydrogenase in chick liver can be increased by feeding high-protein diets, adenine, and allopurinol (a xanthine dehydrogenase inhibitor). Also, it has been shown that starvation increases the level of xanthine dehydrogenase in chick liver and that unsaturated fatty acids in the diet suppress the levels of xanthine dehydrogenase in the liver. Results reported here show that starvation and high-protein diets enhance the levels of purine nucleoside phosphorylase and that unsaturated fatty acids suppress the level of this enzyme. In contrast with xanthine dehydrogenase, adenine and allopurinol have no effect on purine nucleoside phosphorylase levels. These results suggest that dietary protein and unsaturated fatty acids regulate more than one enzyme involved in the production of uric acid.Levels of xanthine dehydrogenase in the pancreas can be increased by feeding and decreased by starvation or feeding unsaturated fatty acids. None of these procedures has any effect on the level of pancreatic purine nucleoside phosphorylase. 相似文献
79.
Effect of Silicate Grain Shape, Structure, and Location on the Biomass and Community Structure of Colonizing Marine Microbiota 总被引:1,自引:0,他引:1 下载免费PDF全文
Janet S. Nickels Ronald J. Bobbie Robert F. Martz Glen A. Smith David C. White Norman L. Richards 《Applied microbiology》1981,41(5):1262-1268
Microbiota colonizing silica grains of the same size and water pore space, but with a different microtopography, showed differences in biomass and community structure after 8 weeks of exposure to running seawater. The absence of surface cracks and crevices resulted in a marked diminution of the total microbial biomass measured as lipid phosphate and total extractable palmitic acid. With increasing smoothness of the sand grain surface, examination of the community structure showed a marked decrease in procaryotes and algal microeucaryotes, with a relative increase in microeucaryotic grazers. A comparison of the colonizing sediment incubated in running seawater or at 32 m on the sea floor with a sediment core showed a decreased bacterial biomass with a different community structure and a decreased total microeucaryotic population of both grazers and algae. The quantitative differences in microbial biomass and community structure between the microcosms and the actual benthic population in the core were determined. 相似文献
80.
López-Valenzuela BE Armenta-Bojórquez AD Hernández-Verdugo S Apodaca- Sánchez MA Samaniego-Gaxiola JA Valdez-Ortiz A 《Phyton》2019,88(1):37-46
Microbes that are beneficial to plants are used to
enhance the crop growth, yield and are alternatives to chemical
fertilizers. Trichoderma and Bacillus are the predominant plant
growth-promoting fungi and bacteria. The objective of this study
was select, characterize, and evaluate isolates of Trichoderma
spp. and Bacillus spp. native from the northern region of Sinaloa,
Mexico, and assess their effect on growth promotion in maize (Zea
mays L.). In greenhouse conditions, four Trichoderma isolates and
twenty Bacillus isolates, as well as two controls, were tested in a
completely randomized design with three replicates. We selected
the two best strains of Trichoderma and Bacillus: TB = Trichoderma
asperellum, TF = Trichoderma virens, B14 = Bacillus cereus sensu
lato and B17 = Bacillus cereus, which were evaluated in the field in
a completely randomized blocks in factorial arrangement design
with three replicates applying different rates of nitrogen fertilizer
(0, 150 kg N/ha, and 300 kg N/ha). Treatments 5 (B17 = B. cereus)
and 11 (TF = T. virens) both fertilized with 150 kg N/ha showed
similar yields and they did not reveal significant differences from
the treatments fertilized with 300 kg N/ha. This indicated that
treatment 5 (B17= B. cereus with 150 kg N/ha) and treatment
11 (TF= T. virens with 150 kg N/ha) were efficient as growth
promoters, by not showing significant differences in root volume
and dry weight of foliage. The results indicated a reduction of 50%
in the rate of nitrogen to fertilizer required for maize (Zea mays
L.) crops. These microorganisms Trichoderma and Bacillus could
be an alternative to reduce the use of chemical fertilizers in maize. 相似文献