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81.
Specific Inhibition of the Cyanide-insensitive Respiratory Pathway in Plant Mitochondria by Hydroxamic Acids 总被引:77,自引:44,他引:33 下载免费PDF全文
Gregory R. Schonbaum Walter D. Bonner Jr. Bayard T. Storey James T. Bahr 《Plant physiology》1971,47(1):124-128
Hydroxamic acids, R-CONHOH, are inhibitors specific to the respiratory pathway through the alternate, cyanide-insensitive terminal oxidase of plant mitochondria. The nature of the R group in these compounds affects the concentration at which the hydroxamic acids are effective, but it appears that all hydroxamic acids inhibit if high enough concentrations are used. The benzhydroxamic acids are effective at relatively low concentrations; of these, the most effective are m-chlorobenzhydroxamic acid and m-iodobenzhydroxamic acid. The concentrations required for half-maximal inhibition of the alternate oxidase pathway in mung bean (Phaseolus aureus) mitochondria are 0.03 mm for m-chlorobenzhydroxamic acid and 0.02 mm for m-iodobenzhydroxamic acid. With skunk cabbage (Symplocarpus foetidus) mitochondria, the required concentrations are 0.16 for m-chlorobenzhydroxamic acid and 0.05 for m-iodobenzhydroxamic acid. At concentrations which inhibit completely the alternate oxidase pathway, these two compounds have no discernible effect on either the respiratory pathway through cytochrome oxidase, or on the energy coupling reactions of these mitochondria. These inhibitors make it possible to isolate the two respiratory pathways and study their mode of action separately. These inhibitors also enhance an electron paramagnetic resonance signal near g = 2 in anaerobic, submitochondrial particles from skunk cabbage, which appears to be specific to the alternate oxidase and thus provides a means for its assay. 相似文献
82.
Changes in Ribonucleic Acid Fractions During Maturation of Mimosa Epicotyl Tissues 总被引:1,自引:1,他引:0 下载免费PDF全文
Gregory N. Brown 《Plant physiology》1969,44(2):272-276
Total RNA and DNA of mimosa epicotyl tissues were extracted and the RNA fractionated into specific soluble RNAs (sRNAs) at different times during late germination. Epicotyls collected at each time contained qualitatively comparable meristematic and developing tissues, while mature tissues increased. Quantitative ratios of total RNA to DNA and total sRNAs to approximated ribosomal RNA (rRNA) varied consistently during development. Terminal nucleosides of sRNA did not vary in any consistent pattern through development. On the other hand, regular changes in quantitative ratios of specific sRNA groups were observed during development. 相似文献
83.
Cellular evolution in induced inflammation in uremic patients 总被引:2,自引:0,他引:2
84.
85.
Gregory B. Pollock 《Journal of evolutionary biology》1989,2(3):205-221
Critique of Wynne-Edwards' views on population regulation and sociality suppose a population of discrete, mutually exclusive groups essential to his thought. Yet both his past and present work focus on continually distributed, philopatric populations; his critics have argued the untenability of a position never his own. Wynne-Edwardsian ‘group selection’ focuses on local population productivity under philopatry. A ‘group’ is a local confluence of genotypes which need not be reified, and group selection consists of the differential replication (hence heritability) of the local social environment in which a genotype is embedded. Differential productivity contingent on social environment can eliminate some relational structures on genotypes in favor of others, creating an expanding wave of population productivity as in Wright's shifting balance metaphor. Such a process is inherent in the evolution of reciprocity, where cooperators must cluster to successfully invade a population of defectors. Regulation of resource exploitation in continuously distributed populations may be modeled as overlapping n-person Prisoner's Dilemmas, where each individual participates in several distinct commons and defection represents local over-exploitation of resources. 相似文献
86.
87.
Developmental Expression of Go in Neuronal Cultures from Rat Mesencephalon and Hypothalamus 总被引:1,自引:1,他引:0
The developmental expression of the alpha-subunit of Go was examined in neuronal cultures derived from rat mesencephalon (MES) and hypothalamus (HYP). These cultures were essentially free of contaminating glia and were maintained as a stable population for periods up to 3 weeks. Immunoblotting utilizing specific antisera against Go indicated that in neurons from both brain regions, membrane concentrations of Go increased dramatically during the first 2 weeks in vitro. Thereafter, increases in the amount of Go per neuron kept pace with increasing process (axons and dendrites) formation. Multiple forms of immunoreactive Go were detected in MES and HYP neurons, and the proportions of these forms changed between 4 and 14 days in culture. Finally, increasing neuron density significantly increased membrane levels of Go in MES but not HYP cultures. 相似文献
88.
Epstein-Barr virus latent membrane protein (LMP1) and nuclear proteins 2 and 3C are effectors of phenotypic changes in B lymphocytes: EBNA-2 and LMP1 cooperatively induce CD23. 总被引:99,自引:66,他引:33 下载免费PDF全文
F Wang C Gregory C Sample M Rowe D Liebowitz R Murray A Rickinson E Kieff 《Journal of virology》1990,64(5):2309-2318
Latent Epstein-Barr virus (EBV) infection and growth transformation of B lymphocytes is characterized by EBV nuclear and membrane protein expression (EBV nuclear antigen [EBNA] and latent membrane protein [LMP], respectively). LMP1 is known to be an oncogene in rodent fibroblasts and to induce B-lymphocyte activation and cellular adhesion molecules in the EBV-negative Burkitt's lymphoma cell line Louckes. EBNA-2 is required for EBV-induced growth transformation; it lowers rodent fibroblast serum dependence and specifically induces the B-lymphocyte activation antigen CD23 in Louckes cells. These initial observations are now extended through an expanded study of EBNA- and LMP1-induced phenotypic effects in a different EBV-negative B-lymphoma cell line, BJAB. LMP1 effects were also evaluated in the EBV-negative B-lymphoma cell line BL41 and the EBV-positive Burkitt's lymphoma cell line, Daudi (Daudi is deleted for EBNA-2 and does not express LMP). Previously described EBNA-2- and LMP1-transfected Louckes cells were studied in parallel. EBNA-2, from EBV-1 strains but not EBV-2, induced CD23 and CD21 expression in transfected BJAB cells. In contrast, EBNA-3C induced CD21 but not CD23, while no changes were evident in vector control-, EBNA-1-, or EBNA-LP-transfected clones. EBNAs did not affect CD10, CD30, CD39, CD40, CD44, or cellular adhesion molecules. LMP1 expression in all cell lines induced growth in large clumps and expression of the cellular adhesion molecules ICAM-1, LFA-1, and LFA-3 in those cell lines which constitutively express low levels. LMP1 expression induced marked homotypic adhesion in the BJAB cell line, despite the fact that there was no significant increase in the high constitutive BJAB LFA-1 and ICAM-1 levels, suggesting that LMP1 also induces an associated functional change in these molecules. LMP1 induction of these cellular adhesion molecules was also associated with increased heterotypic adhesion to T lymphocytes. The Burkitt's lymphoma marker, CALLA (CD10), was uniformly down regulated by LMP1 in all cell lines. In contrast, LMP1 induced unique profiles of B-lymphocyte activation antigens in the various cell lines. LMP1 induced CD23 and CD39 in BJAB; CD23 in Louckes; CD39 and CD40 in BL41; and CD21, CD40, and CD44 in Daudi. In BJAB, CD23 surface and mRNA expression were markedly increased by EBNA-2 and LMP1 coexpression, compared with EBNA-2 or LMP1 alone. This cooperative effect was CD23 specific, since no such effect was observed on another marker, CD21.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
89.
90.
Defective intracellular transport and processing of CFTR is the molecular basis of most cystic fibrosis. 总被引:113,自引:0,他引:113
S H Cheng R J Gregory J Marshall S Paul D W Souza G A White C R O'Riordan A E Smith 《Cell》1990,63(4):827-834
The gene associated with cystic fibrosis (CF) encodes a membrane-associated, N-linked glycoprotein called CFTR. Mutations were introduced into CFTR at residues known to be altered in CF chromosomes and in residues believed to play a role in its function. Examination of the various mutant proteins in COS-7 cells indicated that mature, fully glycosylated CFTR was absent from cells containing delta F508, delta 1507, K464M, F508R, and S5491 cDNA plasmids. Instead, an incompletely glycosylated version of the protein was detected. We propose that the mutant versions of CFTR are recognized as abnormal and remain incompletely processed in the endoplasmic reticulum where they are subsequently degraded. Since mutations with this phenotype represent at least 70% of known CF chromosomes, we argue that the molecular basis of most cystic fibrosis is the absence of mature CFTR at the correct cellular location. 相似文献