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991.
Analysis of the Arabidopsis Mitochondrial Proteome 总被引:1,自引:0,他引:1
A. Harvey Millar Lee J. Sweetlove Philippe Gieg Christopher J. Leaver 《Plant physiology》2001,127(4):1711-1727
992.
Francis L. Martin Kathleen J. Cole J. Andrew Williams Barbara C. Millar David Harvey Gillian Weaver Philip L. Grover David H. Phillips 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2000,470(2):289
Exfoliated cells, isolated from breast milk samples donated by UK-resident women (n=15), were incubated, either immediately or after culture for 7 days, with one of a series of genotoxins, either in the presence or absence of the DNA-repair inhibitors, hydroxyurea (HU), and cytosine arabinoside (ara-C). The numbers of DNA single-strand breaks induced were then assessed as comet tail length (CTL) (μm) using the alkaline single cell–gel electrophoresis (‘Comet’) assay; cell viability was measured by trypan blue exclusion. The heterocyclic aromatic amines (HAAs) (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) (0.4 mM), 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) (1.67 mM), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) (1.77 mM)), a polycyclic aromatic hydrocarbon (benzo[a]pyrene (B[a]P) (0.36 mM)), a nitro-polycyclic aromatic hydrocarbon (1-nitropyrene (1-NP) (1.84 mM)) and aromatic amines (o-toluidine (0.85 mM), p-chloroaniline (0.71 mM)) each induced statistically significant (P<0.0001, Mann–Whitney test) increases in median CTLs in breast milk cells from all the donors examined when incubated (30 min, 37°C) in the presence of HU/ara-C. In some cases, these compounds were also active in the absence of the repair inhibitors. There were marked variations in comet formation between donors and between genotoxins. Cell culture appeared to increase the epithelial cell proportion and cultured cells retained their ability to activate genotoxins. The results suggest that breast milk is a valuable source of human mammary cells for the study of the metabolic activation of possible carcinogens. 相似文献
993.
Millar AA Jacobsen JV Ross JJ Helliwell CA Poole AT Scofield G Reid JB Gubler F 《The Plant journal : for cell and molecular biology》2006,45(6):942-954
We have investigated the relationship between seed dormancy and abscisic acid (ABA) metabolism in the monocot barley and the dicot Arabidopsis. Whether dormant (D) or non-dormant (ND), dry seed of Arabidopsis and embryos of dry barley grains all had similarly high levels of ABA. ABA levels decreased rapidly upon imbibition, although they fell further in ND than in D. Gene expression profiles were determined in Arabidopsis for key ABA biosynthetic [the 9-cis epoxycarotenoid dioxygenasegene family] and ABA catabolic [the ABA 8'-hydroxylase gene family (CYP707A)] genes. Of these, only the AtCYP707A2 gene was differentially expressed between D and ND seeds, being expressed to a much higher level in ND seeds. Similarly, a barley CYP707 homologue, (HvABA8'OH-1) was expressed to a much higher level in embryos from ND grains than from D grains. Consistent with this, in situ hybridization studies showed HvABA8'OH-1 mRNA expression was stronger in embryos from ND grains. Surprisingly, the signal was confined in the coleorhiza, suggesting that this tissue plays a key role in dormancy release. Constitutive expression of a CYP707A gene in transgenic Arabidopsis resulted in decreased ABA content in mature dry seeds and a much shorter after-ripening period to overcome dormancy. Conversely, mutating the CYP707A2 gene resulted in seeds that required longer after-ripening to break dormancy. Our results point to a pivotal role for the ABA 8'-hydroxylase gene in controlling dormancy and that the action of this enzyme may be confined to a particular organ as in the coleorhiza of cereals. 相似文献
994.
Claessens TE Georgakopoulos D Afanasyeva M Vermeersch SJ Millar HD Stergiopulos N Westerhof N Verdonck PR Segers P 《American journal of physiology. Heart and circulatory physiology》2006,290(4):H1474-H1483
The linear time-varying elastance theory is frequently used to describe the change in ventricular stiffness during the cardiac cycle. The concept assumes that all isochrones (i.e., curves that connect pressure-volume data occurring at the same time) are linear and have a common volume intercept. Of specific interest is the steepest isochrone, the end-systolic pressure-volume relationship (ESPVR), of which the slope serves as an index for cardiac contractile function. Pressure-volume measurements, achieved with a combined pressure-conductance catheter in the left ventricle of 13 open-chest anesthetized mice, showed a marked curvilinearity of the isochrones. We therefore analyzed the shape of the isochrones by using six regression algorithms (two linear, two quadratic, and two logarithmic, each with a fixed or time-varying intercept) and discussed the consequences for the elastance concept. Our main observations were 1) the volume intercept varies considerably with time; 2) isochrones are equally well described by using quadratic or logarithmic regression; 3) linear regression with a fixed intercept shows poor correlation (R(2) < 0.75) during isovolumic relaxation and early filling; and 4) logarithmic regression is superior in estimating the fixed volume intercept of the ESPVR. In conclusion, the linear time-varying elastance fails to provide a sufficiently robust model to account for changes in pressure and volume during the cardiac cycle in the mouse ventricle. A new framework accounting for the nonlinear shape of the isochrones needs to be developed. 相似文献
995.
Horan M Newsway V Yasmin Lewis MD Easter TE Rees DA Mahto A Millar DS Procter AM Scanlon MF Wilkinson IB Hall IP Wheatley A Blakey J Bath PM Cockcroft JR Krawczak M Cooper DN 《Human genetics》2006,119(5):527-540
An increased prevalence of both hypertension and cerebrovascular stroke is apparent in growth hormone (GH) deficiency whilst hypertension is a frequent complication in acromegaly. This has suggested a possible link between GH, stature and arterial function. Since the risk of both hypertension and stroke also appears to be inversely correlated with adult height, we have instigated an exploratory study to assess whether inter-individual variation in the genes encoding human growth hormone (GH1) and the GH receptor (GHR) might be associated with an increased risk of hypertension and stroke. GH1 promoter haplotypes were found to differ significantly not only between hypertensive patients (n=111) and controls (n=121) but also between stroke patients (n=155) and controls (n=158). Intriguingly, the association between GH1 promoter haplotype and risk of hypertension was much greater in females than in males. An inverse correlation between height and central systolic blood pressure was apparent in both hypertensive patients and normal controls but was much stronger in individuals carrying at least one GH1 promoter risk haplotype. The GH1 genotype therefore constitutes a risk factor for hypertension that interacts with stature. A strong association was found between the presence of at least one GH1 risk haplotype and a family history of stroke at an early age (odds ratio: 9.07, 95% confidence interval: 1.14–72.22). Three novel GH variants (Arg16His, Phe176Cys, Cys189Arg) were identified during the course of this study. Although two exhibited markedly reduced biological activity in vitro, their clinical significance remains unclear. No association was found between GHR genotype and either hypertension or stroke, nor was any interaction noted between GHR and GH1 genotypes in terms of a disease association. However, an association between GHRd3 genotype and hypertension was observed among stroke patients, particularly females. Elevated HDL was found to be a risk factor for hypertension in individuals lacking a copy of the GHRd3 allele. Weak associations with GHR genotype were also noted for peripheral systolic and diastolic blood pressure in hypertensive patients. Although the underlying mechanisms are still unclear, our findings are consistent with a complex relationship between height, hypertension, GH1 promoter haplotype, GHR polymorphism and the risk of stroke. 相似文献
996.
997.
Shaobai Huang Nicolas L. Taylor Reena Narsai Holger Eubel James Whelan A. Harvey Millar 《Plant molecular biology》2010,72(3):331-342
Complex II plays a central role in mitochondrial metabolism as a component of both the electron transport chain and the tricarboxylic
acid cycle. However, the composition and function of the plant enzyme has been elusive and differs from the well-characterised
enzymes in mammals and bacteria. Herewith, we demonstrate that mitochondrial Complex II from Arabidopsis and rice differ significantly
in several aspects: (1) Stability—Rice complex II in contrast to Arabidopsis is not stable when resolved by native electrophoresis
and activity staining. (2) Composition—Arabidopsis complex II contains 8 subunits, only 7 of which have homologs in the rice
genome. SDH 1 and 2 subunits display high levels of amino acid identity between two species, while the remainder of the subunits
are not well conserved at a sequence level, indicating significant divergence. (3) Gene expression—the pairs of orthologous
SDH1 and SDH2 subunits were universally expressed in both Arabidopsis and rice. The very divergent genes for SDH3 and SDH4 were co-expressed in both species, consistent with their functional co-ordination to form the membrane anchor. The plant-specific
SDH5, 6 and 7 subunits with unknown functions appeared to be differentially expressed in both species. (4) Biochemical regulation -succinate-dependent
O2 consumption and SDH activity of isolated Arabidopsis mitochondria were substantially stimulated by ATP, but a much more minor
effect of ATP was observed for the rice enzyme. The ATP activation of succinate-dependent reduction of DCPIP in frozen-thawed
and digitonin-solubilised mitochondrial samples, and with or without the uncoupler CCCP, indicate that the differential ATP
effect on SDH is not via the protonmotive force but likely due to an allosteric effect on the plant SDH enzyme itself, in
contrast to the enzyme in other organisms. 相似文献
998.
999.
1000.
Malate oxidation by plant mitochondria enables the generation of both oxaloacetate and pyruvate for tricarboxylic acid (TCA) cycle function, potentially eliminating the need for pyruvate transport into mitochondria in plants. Here, we show that the absence of the mitochondrial pyruvate carrier 1 (MPC1) causes the co-commitment loss of its putative orthologs, MPC3/MPC4, and eliminates pyruvate transport into Arabidopsis thaliana mitochondria, proving it is essential for MPC complex function. While the loss of either MPC or mitochondrial pyruvate-generating NAD-malic enzyme (NAD-ME) did not cause vegetative phenotypes, the lack of both reduced plant growth and caused an increase in cellular pyruvate levels, indicating a block in respiratory metabolism, and elevated the levels of branched-chain amino acids at night, a sign of alterative substrate provision for respiration. 13C-pyruvate feeding of leaves lacking MPC showed metabolic homeostasis was largely maintained except for alanine and glutamate, indicating that transamination contributes to the restoration of the metabolic network to an operating equilibrium by delivering pyruvate independently of MPC into the matrix. Inhibition of alanine aminotransferases when MPC1 is absent resulted in extremely retarded phenotypes in Arabidopsis, suggesting all pyruvate-supplying enzymes work synergistically to support the TCA cycle for sustained plant growth.Pyruvate is supplied by three independent processes that act synergistically to maintain metabolic flux and support plant respiration in a variety of circumstances. 相似文献