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Synek L Schlager N Eliás M Quentin M Hauser MT Zárský V 《The Plant journal : for cell and molecular biology》2006,48(1):54-72
The exocyst is a hetero-oligomeric protein complex involved in exocytosis and has been extensively studied in yeast and animal cells. Evidence is now accumulating that the exocyst is also present in plants. Bioinformatic analysis of genes encoding plant homologs of the exocyst subunit, Exo70, revealed that three Exo70 subgroups are evolutionarily conserved among angiosperms, lycophytes and mosses. Arabidopsis and rice contain 22 and approximately 39 EXO70 genes, respectively, which can be classified into nine clusters considered to be ancient in angiosperms (one has been lost in Arabidopsis). We characterized two independent T-DNA insertional mutants of the AtEXO70A1 gene (exo70A1-1 and exo70A1-2). Heterozygous EXO70A1/exo70A1 plants appear to be normal and segregate in a 1:2:1 ratio, suggesting that neither male nor female gametophytes are affected by the EXO70A1 disruption. However, both exo70A1-1 and exo70A1-2 homozygotes exhibit an array of phenotypic defects. The polar growth of root hairs and stigmatic papillae is disturbed. Organs are generally smaller, plants show a loss of apical dominance and indeterminate growth where instead of floral meristems new lateral inflorescences are initiated in a reiterative manner. Both exo70A1 mutants have dramatically reduced fertility. These results suggest that the putative exocyst subunit EXO70A1 is involved in cell and organ morphogenesis. 相似文献
874.
Comparisons of morphology, nuclear gene sequencing and microsatellites were used to identify 19 hybrids between the related species Cottus poecilopus and Cottus gobio in three rivers of the Odra River drainage basin. All hybrids were the results of backcrossing and no F1 generation hybrid was found. The resulting progeny are fertile and continue in backcrossing with parental conspecifics. A high representation of backcrosses appears to indicate a lack of reproduction barriers within the hybridization process. It was impossible to differentiate individual back-cross categories on the sole basis of six loci. Mitochondrial haplotypes indicate that this is not a one-way process. In our study, hybridization was asymmetrical in favour of Cottus poecilopus. 相似文献
875.
A Trostchansky C Batthyány H Botti R Radi A Denicola H Rubbo 《Archives of biochemistry and biophysics》2001,395(2):225-232
Peroxynitrite (PN), the product of the diffusion-limited reaction between nitric oxide (*NO) and superoxide (O*-(2)), represents a relevant mediator of oxidative modifications in low-density lipoprotein (LDL). This work shows for the first time the simultaneous action of low-controlled fluxes of PN and *NO on LDL oxidation in terms of lipid and protein modifications as well as oxidized lipid-protein adduct formation. Fluxes of PN (e.g., 1 microM min(-1)) initiated lipid oxidation in LDL as measured by conjugated dienes and cholesteryl ester hydroperoxides formation. Oxidized-LDL exhibited a characteristic fluorescent emission spectra (lambda(exc) = 365 nm, lambda(max) = 417 nm) in parallel with changes in both the free amino groups content and the relative electrophoretic mobility of the particle. Physiologically relevant fluxes of *NO (80-300 nM min(-1)) potently inhibited these PN-dependent oxidative processes. These results are consistent with PN-induced adduct formation between lipid oxidation products and free amino groups of LDL in a process prevented by the simultaneous presence of *NO. The balance between rates of PN and *NO production in the vascular wall will critically determine the final extent of LDL oxidative modifications leading or not to scavenger receptor-mediated LDL uptake and foam cell formation. 相似文献
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J. Štěpánek Jozef Kowalewski J. Lang Peter Mojzeš 《Journal of biological inorganic chemistry》1998,3(5):543-556
The interaction of Ni(II) ions with adenine mononucleotides (5′-AMP, 3′-AMP, 2′-AMP, 2′,3′-cAMP, 3′,5′-cAMP) was studied
in aqueous solution using Raman spectroscopy and 13C and 31P NMR paramagnetic relaxation measurements. Macrochelate structures were observed to form for all non-cyclic AMPs, with increasing
stability in the series: 3′-AMP < 2′-AMP < 5′-AMP. N7 of adenine was found to be the key site of the Ni(II)-adenine interaction
for all non-cyclic AMPs. For 2′-AMP, an alternative binding to the pyrimidine ring may also exist. The dependence of Raman
spectra on AMP and Ni(II) concentration confirmed the existence of a stable 1 : 2 Ni(II)-(5′-AMP) complex, besides the 1 : 1
complexes. In this complex, the adenine moieties of both 5′-AMP molecules are situated close to Ni(II), and their relative
orientations with respect to the cation are very similar. The paramagnetic relaxation enhancements of the carbons indicate
that the nickel ion is not located in the plane of the adenine units, but that the line connecting Ni(II) and N7 deviates
strongly from the adenine planes. Phosphates are outer-sphere coordinated by the cation. Findings from both methods have led
us to propose possible global architectures of the complex.
Received: 26 June 1998 / Accepted: 22 July 1998 相似文献
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