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52.
Changing concepts in plant hormone action 总被引:4,自引:0,他引:4
Th.?GasparEmail author C.?Kevers O.?Faivre-Rampant M.?Crèvecoeur CL.?Penel H.?Greppin J.?Dommes 《In vitro cellular & developmental biology. Plant》2003,39(2):85-106
Summary A plant hormone is not, in the classic animal sense, a chemical synthesized in one organ, transported to a second organ to
exert a chemical action to control a physiological event. Any phytohormone can be synthesized everywhere and can influence
different growth and development processes at different places. The concept of physiological activity under hormonal control
cannot be dissociated from changes in concentrations at the site of action, from spatial differences and changes in the tissue's
sensitivity to the compound, from its transport and its metabolism, from balances and interactions with the other phytohormones,
or in their metabolic relationships, and in their signaling pathways as well. Secondary messengers are also involved. Hormonal
involvement in physiological processes can appear through several distinct manifestations (as environmental sensors, homeostatic
regulators and spatio-temporal synchronizers, resource allocators, biotime adjusters, etc.), dependent on or integrated with
the primary biochemical pathways. The time has also passed for the hypothesized ‘specific’ developmental hormones, rhizocaline,
canlocaline, and florigen: root, stem, and flower formation result from a sequential control of specific events at the right
places through a coordinated control by electrical signals, the known phytohormones and nonspecific molecules of primary and
secondary metabolism, and involve both cytoplasmic and apoplastic compartments. These contemporary views are examined in this
review. 相似文献
53.
Bell RP Verdijk D Relou M Smith D Regeling H Ebbers EJ Leemhuis FM Oniciu DC Cramer CT Goetz B Pape ME Krause BR Bisgaier CL Dasseux JL 《Bioorganic & medicinal chemistry》2005,13(1):223-236
A series of cycloalkyl-substituted oxo-alkanedicarboxylic acids have been prepared by the TosMIC methodology departing from haloalkyl-substituted cycloalkylcarboxylic esters. cyclopropyl derivatives showed IC(50) activity in the 0.3-1.0 microM range on the de novo incorporation of radiolabeled acetate into lipids in primary cultures of rat hepatocytes, and they showed lipid-regulating properties when tested in vivo in female obese Zucker fatty rats. 相似文献
54.
A sensitive and rapid immunological detection method was used to screen for apolipoprotein A-IV variants. Antibodies to human lymph chylomicron or plasma apolipoprotein A-IV, and plasma apolipoprotein A-I were raised in rabbits. Antibodies to apolipoprotein A-I or apolipoprotein A-IV were shown to be monospecific to their respective antigens by reactivity against human chylomicron apolipoproteins by immunoblot analysis. Plasma samples were obtained from dyslipidemic subjects from the Lipid Research Clinic of Columbia University. The plasma samples were isoelectrically focused (pH 4-6) on slab gels. Plasma proteins were then transferred to nitrocellulose paper for immunoblotting. Apolipoprotein A-IV polymorphism was determined by specific immunological detection of apolipoprotein A-IV. Identical apolipoprotein A-IV isoprotein patterns were observed when either antibodies to lymph or plasma apolipoprotein A-IV were used for immunoblotting. All the dyslipidemic plasma samples screened contained the two major and one or two minor isoproteins of normal plasma. In two instances, new apolipoprotein A-IV variants having an additional isoform were detected. One subject was hypertriglyceridemic (triacylglycerols = 342 mg/dl, cholesterol = 251 mg/dl) and had an additional major acidic apolipoprotein A-IV isoform. Another subject with mild hypocholesterolemia (triacylglycerols = 209 mg/dl, cholesterol = 120 mg/dl) was found to have additional major and minor basic apolipoprotein A-IV isoforms. The specificity of this technique allows detection of polymorphism of apolipoproteins of similar isoelectric points by use of a single dimension isoelectric focusing gel. This technique also demonstrated the presence of altered apolipoprotein A-I isoforms in the plasma of a patient with Tangier disease. These isoforms were previously identified as isoforms 2 and 4 of normal plasma by use of two-dimensional gel electrophoresis. However, by use of this new technique and careful evaluation of previously published two-dimensional gels, we now identify these apolipoprotein A-I isoforms as being more acidic than those of normal plasma. 相似文献
55.
A statistical analysis of the nucleotide sequence variability in 14
published hepatitis B virus (HBV) genomes was carried out using parametric
and nonparametric methods. A parametric statistical model revealed that the
different regions of the genome differed significantly in their
variability. The conclusion was supported by a nonparametric kernel-density
model of the HBV genome. Genes S, C, and P, region X, the precore region,
and the pre-S2/pre-S1 regions were ranked in order of increasing
variability. In many instances, conserved regions of the genome identified
with sequences of known function in HBV biology. However, other
characterized regions (such as pre-S) showed much variability despite the
involvement of their encoded peptides in specific functions. Point
mutations that may result in the formation of stop codons and amino acid
changes may affect the clinical picture of HBV infection and may be
reflected in atypical serological patterns.
相似文献
56.
Sequence, organization, and evolution of the A+T region of Drosophila melanogaster mitochondrial DNA 总被引:2,自引:0,他引:2
The long (4.6-kb) A+T region of Drosophila melanogaster mitochondrial DNA
has been cloned and sequenced. The A+T region is organized in two large
arrays of tandemly repeated DNA sequence elements, with nonrepetitive
intervening and flanking sequences comprising only 22% of its length. The
first repeat array consists of five repeats of 338-373 bp. The second
consists of four intact 464-bp repeats and a fifth partial repeat of 137
bp. Three DNA sequence elements are found to be highly conserved in D.
melanogaster and in several Drosophila species with short A+T regions.
These include a 300-bp DNA sequence element that overlaps the DNA
replication origin and two thymidylate stretches identified on opposite DNA
strands. We conclude that the length heterogeneity observed in the A+T
regulatory region in mitochondrial DNAs from the genus Drosophila results
from the expansion (and contraction) of the number of repeated DNA sequence
elements. We also propose that the 300-bp conserved DNA sequence element,
in conjunction with another primary sequence determinant, perhaps the
adjacent thymidylate stretch, functions in the regulation of mitochondrial
DNA replication.
相似文献
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SGO1 but not SGO2 is required for maintenance of centromere cohesion in Arabidopsis thaliana meiosis
L. Zamariola N. De Storme CL. Tiang S. J. Armstrong F. C. H. Franklin D. Geelen 《Sexual plant reproduction》2013,26(3):197-208
Shugoshin is a protein conserved in eukaryotes and protects sister chromatid cohesion at centromeres in meiosis. In our study, we identified the homologs of SGO1 and SGO2 in Arabidopsis thaliana. We show that AtSGO1 is necessary for the maintenance of centromere cohesion in meiosis I since atsgo1 mutants display premature separation of sister chromatids starting from anaphase I. Furthermore, we show that the localization of the specific centromeric cohesin AtSYN1 is not affected in atsgo1, suggesting that SGO1 centromere cohesion maintenance is not mediated by protection of SYN1 from cleavage. Finally, we show that AtSGO2 is dispensable for both meiotic and mitotic cell progression in Arabidopsis. 相似文献
60.
Dott. CL. CH. Mathon 《Plant biosystems》2013,147(2-3):345-356
Resumé Chez les Blés branchus de l'espèce «turgidum» (Triticum turgidum compositum), il existe des sortes à thermostade plutôt froid (Blés d'hiver ou de semi-hiver) et des sortes à thermostade chaud, tièe ou «indifférent» (Blés de printemps). Les Blés branchus de l'espèce «turgidum» apparaissent comme étant des plantes à photostade de jour long. La plus ou moins grande rapidité de l'accomplissement du photostade, par rapport à la rapidité de l'assimilation des matières plastiques, détermine la structure, — non ramifiée ou ramifiée — de l'épi. 相似文献