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81.
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
82.
Cell suspension cultures are useful for a wide range of biochemical and physiological studies, yet their production can be
technically demanding and often unreliable. Here we describe a protocol for producing Arabidopsis cell suspension cultures
that is reliable and easy to use. 相似文献
83.
Adenovirus early region 4 encodes functions required for efficient DNA replication, late gene expression, and host cell shutoff. 总被引:72,自引:51,他引:21 下载免费PDF全文
To delineate the function of adenovirus early region 4 (E4) gene products, we constructed a set of mutant viruses which carry defined lesions within this coding region. Deletion and insertion mutations within six of seven known E4 coding regions had no measurable effect on virus growth in cultured cells. A variant carrying a deletion within the last coding region (encoding a 34,000-molecular-weight polypeptide) was modestly defective, and a mutant lacking the majority of the E4 region was severely defective for growth. The phenotypes of the two defective mutants are similar and complex. Both display perturbations in DNA replication, translation of the E2A mRNA, accumulation of late viral mRNAs, and host cell shutoff. 相似文献
84.
Identification of the E5 open reading frame of human papillomavirus type 16. 总被引:10,自引:7,他引:3 下载免费PDF全文
Sequencing of the E5 open reading frame (ORF) of human papillomavirus type 16 revealed an additional nucleotide, a thymidine residue, at position 3903 compared with the original sequence (Seedorf et al., Virology 145:181-185, 1985). The additional T had two effects; first, in reading frame 2, in which the original E5 ORF was predicted, the additional T changed the reading frame downstream of position 3903 to create an ORF, which we designated E5, that terminated at position 4018 and potentially encoded a 52-amino-acid polypeptide. Secondly, in reading frame 3, a new ORF was created (positions 3807 to 4097), which we propose is the authentic papillomavirus type 16 E5 ORF. It contained a methionine residue and encoded an additional 82 amino acids. Both ORFs have been cloned into bacterial expression vectors (pATH), and the fusion proteins have been used to generate polyclonal antibodies in rabbits. 相似文献
85.
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
86.
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
87.
Somaclonal variation in the progeny of transgenic barley 总被引:13,自引:0,他引:13
P. Bregitzer S. E. Halbert P. G. Lemaux 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(3-4):421-425
Somaclonal variation (SCV) in transgenic plants may slow the incorporation of introduced genes into commercially competitive
cultivars. Somaclonal variation in transgenic barley (Hordeum vulgare L.) was assessed in one experiment by comparing the agronomic characteristics of 44 segregating transgenic lines in the T2 generation to their non-transformed parent (‘Golden Promise’). A second experiment examined the agronomic characteristics
of seven transgenic-derived, null (non-transgenic) segregant lines in the T2 and T4 generations. Compared to their uncultured parent, Golden Promise, most of these lines were shorter, lower yielding, and had
smaller seed, and the variability among individual plants was higher. The frequency and severity of the observed SCV was unexpectedly
high, and the transformation procedure appeared to induce greater SCV than tissue culture in the absence of transformation.
Attempts to understand the sources of SCV, and to modify transformation procedures to reduce the generation of SCV, should
be made.
Received: 26 June 1997 / Accepted: 31 October 1997 相似文献
88.
The E7 gene of human papillomavirus type 16 is sufficient for immortalization of human epithelial cells. 总被引:49,自引:23,他引:26 下载免费PDF全文
The contribution of the E6 and E7 open reading frames of human papillomavirus type 6b (HPV6b) and HPV16 to immortalization of human keratinocytes was evaluated by using amphotropic recombinant retroviruses. The HPV16 E7 gene could immortalize primary human keratinocytes without the cooperation of the viral E6 gene; however, E6 was able to contribute significantly to the efficiency of the E7 immortalizing function. Infection of HFE cells with retroviruses carrying the 16E6, 6bE6, or 6bE6E7 open reading frame did not result in immortalization. 相似文献
89.
David R. Halbert Laurence M. Demers John Fontana D.E. Darnell Jones 《Prostaglandins & other lipid mediators》1975,10(6):1047-1056
A patient with functional primary dysmenorrhea of over two years duration was subjected to the endometrial jet wash technique during the period of active menstrual flow. Prostaglandin F analysis of the jet washings revealed significantly elevated levels during menstruation over normal control levels. Following indomethacin therapy, jet wash prostaglandin F levels were dramatically reduced and the patient became asymptomatic. A cause and effect relationship between prostaglandin F and dysmenorrhea is suggested by these studies 相似文献
90.
Adeno-associated virus vectors transduce primary cells much less efficiently than immortalized cells. 总被引:16,自引:11,他引:5 下载免费PDF全文
Immortalized cell lines have been used to study infection and replication of adeno-associated virus (AAV) in culture, but primary cells presumably provide a better model for AAV behavior in animals. Here, we have evaluated the ability of AAV vectors to transduce primary and immortalized strains of human epithelial cells and fibroblasts. Two AAV vectors were used, one that transduced an alkaline phosphatase gene (AAV-LAPSN), and one that transduced a beta-galactosidase/neomycin phosphotransferase fusion gene (AAV-L beta geo). The transduction efficiency of the AAV-LAPSN vector, quantitated by measurement of alkaline phosphatase-positive cell foci following infection, was 10 to 60 times greater in immortalized human cells than in primary cells, and total alkaline phosphatase activity in cell lysates was 40 to 50 times greater in immortalized cells. The AAV-L beta geo vector gave similar results. In contrast, the transduction efficiency of a retrovirus vector encoding alkaline phosphatase was equivalent in primary and immortalized cells. Analysis of the quantity and state of the AAV vector genomes in cells showed that primary and immortalized cells contained comparable numbers of vector copies per cell and that the vast majority of vector DNA was not integrated into the cell genome. Additionally, the level of AAV vector-derived message paralleled the transduction efficiency. These results indicate that the block to functional transduction in primary cells occurred after virus entry and limited the abundance of vector-derived message. Data from AAV transduction in cultures of human cells containing immortalizing genes suggest that cellular changes secondary to the introduction of immortalizing genes increased permissiveness for transduction by AAV vectors. In summary, our data demonstrate that AAV vectors transduce primary human cells much less efficiently than immortalized cells and indicate the importance of using primary cells to evaluate AAV vectors for gene therapy applications. 相似文献