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  • 1
    Electronic Resource
    Electronic Resource
    An ABA-responsive bZIP protein, OsBZ8, mediates sugar repression of α-amylase gene expression (2003)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 119 (2003), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Expression of some α-amylase genes in cereals is suppressed by sugars and activated by sugar starvation. A 100-bp sugar response sequence (SRS) identified in the promoter of a rice α-amylase gene, αAmy3, contains three essential motifs: the GC box, the G box, and the TATCCA element. To study the mechanism of sugar regulation of αAmy3 transcription, an ABA-responsive bZIP protein, OsBZ8, which binds specifically to the G box in αAmy3 SRS was characterized and function analysed. In sucrose-starved rice suspension cells and embryos, decline in OsBZ8 mRNA levels coincided with the induction of αAmy3 mRNA accumulation. In vivo gain- and loss-of-function studies by transient expression assays in rice embryos revealed that OsBZ8 suppresses SRS activity through the G box and overrides the activity of an activator, OsMYBS1, which binds to the TATCCA element. Gel mobility shift assays revealed that OsBZ8 binds specifically to the G box in vitro. These studies suggest that OsBZ8 is a suppressor responsible for sugar repression of αAmy3 expression, and OsMYBS1 is responsible for sugar starvation induced expression of αAmy3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2003.00159.x
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  • 2
    Electronic Resource
    Electronic Resource
    Sugars act as signal molecules and osmotica to regulate the expression of α-amylase genes and metabolic activities in germinating cereal grains (1996)
    Springer
    Plant molecular biology 30 (1996), S. 1277-1289 
    Details
    ISSN: 1573-5028
    Keywords: α-amylase gene ; metabolic control ; osmotic control ; feedback control ; rice ; sugar signal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The molecular mechanisms that initiate and control the metabolic activities of seed germination are largely unknown. Sugars may play important roles in regulating such metabolic activities in addition to providing an essential carbon source for the growth of young seedlings and maintaining turgor pressure for the expansion of tissues during germination. To test this hypothesis, we investigated the physiological role of sugars in the regulation of α-amylase gene expression and carbohydrate metabolism in embryo and endosperm of germinating rice seeds. RNA gel blot analysis revealed that in the embryo and aleurone cells, expression of four α-amylase genes was differentially regulated by sugars via mechanisms beyond the well-known hormonal control mechanism. In the aleurone cells, expression of these α-amylase genes was regulated by gibberellins produced in the embryo and by osmotically active sugars. In the embryo, expression of two α-amylase genes and production of gibberellins were transient, and were probably induced by depletion of sugars in the embryo upon imbibition, and suppressed by sugars influx from the endosperm as germination proceeded. The differential expression of the four α-amylase genes in the embryo and aleurone cells was probably due to their markedly different sensitivities to changes in tissue sugar levels. Our study supports a model in which sugars regulate the expression of α-amylase genes in a tissue-specific manner: via a feedback control mechanism in the embryo and via an osmotic control mechanism in the aleurone cells. An interactive loop among sugars, gibberellins, and α-amylase genes in the germinating cereal grain is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019558
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  • 3
    Electronic Resource
    Electronic Resource
    Agrobacterium-mediated production of transgenic rice plants expressing a chimeric α-amylase promoter/β-glucuronidase gene (1993)
    Springer
    Plant molecular biology 22 (1993), S. 491-506 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; α-amylase promoter ; α-glucuronidase ; Oryza sativa ; potato suspension culture ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have successfully transferred and expressed a reporter gene driven by an α-amylase promoter in a japonica type of rice (Oryza sativa L. cv. Tainung 62) using the Agrobacterium-mediated gene transfer system. Immature rice embryos (10–12 days after anthesis) were infected with an Agrobacterium strain carrying a plasmid containing chimeric genes of β-glucuronidase (uidA) and neomycin phosphotransferase (nptII). Co-incubation of potato suspension culture (PSC) with the Agrobacterium inoculum significantly improved the transformation efficiency of rice. The uidA and nptII genes, which are under the control of promoters of a rice α-amylase gene (αAmy8) and Agrobacterium nopaline synthase gene (nos), respectively, were both expressed in G418-resistant calli and transgenic plants. Integration of foreign genes into the genomes of transgenic plants was confirmed by Southern blot analysis. Histochemical localization of GUS activity in one transgenic plant (R0) revealed that the rice α-amylase promoter functions in all cell types of the mature leaves, stems, sheaths and roots, but not in the very young leaves. This transgenic plant grew more slowly and produced less seeds than the wild-type plant, but its R1 and R2 progenies grew normally and produced as much seeds as the wild-type plant. Inheritance of foreign genes to the progenies was also confirmed by Southern blot analysis. These data demonstrate successful gene transfer and sexual inheritance of the chimeric genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015978
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  • 4
    Electronic Resource
    Electronic Resource
    Regulation and evolution of the single alpha-tubulin gene of the ciliate Tetrahymena thermophila (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 27 (1994), S. 272-283 
    Details
    ISSN: 0886-1544
    Keywords: cell cycle ; transcription ; mRNA decay ; autoregulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The single alpha-tubulin gene of Tetrahymena thermophila was isolated from a genomic library and shown to encode a single protein. Comparisons of the rates of evolution of this gene with other alpha-tubulin sequences revealed that it belongs to a group of more evolutionarily constrained alpha-tubulin proteins in animals, plants, and protozoans versus the group of more rapidly evolving fungal and variant animal alpha-tubulins. The single alpha-tubulin of Tetrahymena must be used in a variety of microtubule structures, and we suggest that equivalently conserved alpha-tubulins in other organisms are evolutionarily constrained because they, too, are multifunctional. Reduced constraints on fungal tubulins are consistent with their simpler microtubule systems. The animal variant alpha-tubulins may also have diverged because of fewer functional requirements or they could be examples of specialized tubulins. To analyze the role of tubulin gene expression in regulation of the complex microtubule system of Tetrahymena, alpha-tubulin mRNA amounts were examined in a number of cell states. Message levels increased in growing versus starved cells and also during early stages of conjugation. These changes were correlated with increases in transcription rates. Additionally, alpha-tubulin mRNA levels oscillate in a cell cycle dependent fashion caused by changes in both transcription and decay rates. Therefore, as in other organisms, Tetrahymena adjusts alpha-tubulin message amounts via message decay. However the complex control of alpha-tubulin mRNA during the Tetrahymena life cycle involves regulation of both decay and transcription rates. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970270308
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  • 5
    Electronic Resource
    Electronic Resource
    An efficient protocol for sugarcane (Saccharum spp. L.) transformation mediated by Agrobacterium tumefaciens (1998)
    Springer
    Transgenic research 7 (1998), S. 213-222 
    Details
    ISSN: 1573-9368
    Keywords: Saccharum ; Agrobacterium ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This is the first successful report of the recovery of morphologically normal transgenic sugarcane plants from co-cultivation of calluses with Agrobacterium tumefaciens. Transformation frequencies (total of transgenic plants/number of cell clusters) were between 9.4 × 10−3 and 1.15 × 10−2. In our experiments, both LBA4404 (pTOK233) and EHA101 (pMTCA3IG), carrying a super-binary vector or supervirulent strain, respectively, were successful for sugarcane transformation. We found that three main factors: (1) the use of young regenerable calluses as target explants; (2) induction and/or improvement of the A. tumefaciens virulence system with sugarcane cell cultures and (3) pre-induction of organogenesis or somatic-embryogenesis-like sexual embryos, seem to be crucial in order to increase the cells competence for T-DNA transfer process. Patterns generated by Southern hybridization confirmed that T-DNAs were randomly integrated into sugarcane genome without th e persistence of A. tumefaciens in the transgenic plants
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008845114531
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