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Long terminal repeat (LTR) retrotransposons, mobile genetic elements comprising substantial proportions of many eukaryotic
genomes, are so named for the presence of LTRs, direct repeats about 250–600 bp in length flanking the open reading frames
that encode the retrotransposon enzymes and structural proteins. LTRs include promotor functions as well as other roles in
retrotransposition. LTR retrotransposons, including the Gypsy-like Boudicca and the Pao/BEL-like Sinbad elements, comprise a substantial proportion of the genome of the human blood fluke, Schistosoma mansoni. In order to deduce the capability of specific copies of Boudicca and Sinbad LTRs to function as promotors, these LTRs were investigated analytically and experimentally. Sequence analysis revealed the
presence of TATA boxes, canonical polyadenylation signals, and direct inverted repeats within the LTRs of both the Boudicca and Sinbad retrotransposons. Inserted in the reporter plasmid pGL3, the LTR of Sinbad drove firefly luciferase activity in HeLa cells in its forward and inverted orientation. In contrast, the LTR of Boudicca did not drive luciferase activity in HeLa cells. The ability of the Sinbad LTR to transcribe in both its forward and inverted orientation represents one of few documented examples of bidirectional
promotor function. 相似文献
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Salazar M González E Casaretto JA Casacuberta JM Ruiz-Lara S 《Plant cell reports》2007,26(10):1861-1868
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Background
Gonadotropin releasing hormone (GnRH) is responsible for stimulation of gonadotropic hormone (GtH) in the hypothalamus-pituitary-gonadal axis (HPG). The regulatory mechanisms responsible for brain specificity make the promoter attractive for in silico analysis and reporter gene studies in zebrafish (Danio rerio).Results
We have characterized a zebrafish [Trp7, Leu8] or salmon (s) GnRH variant, gnrh 3. The gene includes a 1.6 Kb upstream regulatory region and displays the conserved structure of 4 exons and 3 introns, as seen in other species. An in silico defined enhancer at -976 in the zebrafish promoter, containing adjacent binding sites for Oct-1, CREB and Sp1, was predicted in 2 mammalian and 5 teleost GnRH promoters. Reporter gene studies confirmed the importance of this enhancer for cell specific expression in zebrafish. Interestingly the promoter of human GnRH-I, known as mammalian GnRH (mGnRH), was shown capable of driving cell specific reporter gene expression in transgenic zebrafish.Conclusions
The characterized zebrafish Gnrh3 decapeptide exhibits complete homology to the Atlantic salmon (Salmo salar) GnRH-III variant. In silico analysis of mammalian and teleost GnRH promoters revealed a conserved enhancer possessing binding sites for Oct-1, CREB and Sp1. Transgenic and transient reporter gene expression in zebrafish larvae, confirmed the importance of the in silico defined zebrafish enhancer at -976. The capability of the human GnRH-I promoter of directing cell specific reporter gene expression in zebrafish supports orthology between GnRH-I and GnRH-III.8.
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Andrey Anisimov Kimmo Koivu Anne Kanerva Seppo Kaijalainen Kari Juntunen Viktor Kuvshinov 《Molecular breeding : new strategies in plant improvement》2007,19(3):241-253
The aim of our study was to identify the highest expressing rubisco small subunit (RbcS) promoters (pRbcS) from the cotyledons of germinating seedlings of Brassica rapa var. oleifera to drive high-level and preferably stage-specific transgenic protein expression in Brassicaceae plants. We cloned four new
pRbcS promoters using several approaches, including the construction of a cDNA library and use of genome walking technique. Real-time
PCR analysis of RbcS mRNA expression clearly showed that two of these promoters exhibited the highest activity on the germination stage of plant
development. We used gusA expression as a reporter of promoter activity in Brassica napus and Nicotiana tabacum plants that were transformed with the constructs using an Agrobacterium-mediated transformation strategy. The mRNA level
of RbcS and of gusA was quantified in transformed plants. The data obtained demonstrate that the promoter most active in seedlings under native
conditions was also most active in transgenic constructs at the same stage of plant development. The fine structure of the
promoters is discussed herein. 相似文献
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We describe a newRenilla reniformis luciferase reporter gene,RiLUC, which was designed to allow detection of luciferase activity in studies involvingAgrobacterium-based transient expression studies. TheRLUC gene was altered to contain a modified intron from the castor bean catalase gene while maintaining consensus eukaryotic splicing
sites recognized by the plant spliceosome.RLUC andRiLUC reporter genes were fused to the synthetic plant SUPER promoter. Luciferase activity within agrobacteria containing the SUPER-RLUC construct increased during growth in culture. In contrast, agrobacteria harboring the SUPER-RiLUC gene fusion showed no detectable luciferase activity. Agrobacteria containing these gene fusions were cotransformed with
a compatible normalization plasmid containing a cauliflower mosaic virus 35S promoter (CaMV) joined to the firefly luciferase
coding region (FiLUC) and infused into tobacco leaf tissues through stomatal openings. The kinetics of luciferase production from theRLUC orRiLUC reporters were consistent, with expression of theRiLUC gene being limited to transiently transformed plant cells.RiLUC activity from the reporter gene fusions was measured transiently and within stably transformed tobacco leaf tissues. Analysis
of stably transformed tobacco plants harboring either reporter gene fusion showed that the intron altered neither the levels
of luciferase activity nor tissue-specific expression patterns driven by the SUPER promoter. These results demonstrate that
theRiLUC reporter gene can be used to monitor luciferase expression in transient and stable transformation experiments without interference
from contaminating agrobacteria. 相似文献
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A genetic transformation system has been developed for selected embryogenic cell lines of hybrids Abies alba × A. cephalonica (cell lines AC2, AC78) and Abies alba × A. numidica (cell line AN72) using Agrobacterium tumefaciens. The cell lines were derived from immature or mature zygotic embryos on DCR medium containing BA (1 mg l−1). The T-DNA of plant transformation vector contained the β-glucuronidase reporter gene under the control of double dCaMV 35S promoter and the neomycin phosphotransferase selection marker gene driven by the nos promoter. The regeneration of putative transformed tissues started approximately 1 week after transfer to the selection medium
containing 10 mg geneticin l−1. GUS activity was detected in most of the geneticin-resistant sub-lines AN72, AC2 and AC78, and the transgenic nature of
embryogenic cell lines was confirmed by PCR approach. Plantlet regeneration from PCR-positive embryogenic tissues has been
obtained as well. The presence of both gus and nptII genes was confirmed in 11 out of 36 analysed emblings. 相似文献
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Xiaoping Chen Zhangying Wang Jianhua Wang Maoyan Wang Li Zhao Guoying Wang 《Plant Cell, Tissue and Organ Culture》2007,88(1):11-20
ADP-glucose pyrophosphorylase (AGPase) represents a key regulatory step in starch synthesis. A 0.9 kb of 5′ flanking region
preceding Brittle2 gene, encoding the small subunit of maize endosperm AGPase, was cloned from maize genome and its expression pattern was studied
via the expression of β-glucuronidase (GUS) gene in transgenic tobacco. Analysis of GUS activities showed that the 0.9 kb
fragment flanking Brittle2 gene was sufficient for driving the seed-preferred expression of the reporter gene. The activity of the 0.9 kb 5′ flanking
fragment was compared with that of the tandem promoter region from a zein gene (zE19, encoding a maize 19 kDa zein protein). The results indicated that both promoters were seed-preferred in a dicotyledonous
system as tobacco and the activity of zE19 promoter was three to fourfold higher than that of the 0.9 kb fragment flanking Brittle2 gene in transgenic tobacco seeds. At the same time, zE19-driven GUS gene expressed earlier than Brittle2 promoter during seed development. Histochemical location of GUS activity indicated that both promoters showed high expression
in embryos, which is different from similar promoters tested in maize. 相似文献