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  • 1985-1989  (8)
  • Genetics  (4)
  • Agrobacterium tumefaciens  (2)
  • hepatic encephalopathy  (2)
  • 1
    Electronic Resource
    Electronic Resource
    T-DNA structure and gene expression in petunia plants transformed by Agrobacterium tumefaciens C58 derivatives (1987)
    Springer
    Molecular genetics and genomics 207 (1987), S. 478-485 
    Details
    ISSN: 1617-4623
    Keywords: Agrobacterium tumefaciens ; Transgenic plants ; T-DNA structure ; Between-transformant variability ; Chimeric genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously described substantial variation in the level of expression of two linked genes which were introduced into transgenic petunia plants using Agrobacterium tumefaciens. These genes were (i) nopaline synthase (nos) and (ii) a chimeric chlorophyll a/b binding protein/octopine synthase (cab/ocs) gene. In this report we analyze the relationship between the level of expression of the introduced genes and T-DNA structure and copy number in 40 transgenic petunia plants derived from 26 transformed calli. Multiple shoots were regenerated from 8 of these calli and in only 6 cases were multiple regenerated shoots from each callus genotypically identical to each other. Many genotypes showed no nos gene expression (22/28). Most of the plants (16/22) which lacked nos gene expression did contain nos-encoding DNA with the expected restriction enzyme map. Similarly, amongst the genotypes showing no cab/ocs gene expression, the majority (11/28) did not show any alterations in restriction fragments corresponding to the expected cab/ocs coding sequences (10/11). Approximately half of the plants carried multiple copies of T-DNA in inverted repeats about the left or right T-DNA boundaries. No positive correlation was observed between the copy number of the introduced DNA and the level of expression of the introduced genes. However, plants with high copy number complex insertions composed of multiple inverted repeats in linear arrays usually showed low levels of expression of the introduced genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331618
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  • 2
    Electronic Resource
    Electronic Resource
    Locations and stability of Agrobacterium-mediated T-DNA insertions in the Lycopersicon genome (1986)
    Springer
    Molecular genetics and genomics 204 (1986), S. 64-69 
    Details
    ISSN: 1617-4623
    Keywords: Agrobacterium tumefaciens ; Genetic stability ; Linkage analysis ; Molecular markers ; Tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genomic distribution and genetic behavior of DNA sequences introduced into the tomato genome by Agrobacterium tumefaciens were investigated in the backcross progeny of 10 transformed Lycopersicon esculentum x L. pennellii hybrids. All transformants were found to represent single locus insertions based on the co-segregation of restriction fragments corresponding to the T-DNA left and right border sequences in the backcross progeny. Isozyme and restriction fragment length polymorphism (RFLP) markers were used to test linkage relationships of the insertion in each backcross family. The T-DNA inserts in 9 of the 10 transformants were mapped in relation to one or more of these markers, and each mapped to a different chromosomal location. Because only one insertion did not show linkage with the markers employed, it must be located somewhere other than the genomic regions covered by the markers assayed. We conclude that Agrobacterium-mediated insertion in the Lycopersicon genome appears to be random at the chromosomal level. No discrepancies were found between the T-DNA genotype and the nopaline phenotype in the 322 backcross progeny of the nopaline positive transformants. Backcross progeny of two nopaline negative transformants showed incomplete correspondence between the T-DNA genotype and the kanamycin resistance phenotype. No alteration of T-DNA was observed in progeny showing a discrepancy between T-DNA and kanamycin resistance. However, two kanamycin resistant progeny plants of one of these two transformants possessed altered T-DNA restriction patterns, indicating genetic instability of the T-DNA in this transformant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330188
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  • 3
    Electronic Resource
    Electronic Resource
    Brain monoamines after portacaval anastomosis (1986)
    Springer
    Metabolic brain disease 1 (1986), S. 45-52 
    Details
    ISSN: 1573-7365
    Keywords: hepatic encephalopathy ; high-performance liquid chromatography ; liver disease ; monoamine neurotransmitters ; portacaval shunting ; rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Norepinephrine, dopamine, and serotonin, as well as the serotonin metabolite, 5-hydroxy-indoleacetic acid, were measured in whole-brain extracts from rats with a portacaval shunt or sham operation. Norepinephrine, serotonin, and 5-hydroxyindoleacetic acid were significantly higher after shunting. There was no difference in dopamine. The results support the idea that brain indole metabolism is increased during chronic hepatic encephalopathy. However, they provide evidence against suggestions that hepatic encephalopathy in general is accompanied by a shortage in the whole-brain content of the catecholamines norepinephrine and dopamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00998476
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  • 4
    Electronic Resource
    Electronic Resource
    Regional blood-brain barrier transport of glucose after portacaval anastomosis (1986)
    Springer
    Metabolic brain disease 1 (1986), S. 119-128 
    Details
    ISSN: 1573-7365
    Keywords: glucose transport ; blood-brain barrier ; regional glucose utilization ; portacaval anastomosis ; hepatic encephalopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The regional influx of glucose across the blood-brain barrier was measured in rats 5 to 6 weeks after a portacaval anastomosis or sham operation. D-[14C]Glucose was infused intravenously for 15sec while arterial blood was sampled continuously for measurement of plasma radioactivity and glucose concentration. Brain tissue radioactivity was measured by quantitative autoradiography. Glucose influx and plasma clearance (permeability times surface area;PS) were calculated from the net disintegrations per minute per gram in brain, the plasma radioactivity integral, and the plasma glucose concentration. In shunted rats influx was decreased by about 22% (in the brain as a whole) compared to that in controls. This decrease was almost entirely due to the decrease in plasma glucose concentrations (27%). ThePS, normalized to take plasma concentrations into account, showed a slight decrease in most of the brain except the telencephalon. For the brain as a whole this decrease amounted to 11%. The regionalPS and glucose utilization are known to be coupled and the relationship between these was the same in sham-operated and shunted rats. The decrease inPS observed in shunted rats was commensurate with their lower rates of glucose use; thus, the transport process of glucose from plasma to brain appeared to be unaffected by portacaval shunting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00999382
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  • 5
    Electronic Resource
    Electronic Resource
    Post-transcriptional regulation and DNA undermethylation of intracisternal A particle genes in embryonal carcinoma cell lines (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 125-133 
    Details
    ISSN: 0192-253X
    Keywords: retrovirus ; embryonal carcinoma ; embryonic gene ; DNA methylation ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Northern blot analysis and in vitro nuclear transcription assays were performed in order to clarify conflicting reports on the expression of intracisternal A particle (IAP) genes in embryonal carcinoma (EC) cell lines. Results demonstrate that post-transcriptional mechanisms control the final steady-state levels of IAP RNA in EC cells. IAP genes were further found to be undermethylated in IAP-expressing EC cell lines.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080302
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  • 6
    Electronic Resource
    Electronic Resource
    Control of early gene expression in Dictyostelium (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 337-350 
    Details
    ISSN: 0192-253X
    Keywords: Dictyostelium ; cAMP ; receptor ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have examined the expression of a cAMP pulse-repressed and two cAMP pulse-induced genes in response to cAMP and caffeine under a number of different physiological conditions, and in several classes of developmental mutants altered in cAMP-mediated signal transduction pathways. The data presented help characterize the mutants with regard to early gene expression. Analysis of the data indicates that full induction of the pulse-induced or repression of the pulse-repressed genes requires cycles of activation and adaptation of the cAMP receptor but does not require a rise in intracellular cAMP. Comparison of the results obtained between different mutant classes suggests that repression and activation of the two classes of genes can be uncoupled, implying that different intracellular mechanisms control these processes. In addition, we examined the effects of caffeine and show that it can induce pulse-induced mRNA accumulation in the absence of cAMP.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090415
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of cis and trans elements involved in cAMP-inducible gene expression in Dictyostelium discoideum (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 435-454 
    Details
    ISSN: 0192-253X
    Keywords: cis-acting sequences ; trans-acting factors ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Expression of the Dictyostelium discoideum pst-cath (CP2) gene is transcriptionally regulated during multicellular development, and the gene is inducible in competent single cells following administration of exogenous cAMP. The 5′ flanking region of pst-cath (CP2) that extends from -313 to the Cap site (+-1) has previously been shown to contain sufficient cis,-acting regulatory elements for proper developmental and cAMP-inducible expression of a foreign gene [Datta and Firtel, 1987, Mol Cell Biol 7:149-159]. The -283 to -201 region includes two exceptional “G-boxes” centered at -233 and -217 respectively, and this ∼ 80 bp region is essential for basal as well as regulated expression of the pst-cath (CP2) gene. Here we summarize results obtained from a detailed analysis of a series of linker-scanner mutants and mutants that carry small internal deletions within the essential 80-bp region. Insertion of a synthetic oligonucleotide that includes the downstream G-box is demonstrated to rescue a low level of cAMP-inducible expression following insertion into cassette mutants. The effect of introducing a change in the relative spacing between regulatory elements has also been investigated.We have analyzed nuclear extracts for the presence of DNA-binding proteins that interact specifically with the pst-cath (CP2) regulatory region and identified two such putative trans-acting factors: (1) the AT-factor that is observed within a few hours following the onset of starvation and that binds tightly to stretches of alternating adenine-thymine residues (poly(dA-dT)); and (2) the AG-factor that is present in nuclear extracts of aggregated cells. Competition studies have demonstrated significant differences in the affinity that characterizes the binding of the two factors to G-box-containing sequences. The binding specificities of these DNA-binding proteins have been analyzed using gel mobility-shift and DNaseI footprinting assays.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090422
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  • 8
    Electronic Resource
    Electronic Resource
    Regulation of late gene expression in a temperature-sensitive cohesion-defective mutant of Dictyostelium discoideum (1986)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 7 (1986), S. 99-108 
    Details
    ISSN: 0192-253X
    Keywords: cell-cell contact ; development ; prestalk ; prespore ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have analyzed the expression of a series of developmentally regulated genes in the Dictyostelium discoideum strain JC-5. This strain has been previously described as a temperature-sensitive, cohesion-defective derivative of FR17, itself a temporally deranged mutant of wild-type NC-4. At restrictive temperature (27°C), JC-5 initially acquires EDTA-resistant cell contacts but at the time of tip formation (12 hr) loses the ability to make specific cell-cell associations and regresses to an amorphous mound of cells. We have found that genes preferentially expressed in either prespore or prestalk cells are expressed prior to the appearance of the cohesion defect in JC-5; the specific cell contact system defective in this strain is necessary for neither the proper initiation nor maintenance of expression of either prespore of prestalk genes. We have also found, by use of an in vitro cell suspension system, that JC-5 is temperature-sensitive with respect to gene expression several hours before the defect in cell cohesion is observable. Our data suggest that the defect in JC-5 is due to a specific lesion not in the late cohesion system but rather in a more general component that is required earlier in the developmental process.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020070205
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