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排序方式: 共有246条查询结果,搜索用时 15 毫秒
1.
Enhancer and promoter elements directing activation and glucocorticoid repression of the alpha 1-fetoprotein gene in hepatocytes. 总被引:23,自引:13,他引:10
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M Guertin H LaRue D Bernier O Wrange M Chevrette M C Gingras L Bélanger 《Molecular and cellular biology》1988,8(4):1398-1407
Mutations were introduced in 7 kilobases of 5'-flanking rat alpha 1-fetoprotein (AFP) genomic DNA, linked to the chloramphenicol acetyltransferase gene. AFP promoter activity and its repression by a glucocorticoid hormone were assessed by stable and transient expression assays. Stable transfection assays were more sensitive and accurate than transient expression assays in a Morris 7777 rat hepatoma recipient (Hepa7.6), selected for its strong AFP repression by dexamethasone. The segment of DNA encompassing a hepatocyte-constitutive chromatin DNase I-hypersensitive site at -3.7 kilobases and a liver developmental stage-specific site at -2.5 kilobases contains interacting enhancer elements sufficient for high AFP promoter activity in Hepa7.6 or HepG2 cells. Deletions and point mutations define an upstream promoter domain of AFP gene activation, operating with at least three distinct promoter-activating elements, PEI at -65 base pairs, PEII at -120 base pairs, and DE at -160 base pairs. PEI and PEII share homologies with albumin promoter sequences, PEII is a near-consensus nuclear factor I recognition sequence, and DE overlaps a glucocorticoid receptor recognition sequence. An element conferring glucocorticoid repression of AFP gene activity is located in the upstream AFP promoter domain. Receptor-binding assays indicate that this element is the glucocorticoid receptor recognition sequence which overlaps with promoter-activating element DE. 相似文献
2.
3.
We have broadly defined the DNA regions regulating esterase6 activity in
several life stages and tissue types of D. melanogaster using P-
element-mediated transformation of constructs that contain the esterase6
coding region and deletions or substitutions in 5' or 3' flanking DNA.
Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and
the primary sequences regulating its activity lie between -171 and -25 bp
relative to the translation initiation site: deletion of these sequences
decrease activity approximately 20-fold. Hemolymph activity is also
modulated by four other DNA regions, three of which lie 5' and one of which
lies 3' of the coding region. Of these, two have positive and two have
negative effects, each of approximately twofold. Esterase6 activity is
present also in two male reproductive tract tissues; the ejaculatory bulb,
which is another ancestral activity site, and the ejaculatory duct, which
is a recently acquired site within the melanogaster species subgroup.
Activities in these tissues are at least in part independently regulated:
activity in the ejaculatory bulb is conferred by sequences between -273 and
-172 bp (threefold decrease when deleted), while activity in the
ejaculatory duct is conferred by more distal sequences between -844 and
-614 bp (fourfold decrease when deleted). The reproductive tract activity
is further modulated by two additional DNA regions, one in 5' DNA (-613 to
-284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to
+2731 bp; threefold decrease when deleted) that probably overlaps the
adjacent esteraseP gene. Collating these data with previous studies
suggests that expression of EST6 in the ancestral sites is mainly regulated
by conserved proximal sequences while more variable distal sequences
regulate expression in the acquired ejaculatory duct site.
相似文献
4.
Functional analysis of developmentally regulated chromatin-hypersensitive domains carrying the alpha 1-fetoprotein gene promoter and the albumin/alpha 1-fetoprotein intergenic enhancer. 总被引:2,自引:2,他引:0
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5.
Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
相似文献
6.
Hennessey James V.; Chromiak Joseph A.; Dellaventura Shirley; Guertin Jennifer; Maclean David B. 《Journal of applied physiology》1997,82(6):1739-1742
Hennessey, James V., Joseph A. Chromiak, ShirleyDellaVentura, Jennifer Guertin, and David B. MacLean. Increasein percutaneous muscle biopsy yield with a suction-enhancementtechnique. J. Appl. Physiol. 82(6):1739-1742, 1997.The percutaneous muscle biopsy technique is usedin clinical practice and biomedical research. We developed a newenhanced-suction technique [suction-enhancing nipples(SEN)] and compared it with techniques currently in practice byassessing biopsy yields on anesthetized pigs. We applied the enhanced-suction technique to human subjects participating in aclinical trial. In the pig, there was a mean 91% (1.9-fold) increasein the size of the samples obtained with the 4-mm needle when SEN wasused and a mean 507% (fivefold) increase in sample size when the SENwas applied to the 6-mm needles. Nine passes of the 6-mm needle withSEN obtained from five consecutive human subjects yielded a meanindividual sample size of 109.4 mg or 219.4 mg per needle pass whenusing the double-sample technique. Adequate tissue samples forhistomorphometric and other analyses were obtained in all samplesobtained. The percutaneous muscle biopsy performed with enhancedsuction using inexpensive, readily available nipples enhances tissueyield two- to fivefold. 相似文献
7.
Tryptose phosphate broth confers to chick embryo cells resistance to the inhibitory effect of chloramphenicol on growth 总被引:1,自引:0,他引:1
L Leblond-Larouche A Larouche D Guertin R Morais 《Biochemical and biophysical research communications》1977,74(3):977-983
Tryptose phosphate broth (10% V/V) prevents the inhibitory effect of chloramphenicol (80 ug/ml) on the growth of chick embryo fibroblasts. Cellular cytochrome oxidase activity is rapidly lost indicating that chloramphenicol inhibits the mitochondrial protein-synthesizing system in the presence of the broth. To compensate for the apparent decreased mitochondrial ATP production, pyruvate kinase and lactate dehydrogenase activities, 2-deoxyglucose uptake and lactic acid produced in treated cells are greater than those in the control cells during the first few generations. These fermentation values tend to revert to normal during later cell generations. 相似文献
8.
A new method for preparation of nucleic acid specimens for electron microscopy has been adapted to study the interaction of proteins with DNA. Both a detergent and a basic protein are added to the DNA-protein solution before spreading on a hypophase containing 0.2 m ammonium acetate. This method has been tested using T7 DNA and Escherichia coli RNA polymerase. Specifically bound enzyme molecules were clearly visible on the well extended DNA molecules; the binding sites were located at 0.59, 1.24, 1.57, and 1.86% of the total length of T7 DNA. Under carefully controlled conditions, 40–85% of the DNA molecules specifically bound at least one enzyme molecule. 相似文献
9.
Valentin Popa Louis Morneau Céline Piché André Deshaies Eric Bauce Claude Guertin 《ZooKeys》2013,(348):97-124
Twig beetles in the genus Pityophthorus Eichhoff, 1864 include more than 300 species worldwide, with maximum diversity in tropical and subtropical regions. To date, approximately 50 species of Pityophthorus have been recorded in Canada, and these species are associated mainly with coniferous trees. Since 1981, no comprehensive study on this difficult taxonomic group has been conducted in Quebec, Canada, most likely due to their limited significance as forest pests. Based on data gathered from five years of field sampling in conifer seed orchards and compiled from various entomological collections, the distribution of Pityophthorus species in Quebec is presented. Approximately 291 new localities were recorded for the Pityophthorus species. Five species-group taxa, namely Pityophthorus puberulus (LeConte, 1868), Pityophthorus pulchellus pulchellus Eichhoff, 1869, Pityophthorus pulicarius (Zimmermann, 1868), Pityophthorus nitidus Swaine, 1917,and Pityophthorus cariniceps LeConte&Horn, 1876 were the most widespread. In contrast, Pityophthorus consimilis LeConte, 1878, Pityophthorus intextus Swaine, 1917, Pityophthorus dentifrons Blackman, 1922, Pityophthorus ramiperda Swaine, 1917, and Pityophthorus concavus Blackman, 1928 display a notably limited distribution. In addition, the first distribution records of Pityophthorus intextus and Pityophthorus biovalis Blackman, 1922 are furnished, and the subspecies Pityophthorus murrayanae murrayanae Blackman, 1922is reported from Quebec for the second time. Moreover, distribution maps are provided for all Pityophthorus species recorded in the province of Quebec. 相似文献