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1.
Mouse (erythroleukemia, TSA8, and FM3A) cells and human (HeLa and HL-60) cells were pulse-labeled with [3H]thymidine and covalently closed circular DNA in the extrachromosomal fraction was analyzed by fluorography following polyacrylamide gel electrophoresis. Two discrete bands for mouse and at least one, different, band for human cells emerged in the position to which small circular DNA (less than 1 kb) migrate, suggesting there to be species-specific, preferentially labeled, small circular DNA in mammalian cells. The incorporation of [3H]thymidine into the DNA was inhibited by cycloheximide but unaffected by aphidicolin. Restriction enzyme (AluI) digestion of the DNA fraction from MEL cells produced approximately 120-, 100-, and 50-bp labeled DNA fragments. The origin of the pulse-labeled DNAs is discussed. 相似文献
2.
The Sau3A DNA family consists of unique alphoid human repetitive DNA which is prone to be excised from the chromosomes and exhibits restriction fragment length polymorphism. We studied the chromosomal localization of the DNA by in situ hybridization using cultured normal human lymphocytes. Under standard hybridization conditions, the sequence hybridized with the centromeric regions of chromosomes 1, 2, 4, 11, 15, 17, 18, 19 and X, but under high stringency hybridization conditions, it hybridized with the centromeric regions of chromosomes 1, 17 and X, and particularly chromosome 11. Based on these results, we discuss the evolutionary relationship among the sequences of the Sau3A DNA family. 相似文献
3.
The in-gel competitive reassociation (IGCR) procedure was successfullyapplied to construct a comprehensive library enriched in DNAfragments containing C5mCGG sequences from mouse liver and braingenomic DNA. For IGCR, methylation-insensitive restriction enzyme(Msp I) digests were used as target DNA and methylation-sensitiverestriction enzyme (Hpa II) digests as competitor DNA. Southernblot analysis indicated that 60 to 70% of the clones in thelibrary were derived from the methylated sites and overall enrichmentwas 200- to 1000-fold. IGCR was further applied to constructa library for the sites differentially methylated between brainand liver DNA. In the library, approximately 20% of the HpaII sites exhibited different degrees of methylation betweenthese tissues. 相似文献
4.
We have evaluated codon usage bias in Drosophila histone genes and have
obtained the nucleotide sequence of a 5,161-bp D. hydei histone gene repeat
unit. This repeat contains genes for all five histone proteins (H1, H2a,
H2b, H3, and H4) and differs from the previously reported one by a second
EcoRI site. These D. hydei repeats have been aligned to each other and to
the 5.0-kb (i.e., long) and 4.8-kb (i.e., short) histone repeat types from
D. melanogaster. In each species, base composition at synonymous sites is
similar to the average genomic composition and approaches that in the small
intergenic spacers of the histone gene repeats. Accumulation of synonymous
changes at synonymous sites after the species diverged is quite high. Both
of these features are consistent with the relatively low codon usage bias
observed in these genes when compared with other Drosophila genes. Thus,
the generalization that abundantly expressed genes in Drosophila have high
codon bias and low rates of silent substitution does not hold for the
histone genes.
相似文献
5.
6.
Rai Dilip Toshiyuki Ishii Hideki Imada Yuko Wada-Kiyama Ryoiti Kiyama Eiichi Miyachi Makoto Kaneda 《Journal of molecular histology》2013,44(6):639-644
There is increasing evidence that ATP acts on purinergic receptors and mediates synaptic transmission in the retina. In a previous study, we raised the possibility that P2X-purinoceptors, presumably P2X2-purinoceptors in OFF-cholinergic amacrine cells, play a key role in the formation of OFF pathway-specific modulation. In this study, we examined whether the P2Y1-purinoceptors can function in cholinergic amacrine cells in the mouse retina since cholinergic amacrine cells in the rat retina express P2Y1-purinoceptors. P2Y1-purinoceptors were shown to be expressed in dendrites of both ON- and OFF-cholinergic amacrine cells in adults. At postnatal day 7, there was immunoreactivity for P2Y1-purinoceptors in the soma of cholinergic amacrine cells. At postnatal day 14, weak immunoreactivity for P2Y1-purinoceptors was detected in the dendrites but not in the soma of cholinergic amacrine cells. At postnatal day 21, strong immunoreactivity for P2Y1-purinoceptors was detected in dendrites of cholinergic amacrine cells. The expression pattern of P2Y1-purinoceptors was not affected by visual experience. We concluded that P2Y1-purinoceptors are not involved in the OFF-pathway-specific signal transmission in cholinergic amacrine cells of the mouse retina. 相似文献
7.
We determined DNA bend sites in the promoter region of the human estrogen receptor (ER) gene by the circular permutation assay. A total of five sites (ERB-4 to -1, and ERB+1) mapped in the 3 kb region showed an average distance of 688 bp. Most of the sites were accompanied by short poly(dA) x poly(dT) tracts including the potential bend core sequence A2N8A2N8A2 (A/A/A). Fine mapping of the ERB-2 site indicated that this A/A/A and the 20 bp immediate flanking sequence containing one half of the estrogen response element were the sites of DNA curvature. All of the experimentally mapped bend sites corresponded to the positions of DNA curvature as well as to nucleosomes predicted by computer analysis. In vitro nucleosome mapping at ERB-2 revealed that the bend center was located 10-30 bp from the experimental and predicted nucleosome dyad axes. 相似文献
8.
Honma M Namikawa K Mansur K Iwata T Mori N Iizuka H Kiyama H 《Journal of neurochemistry》2002,82(4):961-975
Axotomy-induced neuronal death occurs in neonatal motoneurons, but not in adult rat. Here we demonstrated that during the course of postnatal development, nerve injury induced down-regulation of the glial cell line-derived neurotrophic factor (GDNF) receptor GFRalpha1 in axotomized hypoglossal motoneurons of rat are gradually converted to the adult up-regulation pattern of response. The compensatory expression of GFRalpha1 specifically in the injured motoneurons of neonates by adenovirus succeeded in rescuing the injured neurons without an application of growth factors. To the contrary, the nuclear antisense RNA for GFRalpha1 expression accelerates the axotomy-induced neuronal death in pups. These findings suggest that the receptor expression response after nerve injury is critical for the determination of injured motoneuron fate. 相似文献
9.
Takano R Hisahara S Namikawa K Kiyama H Okano H Miura M 《The Journal of biological chemistry》2000,275(21):16360-16365
Tumor necrosis factor-alpha is thought to be one of the most important inflammatory cytokines associated with the demyelinating disease multiple sclerosis. We determined whether neurotrophins could protect oligodendrocytes from tumor necrosis factor-alpha-mediated cytotoxicity. Among the neurotrophins tested, nerve growth factor was most effective at preventing cell death. Nerve growth factor also prevented the tumor necrosis factor-induced loss of mitochondrial membrane potential. Overexpression of constitutively active Akt, a downstream target of phosphatidylinositol 3-kinase, but not of constitutively active MEK, protected oligodendrocytes from tumor necrosis factor-induced injury. Moreover, overexpression of dominant-negative Akt negated the protective effects of nerve growth factor on tumor necrosis factor-mediated oligodendrocyte cytotoxicity. These findings indicate that the Akt pathway is crucial in nerve growth factor-mediated oligodendrocyte protection. 相似文献
10.
P Rodley N S Nishikawa M Hirota Y Wada-Kiyama C T Noguchi M Oishi R Kiyama 《DNA research》1998,5(6):349-354
We report here the locations of curved DNA in the human erythropoietin receptor gene. A total of 13 DNA bend sites were mapped by circular permutation assays, appearing at an average interval of 651.2+/-214.6 (S.D.) in the 8-kb region. The bend centers in these 13 bend sites were confirmed by oligonucleotide-based assays where most of these centers had bend angles higher than that shown by (AAACCGGGCC) x (A)20 and lower than that shown by (AAACCGGGCC)2 x (A)10. DNA curvature mapping by TRIF software, which is based on the distribution of dinucleotides, primarily AA and TT, provided a highly accurate prediction for the locations of the bend sites. They showed approximately 20 degrees to 40 degrees of bend angles demonstrated by the oligonucleotide assays and by computer analysis. 相似文献