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271.
The white gene as a marker in a new P-element vector for gene transfer in Drosophila. 总被引:60,自引:1,他引:59
We describe new vectors suitable for P-element mediated germ line transformation of Drosophila melanogaster using passenger genes whose expression does not result in a readily detectable phenotypic change of the transformed flies. The P-element vectors contain the white gene fused to the heat shock protein 70 (hsp70) gene promoter. Expression of the white gene rescues the white phenotype of recipient flies partly or completely even without heat treatment. Transformed descendents of most founder animals (GO) fall into two classes which are distinguishable by their orange and red eye colours. The different levels of white expression are presumably due to position effects associated with different chromosomal sites of insertion. Doubling of the gene dose in orange eyed fly stocks results in an easily visible darkening of the eye colour. Consequently, the generation of homozygous transformants is easily possible by simple inbreeding due to the phenotypic distinction of homo- and heterozygous transformants. Cloning into these P-element vectors is facilitated by the presence of polylinkers with 8 and 12 unique restriction sites. 相似文献
272.
Mammalian DNA polymerase alpha: a replication competent holoenzyme form from calf thymus. 总被引:7,自引:5,他引:2
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A complex "replication competent" holoenzyme form of DNA polymerase alpha (RC-alpha) was purified 10,000 fold from calf thymus through the use of an assay employing primed single stranded circular DNA template. The RC-alpha form could partially replicate a double-stranded oligo(dT)-tailed linear DNA and could completely convert primed single-stranded circular DNA to its double stranded form. The RC-alpha was resolved by denaturing gel electrophoresis into at least 10 discrete polypeptide species ranging in apparent molecular mass from 200 to 47 kilodaltons; three of the bands (apparent Mr of 200, 118 and 63 kilodaltons) displayed DNA polymerase activity in denaturing gel activity assay. The isolation of RC-alpha required the use of absolutely fresh calf thymus, the inclusion of ATP and protease inhibitors throughout the purification procedure. Treatment of the RC-alpha with the neutralizing anti-DNA polymerase alpha monoclonal antibody SJK 132-20 (Tanaka et al. (1982), J. Biol. Chem. 257, 8386-8390) in nondenaturing conditions selected the complete set of 10 polypeptides, whereas treatment in denaturing conditions selected the 200 kilodalton catalytic DNA polymerase active polypeptide. The properties and the behaviour of the RC-alpha preparation following removal of specific polypeptides strongly suggested that the capacity of RC-alpha to extend and replicate long template requires the function of nonproteolysed form of the 200 kilodaltons catalytic DNA polymerase core and at least 6 other auxiliary polypeptides of, respectively, 98, 87, 63, 54, 49 and 47 kilodaltons. 相似文献
273.
Crystal structure analysis of an A-DNA fragment at 1.8 A resolution: d(GCCCGGGC). 总被引:12,自引:9,他引:3
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Single crystals of the self-complementary octadeoxyribonucleotide d(GCCCGGGC) have been analysed by X-ray diffraction methods at a resolution of 1.8 A. The tetragonal unit cell of space group P4(3)2(1)2 has dimensions of a = 43.25 A and c = 24.61 A and contains eight strands of the oligonucleotide. The structure was refined by standard crystallographic techniques to an R factor of 17.1% using 1359 3 sigma structure factor observations. Two strands of the oligonucleotide are related by the crystallographic dyad axis to form a DNA helix in the A conformation. The d(GCCCGGGC) helix is characterized by a wide open major groove, a near perpendicular orientation of base pairs to the helix axis and an unusually small average helix twist angle of 31.3 degrees indicating a slightly underwound helix with 11.5 base pairs per turn. Extensive cross-strand stacking between guanine bases at the central cytosine-guanine step is made possible by a number of local conformational adjustments including a fully extended sugar-phosphate backbone of the central guanosine nucleotide. 相似文献
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277.
J. Ulrich Ph. U. Heitz T. Fischer E. Obrist F. Gullotta 《Virchows Archiv. B, Cell pathology including molecular pathology》1987,53(1):52-57
Eighteen granular cell tumors from various sites were examined with antisera directed against protein S-100, neuron specific enolase (NSE), alpha-1-antichymotrypsin, and alpha-1-antitrypsin, glial fibrillary acidic protein (GFAP), lysozyme, factor VIII-related antigen, myoglobin and vimentin, as well as with a monoclonal antibody (lu-5) directed against a panepithelial marker. The immunocytochemical reaction pattern of the tumors was heterogeneous. The brain and pituitary tumors and one thyroid tumor reacted for alpha-1-antichymotrypsin and alpha-1-antitrypsin, but not for S-100 protein and NSE. However, tumors from other sites showed immunoreactions for S-100 protein and NSE and some also for vimentin. Reactions for alpha-1-antichymotrypsin and alpha-1-antitrypsin were not observed. All other reactions were similarly negative. We conclude that the morphologically homogeneous group of granular cell tumors is biologically heterogeneous. 相似文献
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279.
The two new potent anthracycline antitumor antibiotics, morpholinodaunomycin and cyanomorpholinoadriamycin, are nonmutagenic or weakly mutagenic in Salmonella typhimurium or V79 Chinese hamster cells, but highly active inducing DNA repair in in cultured rat hepatocytes. Both agents were found to induce malignant transformation in vitro of C3H M2 mouse fibroblasts and mammary tumors in female Sprague-Dawley rats. The data indicate a) that these new anthracyclines, too, are highly oncogenic and b) in conjunction with previously published results, that the predictive value of in vitro short-term tests for in vivo carcinogenicity is dependent on the employment of a battery of such tests.Abbreviations ADM
adriamycin
- CNMoADM
cyanomorpholinoadriamycin
- DNM
daunomycin
- MNNG
N-methyl-N-nitro-N-nitrosoguanidine
Dedicated to Dr. J.H. Weisburger on his 65th birthday 相似文献
280.
Heat shock mRNA in mouse epidermis after UV irradiation 总被引:2,自引:0,他引:2
Total RNA from murine epidermis was extracted at different times after irradiation with erythemogenic doses of ultraviolet light (UVB or UVB/UVA) and hybridized to a DNA probe from the gene of a heat shock protein (hsp 70). An intense and transitory enrichment in RNA molecules hybridizing to the DNA probe was found between 15 and 120 min after irradiation, followed by a return to control levels over the next 70 h. Dose-response analysis indicates that 30 min after the irradiation, the relative amount of RNA hybridizing to the hsp 70 DNA probe increases with the dose (within the range explored: 0-180 mJ/cm2) up to values greater than 5 times the control. 相似文献