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排序方式: 共有193条查询结果,搜索用时 15 毫秒
1.
Transgenic mice selectively lacking MHC class II (I-E) antigen expression on B cells: an in vivo approach to investigate Ia gene function 总被引:9,自引:0,他引:9
G Widera L C Burkly C A Pinkert E C B?ttger C Cowing R D Palmiter R L Brinster R A Flavell 《Cell》1987,51(2):175-187
The E alpha MHC class II gene with 1.4 kb of 5'-flanking and 0.5 kb of 3'-flanking sequences was introduced into (H-2b X s)F2 mice, which do not express their endogenous E alpha gene. The transgene was expressed in thymic tissue and in adherent spleen cells and was induced in peritoneal exudate cells by gamma-interferon. In contrast to the normal E alpha gene, there was no expression in B lymphocytes. Since transgenic animals made with constructs containing 3.2 kb and 2 kb of 5'-flanking sequences show normal expression pattern of the E alpha gene, it appears that deletion of 5'-flanking sequences between -1.4 kb and -2 kb inactivated or eliminated regulatory sequences required for expression of E alpha specifically in B cells. The presence of pBR327 DNA linked to the -1.4 kb E alpha transgene suppresses expression in peripheral adherent cells, yielding mice expressing E alpha only in the thymus. These mice appear to be tolerant to I-E, as measured in mixed leukocyte response experiments. 相似文献
2.
Molecular pathogenesis of hepatocellular carcinoma in hepatitis B virus transgenic mice 总被引:52,自引:0,他引:52
F V Chisari K Klopchin T Moriyama C Pasquinelli H A Dunsford S Sell C A Pinkert R L Brinster R D Palmiter 《Cell》1989,59(6):1145-1156
3.
Cloning of a gamma 2b gene encoding anti-Pseudomonas aeruginosa H chains and its introduction into the germ line of mice 总被引:5,自引:0,他引:5
H Tsang C Pinkert J Hagman M Lostrum R L Brinster U Storb 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(1):308-314
A complete, functional gamma 2b gene (pVCM) was cloned from a mouse hybridoma (VD93) with antibody activity to Pseudomonas aeruginosa. DNA sequencing of the VDJ region of pVCM determined that the VH gene was a member of the J558 family rearranged to JH2. Upon transfection into myeloma cells the gamma 2b gene gave rise to high levels of gamma 2b mRNA and gamma 2b protein. The gamma 2b protein had the same IEF pattern as the parent hybridoma protein VD93 and the antibodies formed from a combination of the pVCM gamma 2b chains and the myeloma lambda-chains bound weakly to P. aeruginosa. However, the hybrid antibodies did not discriminate between the serotypes 2 and 3, whereas the parent protein was specific for serotype 3. Transgenic mice were produced with the pVCM gamma 2b gene which expressed the gamma 2b mRNA (both membrane and secreted forms) only in lymphoid organs. However, contrary to expectations, the gamma 2b mRNA levels were higher in T cells than in B cells in three different transgenic lines. The serum of the transgenic mice had no activity to P. aeruginosa indicating the importance of L chains for the conformation of the Ag binding site. These gamma 2b transgenic mice provide a convenient tool for the study of feedback inhibition of Ig gene rearrangement. 相似文献
4.
Immortalized differentiated hepatocyte lines derived from transgenic mice harboring SV40 T-antigen genes 总被引:9,自引:0,他引:9
D Paul M H?hne C Pinkert A Piasecki E Ummelmann R L Brinster 《Experimental cell research》1988,175(2):354-362
Hepatocytes of transgenic mouse fetuses harboring SV40 virus transforming gene sequences in the SV delta e-MGH fusion gene construct 202 driven by the mouse metallothionein (MT-I) enhancer [R. D. Palmiter, H. Y. Chen, A. Messing, and R. L. Brinster (1985) Nature (London) 316, 457-460] were cultured at Day 19 of gestation and established as a differentiated line expressing albumin and alpha-fetoprotein (AFP) mRNAs. Hepatocyte line FMH-202 contains integrated SV40 sequences, expresses SV40 T-antigen genes, and exhibits unlimited growth potential because it has been cultured 18 months without apparent decrease in cell viability or in growth rate that could suggest the occurrence of a crisis period. Immortalized cells multiply in chemically defined medium deficient in arginine with transferrin plus insulin, whereas EGF, insulin, and transferrin are obligatory requirements for fetal or newborn mouse hepatocyte multiplication in primary cultures. Cells did not grow in agar and were not tumorigenic in nude mice. Their immortalized, nonmalignant phenotype was further documented by low saturation densities of confluent monolayers showing no overgrowth, and by growth arrest in the absence of insulin with subsequent induction of DNA synthesis and resumption of cell growth in response to insulin. Thus, it appears that immortalized SV40 T-antigen-expressing hepatocytes are present in the liver of the transgenic mice. However, at later points in liver development the transforming activity of T-antigen becomes apparent and leads to hepatocellular carcinoma formation in vivo. 相似文献
5.
Expression of hepatitis B virus large envelope polypeptide inhibits hepatitis B surface antigen secretion in transgenic mice. 总被引:27,自引:17,他引:10 下载免费PDF全文
F V Chisari P Filippi A McLachlan D R Milich M Riggs S Lee R D Palmiter C A Pinkert R L Brinster 《Journal of virology》1986,60(3):880-887
The outer membrane of the hepatitis B virus consists of host lipid and the hepatitis B virus major (p25, gp28), middle (gp33, gp36), and large (p39, gp42) envelope polypeptides. These polypeptides are encoded by a large open reading frame that contains three in-phase translation start codons and a shared termination signal. The influence of the large envelope polypeptide on the secretion of hepatitis B surface antigen (HBsAg) subviral particles in transgenic mice was examined. The major polypeptide is the dominant structural component of the HBsAg particles, which are readily secreted into the blood. A relative increase in production of the large envelope polypeptide compared with that of the major envelope polypeptide led to profound reduction of the HBsAg concentration in serum as a result of accumulation of both envelope polypeptides in a relatively insoluble compartment within the cell. We conclude that inhibition of HBsAg secretion is related to a hitherto unknown property of the pre-S-containing domain of the large envelope polypeptide. 相似文献
6.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
7.
8.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
9.
Transgenic Research - 相似文献
10.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献