首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The nature of the Ohv mutation of the X chromosome of the mouse is defined. This locus exerts a cis position effect upon the expression of genes Tfm and Blo mapping in the same region; genes on the same chromosome as the Ohv mutation are preferentially activated and genes on the other X chromosome are usually inactive. Following the proportion of Tfm cells in the kidneys of heterozygotes confirms that the variegation seen of the locus Blo in the coat is matched in inner tissues. By introducing the sex reversal gene Sxr into these stocks, a situation can be created in which wildtype kidney cells have a selective advantage over Tfm cells in the embryonic Wolfflan duct and urogenital sinus. In spite of this difference in cell advantages, Blo coat variegation and Tfm Wolffian duct cell preponderance continue to exhibit a good correlation. This excludes the possibility that the variegation depends upon a selective advantage of cells carrying Tfm alleles after random X-inactivation and therefore reinforces the conclusion that the Ohv mutation is directly concerned in the X-activation process. A model is presented in which this locus acts as a receptor site recognized by molecules which activate one X chromosome.  相似文献   

2.
S Ono  L N Geller  E V Lai 《Cell》1974,3(3):235-242
The sexual behavior of mice of various genotypes has been studied in our stock in which X-linked genes, Tfm and (Ohv), as well as an autosomal dominant gene, Sxr, are maintained. Since the absence of neonatal imprinting in Tfm (Ohv)/Y leads to no sexual behavior, we conclude that neonatal imprinting is the prerequisite for feminization as well as masculinization of the central nervous system. Since individual components of sexual behavior may become feminine or absent instead of being masculine in sex-reversed Tfm (Ohv)/+(O+, Sxr/+ with mosaic brains, we conclude that neonatal imprinting directly involves individual neurons, and that different degrees of imprinting by the same agent lead to masculinization or feminization. In accordance with recent views, we believe estradiol to be this imprinting agent.We envisage the role of the Tfm locus in the central nervous system as follows: within individual neurons for sexual behavior, the synthesis of aromatizing enzymes is normally inducible by androgens; these enzymes are therefore noninducible in Tfm (Ohv)/Y. In normal neonates, exposure to testosterone leads to the induced intracellular conversion of testosterone to estradiol, self imprinting by estradiol causing masculinization. Feminization may normally be due to the direct exposure of these neurons to a low circulating concentration of estradiol. An alternative explanation might be that the estradiol-receptor protein in these neurons also is normally inducible by testosterone. In this case, neonatally testosterone-exposed neurons would become inherently more responsive to estradiol than neonatally estradiol-exposed neurons.  相似文献   

3.
Ulrich Drews  Ute Drews 《Cell》1975,6(4):475-479
Mosaic mice composed of androgen-insensitive Tfm and androgen-sensitive wild-type cells are constructed by virtue of the natural X inactivation: XX mice heterozygous for X-linked testicular feminization (Tfm) are reverted to males by the sex reversal (Sxr) mutation. After stimulation with testosterone, in the epididymis of the mosaic mice, the incorporation of 3H-thymidine is compared in both cell fractions. The labeling index of Tfm and wild-type cells is in the same order of magnitude. The result indicates that the stimulus for DNA synthesis exerted by testosterone is conveyed from the androgen-sensitive wild-type to the androgen-insensitive Tfm cells by metabolic cooperation on tissue level.On the other hand, the proportion of Tfm cells in the epididymal mosaic is far less than expected from X inactivation. The reason is that in the mosaic, in spite of normal proliferation, the undifferentiated Tfm cells die off steadily. Typical dense bodies are observed as signs of physiological cell death.  相似文献   

4.
OUR previous studies on the X-linked testicular feminization (Tfm) mutation1 of the mouse2–4 showed that the so-called cytosol and nuclear 5αx-dihydrotestosterone (DHT) receptor protein5–7 might be a regulatory protein specified by the Tfm locus. The dual role of being a translational repressor in the cytoplasma and a mediator of hypertrophy in the nucleus was envisaged8. We found, however, another class of androgen-receptor in the polysome fraction of kidney proximal tubule cells which seems better qualified to be a translational regulator. Since a single gene locus specifies only one kind of polypeptide chain, we re-examined whether the cytosol and nuclear DHT-receptor protein underwent a true mutational change in Tfm/Y individuals.  相似文献   

5.
Summary Hemoglobin J Mexico, an chain mutant, was studied in eight unrelated Algerian families. The quantities of the abnormal hemoglobin in 116 subjects are trimodally distributed: 55% in homozygotes, 31% and 38% in heterozygotes. Both hematological data and the / chain biosynthetic ratio are normal in heterozygotes with 31% Hb J and in homozygotes. In contrast, the MCV and MCH as well as the / biosynthetic ratio are slightly reduced in heterozygotes with 38% Hb J and in their relatives carrying Hb A. The elevated expression of J chains in heterozygotes with 38% Hb J may be due to an thalassemia gene trans to the >J locus.  相似文献   

6.
B Attardi  S Ono 《Cell》1974,2(4):205-212
Steroid binding has been studied in cytoplasmic extracts of normal mouse kidney, an androgen sensitive organ, and of kidney from mice affected with testicular feminization (Tfm mutant) that have inherited androgen resistance. Macromolecules that bind 3H-5α-dihydrotestosterone (DHT, the presumed active androgen in most testosterone target organs) and sediment in glycerol gradient at 8–9S can be observed in cytosol from kidney of mice of different sex, age, and hormonal history. The 8–9S component from normal females is heat labile, pronase sensitive, and dissociated by high salt to a lower molecular weight entity. The apparent equilibrium dissociation constant (Kd) for the DHT-receptor complex is 1.4 × 10?9M, and there are about 1500 binding sites per testosterone-sensitive kidney proximal tubule cell. Cytosol from Tfm/Y animals also shows a sharp peak of 3H-DHT-binding activity at 8–9S. The Tfm protein, however, has reduced affinity for DHT and binds only 10–25% as much 3H-DHT as wild-type receptor at 3H-DHT concentrations from 5 × 10?11M to 1.2 × 10?8M. Scatchard analysis, and studies involving competition with unlabeled steroids, relative binding of various androgens, and dissociation of the 3H-DHT-binding protein complex after extensive dialysis have led to the conclusion that Tfm kidney contains very little, if any, androgen receptor with properties similar to that found in normal kidney.  相似文献   

7.
Genome-wide association studies (GWASs) of follicular lymphoma (FL) have previously identified human leukocyte antigen (HLA) gene variants. To identify additional FL susceptibility loci, we conducted a large-scale two-stage GWAS in 4,523 case subjects and 13,344 control subjects of European ancestry. Five non-HLA loci were associated with FL risk: 11q23.3 (rs4938573, p = 5.79 × 10−20) near CXCR5; 11q24.3 (rs4937362, p = 6.76 × 10−11) near ETS1; 3q28 (rs6444305, p = 1.10 × 10−10) in LPP; 18q21.33 (rs17749561, p = 8.28 × 10−10) near BCL2; and 8q24.21 (rs13254990, p = 1.06 × 10−8) near PVT1. In an analysis of the HLA region, we identified four linked HLA-DRβ1 multiallelic amino acids at positions 11, 13, 28, and 30 that were associated with FL risk (pomnibus = 4.20 × 10−67 to 2.67 × 10−70). Additional independent signals included rs17203612 in HLA class II (odds ratio [ORper-allele] = 1.44; p = 4.59 × 10−16) and rs3130437 in HLA class I (ORper-allele = 1.23; p = 8.23 × 10−9). Our findings further expand the number of loci associated with FL and provide evidence that multiple common variants outside the HLA region make a significant contribution to FL risk.  相似文献   

8.
Psoriasis (PS) and Crohn disease (CD) have been shown to be epidemiologically, pathologically, and therapeutically connected, but little is known about their shared genetic causes. We performed meta-analyses of five published genome-wide association studies on PS (2,529 cases and 4,955 controls) and CD (2,142 cases and 5,505 controls), followed up 20 loci that showed strongest evidence for shared disease association and, furthermore, tested cross-disease associations for previously reported PS and CD risk alleles in additional 6,115 PS cases, 4,073 CD cases, and 10,100 controls. We identified seven susceptibility loci outside the human leukocyte antigen region (9p24 near JAK2, 10q22 at ZMIZ1, 11q13 near PRDX5, 16p13 near SOCS1, 17q21 at STAT3, 19p13 near FUT2, and 22q11 at YDJC) shared between PS and CD with genome-wide significance (p < 5 × 10−8) and confirmed four already established PS and CD risk loci (IL23R, IL12B, REL, and TYK2). Three of the shared loci are also genome-wide significantly associated with PS alone (10q22 at ZMIZ1, prs1250544 = 3.53 × 10−8, 11q13 near PRDX5, prs694739 = 3.71 × 10−09, 22q11 at YDJC, prs181359 = 8.02 × 10−10). In addition, we identified one susceptibility locus for CD (16p13 near SOCS1, prs4780355 = 4.99 × 10−8). Refinement of association signals identified shared genome-wide significant associations for exonic SNPs at 10q22 (ZMIZ1) and in silico expression quantitative trait locus analyses revealed that the associations at ZMIZ1 and near SOCS1 have a potential functional effect on gene expression. Our results show the usefulness of joint analyses of clinically distinct immune-mediated diseases and enlarge the map of shared genetic risk loci.  相似文献   

9.
Divalent cobalt ions (Co2+) induce the expression of hypoxia responsive genes and are often used in cell biology to mimic hypoxia. In this in vitro study we compared the effects of hypoxia and Co2+ on human endothelial cells and examined processes that are stimulated in hypoxia in vivo (proliferation and angiogenesis). We analyzed the expression of the hypoxia-inducible factor-1 (HIF-1) under different hypoxic conditions (3% and nearly 0% O2) and Co2+-concentrations (0.01–0.7 mM). As in hypoxia, the amount of HIF-1 protein was enhanced by exposure to Co2+ (did not correlate with mRNA amount). However, contrary to the results of hypoxia, in vitro-angiogenesis was inhibited after exposure to even low Co2+-concentrations (0.01 mM). This led to the conclusion that although hypoxia signaling after Co2+-exposure took place, further yet unknown Co2+-induced event(s) must have occurred. (Mol Cell Biochem 270: 157–166, 2005)  相似文献   

10.
TP53 protects cells from transformation by responding to stresses including aneuploidy and DNA double-strand breaks (DSBs). TP53 induces apoptosis of lymphocytes with persistent DSBs at antigen receptor loci and other genomic loci to prevent these lesions from generating oncogenic translocations. Despite this critical function of TP53, germline Tp53−/− mice succumb to immature T-cell (thymic) lymphomas that exhibit aneuploidy and lack clonal translocations. However, Tp53−/− mice occasionally develop B lineage lymphomas and Tp53 deletion in pro-B cells causes lymphomas with oncogenic immunoglobulin (Ig) locus translocations. In addition, human lymphoid cancers with somatic TP53 inactivation often harbor oncogenic IG or T-cell receptor (TCR) locus translocations. To determine whether somatic Tp53 inactivation unmasks translocations or alters the frequency of B lineage tumors in mice, we generated and analyzed mice with conditional Tp53 deletion initiating in hematopoietic stem cells (HSCs) or in lineage-committed thymocytes. Median tumor-free survival of each strain was similar to the lifespan of Tp53−/− mice. Mice with HSC deletion of Tp53 predominantly succumbed to thymic lymphomas with clonal translocations not involving Tcr loci; however, these mice occasionally developed mature B-cell lymphomas that harbored clonal Ig translocations. Deletion of Tp53 in thymocytes caused thymic lymphomas with aneuploidy and/or clonal translocations, including oncogenic Tcr locus translocations. Our data demonstrate that the developmental stage of Tp53 inactivation affects karyotypes of lymphoid malignancies in mice where somatic deletion of Tp53 initiating in thymocytes is sufficient to cause thymic lymphomas with oncogenic translocations.  相似文献   

11.
Three new multidentate ligands designed to have high affinity for Ga3+, In3+ and Fe3+ have been synthesized, N-(2-hydroxybenzyl)-N′-pyridoxylethylenediamine-N,N′-diacetic acid (HBPLED), N-(2-hydroxy-3,5-dimethylbenzyl)-N′-(3-hydroxy-1,2,5-trimethyl-4-pyridylmethyl)ethylenediamine-N,N′-diacetic acid (Me4HBPLED) and N,N′-bis(3-hydroxy-1,2,5-trimethyl-4-pyridylmethyl) ethylenediamine-N,N′-diacetic acid (DMPLED). These ligands give metal-ligand (M–L) complexes with (M = Ga3+, In3+, Fe3+) overall charges of −1, 0 and + 1, respectively. The 67Ga, 68Ga and 111In complexes of each of the three ligands and the 59Fe complex of Me4HBPLED were prepared, characterized and their biodistributions determined in rats after intravenous injection. Despite the differences in overall charge, the biological behavior of all three 111In complexes were similar, in that the radioactivity cleared rapidly via the kidney. The biodistributions of the 68Ga and 67Ga complexes were comparable to that of the 111In complex counterpart. Also, the 59Fe-Me4HBPLED biodistribution was not significantly different from those of the 68Gaand 111In-Me4HBPLED. The renal clearance rate seems insensitive to the overall M-L charge; suggesting that the hydrophilic periphery of the ligand rather than the overall molecular charge determines the biological fate (with respect to renal clearance).  相似文献   

12.
The mechanism of hydrolysis of 4-methylumbelliferyl 3-deoxy-d-glycero--d-galacto-2-nonulopyranosidonic acid (KDN2MeUmb,4) by KDN-sialidase isolated from the hepatopancreas of the oysterCrassostrea virginica has been monitored by1H NMR spectroscopy. The results of these experiments reveal that KDN-sialidase catalyses the hydrolysis of the synthetic substrate KDN2MeUmb, with initial release of -d-KDN. This is consistent with an overall mechanism for the hydrolysis which proceeds with retention of anomeric configuration. These results agree with earlier NMR studies of otherN-acetylneuraminic acid-recognising sialidases from both viral and bacterial sources.  相似文献   

13.
Isolated somatic embryos from petiole-derived callus cultures ofVitis rupestris Scheele have been employed in experiments on genetic transformation. Co-cultivation of somatic embryos during embryogenesis induction withAgrobacterium tumefaciens strain LBA4404, which contains the plasmid pBI121 carrying the neomycin phosphotranspherase and the-glucuronidase genes, produced transformed cellular lines capable of recurrent somatic embryogenesis. Precocious selection for high levels of kanamycin (100 mgl-1) was an important part of our transformation protocol. Transformed lines still have strong-glucuronidase expression as well as stable insertion of the marker genes after 3 years of in-vitro culture, during which they have maintained their capacity to organize secondary embryos and to regenerate transgenic plants with an agreeable efficiency (13%).  相似文献   

14.
A newly discovered hybrid zone between two karyotypic races, ??gucki M?yn (g/r, h/k, i/o, j/l, m/n, p, q) and Popielno (g/r, h/q, i/k, j/l, m/n, o, p), of the common shrewSorex araneus Linnaeus, 1758 has been studied in north-eastern Poland. In the ??gucki M?yn/Popielno hybrid zone the complex heterozygotes form theoretically only short meiotic chain configurations, consisting of four or five elements. In all hybrid populations a high frequency of complex heterozygotes was observed, varying from 0.30 to 0.43 between localities. In the centre of the hybrid zone the frequencies of telocentricsh andk increased. In two individuals of the hybrid populations (Krutyń I and Krutyń II), homozygous telocentric for chromosome armsh, i, k, o andq were observed.  相似文献   

15.
Ribulose bisphosphate carboxylase (EC 4.1.1.39) from Thiobacillus A2 has been purified to homogeneity on the basis of polyacrylamide gel electrophoresis and U.V. analysis during sedimentation velocity studies. The enzyme had an optimum pH of about 8.2 with Tris-HCl buffers. The molecular weight was about 521000 with an S rel. of 16.9. K m for RuBP was 122 M, for total CO2 it was 4.17 mM, and for Mg2+ 20.0 M. The absolute requirement for a divalent cation was satisfied by Mg2+ which was replaceable to a certain extent by Mn2+. Activity was not significantly affected by SO 4 2- , SO 3 2- , or S2O 3 2- at 1.0 mM. At this concentration S2- caused a 27% stimulation. All mercurials tested were inhibitory. pHMB was the most potent causing about 60% inhibition at 0.01 mM. This inhibition was reversible by low concentrations of cysteine. Cyanide was also inhibitory. Its mode of inhibition with respect to RuBP was un-competitive and with a K i of 20 M. Lost activity could be restored partially by GSH or Cu2+. Although azide at the concentration tested had no significant effect on enzyme activity, 2,4-dinitrophenol at 1.0 mM caused 91% inhibition. Finally, activity was also affected by energy charge.Abbreviations ATP adenosine-5-triphosphate - GAPDH glyceraldehyde phosphate dehydrogenase - GSH (reduced) glutathione - G6P glucose-6-phosphate - NAD+ nicotinamide adenine dinucleotide - NADP+ nicotinamide adenine dinucleotide phosphate - pHMB parahydroxymercuribenzoate - 6PG 6-phosphogluconate - 3-PGA 3-phosphoglycerate - PGK phosphoglyceratekinase - RuBP ribulose-1,5-bisphosphate  相似文献   

16.
Partially purified plasma membrane fractions were prepared from guinea-pig pancreatic acini. These membrane preparations were found to contain an ATP-dependent Ca2+-transporter as well as a heterogenous ATP-hydrolytic activity. The Ca2+-transporter showed high affinity for Ca2+ (KCa 2+ = 0.04 ± 0.01 M), an apparent requirement for Mg2+ and high substrate specificity. The major component of ATPase activity could be stimulated by either Ca2+ or Mg2+ but showed a low affinity for these cations. At low concentrations, Mg2+ appeared to inhibit the Ca2+-dependent ATPase activity expressed by these membranes. However, in the presence of high Mg2+ concentration (0.5–1 mM), a high affinity Ca2+-dependent ATPase activity was observed (KCa 2+ = 0.08 ± 0.02 M). The hydrolytic activity showed little specificity towards ATP. Neither the Ca2+-transport nor high affinity Ca2+-ATPase activity were stimulated by calmodulin. The results demonstrate, in addition to a low affinity Ca2+ (or Mg+)-ATPase activity, the presence of both a high affinity Ca2+-pump and high affinity Ca2+-dependent ATPase. However, the high affinity Ca2+-ATPase activity does not appear to be the biochemical expression of the Ca2+-pump.Abbreviations Ca2+-ATPase calcium-activated, magnesium-dependent adenosine triphosphatase - CaM calmodulin - CDTA trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetate - EDTA ethylene-diaminetetraacetate - EGTA ethylene glycol bis(-aminoethyl ether)-N,N,N,N-tetraacetate - NADPH reduced form of nicotinamide adenine dinucleotide phosphate  相似文献   

17.
Summary The influence of unbalanced mating systems — factorial mating (FM) and random loss of families after a full diallel crossing (RS) — on the ultimate probability of gene fixation (u()) and the time required to fix or lose a gene (t()) are investigated. The average u() of these systems is smaller than that of random mating, and the range of u() for a given initial parental genotype combination is very large (close to one for most initial genotypic combinations). The average u() of different parental genotypic combinations of a given gene frequency are different. These systems accelerate the t().This article was written and prepared by U.S. Government employees on official time, and it is therefore in the public domain  相似文献   

18.
《Gene》1997,184(2):163-167
Mouse Ocp2-rs2 maps to chromosome 11 and encodes an 18.6 kDa peptide abundantly expressed in the organ of Corti. We show that sequences similar to murine Ocp2-rs2 are found on human chromosomes 4p16.2-4p14, 5p13-5q35.2, 7pter-q22, 10 and 12p13-12qter as revealed by Southern blot analyses of human/rodent somatic cell hybrids. A fetal human inner ear cDNA library was screened with a cloned 254 bp PCR product of murine Ocp2-rs2. One of two human cDNA clones (CM1) was sequenced from the 5′ end that begins with murine Ocp2-rs2 codon 14 through the stop codon and 258 nucleotides of 3′-UTR and was found to have the identical deduced amino acid sequence to Ocp2-rs2. Based on the sequence in the 3′-UTR of CM1, a PCR primer pair was synthesized and used to confirm that a human homologue of Ocp2-rs2, designated OCP2 and expressed in the developing human inner ear, is localized to 5q22-5q35.2. Other OCP2-like sequences located on chromosomes 4p16.2-4p14, 7pter-q22 and 12p13-12qter (but not the chromosome 10 OCP2-like sequence) will PCR amplify the expected size product at a lower annealing temperature using the OCP2 3′-UTR PCR primers indicating that there may be a human OCP2 gene family.  相似文献   

19.
20.
Summary Twenty-two independent man-mouse (A9, HGPRT-) and manhamster (CH, HGPRT)-hybrids using male human with balanced reciprocal translocation XY t(X;12)(q2,3;q1,2) were analysed for human genes localized on chromosome 12 (LDHB, PepB, ENO2, TPI), on chromosome X (PGK, GALA, G6PD) and for human chromosomes in relation with the balanced reciprocal translocation (chromosome 12, 12q-, Xq+). The human chromosome 12q- was not analysed because of its morphology is similar to some rodent chromosomes.The following results were obtained:1.Man-mouse hybrids (12 independent hybrids):The chromosome 12 is absent. A positive correlation is observed between Xq+, PGK, and PepB. Four hybrids are Xq++PGK+PepB+ and eight hybrids are Xq+-PGK-PepB-This result indicate that the genes for human PGK, PepB are on the chromosome Xq+. 2.Man-hamster hybrids (10 independent hybrids):A positive correlation is observed between Xq+, PGK, GALA. Two hybrids are Xq++PGK+GALA+ and eight hybrids are Xq+-PGK-GALA-.A positive correlation is observed between Xq+, PGK, GALA, PepB with the seven hybrids missing the normal human chromosome 12. One hybrid is Xq++PGK+GALA+PepB+ and six hybrids are Xq+-PGK-GALA-PepB-. These results indicate that the genes for human PGK, GALA, PepB are on the chromosome Xq+. 3.Man-mouse and man-hamster hybrids:The highest percentage of presence in the hybrids is observed for the following markers: G6PD (100%), LDHB, TPI, ENO2 (90%). This is explained by the fact that these hybrids selected in HAT medium, had to retain a segment of X (Xq+ or 12q-) bearing the human HGPRT gene. The different results indicated that the segment of X retained in these hybrids must be on the 12q- and not on the Xq+, for Xq+ is rarely present in man rodent hybrids.The different results implicate finally the following localisations:LDHB, TPI, ENO2 on 12 q12 12pter,PepB on 12 q12 12qter;PGK, GALA on X q23 Xpter;HGPRT, G6PD on X q23 Xqter.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号