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971.
The gene for dominant white color in the pig is closely linked to ALB and PDGRFRA on chromosome 8. 总被引:1,自引:0,他引:1
M Johansson H Ellegren L Marklund U Gustavsson E Ringmar-Cederberg K Andersson I Edfors-Lilja L Andersson 《Genomics》1992,14(4):965-969
White is a widespread coat color among domestic pig breeds and is controlled by an autosomal dominant gene I. The segregation of this gene was analyzed in a reference pedigree for gene mapping developed by crossing the European wild pig and a Large White domestic breed. The gene for dominant white color was shown to be closely linked to the genes for albumin (ALB) and platelet-derived growth factor receptor alpha (PDGFRA) on chromosome 8. An unexpected phenotype with patches of colored and white coat was observed among the F1 and F2 animals. The segregation data indicated that the phenotype was controlled by a third allele, denoted patch (Ip), most likely transmitted by one of the Large White founder animals. It is shown that the ALB, PDGFRA, I linkage group shares homologies with parts of mouse chromosome 5, human chromosome 4, and horse linkage group II, all of which contain dominant genes for white or white spotting. Candidate genes for the dominant white and patch mutations in the pig are proposed on the basis on these linkage homologies and the recent molecular definition of the dominant white spotting (W) and patch (Ph) mutations in the mouse. 相似文献
972.
973.
974.
975.
Using an electric field pulse technique, we induced fusion between vacuoles and protoplasts of Kalanchoë daigremontiana , between protoplasts from etiolated and green leaf mesophyll, and between mesophyll protoplasts from plants of different physiological properties ( Avena sativa : C3 mechanism of photosynthesis, Kalanchoë daigremontiana : crassulacean acid metabolism). Close membrane contact amongst protoplasts or between protoplasts and vacuoles (as required for fusion) was achieved by the application of an alternating, non-uniform electric field to the suspension. Due to the dielectrophoresis effect the cells attach to each other along the field lines. The fusion process is initiated by the injection of an electric field pulse of high intensity and short duration (μs range). The field intensity has to be sufficiently high to induce reversible breakdown in the area of close membrane contact. After the application of the field pulse, the fusion process is initiated and completed within seconds to a few minutes, depending on the material investigated.
Fusion occurs between protoplasts and vacuoles as well as between protoplasts of different species. Both tonoplast and plasma membranes completely intermingled, indicating that in contrast to suggestions in the literature these membranes are compatible. Furthermore the cytoplasms of etiolated and green protoplasts obviously do not mix after fusion is completed, as etioplasts and chloroplasts kept separated from each other. In all experiments the volume of the fusion product equalled the sum of the compartments that underwent fusion. The wide spectrum of possible applications resulting from these fusion experiments in relation to metabolic problems is discussed. 相似文献
Fusion occurs between protoplasts and vacuoles as well as between protoplasts of different species. Both tonoplast and plasma membranes completely intermingled, indicating that in contrast to suggestions in the literature these membranes are compatible. Furthermore the cytoplasms of etiolated and green protoplasts obviously do not mix after fusion is completed, as etioplasts and chloroplasts kept separated from each other. In all experiments the volume of the fusion product equalled the sum of the compartments that underwent fusion. The wide spectrum of possible applications resulting from these fusion experiments in relation to metabolic problems is discussed. 相似文献
976.
H Eklund M Ingelman B O S?derberg T Uhlin P Nordlund M Nikkola U Sonnerstam T Joelson K Petratos 《Journal of molecular biology》1992,228(2):596-618
The structure of wild-type bacteriophage T4 glutaredoxin (earlier called thioredoxin) in its oxidized form has been refined in a monoclinic crystal form at 2.0 A resolution to a crystallographic R-factor of 0.209. A mutant T4 glutaredoxin gives orthorhombic crystals of better quality. The structure of this mutant has been solved by molecular replacement methods and refined at 1.45 A to an R-value of 0.175. In this mutant glutaredoxin, the active site residues Val15 and Tyr16 have been substituted by Gly and Pro, respectively, to mimic that of Escherichia coli thioredoxin. The main-chain conformation of the wild-type protein is similar in the two independently determined molecules in the asymmetric unit of the monoclinic crystals. On the other hand, side-chain conformations differ considerably between the two molecules due to heterologous packing interactions in the crystals. The structure of the mutant protein is very similar to the wild-type protein, except at mutated positions and at parts involved in crystal contacts. The active site disulfide bridge between Cys14 and Cys17 is located at the first turn of helix alpha 1. The torsion angles of these residues are similar to those of Escherichia coli thioredoxin. The torsion angle around the S-S bond is smaller than that normally observed for disulfides: 58 degrees, 67 degrees and 67 degrees for wild-type glutaredoxin molecule A and B and mutant glutaredoxin, respectively. Each sulfur atom of the disulfide cysteines in T4 glutaredoxin forms a hydrogen bond to one main-chain nitrogen atom. The active site is shielded from solvent on one side by the beta-carbon atoms of the cysteine residues plus side-chains of residues 7, 9, 21 and 33. From the opposite side, there is a cleft where the sulfur atom of Cys14 is accessible and can be attacked by a nucleophilic thiolate ion in the initial step of the reduction reaction. 相似文献
977.
978.
Narins SC Park EH Ramakrishnan R Garcia FU Diven JN Balin BJ Hammond CJ Sodam BR Smith PR Abedin MZ 《The Journal of membrane biology》2004,197(2):123-134
Gallbladder Na+ absorption is linked to gallstone formation in prairie dogs. We previously reported Na+/H+ exchanger (NHE1-3) expression in native gallbladder tissues. Here we report the functional characterization of NHE1, NHE2 and NHE3 in primary cultures of prairie dog gallbladder epithelial cells (GBECs). Immunohistochemical studies showed that GBECs grown to confluency are homogeneous epithelial cells of gastrointestinal origin. Electron microscopic analysis of GBECs demonstrated that the cells form polarized monolayers characterized by tight junctions and apical microvilli. GBECs grown on Snapwells exhibited polarity and developed transepithelial short-circuit current, Isc, (11.6 ± 0.5 µA · cm–2), potential differences, Vt (2.1 ± 0.2 mV), and resistance, Rt (169 ± 12 · cm2). NHE activity in GBECs assessed by measuring dimethylamiloride-inhibitable 22Na+ uptake under a H+ gradient was the same whether grown on permeable Snapwells or plastic wells. The basal rate of 22Na+ uptake was 21.4 ± 1.3 nmol · mg prot–1 · min–1, of which 9.5 ± 0.7 (~45%) was mediated through apically-restricted NHE. Selective inhibition with HOE-694 revealed that NHE1, NHE2 and NHE3 accounted for ~6%, ~66% and ~28% of GBECs total NHE activity, respectively. GBECs exhibited saturable NHE kinetics (Vmax 9.2 ± 0.3 nmol · mg prot–1 · min–1; Km 11.4 ± 1.4 mM Na+). Expression of NHE1, NHE2 and NHE3 mRNAs was confirmed by RT-PCR analysis. These results demonstrate that the primary cultures of GBECs exhibit Na+ transport characteristics similar to native gallbladder tissues, suggesting that these cells can be used as a tool for studying the mechanisms of gallbladder ion transport both under physiologic conditions and during gallstone formation. 相似文献
979.
Abstract. Adult murine bone marrow cells, cultured under conditions for long-term haemopoietic marrow cultures, produce bone matrix proteins and mineralized tissue in vitro , but only after the adherent stromal cells were loaded on a 3-dimensional collagen sponge. Provided more than 8 × 106 cells are loaded, mineralization as measured by 85 Sr uptake from the culture medium, occurred in this 3-dimensional configuration (3-D) within 6 days. In contrast if undisrupted marrow fragments (containing more than 107 cells) are placed directly on a collagen sponge, then it requires more than 10 days before significant mineralization can similarly be detected. The 2-dimensional (2-D) long-term marrow culture system allows prior expansion of the stromal cells and some differentiation in an osteogenic direction within the adherent stromal layer. This is suggested by the presence of type I collagen and alkaline phos-phatase positive cells. However, synthesis of osteonectin and a bone specific protein, osteocalcin, as well as calcification are only observed in 3-D cultures. Electron microscopy demonstrated hydroxyapatite mineral on collagen fibres, osteoblast-like cells, fibroblasts, cells which accumulated lipids, and macrophages which were retained on the collagen matrices. Irradiation of confluent long-term bone marrow cultures, prior to their loading on the collagen sponge showed that haemopoietic stem cells are not necessary for the mineralization. 相似文献
980.
Cardioprotective effects of erythropoietin in the reperfused ischemic heart: a potential role for cardiac fibroblasts 总被引:23,自引:0,他引:23
Parsa CJ Kim J Riel RU Pascal LS Thompson RB Petrofski JA Matsumoto A Stamler JS Koch WJ 《The Journal of biological chemistry》2004,279(20):20655-20662
Erythropoietin has recently been shown to have effects beyond hematopoiesis such as prevention of neuronal and cardiac apoptosis secondary to ischemia. In this study, we evaluated the in vivo protective potential of erythropoietin in the reperfused rabbit heart following ventricular ischemia. We show that "preconditioning" with erythropoietin activates cell survival pathways in myocardial tissue in vivo and adult rabbit cardiac fibroblasts in vitro. These pathways, activated by erythropoietin in both whole hearts and cardiac fibroblasts, are also activated acutely by ischemia/reperfusion injury. Moreover, in vivo studies indicate that erythropoietin treatment either prior to or during ischemia significantly enhances cardiac function and recovery, including left ventricular contractility, following myocardial ischemia/reperfusion. Our data indicate that a contributing in vivo cellular mechanism of this protection is mitigation of myocardial cell apoptosis. This results in decreased infarct size as evidenced by area at risk studies following in vivo ischemia/reperfusion injury, translating into more viable myocardium and less ventricular dysfunction. Therefore, erythropoietin treatment may offer novel protection against ischemic heart disease and may act, at least in part, by direct action on cardiac fibroblasts and myocytes to alter survival and ventricular remodeling. 相似文献