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1.
The l-thyroxine binding site in human serum thyroxine-binding globulin was investigated by affinity labeling with N-bromoacetyl-l-thyroxine (BrAcT4). Competitive binding studies showed that, in the presence of 100 molar excess of BrAcT4, binding of thyroxine to thyroxine-binding globulin was nearly totally abolished. The reaction of BrAcT4 to form covalent binding was inhibited in the presence of thyroxine and the affinity-labeled thyroxinebinding globulin lost its ability to bind thyroxine. These results indicate BrAcT4 and thyroxine competed for the same binding site. Affinity labeling with 2 mol of BrAcT4/mol of thyroxine-binding globulin resulted in the covalent attachment of 0.7 mol of ligand. By amino acid analysis and high voltage paper electrophoresis, methionine was identified as the major residue labeled (75%). Lysine, tyrosine, and histidine were also found to be labeled to the extent of 8, 8, and 5%, respectively. 相似文献
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Flow cytometry: rapid biochemical analysis of single cells 总被引:7,自引:0,他引:7
H S Kruth 《Analytical biochemistry》1982,125(2):225-242
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The results of a detailed analysis of 100 supernumerary limbs generated by 180° ipsilateral rotation (on the same limb stump) of regeneration blastemas is presented. The limbs were analyzed in terms of their position of origin, frequency, cartilage structure by Victoria blue staining, and muscle structure by serial sections. Single, double, or triple supernumeraries can be produced at no unique position of origin, although the posterodorsal quadrant was preferred. Four classes of supernumerary limbs were generated by such operations—normal; double dorsal or double ventral; part normal/part mirror imaged; part normal/part inverted in approximately equal frequencies. After amputation of these supernumeraries the same muscle patterns are faithfully regenerated. A hypothesis to explain the production of these abnormal limbs is proposed based on the observed phenomenon of fusion of supernumerary blastemata, but their regenerative behaviour presents problems for current models of pattern formation. Similar results have been obtained with developing limb buds and the relation between development and regeneration is discussed. 相似文献
6.
In vitro growth of murine T cells. IV. Use of T-cell growth factor to clone lymphoid cells 总被引:3,自引:0,他引:3
Murine bone marrow cells can suppress the in vitro primary antibody response of normal spleen cells without apparent cytotoxicity. The bone marrow cells suppress the response to both T-dependent (SRBC) and T-independent (DNP-Ficoll) antigens. When bone marrow cells are fractionated on a sucrose density gradient, the suppressive activity is found in the residue rather than the lymphocyte fraction. The suppressive activity is either unaffected or enhanced by treatment with anti-T- and anti-B-cell serums. Pretreatment of mice with phenylhydrazine which reduces the number of pre-B cells did not reduce the suppressive activity of their bone marrow cells. Suppressive activity is abolished by irradiation of the marrow cells in vitro with 1000 R prior to assay. The activity is present in the marrow of thymus deficient (nude) mice, infant mice, and mice which have been made polycythemic by transfusion. Furthermore, the suppressor cell can phagocytize iron carbonyl particles, is slightly adherent to plastic and Sephadex G-10, and can bind to EA monolayers. We conclude that the suppressor cell is not a mature lymphocyte or granulocyte nor a member of the erythrocytic series, but is likely to be an immature cell possibly of the myeloid series. We speculate on the physiologic role of this cell. 相似文献
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Anton Pauw Sunshine A. Van Bael Halton A. Peters Steven D. Allison José L. C. Camargo Miguel Cifuentes-Jara Aurlstela Conserva Teresa Garcia Restom Tamara Heartsill-Scalley Scott A. Mangan Gabriela Nunez-lturri Elsie Rivera-Ocasio Mark Rountree Susanne Vetter Carolina Volkmer de Castllho 《Biotropica》2004,36(3):410-413
9.
Celia Gluzman de Pascar 《Hydrobiologia》1987,144(2):125-130
The Oligochaeta of some streams flowing into the Rio de La Plata, Buenos Aires, Argentina, were investigated. Twenty nine
taxa (twenty four naidids, five tubificids) were identified. Most species are cosmopolitan, but Dero evelinae, Pristina leidyi, Slavina isochaeta and Bothrioneurum sp. are neotropical. Bratislavia unidentata, Haemonais waldvogeli and Nais pardalis are reported for the first time in Argentina. Variants occurr in the shape of the distal end of the penial sheaths of Limnodrilus hoffmeisteri. The dominant Naidid genera are Dero and Pristina. In the polluted El Gato stream only L. hoffmeisteri and L. claparedeianus were found. 相似文献
10.
The germination response to NaCl treatments has been studied in Melilotus seed populations collected from saline and non-saline
soils in the Guadalquivir delta.
The rank orders for salt tolerance and seed weight were the same in the threeMelilotus species living in this area:Melilotus messanensis>M. segetalis>M. indica.
Within the species, differences in germination response to salinity were found inM. indica (6 populations) andM. segetalis (8 populations). The relationship between salt tolerance during germination and salinity of maternal habitat is discussed. 相似文献