摘要:

AbstractThe amount of Na+, K+‐ATPase of the avian salt gland increased concomitantly with plasma membrane surface area during salt feeding of ducklings (adaptation), and both enzyme content and membrane surface area decreased upon return to fresh water (deadaptation). In a further study of the enzyme, a marker for plasma membrane biogenesis, polyvalent antibodies were raised to the denatured α‐subunit of the purified ATPase. Antisera did not inhibit enzymatic activity but immunoprecipitated the phosphorylated intermediate of the α‐subunit. Furthermore, the α‐subunit, which was not glycosylated, was immunoprecipitated from homogenates of tissue slices metabolically labelled with [35S]‐methionine, using antisera raised against either duck salt gland or dog kidney α‐subunit. The former antisera also recognized the α‐subunit in the brain, heart, kidney, liver, intestine and skeletal muscle of the duck.Immunocytochemistry with the antisera raised to the duck salt gland α‐subunit revealed reaction at basolateral as well as apical plasma membrane in the duck salt gland principal cells, with essentially no deposits no deposits on peripheral cells, fibroblasts, erythrocytes, endothelial cells and neural elements. Within the principal cells, immunolabelling was also detected on small vesicles, multivesicular bodies and lysosomes; deposits on extracellular debris and vesicles in the lateral and lumenal spaces were also apparent. The labelling patterns were qualitatively but not quantitatively similar in salt glands of control, adapted and deadapted ducklings, and are discussed in the context of a model for plasma membrane biogenesis and turnover in which degradative events

ISSN:0263-6484    

DOI:10.1002/cbf.290050102

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe activities of two phosphatases (E. C. 3.1.3.1 and 3.1.4.1) and four glycosidases (E.C. 3.2.1.21, 3.2.1.30, 3.2.1.31 and 3.2.1.51) were measured by fluorescence spectrophotometry, and flow cytometry, in mitogenstimulated lymphocytes, and in cultures of Molt‐4‐F and F‐89 cell lines, syncronized by hydroxyurea or thymidine.All enzymes were active throughout the cycle but the activities of three enzymes were elevated at specific points in the cycle, alkaline phosphatase activity increased at G2+ M/G1boundary and in early S‐phase, the activity of β‐Lfucosidase was elevated in G1and late S‐phase. Orthophosphate diesterase activity was elevated at the G1/S boundary, and during G2+ M. The increase in β‐Lfucosidase activity was due to an increased number of cells showing activity, whilst the increase in orthophosphate diesterase activity was attributable to an increase in cellular enzyme activity.Only the activities of orthophosphate diesterase and β‐Lfucosidase were measurable by flow cytometry, alkaline phosphatase activity was mainly extracellular, and therefore not detectable by flow cytometri

ISSN:0263-6484    

DOI:10.1002/cbf.290050103

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe addition of butyric acid to murine erythroleukemic cells (clone T3C12) induced the cells to differentiate, producing adult hemoglobin (A, α2,β2) and an embryonic hemoglobin (E2, α2Y2). The subsequent addition of hemin to the differentiating cells increased the synthesis of adult hemoglobin four‐fold and the synthesis of embryonic hemoglobin two‐fold; the relative synthesis of the α and β globins increased more than the Y globin. The embyronic hemoglobin was expressed prior to the adult hemoglobin in differentiati

ISSN:0263-6484    

DOI:10.1002/cbf.290050104

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractWe have studied calcium movement from blood into the bile by injecting45Ca2+intravenously and measuring the radioactivity appearing in the bile.45Ca2+started to appear in the bile at 3 min and maximum values were observed at 5 min after its administration. The amount of calcium secreted into the bile was proportional to the blood calcium concentration indicating that the main pathway involved in calcium movement behaved as a non‐saturable system.We have also studied the45Ca2+circulation from blood into the bile in rats subjected to a partial hepatectomy. Thereafter, the calcium transported into the bile per gram of liver increased by about 50 per cent. Since bile flow behaved in a similar way, the biliar calcium concentration remained unmodified after hepatectomy.Determination of the activities of the Ca2+transporting systems in isolated plasma membrane fractions from regenerating livers showed no modification in these activities suggesting that the elevation in calcium movement observed after hepatectomy is not due to an increase in the circulation of Ca2+through the transhepatocyte pathway, an observation compatible with the absence of saturation in the transpor

ISSN:0263-6484    

DOI:10.1002/cbf.290050105

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractA technique is described for isolation of adult rat hepatocytes from micronodular cirrhotic livers based on a collagenase digestion procedure. Hepatocytes from normal livers and those chronically injured by thioacetamide did not differ with respect to the viability measured by the trypan blue exclusion test or to the cellular concentrations of protein and glycogen, but the triglycerde content of cells from cirrhotic livers was significantly reduced. Hepatocytes isolated from cirrhotic livers are ultrastructurally in a good state of preservation but they appear to be poorer than controls in RER membranes, although the well‐preserved mitochondria are somewhat richer in cristae. No differences were detected between the cell preparations in rates of gluconeogenesis and totalde novofatty acid synthesis, but the secreation of newly synthesized fatty acids was significantly reduced in cells from cirrhotic livers.Thus adult rat hepatocytes can be isolated from thioacetamide‐induced micronodular cirrhotic livers with high yield and morphological integrity. Differentiated functions are maintained in suspension for at least

ISSN:0263-6484    

DOI:10.1002/cbf.290050106

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe fluorescence probe 1,6‐diphenylhexa‐1,3,5‐triene (DPH) was used for monitoring structural perturbations induced by lipopolysaccharide (LPS) ofEscherichia coli(0111 : B4) in plasma membranes of rat liver. Changes in microviscosity were observed in plasma membrane preparations from control rats after treatment with LPS and in plasma membrane preparations from liver perfused with LPS. In both systems fluorescence polarization was measured from which microviscosity was calculated. This parameter increases with LPS treatment. From temperature dependence studies was inferred that LPS interaction with plasma membrane preparations induces an increase of both the polarization term (r0/r–1)−1and flow activation energy (ΔE). Addition of LPS to hepatocyte suspensions also induces an increase on microviscosity and a delay in the fall of microviscosity induced by a temperature rise in hepatocyte monolayers grown on microcover slides.These data suggest that LPS interaction can be attributed to its binding to membrane hydrophobic regions in a non‐spe

ISSN:0263-6484    

DOI:10.1002/cbf.290050107

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe binding of [125I]‐human growth hormone (hGH) was studied in epithelial cells isolated from rat ventral prostate. Binding and degradation were dependent on time and temperature. The effect of a lysosomotropic agent suggested internalization and lysosomal degradation of the hormone. Dissociation and stoichiometric studies indicated the existence of a single class of GH receptors with aKdof 0·7 nM and a binding capacity of 46 fmol hGH bound mg−1cell protein. The receptor appeared to possess a somatotrophic nature since lactogenic hormones such as human placental lactogen and rat prolactin exhibited a very low degree of competition (whereas a variety of unrelated hormones and neuropeptides showed no effect). GH‐stimulated leucine uptake by the cells in a time‐ and dose‐dependent manner, half maximal effect being observed at 0·32 nM GH thus suggesting a direct relationship with the b

ISSN:0263-6484    

DOI:10.1002/cbf.290050108

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractIn order to define the importance of the mucosal uptake step in the intestinal regulation of iron absorption, unidirectional uptake rates of Fe3+from a nitrilotriacetic acid chelate were measured in duodenal fragments from mice using anin vitrotechnique. [57Co]‐Cyanocobalamin was used as a marker of adherent incubation medium. Uptake showed saturation kinetics over the concentration range 18–450 μM. Uptake was increased in fragments from hypoxic, dietary iron‐deficient and pregnant mice. The enhanced uptake was due to an increase inVappmax. However, the modest increase in uptake rates in pregnancy and the gross changes observed in iron‐deficiency make the hypoxic model the most convenient. The increase in uptake in hypoxic animals was located to the duodenal region and was not associated with changes in either total mucosal iron content or epithelial cell turnover. The rate of uptake of iron via the serosa did not change with hypoxia. This study implies that flux of Fe3+across the brush border is subject to adaptive regulation. The hypoxic model is suitable for investigation into the regulation of iron ho

ISSN:0263-6484    

DOI:10.1002/cbf.290050109

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290050112

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290050114

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY