摘要:

Several chemical effectors were used to induce changes in spleen B cell membrane fluidity. Membrane fluidity was monitored by fluorescence polarization analysis of the hydrophobic probe 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) and cell viability was checked not to be affected by the treatments. Membrane immunoglobulin (Ig) endocytosis by the living B cells with modified or unmodified membranes was quantitatively measured by flow cytometry, using a previously described method (Métézeau et al., 1982, 1984). The kinetics of endocytosis of membrane Ig was not affected by chemical effectors increasing membrane fluidity. On the contrary, increasing membrane microviscosity resulted in the slowing down and eventually the blocking of membrane Ig endocytosis. It is suggested that a step depending on membrane microviscosity is involved in the process of endocytosis; this step may become rate limiting when membranes are artificially rendered or naturally become (i.e. for pathological or particularly differentiated cells) more

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00395.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

In earlier work we have shown that some bacteria bind naturally to lymphocyte subpopulations and that this binding may be due to lectin‐carbohydrate interactions. Here we determined the possibility of using bacteria to probe for these lectins in solubilized tonsil cell membrane preparations. Since lectins are capable of agglutination, we determined the ability of human tonsil cell membrane extract (TCME) to agglutinate bacteria. We used Escherichia coli strain YS57 which does not bind to human lymphocytes and a mutant strain derived from it, E. coli UI 2023, which binds to about 50 percent of human lymphocytes. The UI 2023 was agglutinated while the YS57 was not; this agglutination was not due to antibodies or DNA. When E. coli UI 2023 was treated with periodate, it lost its ability to be agglutinated. The agglutination of E. coli UI 2023 was not blocked by any of the monosaccharides and disaccharides used but was blocked by the E. coli LPS, more specifically, by its carbohydrate moiety. Also, the E. coli UI 2023 absorbed the agglutinating factor while its parental strain, YS57, did not. Sodium dodecylsulfate‐polyacrylamide gel electrophoresis of TCME after absorption with bacteria showed that a band around 67kD was absent in the TCME absorbed by E. coli prevented the absorption by E. coli UI 2023 whereas Na2IO4‐treated LPS did not. In addition, tonsil cell membrane was radioiodinated before obtaining the TCME; sodium dodecylsulfate‐polyacrylamide gel electrophoresis of the radioiodinated TCME recovered after elution from E. coli UI 2023, but not from E. coli YS57, showed again a band around 67 kD.(ABSTRACT TRUNCATED AT 25

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00396.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The shape and the arrangement of subunits in Escherichia coli F1‐ATPase (ECF1) lacking the delta subunit have been explored with a high performance scanning transmission electron microscope. In tilting experiments, the ECF1 molecule appeared as a flat cylinder whose width (approx. 120 A) was about twice its height. The symmetry of front view projections of ECF1 has been investigated by computer analysis. In a population taken at random from the data bank, one third of the particles showed five‐fold radial symmetry components, one third six‐fold radial symmetry components and the last third no typical symmetry. The six‐fold radial symmetry was consistent with a hexagonal arrangement of six large peripheric masses, which probably correspond to the three alpha and the three beta subunits of ECF1. The five‐fold radial symmetry was tentatively explained by a fusion of two juxtaposed peripheric subunits. Lateral projections showed a zig‐zag organization of the large masses, suggesting that the large alpha and beta subunits are located on two levels, with some degree of intercalation between the subunits of the

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00397.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Process of amylase and chymotrypsinogen secretion by acinar cells has been studied applying morphological and biochemical approaches. Three conditions were investigated; resting (fed control), cholinergic stimulation and fasting. Morphometrical evaluations have shown that under stimulation, the volume density of zymogen granules decreases drastically while that of the Golgi apparatus increases. This may result from the enhancement in protein processing and the rapid discharge. Quantitation of amylase and chymotrypsinogen immunolabelings present over the cellular compartments has shown that there is no difference in the intensities between tissues from control and stimulated animals. These results imply that total amounts of protein processed by the Golgi apparatus are markedly enhanced primarily because of the increase in size of the organelle, the amounts of protein processed per unit surface remaining unchanged. Under starvation where reduction of secretion occurs, there is a significant decrease in the volume density of the Golgi apparatus but no variation in that of the zymogen granules. However, the morphological aspect of these was markedly altered since many of them present an electron luscent periphery which was devoid of immunolabeling for amylase and chymotrypsinogen. Quantitation of amylase and chymotrypsinogen immunolabelings has shown significant diminution for both enzymes. In both experimental conditions, the volume density of lysosomes was enhanced, however in none of these conditions evidence of crinophagy was observed. The morphometrical and immunocytochemical results were consistent with those obtained from biochemical determination of amylase and chymotrypsinogen contents in tissues. Correlations between results obtained from morphometric and immunocytochemical studies were made leading to a better understanding of the cellular secretory activity during experimental conditions.

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00398.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The aim of the present study was to test the morphological and functional maturation of recombinants composed of chick intestinal endoderms associated to different mesenchymal supports and their enzymatic response to glucocorticoids. For this purpose 5.5‐day chick embryonic intestinal endoderm has been associated to 14‐day fetal rat gut mesenchyme, to rat intestinal fibroblasts (6‐day neonatal rat intramucosal fibroblasts) or to rat control fibroblasts, originating from 20‐day fetal rat skin and lung and from 6‐day neonatal rat intestinal muscle. The recombinants were grown as intracoelomic grafts either for 12 days or for 10 days plus 2 days in organ culture in the presence of dexamethasone. The data show that heterospecific recombinants achieve subnormal morphogenesis and enzymatic maturation. The organ culture experiments further reveal that sucrase activity is insensitive to dexamethasone in all types of recombinants whereas, alkaline phosphatase is highly stimulated over the levels present in the intestine developed in situ whatever the stromal support, except when this support is provided by rat gut mesenchyme. These results support the view that in the intestine the hormonal response is mediated by epithelial‐mesenchymal i

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00399.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Rat salivary glands were studied by Hanson's method to specify the ultrastructural localization of carbonic anhydrase (CA). Two different procedures were used: 1) The embedding of the tissues in water‐soluble resins, followed by the incubation of the resin sections on the medium. 2) The embedding in epon‐araldite of previously incubated frozen sections. Light and electron microscopy were used to observe the distribution and the ultrastructural localization of the cobalt precipitate. In parotid and mandibular glands, CA was localized in the secretion granules and the hyaloplasma of the secretory endpieces. The enzyme was also detected on the basal and lateral membranes of the striated duct cells in the three glands. In the convoluted granular duct cells of the mandibular gland CA was found in the hyaloplasma only. In the sublingual gland, CA was localized in the hyaloplasma of the serous crescents and no activity was detected in the mucous tubules. As regards the localization of the enzyme in the granules of the secretory endpieces of parotid and mandibular glands, it appears that CA has to be considered as a secretory product of these cells; this localization is consistent with the presence of the enzyme in rat sal

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00400.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Actin distribution in serially passaged embryonic mouse fibroblasts has been visualized by the anti‐actin‐PAP method; the organization of the microfilaments has been observed by electron microscopy (SEM and TEM). Four successive actin patterns have been identified: early (few well‐organized bundles of microfilaments), middle‐aged (many well‐organized bundles and patches around the nucleus), late (numerous ill‐organized filamentous structures and diffuse perinuclear‐actin) and “senescent” (heavy packs of short microfilaments around the nucleus). All the observed actin‐positive filaments were disrupted by cytochalasin B treatment. The cytoplasmic actin complex was cell‐age and not cell‐size‐dependent; it behaved differently from the cytoplasmic microtubular complex to serially subcultivated fibroblasts. Measurements of the cell‐protein content (Lowry's method) and SDS‐polyacrylamide gel electrophoresis (Laemmli's method) have been performed in the successive population doubling levels (PDL) of the primary cultures. Triton‐insoluble actin increased in parallel with total protein and reached about 4% of the total proteins in all the PDLs. Triton‐soluble actin also increase at the beginning of the middle‐aged period (generally 6 PDL) and another in declining cultures (generally 10 PDL). Total actin amounted to about 8% of the total proteins in early fibroblasts, to about 16% at the beginning of the middle‐aged period and to about 20% in the declining terminal cultures. Taking into account all the known characteristics of subcultivated primary cultures, we tentatively consider the evolution of the fibroblasts as an in vitro differentiation followed by true in vitro senescence in the declining cultures. Regarding the cytoplasmic actin‐complex, senescence would be characterized by a sharp increase in soluble actin, an unbalanced ratio between soluble and insoluble actin and an impairment of the ability of the microf

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00401.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Different cytochemical and morphological parameters were used to compare the functional patterns of the erythrocytes in the transition from the trophic (yellow eel) to the reproductive (silver eel) phases of European eel (Anguilla anguilla L.). Data on the nucleus were obtained by microdensitometric (Feulgen reaction) and cytofluoremetric (propidium iodide and Hoechst 33342 fluorochromization) evaluations of DNA staining intensity. In the silver eel, chromatin condensation was more heterogeneous and chromatin also appeared to be looser. The fluorochromes provided information on the different degrees of organization of the chromatin filament, with regard to both primary and higher order DNA structure. In the silver eel, the fine structure showed a higher number of erythrocytes with large euchromatinic areas and the heterochromatinic component was occasionally present in scattered clumps. As for the cytoplasm, in the silver eel a positive correlation could be established between the presence of intact cytoplasmic organelles (mitochondria, Golgi complexes, ribosomes, etc.) and the high fluorescence intensity. This aspect is revealed through the detection of definite membrane components such as glycoconjugates and primary amino groups (PAS reaction and fluorescamine staining, respectively). All these findings allowed us to establish that the transition from the trophic to the premigratory reproductive phase is marked by a higher heterogeneity of the erythrocytes, due to different cell maturation levels. This fact can be ascribed to different metabolic requirements as well as to a more intense erythropoiesis, typical of the most active phase of the eel's life.

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00402.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY