摘要:

Rotation‐mediated aggregate cultures of foetal rat liver cells were prepared and grown in a chemically defined medium. Their capacity for cellular organisation and maturation was studied over a culture period of 3 wk by using both morphologic and biochemical criteria. It was found that within each aggregate, distinct liver cell types were present and attained their normal, differentiated phenotype. Parenchymal cells formed small acini with a central lumen. Within the first 2 wk in culture, albumin and ferritin mRNA levels were maintained, while the alpha‐fetoprotein mRNA levels decreased, and tyrosine aminotransferase (TAT) gene expression increased. No significant response to glucocorticoids was observed in early cultures, whereas after 3 wk a marked increase in TAT mRNA levels was elicited by dexamethasone and glucagon (additive stimulatory effects). The results show that foetal rat liver cells cultured in a chemically defined medium are able to rearrange themselves into histotypic structures, and display a developmental pattern of gene expression comparable to that of perinatal rat liver in vivo. This culture system offers therefore a useful model to study the development and function of liver ce

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00555.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

When individuals of Drosophila subobscura at 0 hr prepupa are submitted to anoxia (4 hr and 24 hr, respectively), their puffing pattern is very similar to that shown by individuals at the moment of development in which treatment began. The same expression of genes (the same puffing pattern and the same protein pattern) is induced in this species by recovery from anoxia as well as by heat shock treatment at 31 degrees C.

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00556.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

We have identified and characterized a membrane glycoprotein located at the apical plasma membrane of adult human colon epithelial cells, by the use of the monoclonal antibody technique in combination with immunocytochemical and biochemical methods. Analysis of membranes extracted with Triton X‐114 and treated with specific hydrolases indicated that the antigen was an integral membrane glycoprotein. In the colon, the antigen was expressed in differentiated cells and along the entire crypt. It was also expressed at the apical membrane of the crypt cells of the distal ileum. It was not found in the proximal ileum, jejunum, or duodenum. In contrast, the antigen was found in all segments of the intestine of a 24‐week‐old embryo. Furthermore, the antigen had different apparent molecular weights in the adult ileum (200 kDa), adult colon (200 kDa and 301 kDa), and embryo (170 kDa). Therefore, this antigen should prove to be a useful marker to study the appearance of epithelial cell polarity during embryoge

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00557.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

We studied mechanisms that mediate recognition of human erythrocytes (HRBC) and sheep erythrocytes (SRBC) by rat liver macrophages. We used an in vitro cell binding assay that allows spontaneous formation of cell contacts. Binding of HRBC to rat macrophages shows the following characteristics: inhibition studies with several monosaccharides and oligosaccharides yield complete inhibition of cell contacts with saccharides, which block the GalNAc/Gal‐particle receptor on rat liver macrophages. We found the inhibition pattern: N‐acetyl‐D‐galactosamine, lactose greater than D‐galactose, D‐fucose greater than L‐fucose much greater than N‐acetyl‐D‐glucosamine. Cell binding is dependent on the presence of calcium ions, but not influenced by heat‐aggregated IgG or gangliosides. The inhibition pattern was the same after treatment of HRBC with neuraminidase. Therefore, binding of HRBC, as well as binding of neuraminidase‐treated HRBC, is mediated by the GalNAc/Gal‐particle receptor. Binding of SRBC is partly inhibited by galactose‐related saccharides. Binding is also partly inhibited by heat‐aggregated IgG, gangliosides, and L‐fucose. Complete inhibition of cell contacts with SRBC is achieved by combination of all inhibitors. We therefore conclude that binding of SRBC is mediated by several different mechanisms, including the GalNAc/Gal‐particle receptor. Binding of neuraminidase‐treated SRBC, however, was found to be completely inhibited by saccharides, which block the GalNAc/Gal‐particle receptor. We conclude that the GalNAc/Gal‐particle receptor mediates or participate

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00558.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Incorporation of [3H]glucosamine into dispersed anterior pituitary cells was studied by electron microscope autoradiography. Gonadotrophs were examined to determine the intracellular route and kinetic patterns of glycosylation. Studies were performed with cells from; (a) normal adult male rats; (b) rats orchidectomized 3 wk earlier; and (c) orchidectomized rats treated with tunicamycin. Our results show that incorporation of [3H]glucosamine first occurs in the rough endoplasmic reticulum (RER), then proceeds in the Golgi elements (where peripheral carbohydrates are attached). Treatment with tunicamycin results in a decrease in labeling of these 2 organelles. Comparison of the kinetic patterns in normal and castrated male rats shows that the accumulation of labeled glycosylated proteins in granules reaches a plateau within 2 hr post‐pulse in normal rats, and rises during a 6‐hr chase in castrated rats. However, because of the necessity for a rather long 15 min pulse, we cannot exclude the possibility that incorporation of glucosamine during the pulse may occur concomitantly in the RER and the Golgi saccules, to be followed by rapid transfer to the secretory granu

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00559.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The role of Ca2+‐ATPase as the driving force for active calcium uptake, involved in the relaxation of smooth muscle, was studied. It was shown by immunocytochemistry that Ca2+‐ATPase activity was localized at the plasma membrane level of longitudinal smooth muscle of pregnant rat uteri (18‐20 days). To study calcium regulation in uterine longitudinal smooth muscle, 2 microsomal fractions (F1 and F2) were obtained, enriched in plasma membrane material (Lalanne et al., 1984, in: Calcium Regulation in Smooth Muscles. INSERM series, 124, pp. 283‐292). In the present paper this material is characterized at both morphologic and cytochemical levels. Both fractions are ultrastructurally heterogeneous: (a) thin sections clearly show 2 populations that differ in vesicular shape and size; (b) negative staining also shows differences in membrane structure, which could be related to biochemical differences and/or to the well known heterogeneity of the plasma membrane. Two reactions (PATAg and concanavalin A‐biotin‐avidin‐ferritin), allowing visualization of cell coat glycans, were performed on F1 and F2 and on thin sections of longitudinal smooth muscle. Plasma membrane and almost all the vesicles of F1 and F2 are reactive. It is concluded that these 2 fractions are characteristic enough for studying, at the molecular level, the ability of plasma membrane to control calcium circulation in uterine

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00560.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Time‐dependent frequency distribution of binucleate cells (BC) was studied in Ehrlich ascites tumor (EAT) growing in mice. In animals that received no further treatment, the number of BC increased slowly from 2.6% to 16.5% of total cells within 8 days. In animals that were treated with different doses of 5‐fluorouracil (FU) we found clearly higher numbers of BC. The number of BC increased with tumor age. The increase observed after treatment was reached more quickly in animals that had received the highest FU dose. The final number of BC was also dependent on the age of the tumor at the time of FU inject

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00561.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY