摘要:

A monoclonal antibody of the IgG2a subclass was isolated from the supernate of a hybridoma line obtained with splenocytes from a mouse immunized with a crude nucleolar fraction of human Namalwa cells. This antibody identifies a single nuclear polypeptide antigen characterized by: (a) presence in proliferating human cell lines and phytohemagglutinin‐stimulated lymphocytes, but absence in resting lymphocytes; (b) appearance in stimulated lymphocytes in parallel with the onset of DNA synthesis; (c) a speckled distribution in the nucleoplasm; (d) tight association with nuclear matrix structures identified by both biochemical and in situ extraction and enzyme treatment procedures; (e) mol wt of 125 kDa and pI 6.5 as determined by immunoprecipitation or immunoblotting of nuclear or nuclear matrix proteins fractionated by gel electrophoresis. The above characteristics identify the p125/6.5 nuclear matrix protein recognized by the isolated monoclonal antibody as belonging to the class of proliferating cell nuclear antigen

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00539.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Quantitative changes in the size of pinealocyte nucleoli have been reported in various studies on this cell type. However, the significance of quantitative changes in the nucleolar components is unknown. The present study is an attempt to analyze ultrastructural and morphometric modifications occurring in the pinealocyte nucleolar components during the estrous cycle in female rats. The fibrillar centers showed an increase during estrus consistent with a decrease in pinealocyte nucleolar activity and melatonin pineal levels. The fibrillar components and granular components tended to display a reciprocal relationship. An increase in the dense fibrillar component took place at metaestrus and diestrus when melatonin synthesis increased in pinealocytes. Maximum values of granular and interstitial components were found at the proestrus phase before the day of ovulation.

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00540.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Electron microscopy of ultrathin serial sections has been used to study the origin and fate of a mass of fibrillar material (FM) during spermatogenesis in the wood lemming Myopus schisticolor. In the course of early pachytene, one of the two nucleoli completely disappears. The remaining nucleolus loses its granular portion and acquires a “round body” encased by the fibrillar moiety, and the restructuring is accompanied by the appearance of FM in the close vicinity of this nucleolus. During diakinesis, the FM increases in volume and density and selectively infiltrates the chromatin of the XY pair. The intermingling of sex chromosomes and FM is at its maximum in metaphase I, giving the XY chromatin a patchy appearance. The FM separates along with the chromatin during the ensuing anaphase I and is shed from the chromosomes during early telophase I. By the time the nuclear envelope is reconstituted, the FM is completely separated from the chromatin. It disintegrates in the spermatids. The FM could not be stained using the Ag‐NOR technique. In the wood lemming, X and Y chromosomes show an end‐to‐end association without a detectable synaptonemal complex. The FM may contribute to the attachment of the two sex chromosomes to each other. Thus, the FM is considered to be a substitute for a chiasma, which normally guarantees proper segregation in a

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00541.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The structural organization of Ectromelia virus DNA in infected mouse liver cells has been studied by using thin sections stained with the Feulgen‐like osmium‐ammine reaction. We found that in the cytoplasmic factories, free viral DNA was structured into completely extended filaments 2‐3 nm thick. Viral DNA in immature virions, however, appeared to have a structural organization that superimposed that of eukaryotic chromatin. This was constituted by roundish subunits, with a diameter of 11‐13 nm, composed of a DNA ring encircling an unstained inner core. The mature virion was composed of the same type of subunits, which were arranged in threads twisted into a figure 8 configuration. The distribution of basic proteins was also investigated with the acrolein silver‐methenamine technique. In the viral particles only nucleoids were stained; a uniformly distributed positive reaction was observed in the cytoplasmic

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00542.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The morphology and ultrastructure of B16 melanoma cells was examined after treatment of the cells with the chemical inducers of differentiation dimethylsulfoxide (DMSO), butyric acid, and dimethylthiourea (DMTU). The treated B16 melanoma cells seemed to be enlarged and more flattened, and to possess dendrite‐like structures as revealed by scanning electron microscopy. The main ultrastructural features, depicted by transmission electron microscopy in DMSO‐treated B16 cells were: a marked increase in melanin granules, migration of the melanin granules to the dendrites, and appearance of melanosome aggregates. Butyric acid did not induce melanin biosynthesis; however, it stimulated rough endoplasmic reticulum (RER) formation all over the cytoplasm. The DMTU‐treated cells also showed a well developed RER accompanied by early stages of melanosomes and melanin granules. The increase in the endoplasmic reticulum was also reflected by enhancement of NADPH cytochrome c reductase activity, an enzymatic marker of the endoplasmic reticulum. The mitochondria in the DMTU‐treated cells were swollen with disrupted cristae. The results indicate that DMSO, butyric acid, and DMTU induce different ultrastructural patterns in B16 melanoma cells. These findings correlate with the biochemical alterations induced in melanoma cells by these

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00543.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The expression and cytochemical localization of alkaline phosphatase and Na+‐pump sites were investigated in the human adenocarcinoma cell line HT‐29.18 during differentiation. In the undifferentiated state, HT‐29.18 cells expressed ATPase activity on plasma membrane whereas they displayed no alkaline phosphatase activity. In differentiated HT‐29.18 cells, strong alkaline phosphatase activity was present on the apical membrane, whereas ATPase activity was restricted to the basolateral membrane. Intra‐ and intercellular lumina (cysts) observed in undifferentiated cells were devoid of both enzyme activities. In differentiated cells, cysts bearing well developed microvilli were strongly positive for alkaline phosphatase activity, while this activity seemed to be lacking in cysts without microvilli. ATPase activity was not found in either type of structure. Finally, HT‐29.18 differentiated cells expressed, at pH 9.0, a p‐nitrophenylphosphatase activity six‐fold greater than that of undiffe

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00544.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The distribution of basement membrane glycoproteins (type IV collagen, laminin, fibronectin, and proteoglycans) was studied in foetal rat kidney by immunohistochemical techniques using polyclonal antibodies. From the first stages of nephron differentiation, all these glycoproteins were detectable by immunofluorescence in the tubular and glomerular basement membranes and in the mesangial matrix. As differentiation proceeded, labelling of glycoproteins progressively intensified, except for that of fibronectin, which gradually decreased in the glomerular basement membrane (GBM) and was barely observable at full differentiation. With immunoperoxidase staining in electron microscopy, all glycoproteins were seen to be widely dispersed in the spaces between the epithelial and endothelial glomerular cells so long as the GBM remained a loose structure. However, after it became a compact, 3‐layered formation, type IV collagen and laminin were distributed throughout the GBM, whereas proteoglycans and anionic sites appeared as 2 rows of granules confined to the laminae rara

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00545.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The localization of actin in the cells of the pars intermedia of rat hypophysis was studied by means of the polyethylene glycol (PEG) embedding and subsequent de‐embedding method together with FITC and IgG‐colloidal gold immunolabelling techniques. Actin immunofluorescence was detected to be punctate throughout the entire cytoplasm, except for the nuclear region. In electron microscopy actin gold‐labelling was localized on portions of microtrabeculae in close association with the secretory granules, but not within the secretory granules themselves. This close association of actin with the secretory granules strongly suggests the involvement of the contractile protein in the cellular secretory process. Several restrictions due to the PEG‐method itself are also discussed to interpret clearly immunoelectron microscope images from the embedment‐free

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00546.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Unfertilized Paracentrotus lividus egg cytoskeleton is prepared by mild, nonionic detergent extraction at 4 degrees C in buffer systems containing either 2‐methyl‐2,4‐pentanediol (hexylene glycol) or glycerol. These extractions allow the isolation of cytomatrices that maintain the egg form and are 70‐80 micron in diameter. DNase inhibition assays show that actin is in polymerized form in these cytomatrices. Ultrastructural observations reveal that the cytoskeletons are made up essentially of 2 categories of filaments, 7‐8‐nm and 2‐4‐nm in diameter, respectively. After heavy meromyosin labelling, short, radiating actin filaments are seen in the cortical region, while longer actin filaments are found in the internal region of these cytomatrices. The 2‐4‐nm filaments of still unknown biochemical nature are organized in a meshwork. In contrast to results found with fertilized eggs, bundles of actin filaments and microtubules are absent; 8‐13‐nm fil

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00547.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Using Immunoblotting procedure, we showed that autoimmune human antibodies reacting with mouse retrovirus gag‐p30 also reacted with a HnRNP 68 Kd protein. Since U1‐SnRNP 68 K and p30‐gag proteins show 40% homology, the detected 68 Kd protein is likely to be the U1‐R

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1987.tb00548.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY