摘要:

ABSTRACTCiliate encystment is an eukaryotic cell differentiation process which involves a specific gene expression, to form the resting stage. In this study, we investigate, for first time, the DNA methylation pattern changes during encystment in the ciliate Colpoda inflata, and the 5‐azacytidine effect on growing cells and encystment. Results indicate that 5‐methylcytosine is present in macronuclear DNA of this ciliate and the 5‐azacytidine treatment induces encystment in growth conditions. From restriction enzyme digestion and 5‐azacytidine experiments, we conclude that a specific DNA demethylation is probably involved in the encystment gene expression of this

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1067

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe mdx mouse has been used as an animal model for human Duchenne muscular dystrophy (DMD). Unlike DMD, skeletal muscles of mdx mice undergo successful regeneration and do not show extensive fibrosis and functional impairment. Growth factors have been proposed to be involved in muscle growth and regeneration. We compared mitogenic activity for skeletal myoblasts released after injury in mdx and control mice, using crushed muscle extract (CME) as a model system. We found that CMEs from normal and mdx mice contained similar mitogenic activities per microgram protein, and produced similar maximal levels of mitogenic stimulation. Skeletal muscles from mdx mice, however, released higher amounts of CME protein per gram of muscle weight compared to controls, possibly as a result of histological or physiological alterations in mdx muscle tissue. Adequate mitogenic activity in CME from mdx muscles may be related to successful muscle regeneration in mdx mice.

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1068

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe radioprotective effect of the bacterial immunomodulator Nocardia delipidated cell mitogen (NDCM) on intestinal mucosa and disaccharidase activities was studied in irradiated germ‐free piglets. Three‐week‐old germ‐free (GF) piglets were intragastrically pretreated with 1 mg NDCM per 1 kg body weight. The piglets were whole‐body irradiated with 2.5 Gray five days after the NDCM pretreatment and sacrificed eight days after irradiation. In the non‐irradiated group of GF piglets, NDCM application stimulated lactase activity and markedly increased sucrase activity. This stimulatory effect of NDCM disappeared after irradiation and the piglets exhibited a normal activity of lactase in the jejunal brush‐border membrane vesicles, while the sucrase activity decreased to the level found in irradiated controls. NDCM‐pretreated intestinal mucosa contained some infrequent lymphocytes which disappeared from the control irradiated tissue. It also exhibited less injury of the epithelium a

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1069

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe replication state of rDNA in testes nuclei undergoing polyploidization by classical‐type endomitosis was investigated in Gerris najas (Heteroptera) by means of fluorescence in situ hybridization. The number of just one rDNA locus per haploid genome was determined by in situ hybridization on meiotic nuclei. Additionally, DNA measurements of spermatids and testes nuclei were performed. Although regular duplication levels of nuclear DNA were found within the limits of the accuracy of the method, these did evidently not apply to the ribosomal genes. The comparison of the number of rDNA signals with the DNA content of 106 testis nuclei revealed drastic variations of the number of rDNA loci between individual nuclei with similar DNA content. Polyploid nuclei of the testis epithelium showed too low numbers of rDNA loci in relation to those expected from the levels of ploidy, while cyst cell nuclei displayed increased numbers of rDNA loci. The results indicate that the ribosomal genes are either underreplicated, or in part eliminated, during the endomitotic cycles of epithelium cell nuclei, but amplified in the cyst cell nuclei, probably already at their diploid stag

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1070

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTIn previous studies a novel lectin‐like glycoprotein was isolated from silkworm faeces and shown to recognize sugar chains, especially mannose on the cell surface as an epitope, and to cause aggregation of various types of cells in suspension. However, this substance caused detachment and aggregation of only some types of plated cells, such as QM‐RSV cells, which are quail myoblasts transformed with a temperature‐sensitive mutant of Rous sarcoma virus (ts‐RSV) at 35.5 °C, a permissive temperature for RSV. As described here, during studies on the mechanism of cell detachment and aggregation of QM‐RSV cells by this new lectin, some novel biological activities of the lectin were recognized. This lectin was found to bind to immunoglobulins (Ig) specifically at specific amino acid sequences, not via recognition of their molecular conformation. It also recognized the neural cell adhesion molecule (NCAM), which is one of the members of the Ig‐superfamily that have Ig‐like domains. Furthermore, it had a strong mitogenic effect on lymphocytes, and also caused about 3‐fold of phagocytosis by macrophages within 24 hr af

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1071

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe effects of aphidicolin, a specific inhibitor of DNA polymerase α, on cell growth, DNA synthesis and myogenic differentiation in the human alveolar rhabdomyosarcoma cell line KFR were studied. The treatment with aphidicolin at 5 × 10−6M concentration, which completely inhibited DNA synthesis and cell growth, induced morphological differentiation of small mononuclear cells to elongated, multinucleated (myotube‐like) structures. The morphological differentiation was accompanied by the expression of skeletal muscle myosin; about 30% myosin‐positive cells were observed after 14 days of treatment, compared to 2.3% in untreated cultures. The results showed that aphidicolin induces differentiation of human rhabdomyosarcoma cells and that multinucleated myotube‐like elements may develop simply by cell fusion without cell division and DNA

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1072

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTZinc movement across eel and human red blood cell membranes was measured by atomic absorption spectrophotometry. It was observed that:1)In human red blood cells zinc uptake is twice as rapid as in fish red blood cells over a temperature range of 10‐40°C. The low rate of zinc uptake in eel red blood cell may be simply the side effect of different surface area to volume ratios for the differences in cell size or, it may be due to the low permeability of bicarbonate through the red blood cell membranes.2)Zinc uptake measured in eel and human red blood cells treated and untreated with external trypsin shows different features. The zinc uptake was reduced by about 40% in treated eel red blood cells with respect to the total uptake of untreated red blood cells. Human red blood cells treated and untreated with trypsin do not show any differences in the amount of zinc transported.3)In fish red blood cells, zinc uptake in NANO3medium is markedly reduced, compared with that measured in NaCl medium. The [Zn2+islightly increases in the presence of bicarbonate. In human red blood cells in NANO3medium the zinc uptake is strongly reduced and the presence of bicarbonate marginally increases the zinc influx.4)In eel red blood cells there seem to be two independent pathways for zinc uptake: one DIDS‐sensitive and the other DIDS‐insensitive. DIDS 10 μM inhibits only 64% of the total zinc transported. Iincreasing the DIDS concentration did not give more inhibition. In human red blood cells only one DIDS‐sensitive pathway for zinc transported seems to exist, because, 2,5 μM DIDS inhibits 97% of z

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1073

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1074

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1075

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1076

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY