ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Cell & Developmental Biology  (5)
Collection
Publisher
Years
  • 1
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It was shown previously that mouse bone marrow cells transformed by simian virus 40 (SV40) show a reversible cell density-dependent phenotypic transition between the nonmacrophage (rapidly growing) and the macrophage (stationary) states; cells in low-density cultures are in the growing phase, express SV40 T antigen strongly as revealed by immunofluorescence, and lose typical macrophage properties such as immune phagocytosis; whereas cells in high-density cultures are in the stationary (nongrowing) phase, express SV40 T antigen weakly, and recover their macrophage properties (Takayama, 1980). In the hope of clarifying the relationship between T antigen, cell growth, and macrophage-specific cellular function, we examined the behavior at 33 and 39°C of mouse bone marrow cells transformed by an SV40 gene A mutant (tsA640) whose mutation renders the molecular weight of 90K (large) T antigen temperature sensitive. The results presented in this paper suggest that functional large T antigen is required for cells in the stationary phase to initiate multiplication when transferred at lower density and is not necessary for a majority of them to maintain the nongrowing state (viability) at both high and lower cell densities, whereas it is required for cells in the growing phase to keep multiplying without losing their viability. The results also suggest that the functional large T antigen does not play a direct role in maintaining the cells as either phagocytic or nonphagocytic. It is also suggested that the physiological or tsA mutation-mediated arrest of growth may or may not be accompanied by induction and/or maintenance of cellular phagocytic activity depending on the culture state.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultures of mouse macrophage cell lines transformed by wild-type or the tsA640 mutant of simian virus 40 (SV40) show a reversible phenotypic transition between the nonmacrophage (proliferating phase) and the macrophage (stationary phase) states (Takayama, 1980; Tanigawa et al., 1983). Distribution of DNA content in the cultures of the tsA640-transformed macrophage lines in the process of the phenotypic transition was determined by flow cytometry. Taking the mean DNA content of mouse peritoneal macrophages as 1 unit in the scale of fluorescence intensity in the flow cytogram, the transformed macrophages showed, at 33°C, two peaks, one located around the 1.0-unit position (peak 1.0) and the other around the 1.6-unit position (peak 1.6), and a plateau distribution continuing to 3.2 units. Peak 1.0 was predominant in the stationary-phase culture, whereas peak 1.6 was predominant in the proliferating-phase culture. Almost the entire population of the strictly resting culture, which was obtained by culturing the stationary-phase culture for a further 5 days at nonpermissive temperature (39°C), was phagocytic, and had accumulated at peak 1.0. Cells in peak 1.0 moved to peak 1.6 and to higher positions, after the strictly resting culture was sparsely reseeded and incubated at 33°C. In contrast, the DNA content distribution of the successively proliferating cells, which were obtained by repeated passage of an extensively proliferating culture and none of which were phagocytic, was similar to that of proliferating hypotetraploid BALB/c3T3 fibroblasts with a G1 peak at 1.6 unit followed by a plateau containing S- and G2-phase cells. The peak 1.0 cell population appeared from the recloned population of the successively proliferating cells in company with the restoration of the culture condition-dependent phagocytic ability when cocultured with primary macrophages. Each peak in the flow cytogram reflected fairly well DNA content per cell as determined by other methods.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: By using a photoaffinity ligand, cell extracts from transformed macrophages that were established by infection with temperature-sensitive mutants (tsA640) of simian virus 40 (SV40) were examined for cyclic adenosine 3′:5′-monophosphate (cAMP)-binding proteins. At the nonpermissive temperature for SV40 large T antigen, 39.0°C, no significant cAMP-binding proteins could be detected, such as primary mouse macrophages. At the permissive temperature of 33.0°C, cAMP-binding proteins appeared later than SV40 T antigen expression and cellular DNA synthesis. The profile of cAMP-binding proteins was similar to that of resting, but not proliferating, mouse clonal fibroblasts (BALB/c 3T3). These and previous results suggest that SV40 T antigen influences the expression of cAMP-binding proteins in tsA640-transformed macrophages; the large/small T antigen converts the profile of cAMP-binding proteins from macrophage to fibroblastic cells.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mouse macrophages transformed by a temperature-sensitive mutant (tsA640) of simian virus 40 (SV40) were examined by immunofluorescence microscopy for fibronectin expression and actin distribution. Resting cultures of tsA640 transformants incubated at a temperature nonpermissive for SV40 large T antigen (39.0°C) exhibited phagocytic activity and did not exhibit cellular fibronectin and actin cables, like primary cultures of resident macrophages. When the resting cultures were sparsely seeded and shifted down to the permissive temperature of 33.0°C, expression of large T antigen in the nucleus, expression of fibronectin in the cytoplasm, and cellular entry into S phase occurred in that temporal order, followed by actin cable formation, cellular proliferation, and diminishment of phagocytic activity. The expression of T antigen and fibronectin was sensitive to actinomycin D and cycloheximide. The expression of fibronectin was insensitive to inhibitors of DNA synthesis, whereas the expression of actin cables was sensitive. These results suggest that SV40 T antigen leads macrophages to express fibronectin and actin cables, as well as resumption of cell proliferation, and that entry into S phase is not required for fibronectin expression but may be required for actin cable formation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The levels of simian virus 40 (SV40) large T antigen in a tsA-transformed mouse macrophage line at the permissive (33°C) and the nonpermissive (30°C) temperature were examined by immunofluorescence, sodium dodecylsulfate-polyacrylamide gel electrophoresis, complement fixation, and enzyme-linked immunosorbent assay. When the cells were confluent and rested at 33°C, and then were shifted to 39°C, the amount of large T antigen per cell decreased, and most cells survived and remained phagocytic. When the cells were proliferating at 33°C, and then were shifted to 39°C, the cells died with only a small reduction in the amount of large T antigen. Therefore, the physiological state of the cells may determine the survival of cells by affecting the level of large T antigen after exposure to 39°C. The confluent cells may be rested with a concomitant decrease of large T antigen. The proliferating cells may not survive in the presence of a relatively high level of functionally defective large T antigen at 39°C.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...