Cell biology international reports最新文献

Nucleation of microtubule (MT) organization of the cytoplasmic microtubule complex (CMTC) from the microtubule organizing centres (MTOC) was studied in enucleated cytoplasts of human diploid fibroblast (MRC-5) and mouse peritoneal macrophages in culture. Cytoplasts of both cell types could not organize the complete CMTC. Aberrant MT patterns were seen in MRC-5 cells while mouse macrophages showed occurrence of few short MT. The studies suggest that nucleus may have a role in determining CMTC.

The organization of the chondriome and the ultrastructure of mitochondria have been studied in eggs and embryos of the sea urchin Paracentrotus lividus.

The egg chondriome is characterized by an arrangement in well-delimited clusters. Analysis of mitochondrial clusters on electron micrographs of ultrathin serial sections shows two kinds of mitochondria of different shapes, the rod-shaped and the spherical. The egg mitochondria have a dense matrix and a well-ordered arrangement of cristae which, in rod-schaped variety, are perpendicular to the major axis.

Cell division is accompanied by significant changes in intracellular distribution of mitochondria and in their structure. At the stage of 2–4 blastomeres, the clusters break up and numerous mitochondrial rods show signs of fragmentation; most of the observable mitochondria are of spherical shape. At the same time, the matrix becomes less dense, and the orderly arrangement of the cristae disappears.

From the blastula to the gastrula stage, the observed modifications are reversed: the number of spherical-shaped mitochondria decreases, while that of the rod-shaped increases; the diameter of the latter is almost equal to the initial diameter of the spherical forms, the matrix becomes dense again and the cristae resume their orderly arrangement.

To determine if deleterious effects of heat shock on embryos could be reduced in vitro by glutathione or taurine, morulae from superovulated cows were placed in modified Hams-F10 medium supplemented with 50 nM glutathione (GSH), 50 mM taurine or neither. Morulae were incubated for 2 hours at 38.5°C, then at 42.0°C (heat shock) or 38.5°C for 2 hours and followed by incubation at 38.5°C for 20 hours. Neither GSH nor taurine enhanced viability or blastocyst development at 38.5°C. At 42.0°C, however, GSH and taurine increased (P < 0.02) viability (73 %, 41 % and 26 % live for GSH, taurine and control); GSH increased (P < 0.05) blastocyst development (55 % for GSH vs. 30 % for control). In conclusion, partial thermoprotection of bovine embryos from heat shock can be achieved in vitro by administration of GSH. Taurine is only slightly effective.

The effects of human hepatocyte growth factor (hHGF), a potent mitogen for rat and human hepatocytes in primary culture, on proliferation of human hepatoma and hepatoblastoma cells were examined. Out of five cell lines; HLE, HuH-6 Clone 5, HuH-7, PLC/PRF/5, and Hep G2, only HuH-6 Clone 5 cells were stimulated by recombinant hHGF. Both native and recombinant hHGFs caused dose-dependent increases in cell number and DNA synthesis of cells. This stimulation was strongly inhibited by anti-hHGF monoclonal antibody.

Morphological observations on the V-79-379 A cells after treatment with equinatoxin II (EqT II), isolated from the sea anemone Actina equina L., and fetal calf serum (FCS) treated toxin were examined by transmission electron microscopy. Our results showed that the cells incubated with FCS treated EqT II were almost ultrastructurally unaltered. When the cells were treated with low concentrations of EqT II alone cell ultrastructure was altered with the evidence of numerous blebs and decreased microvilli number on the cell surface and appearance of numerous vesicles in the Golgi regions. High concentrations of EqT II caused disintegration of plasmalemma and intracellular membranes as well as degradation of cytosol.

A cell culture system for the study of human serum growth factors is described. It is based on a diploid human embryonic lung fibroblast cell strain (Flow 2002) with a finite life span (60±3 CPDS). When maintained in homologous (human) plasma-derived serum (PDS) at concentrations as low as 0.05%, the cells attain quiescence. Under these conditions, they remain viable for at least 14 days and they readily respond when stimulated to proliferate by human serum or human PDS, as well as by growth factors, such as PDGF, EGF, FGF. During in vitro aging, the cells retain their responsiveness to these growth stimuli, although the net proliferative effect decreases as they approach senescence.