DNA fingerprint analysis for the detection of induced mutations in mammalian cells in culture

A mutation assay in cultured mammalian cells based on the direct analysis of minisatellite DNA was developed. Band pattern variations reflect DNA alterations ranging from single base changes to complex rearrangements. By DNA fingerprinting a large number of autosomal loci throughout the human genome can be simultaneously checked, therefore minimizing the size of the samples of cell colonies to be scored in the absence of phenotypic selection. For the mutation assay chinese hamster cells (V79) were treated with Nitrosoguanidine and 14 independent colonies were isolated and expanded. DNA fingerprints were obtained after digestion of the DNA extracted from each clone with bothHinfI andHae III, and hybridisation with both 33.15 and 33.6 probes. Twelve colonies from untreated cells were also analysed. Several differences in the band pattern of treated colonies were observed when compared with untreated cells; digestion withHae III and hybridisation with 33.15 probe allowed the detection of the highest frequency of induced variants. The results suggest that minisatellite sequences are hypermutable sites that can be used to monitor the mutagenic potential of chemical agents directly at the DNA level, without phenotypic selection. Moreover, with the method herein decribed, it is possible to distinguish between true mutations and epimutations, such as those caused by changes in DNA methylation.     

The synthesis of cartilage collagen by rabbit and human chondrocytes in primary cell culture

Summary This report describes a method for preparing primary cell cultures of differentiated rabbit sternal and human vertebral cartilage cells. These cell cultures were shown to synthesize primarily α1 chains, which is taken to mean that at least 82% of the collagen produced is cartilage specific collagen (type II). This work was supported in part by grant HD-05505 from NIH.     

The number and distribution pattern of Golgi bodies in cells of Micrasterias (Conjugates, Chlorophyta) examined by fluorescence microscopy and electron microscopy

The number and the distribution pattern of Golgi bodies in cells of Micrasterias americana and Micrasterias crux-melitensis were examined both by fluorescence microscopy and by electron microscopy. Golgi bodies intensely absorbed the fluorescent dye DiOC6(3) and strongly radiated fluorescent light. The number of Golgi bodies nearly doubled before septum formation, and half of the Golgi bodies entered each sister cell. Many Golgi bodies migrated from the non-growing half-cell to the growing half-cell where new cell walls were actively being synthesized. Most Golgi bodies were not in contact with chloroplasts in the growing half-cell. Half of the Golgi bodies moved back to the non-growing half-cell 6–12 h after completion of the new half-cell. Golgi bodies were in contact with the surfaces of chloroplasts 12 h after full growth.