Mapping and characterization of a novel human myc-like (MYCLK1) sequence.

The myc family of proto-oncogenes consists of several members that possess regions of sequence homology and some have known similarities in structure and function. We have isolated an 8.8-kb EcoRI fragment from a human genomic library by hybridization to a 28-base oligonucleotide probe derived from a region of the second exon of MYC, which is highly conserved in the myc gene family. Sequence analysis of this myc-like (MYCLK1) DNA fragment has revealed the existence of a region with 85% homology to the 28-base oligonucleotide probe. An open reading frame of 207 nucleotides containing the region of homology was found. We have mapped MYCLK1 to human chromosome 7 at band p15 by chromosome in situ hybridization; this site is distinct from the map location of previously characterized myc genes. Whether MYCLK1 represents a new functional member of the myc family of proto-oncogenes remains to be determined.     

Development and characterization of a human cell line from an ovarian mixed mullerian tumor (carcinosarcoma)

Summary A cell line derived from a human ovarian carcinosarcoma was established in tissue culture and in nude mice. Two sublines, LDF and HDF, separated by discontinuous density centrifugation were also established from the parent line JoN. The cloning efficiency of the JoN line was 21%. Morphologic features of adenocarcinoma cells characteristic of the parent JoN cells were retained in the sublines and clones; all lines showed the same karyotype and DNA content (pseudodiploid and pseudotetraploid). Keratin, as demonstrated immunohistochemically, was strongly expressed in the parent line JoN and the xenograft tumor, but not at all in the LDF sublines and only moderately in the HDF sublines. Vimentin, however, was expressed in neither the parent line JoN nor the xenograft tumor, but was present in both sublines. Transglutaminase and plasminogen activator activity was high in the parent line JoN. Neither, sublines nor clones showed the same high enzyme activity as the parent line. It is concluded that this human tumor line JoN is comprised of epithelial cells, capable of multidirectional differentiation.     

Changes in superoxide dismutase activity in the presence of electron donors and acceptors

The activity of superoxide dismutase (SOD) from bovine erythrocytes was measured by the inhibition of nitrotetrazolium blue reduction rate in superoxide anion radical generation systems--xanthine/xanthine oxidase of NADH/phenazine methasulfate. The enzyme activity increases in the presence of compounds acting as electron donors in radical-involving reactions and decreased in the presence of compounds possessing the properties of electron acceptors. Activation of SOD by electron donors and its inhibition by electron acceptors was dependent on the concentration of the above compounds. In the absence of SOD electron donors and acceptors did not change the rate of tetrazolium blue reduction by superoxide anion radicals. The role of the new type of SOD regulation for the enzyme functioning in the cell is discussed.     

A comparison of liquid-holding recovery and photoreactivation in halophilic and non-halophilic bacteria

The ability of the extreme halophile Halobacterium cutirubrum to recover from the effects of ultraviolet radiation during liquid holding in the dark in non-nutrient medium has been compared with that of (i) a moderately halophilic bacterium (NRC 41227) and (ii) Escherichia coli B. The photoreactivabilities of all three bacteria have also been studied. The extreme halophile was incapable of liquid-holding recovery in these conditions, in marked contrast to both E. coli B and the moderate halophile, and also failed to recover when held in nutrient medium in the dark. These results strongly support the hypothesis that H. cutirubrum lacks DNA excision repair. It was also found that ultraviolet-irradiated H. cutirubrum could be almost completely photoreactivated from any level of survival in the range 10(-4)-80%, provided exposure to visible light was not delayed, whereas the moderate halophile resembled E. coli B and had a comparatively limited capacity for photoreactivation.     

Comparative analysis of the HBsAg level in human blood preparations

A total of 218 batches of blood preparations produced from different raw materials have been studied by means of enzyme immunoassay kits (Abbott Laboratories, USA). The assays have revealed that the preparations under study are nonstandard with respect to the content and isolation rate of HBsAg, the marker of hepatitis B virus. These data necessitate search for the ways of improving the quality of blood preparations.     

Establishment of human tumor strains from cell lines transplanted into athymic mice and rats

The authors describe human cancer strains established from 6 cell lines transplanted to nude mice and rats: cancer of the liver, colon, lung, bladder and Burkitt's lymphoma. In spite of a long history (for several years) of cell line transfers in vitro, on transplantation of tumor cells, nude animals established tumors histologically identical to the primary cancer.