Mammary epithelial cells from rats and humans show both quantitative and qualitative species- and carcinogen-specific differences in their abilities to activate benzo(a)pyrene (B(a)P) and 7,12-dimethylbenz(a)anthracene (DMBA). Previous studies of the DNA binding of these compounds in mammary epithelial cells demonstrated that rat cells bound relatively more DMBA than B(a)P to DNA under identica...

Neuronal and astroglial cells were prepared from whole brain of three month and 30-month- old rats for study of alterations in the nuclear poly ADP-ribosylation and DNA breaks with age. The relative purity of the cell preparations was confirmed by the determination of the neurofilament (low molecular weight) and glutamine synthetase content of the cells using ELISA. An increase (75%) in th...

c-raf is a serine-threonine kinase and a downstream effector of ras signaling. This kinase plays an essential role in cell proliferation, differentiation, and apoptosis. In the past, we reported induction of c-raf gene expression in rat liver cancer on treatment with a mixture of aryl hydrocarbon receptor (AhR) agonists. This prompted our interest in investigating the role of AhR in the transcr...

The light strand promoter of mammalian mitochondrial DNA gives rise to a primary transcript, but also to the RNA primer necessary for initiation of replication and 7S DNA synthesis as well as 7S RNA. Here we have studied the turnover of 7S DNA in isolated rat liver mitochondria and whether import of mitochondrial transcription factor A (mtTFA), which is necessary for transcription initiation, i...

Changes in mitochondrial DNA copy number and increases in mitochondrial DNA mutations, especially deletions, have been associated with exposure to mutagens and with aging. Common deletions that are the result of recombination between direct repeats in human and rat (4,977 and 4,834, bp, respectively) are known to increase in tissues of aged individuals. Previous studies have used long-distance ...

It has previously been reported that there may be a correlation between DNA synthesis and the growth of a series of rat hepatomas. This study describes a similar correlation that exists with DNA polymerase activity partially purified from normal liver and from 12 types of hepatomas. Not only are the hepatomas characterized by increased DNA polymerase levels, but the hepatoma enzymes prefer dena...

The Long-Evans Cinnamon (LEC) rat, an animal model for Wilson's disease, is an inbred mutant strain, which because of the genetic copper metabolism disorder develops hepatitis approximately 4 months after birth, followed by chronic hepatitis later in life, and eventually all of the surviving animals from liver injury and hepatitis develop spontaneous hepatocellular carcinomas. This animal model...

The rat growth hormone (rGH) gene contains two classes of repetitive DNA arranged as clusters within intron B and the 3' flanking region. The major family is equivalent to the CHO type 2 DNA. The second ("truncated repeat", TR) is a truncated version of the first and occurs in certain neural-specific transcripts and genes ("identifier" elements, ID). Here we report, using the HeLa cell-free tra...