Inhibition of DNA restriction enzyme digestion by anthracyclines

The inhibition of restriction enzyme digestion of lambda phage DNA by anthracyclines (i.e., adriamycin, daunomycin, epirubicin, idarubicin and esorubicin) commonly used in the treatment of human leukemia and cancer has been studied in vitro. The anthracyclines used inhibit DNA digestion by SmaI, AvaII, HaeIII, HhaI and HpaII, which cut DNA at guanine-cytosine (G-C) sequence sites, and by EcoRI, which cut DNA at adenine adenine-thymine thymine (AATT) sequence sites. Adriamycin completely inhibits DNA restriction by the indicated enzymes, daunomycin, epirubicin and idarubicin determine only a partial inhibition, while esorubicin does not inhibit DNA restriction at all. An attempt is made to correlate the extent of the in vitro interaction between anthracyclines and DNA to in vivo cardiotoxicity.

Translocation of oncogene c-sis from chromosome 22 to chromosome 17 in a human myelogenous leukemia cell line

By combining somatic cell genetics, in situ hybridization and Southern hybridization, we found that the c-sis oncogene in the human myelogenous leukemia cell line ML3 is translocated from the long arm (q11----qter) of chromosome 22 to the long arm (mid-portion or q21 region) of chromosome 17. This translocation does not result in rearrangement of the c-sis oncogene.

Repeated nucleotide sequences in human main band DNA

Male and female human placenta DNA was fractionated in an Ag+-Cs2SO4 density gradient. The different fractions along the gradient were analyzed by Hae III endonuclease digestion. Within the main band DNA on the light side a component having a Hae III digestion pattern similar to that of human satellite III DNA has been identified. This component which might be defined as a cryptic satellite accounts for at least 3% of the total human DNA and has a different position than human satellite III in Ag+-Cs2SO4.

Satellite DNAs in eukaryotes: a non-adaptive mechanism of speciation which originated with sexual reproduction?

Satellite DNAs may have originated during evolution at the same time as sexual reproduction in order to suppress crossingover between the 2 heterogametic sex chromosomes, and may have acquired a function of sterility barriers in hybrid species during evolution. This origin of satellite DNAs appears to be reflected in different stages of speciation: partial and total heterogametic sex hybrid sterility and full hybrid sterility might correspond to subspecies, semispecies and full species.

Homology between Cellular Repeated Nucleotide Sequences and a Murine Leukemia Viral Genome

Moloney murine leukemia virus c-DNA hybridizes mainly with cellular middle repeated sequences of NIH-Swiss mouse spleen DNA, fragmented to different lengths, denatured and renatured to an intermediate value of Cot, and fractionated in an Ag+-Cs2SO4 preparative gradient suitable to separate unique, middle repeated and highly repeated DNA.

The organization of DNA sequences in the mouse genome

Analysis of the organization of nucleotide sequences in mouse genome is carried out on total DNA at different fragment size, reannealed to intermediate value of Cot, by Ag+--Cs2SO4 density gradient centrifugation.--According to nuclease S-1 resistance and kinetic renaturation curves mouse genome appears to be made up of non-repetitive DNA (76% of total DNA), middle repetitive DNA (average repetition frequency 2X10(4) copies, 15% of total DNA), highly repetitive DNA (8% of total DNA) and fold-back DNA (renatured density 1.701 g/ml, 1% of total DNA).--Non-repetitive sequences are intercalated with short middle repetitive sequences. One third of non-repetitive sequences is longer than 4500 nucleotides, another third is long between 1800 and 4500 nucleotides, and the remainder is shorter than 1800 nucleotides.--Middle repetitive sequences are transcribed in vivo. The majority of the transcribed repeated sequences appears to be not linked to the bulk of non-repeated sequences at a DNA size of 1800 nucleotides.--The organization of mouse genome analyzed by Ag+--Cs2SO4 density gradient of reannealed DNA appears to be substantially different than that previously observed in human genome using the same technique.

The organization of repeated DNA sequences in the human genome

The arrangement of repetitive and non-repetitive DNA sequences was studied in the human genome. By Ag+-Cs2SO4 density gradient centrifugations of human DNA at different fragment size reannealed to different Cot values and c-RNA hybridization experiments, we have shown the presence of two repetitive DNA fractions, called fast and slow intermediate DNA, with different pattern of sequence organization. The fast intermediate DNA sequences (6% of the genome; CsCl density in renatured form: 1.703 g/ml) are in part clustered in fragments greater than 24,000 nucleotide pairs and in part in fragments ranging from 1,800 to 600 nucleotide pairs spaced with longer more complex sequences. The slow intermediate DNA sequences (30% of the genome; CsCl density in renatured form: 1.707 g/ml) appear to be finely interspersed with non-repetitive sequences. At a DNA fragment size of 600 nucleotide pairs only a third of the slow intermediate DNA sequences are free of unique sequences, while the other two thirds are still organized with unique sequences. It has also been shown that a great amount of the repetitive DNA sequence transcripts in heterogeneous nuclear RNA of HeLa cells are complementary to slow intermediate DNA sequences.

Molecular basis of chromosome banding. I. The effect of mouse DNA fractions on two fluorescent dyes in vitro

The effects of mouse satellite, main band and total DNA on the fluorescence intensity of quinacrine and of the bibenzimidazole derivative Hoechst 33258 were tested in solution. No significant differences were noticed between the double-stranded DNAs in spite of the 5% difference in AT-content between satellite and main band DNA. Single-stranded DNAs enhanced the fluorescence intensity of Hoechst 33258 far less than double-stranded DNAs. Having been denaturated and then reassociated the DNA fractions were intermediate in their enhancing effects on the fluorescence intensity of Hoechst 33258, the differences presumably being due to different degrees of reassociation. The effect of denatured and subsequently reassociated satellite DNA on the fluorescence intensity of quinacrine was similar to that of the native DNAs. Main band and total DNA quenched the fluorescence intensity of quinacrine more after denaturation-reassociation than it did when native. In the discussion the results are related to known cytological data.

Human leukemic intermediate DNA components

The DNA extracted from human leukemic leucocytes has been fractionated on a methylated albumin kieselguhr (MAK) column. The different fractions obtained have been reannealed to a Cot value of 20 mol times sec/1 to study the distribution of the intermediate DNA on the MAK column. Intermediate DNA contains two components, one (CsCl density after reannealing, 1.703 g/ml) obtained by reannealing high molecular weight DNA, the other (CsCl density after reannealing, 1.707 g/ml) obtained only by reannealing sonicated low molecular weight DNA. High molecular weight intermediate DNA (1.703 component) is eluted early from the MAK column in the fractions corresponding to the main DNA peak, while low molecular weight intermediate DNA (1.707 component) is more widespread on the MAK column, but appears to be enriched in the fractions eluted later. The possibility is discussed that the latter component is interspersed in that part of the genome which is apparently more homogeneous in density in an analytical CsCl gradient, and is absent on the skewed, more heterogeneous, heavy side of the main DNA in CsCl.

Hybridization of mouse leukemia virus c-DNA to mouse repeated DNA sequences

Experiments of hybridization between mouse leukemia virus synthetic 3H-DNA probe and mouse main band and satellite DNAs indicate that there is not a higher concentration of viral sequences in the satellite DNA. On the contrary, viral sequences appear to be enriched in the fast renaturing intermediate main band DNA.

Mitochondrial DNA in yeast and some mammalian species

Yeast DNA, in a cesium chloride density gradient, shows a minor or satellite band with a density lower than that of the main nuclear component. The DNA isolated from purified mitochondria of yeasts corresponds in density to this satellite band. In solution, this DNA more easily undergoes renaturation as compared to DNA from cell nuclei. The ease of this renaturation is presumably due to a homogeneity greater than that of nuclear DNA. Mitochondrial DNA isolated from several mammalian species has the same or higher density than nuclear DNA, but differs in its ready renaturability.