Effect of 2 MHz ultrasound on DNA, RNA and protein synthesis in Pisum sativum root meristem cells.

The amounts of DNA, RNA and protein synthesis were determined in Pisum sativum root meristem cells at various times after a 1 min exposure to 1 MHz ultrasound at a power density of 30 W/cm2. Immediate depressions in all three macromolecular syntheses occurred after sonication, followed by an apparent recovery several hours later. These events appear to correlate in time with the subsequent reduction and recovery in mitotic index in Pisum sativum root meristem cells exposed to 2 MHz ultrasound.     

Studies on DNA content, RNA synthesis, and DNA template activity in aging cells of Paramecium aurelia.

Investigations by Feulgen microspectrophotometry in Paramecium aurelia indicated that as fission age increased the amount of macronuclear DNA decreased. It was also found that the amount of RNA synthesis as determined by the in vivo incorporation of [³H]uridine decreased as the fission age increased. An alternative in situ assay of the DNA template activity determined by the RNA polymerase-catalyzed incorporation of [³H]UTP is described. The DNA template activity of older cells was shown to be significantly lower on a per cell basis than that of younger cells. The majority of this reduction was shown to be due to the gradual loss of DNA template with an increase in fission age. The specific activity of the DNA template, however, does show a small but significant decrease as the fission age of the cell increases.     

Difference in the action of ethyl and methyl methane sulfonates on DNA template activity for RNA synthesis in vitro.

RNA produced in vitro from alkylated T7 DNA has been characterized by polyacrylamide gel electrophoresis. Methylation of T7 DNA by methyl methane sulfonate reduces RNA chain length. In contrast, ethylation of T7 DNA by ethyl methane sulfonate, while reducing RNA synthesis to the same extent, does not alter chain length.     

Primer RNA for DNA synthesis on single-stranded DNA template in a cell free system from Drosophila melanogaster embryos

A cytoplasmic extract of Drosophila melanogaster early embryos supported DNA synthesis which was dependent on an added single stranded DNA template, phi X174 viral DNA. The product DNA made during early reaction was about 100 to 600 nucleotides in length and complementary to the added template. After alkali treatment, 70 to 80 per cent of the product DNA chains exposed 5'-hydroxyl ends, suggesting covalent linkage of primer RNA at their 5'-ends. Post-labeling of 5'-ends of the product DNA with polynucleotide kinase and [gamma-32P]ATP revealed that oligoribonucleotides, mainly hexa- and heptanucleotides, were covalently linked to the 5'-ends of the majority of the DNA chains. The nucleotide sequence of the linked RNA was mainly 5'(p)ppApA(prN)4-5, where tri- (or di-) phosphate terminus was detected by the acceptor activity for the cap structure with guanylyltransferase and [alpha-32P]GTP. The structure of this primer RNA was comparable to that of the octaribonucleotide primer isolated from the nuclei of Drosophila early embryos.     

Effects of ultrasound on DNA and RNA synthesis in preimplantation mouse embryos.

Ultrasound is used extensively to monitor the growth of ovarian follicles in in vitro fertilization and embryo transfer (IVF-ET) programs, as well as to follow the progress of early pregnancy. There have been scattered reports in the literature that exposure to ultrasound may have an adverse effect on reproduction in the rat (Bologne et al: CR Soc Biol 177:381-387, 1983; Demoulin et al: Ann NY Acad Sci 442:146-152, 1985), and also in humans (Demoulin et al: Ann NY Acad Sci 442: 146-152, 1985). We report here that diagnostic levels of pulsed ultrasound did not affect either the number of embryos produced, or the ability to incorporate labelled precursors into DNA and RNA, respectively. Measurements of temperature elevation of ovaries exposed to ultrasound showed that neither controls nor experimental tissue exhibited temperature elevation greater than 1 degree C.     

Effect of denaturation of DNA template on activity of RNA polymerase of class B

The effect of the denaturation of homologous and calf thymus DNA on the RNA polymerase B activity purified from rat liver and spleen and Ehrlich ascites cells, was investigated in presence of either Mn2+ or Mg2+ and in presence or absence of alpha-amanitin. On the basis of the results here reported, we suggest: 1) denatured DNA is more effective than native as template for polymerase B; 2) denatured DNA template and cations might play a role in determining the extent of the reaction alpha-amanitin-polymerase B.     

Effect of distamycin a on the structure and template activity of DNA in RNA - polymerase system

It is shown that native and denatured DNA form complexes with the oligopeptide-antibiotic distamycin A. The pronounced inhibition of the incorporation of AMP into RNA in the DNA directed RNA-polymerase system is due to the interference of the antibiotic with DNA.