Nuclear DNA

About: Nuclear DNA is a research topic. Over the lifetime, 3933 publications have been published within this topic receiving 185830 citations.

Synthesis of herpes simplex virus, vaccinia virus, and adenovirus DNA in isolated HeLa cell nuclei. I. Effect of viral-specific antisera and phosphonoacetic acid.

Abstract: Purified nuclei, isolated from appropriately infected HeLa cells, are shown to synthesize large amounts of either herpes simplex virus (HSV) or vaccinia virus DNA in vitro The rate of synthesis of DNA by nuclei from infected cells is up to 30 times higher than the synthesis of host DNA in vitro by nuclei isolated from uninfected HeLa cells Thus HSV nuclei obtained from HSV-infected cells make DNA in vitro at a rate comparable to that seen in the intact, infected cell Molecular hybridization studies showed that 80% of the DNA sequences synthesized in vitro by nuclei from herpesvirus-infected cells are herpesvirus specific Vaccinia virus nuclei from vaccinia virus-infected cells, also produce comparable percentages of vaccinia virus-specific DNA sequences Adenovirus nuclei from adenovirus 2-infected HeLa cells, which also synthesize viral DNA in vitro, have been included in this study Synthesis of DNA by HSV or vaccinia virus nuclei is markedly inhibited by the corresponding viral-specific antisera These antisera inhibit in a similar fashion the purified herpesvirus-induced or vaccinia virus-induced DNA polymerase isolated from infected cells Phosphonoacetic acid, reported to be a specific inhibitor of herpesvirus formation and the herpesvirus-induced DNA polymerase, is equally effective as an inhibitor of HSV DNA synthesis in isolated nuclei in vitro However, we also find phosphonoacetic acid to be an effective inhibitor of vaccinia virus nuclear DNA synthesis and the purified vaccinia virus-induced DNA polymerase In addition, this compound shows significant inhibition of DNA synthesis in isolated nuclei obtained from adenovirus-infected or uninfected cells and is a potent inhibitor of HeLa cell DNA polymerase alpha

Genomic rearrangements correlated with antigenic variation in Trypanosoma brucei.

Abstract: The capacity of African trypanosomes to express sequentially a large repertoire of different surface antigens during an infection enables the parasite to evade the immune response of its host, and makes attempts to produce a vaccine against the disease difficult. It is evident that point mutations cannot account for antigen diversity. Variable antigens like immunoglobulins are derived from an extensive family of genes of which only one is expressed in a given cell. As somatic tic recombination is involved in the immunoglobulin gene system, this similarity prompted us to search for somatic rearrangements in trypanosome variable antigen genes. We have constructed a recombinant plasmid containing approximately half the DNA sequence coding for a Trypanosoma brucei variable antigen and hybridised the inserted sequences to various restriction enzyme digests of nuclear DNA from different trypanosome clones. Differences in the sizes of restriction tion fragments hybridising to the inserted variable antigen coding sequence show altered positions of enzyme sites relative to this sequence, indicating different arrangements of DNA sequences around this gene in different trypanosome clones.

DNA content in the genus Xenopus.

Abstract: Nuclear DNA amounts were determined by cytofluorometry for twelve species and subspecies of the genus Xenopus. Absolute values, in pg per nucleus, were obtained by direct comparison with human lymphocyte nuclei. The lowest DNA amount (3.55 pg) was found in X. tropicalis, which possess only 20 chromosomes, and the highest (16.25 pg), in the hexaploid X. ruwenzoriensis, with 108 chromosomes. The two recently discovered tetraploid species, X. sp.n. and X. vestitus have, respectively, 12.57 and 12.83 pg of DNA. Among the species and subspecies with 36 chromosomes, the DNA content ranges from 6.35 to 8.45 pg.

Identification of new eukaryotic tRNA genes in genomic DNA databases by a multistep weight matrix analysis of transcriptional control regions.

Abstract: A linear method for the search of eukaryotic nuclear tRNA genes in DNA databases is described. Based on a modified version of the general weight matrix procedure, our algorithm relies on the recognition of two intragenic control regions known as A and B boxes, a transcription termination signal, and on the evaluation of the spacing between these elements. The scanning of the eukaryotic nuclear DNA database using this search algorithm correctly identified 933 of the 940 known tRNA genes (0.74% of false negatives). Thirty new potential tRNA genes were identified, and the transcriptional activity of two of them was directly verified by in vitro transcription. The total false positive rate of the algorithm was 0.014%. Structurally unusual tRNA genes, like those coding for selenocysteine tRNAs, could also be recognized using a set of rules concerning their specific properties, and one human gene coding for such tRNA was identified. Some of the newly identified tRNA genes were found in rather uncommon genomic positions: 2 in centromeric regions and 3 within introns. Furthermore, the presence of extragenically located B boxes in tRNA genes from various organisms could be detected through a specific subroutine of the standard search program.