Nuclear DNA

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

Mitochondrial DNA Mutations Regulate Metastasis of Human Breast Cancer Cells

Abstract: Mutations in mitochondrial DNA (mtDNA) might contribute to expression of the tumor phenotypes, such as metastatic potential, as well as to aging phenotypes and to clinical phenotypes of mitochondrial diseases by induction of mitochondrial respiration defects and the resultant overproduction of reactive oxygen species (ROS). To test whether mtDNA mutations mediate metastatic pathways in highly metastatic human tumor cells, we used human breast carcinoma MDA-MB-231 cells, which simultaneously expressed a highly metastatic potential, mitochondrial respiration defects, and ROS overproduction. Since mitochondrial respiratory function is controlled by both mtDNA and nuclear DNA, it is possible that nuclear DNA mutations contribute to the mitochondrial respiration defects and the highly metastatic potential found in MDA-MB-231 cells. To examine this possibility, we carried out mtDNA replacement of MDA-MB-231 cells by normal human mtDNA. For the complete mtDNA replacement, first we isolated mtDNA-less (ρ0) MDA-MB-231 cells, and then introduced normal human mtDNA into the ρ0 MDA-MB-231 cells, and isolated trans-mitochondrial cells (cybrids) carrying nuclear DNA from MDA-MB-231 cells and mtDNA from a normal subject. The normal mtDNA transfer simultaneously induced restoration of mitochondrial respiratory function and suppression of the highly metastatic potential expressed in MDA-MB-231 cells, but did not suppress ROS overproduction. These observations suggest that mitochondrial respiration defects observed in MDA-MB-231 cells are caused by mutations in mtDNA but not in nuclear DNA, and are responsible for expression of the high metastatic potential without using ROS-mediated pathways. Thus, human tumor cells possess an mtDNA-mediated metastatic pathway that is required for expression of the highly metastatic potential in the absence of ROS production.

Restriction fragment length polymorphism

Abstract: In the 1960s, a group of enzymes were discovered in bacteria that could degrade incoming bacteriophage DNA and would ‘restrict’ their establishment in the cell [2,6]. These enzymes, known as restriction enzymes [19], have proved very valuable in modern manipulations of DNA. The first enzymes described (type I) require various cofactors and lack sequence specificity for their sites of cleavage. However, a second class (type II) were discovered that require only Mg2+ asa cofactor and have the distinct advantage that they recognize and cleave very specific sequences. Type II restriction enzymes are therefore capable of reducing complex DNA, such as plant nuclear DNA, into a population of fragments with discrete sizes. At least 475 restriction endonucleases have been described to date [24].

Distinguishing fall armyworm (lepidoptera : noctuidae) strains using a diagnostic mitochondrial dna marker

Abstract: The fall armyworm, Spodoptera frugiperda (J. E. Smith), includes morphologically indistinguishable corn and rice strains. The two strains were surveyed for diagnostic restriction patterns in mitochondrial DNA (mtDNA) using 25 restriction endonucleases. Polymorphic mtDNA restriction patterns were identified for BstNI, HinfI and MspI. The MspI pattern was the most distinctive since the molecular size of each DNA fragment differed between the two strains. Analyses of laboratory and field-collected insects showed the MspI mtDNA pattern to be a diagnostic marker for corn and rice strain insects. Strain identification by the MspI mtDNA profile correlated exactly with nuclear DNA markers. Since no HaeIII sites are present in fall armyworm mtDNA, a double-digest of total fall armyworm DNA using HaeIII and MspI allowed the direct detection of mtDNA restriction fragments from total DNA on a stained agarose gel. In contrast to conventional techniques utilizing mtDNA markers, this rapid and simple procedure does not require the isolation of mtDNA, or avoids the use of DNA blots and labeled mtDNA.

Endonuclease G is required for early embryogenesis and normal apoptosis in mice

Abstract: Endonuclease G (EndoG) is a nuclear-encoded mitochondrial protein reported to be important for both nuclear DNA fragmentation during apoptosis and mitochondrial DNA replication. To evaluate the in vivo function of EndoG, we have investigated the effects of EndoG deficiency in cells and mice. We found that EndoG homozygous mutant embryos die between embryonic days 2.5 and 3.5. Mitochondrial DNA copy numbers in ovulated oocytes from EndoG heterozygous mutant and wild-type mice are similar, suggesting that EndoG is involved in a cellular function unrelated to mitochondrial DNA replication. Interestingly, we found that cells from EndoG heterozygous mutant mice exhibit increased resistance to both tumor necrosis factor α- and staurosporine-induced cell death. Moreover, spontaneous cell death of spermatogonia in EndoG heterozygous mutant mice is significantly reduced compared with wild-type mice. DNA fragmentation is also reduced in EndoG+/- thymocytes and splenocytes compared with wild-type cells, as well as in EndoG+/- thymus in vivo compared with that of the wild-type mice, on activation of apoptosis. These findings indicate that EndoG is essential during early embryogenesis and plays a critical role in normal apoptosis and nuclear DNA fragmentation.

Evolution of the genus Leishmania as revealed by comparisons of nuclear DNA restriction fragment patterns

Abstract: Restriction endonuclease DNA fragment patterns have been used to examine the relationships among 28 isolates of Leishmania as well as Crithidia, Endotrypanum, and Trypanosoma cruzi. Fragments of nuclear DNA were generated with six restriction enzymes, and blots were hybridized with probes from three loci. Among the major lineages the fragment patterns are essentially completely different, while within the major lineages various degrees of divergence are found. Molecular evolutionary trees were constructed using the method of Nei and Li to estimate the percent nucleotide sequence divergence among strains from the fraction of fragments shared. Defined groups, such as species or subspecies within the major lineages, are also grouped by nuclear DNA comparisons. Within the donovani complex, we find Leishmania donovani chagasi and Leishmania donovani infantum to be as similar as strains within Leishmania donovani donovani, consistent with the proposal by other workers that New World visceral leishmaniasis originated quite recently.