scholarly journals Assignment of two mitochondrially synthesized polypeptides to human mitochondrial DNA and their use in the study of intracellular mitochondrial interaction.

1982 ◽  
Vol 2 (1) ◽  
pp. 30-41 ◽  
Author(s):  
N A Oliver ◽  
D C Wallace

Two mitochondrially synthesized marker polypeptides, MV-1 and MV-2, were found in human HeLa and HT1080 cells. These were assigned to the mitochondrial DNA in HeLa-HT1080 cybrids and hybrids by demonstrating their linkage to cytoplasmic genetic markers. These markers include mitochondrial DNA restriction site polymorphisms and resistance to chloramphenicol, an inhibitor of mitochondrial protein synthesis. In the absence of chloramphenicol, the expression of MV-1 and MV-2 in cybrids and hybrids was found to be directly proportional to the ratio of the parental mitochondrial DNAs. In the presence of chloramphenicol, the marker polypeptide linked to the chloramphenicol-sensitive mitochondrial DNA continued to be expressed. This demonstrated that resistant and sensitive mitochondrial DNAs can cooperate within a cell for gene expression and that the CAP-resistant allele was dominant or codominant to sensitive. Such cooperation suggests that mitochondrial DNAs can be exchanged between mitochondria.

1982 ◽  
Vol 2 (1) ◽  
pp. 30-41
Author(s):  
N A Oliver ◽  
D C Wallace

Two mitochondrially synthesized marker polypeptides, MV-1 and MV-2, were found in human HeLa and HT1080 cells. These were assigned to the mitochondrial DNA in HeLa-HT1080 cybrids and hybrids by demonstrating their linkage to cytoplasmic genetic markers. These markers include mitochondrial DNA restriction site polymorphisms and resistance to chloramphenicol, an inhibitor of mitochondrial protein synthesis. In the absence of chloramphenicol, the expression of MV-1 and MV-2 in cybrids and hybrids was found to be directly proportional to the ratio of the parental mitochondrial DNAs. In the presence of chloramphenicol, the marker polypeptide linked to the chloramphenicol-sensitive mitochondrial DNA continued to be expressed. This demonstrated that resistant and sensitive mitochondrial DNAs can cooperate within a cell for gene expression and that the CAP-resistant allele was dominant or codominant to sensitive. Such cooperation suggests that mitochondrial DNAs can be exchanged between mitochondria.


2008 ◽  
Vol 181 (7) ◽  
pp. 1117-1128 ◽  
Author(s):  
Robert W. Gilkerson ◽  
Eric A. Schon ◽  
Evelyn Hernandez ◽  
Mercy M. Davidson

Mitochondrial DNA (mtDNA) is packaged into DNA-protein assemblies called nucleoids, but the mode of mtDNA propagation via the nucleoid remains controversial. Two mechanisms have been proposed: nucleoids may consistently maintain their mtDNA content faithfully, or nucleoids may exchange mtDNAs dynamically. To test these models directly, two cell lines were fused, each homoplasmic for a partially deleted mtDNA in which the deletions were nonoverlapping and each deficient in mitochondrial protein synthesis, thus allowing the first unequivocal visualization of two mtDNAs at the nucleoid level. The two mtDNAs transcomplemented to restore mitochondrial protein synthesis but were consistently maintained in discrete nucleoids that did not intermix stably. These results indicate that mitochondrial nucleoids tightly regulate their genetic content rather than freely exchanging mtDNAs. This genetic autonomy provides a molecular mechanism to explain patterns of mitochondrial genetic inheritance, in addition to facilitating therapeutic methods to eliminate deleterious mtDNA mutations.


Genetics ◽  
1985 ◽  
Vol 109 (1) ◽  
pp. 195-213
Author(s):  
Jeffrey D Palmer ◽  
Richard A Jorgensen ◽  
William F Thompson

ABSTRACT Variation in 30 chloroplast DNAs, representing 22 wild and cultivated accessions in the genus Pisum, was analyzed by comparing fragment patterns produced by 16 restriction endonucleases. Three types of mutations were detected. First, an inversion of between 2.2 kilobase pairs (kb) and 5.2 kb distinguished a population of P. humile from all other Pisum accessions examined. Second, deletions and insertions of between 50 and 1200 base pairs produced small restriction fragment length variations in four regions of the 120-kb chloroplast genome. Two of these regions—one of which is located within the sequence that is inverted in P. humile—showed a high degree of size polymorphism, to the extent that size differences were detected between individuals from the same accession. Finally, a total of only 11 restriction site mutations were detected among the 165 restriction sites sampled in the 30 DNAs. Based on these results and previous data, we conclude that the chloroplast genome is evolving very slowly relative to nuclear and mitochondrial DNAs. The Pisum chloroplast DNA restriction site mutations define two major lineages: One includes all tested accessions of P. fulvum, which is known to be cytogenetically quite distinct from all other Pisum taxa. The second includes 12 of 13 cultivated lines of the garden pea (P. sativum) and a wild population of P. humile from northern Israel. These observations strongly reinforce an earlier conclusion that the cultivated pea was domesticated primarily from northern populations of P. humile. A 13th P. sativum cultivar has a chloroplast genome that is significantly different from those of the aforementioned lines and somewhat more similar to those of P. elatius and southern populations of P. humile. This observation indicates that secondary hybridization may have occurred during the domestication of the garden pea.


1991 ◽  
Vol 11 (4) ◽  
pp. 2236-2244 ◽  
Author(s):  
A Chomyn ◽  
G Meola ◽  
N Bresolin ◽  
S T Lai ◽  
G Scarlato ◽  
...  

A severe mitochondrial protein synthesis defect in myoblasts from a patient with mitochondrial myopathy was transferred with myoblast mitochondria into two genetically unrelated mitochondrial DNA (mtDNA)-less human cell lines, pointing to an mtDNA alteration as being responsible and sufficient for causing the disease. The transfer of the defect correlated with marked deficiencies in respiration and cytochrome c oxidase activity of the transformants and the presence in their mitochondria of mtDNA carrying a tRNA(Lys) mutation. Furthermore, apparently complete segregation of the defective genotype and phenotype was observed in the transformants derived from the heterogeneous proband myoblast population, suggesting that the mtDNA heteroplasmy in this population was to a large extent intercellular. The present work thus establishes a direct link between mtDNA alteration and a biochemical defect.


2007 ◽  
Vol 27 (1-3) ◽  
pp. 5-9 ◽  
Author(s):  
Salvatore DiMauro

The small, maternally inherited mitochondrial DNA (mtDNA) has turned out to be a hotbed of pathogenic mutations: 15 years into the era of ‘mitochondrial medicine’, over 150 pathogenic point mutations and countless rearrangements have been associated with a variety of multisystemic or tissue-specific human diseases. MtDNA-related disorders can be divided into two major groups: those due to mutations in genes affecting mitochondrial protein synthesis in toto and those due to mutations in specific protein-coding genes. Here we review the mitochondrial genetics and the clinical features of the mtDNA-related diseases.


Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 173-178 ◽  
Author(s):  
William E. A. Hintz ◽  
James B. Anderson ◽  
Paul A. Horgen

The ribosomal DNA (rDNA) repeat of Agaricus brunnescens (= A. bisporus) was cloned and mapped for six restriction endonucleases. The map positions of the 26S, 18S, and 5.8S rRNA genes on the 9.2 kilo base pairs (kbp) repeat were determined by alignment of sites conserved in the rRNA genes of other fungi. The rDNA restriction site maps for six isolates of A. brunnescens, five isolates of A. bitorquis, and three isolates of A. campestris were compared using cloned A. brunnescens (Ag 50) rDNA as a hybridization probe. The rDNA restriction patterns for all six A. brunnescens isolates were identical. The A. bitorquis and A. campestris isolates were subdivided into two groups each, according to rDNA restriction-site polymorphisms. The A. brunnescens and A. bitorquis rDNAs were distinguished by a 0.7 kbp length difference in the noncoding spacer between the 18S and 26S rRNA genes. Despite the almost perfect conservation of the coding region between species, the noncoding spacers of A. campestris and the other two Agaricus species were too divergent to propose a simple series of mutational events to account for the differences. Interstrain and interspecies variation in the mitochondrial DNA was also surveyed. Strain-specific mitochondrial DNA restriction patterns were recognized and fewer differences were observed between the A. brunnescens and A. bitorquis isolates than between A. campestris and the other two species.Key words: Agaricus brunnescens (= A. bisporus), Agaricus, rDNA, mitochondrial DNA, restriction fragment length polymorphism analysis.


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