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Characterization of mitochondrial DNA in chloramphenicol-resistant interspecific hybrids and a cybrid
Abstract:
We have examined the restriction endonuclease cleavage patterns exhibited by the mitochondrial DNAs (mtDNA) of four chloramphenicol-resistant (CAPR) human x mouse hybrids and one CAPR cybrid derived from CAPR HeLa cells and CAPS mouse RAG cells. Restriction fragments of mtDNAs were separated by electrophoresis and transferred by the Southern technique to diazobenzyloxymethyl paper. The covalently bound DNA fragments were hybridized initially with 32P-labeled complementary RNA (cRNA) prepared from human mtDNA and, after removal of the human probe, hybridized with mouse [32P]cRNA prepared from mouse mtDNA. Three hybrids which preferentially segregated human chromosomes and the cybrid exhibited mtDNA fragments indistinguishable from mouse cells. One hybrid, ROH8A, which exhibited "reverse" chromosome segregation, contained only human mtDNA. The pattern of chromosome and mtDNA segregation observed in these hybrids and the cybrid support the hypothesis that a complete set of human chromosomes must be retained if a human-mouse hybrid is to retain human mitochondrial DNA.
Insights
Human chromosome retention is essential for maintaining human mitochondrial DNA (mtDNA) in human-mouse hybrids. Hybrids lacking human chromosomes lost human mtDNA, indicating a dependency for its persistence.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- Mitochondrial DNA (mtDNA) plays a crucial role in cellular energy production.
- Understanding the inheritance patterns of mtDNA in interspecies hybrids is vital for genetic research.
- Previous studies have suggested a link between nuclear chromosomes and mtDNA stability.
Purpose of the Study:
- To investigate the restriction endonuclease cleavage patterns of mitochondrial DNAs (mtDNAs) in chloramphenicol-resistant (CAPR) human x mouse hybrids and cybrids.
- To determine the relationship between chromosome segregation and mtDNA retention in these hybrids.
- To test the hypothesis that a complete set of human chromosomes is required for human mtDNA persistence.
Main Methods:
- Analysis of restriction endonuclease cleavage patterns of mtDNAs from human x mouse hybrids and cybrids.
- Separation of mtDNA restriction fragments via electrophoresis.
- Southern blot technique for DNA transfer, followed by hybridization with human and mouse mtDNA-specific complementary RNA (cRNA) probes.
Main Results:
- Three hybrids and one cybrid, which preferentially segregated human chromosomes, displayed mtDNA fragments identical to mouse cells.
- One hybrid (ROH8A), exhibiting reverse chromosome segregation, exclusively contained human mtDNA.
- The observed segregation patterns of chromosomes and mtDNA support a dependency of human mtDNA on the retention of human chromosomes.
Conclusions:
- The presence of human mitochondrial DNA (mtDNA) in human-mouse hybrids is contingent upon the retention of a complete set of human chromosomes.
- This finding supports the hypothesis that nuclear-encoded factors, likely carried on human chromosomes, are necessary for the maintenance and replication of human mtDNA.
- The study provides critical insights into the complex interplay between nuclear and mitochondrial genomes in hybrid cells.