The consequences of nuclear transfer for mammalian foetal development and offspring survival. A mitochondrial DNA perspective.
The introduction of nuclear transfer (NT) and other technologies that involve embryo reconstruction require us to reinvestigate patterns of mitochondrial DNA (mtDNA) transmission, transcription and replication. MtDNA is a 16.6 kb genome located within each mitochondrion. The number of mitochondria and mtDNA copies per organelle is specific to each cell type. MtDNA is normally transmitted through the oocyte to the offspring. However, reconstructed oocytes often transmit both recipient oocyte mtDNA and mtDNA associated with the donor nucleus. We argue that the transmission of two populations of mtDNA may have implications for offspring survival as only one allele might be actively transcribed. This could result in the offspring phenotypically exhibiting mtDNA depletion-type syndromes. A similar occurrence could arise when nucleo-cytoplasmic interactions fail to regulate mtDNA transcription and replication, especially as the initiation of mtDNA replication post-implantation is a key developmental event. Furthermore, failure of the donor somatic nucleus to be reprogrammed could result in the early initiation of replication and the loss of cellular mtDNA specificity. We suggest investigations should be conducted to enhance our understanding of nucleo-cytoplasmic interactions in order to improve NT efficiency.
St John
Justin C
JC
The Mitochondrial and Reproductive Genetics Group, The Division of Medical Sciences, The Medical School, The University of Birmingham, Birmingham B15 2TT, UK. j.stjohn@bham.ac.uk
Lloyd
Rhiannon E I
RE
Bowles
Emma J
EJ
Thomas
Emma C
EC
El Shourbagy
Shahinaz
S
D000255:Adenosine Triphosphate / Q000378:metabolism; D000483:Alleles; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004261:DNA Replication; D004272:DNA, Mitochondrial; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D008322:Mammals / Q000502:physiology*; D053652:Nuclear Transfer Techniques; D014158:Transcription, Genetic
D004272:DNA, Mitochondrial; D000255:Adenosine Triphosphate