title: Heteroplasmy in bovine fetuses produced by intra- and inter-subspecific somatic cell nuclear transfer: neutral segregation of nuclear donor mitochondrial DNA in various tissues and evidence for recipient cow mitochondria in fetal blood.
abstract: Varying degrees of mitochondrial DNA (mtDNA) heteroplasmy have been observed in nuclear transfer embryos, fetuses, and offspring, but the mechanisms leading to this condition are unknown. We have generated a clone of 12 bovine somatic cell nuclear transfer fetuses, using nuclear donor cells, recipient oocytes, and recipient heifers with defined mtDNA genotypes, to study nuclear-mitochondrial interactions and the origins of mtDNA heteroplasmy. Embryos were reconstructed from granulosa cells with Bos taurus mtDNA type A and recipient oocytes collected from three different maternal lineages with B. taurus mtDNA type B, B. taurus mtDNA type C, or B. indicus mtDNA. Sequence differences in the control region (CR) of B. taurus mtDNAs ranged from 6 to 11 nucleotides and differences between B. taurus and B. indicus CRs from 45 to 50 nucleotides. Fetuses were recovered from recipient heifers with B. taurus mtDNA type B on Day 80 after nuclear transfer (eight B. taurus A/B, two B. taurus A/C, and two B. taurus A/B. indicus). Agarose gel analysis of the CR by polymerase chain reaction-based restriction fragment length polymorphism failed to detect nuclear donor mtDNA in 11 investigated tissues of 10 viable fetuses and in DNA samples of two fetuses in resorption (one B. taurus A/B and one B. taurus A/C). A more sensitive analysis of 1801 plasmid clones with CR inserts derived from tissues of a B. taurus A/B. indicus fetus detected no or very low levels of heteroplasmy (0.5-0.7%). However, the analyses detected considerable amounts ( approximately 2.5% and 5%) of recipient heifer mtDNA in blood samples from two fetuses. Our data do not suggest a replicative advantage of somatic nuclear donor cell mtDNA in bovine transmitochondrial clones produced with oocytes from domestic forms of the same or a different aurochs (B. primigenius) subspecies. Detection of mtDNA from the recipient animal in the circulation of two fetuses points to leakage of the placental barrier, mimicking heteroplasmy.
authors.affiliation: Department of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilian University, D-85764 Oberschleissheim, Germany. s.hiendleder@gen.vetmed.uni-muenchen.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Hiendleder
authors.forename: Valeri
authors.initials: V
authors.lastname: Zakhartchenko
authors.forename: Hendrik
authors.initials: H
authors.lastname: Wenigerkind
authors.forename: Horst-Dieter
authors.initials: HD
authors.lastname: Reichenbach
authors.forename: Katja
authors.initials: K
authors.lastname: Brüggerhoff
authors.forename: Katja
authors.initials: K
authors.lastname: Prelle
authors.forename: Gottfried
authors.initials: G
authors.lastname: Brem
authors.forename: Miodrag
authors.initials: M
authors.lastname: Stojkovic
authors.forename: Eckhard
authors.initials: E
authors.lastname: Wolf
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D019976:Cloning, Organism; D004272:DNA, Mitochondrial / Q000097:blood* / Q000235:genetics*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005838:Genotype; D008431:Maternal-Fetal Exchange; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D053652:Nuclear Transfer Techniques; D011247:Pregnancy; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014018:Tissue Distribution
chemical_list: D004272:DNA, Mitochondrial