Biomaterial Database

Mitochondrial genotype segregation during preimplantation development in mouse heteroplasmic embryos. 1998

F V Meirelles, and L C Smith

Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.

Mitochondrial DNA content remains constant between the mature egg and the blastocyst stage in mammals, making this the only period in development when genotypes segregate to daughter cells without the confounding effect of genotype replication. To analyze the segregation patterns of mitochondrial DNA during preimplantation development, we introduced polymorphic mitochondria either peripherally (cytoplast transplantation) or in the perinuclear vicinity (karyplast transplantation) into zygotes. Genotype ratios were significantly more variable among blastomeres from cytoplast (coefficient of variation = 83.8%) than karyoplast (coefficient of variation = 34.7%) reconstructed zygotes. These results suggest that heteroplasmy caused by polymorphic mitochondria positioned in the periphery of oocytes at the time of fertilization shows a more stringent segregation pattern than when the organelle is in the vicinity of the nucleus. Moreover, donor-to-host mitochondrial genotype ratios in karyoplast-derived groups increased significantly during development, particularly in the C57BL/6 group, where the ratio practically doubled between the four-cell (17.3%) and the blastocyst stage (29.6%). Although the mechanisms controlling this preferential replication of nuclear-type mitochondrial DNA are unknown, it is suggested that access to nuclear-derived transcription and replication factors could lead to the preferential replication of perinuclear mitochondrial genotypes during morula and blastocyst formation.

UI	MeSH Term	Description	Entries
D008815	Mice, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.	Inbred Mouse Strains,Inbred Strain of Mice,Inbred Strain of Mouse,Inbred Strains of Mice,Mouse, Inbred Strain,Inbred Mouse Strain,Mouse Inbred Strain,Mouse Inbred Strains,Mouse Strain, Inbred,Mouse Strains, Inbred,Strain, Inbred Mouse,Strains, Inbred Mouse
D008845	Microinjections	The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.	Microinjection
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D001755	Blastocyst	A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.	Embryo, Preimplantation,Blastocysts,Embryos, Preimplantation,Preimplantation Embryo,Preimplantation Embryos
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D004272	DNA, Mitochondrial	Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.	Mitochondrial DNA,mtDNA
D005111	Extrachromosomal Inheritance	Vertical transmission of hereditary characters by DNA from cytoplasmic organelles such as MITOCHONDRIA; CHLOROPLASTS; and PLASTIDS, or from PLASMIDS or viral episomal DNA.	Cytoplasmic Inheritance,Extranuclear Inheritance,Inheritance, Cytoplasmic,Inheritance, Extrachromosomal,Inheritance, Extranuclear
D005306	Fertilization	The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.	Conception,Fertilization, Delayed,Fertilization, Polyspermic,Conceptions,Delayed Fertilization,Delayed Fertilizations,Fertilizations,Fertilizations, Delayed,Fertilizations, Polyspermic,Polyspermic Fertilization,Polyspermic Fertilizations
D005838	Genotype	The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.	Genogroup,Genogroups,Genotypes
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia