Mitochondrial DNA content and mitochondrial gene transcriptional activities in the early development of loach and goldfish.
The mitochondrial DNA (mtDNA) content of the mature eggs and embryos of loach and goldfish at early developmental stages were detected by means of dot hybridization. The transcription of mitochondrial cytochrome oxidase subunit I and II (COI and COII) genes during their early development was also detected by Northern hybridization. The experimental results showed that the mtDNA content of the mature egg as well as that of the embryos during the period from fertilized egg up to hatching stage in both fishes is maintained at a constant level, giving an average value of 7.40 x 107 molecules or 1.33 ng for every embryo in loach and an average value of 1.87 x 10(8) molecules or 3.31 ng for every embryo in goldfish. In both fish embryos, the COI and COII transcripts declined gradually after fertilization until late-blastula stage and then increased in early gastrula stage. This indicated that the transcription of mitochondrial genomes of these two freshwater fishes, which belong to different families, might be activated at the beginning of gastrulation. The steady-state amounts of mitochondrial messenger transcripts existing in the embryos during the early development in both fishes seemed to be regulated by both their half-lives and the transcriptional level of the mitochondrial genomes. The results showed that the transcription of the mitochondrial genome in the early developmental process in loach and goldfish was not regulated by a gene dosage mechanism.
Wang
G
G
Institute of Developmental Biology, Chinese Academy of Sciences, Beijing.
Yan
S
S
D000818:Animals; D003531:Cypriniformes / Q000196:embryology*; D004272:DNA, Mitochondrial / Q000032:analysis*; D004303:Dosage Compensation, Genetic; D003576:Electron Transport Complex IV / Q000096:biosynthesis; D006054:Goldfish / Q000196:embryology*; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic
D004272:DNA, Mitochondrial; D012333:RNA, Messenger; D003576:Electron Transport Complex IV