title: Mitochondrial DNA copy number is maintained during spermatogenesis and in the development of male larvae to sustain the doubly uniparental inheritance of mitochondrial DNA system in the blue mussel Mytilus galloprovincialis.
abstract: Doubly uniparental inheritance (DUI) of mitochondrial (mt) DNA has been reported in the blue mussel Mytilus galloprovincialis. In DUI, males inherit both paternal (M type) and maternal (F type) mtDNA. Here we investigated changes in M type mtDNA copy numbers and mitochondrial mass in testicular cells by real-time polymerase chain reaction and flow cytometry. The ratios of M type mtDNA copy numbers to nuclear DNA content were not different between haploid (1n), diploid (2n) and tetraploid (4n) spermatogenic cells. The mitochondrial mass decreased gradually during spermatogenesis. These results suggest that mtDNA and mitochondrial mass are maintained during spermatogenesis. We then traced M type mtDNA in larvae after fertilization. M type mtDNA was maintained up to 24 h after fertilization in the male-biased crosses, but decreased significantly in female-biased crosses (predicted by Mito Tracker staining pattern). These results are strikingly different from those reported for mammals and fish, where it is well known that the mitochondria and mtDNA are reduced during spermatogenesis and that sperm mitochondria and mtDNA are eliminated soon after fertilization. Thus, the M type mtDNA copy number is maintained during spermatogenesis and in the development of male larvae to sustain the DUI system in the blue mussel.
authors.affiliation: Mie University, Nippon Becton Dickinson Co., Ltd., Shinsenri Higashimachi, Toyonaka-Shi, Osaka, Japan. natsumi5@bio.mie-u.ac.jp
authors.forename: Natsumi
authors.initials: N
authors.lastname: Sano
authors.forename: Mayu
authors.initials: M
authors.lastname: Obata
authors.forename: Yosiyasu
authors.initials: Y
authors.lastname: Ooie
authors.forename: Akira
authors.initials: A
authors.lastname: Komaru
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics; D002499:Centrifugation, Density Gradient; D003433:Crosses, Genetic; D003593:Cytoplasm / Q000235:genetics; D056915:DNA Copy Number Variations; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D005306:Fertilization; D005434:Flow Cytometry; D020459:Genes, rRNA; D040582:Inheritance Patterns; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008297:Male; D008928:Mitochondria / Q000235:genetics*; D049878:Mytilus / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013091:Spermatogenesis; D013094:Spermatozoa / Q000166:cytology; D013194:Staining and Labeling; D013737:Testis / Q000166:cytology / Q000254:growth & development
chemical_list: D004272:DNA, Mitochondrial; D012339:RNA, Ribosomal, 28S