Publications by authors named "Yuichi Kameyama"

The emu (Dromaius novaehollandiae) is a novel poultry species that produces meat, eggs, and fat. Although emus have recently been domesticated, genetic improvements to establish strains have scarcely progressed. In this study, we investigated the relationship between production traits and perilipin 1-encoding gene (PLIN1) polymorphisms in the emus.

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  • * To address this, the study analyzed the genetic structure of six Japanese emu farms using mitochondrial DNA and microsatellite techniques, finding significant genetic differentiation among populations.
  • * The research identified four distinct genetic groups within these emu populations, providing valuable insights that could help enhance genetic diversity and support population conservation in Japanese farms.
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Fibroblast growth factor 5 (FGF5) is an important molecule required for the transition from anagen to catagen phase of the mammalian hair cycle. We previously reported that Syrian hamsters harboring a 1-bp deletion in the Fgf5 gene exhibit excessive hair growth in males. Herein, we generated Fgf5 mutant mice using genome editing via oviductal nucleic acid delivery (GONAD)/improved GONAD (i-GONAD), an in vivo genome editing system used to target early embryos present in the oviductal lumen, to study gender differences in hair length in mutant mice.

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  • Carcass traits and fat quality in emus were analyzed, revealing that female emus had significantly higher meat production compared to males, while males had greater fat weight.
  • Fat yield was strongly correlated with body weight in both sexes, and the fat melting points for males and females were similar, suggesting a genetic influence rather than body size.
  • The study noted significant variability in linoleic acid content and identified a negative correlation between the oleic/stearic acid ratio and fat melting point, indicating that the melting point may serve as an indicator for fat composition in emus.
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Purpose: Post-ovulatory aging causes a high frequency of aneuploidy during meiosis II in mouse oocytes, irrespective of maternal age. In this study, we evaluated the effects of post-ovulatory oocyte aging on the protection of chromosomal cohesion involved in aneuploidy and verified the relationship between PP2A or SGO2 expression and the phosphorylation level of REC8 in oocytes.

Methods: Murine ovulated oocytes were incubated for 6 or 12 h after collection and denoted as the aged group.

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The emu is a useful and new breed of poultry, but their genetic improvement has not advanced yet due to their very recent domestication. Pedigree information is difficult to record because of their complex reproduction system (polyandry). To identify parent-offspring relationships in the emu, parentage test based on polymorphic DNA markers have to be developed.

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  • The study analyzed the mitochondrial DNA of emus in Japan, focusing on their haplotype composition with 109 individuals sequenced in the D-loop region.
  • Researchers identified four substitution sites and three haplotypes (Hap-a, -b, and -c), with Hap-a being the most common among Japanese emus.
  • The findings revealed significant genetic differentiation among populations and suggest that these insights could help conserve genetic resources for the emu industry in Japan.
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The emu (Dromaius novaehollandiae) is a useful poultry animal farmed for fat, meat, and eggs. Genetic structure and relationships among farmed emu populations in Japan are unknown and the number of microsatellite markers for genetic analysis of the emu is insufficient. In this study, we isolated 16 microsatellites from the emu genome and developed ten new microsatellite markers.

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Mammalian oocyte quality degrades over time after ovulation in vitro, which can cause fatal defects such as chromosomal aneuploidy. As various oocyte manipulations employed in assisted reproductive technology are time consuming, post-ovulatory aging is a serious problem to overcome in reproductive medicine or ova research. In this study, we investigated the effects of postovulatory aging on the incidence of chromosome aneuploidy during meiosis II, with a focus on the expression of functional proteins from the spindle assembly checkpoint (SAC).

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  • Hair length in mammals is controlled by the hair cycle; disruptions in this cycle can result in abnormal hair growth patterns due to specific gene mutations, like in FGF5.
  • A study of the long-haired Syrian hamster strain (MALC) showed that testosterone affects hair length; castration led to shorter hair, but reintroducing testosterone restored the long-haired phenotype.
  • The identified mutation (Fgf5malc) in MALC affects the hair growth phase, making males have longer hair because of a prolonged growth period influenced by testosterone; this is the first report linking a gene mutation to sexual differences in hair length.
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A recent report showed higher oxygen consumption, adenosine triphosphate (ATP) production and mitochondrial localisation in trophectoderm cells than in the inner cell mass of mouse blastocysts. We hypothesised that this phenomenon was due to the asymmetrical distribution of mitochondria in the blastomeres during the earlier stages. Oocytes, 2-cell embryos and 4-cell embryos were analysed to determine the volume, ATP content and mitochondrial DNA (mtDNA) copy number in the whole egg and individual blastomeres.

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  • In vitro culture (IVC) is a key technique in reproductive technologies but imposes stress on embryos, affecting mitochondrial function.
  • The study measured mtDNA copy numbers and mitochondrial gene mRNA levels in rat oocytes and embryos, finding that IVC increased mtDNA copy number starting from the 8-cell stage.
  • Results indicate that IVC disrupts normal mitochondrial transcription and mtDNA replication control, which could lead to physiological and developmental issues in embryos created through these methods.
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In vivo studies for understanding viral transmission and replication, host immune responses, and pathogenesis of human immunodeficiency virus type 1 (HIV-1) infection would greatly benefit from the establishment of a small-animal model. In this study, we explored the potential of American mink (Mustera vison) as a susceptible host. We found that primary cells and cell lines derived from this species efficiently supported trans-activation of the HIV-1 long terminal repeat by Tat.

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