Publications by authors named "Norikazu Miyashita"

Embryonic transfer of bovine blastocysts produced using in vitro fertilization (IVF) is widely used, although the challenge of compromised conception rates remains. Using bovine oviduct epithelial cells (BOEC) to improve embryo culture conditions has attracted attention, particularly since the recent discovery of extracellular vesicles from BOEC. The selection of embryos for transfer has also been the subject of various studies, and a set of evaluation criteria to predict pregnancy success has been suggested, in which the embryos are judged by their kinetics and morphology at the early stages.

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Dolly, the first mammal cloned from a somatic cell, had shorter telomeres than age-matched controls and died at an early age because of disease. To investigate longevity and lifetime performance in cloned animals, we produced cloned cows with short telomeres using oviductal epithelial cells as donor cells. At 5 years of age, despite the presence of short telomeres, all cloned cows delivered multiple healthy offspring following artificial insemination with conventionally processed spermatozoa from noncloned bulls, and their milk production was comparable to that of donor cows.

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In the present study, the growth performance of a calf produced by mating a somatic cell cloned dam and sire was compared with that of its full siblings produced by mating the cattle used as nuclear donors for the cloned animals. The somatic cell cloned dam and sire were derived from cultured cumulus cells and ear cells, respectively. The cloned dam was artificially inseminated with semen from the cloned sire.

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Cytogenetic analysis was performed on peripheral lymphocytes collected from 20 cattle clones (19 showed no overt phenotypic abnormalities except for high birth weight while 1 exhibited left forelimb contracture), the donor cell cultures from which they were derived and lymphocytes from six insemination produced control cattle. All animals and cell cultures had a modal chromosome number of 60. The frequency of abnormal cells for donor cell cultures, clones, and controls was 6.

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We investigated the involvement of caveolin-1 and the cytoskeletal proteins, actin and vimentin, in the adipogenesis of bovine intramuscular preadipocyte (BIP) cells. Immunoblot analysis demonstrated that levels of caveolin-1 and actin gradually increased during adipose conversion in BIP cells, whereas a slight decrease was observed for vimentin. We found that part of the vimentin was clearly distributed to caveolin-1-enriched membrane fractions in BIP cells, but actin was not.

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Interesting questions have been raised regarding cloned animals, including whether cloning restores cellular senescence undergone by donor cells, and how long cloned animals will be able to live. In this study, focusing our attention on the fact that telomere lengths of spermatozoa are longer than those of any somatic cells and that telomere length is maintained throughout aging in humans, we compared the telomere lengths of spermatozoa in normal and two somatic cell-cloned cattle. The telomere lengths of the spermatozoa in the normal cattle (22.

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Regarding cloned animals, interesting questions have been raised as to whether cloning restores cellular senescence undergone by their donor cells and how long cloned animals will be able to live. Focusing our attention on differences in telomere lengths depending on the tissue, we had produced 14 cloned cattle by using nuclei of donor cells derived from muscle, oviduct, mammary, and ear skin. Here, we show remarkable variation in telomere lengths among them using Southern blot analysis with telomere-specific probe.

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