Reproduction in female yaks (Bos grunniens) and opportunities for improvement

Zi, Xiang-Dong

doi:10.1016/s0093-691x(02)01172-x

Cited by 100 publications

(77 citation statements)

References 8 publications

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“…Their reproductive rate is lower (40-60%) than other mammals (Sarkar and Prakash, 2005;Yu and Li, 2001;Zi, 2003). Therefore, it is very important to improve the reproductive efficiency of yaks by techniques of in vitro embryo production and SCNT (Karatzas et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Recombinant Human Bone Morphogenetic Protein 6 Enhances Oocyte Reprogramming Potential and Subsequent Development of the Cloned Yak Embryos

Cui

Baloch

et al. 2015

Cellular Reprogramming

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This study investigated the effects of bone morphogenetic protein 6 (BMP6) supplementation in the medium during in vitro maturation (IVM) on the developmental potential of oocytes and in the subsequent development of cloned yak embryos. Cumulus-oocyte complexes (COCs) were aspirated from the antral follicles of yak ovaries and cultured with different concentrations of recombinant human BMP6 in oocyte maturation medium. Following maturation, the metaphase II (MII) oocytes were used for somatic cell nuclear transfer (SCNT), and these were cultured in vitro. The development of blastocysts and cell numbers were detected on day 8. The apoptosis and histone modifications of yak cloned blastocysts were evaluated by detecting the expression of relevant genes and proteins (Bax, Bcl-2, H3K9ac, H3K18ac, and H3K9me3) using relative quantitative RT-PCR or immunofluorescence. The presence of 100 ng/mL BMP6 significantly enhanced the oocyte maturation ratios (66.12 -2.04% vs. 73.11 -1.38%), cleavage rates (69.40 -1.03% vs. 78.16 -0.93%), and blastocyst formation rates (20.63 -1.32% vs. 28.16 -1.67%) of cloned yak embryos. The total blastocysts (85.24 -3.12 vs. 103.36 -5.28), inner cell mass (ICM) cell numbers (19.59 -2.17 vs. 32.20 -2.61), and ratio of ICM to trophectoderm (TE) (22.93 -1.43% vs. 31.21 -1.62%) were also enhanced ( p < 0.05). The ratio of the Bax to the Bcl-2 gene was lowest in the SCNT + BMP6 groups ( p < 0.05). The H3K9ac and H3K18ac levels were increased in SCNT + BMP6 groups ( p < 0.05), whereas the H3K9me3 level was decreased; the differences in blastocysts were not significant ( p > 0.05). These study results demonstrate that addition of oocyte maturation medium with recombinant BMP6 enhances yak oocyte developmental potential and the subsequent developmental competence of SCNT embryos, and provides evidence that BMP6 is an important determinant of mammalian oocyte developmental reprogramming.

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Section: Discussionmentioning

confidence: 99%

Recombinant Human Bone Morphogenetic Protein 6 Enhances Oocyte Reprogramming Potential and Subsequent Development of the Cloned Yak Embryos

Cui

Baloch

et al. 2015

Cellular Reprogramming

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“…Many studies have shown that pregnancy rates are above 70% if female yak are mated with yak bulls [1,5,17,18]. However, when the yak female is inseminated (naturally or artificially) with semen from Bos taurus or Bos indicus, the pregnancy rate falls [3,5].…”

Section: Discussionmentioning

confidence: 99%

Developmental Competence of Embryos Derived from Reciprocal In Vitro Fertilization between Yak (Bos grunniens) and Cattle (Bos taurus)

Yin

Chen

et al. 2009

Journal of Reproduction and Development

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Abstract. The purpose of this study was to investigate fertilization ability and embryo development to the blastocyst stage after reciprocal in vitro fertilization (IVF) between yak and cattle in an attempt to clarify the problem of low conception rate after mating yak females with cattle bulls. In vitro-matured (IVM) cattle and yak oocytes were inseminated with either Holstein or yak spermatozoa, and after an 18-h of coincubation period, a proportion of the oocytes was fixed and examined for sperm penetration, polyspermy and male pronuclear formation. The remaining oocytes were cultured in vitro and evaluated for cleavage and blastocyst formation rates. The percentage of IVM oocytes penetrated by spermatozoa ranged from 78.5 to 90.5%, and the formation of one or two pronuclei and the incidence of polyspermy did not differ among the different combinations. The cleavage and blastocyst rates were not affected by the species of the sperm, but they were affected by the species of the oocytes (P<0.05), with cattle oocytes having a higher (P<0.05) cleavage and blastocyst rates (69.9 and 31.3%) than yak oocytes (62.7 and 11.5%). The blastocyst formation rate was calculated from the cleaved zygotes. The interaction between sire and oocytes species (P<0.05) influenced blastocyst formation rate, with the highest blastocyst rate occurring in cattle oocytes fertilized with yak spermatozoa (36.5%) and the lowest rate occurring in yak oocytes fertilized with yak spermatozoa (9.4%). The effect of heterosis was apparent at the blastocyst stage, but there was a large reciprocal difference in blastocyst production between crosses. It was concluded that the low conception rate that results from crossing yaks with cattle is not due to either a speciesspecific block of fertilization or the developmental competence of the early stage embryo. Key words: Cattle, Early development, Embryos, In vitro fertilization (IVF), Yak (J. Reprod. Dev. 55: [480][481][482][483] 2009) he yak is one of the world's most remarkable domestic animals -a herbivore living on the "roof of the world", in and around the Himalayas and further north at altitudes ranging from 2500 to 5500 m with no frost-free period and mostly above the tree line. They are very important to local people for meat, milk and draft power given that few other animals survive in these areas. However, their production traits are inferior to those of improved cattle (Bos taurus) breeds [1,2].Interest in the commercial use of local cattle × yak hybrids has existed for at least 3000 years. During this time, attempts have been made to improve meat and milk production (quoted from Wiener et al. [1]). A number of systematic studies carried out from 1950s to 1990s have examined the meat and milk performance of hybrids of yak derived from both natural mating and artificial insemination using semen from exotic breeds of cattle such as the Holstein, Simmental, Hereford and Shorthorn. The results have shown that F1 hybrids from dairy cattle breeds produce 100-300% more milk than the yak [3,4]. ...

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“…The yak is a seasonal breeder with a low reproductive rate and milk yield compared with dairy cattle breeds (Zi, 2003;Sarkar et al, 2005;Reiter et al, 2009). Previous studies have shown that and ovary during the breeding season in yak, indicating that melatonin may have a critical role in hormonal production during the yak breeding season.…”

Section: Discussionmentioning

confidence: 99%

Melatonin receptor (MTNR1A and MTNR2B) expression during the breeding season in the yak (Bos grunniens)

Huo¹,

Long²

2014

CZECH J ANIM SCI

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ABSTRACT:Melatonin plays key roles in a wide range of mammalian body functions, which are mediated by the melatonin-specific cell surface receptor (MTNR1A and MTNR1B). To better understand the role of MTNR in the yak (Bos grunniens), we determined the melatonin receptor mRNA expression level. The analysis showed that the MTNR mRNA expression level was higher in the pineal gland tissue than in the hypothalamus, pituitary gland, and ovary (P < 0.01) during the breeding season. Immunofluorescence analyses showed that yak MTNR was located in the pinealocyte, synaptic ribbon, and synaptic spherules of the pineal gland and that melatonin interacts via nerve fibres. In the hypothalamus, MTNR was located in the magnocellular neurons and parvicellular neurons. MTNR was localized in acidophilic cells and basophilic cells in the pituitary gland. In the ovary, MTNR was present in the ovarian follicle, corpus luteum, and Leydig cells.

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Reproduction in female yaks (Bos grunniens) and opportunities for improvement

Cited by 100 publications

References 8 publications

Recombinant Human Bone Morphogenetic Protein 6 Enhances Oocyte Reprogramming Potential and Subsequent Development of the Cloned Yak Embryos

Recombinant Human Bone Morphogenetic Protein 6 Enhances Oocyte Reprogramming Potential and Subsequent Development of the Cloned Yak Embryos

Developmental Competence of Embryos Derived from Reciprocal In Vitro Fertilization between Yak (Bos grunniens) and Cattle (Bos taurus)

Melatonin receptor (MTNR1A and MTNR2B) expression during the breeding season in the yak (Bos grunniens)

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