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To elucidate the genetic basis of reproductive seasonality in Spanish Merino sheep breed, a genome-wide association study (GWAS) in order to detect single nucleotide polymorphisms (SNPs) or regions associated with resumption of ovarian cyclicity during the postpartum period in conjunction with the seasonal anestrus was performed. In total, 169 multiparous Merino ewes which lambed in February were genotyped using the 50k Illumina Ovine Beadchip. After of lambing, blood samples were obtained weekly for measurement of peripheral progesterone concentrations from day 45 to 120. At 72 days of age, lambs were weaned. Live weight, and body condition score of the ewes were also measured. The days from lambing to ovarian activation trait was used for GWAS. An ewe was considered cyclic when the progesterone concentration was higher than or equal to the threshold of 0.5 ng/mL. GCTA software was used for GWAS analysis. Only one SNP (rs161969506) overcame the genome-wide significance level (p_Bonferroni < 0.05) on chromosome 3. Six potential SNPs overcame the chromosome-wise significance level (p_FDR < 0.05). The SNP rs161969506 was located in intron 7 of the KDM3A candidate gene in Oar_Rambouillet 1.0. KDM3A is a demethylase enzyme that has been identified as key regulator of a number of transcription factors, including androgen receptors in the ovary. This gene was partial isolated and Sanger-sequenced, and 5 SNPs were found: 1 SNP in promoter region and 4 nonsynonymous polymorphisms in exons 10 and 17. One and 2 SNPs in promoter and exon 10, respectively, were associated with the studied phenotype in the GWAS population. Haplotype association analysis confirmed the implication of this gene in the studied trait.

Contents In vitro oocyte maturation can be influenced by oocyte source and maturation media composition. The aim of the present study was to compare the efficiency of a defined in vitro maturation medium (TCM199 supplemented with cysteamine and epidermal growth factor; Cys+EGF) with an undefined medium (TCM199 supplemented with follicle-stimulating hormone and follicular fluid; FSH+FF) for in vitro production (IVP) of ovine embryos, using oocytes obtained by laparoscopic ovum pick-up from FSH-stimulated [n=11; 158 cumulus-oocyte complexes (COCs)] and non-stimulated (n=16; 120 COCs) live ewes, as well as abattoir-derived oocytes (170 COCs). The produced blastocysts were vitrified and some of them were transferred to synchronized recipients. The best and the worst final yields of embryo IVP observed in this study were obtained using oocytes from FSH-stimulated ewes matured in FSH+FF (41.3%; 33/80) and in Cys+EGF (19.2%; 15/78) medium, respectively (p<0.01). No significant differences between both media were attained in the blastocyst development rate or in the final yield of embryo IVP using oocytes from non-stimulated ewes or abattoir-derived oocytes. The overall in vivo survival rate of the transferred vitrified blastocysts was 13.1% (8/61), without significant differences between oocyte sources or maturation media. In conclusion, under the experimental conditions of the present study, TCM199 supplemented with cysteamine and EGF is a convenient defined maturation medium for IVP of embryos from oocytes of live non-stimulated ewes or from oocytes of abattoir-derived ovaries. However, the best final yield of embryo IVP observed in this study was attained when oocytes came from FSH-stimulated donors and TCM199 was supplemented with FSH and follicular fluid. © 2010 Blackwell Verlag GmbH.

Two experiments have been performed to clone the bucardo, an extinct wild goat. The karyoplasts were thawed fibroblasts derived from skin biopsies, obtained and cryopreserved in 1999 from the last living specimen, a female, which died in 2000. Cytoplasts were mature oocytes collected from the oviducts of superovulated domestic goats. Oocytes were enucleated and coupled to bucardo's fibroblasts by electrofusion. Reconstructed embryos were cultured for 36 h or 7 d and transferred to either Spanish ibex or hybrid (Spanish ibex male × domestic goat) synchronized recipients. Embryos were placed, according to their developmental stage, into the oviduct or into the uterine horn ipsilateral to an ovulated ovary. Pregnancy was monitored through their plasmatic PAG levels. In Experiment 1, 285 embryos were reconstructed and 30 of them were transferred at the 3- to 6-cells stage to 5 recipients. The remaining embryos were further cultured to day 7, and 24 of them transferred at compact morula/blastocyst stage to 8 recipients. In Experiment 2, 154 reconstructed embryos were transferred to 44 recipients at the 3- to 6-cells stage. Pregnancies were attained in 0/8 and 7/49 of the uterine and oviduct-transferred recipients, respectively. One recipient maintained pregnancy to term, displaying very high PAG levels. One morphologically normal bucardo female was obtained by caesarean section. The newborn died some minutes after birth due to physical defects in lungs. Nuclear DNA confirmed that the clone was genetically identical to the bucardo's donor cells. To our knowledge, this is the first animal born from an extinct subspecies. © 2009.

Bone morphogenetic protein 15 (BMP15) is a member of the transforming growth factor beta superfamily, is specifically expressed in oocytes and is essential for sheep prolificacy. Reported mutations in this gene cause increased ovulation rate and infertility in a dosagesensitive manner. In this work, a new naturally occurring mutation in the BAP15 gene from the ovine Rasa Aragonesa breed is described. This mutation is a deletion of 17 bp that leads to an altered amino acid sequence and introduces a premature stop codon in the protein. Highly significant associations (P < 0.0001) were found between the estimated breeding value for prolificacy and the genotype of BMP15 in Rasa Aragonesa animals with high and low breeding values for this trait. As for other mutations in BMP15, this new mutation is associated with increased prolificacy and sterility in heterozygous and homozygous ewes respectively. © 2008 International Society for Animal Genetics.