Relationship between time post-ovulation and progesterone on oocyte maturation and pregnancy in canine cloning.

Canine oocytes ovulated at prophase complete meiosis and continue to develop in presence of a high progesterone concentration in the oviduct. Considering that meiotic competence of canine oocyte is accomplished in the oviductal environment, we postulate that hormonal milieu resulting from the circulating progesterone concentration may affect oocyte maturation and early development of embryos. From 237 oocyte donors, 2620 oocytes were collected and their meiotic status and morphology were determined.

Preimplantation development of cloned canine embryos recovered by hysterectomy or surgical uterine flushing and subsequent pregnancy outcomes.

Dog cloning offers a substantial potential because of the advancements in assisted reproductive technology and development of the human disease model in line with the transgenic technique. However, little is known about the development of the canine cloned embryo during the preimplantation period. The aim of this study was to investigate the most efficient method and time for collecting cloned canine preimplantation embryos and to ascertain the developmental timeline of cloned canine embryos.

Stochastic anomaly of methylome but persistent SRY hypermethylation in disorder of sex development in canine somatic cell nuclear transfer.

Somatic cell nuclear transfer (SCNT) provides an excellent model for studying epigenomic reprogramming during mammalian development. We mapped the whole genome and whole methylome for potential anomalies of mutations or epimutations in SCNT-generated dogs with XY chromosomal sex but complete gonadal dysgenesis, which is classified as 78, XY disorder of sex development (DSD). Whole genome sequencing revealed no potential genomic variations that could explain the pathogenesis of DSD.

Influence of somatic cell donor breed on reproductive performance and comparison of prenatal growth in cloned canines.

Using in vivo-flushed oocytes from a homogenous dog population and subsequent embryo transfer after nuclear transfer, we studied the effects of donor cells collected from 10 different breeds on cloning efficiency and perinatal development of resulted cloned puppies. The breeds were categorized into four groups according to their body weight: small (≤9 kg), medium (>9-20 kg), large (>20-40 kg), and ultra large (>40 kg). A total of 1611 cloned embryos were transferred into 454 surrogate bitches for production of cloned puppies.

A canine model of Alzheimer's disease generated by overexpressing a mutated human amyloid precursor protein.

Canines are considered the most authentic model for studying multifactorial human diseases, as these animals typically share a common environment with man. Somatic cell nuclear transfer (SCNT) technology along with genetic engineering of nuclear donor cells provides a unique opportunity for examining human diseases using transgenic canines. In the present study, we generated transgenic canines that overexpressed the human amyloid precursor protein (APP) gene containing well-characterized familial Alzheimer's disease (AD) mutations.

Successful cloning of coyotes through interspecies somatic cell nuclear transfer using domestic dog oocytes.

Interspecies somatic cell nuclear transfer (iSCNT) is an emerging assisted reproductive technology (ART) for preserving Nature's diversity. The scarcity of oocytes from some species makes utilisation of readily available oocytes inevitable. In the present study, we describe the successful cloning of coyotes (Canis latrans) through iSCNT using oocytes from domestic dogs (Canis lupus familiaris or dingo).

Establishment of a canine model of human type 2 diabetes mellitus by overexpressing phosphoenolypyruvate carboxykinase.

Dogs are useful models for studying human metabolic diseases such as type 2 diabetes mellitus due to similarities in physiology, anatomy and life styles with humans. Somatic cell nuclear transfer (SCNT) facilitates the production of transgenic dogs. In this study, we generated transgenic dogs expressing the phosphoenolpyruvate carboxykinase (PEPCK) gene, which is closely involved in the pathogenesis of type 2 diabetes mellitus.

Cloning missy: obtaining multiple offspring of a specific canine genotype by somatic cell nuclear transfer.

The present study was undertaken to evaluate two activation methods for somatic cell nuclear transfer (SCNT), namely, fusion and simultaneous activation (FSA, fusion medium contains calcium), versus fusion followed by chemical activation (F+CA, fusion medium does not contain calcium), and to evaluate the effects of parity of recipient dogs on the success of SCNT. Oocytes retrieved from outbred dogs were reconstructed with adult somatic cells collected from an 11-year-old female dog named Missy. In the FSA method, oocytes were fused and activated at the same time using two DC pulses of 1.

Birth of Beagle dogs by somatic cell nuclear transfer.

The present study was undertaken to evaluate two enucleation methods for somatic cell nuclear transfer (SCNT), and to standardize the optimum number of embryos for transfer to each recipient for canines. Oocytes retrieved from outbreed dogs were reconstructed with adult somatic cells from a male Beagle dog. A total of 134 or 267 oocytes were enucleated either by aspiration or squeezing method, fused with two DC pulses of 1.

Production of cloned dogs by decreasing the interval between fusion and activation during somatic cell nuclear transfer.

To improve the efficiency of somatic cell nuclear transfer (SCNT) in dogs, we evaluated whether or not the interval between fusion and activation affects the success rate of SCNT. Oocytes retrieved from outbred dogs were reconstructed with adult somatic cells from a male or female Golden Retriever. In total, 151 and 225 reconstructed oocytes were transferred to 9 and 14 naturally synchronized surrogates for male and female donor cells, respectively.

Endangered wolves cloned from adult somatic cells.

Over the world, canine species, including the gray wolf, have been gradually endangered or extinct. Many efforts have been made to recover and conserve these canids. The aim of this study was to produce the endangered gray wolf with somatic cell nuclear transfer (SCNT) for conservation.

Improved cryopreservation of bovine preimplantation embryos cultured in chemically defined medium.

The aim of this study was to examine the effects of modifications to a standard slow freezing protocol on the viability of in vitro produced bovine embryos. Bovine oocytes were matured, fertilized with frozen-thawed semen, and presumptive zygotes cultured in defined two-step culture media. The standard freezing medium was 1.