The Resurrection of Mabrokan: Production of Multiple Cloned Offspring from Decade-Old Vitrified Tissue Collected from a Deceased Champion Show Camel

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Abstract

Somatic cell nuclear transfer (SCNT) provides a unique opportunity to reproduce animals with superior genetics. Viable cell lines are usually established from tissues collected by biopsy from living animals in the SCNT program. In the present study, tissues were collected and preserved from a suddenly deceased champion camel. We established cell lines from these decade-old tissues and used them as nuclear donors. After 42 h of in vitro maturation, 68.00 ± 2.40% of oocytes reached the metaphase II (M II) stage while 87.31 ± 2.57% in vivo collected oocytes were matured at collection (p < 0.05). We observed a higher blastocyst formation rate when in vivo matured oocytes (43.45 ± 2.07%) were used compared to in vitro matured oocytes (21.52 ± 1.74%). The live birth rate was 6.45% vs. 16.67% for in vitro and in vivo matured oocytes, respectively. Microsatellite analysis of 13 camel loci revealed that all the SCNT-derived offspring were identical to each other and with their somatic cell donor. The present study succeeded in the resurrection of 11 healthy offspring from the decade-old vitrified tissues of a single somatic cell donor individual using both in vitro and in vivo matured oocytes.

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Oocyte cytoplasmic maturation: a key mediator of oocyte and embryo developmental competence.

Jennifer Watson (2007)

Efforts have intensified to successfully mature and inseminate oocytes in vitro and then culture ensuing embryos to transferable stages from a large number of mammalian species. Success varies, but generally even for the most successful species it is only possible to obtain a maximum of a 40 to 50% development of zygotes to the blastocyst stage. Reduced oocyte developmental competence is suggested as a primary reason for the reduced potential of in vitro-produced embryos. The vast majority of in vitro-matured oocytes are meiotically competent; however, many do not attain an optimal oocyte diameter before insemination. Variations in oocyte in vitro maturation media can influence embryo development, blastocyst cell number, and apoptosis. In addition, studies have indicated that cytoplasmic donation from so-called competent to incompetent oocytes can improve developmental outcomes. Oocyte cytoplasmic maturation includes those events that instill upon the oocyte a capacity to complete nuclear maturation, insemination, early embryogenesis and thus provide a foundation for implantation, initiation of pregnancy, and normal fetal development. Although we can define oocyte cytoplasmic maturation, we are only now beginning to understand the molecular steps that underlie this process. In general terms, oocyte cytoplasmic maturation involves the accumulation of mRNA, proteins, substrates, and nutrients that are required to achieve the oocyte developmental competence that fosters embryonic developmental competence. Collectively we are beginning to specify oocyte cytoplasmic maturation, and eventually a coherent understanding of this critical event in oocyte biology will emerge.

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Production of the first cloned camel by somatic cell nuclear transfer.

U Wernery, Yasser F. Hassan, R Wernery … (2010)

In this study, we demonstrate the use of somatic cell nuclear transfer to produce the first cloned camelid, a dromedary camel (Camelus dromedarius) belonging to the family Camelidae. Donor karyoplasts were obtained from adult skin fibroblasts, cumulus cells, or fetal fibroblasts, and in vivo-matured oocytes, obtained from preovulatory follicles of superstimulated female camels by transvaginal ultrasound guided ovum pick-up, were used as cytoplasts. Reconstructed embryos were cultured in vitro for 7 days up to the hatching/hatched blastocyst stage before they were transferred to synchronized recipients on Day 6 after ovulation. Pregnancies were achieved from the embryos reconstructed from all cell types, and a healthy calf, named Injaz, was born from the pregnancy by an embryo reconstructed with cumulus cells. Genotype analyses, using 25 dromedary camel microsatellite markers, confirmed that the cloned calf was derived from the donor cell line and the ovarian tissue. In conclusion, the present study reports, for the first time, establishment of pregnancies and birth of the first cloned camelid, a dromedary camel (C. dromedarius), by use of somatic cell nuclear transfer. This has opened doors for the amelioration and preservation of genetically valuable animals like high milk producers, racing champions, and males of high genetic merit in camelids. We also demonstrated, for the first time, that adult and fetal fibroblasts can be cultured, expanded, and frozen without losing their ability to support the development of nuclear transfer embryos, a technology that may potentially be used to modify fibroblast genome by homologous recombination so as to generate genetically altered cloned animals.

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Production of healthy cloned mice from bodies frozen at -20 degrees C for 16 years.

T Hikichi, Eiji Mizutani, Sayaka Wakayama … (2008)

Cloning animals by nuclear transfer provides an opportunity to preserve endangered mammalian species. However, it has been suggested that the "resurrection" of frozen extinct species (such as the woolly mammoth) is impracticable, as no live cells are available, and the genomic material that remains is inevitably degraded. Here we report production of cloned mice from bodies kept frozen at -20 degrees C for up to 16 years without any cryoprotection. As all of the cells were ruptured after thawing, we used a modified cloning method and examined nuclei from several organs for use in nuclear transfer attempts. Using brain nuclei as nuclear donors, we established embryonic stem cell lines from the cloned embryos. Healthy cloned mice were then produced from these nuclear transferred embryonic stem cells by serial nuclear transfer. Thus, nuclear transfer techniques could be used to "resurrect" animals or maintain valuable genomic stocks from tissues frozen for prolonged periods without any cryopreservation.