Birth of African Wildcat Cloned Kittens Born from Domestic Cats

Abstract

In the present study, we used the African Wildcat (Felis silvestris lybica) as a somatic cell donor to evaluate the in vivo developmental competence, after transfer into domestic cat recipients, of cloned embryos produced by the fusion of African Wildcat (AWC) fibroblast cell nuclei with domestic cat cytoplasts. Cloned embryos were produced by fusion of a single AWC somatic cell to in vivo or in vitro enucleated domestic cat cytoplasts. When the two sources of oocytes were compared, fusion rate was higher using in vivo-matured oocytes as recipient cytoplasts, but cleavage rate was higher after reconstruction of in vitro-matured oocytes. To determine the number of reconstructed embryos required per domestic cat recipient to consistently establish pregnancies, AWC cloned embryos were transferred within two groups: recipients (n = 24) receiving < or =25 embryos and recipients (n = 26) receiving > or =30 embryos. Twelve recipients (46.2%) receiving > or =30 embryos were diagnosed to be pregnant, while no pregnancies were established in recipients receiving < or =25 NT embryos. Also, to determine the influence of length of in vitro culture on pregnancy rate, we compared oviductal transfer on day 1 and uterine transfer on day 5, 6, or 7. Pregnancy rates were similar after transfer of embryos on day 1 (6/12; 50.0%), day 5 (4/9; 44.4%), or day 6 (2/5; 40.0%) to synchronous recipients, but the number of fetuses developing after transfer of embryos on day 1 (n = 17), versus day 5 (n = 4) or day 6 (n = 3) was significantly different. Of the 12 pregnant recipients, nine (75%) developed to term and fetal resorption or abortion occurred in the other three (25%) from day 30 to 48 of gestation. Of a total of 17 cloned kittens born, seven were stillborn, eight died within hours of delivery or up to 6 weeks of age, and two are alive and healthy. Perinatal mortality was due to lung immaturity at premature delivery, placental separation and bacterial septicemia. Subsequent DNA analysis of 12 cat-specific microsatellite loci confirmed that all 17 kittens were clones of the AWC donor male. These AWC kittens represent the first wild carnivores to be produced by nuclear transfer.

Full-term delivery of river buffalo calves (2n=50) from in vitro-derived vitrified embryos by swamp buffalo recipients (2n=48)

“…However, the relationship of the difference in chromosome number on efficiency rate has not been fully elucidated. Nonetheless, there have been reports on the success of inter-species embryo transfer of endangered species (Gomez et al, 2004). This suggests that the difference in chromosome number, at least in water buffalo species, is not the major factor affecting the current efficiency rate, but other compounding factors brought about by the embryo, the recipients and the techniques per se.…”

Aberrant profile of gene expression in cloned mouse embryos derived from donor cumulus nuclei

“…To date, mammalian species that have been successfully cloned by SCNT include sheep (Campbell et al 1996;McCreath et al 2000), mouse (Wakayama et al 1998(Wakayama et al -2000Wakayama et al 2005a;Ogura et al 2000;Yanagimachi 1999, 2001), goat (Baguisi et al 1999;Keefer et al 2002;Landry et al 2005), cattle (Kasinathan et al 2001;Sullivan et al 2004;Gong et al 2004a,b), pig (Polejaeva et al 2000;Betthauser et al 2000;Yin et al 2002;Ramsoondar et al 2003;Hyun et al 2003;Lee et al 2003), cat (Gomez et al 2004;Yin et al 2005), rabbit (Chesne et al 2002;Matsuda et al 2002;ChallahJacques et al 2003), horse (Galli et al 2003), banteng (Sansinena et al 2005), guar (Vogel 2001), rat (Zhou et al 2003), and dog (Lee et al 2005). In addition to the production of viable live offspring, cloned cattle (Cibelli et al 1998) and mouse (Wakayama et al 2005b;Kawase et al 2000;Wakayama 2003) embryos have also been used to generate embryonic stem cell lines, in what is referred to as "therapeutic cloning".…”

Progenitor Cells for Regenerative Medicine and Consequences of ART and Cloning-Associated Epimutations

“…In 1997, the ability of a differentiated mammalian somatic genome to direct embryonic development-following reprogramming by the recipient oocyte-was illustrated by the successful birth of Dolly, the first mammalian clone using an adult cell as the source of the donor nucleus [117]. Since then, live births have resulted from SCNT using nuclei from adult cells in numerous mammalian species, including examples of interspecies nuclear transfer in endangered species [16,118,119]. While these achievements suggest that, theoretically, it is possible to clone almost any species using donor nuclei from almost any cell type, the efficiency of SCNT remains low.…”