Interspecies Implantation and Mitochondria Fate of Panda-Rabbit Cloned Embryos1

Abstract

Somatic cell nuclei of giant pandas can dedifferentiate in enucleated rabbit ooplasm, and the reconstructed eggs can develop to blastocysts. In order to observe whether these interspecies cloned embryos can implant in the uterus of an animal other than the panda, we transferred approximately 2300 panda-rabbit cloned embryos into 100 synchronized rabbit recipients, and none became pregnant. In another approach, we cotransferred both panda-rabbit and cat-rabbit interspecies cloned embryos into the oviducts of 21 cat recipients. Fourteen recipients exhibited estrus within 35 days; five recipients exhibited estrus 43-48 days after embryo transfer; and the other two recipients died of pneumonia, one of which was found to be pregnant with six early fetuses when an autopsy was performed. Microsatellite DNA analysis of these early fetuses confirmed that two were from giant panda-rabbit cloned embryos. The results demonstrated that panda-rabbit cloned embryos can implant in the uterus of a third species, the domestic cat. By using mitochondrial-specific probes of panda and rabbit, we found that mitochondria from both panda somatic cells and rabbit ooplasm coexisted in early blastocysts, but mitochondria from rabbit ooplasm decreased, and those from panda donor cells dominated in early fetuses after implantation. Our results reveal that mitochondria from donor cells may substitute those from recipient oocytes in postimplanted, interspecies cloned embryos.

Nuclear–cytoplasmic incompatibility and inefficient development of pig–mouse cytoplasmic hybrid embryos

“…Our results were not different from several other recent reports (Chung et al 2009, Lagutina et al 2010, who had also reported that iSCNT embryos failed to reactivate the embryonic genome and arrested at the stage of EGA specific to the recipient oocyte. Conversely, inter-genus (Oh et al 2006, Yin et al 2006, inter-family (Dominko et al 1999, Zhao et al 2007, inter-order (Yang et al 2003, Wen et al 2005, Illmensee et al 2006, and even inter-class iSCNT (Chen et al 2002, Liu et al 2004 nuclear transfer embryos were reported to have Pig-mouse cytoplasmic hybrid embryos developed to the blastocyst stage. However, these later reports also observed that the majority of iSCNT embryos arrested around the stage of EGA and only a very small percent of embryos developed to blastocyst stage.…”

Des ovules en abondance ?

“…Ce bricolage a été réalisé avec succès, dans le cadre de la préservation d'animaux menacés, pour des espèces très proches: croisements mouflon/mouton [23] ou bovin sauvage (Bos javanicus)/bovin domestique (Bos taurus) [24]. Des auteurs chinois ont même tenté de conserver ainsi le panda géant, mais leur expérience audacieuse (génome de panda introduit dans l'ovule de lapin et gestation de l'embryon chimérique assurée par une chatte…) n'a pas conduit à la naissance, bien que le dévelop-pement post-implantatoire, chez la chatte, de clones interspé-cifiques panda-lapin soit rapporté [25]. Le modèle interspécifique pourrait se révéler plus efficace si la folliculogenèse elle-même était assurée au sein d'un organisme animal.…”

Increased Th1/Th2 (IFN-.GAMMA./IL-4) Cytokine mRNA Ratio of Rat Embryos in the Pregnant Mouse Uterus

“…In our laboratory, we have r e c o n s t r u c t e d a p p r o x i m a t e l y 2 3 0 0 p a n d a (Ailuropoda melanoleuca, a highly endangered species) -rabbit interspecific cloned embryos and transferred them into the oviducts of 100 recipient cats. We found that panda-rabbit cloned embryos could be implanted into the uteri of a third species, but pregnancies were lost after 45 days [10]. The high failure rate of interspecific pregnancies has become a major obstacle to successful interspecific cloning.…”

“…So, interspecific SCNT (iSCNT) has been explored to produce cloned offspring, and usually includes interspecific somatic cell nuclear transfer and interspecific pregnancy. In previous research, the oocytes of bovine, sheep, and rabbits have been used for iSCNT, and interspecific reconstructed embryos have been obtained [5][6][7][8][9][10][11][12][13]. Interspecific r e c o n s t r u c t e d e m b r y o s c a n i m p l a n t i n t o interspecific uteri, but only three speices have been successfully cloned by iSCNT [14][15][16].…”