The modifications include topography changes (smoothening or roughing), formation of micro-cracks, phase transformations, deformation hardening, formation of oxides, formation of solid films by reactions with lubricant additives, transfer of material from the counter surface, and so on.
In the present study, 93% (431/462) embryo transfers belong to "additive gene transfer" and 7% (31/462) embryo transfers belong to "homologous recombination"; there is also no significant difference in PR rate between them.
Most importantly, more live and healthy offspring were obtained when fetal fibroblasts or kidney cells were modified by additive gene transfer and the resulting SCNT embryos were transferred in the winter period.
Interestingly, we could confirm beneficial effects of cloning in winter, using additive gene transfer, and fetal fibroblasts or kidney cells, in an additional analysis (data not shown), where we explicitly targeted the fraction of early neonatal death cases out of live piglets in experiments, which in principle could produce viable offspring (indicated by at least one live piglet).
We further demonstrate that additive gene transfer using lentiviral vectors encoding gp91phox is capable of restoring NADPH-oxidase activity in mature neutrophils derived from X-CGD iPSC.
AGT: additive gene transfer, HR: homologous recombination.
The cells derived from transfection were genetically modified by additive gene transfer (Table 8) or by homologous recombination (Table 9).
HR: homologous recombination, AGT: additive gene transfer, Replication of transgenic pigs: replication of already existing transgenic pig lines.
Hence, different primary kidney cells, including PKCm and PKC2109, were capable of producing genetically modified pigs by additive gene transfer.
Genetic modifications were categorized into three classes: additive gene transfer, homologous recombination, and replication of already existing transgenic pigs.
