The genetically modified males were then bred with normal females to produce large litters.
The resulting chimeras are then bred and the offspring examined to see if all of their cells are progeny of the inserted cells.
These stallions were then bred to ranch horses in Nebraska and Colorado, and in the early 1900s the two stallions who every registered Colorado Ranger traces to, Patches #1 and Max #2, were foaled.
The initial crosses were made between Gotland and Icelandic mares (who visually closely resembled the tarpan, especially in the shape of the head) and Przewalski's horse stallions (who provided the desired dun coloration and upright mane), and the offspring were then bred to each other.
The identified Ing2+/− mice were then bred with C57BL/6J mice to segregate the EIIa-Cre transgene.
Positive ES cell clones were selected for injection into blastocysts to produce chimeric mice that were then bred to C57BL/6 to obtain germ line transmission.
ES cells were microinjected into mouse blastocysts to generate chimeras, which were then bred to produce heterozygotes with Tnnt2 ablation (Tnnt2+/−).
For these studies, ApcMin/+ mice were crossed with Faslpr mice to generate ApcMin/+/Faslpr/+ mice, which were then bred to generate ApcMin/+/Faslpr mice.
Male and female chimaeric offspring, identified by the presence of agouti coat colour, were then bred to C57BL/6J mice to assay for germ-line transmission.
To generate Sirt1−/− embryos for primitive spermatogenic stem cell analysis, Sirt1+/− mice were bred with Oct4-GFP mice and then backcrossed to generate Sirt1+/− mice that were homozygous for the Oct4-GFP transgene, which were then bred together.
Correctly targeted ES cell lines, as confirmed by PCR and Southern blotting, were injected into blastocysts to generate chimeric mice, which were then bred to obtain germline transmission of the targeted I-Aβ locus.
