The previous study of Smad3 gene knockout mice ( Smad3 ex8/ex8 )shows that the Smad3 ex8/ex8 mice develop progressive leukocytosis, periodontitis, gastritis, colitis and chronic infection with abscess formation adjacent to mucosal surfaces .symptomatic mutant mice exhibit thymic involution, enlarged lymph nodes and T cells with activated phenotype. Further study suggests that the thymic cells and peripheral T ceels of Smad3 ex8/ex8 mice have lost the response to TGF β.Furthermore, nwe found that the homologous Smad3 ex8/ex mice developed degenerative joint disease resembling human osteoarthritis, osteoporosis and wound healing up quicker. So the mice can serve as an ideal animal model for immune dysregulation, osteoarthritis and so on. To futher study the important role of Smad3 during the vertebrate development ,we charactered the genotype and reproduce the Smad3 knockout mice .Compare to the general experimental mice, the mice of genetic modifications is different in the breeding and reproduction. Besider the reproduction of inbred lines, we also must keep the mice inherit the mutant gene and consider the influence of mutant gene to the mouse’s reproduction. Using PCR and Southern blot to characterize the genotype of the offspring can solve the question .Just like the homozygote of Smad3 ex8/ex8 mice lacking fertility, the homozygous mice cann’t be used for propagating. We use the heterozygous mice for propagating, while the homozygous and wild type mice were used for phenotype analysis. The Smad3 ex8/ex8 heterzyous mice were used for breeding. With genotype being characterized, we found that the ratio of 3 genotype of the Smad3 ex8/ex8 heterzyous mice’ offsprings fits the Mendel’s laws. Their gestation is the sames as others mice,and embryo interval and litter are not different from others, We kept means of cryopreservation by vitrification of embryos and got normal conditions .Using the Smad3 ex8/ex8 heterzyous mice for propagating, we can be used for keeping breed and propagating.
