The retroviral vector （RCAS） has been widely used in avian system to study development and diseases, but is not suitable for mammals which do not produce the retrovirus receptor TVA. In this review, we trace the current uses of RCAS-TVA approach in mammalian system with improved strategies, including generation of tv-a transgenic mice, use of soluble TVA receptor and retroviral receptor-ligand fusion proteins, improvement of RCAS vectors, and compare a series of mammalian models in variant studies of gene function, development, oncogenesis and gene therapy. All those studies demonstrate that the RCAS-TVA based mammalian models are powerful tools for understanding the mechanisms and target treating of human diseases.
The commercially available inbred obesity-prone C57BL/6J （B6） and outbred stock ICR mice （3-week old） purchased from a breeder of Beijing were weaned onto high-fat diet （HFD）, HFD-3% fructose water （HFDF） and standard rodent chow, respectively. After exposure to the diets for six weeks, HFD and HFDF fed mice were injected intraperitoneally with streptozotocin （STZ, 100mg/kg body weight） and kept on the same diet for next four weeks. Body weight was recorded weekly. Non-fasting blood glucose levels of HFD and HFDF fed mice were measured before and after STZ injections. The body weight of HFD-fed and HFDF-fed B6 mice were significantly lower than that of the control, but body weight of HFD-fed and HFDF-fed ICR mice were significantly higher than that of the control. After injection of STZ, blood glucose levels were above the stardardized criterion （11 mmol/L） for the diabetes mouse model in both HFD and HFDF fed ICR mice, but reverse in B6 mice. The type 2 diabetes model was generated successfully in ICR but not in B6 mice, regardless of whether fructose was supplied. The current results indicated that ICR mouse is still a useful and economical strain for HFD-induced/STZ-treated type 2 diabetes model, and that some variation may occur in the genetic composition among B6 mice bred by different breeders.
The goal of this study was to investigate the genetic stability of the C57BL/6J （B6） inbred mouse strain maintained in different breeders. Three populations of B6, Popl and Pop2 purchased from Beijing and Pop3 purchased from Shanghai, were examined. Fifteen microsatellite loci reported to be polymorphic among inbred strains were amplified using FAM labeled primers and genotyped with ABI Prism 377 automated sequencer. Seven loci were found polymorphic, and all the loci were homozygous in all the three populations. The present study indicates that genetic variation occurs in different B6 populations although they are still inbred in each breeder. The mechanism of genetic variation is not well understood now, but it is very important to know the precise content of the B6 genome before use of this strain in research.
