DNA Fingerprinting In Genetic Monitoring Of Production Expansion Colony Of Inbred Strain Mice

The inbred strain mice which have genetic stability and phenotypic consistency are widely used for scientific studies. These mice are prone to genetic contamination or mutation during the reproduction. Experiment of using the contaminated animal stocks results in financial loss as well as wrong results. So it is very necessary to monitor the genetic quality of inbred strains. For a long time, the traditional methods in genetic monitoring of inbred strains include skin grifting test, coat color test and biochemical marker analysis, etc. DNA fingerprinting has been used for genetic monitoring of inbred strain mice with the development of molecular technology. The objective of this study is to evaluate DNA fingerprinting and the traditional biochemical marker method in genetic monitoring of the production expansion of inbred strain mice. Therefore, we can obtain a more exact, reliable and specific way of genetic monitoring for laboratory animals and build a basis for the standard and the molecular biology method which can be used in genetic monitoring of laboratory animals.DNA fingerprinting of BALB/c, C57BL/6J and DBA/2 inbred strain species mice was performed with the biotin-labeled (GGAT)4 oligonucleotide probe. It showed that more than 10 bands above 2.2-9.4Kb were clearly identified in DNA fingerprints. Meanwhile, the mice of the same strain had the identical fingerprints and the similarity coefficient was 0.95-1.0. Whereas the fingerprints had the great difference of the different strains and the similarity coefficient was 0.21-0.35. These results show that the (GGAT)4 oligonucleotide probe has a good polymorphism and can be used in fingerprinting for genetic monitoring of inbred strain mice.It is believed that there exits genetic contamination if the inbred strain mice are expanded to the fifth generation. Therefore, DNA fingerprinting was performed to monitor the genetic quality of the fourth and fifth generation of the production expansion colony of BALB/c, C57BL/6J and DBA/2 inbred strain mice in Laboratory Animal Center in Lanzhou University. The fingerprints of the fourth generation were basically identical and similarity coefficient was 0.92-1.00. However, the fingerprints of the fifth generation were dissimilar and similarity coefficient was 0.67-0.79. This suggests that there is genetic contamination in the fifth generatin of the inbred strain mice.Biochemical marker is also widely used for genetic monitoring of inbred strain mice according to national standard. DNA fingerprinting of these inbred strains was further compared simultaneously with the traditional method, biochemical marker. Measurement of 13 biochemical markers gene loci (Car-2, Es-1, Es-3, Gpi1, Hbb, Idh-1, Trf, Ce-2, Es-10, Mod-1, Pgm-1, Gpd-1 and Akp-1) was performed by electrophoresis and the results revealed that all observed gene loci were homogenous without any polymorphism and mutation in the fourth generation of three inbred strain mice. Of the 13 loci observed, 0, 1 (Idh-1) and 3 (Idh-1, Es-3 and Es-1) were found to show mutation in the fifth generation of BALB/c, C57BL/6J and DBA/2 inbred strain mice, respectively. DNA fingerprinting was compared with biochemical marker, it was found that there was not any alteration in all strains using analysis of biochemical marker when the patterns in DNA fingerprinting were dissimilar. While the inconsistent results were shown by biochemical marker according to national standard, significant difference could also be detected in the DNA fingerprinting. This suggests DNA fingerprinting is more sensitive than biochemical marker analysis.Blood samples of the production expansion colony of BALB/c, C57BL/6J and DBA/2 inbred strain mice were analyzed. It showed that the every index of blood samples from the first to fourth generation was normal and that from the fifth generation was also in the normal range although the genetic mutation or contamination was detected in the genetic monitoring.In conclusion, these results show that DNA fingerprinting has an advantage in genetic monitoring of inbred strain mice and (GGAT)4 oligonucleotide probe has the high polymorphism. DNA fingerprinting with the biotin-labeled (GGAT)4 oligonucleotide probe can be used to genetic monitoring of BALB/c, C57BL/6J and DBA/2 inbred strain mice.