Microsatellite DNA Polymorphisms in Inbred Strain Mice and Selection as Genetic Monitoring Markers

The aim of genetic monitoring is to checking the genetic contamination within inbred starains,which insures that the strains according with the require of colony . At present the methods based on allozyme biochemistry are the National Standard instructed. methods that using microsatellite DNA would be more useful for genetic monitoring than methods based on allozyme biochemistry because the genome itself is being tested rather than a protein product and a larger portion of the genome can be sampled, and easy to distinguish. methods that using microsatellite DNA had abundant microsatellite loci(over 7300,before 1999) can be identified. Applying enough microsatellite loci will present abundant straps and well polymorphism, which can reflection inherit and variation of roundly genene.In addition, this novel approach allows the rapid, sensitive,convenientand accuracy, even individual identificaton. So we should select microsatellite DNA which is polymorphisms as genetic monitoring markers to determining the strains'origin and genetic background of inbred mice. Untill now Only feasibility has been reported,and in which microsatellite DNA loci have not enough polymorphisms to distinguish genetic differences.Articles on standards and practicality have not been founded in our country. With the optimization of components of reaction buffer and amplificaton parameter,PCR for amplification microsatellite DNA was finally set up.Using the techniques microsatellite DNA can amplified efficaciously. The final concentrations of Mg 2+ was 1 .5—3.0 mmol/L,annealing temperature was 50℃—65℃.The condition for the PCR amplify were ,94℃for 3min,30cycles of 94℃ for 30s, 50℃—65℃ for 30s,72℃ for 1min,finally at 72℃ for 1min,then store at 4℃. Ten kinds of inbred strain mice including C57BL/6J,C3H/He, TA1,TA 2,615,BALB/c ,DBA/2N,129/Sv,FVB/N,AMMS/1 were investigated by PCR analysis. 14 microsatellites DNA loci on different chromosomes which we selected applied in genetic monitoring is the first time on 10 commonly used inbred mouse strains. It showed that all these microsatellites DNA loci display single allelic gene band. Fourteen loci are polymorphisms, among which the polymorphisms of D1Mit365、D2Mit30、D3Mit51、D5Mit48、D6Mit102、D10Mit180、D11Mit128、D12Mit147、D14Mit102 and D17Mit36 are significant .These results suggest that these mice tested meet the request of inbred strain. The genetic background of TA1 was similar with that of TA 2,the similarity indices were from 14.3%( C57 between 129)to 92.9%( TA1 between TA 2).This means that TA1 and TA 2 had closer genetic relationship, C57 and 129 had farther relationship. In addition , the similarity indices of BALB/c and BALB/c-nu-nu was 92.9%,All show that strains or substrains can be distinguished by microsatellites DNA. Screened loci showing marked polymorphisms typically reflect the speciality of strains and genetic backgrounds, which could be used in determining the strains' origin and genetic background of mice.