Genetic contamination in a colony of BALB/cj and the refresh of the colony as a critical point

Abstract

The genetic quality of laboratory animals is essential for the reproducibility of scientific research. There are many genetically defined lines of mice, such as inbred strains and congenic. These lines have important characteristics, such as genetic isogenicity, phenotypic uniformity, which is the axis of the reproducibility of the experiments. The control and preservation of the genetic quality of the laboratory animal should be a priority. The aim of this work was to evaluate the authenticity the of mouse strain BALB/cJ from of colony from an experimental conventional animal care facility of the region and highlight the importance of genetic monitoring and show the consequences of an absence of refresh of the colony periodically. This strain BALB/cJ arrived at this animal care facility ground in the year 2000.Thereafter polygamous mating were made, until 2020.For twenty years a refresh of the colony of animals was not made. It is important to highlight that the periodicity of the colony refresh should be made from F5 to F10 generations, to have an optimal management of the colony. Microsatellite analysis by PCR is one of the most widely used methods in genetic quality controls of inbred lines. Tail samples(3-5mm) were taken from female(N=4), and genomic DNA was obtained by organic extraction. We analyzed 12 microsatellite loci that were located on twelve different autosomal chromosomes and polymorphic. Selected from the information database; www.informatics.jax.org . This panel allows the discrimination of the main strains present in Argentina: BALB/c, C3H/He and DBA/2J, C57BL/6J. The results showed evidence of genetic contamination with the positive control DBA/2J and C3H/HeJ strains; 10 of the 12 microsatellites analyzed were homozygous for the expected alleles and genotypes compatible with the positive control the BALB/cJ strain. On the contrary, the remaining two microsatellites presented the following genotypes: D2Mit493(97pb), compatible alleles for the DBA/2J strain and D12Mit12(164pb), for the C3H/HeJ strain. The results were reported to the experimental conventional animal care facility of the region, and based on this report the entire colony was renewed with new genetically controlled animals. <br /> It is necessary to encourage routine genetic checks, every two years, to ensure that the results obtained are reproducible and have scientific validity and to encourage, technicians and professionals to continue training in the science of laboratory animals. <br /><br />