High-Speed Mouse Backcrossing Through the Female Germ Line

Abstract

Transferring mouse mutations into specific mouse strain backgrounds can be critical for appropriate analysis of phenotypic effects of targeted genomic alterations and quantitative trait loci. Speed congenic breeding strategies incorporating marker-assisted selection of progeny with the highest percentage target background as breeders for the next generation can produce congenic strains within approximately 5 generations. When mating selected donor males to target strain females, this may require more than 1 year, with each generation lasting 10 to 11 weeks including 3 weeks of gestation and 7 to 8 weeks until the males reach sexual maturity. Because ovulation can be induced in female mice as early as 3 weeks of age, superovulation-aided backcrossing of marker-selected females could accelerate the production of congenic animals by approximately 4 weeks per generation, reducing time and cost. Using this approach, we transferred a transgenic strain of undefined genetic background to >99% C57BL/6J within 10 months, with most generations lasting 7 weeks. This involved less than 60 mice in total, with 9 to 18 animals per generation. Our data demonstrate that high-speed backcrossing through the female germline is feasible and practical with small mouse numbers.

A new mouse SNP genotyping assay for speed congenics: combining flexibility, affordability, and power

“…We used two to three breeders per generation and performed backcrosses until 99.8% of the congenic strain was achieved in the offspring, following standard congenics practices (e.g. [ 6 , 21 , 22 ],). We chose to genotype all offspring containing the gene of interest at each generation to maximize the effectiveness of the speed congenics approach and thereby minimize the total number of generations required (Table S 3 ) [ 23 ].…”

Sst- and Vip-Cre mouse lines without age-related hearing loss

“…However, CBA and C57 mice have significant genetic and behavioral differences (Lilue et al, 2018;Sultana et al, 2019), rendering F1 C57-CBA crosses heterozygous in many key alleles. Thus, it is desirable to iteratively backcross AHL-negative C57-CBA hybrids onto the CBA background across multiple generations (>F4) to achieve genetic homogeneity suitable for the multi-generational breeding schemes that are often necessary to leverage the power of Cre (Grove et al, 2016;Markel et al, 1997).…”

Aquatic models of human ciliary diseases

“…Additionally, with the advent of whole exome sequencing and the increased accessibility of genome wide association studies, researchers are finding new candidate genes underlying human many diseases. Given that generating mouse lines is both costly and time consuming, other model organisms that do not have these limitations such as Xenopus and zebrafish are being used to identify and study candidate genes (Grove, Eckardt, & John McLaughlin, 2016).…”