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Rapid zygosity determination in mice by SYBR Green real-time genomic PCR of a crude DNA solution

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We examined whether crude DNA extracts prepared from gene-engineered mouse tissues are suitable as a template for zygosity determination by SYBR Green real-time genomic PCR. A crude DNA solution was prepared by brief incubation with lysis buffer containing ear, tail, or fetus of ROSA26 mouse, a gene-trapped strain carrying the β-galactosidase (β-gal) gene. Five serially diluted crude DNA samples (original, 2-, 4-, 8-, 16-diluted) were next prepared and then subjected to three-step (95°C, 60°C and 72°C) reactions of real-time PCR to detect the β-gal gene and the receptor-activity-modifying protein 3 (ramp3) gene (as an internal reference gene). The slopes of standard curves obtained from the real-time PCR indicated that amplification efficiency was approximately 99%, and the efficiencies of target and reference were almost equal. With this system, we next determined the zygosity of mice derived from mating heterozygous ROSA26 females and males, and found a sharp distinction in zygosity, wild-type, heterozygous and homozygous. Assessment of crude DNA samples from other gene-engineered mice including B6ZP3Cre-Tg, B6rAM-Tg, and Ramp2-gene-targeted strains revealed that our method was effective for determination of zygosity. The present method is more convenient and rapid than formerly published methods employing purified genomic DNA as a template. Our method will be particularly useful for experiments requiring rapid and accurate genotyping of gene-modified animals/fetuses.

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This study was supported by a grant from the Ministry of Education, Science, Sports, and Culture, Japan (T. Sakurai).

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Correspondence to Takayuki Sakurai.

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Sakurai, T., Kamiyoshi, A., Watanabe, S. et al. Rapid zygosity determination in mice by SYBR Green real-time genomic PCR of a crude DNA solution. Transgenic Res 17, 149–155 (2008). https://doi.org/10.1007/s11248-007-9134-7

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  • Crude DNA solution
  • Real-time PCR
  • SYBR Green
  • Zygosity
  • Transgenic mice
  • Gene-targeted mice