Genotyping Rodents
Suggested methods for obtaining tissue samples for genotyping include:
- tissue obtained from ear punching or ear notching which also serves as a method of identification
- hair bulb samples
- oral swab
- small quantities of blood from distal veins
- tail snips
Procedures to be followed if tail-snipping is performed:
- Tail snipping should be done prior to 21 days of age. Prompt analysis allows identification of the desired genotype prior to weaning.
- In young mice (<21 days of age) where less than 5 mm of tissue is removed anesthesia is not required. Investigators are encouraged however to apply local anesthesia to the tail (i.e. immersion of tail in cold ethanol, application of ethyl chloride spray, lidocaine ointment, etc.)
- Sampling must be performed using a sharp, sterile scalpel blade or scissor. Hemostasis must be accomplished by use of topical coagulants, digital compression, or cautery. Instruments must be disinfected between animals and sharpened regularly to ensure minimization of tissue injury.
- Anesthesia is required in the following instances: a) after 21 days of age, or b) if removing more than 5 mm of the tail tip.
References:
Couse, J.F., Davis, V.L., Tally, W.C. and Korach, K.S. An Improved Method of Genomic DNA Extraction for Screening Transgenic Mice. National Institute of Environmental Health Sciences, National Institutes of Health. BioTechniques 17: 1030-1032, 1994.
Dennis, M.B. IACUC Review of Genetic Engineering. Lab Animal 29(3): 34-37, 2000.
Hofstetter, J.R., Zhang, A., Mayeda, A.R., Guscar, T., Numberger, J.I. and Lahiri D.K. Genomic DNA from Mice: A Comparison of Recovery Methods and Tissue Sources. Biochem Mol Med 62(2): 197-202, 1997.
Irwin, M.H., Moffatt, R.J. and Pinkert, C.A. Identification of Transgenic Mice by PCR Analysis of Salivia. Nat Biotechnol 14(9): 1146-1148, 1996.
Malumbres, M., Mangues, R., Ferrer, N., Lu, S. and Pellicer, A. Isolation of High Molecular Weight DNA for Reliable Genotyping of Transgenic Mice. BioTechniques 22(6): 1114-1119, 1997.
Schmitteckert, E.M., Prokop, C.M. and Hedrich, H.J. DNA Detection in Hair of Transgenic Mice – A Simple Technique Minimizing the Distress on the Animals. Laboratory Animals 33(4): 385-389, 1999.
