ANAT2341 Lab 5 2013: Difference between revisions
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=Understanding Mechanisms Using Mouse Models= | =Understanding Mechanisms Using Mouse Models= | ||
This | ==Genetic Background== | ||
One of the major advantages of using mouse models is that they are generally made on an inbred genetic background. This means that all mice are genetically identical except for the genetic modification that is under study. These are referred to as '''congenic mouse lines'''. This lack of genetic variability limits the background variance and allows phenotypic changes to be attributed directly to genotype. The most common mouse line in use is called '''C57BL/6''' | |||
==The test of survival - Mendelian ratios== | |||
Some genetic modifications may threaten the survival of mice during development or cause pre-weaning death due a "failure to thrive". | |||
The average litter size for the C57BL/6 strain is approximately 6 | |||
After a few litters it may become apparent that the expected Mendelian ratios are not being met. This can be tested statistically using the Chi Square test. | |||
For example: | |||
A mouse that is hemizygous for a transgene insertion crossed with a wild type mouse would be expected to produce 50% hemizygous transgenic offspring and 50% wild type offspring. | |||
A mouse that has a heterozygous deletion in an endogenous gene crossed with another heterozygous mutant would be expected to produce wild types: heterozygotes amd homozygous mutants at a ratio of 1:2:1 | |||
Revision as of 17:11, 25 July 2013
Understanding Mechanisms Using Mouse Models
Genetic Background
One of the major advantages of using mouse models is that they are generally made on an inbred genetic background. This means that all mice are genetically identical except for the genetic modification that is under study. These are referred to as congenic mouse lines. This lack of genetic variability limits the background variance and allows phenotypic changes to be attributed directly to genotype. The most common mouse line in use is called C57BL/6
The test of survival - Mendelian ratios
Some genetic modifications may threaten the survival of mice during development or cause pre-weaning death due a "failure to thrive". The average litter size for the C57BL/6 strain is approximately 6 After a few litters it may become apparent that the expected Mendelian ratios are not being met. This can be tested statistically using the Chi Square test.
For example:
A mouse that is hemizygous for a transgene insertion crossed with a wild type mouse would be expected to produce 50% hemizygous transgenic offspring and 50% wild type offspring.
A mouse that has a heterozygous deletion in an endogenous gene crossed with another heterozygous mutant would be expected to produce wild types: heterozygotes amd homozygous mutants at a ratio of 1:2:1
