International Mammalian Genome Society

logo18th International Mouse Genome Conference

17-22 October 2004, Seattle, USA


Adams CPA, Castile CAC, Petit DCP, Poirier CP, Bishop CEB

Baylor College of Medicine, Houston, United States

We previously outlined a phenotype driven mutagenesis project in the FVB inbred albino background.  Our concatameric transgenes contained tyrosinase and was flagged by repeats specific for Sleeping Beauty transposases.  Transmission of the transgene was followed with pigmented progeny.  By use of a transposase, single copies of the tandem array of transgenes were excised and pasted else where in the genome. “Jumps” were identified by the appearance of new color patterns indicating new expression patterns/loci of tyrosinase.  New integrations, after being separated from the original transgene, were then brought to the homozygous level and screened for abnormal phenotypes.  Given the high frequency of jumps, a single transgene can theoretically be inserted, excised, then inserted again in the germ line.  Given this possibility, associated phenotypes need to be linked to either the genetic disruption caused by insertion of the transgene at the new locus or from the molecular signature left from the previous integration site.  In the case where the two sites are closely linked, we have developed a method to distinguish which loci is responsible for the phenotype. 

Additionally, we have begun using a linearized version of the transgene which improves upon the original design of the project in two important ways.  Firstly, new colors can be unambiguously identified.  Linearized transgenic founders are albino due to vector regions which inhibit expression of tyrosinase.  New colors seen in progeny are therefore unmistakably induced by the integration of tyrosinase at a new locus.  Secondly, a linearized transgene enhances both the rate and ease of cloning; a significant advantage when original transgene site and new integration site are closely linked.

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