Genetic identity of clones and methods to explore DNA.

Cloning by nuclear transfer has made it possible to produce genetically identical animals in terms of nuclear DNA content. Recent molecular biology tools are offering scientific ways to get an insight into the identity issues, by exploring and comparing genomes of cloned animals in order to test their genetic identity and methylation differences. We have initiated a study to compare genomic DNA of bovine adult clones, of normal phenotype. We have used, in parallel, the AFLP technique (amplification fragment length polymorphism) and one of its variant, MSAP (methylation-sensitive amplification polymorphism). We are also investigating other techniques leading to the detection of sequence polymorphisms between two genomes based on genomes hybridisation. We chose the representational difference analysis (RDA) methods that can be combined with mismatch-specific recognition or mismatch binding property of some proteins (CEL I, MutS). We plan to use these RDA methods for genome-wide detection of subtle mutations, then to focus on changes affecting the methylation status of promoting genomic regions in abnormal clones. This will be achieved using MSAP with NotI and applying, in parallel, the RLGS (restriction landmark genome scanning) technique. This study will hopefully improve the molecular and functional characterizations of these "new animals."