Identification of sex specific DNA regions in the snake genome using a subtractive hybridisation technique

Karyotypic studies have shown that a ZZ/ZW sex chromosome system is used by snakes, which chromosomally resembles the ZZ/ZW system used by birds. However genetic studies have shown that SOX 3; the sex determining gene in mammals and DMRT1; which is the hypothesised sex determining gene in birds, are both located on autosomal chromosomes in the snake. Therefore it has been suggested that the snake sex chromosome system is unique and has evolved independently of the bird?s system. This paper describes a subtractive hybridization method, using physical separation of biotinylated 'driver' DNA. The novel application of this technique was its use in identifying sex specific DNA regions within the genome of the Australian python; Morelia spilota imbricate. Female DNA enrichment was achieved using this technique and resulted in the identification of two non-sex specific repeating elements. The conclusion from this work is the identification of female specific DNA in snakes requires further subtractive hybridization enrichment and a more efficient screening procedure.