By sequencing the genomes and the transcriptomes of the venom gland, accessory gland and a multi-tissue archive of two species of snake (king cobra and the Burmese python), followed by extensive evolutionary analysis of the toxin sequences, we have been able to confirm for the first time a previously proposed but poorly documented hypothesis about the origin and evolution of snake venom genes.
By (i) gene duplication and (ii) gene hijacking of ‘physiologically normal’ non-toxic proteins expressed in non-venom gland tissues such as stomach, spleen, liver, blood, testes, and ovaries (PNAS 2013 and PNAS 2013).