The Bov-B lines found in Vipera ammodytes toxic PLA(2) genes are widespread in snake genomes

摘要

In the fourth intron of two toxic Vipera ammodytes PLA(2) genes a Ruminantia specific 5'-truncated Bov-B LINE element was identified. Southern blot analysis of Bov-B LINE distribution in vertebrates shows that, apart from the Ruminantia, it is limited to Viperidae snakes (V. ammodytes, Vipera palaestinae, Echis coloratus, Bothrops alternatus, Trimeresurus flavoviridis and Trimeresurus gramineus). The copy number of the 3' end of Bov-B LINE in the V. ammodytes genome is between 62 000 and 75 000. At orthologous positions in other snake PLA(2) genes the Bov-B LINE element is absent, indicating that its retrotransposition in the V. ammodytes PLA(2) gene locus has occurred quite recently, about 5 Myr ago. The amplification of Bov-B LINEs in snakes may have occurred before the divergence of the Viperinae and Crotalinae subfamilies. Due to its wide distribution in Viperidae snakes it should be a valuable phylogenetic marker. The neighbour-joining phylogenetic tree shows two clusters of truncated Bov-B LINE, a Bovidae and a snake cluster, indicating an early horizontal transfer of this transposable element. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 28]