An Analysis of IS630/Tc1/mariner Transposons in the Genome of a Pacific Oyster, Crassostrea gigas

Transposable elements represent the DNA fragments capable of increasing their copy number and moving within the genome. Class II mobile elements represents the DNA transposons, which transpose via excision and the subsequent reinsertion at random genomic loci. The increase of their copy number occurs only when the transposition event is coupled with the replication. IS630/Tc1/mariner DNA transposon superfamily is one of the largest and widely distributed among the Class II elements. In this work, we provide a detailed analysis of IS630/Tc1/mariner DNA transposons from the Pacific oyster, Crassostrea gigas. IS630/Tc1/mariner transposons represented in the genome of the Pacific oyster belong to four families, Tc1 (DD34E), mariner (DD34D), pogo (DDxD), and rosa (DD41D). More than a half of IS630/Tc1/mariner elements from C. gigas belong to Tc1 family. Furthermore, Mariner-31_CGi element was shown to represent a new and previously unknown family with DD37E signature. We also discovered the full-size transcripts of eight elements from Tc1, mariner, and pogo families, three of which can, presumably, retain their transposition activity.