LINE class retroposon is a component of DNA polymorphic fragments of trematode Himasthla elongata parthenitae

Abstract

We found that the S-SAP (Sequence-Specific Amplification Polymorphism) method revealed clonal variability in the genomes of flatworm Himasthla elongata (Trematoda, Echinostomatidae) larvae. The larvae are parthenogenetic and have been considered genetically homogeneous. We performed cloning and sequencing of an about 500-bp conservative fragment (B1). B1 sequence analysis showed that this fragment had maximal homology with LINE elements from the CR1 family of Hydra and sparrow. In situ hybridization (FISH) revealed B1 dispersed distribution. Several other fragments cloned from the same agarose electrophoresis band correspond to the conservative domain of reverse transcriptase (RT) from CR1 family. Thus, it has been shown that (1) cercariae of trematode H. elongata have clonal variability, (2) the S-SAP method allows patterns to be obtained of fragment distribution characteristic for individual cercariae, and (3) RT conservative domain of the CR1 family participates in the pattern of polymorphic fragments generation. Identification of the CR1 transcripts in H. elongata cercariae transcriptom will be the aim of a future work. Cloning of variable fragments from the pattern of fragments is in progress.