Characterisation of arginine kinase intron regions and their potential as molecular markers for population genetic studies of Bithynia snails (Gastropoda: Bithyniidae) in Thailand

Abstract

ABSTRACT Three taxa of Bithynia snails, Bithynia funiculata, B. siamensis siamensis and B. siamensis goniomphalos, are currently recognised in Thailand. They serve as first intermediate hosts for the liver fluke Opisthorchis viverrini sensu lato. This study aims to characterise the arginine kinase gene intron regions (AKInt) for further use as molecular markers to explore the genetic variation and differentiation of Bithynia snails in Thailand. Four intron regions belonging to the AK gene, namely AK intron 1 (AKInt1) to AK intron 4 (AKInt4) were characterised for B. funiculata, B. s. siamensis and B. s. goniomphalos. Of these, AKInt1 showed a high level of genetic variability and was the most appropriate region for reliably examining the genetic variation of Bithynia species/subspecies and discriminating between them. Two different forms of AKInt1, namely AKInt1-long containing a long fragment (∼341–351 bp) and a short fragment (∼213–229 bp), and AKInt1-short containing only a short fragment, were observed. Insertions/deletions (indels) were commonly found within AKInt1 leading to observed heterozygosity. This study revealed that nucleotide polymorphism was high in the long fragment, which was observed in some specimens. The short fragment was common in all samples and can potentially be used to discriminate between Bithynia taxa.