Phylogeny of Sphaerium solidum (Bivalvia) based on karyotype and sequences of 16S and ITS1 rDNA

Abstract

The present work represents the first karyological and molecular characterisation of Sphaerium solidum, a rare European clam. Specimens of S. solidum were collected in Lithuania and Hungary. The modal diploid chromosome number found in both populations was 2n=30. Small, biarmed B chromosomes were found in 42.3% of cells studied in clams from Lithuania and in 11.8% of cells in clams from Hungary. Comparative analysis revealed no significant (P<0.05) interspecific differences in chromosome morphology of S. solidum and that of previously studied S. corneum. DNA sequence analyses of S. solidum showed no interpopulation differences in ITS1; moreover, only one site was different from ITS1 of S. corneum. However, differences in mitochondrial 16S sequence of S. solidum were revealed: two haplotypes in Lithuania and three in Hungary were identified. The genetic characteristics revealed in this study do not support ascription of S. solidum and S. corneum to different subgenus, Cyrenastrum and Sphaerium s. str., respectively. Comparative cytogenetic analysis disclosed that the chromosome morphology could be conserved in some sphaeriid species during speciation despite the fact that most other species in this family undergo radical karyotypic differentiation.

The taxonomic identity and phylogenetic relationships of Cercaria pugnax and C. helvetica XII (Digenea: Lecitho-dendriidae) based on morphological and molecular data

“…Total genomic DNA for molecular analysis was isolated from specimens of C. pugnax and C. helvetica XII according to the protocol by Stunžėnas et al (2011) with a slight modification described in Petkevičiūtė et al (2014). DNA fragments spanning the 3'end of 5.8S rRNA gene, complete internal transcribed spacer 2 region (ITS2) and a few nucleotides at the 5' end of the 28S gene were amplified using forward primer 3S (5'-CGG TGG ATC ACT CGG CTC GTG-3') and reverse primer 28S (5'-CCT GGT TAG TTT CTT TTC CTC CGC-3') (Bowles et al 1995).…”

Phylogenetic relationships of some species of the family Echinostomatidae Odner, 1910 (Trematoda), inferred from nuclear rDNA sequences and karyological analysis

“…In previous study this method allowed us to extract high quality DNA from tissue of molluscs (Stunžėnas et al 2011) and trematodes (Petkevičiūtė et al 2014). An entire nuclear 5.8S-ITS2-28S DNA sequence of ribosomal DNA (~460bps: 5.8S ribosomal RNA gene, partial sequence; internal transcribed spacer 2, complete sequence; and 28S ribosomal RNA gene, partial sequence) was amplified using primers: 3S (5’- CGG TGG ATC ACT CGG CTC GTG -3’), forward direction; 28S (5’- CCT GGT TAG TTT CTT TTC CTC CGC -3’), reverse direction (Bowles et al 1995).…”

Molecular and karyological identification and morphological description of cystocercous cercariae of Phyllodistomum umblae and Phyllodistomum folium (Digenea, Gorgoderidae) developing in European sphaeriid bivalves

“…Total genomic DNA was extracted from trematodes according to the protocol used by Stunžėnas et al [16] for mollusks and modified for helminths [17]. An entire nuclear 5.8-ITS2-28S DNA sequence of ribosomal RNA (~480 bps) and 28S rDNA (~1250 bps) were amplified according to the protocol used in our previous studies [5,17].…”