Table_S6

Nucleotide sequence divergence (Kz) in intron10 and intron 11 of male-derived CTNNB1Z sequences among eight snake species (below diagonal), and female-derived CTNNB1Z sequences (above diagonal). Standard errors are indicated for all values. Table is also available in PDF format in the "Supplementary file" PD

Table_S3

Frequencies of synonymous and nonsynonymous substitutions in the exon11 of male-derived CTNNB1Z sequences among eight snake species. Ks values are shown above the diagonal, and Ka values are shown below the diagonal. Standard errors are indicated in all values. Table is also available in PDF format in the "Supplementary file" PD

Data from: Evolutionary dynamics of the gametologous CTNNB1 gene on the Z and W chromosomes of snakes

Snakes exhibit genotypic sex determination with female heterogamety (ZZ males and ZW females), and the state of sex chromosome differentiation also varies among lineages. To investigate the evolutionary history of homologous genes located in the non-recombining region of differentiated sex chromosomes in snakes, partial sequences of the gametologous CTNNB1 gene were analyzed for 12 species belonging to henophid (Cylindrophiidae, Xenopeltidae, and Pythonidae) and caenophid snakes (Viperidae, Elapidae, and Colubridae). Nonsynonymous/synonymous substitution ratios (Ka/Ks) in coding sequences were low (Ka/Ks < 1) between CTNNB1Z and CTNNB1W, suggesting that these two genes may have similar functional properties. However, frequencies of intron sequence substitutions and insertion-deletions were higher in CTNNB1Z than CTNNB1W, suggesting that Z-linked sequences evolved faster than W-linked sequences. Molecular phylogeny based on both intron and exon sequences showed the presence of two major clades: (1) Z-linked sequences of Caenophidia, and (2) W-linked sequences of Caenophidia clustered with Z-linked sequences of Henophidia, which suggests that the sequence divergence between CTNNB1Z and CTNNB1W in Caenophidia may have occurred by the cessation of recombination after the split from Henophidia

Karyological characterization and identification of four repetitive element groups (the 18S – 28S rRNA gene, telomeric sequences, microsatellite repeat motifs, Rex retroelements) of the Asian swamp eel (Monopterus albus)

Among teleost fishes, Asian swamp eel (Monopterus albus Zuiew, 1793) possesses the lowest chromosome number, 2n = 24. To characterize the chromosome constitution and investigate the genome organization of repetitive sequences in M. albus, karyotyping and chromosome mapping were performed with the 18S – 28S rRNA gene, telomeric repeats, microsatellite repeat motifs, and Rex retroelements. The 18S – 28S rRNA genes were observed to the pericentromeric region of chromosome 4 at the same position with large propidium iodide and C-positive bands, suggesting that the molecular structure of the pericentromeric regions of chromosome 4 has evolved in a concerted manner with amplification of the 18S – 28S rRNA genes. (TTAGGG)n sequences were found at the telomeric ends of all chromosomes. Eight of 19 microsatellite repeat motifs were dispersedly mapped on different chromosomes suggesting the independent amplification of microsatellite repeat motifs in M. albus. Monopterus albus Rex1 (MALRex1) was observed at interstitial sites of all chromosomes and in the pericentromeric regions of most chromosomes whereas MALRex3 was scattered and localized to all chromosomes and MALRex6 to several chromosomes. This suggests that these retroelements were independently amplified or lost in M. albus. Among MALRexs (MALRex1, MALRex3, and MALRex6), MALRex6 showed higher interspecific sequence divergences from other teleost species in comparison. This suggests that the divergence of Rex6 sequences of M. albus might have occurred a relatively long time ago

Supplementary file

Supplementary file includes supplementary figures and tables, which are relevant to publication. Please note that the supplementary tables included in this PDF are also uploaded separately, as .xlsx files

Snakes in this study

Snake samples (figure/species) used in this study

Table_S5

Frequencies of nonsynonymous/synonymous substitution ratios (Ka/Ks) in exon 11 of the CTNNB1 gene among eight snake species. The CTNNB1W gene is shown above the diagonal with the CTNNB1Z gene below the diagonal. Table is also available in PDF format in the "Supplementary file" PD

Table S1

Species and nucleotides sequences of the CTNNB1 gene used in this study. Table is also available in PDF format in the "Supplementary file" PD

Table_S2

Pair-wise comparison of amino acid sequence identities (%) of CTNNB1W among eight snake species. Table is also available in PDF format in the "Supplementary file" PD