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Molecular evolution of CTNNB1 and WAC gametologous genes reveal independent strata of sex chromosomes in caenophidian snakes under a short time period

Session Information

Caenophidian snakes exhibit ZZ/ZW type genetic sex determination with female heterogamety (ZW). The W chromosomes are highly degenerated showing interspecific size variation, centromere position, and amount of heterochromatin. Comparison of the structures and functions of Z and W homologous genes (gametologous genes) is, therefore, important to understand the process of sex chromosome differentiation in caenophidian snakes. Here, partial sequences of two gametologous genes (CTNNB1 and WAC) from 24 caenophidian snakes were analyzed and the state of mutation was compared with nuclear autosomal and mitochondrial genes. Results indicated that the WACW gene had greater size variation resulting from insertions-deletions (indels) than the CTNNB1W gene in the caenophidian lineage. Average Ka/Ks in the coding region of both genes was very low (1), suggesting these gametologous genes presentednegative selection. Molecular phylogenetic plac       ement showed caenophidian snake CTNNB1Z genes clustered together, while caenophidian snake CTNNB1W genes were grouped with henophidian snake CTNNB1 genes. Similar results were found in most WACZ and WACW genes, except for WACW and WACZ genes of Achrochordus javanicus (Elephant trunk snake) grouped in the same clade of each species. This result differed, with a phylogenetic relationship based on nuclear autosomal and mitochondrial genes, suggesting that evolutionary strata occurred independently at the WAC gene located on the long arm of ZW chromosomes in caenophidian snakes.

Jul 05, 2018 11:15 AM - 11:30 AM(UTC)
Venue : 2B9 - Building 2
20180705T1115 20180705T1130 UTC Molecular evolution of CTNNB1 and WAC gametologous genes reveal independent strata of sex chromosomes in caenophidian snakes under a short time period

Caenophidian snakes exhibit ZZ/ZW type genetic sex determination with female heterogamety (ZW). The W chromosomes are highly degenerated showing interspecific size variation, centromere position, and amount of heterochromatin. Comparison of the structures and functions of Z and W homologous genes (gametologous genes) is, therefore, important to understand the process of sex chromosome differentiation in caenophidian snakes. Here, partial sequences of two gametologous genes (CTNNB1 and WAC) from 24 caenophidian snakes were analyzed and the state of mutation was compared with nuclear autosomal and mitochondrial genes. Results indicated that the WACW gene had greater size variation resulting from insertions-deletions (indels) than the CTNNB1W gene in the caenophidian lineage. Average Ka/Ks in the coding region of both genes was very low (1), suggesting these gametologous genes presentednegative selection. Molecular phylogenetic plac       ement showed caenophidian snake CTNNB1Z genes clustered together, while caenophidian snake CTNNB1W genes were grouped with henophidian snake CTNNB1 genes. Similar results were found in most WACZ and WACW genes, except for WACW and WACZ genes of Achrochordus javanicus (Elephant trunk snake) grouped in the same clade of each species. This result differed, with a phylogenetic relationship based on nuclear autosomal and mitochondrial genes, suggesting that evolutionary strata occurred independently at the WAC gene located on the long arm of ZW chromosomes in caenophidian snakes.

2B9 - Building 2 GSA2018_APCC6 GSACC62018@canberra.edu.au
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