Genetic content of the neo-sex chromosomes in ctenonotus and norops (squamata, dactyloidae) and degeneration of the y chromosome as revealed by high-throughput sequencing of individual chromosomes

Artem P. Lisachov, Alexey I. Makunin, Massimo Giovannotti, Jorge C. Pereira, Anna S. Druzhkova, Vincenzo Caputo Barucchi, Malcolm A. Ferguson-Smith, Vladimir A. Trifonov

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Pleurodont lizards are characterized by an ancient system of sex chromosomes. Along with stability of the central component of the system (homologous to the X chromosome of Anolis carolinensis [Dactyloidae], ACAX), in some genera the ancestral sex chromosomes are fused with microautosomes, forming neo-sex chromosomes. The genus Ctenonotus (Dactyloidae) is characterized by multiple X 1 X 1 X 2 X 2 /X 1 X 2 Y sex chromosomes. According to cytogenetic data, the large neo-Y chromosome is formed by fusion of the ancestral Y chromosome with 2 microautosomes (homologous to ACA10 or ACA11 and ACA12), the X 1 chromosome is formed by fusion of the ancestral X chromosome with the autosome homologous to ACA10 or ACA11, and the X 2 chromosome is homologous to autosome ACA12. To determine more precisely the content and evolution of the Ctenonotus sex chromosomes, we sequenced flow-sorted chromosomes (both sex chromosomes and microautosomes as control) of 2 species with a similar system: C. pogus and C. sabanus. Our results indicate that the translocated part of the X 1 is homologous to ACA11, X 2 is homologous to ACA12, and the Y contains segments homologous to both ACA11 and ACA12. Molecular divergence estimates suggest that the ancestral X-derived part has completely degenerated in the Y of Ctenonotus, similar to the degeneration of the Norops sagrei Y chromosome (Dactyloidae). The newly added regions show loss of DNA content, but without degeneration of the conserved regions. We hypothesize that the translocation of autosomal blocks onto sex chromosomes facilitated rapid degeneration of the pseudoautosomal region on the ancestral Y.

Original languageEnglish
Pages (from-to)115-122
Number of pages8
JournalCytogenetic and Genome Research
Volume157
Issue number1-2
DOIs
Publication statusPublished - 1 Apr 2019

Keywords

  • Degeneration
  • Gonosome evolution
  • Lizards
  • Next-generation sequencing
  • Reptile
  • Sex chromosomes
  • KARYOTYPES
  • ORIGIN
  • EVOLUTION
  • TIME
  • GENOME
  • Chromosome Painting/methods
  • Translocation, Genetic
  • Species Specificity
  • Male
  • High-Throughput Nucleotide Sequencing/methods
  • Lizards/classification
  • X Chromosome/genetics
  • Animals
  • DNA/chemistry
  • Female
  • Chromosomes/genetics
  • Y Chromosome/genetics

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