TY - JOUR

T1 - Heteromorphism of "homomorphic" sex chromosomes in two anole species (Squamata, Dactyloidae) revealed by synaptonemal complex analysis

AU - Lisachov, Artem P.

AU - Trifonov, Vladimir A.

AU - Giovannotti, Massimo

AU - Ferguson-Smith, Malcolm A.

AU - Borodin, Pavel M.

N1 - Publisher Copyright: © 2017 S. Karger AG, Basel.

PY - 2017/6

Y1 - 2017/6

N2 - Iguanians (Pleurodonta) are one of the reptile lineages that, like birds and mammals, have sex chromosomes of ancient origin. In most iguanians these are microchromosomes, making a distinction between the X and Y as well as between homeologous sex chromosomes in other species difficult. Meiotic chromosome analysis may be used to elucidate their differentiation, because meiotic prophase chromosomes are longer and less condensed than metaphase chromosomes, and the homologues are paired with each other, revealing minor heteromorphisms. Using electron and fluorescent microscopy of surface spread synaptonemal complexes (SCs) and immunolocalization of the proteins of the SC (SYCP3), the centromere, and recombination nodules (MLH1), we examined sex chromosome synapsis and recombination in 2 species of anoles (Dactyloidae), Anolis carolinensis and Deiroptyx coelestinus, in which the sex chromosomes represent the ancestral condition of iguanians. We detected clear differences in size between the anole X and Y microchromosomes and found an interspecies difference in the localization of the pseudoautosomal region. Our results show that the apparent homomorphy of certain reptile sex chromosome systems can hide a cryptic differentiation, which potentially may influence the evolution of sexual dimorphism and speciation.

AB - Iguanians (Pleurodonta) are one of the reptile lineages that, like birds and mammals, have sex chromosomes of ancient origin. In most iguanians these are microchromosomes, making a distinction between the X and Y as well as between homeologous sex chromosomes in other species difficult. Meiotic chromosome analysis may be used to elucidate their differentiation, because meiotic prophase chromosomes are longer and less condensed than metaphase chromosomes, and the homologues are paired with each other, revealing minor heteromorphisms. Using electron and fluorescent microscopy of surface spread synaptonemal complexes (SCs) and immunolocalization of the proteins of the SC (SYCP3), the centromere, and recombination nodules (MLH1), we examined sex chromosome synapsis and recombination in 2 species of anoles (Dactyloidae), Anolis carolinensis and Deiroptyx coelestinus, in which the sex chromosomes represent the ancestral condition of iguanians. We detected clear differences in size between the anole X and Y microchromosomes and found an interspecies difference in the localization of the pseudoautosomal region. Our results show that the apparent homomorphy of certain reptile sex chromosome systems can hide a cryptic differentiation, which potentially may influence the evolution of sexual dimorphism and speciation.

KW - Anolis

KW - Deiroptyx

KW - Meiosis

KW - Recombination

KW - Reptilia

KW - Synaptonemal complex

KW - Lizards/genetics

KW - Synaptonemal Complex/genetics

KW - In Situ Hybridization, Fluorescence

KW - Male

KW - Chromosomal Proteins, Non-Histone/genetics

KW - Sex Characteristics

KW - Sex Chromosomes

KW - Animals

KW - Recombination, Genetic

KW - Karyotype

KW - Microscopy, Fluorescence

KW - EVOLUTIONARY DYNAMICS

KW - LACERTA-AGILIS

KW - PATTERN

KW - CHICKEN

KW - DIVERGENCE

KW - MAMMALS

KW - RECOMBINATION

KW - SAND LIZARD

KW - GENOME

KW - GREEN ANOLE

UR - http://www.scopus.com/inward/record.url?scp=85015835529&partnerID=8YFLogxK

U2 - 10.1159/000460829

DO - 10.1159/000460829

M3 - Article

C2 - 28315859

AN - SCOPUS:85015835529

VL - 151

SP - 89

EP - 95

JO - Cytogenetic and Genome Research

JF - Cytogenetic and Genome Research

SN - 1424-8581

IS - 2

ER -