scholarly journals Snake W Sex Chromosome: The Shadow of Ancestral Amniote Super-Sex Chromosome

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2386
Author(s):  
Worapong Singchat ◽  
Syed Farhan Ahmad ◽  
Nararat Laopichienpong ◽  
Aorarat Suntronpong ◽  
Thitipong Panthum ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosome Analysis ◽  
Chromosome Conformation ◽  
Principal Mechanism ◽  
Squamate Reptiles ◽  
Genomic Landscape ◽  
Heteromorphic Sex Chromosomes

Heteromorphic sex chromosomes, particularly the ZZ/ZW sex chromosome system of birds and some reptiles, undergo evolutionary dynamics distinct from those of autosomes. The W sex chromosome is a unique karyological member of this heteromorphic pair, which has been extensively studied in snakes to explore the origin, evolution, and genetic diversity of amniote sex chromosomes. The snake W sex chromosome offers a fascinating model system to elucidate ancestral trajectories that have resulted in genetic divergence of amniote sex chromosomes. Although the principal mechanism driving evolution of the amniote sex chromosome remains obscure, an emerging hypothesis, supported by studies of W sex chromosomes of squamate reptiles and snakes, suggests that sex chromosomes share varied genomic blocks across several amniote lineages. This implies the possible split of an ancestral super-sex chromosome via chromosomal rearrangements. We review the major findings pertaining to sex chromosomal profiles in amniotes and discuss the evolution of an ancestral super-sex chromosome by collating recent evidence sourced mainly from the snake W sex chromosome analysis. We highlight the role of repeat-mediated sex chromosome conformation and present a genomic landscape of snake Z and W chromosomes, which reveals the relative abundance of major repeats, and identifies the expansion of certain transposable elements. The latest revolution in chromosomics, i.e., complete telomere-to-telomere assembly, offers mechanistic insights into the evolutionary origin of sex chromosomes.

scholarly journals First Report of Sex Chromosomes in Night Lizards (Scincoidea: Xantusiidae)

2020 ◽  
Vol 111 (3) ◽  
pp. 307-313 ◽  
Author(s):  
Stuart V Nielsen ◽  
Brendan J Pinto ◽  
Irán Andira Guzmán-Méndez ◽  
Tony Gamble
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Restriction Site ◽  
Sex Chromosome ◽  
Chromosome 2 ◽  
Squamate Reptiles ◽  
Determining Modes ◽  
Heteromorphic Sex Chromosomes ◽  
Sex Chromosome System ◽  
Cytogenetic Methods

Abstract Squamate reptiles (lizards, snakes, and amphibians) are an outstanding group for studying sex chromosome evolution—they are old, speciose, geographically widespread, and exhibit myriad sex-determining modes. Yet, the vast majority of squamate species lack heteromorphic sex chromosomes. Cataloging the sex chromosome systems of species lacking easily identifiable, heteromorphic sex chromosomes, therefore, is essential before we are to fully understand the evolution of vertebrate sex chromosomes. Here, we use restriction site-associated DNA sequencing (RADseq) to classify the sex chromosome system of the granite night lizard, Xantusia henshawi. RADseq is an effective alternative to traditional cytogenetic methods for determining a species’ sex chromosome system (i.e., XX/XY or ZZ/ZW), particularly in taxa with non-differentiated sex chromosomes. Although many xantusiid lineages have been karyotyped, none possess heteromorphic sex chromosomes. We identified a ZZ/ZW sex chromosome system in X. henshawi—the first such data for this family. Furthermore, we report that the X. henshawi sex chromosome contains fragments of genes found on Gallus gallus chromosomes 7, 12, and 18 (which are homologous to Anolis carolinensis chromosome 2), the first vertebrate sex chromosomes to utilize this linkage group.

scholarly journals The Diversity and Evolution of Sex Chromosomes in Frogs

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 483
Author(s):  
Wen-Juan Ma ◽  
Paris Veltsos
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Ancestral State ◽  
Heteromorphic Sex Chromosomes ◽  
Genomic Studies ◽  
Evolutionary Trajectories ◽  
Heterogametic Sex

Frogs are ideal organisms for studying sex chromosome evolution because of their diversity in sex chromosome differentiation and sex-determination systems. We review 222 anuran frogs, spanning ~220 Myr of divergence, with characterized sex chromosomes, and discuss their evolution, phylogenetic distribution and transitions between homomorphic and heteromorphic states, as well as between sex-determination systems. Most (~75%) anurans have homomorphic sex chromosomes, with XY systems being three times more common than ZW systems. Most remaining anurans (~25%) have heteromorphic sex chromosomes, with XY and ZW systems almost equally represented. There are Y-autosome fusions in 11 species, and no W-/Z-/X-autosome fusions are known. The phylogeny represents at least 19 transitions between sex-determination systems and at least 16 cases of independent evolution of heteromorphic sex chromosomes from homomorphy, the likely ancestral state. Five lineages mostly have heteromorphic sex chromosomes, which might have evolved due to demographic and sexual selection attributes of those lineages. Males do not recombine over most of their genome, regardless of which is the heterogametic sex. Nevertheless, telomere-restricted recombination between ZW chromosomes has evolved at least once. More comparative genomic studies are needed to understand the evolutionary trajectories of sex chromosomes among frog lineages, especially in the ZW systems.

Heteromorphic Sex Chromosomes and Their DNA Content in Fish: An Insight through Satellite DNA Accumulation in Megaleporinus elongatus

2020 ◽  
Vol 160 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Carolina Crepaldi ◽  
Patricia P. Parise-Maltempi
Keyword(s):  
Sex Chromosomes ◽  
Dna Content ◽  
Satellite Dna ◽  
Sex Chromosome ◽  
Neotropical Fish ◽  
High Throughput Analysis ◽  
Multiple Sex Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Sex Chromosome System ◽  
Graph Based Clustering

The repetitive DNA content of fish sex chromosomes provides valuable insights into specificities and patterns of their genetic sex determination systems. In this study, we revealed the genomic satellite DNA (satDNA) content of Megaleporinuselongatus, a Neotropical fish species with Z1Z1Z2Z2/Z1W1Z2W2 multiple sex chromosomes, through high-throughput analysis and graph-based clustering, isolating 68 satDNA families. By physically mapping these sequences in female metaphases, we discovered 15 of the most abundant satDNAs clustered in its chromosomes, 9 of which were found exclusively in the highly heterochromatic W1. This heteromorphic sex chromosome showed the highest amount of satDNA accumulations in this species. The second most abundant family, MelSat02-26, shared FISH signals with the NOR-bearing pair in similar patterns and is linked to the multiple sex chromosome system. Our results demonstrate the diverse satDNA content in M. elongatus, especially in its heteromorphic sex chromosome. Additionally, we highlighted the different accumulation patterns and distribution of these sequences across species by physically mapping these satDNAs in other Anostomidae, Megaleporinusmacrocephalus and Leporinusfriderici (a species without differentiated sex chromosomes).

scholarly journals Evolutionary Dynamics of Sex Chromosomes of Paleognathous Birds

2019 ◽  
Vol 11 (8) ◽  
pp. 2376-2390 ◽  
Author(s):  
Luohao Xu ◽  
Simon Yung Wa Sin ◽  
Phil Grayson ◽  
Scott V Edwards ◽  
Timothy B Sackton
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Recombination Suppression ◽  
Evolutionary Forces ◽  
Genomic Level ◽  
Standard Models ◽  
Pseudoautosomal Regions

Abstract Standard models of sex chromosome evolution propose that recombination suppression leads to the degeneration of the heterogametic chromosome, as is seen for the Y chromosome in mammals and the W chromosome in most birds. Unlike other birds, paleognaths (ratites and tinamous) possess large nondegenerate regions on their sex chromosomes (PARs or pseudoautosomal regions). It remains unclear why these large PARs are retained over >100 Myr, and how this retention impacts the evolution of sex chromosomes within this system. To address this puzzle, we analyzed Z chromosome evolution and gene expression across 12 paleognaths, several of whose genomes have recently been sequenced. We confirm at the genomic level that most paleognaths retain large PARs. As in other birds, we find that all paleognaths have incomplete dosage compensation on the regions of the Z chromosome homologous to degenerated portions of the W (differentiated regions), but we find no evidence for enrichments of male-biased genes in PARs. We find limited evidence for increased evolutionary rates (faster-Z) either across the chromosome or in differentiated regions for most paleognaths with large PARs, but do recover signals of faster-Z evolution in tinamou species with mostly degenerated W chromosomes, similar to the pattern seen in neognaths. Unexpectedly, in some species, PAR-linked genes evolve faster on average than genes on autosomes, suggested by diverse genomic features to be due to reduced efficacy of selection in paleognath PARs. Our analysis shows that paleognath Z chromosomes are atypical at the genomic level, but the evolutionary forces maintaining largely homomorphic sex chromosomes in these species remain elusive.

scholarly journals Chromosomal Spreading of Microsatellites and (TTAGGG)n Sequences in the Characidium zebra and C. gomesi Genomes (Characiformes: Crenuchidae)

2016 ◽  
Vol 149 (3) ◽  
pp. 182-190 ◽  
Author(s):  
Marcela B. Pucci ◽  
Patricia Barbosa ◽  
Viviane Nogaroto ◽  
Mara C. Almeida ◽  
Roberto F. Artoni ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Sex Chromosomes ◽  
Dna Sequences ◽  
Tandem Repeats ◽  
Additional Data ◽  
Sex Chromosome ◽  
Binding Motif ◽  
W Chromosome ◽  
Repeat Sequences ◽  
Heteromorphic Sex Chromosomes

Sex chromosome evolution involves the accumulation of repeat sequences such as multigenic families, noncoding repetitive DNA (satellite, minisatellite, and microsatellite), and mobile elements such as transposons and retrotransposons. Most species of Characidium exhibit heteromorphic ZZ/ZW sex chromosomes; the W is characterized by an intense accumulation of repetitive DNA including dispersed satellite DNA sequences and transposable elements. The aim of this study was to analyze the distribution pattern of 18 different tandem repeats, including (GATA)n and (TTAGGG)n, in the genomes of C. zebra and C. gomesi, especially in the C. gomesi W chromosome. In the C. gomesi W chromosome, weak signals were seen for (CAA)10, (CAC)10, (CAT)10, (CGG)10, (GAC)10, and (CA)15 probes. (GA)15 and (TA)15 hybridized to the autosomes but not to the W chromosome. The (GATA)n probe hybridized to the short arms of the W chromosome as well as the (CG)15 probe. The (GATA)n repeat is known to be a protein-binding motif. GATA-binding proteins are necessary for the decondensation of heterochromatic regions that hold coding genes, especially in some heteromorphic sex chromosomes that may keep genes related to oocyte development. The (TAA)10 repeat is accumulated in the entire W chromosome, and this microsatellite accumulation is probably involved in the sex chromosome differentiation process and crossover suppression in C. gomesi. These additional data on the W chromosome DNA composition help to explain the evolution of sex chromosomes in Characidium.

LTR retrotransposons in the dioecious plant Silene latifolia

Genome ◽  
2002 ◽  
Vol 45 (4) ◽  
pp. 745-751 ◽  
Author(s):  
Sachihiro Matsunaga ◽  
Fumi Yagisawa ◽  
Maki Yamamoto ◽  
Wakana Uchida ◽  
Shunsuke Nakao ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Sex Chromosome ◽  
Silene Latifolia ◽  
Ltr Retrotransposons ◽  
Dioecious Plant ◽  
Dioecious Species ◽  
Y Chromosomes ◽  
Genus Silene ◽  
Silene Species

Conserved domains of two types of LTR retrotransposons, Ty1–copia- and Ty3–gypsy-like retrotransposons, were isolated from the dioecious plant Silene latifolia, whose sex is determined by X and Y chromosomes. Southern hybridization analyses using these retrotransposons as probes resulted in identical patterns from male and female genomes. Fluorescence in situ hybridization indicated that these retrotransposons do not accumulate specifically in the sex chromosomes. These results suggest that recombination between the sex chromosomes of S. latifolia has not been severely reduced. Conserved reverse transcriptase regions of Ty1–copia-like retrotransposons were isolated from 13 different Silene species and classified into two major families. Their categorization suggests that parallel divergence of the Ty1–copia-like retrotransposons occurred during the differentiation of Silene species. Most functional retrotransposons from three dioecious species, S. latifolia, S. dioica, and S. diclinis, fell into two clusters. The evolutionary dynamics of retrotransposons implies that, in the genus Silene, dioecious species evolved recently from gynodioecious species.Key words: retrotransposon, dioecious plant, sex chromosome.

Sibling species and sex chromosome differentiation in Simulium neornatipes (Diptera: Simuliidae)

1984 ◽  
Vol 26 (3) ◽  
pp. 318-325 ◽  
Author(s):  
D. G. Bedo
Keyword(s):  
Polytene Chromosome ◽  
Sibling Species ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Close Association ◽  
Chromosome Analysis ◽  
Sex Linkage ◽  
Direct Role ◽  
Chromosome Differentiation ◽  
Close Relationship

Polytene chromosome analysis of five Simulium neornatipes populations not only confirms the existence of the two sibling species, S. neornatipes 1 and 2, proposed earlier but reveals a third. S. neornatipes 3. These sibling species share a common standard polytene chromosome banding sequence which differs from the Australian S. ornatipes complex standard by five fixed inversions. The sharing of polymorphic inversions between the ornatipes and neornatipes complexes indicates their close relationship. The neornatipes species are distinguished from each other by additional fixed inversions and differentiated sex chromosomes. Extensive sex chromosome differentiation involving chromosome III has occurred in S. neornatipes 1 and 2. A period of incomplete sex-linkage allowing reassortment of inversions must have preceded the currently observed strong sex-linkage of differentiated sex chromosomes to account for the complex array of sex chromosomes found. The close association of sex chromosome differentiation with speciation in black flies is discussed in relation to appropriate speciation mechanisms. It is concluded that the rearrangements themselves have no direct role in the speciation process.Key words: sibling species, sex chromosomes, Simuliidae.

scholarly journals Long-term sex reversal by oestradiol in amniotes with heteromorphic sex chromosomes

2006 ◽  
Vol 2 (3) ◽  
pp. 378-381 ◽  
Author(s):  
Steven Freedberg ◽  
Rachel M Bowden ◽  
Michael A Ewert ◽  
Dale R Sengelaub ◽  
Craig E Nelson
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Sex Reversal ◽  
Normal Female ◽  
Long Term Effects ◽  
Turtle Species ◽  
Ideal System ◽  
Heteromorphic Sex Chromosomes ◽  
Do So

Oestradiol application during embryonic development reverses the sex of male embryos and results in normal female differentiation in reptiles lacking heteromorphic sex chromosomes, but fails to do so in birds and mammals with heteromorphic sex chromosomes. It is not clear whether the evolution of heteromorphic sex chromosomes in amniotes is accompanied by insensitivity to oestradiol, or if the association between oestradiol insensitivity and heteromorphic sex chromosomes can be attributable to phylogenetic constraints in these taxa. Turtles provide an ideal system to examine the potential relationship between oestradiol insensitivity and sex chromosome heteromorphy, since there are species with heteromorphic sex chromosomes that are closely related to species lacking heteromorphic sex chromosomes. We investigated this relationship by examining the long-term effects of oestradiol-17β application on sex determination in Staurotypus triporcatus and Staurotypus salvinii , two turtle species with male heterogamety. After raising the turtles in the lab for 3 years, we found follicular and Müllerian duct morphology in oestradiol-treated turtles that was identical to that of untreated females. The lasting sex reversal suggests that the evolutionary transition between systems lacking heteromorphic sex chromosomes and those with heteromorphic sex chromosomes is not constrained by a fundamental mechanistic difference.

scholarly journals Evolutionary dynamics of sex chromosomes of paleognathous birds

2018 ◽  
Author(s):  
Luohao Xu ◽  
Simon Yung Wa Sin ◽  
Phil Grayson ◽  
Scott V. Edwards ◽  
Timothy B. Sackton
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Z Chromosome ◽  
Recombination Suppression ◽  
Evolutionary Forces ◽  
Genomic Level ◽  
Standard Models ◽  
Pseudoautosomal Regions

AbstractStandard models of sex chromosome evolution propose that recombination suppression leads to the degeneration of the heterogametic chromosome, as is seen for the Y chromosome in mammals and the W chromosome in most birds. Unlike other birds, paleognaths (ratites and tinamous) possess large non-degenerate regions on their sex chromosomes (PARs or pseudoautosomal regions). It remains unclear why these large PARs are retained over more than 100 MY, and how this retention impacts the evolution of sex chromosomes within this system. To address this puzzle, we analysed Z chromosome evolution and gene expression across 12 paleognaths, several of whose genomes have recently been sequenced. We confirm at the genomic level that most paleognaths retain large PARs. As in other birds, we find that all paleognaths have incomplete dosage compensation on the regions of the Z chromosome homologous to degenerated portions of the W (differentiated regions or DRs), but we find no evidence for enrichments of male-biased genes in PARs. We find limited evidence for increased evolutionary rates (faster-Z) either across the chromosome or in DRs for most paleognaths with large PARs, but do recover signals of faster-Z evolution in tinamou species with mostly degenerated W chromosomes, similar to the pattern seen in neognaths. Unexpectedly, in some species PAR-linked genes evolve faster on average than genes on autosomes, suggested by diverse genomic features to be due to reduced efficacy of selection in paleognath PARs. Our analysis shows that paleognath Z chromosomes are atypical at the genomic level, but the evolutionary forces maintaining largely homomorphic sex chromosomes in these species remain elusive.

scholarly journals Evolutionary Variability of W-Linked Repetitive Content in Lacertid Lizards

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 531
Author(s):  
Grzegorz Suwala ◽  
Marie Altmanová ◽  
Sofia Mazzoleni ◽  
Emmanouela Karameta ◽  
Panayiotis Pafilis ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Phylogenetic Signal ◽  
Z Chromosome ◽  
Specific Gene ◽  
W Chromosome ◽  
Squamate Reptiles ◽  
Lacertid Lizards ◽  
Species Specific

Lacertid lizards are a widely radiated group of squamate reptiles with long-term stable ZZ/ZW sex chromosomes. Despite their family-wide homology of Z-specific gene content, previous cytogenetic studies revealed significant variability in the size, morphology, and heterochromatin distribution of their W chromosome. However, there is little evidence about the accumulation and distribution of repetitive content on lacertid chromosomes, especially on their W chromosome. In order to expand our knowledge of the evolution of sex chromosome repetitive content, we examined the topology of telomeric and microsatellite motifs that tend to often accumulate on the sex chromosomes of reptiles in the karyotypes of 15 species of lacertids by fluorescence in situ hybridization (FISH). The topology of the above-mentioned motifs was compared to the pattern of heterochromatin distribution, as revealed by C-banding. Our results show that the topologies of the examined motifs on the W chromosome do not seem to follow a strong phylogenetic signal, indicating independent and species-specific accumulations. In addition, the degeneration of the W chromosome can also affect the Z chromosome and potentially also other parts of the genome. Our study provides solid evidence that the repetitive content of the degenerated sex chromosomes is one of the most evolutionary dynamic parts of the genome.

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