The Location of the Pseudoautosomal Boundary in Silene latifolia

Y-chromosomes contain a non-recombining region (NRY), and in many organisms it was shown that the NRY expanded over time. How and why the NRY expands remains unclear. Young sex chromosomes, where NRY expansion occurred recently or is on-going, offer an opportunity to study the causes of this process. Here, we used the plant Silene latifolia, where sex chromosomes evolved ~11 million years ago, to study the location of the boundary between the NRY and the recombining pseudoautosomal region (PAR). The previous work devoted to the NRY/PAR boundary in S. latifolia was based on a handful of genes with locations approximately known from the genetic map. Here, we report the analysis of 86 pseudoautosomal and sex-linked genes adjacent to the S. latifolia NRY/PAR boundary to establish the location of the boundary more precisely. We take advantage of the dense genetic map and polymorphism data from wild populations to identify 20 partially sex-linked genes located in the “fuzzy boundary”, that rarely recombines in male meiosis. Genes proximal to this fuzzy boundary show no evidence of recombination in males, while the genes distal to this partially-sex-linked region are actively recombining in males. Our results provide a more accurate location for the PAR boundary in S. latifolia, which will help to elucidate the causes of PAR boundary shifts leading to NRY expansion over time.

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Sex Chromosomes and Psychosis

The British Journal of Psychiatry ◽

10.1192/bjp.153.5.675 ◽

1988 ◽

Vol 153 (5) ◽

pp. 675-683 ◽

Cited By ~ 125

Author(s):

T. J. Crow

Keyword(s):

Sex Chromosomes ◽

Distal Segment ◽

Depressive Illness ◽

Male Meiosis ◽

High Rate ◽

Pseudoautosomal Region ◽

Psychiatric Disease ◽

Same Sex ◽

Y Chromosomes ◽

Gender Influences

Although the incidence of the recurrent psychoses (bipolar affective illness and schizophrenia) in the two sexes is approximately equal, gender influences a number of aspects of major psychiatric disease: unipolar depressive illness is twice as common in females, onset of schizophrenia is earlier and outcome is worse in males, and pairs of psychotic first-degree relatives are more often than expected of the same sex. In addition, sex chromosomal aneuploidies (e.g. XXY and XXX) are more frequent in patients with psychosis. Some of these findings can be explained if there is a major locus of predisposition to psychiatric disease in the ‘pseudoautosomal’ region of the sex chromosomes – that distal segment of the short arms in which there is genetic exchange between X and Y chromosomes at male meiosis. A gene located here would be transmitted in an autosomal manner, but would be passed above chance expectation to children of the same sex when inherited through a male. In that this segment of the sex chromosomes is subject to a high rate of recombination (which could generate new mutations), and may include determinants of brain lateralisation, it appears that the pseudoautosomal region could carry the genes which predispose to the major psychoses.

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Differences in recombination frequencies during female and male meioses of the sex chromosomes of the medaka, Oryzias latipes

Genetics Research ◽

10.1017/s0016672301005109 ◽

2001 ◽

Vol 78 (1) ◽

pp. 23-30 ◽

Cited By ~ 65

Author(s):

MARIKO KONDO ◽

ERIKO NAGAO ◽

HIROSHI MITANI ◽

AKIHIRO SHIMA

Keyword(s):

Genetic Map ◽

Sex Chromosomes ◽

Sex Chromosome ◽

Oryzias Latipes ◽

Male Recombination ◽

Male And Female ◽

Y Chromosomes ◽

Genetic Length ◽

Expressed Sequence ◽

Group 1

In the medaka, Oryzias latipes, sex is determined chromosomally. The sex chromosomes differ from those of mammals in that the X and Y chromosomes are highly homologous. Using backcross panels for linkage analysis, we mapped 21 sequence tagged site (STS) markers on the sex chromosomes (linkage group 1). The genetic map of the sex chromosome was established using male and female meioses. The genetic length of the sex chromosome was shorter in male than in female meioses. The region where male recombination is suppressed is the region close to the sex-determining gene y, while female recombination was suppressed in both the telomeric regions. The restriction in recombination does not occur uniformly on the sex chromosome, as the genetic map distances of the markers are not proportional in male and female recombination. Thus, this observation seems to support the hypothesis that the heterogeneous sex chromosomes were derived from suppression of recombination between autosomal chromosomes. In two of the markers, Yc-2 and Casp6, which were expressed sequence-tagged (EST) sites, polymorphisms of both X and Y chromosomes were detected. The alleles of the X and Y chromosomes were also detected in O. curvinotus, a species related to the medaka. These markers could be used for genotyping the sex chromosomes in the medaka and other species, and could be used in other studies on sex chromosomes.

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Human Spermatogenesis Tolerates Massive Size Reduction of the Pseudoautosomal Region

Genome Biology and Evolution ◽

10.1093/gbe/evaa168 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1961-1964

Author(s):

Maki Fukami ◽

Yasuko Fujisawa ◽

Hiroyuki Ono ◽

Tomoko Jinno ◽

Tsutomu Ogata

Keyword(s):

Animal Studies ◽

Male Meiosis ◽

Size Reduction ◽

Pseudoautosomal Region ◽

Minimal Size ◽

Y Chromosomes ◽

Cytogenetic Analyses ◽

Human Spermatogenesis ◽

Complete Deletion ◽

Chromosomal Recombination

Abstract Mammalian male meiosis requires homologous recombination between the X and Y chromosomes. In humans, such recombination occurs exclusively in the short arm pseudoautosomal region (PAR1) of 2.699 Mb in size. Although it is known that complete deletion of PAR1 causes spermatogenic arrest, no studies have addressed to what extent male meiosis tolerates PAR1 size reduction. Here, we report two families in which PAR1 partial deletions were transmitted from fathers to their offspring. Cytogenetic analyses revealed that a ∼400-kb segment at the centromeric end of PAR1, which accounts for only 14.8% of normal PAR1 and 0.26% and 0.68% of the X and Y chromosomes, respectively, is sufficient to mediate sex chromosomal recombination during spermatogenesis. These results highlight the extreme recombinogenic activity of human PAR1. Our data, in conjunction with previous findings from animal studies, indicate that the minimal size requirement of mammalian PARs to maintain male fertility is fairly small.

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Rapid Y degeneration and dosage compensation in plant sex chromosomes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1508454112 ◽

2015 ◽

Vol 112 (42) ◽

pp. 13021-13026 ◽

Cited By ~ 80

Author(s):

Alexander S. T. Papadopulos ◽

Michael Chester ◽

Kate Ridout ◽

Dmitry A. Filatov

Keyword(s):

Sex Chromosomes ◽

Large Scale ◽

De Novo ◽

Silene Latifolia ◽

Stop Codons ◽

Y Chromosomes ◽

Evolutionary Trajectories ◽

Plant Sex Chromosomes ◽

Two Kingdoms ◽

Y Degeneration

The nonrecombining regions of animal Y chromosomes are known to undergo genetic degeneration, but previous work has failed to reveal large-scale gene degeneration on plant Y chromosomes. Here, we uncover rapid and extensive degeneration of Y-linked genes in a plant species, Silene latifolia, that evolved sex chromosomes de novo in the last 10 million years. Previous transcriptome-based studies of this species missed unexpressed, degenerate Y-linked genes. To identify sex-linked genes, regardless of their expression, we sequenced male and female genomes of S. latifolia and integrated the genomic contigs with a high-density genetic map. This revealed that 45% of Y-linked genes are not expressed, and 23% are interrupted by premature stop codons. This contrasts with X-linked genes, in which only 1.3% of genes contained stop codons and 4.3% of genes were not expressed in males. Loss of functional Y-linked genes is partly compensated for by gene-specific up-regulation of X-linked genes. Our results demonstrate that the rate of genetic degeneration of Y-linked genes in S. latifolia is as fast as in animals, and that the evolutionary trajectories of sex chromosomes are similar in the two kingdoms.

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LTR retrotransposons in the dioecious plant Silene latifolia

Genome ◽

10.1139/g02-026 ◽

2002 ◽

Vol 45 (4) ◽

pp. 745-751 ◽

Cited By ~ 28

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, Ty1copia- and Ty3gypsy-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 Ty1copia-like retrotransposons were isolated from 13 different Silene species and classified into two major families. Their categorization suggests that parallel divergence of the Ty1copia-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.

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Y chromosome specific markers and the evolution of dioecy in the genus Silene

Genome ◽

10.1139/g97-094 ◽

1998 ◽

Vol 41 (2) ◽

pp. 141-147 ◽

Cited By ~ 17

Author(s):

Y Hi Zhang ◽

Veronica S Stilio ◽

Farah Rehman ◽

Amy Avery ◽

David Mulcahy ◽

...

Keyword(s):

Y Chromosome ◽

Sex Chromosomes ◽

Silene Latifolia ◽

Dioecious Species ◽

Sequence Characterized Amplified Region ◽

Y Chromosomes ◽

Heteromorphic Sex Chromosomes ◽

Males And Females ◽

Genus Silene ◽

Evolution Of Dioecy

Sex determination in plants has been most thoroughly investigated in Silene latifolia, a dioecious species possessing heteromorphic sex chromosomes. We have identified several new Y chromosome linked RAPD markers and converted these to more reliable sequence characterized amplified region (SCAR) markers by cloning the RAPD fragments and developing longer primers. Of the primer pairs for seven SCARs, five amplify a single, unique fragment from the DNA of male S. latifolia. Two sets of primers also amplify additional fragments common to males and females. Homology between the X and Y chromosomes is sufficient to allow the amplification of fragments from females under less stringent PCR conditions. Five of the SCARs also distinguish between the sexes of closely related dioecious taxa of the section Elisanthe, but not between the sexes of distantly related dioecious species. These markers will be useful for continued investigations into the evolution of sex, phylogenetic relationships among taxa, and population dynamics of sex ratios in the genus Silene.Key words: Melandrium, RAPDs, sex chromosomes, SCARs.

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Genomic imprinting mediates dosage compensation in a young plant XY system

10.1101/179044 ◽

2017 ◽

Cited By ~ 2

Author(s):

Aline Muyle ◽

Niklaus Zemp ◽

Cécile Fruchard ◽

Radim Cegan ◽

Jan Vrana ◽

...

Keyword(s):

Gene Expression ◽

Genomic Imprinting ◽

Dosage Compensation ◽

Sex Chromosomes ◽

Evolutionary Biology ◽

Early Stage ◽

Silene Latifolia ◽

Negative Effects ◽

Y Chromosomes ◽

Sex Determination System

This preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100044).Sex chromosomes have repeatedly evolved from a pair of autosomes1. Consequently, X and Y chromosomes initially have similar gene content, but ongoing Y degeneration leads to reduced Y gene expression and eventual Y gene loss. The resulting imbalance in gene expression between Y genes and the rest of the genome is expected to reduce male fitness, especially when protein networks have components from both autosomes and sex chromosomes. A diverse set of dosage compensating mechanisms that alleviates these negative effects has been described in animals2–4. However, the early steps in the evolution of dosage compensation remain unknown and dosage compensation is poorly understood in plants5. Here we show a novel dosage compensation mechanism in the evolutionarily young XY sex determination system of the plant Silene latifolia. Genomic imprinting results in higher expression from the maternal X chromosome in both males and females. This compensates for reduced Y expression in males but results in X overexpression in females and may be detrimental. It could represent a transient early stage in the evolution of dosage compensation. Our finding has striking resemblance to the first stage proposed by Ohno for the evolution of X inactivation in mammals.

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C-banded karyotypes of two Silene species with heteromorphic sex chromosomes

Genome ◽

10.1139/g01-143 ◽

2002 ◽

Vol 45 (2) ◽

pp. 243-252 ◽

Cited By ~ 26

Author(s):

Aleksandra Grabowska-Joachimiak ◽

Andrzej Joachimiak

Keyword(s):

Sex Chromosomes ◽

Sex Chromosome ◽

Silene Latifolia ◽

Silene Dioica ◽

Dna Amount ◽

Metaphase Chromosomes ◽

X Chromosomes ◽

C Banding ◽

Y Chromosomes ◽

Heteromorphic Sex Chromosomes

Mitotic metaphase chromosomes of Silene latifolia (white campion) and Silene dioica (red campion) were studied and no substantial differences between the conventional karyotypes of these two species were detected. The classification of chromosomes into three distinct groups proposed for S. latifolia by Ciupercescu and colleagues was considered and discussed. Additionally, a new small satellite on the shorter arm of homobrachial chromosome 5 was found. Giemsa C-banded chromosomes of the two analysed species show many fixed and polymorphic heterochromatic bands, mainly distally and centromerically located. Our C-banding studies provided an opportunity to better characterize the sex chromosomes and some autosome types, and to detect differences between the two Silene karyotypes. It was shown that S. latifolia possesses a larger amount of polymorphic heterochromatin, especially of the centromeric type. The two Silene sex chromosomes are easily distinguishable not only by length or DNA amount differences but also by their Giemsa C-banding patterns. All Y chromosomes invariably show only one distally located band, and no other fixed or polymorphic bands on this chromosome were observed in either species. The X chromosomes possess two terminally located fixed bands, and some S. latifolia X chromosomes also have an extra-centric segment of variable length. The heterochromatin amount and distribution revealed by our Giemsa C-banding studies provide a clue to the problem of sex chromosome and karyotype evolution in these two closely related dioecious Silene species.Key words: dioecious plant, Silene dioica, Silene latifolia, karyotype, sex chromosomes, heterochromatin, C-banding.

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Sex-determination and sex chromosomes are shared across the radiation of dioecious Nepenthes pitcher plants

10.1101/240259 ◽

2017 ◽

Author(s):

Mathias Scharmann ◽

T. Ulmar Grafe ◽

Faizah Metali ◽

Alex Widmer

Keyword(s):

Sex Determination ◽

Sex Chromosomes ◽

High Throughput Sequencing ◽

Silene Latifolia ◽

Wild Populations ◽

Sequencing Data ◽

Pitcher Plants ◽

Determination System ◽

Sex Determination System ◽

Male Specific

AbstractPlants with separate sexes (dioecy) represent a minority but dioecy has evolved multiple times independently in plants. Our understanding of sex determination systems in plants and of the ecological factors and molecular changes associated with the evolution of dioecy remain limited. Here, we study the sex-determination system in dioecious plants that lack heteromorphic sex chromosomes and are not amenable to controlled breeding: Nepenthes pitcher plants. We genotyped wild populations of flowering males and females of three Nepenthes taxa using ddRAD-seq, and sequenced a male inflorescence transcriptome. We developed a novel statistical tool (privacy rarefaction) to distinguish true sex-specificity from stochastic noise in high-throughput sequencing data. Our results support XY-systems in all three Nepenthes taxa and in Silene latifolia which was used as a positive control for its known XY-system. The male-specific region of the Y chromosome showed little conservation among the three Nepenthes taxa, except for the essential pollen development gene DYT1 which was also male-specific in additional taxa. Hence, this homomorphic XY sex-determination system likely has a unique origin older than the crown of the genus Nepenthes at c. 17.7 My. In addition to the characterisation of the previously unknown sex chromosomes of Nepenthes, our work contributes an innovative, highly sensitive statistical method to efficiently detect sex-specific genomic regions in wild populations in general.

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Sex chromosome pairing mediated by euchromatic homology in Drosophila male meiosis

10.1101/854877 ◽

2019 ◽

Author(s):

Christopher A. Hylton ◽

Katie Hansen ◽

Andrew Bourgeois ◽

John E. Tomkiel

Keyword(s):

Sex Chromosomes ◽

Sex Chromosome ◽

Intergenic Spacer ◽

Male Meiosis ◽

Early Prophase ◽

Dna Breaks ◽

Late Prophase ◽

Prophase I ◽

Y Chromosomes ◽

Meiosis I

ABSTRACTTo maintain proper ploidy, haploid sex cells must undergo two subsequent meiotic divisions. During meiosis I, homologs pair and remain conjoined until segregation at anaphase. Drosophila melanogaster spermatocytes are unique in that the canonical events of meiosis I including synaptonemal complex (SC) formation, double-strand DNA breaks, and chiasmata are absent. Sex chromosomes pair at intergenic spacer sequences within the heterochromatic rDNA while euchromatin is required to pair and segregate autosomal homologies, suggesting that pairing may be limited to specific sequences. However, previous work generated from genetic segregation assays or observations of late prophase I/prometaphase I chromosome associations fail to differentiate pairing from conjunction. Here, we separately examined the capability of X euchromatin to pair and conjoin using an rDNA-deficient X and a series of Dp(1;Y) chromosomes. Genetic assays showed that duplicated X euchromatin can substitute for endogenous rDNA pairing sites. Segregation was not proportional to homology length, and pairing could be mapped to nonoverlapping sequences within a single Dp(1;Y). Using fluorescent in situ hybridization (FISH) to early prophase I spermatocytes, we showed that pairing occurred with high fidelity at all homologies tested. Pairing was unaffected by the presence of X rDNA, nor could it be explained by rDNA magnification. By comparing genetic and cytological data, we determined that centromere proximal pairings were best at segregation. Segregation was dependent on the conjunction protein Stromalin in Meiosis while the autosomal-specific Teflon was dispensable. Overall, our results suggest that pairing may occur at all homologies, but there may be sequence or positional requirements for conjunction.ARTICLE SUMMARYDrosophila males have evolved a unique system of chromosome segregation in meiosis that lacks recombination. Chromosomes pair at selected sequences suggesting that early steps of meiosis may also differ in this organism. Using Y chromosomes carrying portions of X material, we show that pairing between sex chromosomes can be mediated by sequences other than the previously identified rDNA pairing sites. We propose that pairing may simply be homology-based and may not differ from canonical meiosis observed in females. The main difference in males may be that conjunctive mechanisms that join homologs in the absence of crossovers.

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