scholarly journals Gene-level, but not chromosome-wide, divergence between a very young house fly proto-Y chromosome and its homologous proto-X chromosome

2020 ◽  
Author(s):  
Jae Hak Son ◽  
Richard P. Meisel
Keyword(s):  
Gene Expression ◽  
Y Chromosome ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
House Fly ◽  
Evolutionary Divergence ◽  
Y Chromosomes ◽  
Mitochondrial Functions ◽  
Xx Males ◽  
Y Chromosome Evolution

AbstractX and Y chromosomes are usually derived from a pair of homologous autosomes, which then diverge from each other over time. Although Y-specific features have been characterized in sex chromosomes of various ages, the earliest stages of Y chromosome evolution remain elusive. In particular, we do not know whether early stages of Y chromosome evolution consist of changes to individual genes or happen via chromosome-scale divergence from the X. To address this question, we quantified divergence between young proto-X and proto-Y chromosomes in the house fly, Musca domestica. We compared proto-sex chromosome sequence and gene expression between genotypic (XY) and sex-reversed (XX) males. We find evidence for sequence divergence between genes on the proto-X and proto-Y, including five genes with mitochondrial functions. There is also an excess of genes with divergent expression between the proto-X and proto-Y, but the number of genes is small. This suggests that individual proto-Y genes, but not the entire proto-Y chromosome, have diverged from the proto-X. We identified one gene, encoding an axonemal dynein assembly factor (which functions in sperm motility), that has higher expression in XY males than XX males because of a disproportionate contribution of the proto-Y allele to gene expression. The up-regulation of the proto-Y allele may be favored in males because of this gene’s function in spermatogenesis. The evolutionary divergence between proto-X and proto-Y copies of this gene, as well as the mitochondrial genes, is consistent with selection in males affecting the evolution of individual genes during early Y chromosome evolution.

scholarly journals Gene-Level, but Not Chromosome-Wide, Divergence between a Very Young House Fly Proto-Y Chromosome and Its Homologous Proto-X Chromosome

2020 ◽  
Author(s):  
Jae Hak Son ◽  
Richard P Meisel
Keyword(s):  
Gene Expression ◽  
Y Chromosome ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
House Fly ◽  
Evolutionary Divergence ◽  
Y Chromosomes ◽  
Mitochondrial Functions ◽  
Xx Males ◽  
Y Chromosome Evolution

Abstract X and Y chromosomes are usually derived from a pair of homologous autosomes, which then diverge from each other over time. Although Y-specific features have been characterized in sex chromosomes of various ages, the earliest stages of Y chromosome evolution remain elusive. In particular, we do not know whether early stages of Y chromosome evolution consist of changes to individual genes or happen via chromosome-scale divergence from the X. To address this question, we quantified divergence between young proto-X and proto-Y chromosomes in the house fly, Musca domestica. We compared proto-sex chromosome sequence and gene expression between genotypic (XY) and sex-reversed (XX) males. We find evidence for sequence divergence between genes on the proto-X and proto-Y, including five genes with mitochondrial functions. There is also an excess of genes with divergent expression between the proto-X and proto-Y, but the number of genes is small. This suggests that individual proto-Y genes, but not the entire proto-Y chromosome, have diverged from the proto-X. We identified one gene, encoding an axonemal dynein assembly factor (which functions in sperm motility), that has higher expression in XY males than XX males because of a disproportionate contribution of the proto-Y allele to gene expression. The upregulation of the proto-Y allele may be favored in males because of this gene’s function in spermatogenesis. The evolutionary divergence between proto-X and proto-Y copies of this gene, as well as the mitochondrial genes, is consistent with selection in males affecting the evolution of individual genes during early Y chromosome evolution.

scholarly journals Y-chromosome haplotypes of varying differentiation to the X are not associated with male fitness in common frogs

2019 ◽  
Author(s):  
Paris Veltsos ◽  
Nicolas Rodrigues ◽  
Tania Studer ◽  
Wen-Juan Ma ◽  
Roberto Sermier ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Sex Chromosome Evolution ◽  
Chromosome Differentiation ◽  
Y Chromosomes ◽  
Male Phenotype ◽  
Xx Males

AbstractThe canonical model of sex-chromosome evolution assigns a key role to sexually antagonistic (SA) genes on the arrest of recombination and ensuing degeneration of Y chromosomes. This assumption cannot be tested in organisms with highly differentiated sex chromosomes, such as mammals or birds, owing to the lack of polymorphism. Fixation of SA alleles, furthermore, might be the consequence rather than the cause of recombination arrest. Here we focus on a population of common frogs (Rana temporaria) where XY males with genetically differentiated Y chromosomes (non-recombinant Y haplotypes) coexist with both XY° males with proto-Y chromosomes (only differentiated from X chromosomes in the immediate vicinity of the candidate sex-determining locus Dmrt1) and XX males with undifferentiated sex chromosomes (genetically identical to XX females). Our study shows no effect of sex-chromosome differentiation on male phenotype, mating success or fathering success. Our conclusions rejoin genomic studies that found no differences in gene expression between XY, XY° and XX males. Sexual dimorphism in common frogs seems to result from the differential expression of autosomal genes rather than sex-linked SA genes. Among-male variance in sex-chromosome differentiation is better explained by a polymorphism in the penetrance of alleles at the sex locus, resulting in variable levels of sex reversal (and thus of X-Y recombination in XY females), independent of sex-linked SA genes.Impact SummaryHumans, like other mammals, present highly differentiated sex chromosomes, with a large, gene-rich X chromosome contrasting with a small, gene-poor Y chromosome. This differentiation results from a process that started approximately 160 Mya, when the Y first stopped recombining with the X. How and why this happened, however, remain controversial. According to the canonical model, the process was initiated by sexually antagonistic selection; namely, selection on the proto-Y chromosome for alleles that were beneficial to males but detrimental to females. The arrest of XY recombination then allowed such alleles to be only transmitted to sons, not to daughters. Although appealing and elegant, this model can no longer be tested in mammals, as it requires a sex-chromosome system at an incipient stage of evolution. Here we focus on a frog that displays within-population polymorphism is sex-chromosome differentiation, where XY males with differentiated chromosomes coexist with XX males lacking Y chromosomes. We find no effect of sex-chromosome differentiation on male phenotype or mating success, opposing expectations from the standard model. Sex linked genes do not seem to have a disproportionate effect on sexual dimorphism. From our results, sexually antagonistic genes show no association with sex-chromosome differentiation in frogs, which calls for alternative models of sex-chromosome evolution.

scholarly journals The effects of haploid selection on Y chromosome evolution in two closely related dioecious plants

2018 ◽  
Author(s):  
George Sandler ◽  
Felix E.G. Beaudry ◽  
Spencer C.H. Barrett ◽  
Stephen I. Wright
Keyword(s):  
Gene Expression ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Sex Chromosome Evolution ◽  
Y Chromosomes ◽  
Expression Bias ◽  
Haploid Selection ◽  
Plant Sex

AbstractThe evolution of sex chromosomes is usually considered to be driven by sexually antagonistic selection in the diploid phase. However, selection during the haploid gametic phase of the lifecycle has recently received theoretical attention as possibly playing a central role in sex chromosome evolution, especially in plants where gene expression in the haploid phase is extensive. In particular, male-specific haploid selection might favour the linkage of pollen beneficial alleles to male sex determining regions on incipient Y chromosomes. This linkage might then allow such alleles to further specialise for the haploid phase. Purifying haploid selection is also expected to slow the degeneration of Y-linked genes expressed in the haploid phase. Here, we examine the evolution of gene expression in flower buds and pollen of two species of Rumex to test for signatures of haploid selection acting during plant sex chromosome evolution. We find that genes with high ancestral pollen expression bias occur more often on sex chromosomes than autosomes and that genes on the Y chromosome are more likely to become enriched for pollen expression bias. We also find that genes with low expression in pollen are more likely to be lost from the Y chromosome. Our results suggest that sex-specific haploid selection during the gametophytic stage of the lifecycle may be a major contributor to several features of plant sex chromosome evolution.

scholarly journals New Insights into Mammalian Sex Chromosome Structure and Evolution from High-quality Bovine X and Y Chromosome Sequences

2019 ◽  
Author(s):  
Ruijie Liu ◽  
Wai Yee Low ◽  
Rick Tearle ◽  
Sergey Koren ◽  
Jay Ghurye ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Immune Modulation ◽  
Sex Chromosome ◽  
Inflammatory Responses ◽  
Structure Evolution ◽  
Pseudoautosomal Region ◽  
Evolutionary Divergence ◽  
High Quality ◽  
Global Regulators ◽  
Y Chromosomes

Abstract Background Mammalian X chromosomes are mainly euchromatic with a similar size and structure among species whereas Y chromosomes are smaller, have undergone substantial evolutionary changes and accumulated male specific genes and genes involved in sex determination. The PAR is conserved on the X and Y and pair during meiosis. The structure, evolution and function of mammalian sex chromosomes is still poorly understood because few species have high quality sex chromosome assemblies. Results Here we report the first bovine sex chromosome assemblies that include the complete pseudoautosomal region (PAR) spanning 6.84 Mb and three Y chromosome X-degenerate (X-d) regions. We show that the ruminant PAR comprises 31 genes and is similar to the PAR of pig and dog but extends further than those of human and horse. Differences in the pseudoautosomal boundaries are consistent with evolutionary divergence times. Conclusions A bovidae-specific expansion of members of the lipocalin gene family in the PAR may reflect immune-modulation and anti-inflammatory responses that contribute to parasite resistance in ruminants. Comparison of the X-d regions of Y chromosomes across species reveal five conserved X-Y gametologs, which are global regulators of gene activity, and may have a fundamental role in mammalian sexual dimorphism.

scholarly journals New Insights into Mammalian Sex Chromosome Structure and Evolution from High-quality Bovine X and Y Chromosome Sequences

2019 ◽  
Author(s):  
Ruijie Liu ◽  
Wai Yee Low ◽  
Rick Tearle ◽  
Sergey Koren ◽  
Jay Ghurye ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Immune Modulation ◽  
Sex Chromosome ◽  
Inflammatory Responses ◽  
Structure Evolution ◽  
Pseudoautosomal Region ◽  
Evolutionary Divergence ◽  
High Quality ◽  
Global Regulators ◽  
Y Chromosomes

Abstract Background Mammalian X chromosomes are mainly euchromatic with a similar size and structure among species whereas Y chromosomes are smaller, have undergone substantial evolutionary changes and accumulated male specific genes and genes involved in sex determination. The PAR is conserved on the X and Y and pair during meiosis. The structure, evolution and function of mammalian sex chromosomes is still poorly understood because few species have high quality sex chromosome assemblies. Results Here we report the first bovine sex chromosome assemblies that include the complete pseudoautosomal region (PAR) spanning 6.84 Mb and three Y chromosome X-degenerate (X-d) regions. We show that the ruminant PAR comprises 31 genes and is similar to the PAR of pig and dog but extends further than those of human and horse. Differences in the pseudoautosomal boundaries are consistent with evolutionary divergence times. Conclusions A bovidae-specific expansion of members of the lipocalin gene family in the PAR may reflect immune-modulation and anti-inflammatory responses that contribute to parasite resistance in ruminants. Comparison of the X-d regions of Y chromosomes across species reveal five conserved X-Y gametologs, which are global regulators of gene activity, and may have a fundamental role in mammalian sexual dimorphism.

Molecular characterization of a mouse Y chromosomal repetitive sequence amplified in distantly related species in the genus Mus

Genome ◽  
1993 ◽  
Vol 36 (3) ◽  
pp. 588-593 ◽  
Author(s):  
Yutaka Nishioka ◽  
Becky M. Dolan ◽  
Laila Zahed
Keyword(s):  
Y Chromosome ◽  
Repetitive Sequence ◽  
Chromosome Evolution ◽  
Fragment Length Polymorphism ◽  
Gc Content ◽  
Y Chromosomes ◽  
Mouse Species ◽  
Y Chromosome Evolution

This report describes a 1.1 kb long mouse Y chromosomal sequence designated 142-4. It has a 42% GC content and is rich in short direct and inverted repeats. 142-4 related sequences are repeated about 200 times in the Mus musculus Y chromosome and their distribution was visualized by in situ hybridization. 142-4 detected a restriction fragment length polymorphism that differentiated between the M. m. musculus type and the M. m. domesticus type Y chromosome. Southern blot analysis of DNAs isolated from a panel of mouse species showed that 142-4 related sequences were amplified in the Y chromosomes of M. minutoides, M. musculus, M. saxicola, M. spicilegus, and M. spretus but not in those of M. caroli, M. cookii, and M. pahari. These results suggest that 142-4 related sequences are evolutionary unstable and their accumulation patterns do not correlate with the known phylogenetic relationships of mouse species in the genus Mus.Key words: mouse Y chromosome, repetitive sequence, Mus, sequence amplification, Y chromosome evolution.

scholarly journals New Insights into Mammalian Sex Chromosome Structure and Evolution from High-quality Bovine X and Y Chromosome Sequences

2019 ◽  
Author(s):  
Ruijie Liu ◽  
Wai Yee Low ◽  
Rick Tearle ◽  
Sergey Koren ◽  
Jay Ghurye ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Immune Modulation ◽  
Sex Chromosome ◽  
Inflammatory Responses ◽  
Structure Evolution ◽  
Pseudoautosomal Region ◽  
Evolutionary Divergence ◽  
High Quality ◽  
Global Regulators ◽  
Y Chromosomes

Abstract Background Mammalian X chromosomes are mainly euchromatic with a similar size and structure among species whereas Y chromosomes are smaller, have undergone substantial evolutionary changes and accumulated male specific genes and genes involved in sex determination. The PAR is conserved on the X and Y and pair during meiosis. The structure, evolution and function of mammalian sex chromosomes is still poorly understood because few species have high quality sex chromosome assemblies. Results Here we report the first bovine sex chromosome assemblies that include the complete pseudoautosomal region (PAR) spanning 6.84 Mb and three Y chromosome X-degenerate (X-d) regions. We show that the ruminant PAR comprises 31 genes and is similar to the PAR of pig and dog but extends further than those of human and horse. Differences in the pseudoautosomal boundaries are consistent with evolutionary divergence times. Conclusions A bovidae-specific expansion of members of the lipocalin gene family in the PAR may reflect immune-modulation and anti-inflammatory responses that contribute to parasite resistance in ruminants. Comparison of the X-d regions of Y chromosomes across species reveal five conserved X-Y gametologs, which are global regulators of gene activity, and may have a fundamental role in mammalian sexual dimorphism.

scholarly journals New insights into mammalian sex chromosome structure and evolution using high-quality sequences from bovine X and Y chromosomes

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Ruijie Liu ◽  
Wai Yee Low ◽  
Rick Tearle ◽  
Sergey Koren ◽  
Jay Ghurye ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Immune Modulation ◽  
Sex Chromosome ◽  
Inflammatory Responses ◽  
Structure Evolution ◽  
Pseudoautosomal Region ◽  
Evolutionary Divergence ◽  
Chromosome X ◽  
High Quality ◽  
Y Chromosomes

Abstract Background Mammalian X chromosomes are mainly euchromatic with a similar size and structure among species whereas Y chromosomes are smaller, have undergone substantial evolutionary changes and accumulated male specific genes and genes involved in sex determination. The pseudoautosomal region (PAR) is conserved on the X and Y and pair during meiosis. The structure, evolution and function of mammalian sex chromosomes, particularly the Y chromsome, is still poorly understood because few species have high quality sex chromosome assemblies. Results Here we report the first bovine sex chromosome assemblies that include the complete PAR spanning 6.84 Mb and three Y chromosome X-degenerate (X-d) regions. The PAR comprises 31 genes, including genes that are missing from the X chromosome in current cattle, sheep and goat reference genomes. Twenty-nine PAR genes are single-copy genes and two are multi-copy gene families, OBP, which has 3 copies and BDA20, which has 4 copies. The Y chromosome X-d1, 2a and 2b regions contain 11, 2 and 2 gametologs, respectively. Conclusions The ruminant PAR comprises 31 genes and is similar to the PAR of pig and dog but extends further than those of human and horse. Differences in the pseudoautosomal boundaries are consistent with evolutionary divergence times. A bovidae-specific expansion of members of the lipocalin gene family in the PAR reported here, may affect immune-modulation and anti-inflammatory responses in ruminants. Comparison of the X-d regions of Y chromosomes across species revealed that five of the X-Y gametologs, which are known to be global regulators of gene activity and candidate sexual dimorphism genes, are conserved.

scholarly journals Sex determination in the fly Megaselia scalaris, a model system for primary steps of sex chromosome evolution.

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 1097-1104
Author(s):  
W Traut
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Chromosome Pair ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Random Amplified Polymorphic Dna ◽  
Sex Chromosome Evolution ◽  
Y Chromosomes ◽  
Megaselia Scalaris ◽  
Primary Male

Abstract The fly Megaselia scalaris Loew possesses three homomorphic chromosome pairs; 2 is the sex chromosome pair in two wild-type laboratory stocks of different geographic origin (designated "original" sex chromosome pair in this paper). The primary male-determining function moves at a very low rate to other chromosomes, thereby creating new Y chromosomes. Random amplified polymorphic DNA markers obtained by polymerase chain reaction with single decamer primers and a few available phenotypic markers were used in testcrosses to localize the sex-determining loci and to define the new sex chromosomes. Four cases are presented in which the primary male-determining function had been transferred from the original Y chromosome to a new locus either on one of the autosomes or on the original X chromosome, presumably by transposition. In these cases, the sex-determining function had moved to a different locus without an obvious cotransfer of other Y chromosome markers. Thus, with Megaselia we are afforded an experimental system to study the otherwise hypothetical primary stages of sex chromosome evolution. An initial molecular differentiation is apparent even in the new sex chromosomes. Molecular differences between the original X and Y chromosomes illustrate a slightly more advanced stage of sex chromosome evolution.

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