Complex Events in the Evolution of the Human Pseudoautosomal Region 2 (PAR2)

Charchar, Fadi J.; Svartman, Marta; El‐Mogharbel, Nisrine; Ventura, Mario; Kirby, Patrick J.; Matarazzo, Maria R.; Ciccodicola, Alfredo; Rocchi, Mariano; D’Esposito, Maurizio; Graves, Jennifer A. Marshall

doi:10.1101/gr.390503

Cited by 62 publications

(59 citation statements)

References 27 publications

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“…In mammals, the gene order in the X chromosomes has been conserved across such distantly related species as human, cat, horse, cattle, and elephant, with the exception of mouse (22)(23)(24)(25)(26). In the human X and chicken Z, gene trafficking and sequence expansion have been detected, using comparisons with orthologous autosomal segments of other species (12)(13)(14). Given its recent origin, the differences in gene content between papaya and V. monoica are surprising.…”

Section: Discussionmentioning

confidence: 97%

“…Although other studies have compared the ancient human X and chicken Z chromosomes with their orthologous autosomal regions in distantly related species (12)(13)(14), our study is unique in being a detailed direct comparison between a newly evolved X-specific chromosomal region and its nonsex chromosomal homolog in a close relative. This comparison This article is a PNAS Direct Submission.…”

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confidence: 99%

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Rapid divergence and expansion of the X chromosome in papaya

Gschwend

Tong

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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X chromosomes have long been thought to conserve the structure and gene content of the ancestral autosome from which the sex chromosomes evolved. We compared the recently evolved papaya sex chromosomes with a homologous autosome of a close relative, the monoecious Vasconcellea monoica, to infer changes since recombination stopped between the papaya sex chromosomes. We sequenced 12 V. monoica bacterial artificial chromosomes, 11 corresponding to the papaya X-specific region, and 1 to a papaya autosomal region. The combined V. monoica X-orthologous sequences are much shorter (1.10 Mb) than the corresponding papaya region (2.56 Mb). Given that the V. monoica genome is 41% larger than that of papaya, this finding suggests considerable expansion of the papaya X; expansion is supported by a higher repetitive sequence content of the X compared with the papaya autosomal sequence. The alignable regions include 27 transcriptencoding sequences, only 6 of which are functional X/V. monoica gene pairs. Sequence divergence from the V. monoica orthologs is almost identical for papaya X and Y alleles; the Carica-Vasconcellea split therefore occurred before the papaya sex chromosomes stopped recombining, making V. monoica a suitable outgroup for inferring changes in papaya sex chromosomes. The papaya X and the hermaphrodite-specific region of the Y h chromosome and V. monoica have all gained and lost genes, including a surprising amount of changes in the X.Carica papaya | gene gains and losses | sex chromosome evolution | suppression of recombination | centromere of X chromosome P apaya (Carica papaya L.) is a trioecious tropical fruit crop that has a nascent XY sex chromosome system, in which the sex determining region occupies a small fraction of the X/Y chromosome pair (1-3). Papaya has two slightly different Y chromosomes that diverged about 73,000 y ago, Y in males and Y h in hermaphrodites (4). All genotypes without X chromosomes (YY, YY h , and Y h Y h ) are lethal in early development, resulting in 25% aborted seeds in selfed hermaphrodites and in crosses between hermaphrodites and males (5), indicating that both Y types have lost at least one gene essential for development.Papaya belongs to the family Caricaceae, with six genera and 35 species, 32 of which are dioecious, two are trioecious (with male, female, and hermaphrodite individuals) and one, Vasconcellea monoica, is monoecious (with male and female flowers on a single plant). The predominance of dioecious species suggests that dioecy is ancestral in this family and that the trioecious and monoecious species evolved recently. V. monoica has no sex chromosomes, because there is no sexual dimorphism among individuals, and there is a single sequence corresponding to each of the several papaya X/Y h gene pairs tested, whereas distinct X and Y alleles were detected in several dioecious Vasconcellea species (6), which indicates that the sex chromosomes in these species are homologous with those in papaya.V. monoica therefore provides an opportunity to compare the recentl...

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Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

Rapid divergence and expansion of the X chromosome in papaya

Gschwend

Tong

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…It should be noted here that certain mammalian species including human, cow, and dog but not rodents have another Ant, Ant3 on the tip of the X chromosome (Table 1) (40,54). Human ANT3 is encoded on Xp22 within pseudoautosomal region 1 (40). This region is highly conserved between X and Y chromosomes and is known to escape from sex chromosome inactivation during male meiosis (42,44,54).…”

Section: Discussionmentioning

confidence: 99%

“…This suggests that Ant4 may have been generated by a standard gene duplication event in mammalian ancestors. It should be noted here that certain mammalian species including human, cow, and dog but not rodents have another Ant, Ant3 on the tip of the X chromosome (Table 1) (40,54). Human ANT3 is encoded on Xp22 within pseudoautosomal region 1 (40).…”

Section: Discussionmentioning

confidence: 99%

Evolutionarily Conserved Mammalian Adenine Nucleotide Translocase 4 Is Essential for Spermatogenesis

Brower

Rodić

Seki

et al. 2007

Journal of Biological Chemistry

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The adenine nucleotide translocases (Ant) facilitate the transport of ADP and ATP by an antiport mechanism across the inner mitochondrial membrane, thus playing an essential role in cellular energy metabolism. We recently identified a novel member of the Ant family in mouse, Ant4, of which gene configuration as well as amino acid homology is well conserved among mammals. The conservation of Ant4 in mammals, along with the absence of Ant4 in nonmammalian species, suggests a unique and indispensable role for this ADP/ATP carrier in mammalian development. Of interest, in contrast to its paralog Ant2, which is encoded by the X chromosome and ubiquitously expressed in somatic cells, Ant4 is encoded by an autosome and selectively expressed in testicular germ cells. Immunohistochemical examination as well as RNA expression analysis using separated spermatogenic cell types revealed that Ant4 expression was particularly high in spermatocytes. When we generated Ant4-deficient mice by targeted disruption, a significant reduction in testicular size was observed without any other distinguishable abnormalities in the mice. Histological examination as well as stage-specific gene expression analysis in adult and neonatal testes revealed a severe reduction of spermatocytes accompanied by increased apoptosis. Subsequently, the Ant4-deficient male mice were infertile. Taken together, these data elucidated the indispensable role of Ant4 in murine spermatogenesis. Considering the unique conservation and chromosomal location of the Ant family genes in mammals, the Ant4 gene may have arisen in mammalian ancestors and been conserved in mammals to serve as the sole and essential mitochondrial ADP/ATP carrier during spermatogenesis where the sex chromosome-linked Ant2 gene is inactivated.

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“…Several additions to the mammalian sex chromosomes are inferred, including the recent addition of a second PAR2. Genes in both the present-day PARs are autosomal in marsupials, and are on different marsupial chromosomes (Charchar et al, 2003).…”

Section: What Causes Suppressed Recombination?mentioning

confidence: 99%

Steps in the evolution of heteromorphic sex chromosomes

2005

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We review some recently published results on sex chromosomes in a diversity of species. We focus on several fish and some plants whose sex chromosomes appear to be 'young', as only parts of the chromosome are nonrecombining, while the rest is pseudoautosomal. However, the age of these systems is not yet very clear. Even without knowing what proportions of their genes are genetically degenerate, these cases are of great interest, as they may offer opportunities to study in detail how sex chromosomes evolve. In particular, we review evidence that recombination suppression occurs progressively in evolutionarily independent cases, suggesting that selection drives loss of recombination over increasingly large regions. We discuss how selection during the period when a chromosome is adapting to its role as a Y chromosome might drive such a process.

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Complex Events in the Evolution of the Human Pseudoautosomal Region 2 (PAR2)

Cited by 62 publications

References 27 publications

Rapid divergence and expansion of the X chromosome in papaya

Rapid divergence and expansion of the X chromosome in papaya

Evolutionarily Conserved Mammalian Adenine Nucleotide Translocase 4 Is Essential for Spermatogenesis

Steps in the evolution of heteromorphic sex chromosomes

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