Journal articles: 'XO sex-chromosome system'

1

Hodgkin, Jonathan. "Primary sex determination in the nematode C. elegans." Development 101, Supplement (1987): 5–16. http://dx.doi.org/10.1242/dev.101.supplement.5.

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Most nematodes have XO male/XX female sex determination. C. elegans is anomalous, having XX hermaphrodites rather than females. The hermaphrodite condition appears to result from the modification of a basic male/female sex-determination system, which permits both spermatogenesis and oogenesis to occur within a female soma. This modification is achieved by a germ-line-specific control acting at one step in a cascade of autosomal regulatory genes, which respond to X-chromosome dosage and direct male, female, or hermaphrodite development. Mutations of one of these genes can be used to construct artificial strains with ZZ male/WZ female sex determination. Primary sex determination normally depends on the ratio of X chromosomes to autosomes, as in Drosophila, and there appear to be multiple sites on the X chromosome that contribute to this ratio. Also, as in Drosophila, X-chromosome expression is compensated to equalize gene activity in XX and XO animals. Interactions between dosage compensation and sex determination are described and discussed.

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Sharman, GB, RL Hughes, and DW Cooper. "The Chromosomal Basis of Sex-Differentiation in Marsupials." Australian Journal of Zoology 37, no. 3 (1989): 451. http://dx.doi.org/10.1071/zo9890451.

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Data on ten intersexual marsupials, eight of which were of known karyotype, are presented and reviewed. Three of the intersexes were known or suspected XO/XX or XO/XX/XXX, two were XXY, one was XXY/XY/XX and two were XY in sex chromosome constitution. In all three intersexes which had an XO cell line, but in which no Y chromosome was found in any cell, a small empty scrotum was found to one side of the midline or in the midline. Those which had a non-midline scrotum had mammary tissue on the opposite side and a partial or complete pouch. The intersex with the midline scrotum had no pouch or mammary glands. Unilateral or bilateral putative spermatic cords, not containing a ductus deferens, descended to the scrotum, but in all other respects the internal reproductive systems were like those of normal XX female marsupials. Intersexes with no Y chromosome were of female body size when adult. The XXY and XXY/XY/XX intersexes all had complete pouches and mammary glands and none had a scrotum. All had well developed male internal reproductive systems and undescended testis-like gonads, and were of intermediate body size. Both XY intersexes also had complete pouches and mammary glands, no scrotum, and male-type internal reproductive systems with undescended testes which were normal except for absence of post- primary spermatocyte stages of spermatogenesis. One XY intersex was fully adult and it did not differ from normal XY males of the same species in body measurements, body weight and secondary sex coloration. One of the intersexes of unknown karyotype, but of suspected XX chromosome constitution, was morphologically like the XO/XX/XXX mosaic with a centrally placed scrotum. The other, of suspected XY chromosome constitution, was essentially comparable to the XY intersexes. The data are interpreted, at the whole chromosome level, as follows. In the presence of a single active X chromosome scrotal and spermatic cord development were initiated, whereas they were inhibited in the presence of two X chromosomes. Complete scrotal development completely inhibited, and unilateral scrotal development partly inhibited, pouch and mammary gland development. The Y chromosome was responsible for primary gonadal sex and, apparently through production of MIS, eliminated the Miillerian (i.e. female) sex ducts. Development of a male type of reproductive system was dependent on presence of a Y chromosome and, apparently, androgen production from testes or testis-like gonads. At the gene level the data may be interpreted in terms of a hypothetical S or 'switch' locus, carried on the X chromosome, which induced scrotal development in single dose and a pouch and mammary glands in double dose. If this hypothesis is correct, it would explain the occurrence of incomplete X-chromosome inactivation in marsupials; complete X-inactivation is impossible in marsupials because it would leave each female with a scrotum, not a pouch.

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SANTIAGO-BLAY, JORGE A., and NIILO VIRKKI. "On the XO sex chromosome system of Aulacoscelis melanocera Stal (Aulacoscelinae: Chrysomelidae: Coleoptera)." Hereditas 111, no. 2 (2008): 99–102. http://dx.doi.org/10.1111/j.1601-5223.1989.tb00383.x.

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Hodgkin, Jonathan. "Exploring the Envelope: Systematic Alteration in the Sex-Determination System of the Nematode Caenorhabditis elegans." Genetics 162, no. 2 (2002): 767–80. http://dx.doi.org/10.1093/genetics/162.2.767.

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Abstract The natural sexes of the nematode Caenorhabditis elegans are the self-fertilizing hermaphrodite (XX) and the male (XO). The underlying genetic pathway controlling sexual phenotype has been extensively investigated. Mutations in key regulatory genes have been used to create a series of stable populations in which sex is determined not by X chromosome dosage, but in a variety of other ways, many of which mimic the diverse sex-determination systems found in different animal species. Most of these artificial strains have male and female sexes. Each of seven autosomal genes can be made to adopt a role as the primary determinant of sex, and each of the five autosomes can carry the primary determinant, thereby becoming a sex chromosome. Strains with sex determination by fragment chromosomes, episomes, compound chromosomes, or environmental factors have also been constructed. The creation of these strains demonstrates the ease with which one sex-determination system can be transformed into another.

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Harvey, S. C., and M. E. Viney. "Sex Determination in the Parasitic Nematode Strongyloides ratti." Genetics 158, no. 4 (2001): 1527–33. http://dx.doi.org/10.1093/genetics/158.4.1527.

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Abstract The parasitic nematode Strongyloides ratti reproduces by both parthenogenesis and sexual reproduction, but its genetics are poorly understood. Cytological evidence suggests that sex determination is an XX/XO system. To investigate this genetically, we isolated a number of sex-linked DNA markers. One of these markers, Sr-mvP1, was shown to be single copy and present at a higher dose in free-living females than in free-living males. The inheritance of two alleles of Sr-mvP1 by RFLP analysis was consistent with XX female and XO male genotypes. Analysis of the results of sexual reproduction demonstrated that all progeny inherit the single paternal X chromosome and one of the two maternal X chromosomes. Therefore, all stages of the S. ratti life cycle, with the exception of the free-living males, are XX and genetically female. These findings are considered in relation to previous analyses of S. ratti and to other known sex determination systems.

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Xu, Bo, Yankai Li, and Baozhen Hua. "A chromosomal investigation of four species of Chinese Panorpidae (Insecta, Mecoptera)." Comparative Cytogenetics 7, no. (3) (2013): 229–39. https://doi.org/10.3897/compcytogen.v7i3.5500.

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The male adults of four species of the Chinese Panorpidae in Mecoptera were cytogenetically studied using conventional squashing procedures. The results show that their sex-chromosome system belongs to the XO type, with n = 19 + X(O) in Panorpa emarginata Cheng, 1949 and Panorpa dubia Chou & Wang, 1981, n = 23 + X(O) in Panorpa sp., and n = 20 + X(O) in Neopanorpa lui Chou & Ran, 1981. X chromosomes of these species usually appear dot-shaped in late prophase I and are easily differentiated from autosomal bivalents. Meiosis in these Panorpidae lacks typical diplotene and diakinesis. In late prophase I, pairs of homologous chromosomes remain parallel in a line and show no evidence of crossing-over. Some of them even appear as a single unit because of extremely intimate association, all with a tendency of increasing condensation. The evolutionary significance of their chromosomal differences and the achiasmatic meiosis of Panorpidae are briefly discussed.

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de Souza Valentim, Francisco Carlos, Jorge Ivan Rebelo Porto, Luiz Antonio Carlos Bertollo, Maria Claudia Gross, and Eliana Feldberg. "XX/XO, a rare sex chromosome system in Potamotrygon freshwater stingray from the Amazon Basin, Brazil." Genetica 141, no. 7-9 (2013): 381–87. http://dx.doi.org/10.1007/s10709-013-9737-2.

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STREIT, ADRIAN. "How to become a parasite without sex chromosomes: a hypothesis for the evolution of Strongyloides spp. and related nematodes." Parasitology 141, no. 10 (2014): 1244–54. http://dx.doi.org/10.1017/s003118201400064x.

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SUMMARYParasitic lifestyles evolved many times independently. Just within the phylum Nematoda animal parasitism must have arisen at least four times. Switching to a parasitic lifestyle is expected to lead to changes in various life history traits including reproductive strategies. Parasitic nematode worms of the genus Strongyloides represent an interesting example to study these processes because they are still capable of forming facultative free-living generations in between parasitic ones. The parasitic generation consists of females only, which reproduce parthenogenetically. The sex in the progeny of the parasitic worms is determined by environmental cues, which control a, presumably ancestral, XX/XO chromosomal sex determining system. In some species the X chromosome is fused with an autosome and one copy of the X-derived sequences is removed by sex-specific chromatin diminution in males. Here I propose a hypothesis for how today's Strongyloides sp. might have evolved from a sexual free-living ancestor through dauer larvae forming free-living and facultative parasitic intermediate stages.

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9

Vitturi, Roberto, Mariastella Colomba, Nicola Volpe, Antonella Lannino, and Mario Zunino. "Evidence for male XO sex-chromosome system in Pentodon bidens punctatum (Coleoptera Scarabaeoidea: Scarabaeidae) with X-linked 18S-28S rDNA clusters." Genes & Genetic Systems 78, no. 6 (2003): 427–32. http://dx.doi.org/10.1266/ggs.78.427.

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10

Alves, Anderson Luís, Claudio Oliveira, Mauro Nirchio, Ángel Granado, and Fausto Foresti. "Karyotypic relationships among the tribes of Hypostominae (Siluriformes: Loricariidae) with description of XO sex chromosome system in a Neotropical fish species." Genetica 128, no. 1-3 (2006): 1–9. http://dx.doi.org/10.1007/s10709-005-0715-1.

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11

Hasegawa, Koichi, Manuel M. Mota, Kazuyoshi Futai, and Johji Miwa. "Chromosome structure and behaviour in Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae) germ cells and early embryo." Nematology 8, no. 3 (2006): 425–34. http://dx.doi.org/10.1163/156854106778493475.

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AbstractChromosome structure and behaviour in both meiosis of the germ cells and mitosis of the embryo from fertilisation to the two-cell stage in Bursaphelenchus xylophilus were examined by DAPI staining and three-dimensional reconstruction of serial-section images from confocal laser-scanning microscopy. By this method, each chromosome's shape and behaviour were clearly visible in early embryogenesis from fertilisation through the formation and fusion of the male and female pronuclei to the first mitotic division. The male pronucleus was bigger than that of the female, although the oocyte is larger and richer in nutrients than the sperm. From the shape of the separating chromosomes at anaphase, the mitotic chromosomes appeared to be polycentric or holocentric rather than monocentric. Each chromosome was clearly distinguishable in the male and female germ cells, pronuclei of the one-cell stage embryo, and the early embryonic nuclei. The haploid number of chromosomes (N) was six (2n = 12), and all chromosomes appeared similar. The chromosome pair containing the ribosomal RNA-coding site was visualised by fluorescence in situ hybridisation. Unlike the sex determination system in Caenorhabditis elegans (XX in hermaphrodite and XO in male), the system for B. xylophilus may consist of an XX female and an XY male.

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12

Spence, John R. "Introgressive hybridization in Heteroptera: the example of Limnoporus Stål (Gerridae) species in western Canada." Canadian Journal of Zoology 68, no. 8 (1990): 1770–82. http://dx.doi.org/10.1139/z90-258.

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Populations of the pondskaters, Limnoporous dissortis and Limnoporous notabilis, hybridize extensively in the Cordilleran region of western Canada. In laboratory crosses using L. dissortis from central Alberta and L. notabilis from southwestern British Columbia, most eggs are fertilized and begin development, but only ca. 50% of the eggs hatch and nearly all F1 hybrid adults are males. F1 hybrid males are fertile in backcrosses to females of both species, although egg hatch is reduced and mainly male progeny result from crosses to females of the paternal species. These species both have an XO sex chromosome system, and the foregoing results suggest that either products of genes on X chromosomes of the two species are incompatible or that they are incompatible with heterospecific cytoplasmic elements. Males of L. dissortis are more successful at interspecific copulations than are those of L. notabilis, perhaps because they more frequently adopt aggressive mating behaviour that circumvents premating barriers. Although gene pools of these two species are partially isolated by both pre- and post-mating barriers, there has been large-scale exchange of genes at autosomal loci, and significant introgression occurs over a large geographic area. Introgression is asymmetric, with genes of L. dissortis tending to flow disproportionately into L. notabilis populations, reflecting differences between the species in mating behaviour and dispersal tendencies. Because these two species are not closest relatives, I conclude that reticulations can be important considerations in the evolution of semiaquatic bugs. A literature survey shows that interspecific hybridization occurs in a number of heteropteran families, although partial barriers to gene flow are common.

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13

Petitpierre, Eduard. "Cytogenetics, cytotaxonomy and chromosomal evolution of Chrysomelinae revisited (Coleoptera, Chrysomelidae)." ZooKeys 157 (December 21, 2011): 67–79. https://doi.org/10.3897/zookeys.157.1339.

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Nearly 260 taxa and chromosomal races of subfamily Chrysomelinae have been chromosomally analyzed showing a wide range of diploid numbers from 2n = 12 to 2n = 50, and four types of male sex-chromosome systems. with the parachute-like ones Xyp and XYp clearly prevailing (79.0%), but with the XO well represented too (19.75%). The modal haploid number for chrysomelines is n = 12 (34.2%) although it is not probably the presumed most plesiomorph for the whole subfamily, because in tribe Timarchini the modal number is n = 10 (53.6%) and in subtribe Chrysomelina n = 17 (65.7%). Some well sampled genera, such as Timarcha, Chrysolina and Cyrtonus, are variable in diploid numbers, whereas others, like Chrysomela, Paropsisterna, Oreina and Leptinotarsa, are conservative and these differences are discussed. The main shifts in the chromosomal evolution of Chrysomelinae seems to be centric fissions and pericentric inversions but other changes as centric fusions are also clearly demonstrated. The biarmed chromosome shape is the prevalent condition, as found in most Coleoptera, although a fair number of species hold a few uniarmed chromosomes at least. A significant negative correlation between the haploid numbers and the asymmetry in size of karyotypes (r = -0.74) has been found from a large sample of 63 checked species of ten different genera. Therefore, the increases in haploid number are generally associated with a higher karyotype symmetry.

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Matiz-Ceron, Luisa, Miki Okuno, Takehiko Itoh, et al. "Loss of one X and the Y chromosome changes the configuration of the X inactivation center in the genus Tokudaia." Cytogenetic and Genome Research, May 16, 2024. http://dx.doi.org/10.1159/000539294.

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Introduction: X chromosome inactivation (XCI) is an essential mechanism for dosage compensation between females and males in mammals. In females, XCI is controlled by a complex, conserved locus termed the X inactivation center (Xic), in which the lncRNA Xist is the key regulator. However, little is known about the Xic in species with unusual sex chromosomes. The genus Tokudaia includes three rodent species endemic to Japan. Tokudaia osimensis (TOS) and Tokudaia tokunoshimensis (TTO) lost the Y chromosome (XO/XO), while Tokudaia muenninki (TMU) acquired a neo-X region by fusion of the X chromosome and an autosome (XX/XY). We compared the gene location and structure in the Xic among Tokudaia species. Methods: Gene structure of nine genes in Xic were predicted, and the gene location and genome sequences of Xic were compared between mouse and Tokudaia species. The expression level of gene was confirmed by TPM calculation using RNA-seq data. Results: Compared to mouse, the Xic gene order and location were conserved in Tokudaia species. However, remarkable structure changes were observed in lncRNA genes, Xist and Tsix, in the XO/XO species. In Xist, important functional repeats, B-, C-, D-, and E-repeats, were partially or completely lost due to deletions in these species. RNA-seq data showed that female-specific expression patterns of Xist and Tsix were confirmed in TMU, however not in the XO/XO species. Additionally, three deletions and one inversion were confirmed in the intergenic region between Jpx and Ftx in the XO/XO species. Conclusion: Our findings indicate that even if the Xist and Tsix lncRNAs are expressed, they are incapable of producing a successful and lasting XCI in the XO/XO species. We hypothesized that the significant structure change in intergenic region of Jpx-Ftx resulted in the inability to perform the X chromosome inactivation, and, as a result, a lack of Xist expression. Our results collectively suggest that structural changes in the Xic occurred in the ancestral lineage of XO/XO species, likely due to the loss of one X chromosome and the Y chromosome and a consequence of the degradation of XCI system.

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Yoshida, Kohta, Hanh Witte, Ryo Hatashima, et al. "Rapid chromosome evolution and acquisition of thermosensitive stochastic sex determination in nematode androdioecious hermaphrodites." Nature Communications 15, no. 1 (2024). http://dx.doi.org/10.1038/s41467-024-53854-6.

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AbstractThe factors contributing to evolution of androdioecy, the coexistence of hermaphrodites and males such as in Caenorhabditis elegans, remains poorly known. However, nematodes exhibit androdioecy in at last 13 genera with the predatory genus Pristionchus having seven independent transitions towards androdioecy. Nonetheless, associated genomic architecture and sex determination mechanisms are largely known from Caenorhabditis. Here, studying 47 Pristionchus species, we observed repeated chromosome evolution which abolished the ancestral XX/XO sex chromosome system. Two phylogenetically unrelated androdioecious Pristionchus species have no genomic differences between sexes and mating hermaphrodites with males resulted in hermaphroditic offspring only. We demonstrate that stochastic sex determination is influenced by temperature in P. mayeri and P. entomophagus, and CRISPR engineering indicated a conserved role of the transcription factor TRA-1 in P. mayeri. Chromosome-level genome assemblies and subsequent genomic analysis of related Pristionchus species revealed stochastic sex determination to be derived from XY sex chromosome systems through sex chromosome-autosome fusions. Thus, rapid karyotype evolution, sex chromosome evolution and evolvable sex determination mechanisms are general features of this genus, and represent a dynamic background against which androdioecy has evolved recurrently. Future studies might indicate that stochastic sex determination is more common than currently appreciated.

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Prowse, Thomas AA, Fatwa Adikusuma, Phillip Cassey, Paul Thomas, and Joshua V. Ross. "A Y-chromosome shredding gene drive for controlling pest vertebrate populations." eLife 8 (February 15, 2019). http://dx.doi.org/10.7554/elife.41873.

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Self-replicating gene drives that modify sex ratios or infer a fitness cost could be used to control populations of invasive alien species. The targeted deletion of Y sex chromosomes using CRISPR technology offers a new approach for sex bias that could be incorporated within gene-drive designs. We introduce a novel gene-drive strategy termed Y-CHromosome deletion using Orthogonal Programmable Endonucleases (Y-CHOPE), incorporating a programmable endonuclease that ‘shreds’ the Y chromosome, thereby converting XY males into fertile XO females. Firstly, we demonstrate that the CRISPR/Cas12a system can eliminate the Y chromosome in embryonic stem cells with high efficiency (c. 90%). Next, using stochastic, individual-based models of a pest mouse population, we show that a Y-shredding drive that progressively depletes the pool of XY males could effect population eradication through mate limitation. Our molecular and modeling data suggest that a Y-CHOPE gene drive could be a viable tool for vertebrate pest control.

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17

Li, Zheng, Allen Z. Xue, Gerald P. Maeda, Yiyuan Li, Paul D. Nabity, and Nancy A. Moran. "Phylloxera and aphids show distinct features of genome evolution despite similar reproductive modes." Molecular Biology and Evolution, December 9, 2023. http://dx.doi.org/10.1093/molbev/msad271.

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Abstract Genomes of aphids (family Aphididae) show several unusual evolutionary patterns. In particular, within the XO sex determination system of aphids, the X chromosome exhibits a lower rate of interchromosomal rearrangements, fewer highly expressed genes, and faster evolution at nonsynonymous sites compared to the autosomes. In contrast, other hemipteran lineages have similar rates of interchromosomal rearrangement for autosomes and X chromosomes. One possible explanation for these differences is the aphid’s life cycle of cyclical parthenogenesis, where multiple asexual generations alternate with one sexual generation. If true, we should see similar features in the genomes of Phylloxeridae, an outgroup of aphids which also undergoes cyclical parthenogenesis. To investigate this, we generated a chromosome-level assembly for the grape phylloxera, an agriculturally important species of Phylloxeridae, and identified its single X chromosome. We then performed synteny analysis using the phylloxerid genome and 30 high-quality genomes of aphids and other hemipteran species. Unexpectedly, we found that the phylloxera does not share aphids’ patterns of chromosome evolution. By estimating interchromosomal rearrangement rates on an absolute time scale, we found that rates are elevated for aphid autosomes compared to their X chromosomes, but this pattern does not extend to the phylloxera branch. Potentially, the conservation of X chromosome gene content is due to selection on XO males that appear in the sexual generation. We also examined gene duplication patterns across Hemiptera and uncovered horizontal gene transfer events contributing to phylloxera evolution.

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Vitturi, Roberto, Mariastella Colomba, Nicola Volpe, Antonella Lannino, and Mario Zunino. "Evidence for male XO sex-chromosome system in Pentodon bidens punctatum (Coleoptera Scarabaeoidea: Scarabaeidae) with X-linked 18S-28S rDNA clusters." February 19, 2004. https://doi.org/10.1266/ggs.78.427.

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Journal articles on the topic 'XO sex-chromosome system'

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