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Sample records for sex ratio chromosome

  1. Comparative AFLP reveals paternal sex ratio chromosome specific DNA sequences in the parasitoid wasp Trichogramma kaykai

    NARCIS (Netherlands)

    Vugt, van J.J.F.A.; Hulst, van der R.G.M.; Pruijssers, A.; Verbaarschot, P.G.H.; Stouthamer, R.; Jong, de H.

    2009-01-01

    The parasitoid wasp Trichogramma kaykai with a haplo-diploid sex determination has a B chromosome called the paternal sex ratio (PSR) chromosome that confers paternal genome loss during early embryogenesis, resulting in male offspring. So far, it is not well known whether the PSR chromosome has

  2. Influence of postzygotic reproductive isolation on the interspecific transmission of the paternal sex ratio chromosome in Trichogramma

    NARCIS (Netherlands)

    Jeong, G.S.; Stouthamer, R.

    2006-01-01

    The paternal sex ratio (PSR) chromosome is a supernumerary chromosome that causes the destruction of the paternal chromosome set in the first mitosis in a fertilized egg. It is known from parasitoid wasps in the genera Nasonia and Trichogramma (Hymenoptera). In these haplodiploids, the egg

  3. The paternal-sex-ratio (PSR) chromosome in natural populations of Nasonia (Hymenoptera Chalcidoidea)

    NARCIS (Netherlands)

    Beukeboom, L.W.; Werren, J.H.

    2000-01-01

    Selfish genetic elements may be important in promoting evolutionary change. Paternal sex ratio (PSR) is a selfish B chromosome that causes all-male families in the haplodiploid parasitic wasp Nasonia vitripennis, by inducing paternal genome loss in fertilized eggs. The natural distribution and

  4. Sex chromosome repeats tip the balance towards speciation.

    Science.gov (United States)

    O'Neill, Michael J; O'Neill, Rachel J

    2018-04-06

    Because sex chromosomes, by definition, carry genes that determine sex, mutations that alter their structural and functional stability can have immediate consequences for the individual by reducing fertility, but also for a species by altering the sex ratio. Moreover, the sex-specific segregation patterns of heteromorphic sex chromosomes make them havens for selfish genetic elements that not only create sub-optimal sex ratios, but can also foster sexual antagonism. Compensatory mutations to mitigate antagonism or return sex ratios to a Fisherian optimum can create hybrid incompatibility and establish reproductive barriers leading to species divergence. The destabilizing influence of these selfish elements is often manifest within populations as copy number variants (CNVs) in satellite repeats and transposable elements (TE) or as CNVs involving sex determining genes, or genes essential to fertility and sex chromosome dosage compensation. This review catalogs several examples of well-studied sex chromosome CNVs in Drosophilids and mammals that underlie instances of meiotic drive, hybrid incompatibility and disruptions to sex differentiation and sex chromosome dosage compensation. While it is difficult to pinpoint a direct cause/effect relationship between these sex chromosome CNVs and speciation, it is easy to see how their effects in creating imbalances between the sexes, and the compensatory mutations to restore balance, can lead to lineage splitting and species formation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  5. The origin of a selfish B chromosome triggering paternal sex ratio in the parasitoid wasp Trichogramma kaykai

    NARCIS (Netherlands)

    Vugt, van J.J.F.A.; Jong, de J.H.S.G.M.; Stouthamer, R.

    2009-01-01

    This study uses molecular and cytogenetic methods to determine the origin of a B chromosome in some males of the wasp Trichogramma kaykai. This so-called paternal sex ratio (PSR) chromosome transmits only through sperm and shortly after fertilization triggers degeneration of the paternal genome,

  6. Normal Female Germ Cell Differentiation Requires the Female X Chromosome to Autosome Ratio and Expression of Sex-Lethal in DROSOPHILA MELANOGASTER

    OpenAIRE

    Schüpbach, Trudi

    1985-01-01

    In somatic cells of Drosophila, the ratio of X chromosomes to autosomes (X:A ratio) determines sex and dosage compensation. The present paper addresses the question of whether germ cells also use the X:A ratio for sex determination and dosage compensation. Triploid female embryos were generated which, through the loss of an unstable ring-X chromosome, contained some germ cells of 2X;3A constitution in their ovaries. Such germ cells were shown to differentiate along one of two alternative pat...

  7. A father effect explains sex-ratio bias.

    Science.gov (United States)

    Malo, Aurelio F; Martinez-Pastor, Felipe; Garcia-Gonzalez, Francisco; Garde, Julián; Ballou, Jonathan D; Lacy, Robert C

    2017-08-30

    Sex ratio allocation has important fitness consequences, and theory predicts that parents should adjust offspring sex ratio in cases where the fitness returns of producing male and female offspring vary. The ability of fathers to bias offspring sex ratios has traditionally been dismissed given the expectation of an equal proportion of X- and Y-chromosome-bearing sperm (CBS) in ejaculates due to segregation of sex chromosomes at meiosis. This expectation has been recently refuted. Here we used Peromyscus leucopus to demonstrate that sex ratio is explained by an exclusive effect of the father, and suggest a likely mechanism by which male-driven sex-ratio bias is attained. We identified a male sperm morphological marker that is associated with the mechanism leading to sex ratio bias; differences among males in the sperm nucleus area (a proxy for the sex chromosome that the sperm contains) explain 22% variation in litter sex ratio. We further show the role played by the sperm nucleus area as a mediator in the relationship between individual genetic variation and sex-ratio bias. Fathers with high levels of genetic variation had ejaculates with a higher proportion of sperm with small nuclei area. This, in turn, led to siring a higher proportion of sons (25% increase in sons per 0.1 decrease in the inbreeding coefficient). Our results reveal a plausible mechanism underlying unexplored male-driven sex-ratio biases. We also discuss why this pattern of paternal bias can be adaptive. This research puts to rest the idea that father contribution to sex ratio variation should be disregarded in vertebrates, and will stimulate research on evolutionary constraints to sex ratios-for example, whether fathers and mothers have divergent, coinciding, or neutral sex allocation interests. Finally, these results offer a potential explanation for those intriguing cases in which there are sex ratio biases, such as in humans. © 2017 The Author(s).

  8. Sex-chromosome anaphase movements in crane-fly spermatocytes are coordinated: ultraviolet microbeam irradiation of one kinetochore of one sex chromosome blocks the movements of both sex chromosomes

    International Nuclear Information System (INIS)

    Swedak, J.A.M.; Forer, A.

    1987-01-01

    Sex chromosomes in crane-fly spermatocytes move polewards at anaphase after the autosomes have reached the poles. We irradiated one kinetochore of one sex chromosome using an ultraviolet microbeam. When both sex chromosomes were normally oriented, irradiation of a single kinetochore permanently blocked movement of both sex chromosomes. Irradiation of non-kinetochore chromosomal regions or of spindle fibres did not block movement, or blocked movement only temporarily. We argue that ultraviolet irradiation of one kinetochore blocks movement of both sex chromosomes because of effects on a 'signal' system. Irradiation of one kinetochore of a maloriented sex chromosome did not block motion of either sex chromosome. However, irradiation of one kinetochore of a normally oriented sex chromosome permanently blocked motion of both that sex chromosome and the maloriented sex chromosome. Thus for the signal system to allow the sex chromosomes to move to the pole each sex chromosome must have one spindle fibre to each pole. (author)

  9. Transcriptome profiling of Nasonia vitripennis testis reveals novel transcripts expressed from the selfish B chromosome, paternal sex ratio.

    Science.gov (United States)

    Akbari, Omar S; Antoshechkin, Igor; Hay, Bruce A; Ferree, Patrick M

    2013-09-04

    A widespread phenomenon in nature is sex ratio distortion of arthropod populations caused by microbial and genetic parasites. Currently little is known about how these agents alter host developmental processes to favor one sex or the other. The paternal sex ratio (PSR) chromosome is a nonessential, paternally transmitted centric fragment that segregates in natural populations of the jewel wasp, Nasonia vitripennis. To persist, PSR is thought to modify the hereditary material of the developing sperm, with the result that all nuclear DNA other than the PSR chromosome is destroyed shortly after fertilization. This results in the conversion of a fertilized embryo--normally a female--into a male, thereby insuring transmission of the "selfish" PSR chromosome, and simultaneously leading to wasp populations that are male-biased. To begin to understand this system at the mechanistic level, we carried out transcriptional profiling of testis from WT and PSR-carrying males. We identified a number of transcripts that are differentially expressed between these conditions. We also discovered nine transcripts that are uniquely expressed from the PSR chromosome. Four of these PSR-specific transcripts encode putative proteins, whereas the others have very short open reading frames and no homology to known proteins, suggesting that they are long noncoding RNAs. We propose several different models for how these transcripts could facilitate PSR-dependent effects. Our analyses also revealed 15.71 MB of novel transcribed regions in the N. vitripennis genome, thus increasing the current annotation of total transcribed regions by 53.4%. Finally, we detected expression of multiple meiosis-related genes in the wasp testis, despite the lack of conventional meiosis in the male sex.

  10. Association testing to detect gene-gene interactions on sex chromosomes in trio data

    Directory of Open Access Journals (Sweden)

    Yeonok eLee

    2013-11-01

    Full Text Available Autism Spectrum Disorder (ASD occurs more often among males than females in a 4:1 ratio. Among theories used to explain the causes of ASD, the X chromosome and the Y chromosome theories attribute ASD to X-linked mutation and the male-limited gene expressions on the Y chromosome, respectively. Despite the rationale of the theory, studies have failed to attribute the sex-biased ratio to the significant linkage or association on the regions of interest on X chromosome. We further study the gender biased ratio by examining the possible interaction effects between two genes in the sex chromosomes. We propose a logistic regression model with mixed effects to detect gene-gene interactions on sex chromosomes. We investigated the power and type I error rates of the approach for a range of minor allele frequencies and varying linkage disequilibrium between markers and QTLs. We also evaluated the robustness of the model to population stratification. We applied the model to a trio-family data set with an ASD affected male child to study gene-gene interactions on sex chromosomes.

  11. Impaired imprinted X chromosome inactivation is responsible for the skewed sex ratio following in vitro fertilization

    Science.gov (United States)

    Tan, Kun; An, Lei; Miao, Kai; Ren, Likun; Hou, Zhuocheng; Tao, Li; Zhang, Zhenni; Wang, Xiaodong; Xia, Wei; Liu, Jinghao; Wang, Zhuqing; Xi, Guangyin; Gao, Shuai; Sui, Linlin; Zhu, De-Sheng; Wang, Shumin; Wu, Zhonghong; Bach, Ingolf; Chen, Dong-bao; Tian, Jianhui

    2016-01-01

    Dynamic epigenetic reprogramming occurs during normal embryonic development at the preimplantation stage. Erroneous epigenetic modifications due to environmental perturbations such as manipulation and culture of embryos during in vitro fertilization (IVF) are linked to various short- or long-term consequences. Among these, the skewed sex ratio, an indicator of reproductive hazards, was reported in bovine and porcine embryos and even human IVF newborns. However, since the first case of sex skewing reported in 1991, the underlying mechanisms remain unclear. We reported herein that sex ratio is skewed in mouse IVF offspring, and this was a result of female-biased peri-implantation developmental defects that were originated from impaired imprinted X chromosome inactivation (iXCI) through reduced ring finger protein 12 (Rnf12)/X-inactive specific transcript (Xist) expression. Compensation of impaired iXCI by overexpression of Rnf12 to up-regulate Xist significantly rescued female-biased developmental defects and corrected sex ratio in IVF offspring. Moreover, supplementation of an epigenetic modulator retinoic acid in embryo culture medium up-regulated Rnf12/Xist expression, improved iXCI, and successfully redeemed the skewed sex ratio to nearly 50% in mouse IVF offspring. Thus, our data show that iXCI is one of the major epigenetic barriers for the developmental competence of female embryos during preimplantation stage, and targeting erroneous epigenetic modifications may provide a potential approach for preventing IVF-associated complications. PMID:26951653

  12. Gonadal sex chromosome complement in individuals with sex chromosomal and/or gonadal disorders

    Energy Technology Data Exchange (ETDEWEB)

    Bridge, J.A.; Sanger, W.G.; Seemayer, T. [Univ. of Nebraska Medical Center, Omaha, NE (United States)] [and others

    1994-09-01

    Gonadal abnormalities are characteristically seen in patients with sex chromosomal aneuploidy. Morphologically these abnormalities can be variable and are hypothesized to be dependent on the sex chromosomal consititution of the gonad (independent of the chromosomal complement of other tissues, such as peripheral blood lymphocytes). In this study, the gonadal sex chromosome complement was evaluated for potential mosaicism and correlated with the histopathology from 5 patients with known sex chromosomal and/or gonadal disorders. FISH techniques using X and Y chromosome specific probes were performed on nuclei extracted from paraffin embedded tissue. Gonadal tissue obtained from case 1 (a true hemaphroditic newborn) consisted of ovotestes and epididymis (left side) and ovary with fallopian tube (right side). Cytogenetic and FISH studies performed on blood, ovotestes and ovary revealed an XX complement. Cytogenetic analysis of blood from case 2, a 4-year-old with suspected Turner syndrome revealed 45,X/46,X,del(Y)(q11.21). FISH analysis of the resected gonads (histologically = immature testes) confirmed an X/XY mosaic complement. Histologically, the gonadal tissue was testicular. Severe autolysis prohibited successful analysis in the 2 remaining cases. In summary, molecular cytogenetic evaluation of gonadal tissue from individuals with sex chromosomal and/or gonadal disorders did not reveal tissue-specific anomalies which could account for differences observed pathologically.

  13. Cretaceous park of sex determination: sex chromosomes are conserved across iguanas.

    Science.gov (United States)

    Rovatsos, Michail; Pokorná, Martina; Altmanová, Marie; Kratochvíl, Lukáš

    2014-03-01

    Many poikilothermic vertebrate lineages, especially among amphibians and fishes, possess a rapid turnover of sex chromosomes, while in endotherms there is a notable stability of sex chromosomes. Reptiles in general exhibit variability in sex-determining systems; as typical poikilotherms, they might be expected to have a rapid turnover of sex chromosomes. However, molecular data which would enable the testing of the stability of sex chromosomes are lacking in most lineages. Here, we provide molecular evidence that sex chromosomes are highly conserved across iguanas, one of the most species-rich clade of reptiles. We demonstrate that members of the New World families Iguanidae, Tropiduridae, Leiocephalidae, Phrynosomatidae, Dactyloidae and Crotaphytidae, as well as of the family Opluridae which is restricted to Madagascar, all share homologous sex chromosomes. As our sampling represents the majority of the phylogenetic diversity of iguanas, the origin of iguana sex chromosomes can be traced back in history to the basal splitting of this group which occurred during the Cretaceous period. Iguanas thus show a stability of sex chromosomes comparable to mammals and birds and represent the group with the oldest sex chromosomes currently known among amniotic poikilothermic vertebrates.

  14. Sex Determination, Sex Chromosomes, and Karyotype Evolution in Insects.

    Science.gov (United States)

    Blackmon, Heath; Ross, Laura; Bachtrog, Doris

    2017-01-01

    Insects harbor a tremendous diversity of sex determining mechanisms both within and between groups. For example, in some orders such as Hymenoptera, all members are haplodiploid, whereas Diptera contain species with homomorphic as well as male and female heterogametic sex chromosome systems or paternal genome elimination. We have established a large database on karyotypes and sex chromosomes in insects, containing information on over 13000 species covering 29 orders of insects. This database constitutes a unique starting point to report phylogenetic patterns on the distribution of sex determination mechanisms, sex chromosomes, and karyotypes among insects and allows us to test general theories on the evolutionary dynamics of karyotypes, sex chromosomes, and sex determination systems in a comparative framework. Phylogenetic analysis reveals that male heterogamety is the ancestral mode of sex determination in insects, and transitions to female heterogamety are extremely rare. Many insect orders harbor species with complex sex chromosomes, and gains and losses of the sex-limited chromosome are frequent in some groups. Haplodiploidy originated several times within insects, and parthenogenesis is rare but evolves frequently. Providing a single source to electronically access data previously distributed among more than 500 articles and books will not only accelerate analyses of the assembled data, but also provide a unique resource to guide research on which taxa are likely to be informative to address specific questions, for example, for genome sequencing projects or large-scale comparative studies. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Invited review: sex ratio and rheumatic disease.

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    Lockshin, M D

    2001-11-01

    Human illnesses affect men and women differently. In some cases (diseases of sex organs, diseases resulting from X or Y chromosome mutations), reasons for sex discrepancy are obvious, but in other cases no reason is apparent. Explanations for sex discrepancy of illness occur at different biological levels: molecular (e.g., imprinting, X-inactivation), cellular (sex-specific receptor activity), organ (endocrine influences), whole organism (size, age), and environmental-behavioral, including intrauterine influences. Autoimmunity represents a prototypical class of illness that has high female-to-male (F/M) ratios. Although the F/M ratios in autoimmune diseases are usually attributed to the influence of estrogenic hormones, evidence demonstrates that the attributed ratios are imprecise and that definitions and classifications of autoimmune diseases vary, rendering at least part of the counting imprecise. In addition, many studies on sex discrepancy of human disease fail to distinguish between disease incidence and disease severity. In April 2001, the Institute of Medicine of the National Academy of Sciences published Exploring the Biological Contributions to Human Health: Does Sex Matter? (Wizemann T and Pardue M-L, editors). This minireview summarizes the section of that report that concerns autoimmune and infectious disease. Some thyroid, rheumatic, and hepatic autoimmune diseases have high F/M ratios, whereas others have low. Those that have high ratios occur primarily in young adulthood. Gonadal hormones, if they play a role, likely do so through a threshold or permissive mechanism. Examples of sex differences that could be caused by environmental exposure, X inactivation, imprinting, X or Y chromosome genetic modulators, and intrauterine influences are presented as alternate, theoretical, and largely unexplored explanations for sex differences of incidence. The epidemiology of autoimmune diseases (young, female) suggests that an explanation for sex discrepancy of

  16. Why Do Sex Chromosomes Stop Recombining?

    Science.gov (United States)

    Ponnikas, Suvi; Sigeman, Hanna; Abbott, Jessica K; Hansson, Bengt

    2018-04-28

    It is commonly assumed that sex chromosomes evolve recombination suppression because selection favours linkage between sex-determining and sexually antagonistic genes. However, although the role of sexual antagonism during sex chromosome evolution has attained strong support from theory, experimental and observational evidence is rare or equivocal. Here, we highlight alternative, often neglected, hypotheses for recombination suppression on sex chromosomes, which invoke meiotic drive, heterozygote advantage, and genetic drift, respectively. We contrast the hypotheses, the situations when they are likely to be of importance, and outline why it is surprisingly difficult to test them. Lastly, we discuss future research directions (including modelling, population genomics, comparative approaches, and experiments) to disentangle the different hypotheses of sex chromosome evolution. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. The evolution of sex chromosomes in organisms with separate haploid sexes.

    Science.gov (United States)

    Immler, Simone; Otto, Sarah Perin

    2015-03-01

    The evolution of dimorphic sex chromosomes is driven largely by the evolution of reduced recombination and the subsequent accumulation of deleterious mutations. Although these processes are increasingly well understood in diploid organisms, the evolution of dimorphic sex chromosomes in haploid organisms (U/V) has been virtually unstudied theoretically. We analyze a model to investigate the evolution of linkage between fitness loci and the sex-determining region in U/V species. In a second step, we test how prone nonrecombining regions are to degeneration due to accumulation of deleterious mutations. Our modeling predicts that the decay of recombination on the sex chromosomes and the addition of strata via fusions will be just as much a part of the evolution of haploid sex chromosomes as in diploid sex chromosome systems. Reduced recombination is broadly favored, as long as there is some fitness difference between haploid males and females. The degeneration of the sex-determining region due to the accumulation of deleterious mutations is expected to be slower in haploid organisms because of the absence of masking. Nevertheless, balancing selection often drives greater differentiation between the U/V sex chromosomes than in X/Y and Z/W systems. We summarize empirical evidence for haploid sex chromosome evolution and discuss our predictions in light of these findings. © 2015 The Author(s).

  18. Sex determination in Madagascar geckos of the genus Paroedura (Squamata: Gekkonidae): are differentiated sex chromosomes indeed so evolutionary stable?

    Science.gov (United States)

    Koubová, Martina; Johnson Pokorná, Martina; Rovatsos, Michail; Farkačová, Klára; Altmanová, Marie; Kratochvíl, Lukáš

    2014-12-01

    Among amniote vertebrates, geckos represent a clade with exceptional variability in sex determination; however, only a minority of species of this highly diverse group has been studied in this respect. Here, we describe for the first time a female heterogamety in the genus Paroedura, the group radiated in Madagascar and adjacent islands. We identified homomorphic ZZ/ZW sex chromosomes with a highly heterochromatic W chromosome in Paroedura masobe, Paroedura oviceps, Paroedura karstophila, Paroedura stumpffi, and Paroedura lohatsara. Comparative genomic hybridization (CGH) revealed that female-specific sequences are greatly amplified in the W chromosome of P. lohatsara and that P. gracilis seems to possess a derived system of multiple sex chromosomes. Contrastingly, neither CGH nor heterochromatin visualization revealed differentiated sex chromosomes in the members of the Paroedura picta-Paroedura bastardi-Paroedura ibityensis clade, which is phylogenetically nested within lineages with a heterochromatic W chromosome. As a sex ratio consistent with genotypic sex determination has been reported in P. picta, it appears that the members of the P. picta-P. bastardi-P. ibityensis clade possess homomorphic, poorly differentiated sex chromosomes and may represent a rare example of evolutionary loss of highly differentiated sex chromosomes. Fluorescent in situ hybridization (FISH) with a telomeric probe revealed a telomere-typical pattern in all species and an accumulation of telomeric sequences in the centromeric region of autosomes in P. stumpffi and P. bastardi. Our study adds important information for the greater understanding of the variability and evolution of sex determination in geckos and demonstrates how the geckos of the genus Paroedura provide an interesting model for studying the evolution of the sex chromosomes.

  19. Chromosome Banding in Amphibia. XXXVI. Multimorphic Sex Chromosomes and an Enigmatic Sex Determination in Eleutherodactylus johnstonei (Anura, Eleutherodactylidae).

    Science.gov (United States)

    Schmid, Michael; Steinlein, Claus

    2018-01-01

    A detailed cytogenetic study on the leaf litter frog Eleutherodactylus johnstonei from 14 different Caribbean islands and the mainlands of Venezuela and Guyana revealed the existence of multimorphic XY♂/XX♀ sex chromosomes 14. Their male sex determination and development depends either on the presence of 2 telocentric chromosomes 14 (XtYt), or on 1 submetacentric chromosome 14 (Xsm) plus 1 telocentric chromosome 14 (Yt), or on the presence of 2 submetacentric chromosomes 14 (XsmYsm). The female sex determination and development requires either the presence of 2 telocentric chromosomes 14 (XtXt) or 2 submetacentric chromosomes 14 (XsmXsm). In all individuals analyzed, the sex chromosomes 14 carry a prominent nucleolus organizer region in their long arms. An explanation is given for the origin of the (XtYt)♂, (XsmYt)♂, (XsmYsm)♂, (XtXt)♀, and (XsmXsm)♀ in the different populations of E. johnstonei. Furthermore, the present study gives detailed data on the chromosome banding patterns, in situ hybridization experiments, and the genome size of E. johnstonei. © 2018 S. Karger AG, Basel.

  20. On the origin of sex chromosomes from meiotic drive

    Science.gov (United States)

    Úbeda, Francisco; Patten, Manus M.; Wild, Geoff

    2015-01-01

    Most animals and many plants make use of specialized chromosomes (sex chromosomes) to determine an individual's sex. Best known are the XY and ZW sex-determination systems. Despite having evolved numerous times, sex chromosomes present something of an evolutionary puzzle. At their origin, alleles that dictate development as one sex or the other (primitive sex chromosomes) face a selective penalty, as they will be found more often in the more abundant sex. How is it possible that primitive sex chromosomes overcome this disadvantage? Any theory for the origin of sex chromosomes must identify the benefit that outweighs this cost and enables a sex-determining mutation to establish in the population. Here we show that a new sex-determining allele succeeds when linked to a sex-specific meiotic driver. The new sex-determining allele benefits from confining the driving allele to the sex in which it gains the benefit of drive. Our model requires few special assumptions and is sufficiently general to apply to the evolution of sex chromosomes in outbreeding cosexual or dioecious species. We highlight predictions of the model that can discriminate between this and previous theories of sex-chromosome origins. PMID:25392470

  1. Conserved sex chromosomes across adaptively radiated Anolis lizards.

    Science.gov (United States)

    Rovatsos, Michail; Altmanová, Marie; Pokorná, Martina; Kratochvíl, Lukáš

    2014-07-01

    Vertebrates possess diverse sex-determining systems, which differ in evolutionary stability among particular groups. It has been suggested that poikilotherms possess more frequent turnovers of sex chromosomes than homoiotherms, whose effective thermoregulation can prevent the emergence of the sex reversals induced by environmental temperature. Squamate reptiles used to be regarded as a group with an extensive variability in sex determination; however, we document how the rather old radiation of lizards from the genus Anolis, known for exceptional ecomorphological variability, was connected with stability in sex chromosomes. We found that 18 tested species, representing most of the phylogenetic diversity of the genus, share the gene content of their X chromosomes. Furthermore, we discovered homologous sex chromosomes in species of two genera (Sceloporus and Petrosaurus) from the family Phrynosomatidae, serving here as an outgroup to Anolis. We can conclude that the origin of sex chromosomes within iguanas largely predates the Anolis radiation and that the sex chromosomes of iguanas remained conserved for a significant part of their evolutionary history. Next to therian mammals and birds, Anolis lizards therefore represent another adaptively radiated amniote clade with conserved sex chromosomes. We argue that the evolutionary stability of sex-determining systems may reflect an advanced stage of differentiation of sex chromosomes rather than thermoregulation strategy. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  2. Differentiation of sex chromosomes and karyotypic evolution in the eye-lid geckos (Squamata: Gekkota: Eublepharidae), a group with different modes of sex determination.

    Science.gov (United States)

    Pokorná, Martina; Rábová, Marie; Ráb, Petr; Ferguson-Smith, Malcolm A; Rens, Willem; Kratochvíl, Lukáš

    2010-11-01

    The eyelid geckos (family Eublepharidae) include both species with temperature-dependent sex determination and species where genotypic sex determination (GSD) was suggested based on the observation of equal sex ratios at several incubation temperatures. In this study, we present data on karyotypes and chromosomal characteristics in 12 species (Aeluroscalabotes felinus, Coleonyx brevis, Coleonyx elegans, Coleonyx variegatus, Eublepharis angramainyu, Eublepharis macularius, Goniurosaurus araneus, Goniurosaurus lichtenfelderi, Goniurosaurus luii, Goniurosaurus splendens, Hemitheconyx caudicinctus, and Holodactylus africanus) covering all genera of the family, and search for the presence of heteromorphic sex chromosomes. Phylogenetic mapping of chromosomal changes showed a long evolutionary stasis of karyotypes with all acrocentric chromosomes followed by numerous chromosomal rearrangements in the ancestors of two lineages. We have found heteromorphic sex chromosomes in only one species, which suggests that sex chromosomes in most GSD species of the eyelid geckos are not morphologically differentiated. The sexual difference in karyotype was detected only in C. elegans which has a multiple sex chromosome system (X(1)X(2)Y). The metacentric Y chromosome evolved most likely via centric fusion of two acrocentric chromosomes involving loss of interstitial telomeric sequences. We conclude that the eyelid geckos exhibit diversity in sex determination ranging from the absence of any sexual differences to heteromorphic sex chromosomes, which makes them an interesting system for exploring the evolutionary origin of sexually dimorphic genomes.

  3. B chromosomes have a functional effect on female sex determination in Lake Victoria cichlid fishes.

    Directory of Open Access Journals (Sweden)

    Kohta Yoshida

    2011-08-01

    Full Text Available The endemic cichlid fishes in Lake Victoria are a model system for speciation through adaptive radiation. Although the evolution of the sex-determination system may also play a role in speciation, little is known about the sex-determination system of Lake Victoria cichlids. To understand the evolution of the sex-determination system in these fish, we performed cytogenetic analysis in 11 cichlid species from Lake Victoria. B chromosomes, which are present in addition to standard chromosomes, were found at a high prevalence rate (85% in these cichlids. In one species, B chromosomes were female-specific. Cross-breeding using females with and without the B chromosomes demonstrated that the presence of the B chromosomes leads to a female-biased sex ratio in this species. Although B chromosomes were believed to be selfish genetic elements with little effect on phenotype and to lack protein-coding genes, the present study provides evidence that B chromosomes have a functional effect on female sex determination. FISH analysis using a BAC clone containing B chromosome DNA suggested that the B chromosomes are derived from sex chromosomes. Determination of the nucleotide sequences of this clone (104.5 kb revealed the presence of several protein-coding genes in the B chromosome, suggesting that B chromosomes have the potential to contain functional genes. Because some sex chromosomes in amphibians and arthropods are thought to be derived from B chromosomes, the B chromosomes in Lake Victoria cichlids may represent an evolutionary transition toward the generation of sex chromosomes.

  4. Evolutionary stability of sex chromosomes in snakes.

    Science.gov (United States)

    Rovatsos, Michail; Vukić, Jasna; Lymberakis, Petros; Kratochvíl, Lukáš

    2015-12-22

    Amniote vertebrates possess various mechanisms of sex determination, but their variability is not equally distributed. The large evolutionary stability of sex chromosomes in viviparous mammals and birds was believed to be connected with their endothermy. However, some ectotherm lineages seem to be comparably conserved in sex determination, but previously there was a lack of molecular evidence to confirm this. Here, we document a stability of sex chromosomes in advanced snakes based on the testing of Z-specificity of genes using quantitative PCR (qPCR) across 37 snake species (our qPCR technique is suitable for molecular sexing in potentially all advanced snakes). We discovered that at least part of sex chromosomes is homologous across all families of caenophidian snakes (Acrochordidae, Xenodermatidae, Pareatidae, Viperidae, Homalopsidae, Colubridae, Elapidae and Lamprophiidae). The emergence of differentiated sex chromosomes can be dated back to about 60 Ma and preceded the extensive diversification of advanced snakes, the group with more than 3000 species. The Z-specific genes of caenophidian snakes are (pseudo)autosomal in the members of the snake families Pythonidae, Xenopeltidae, Boidae, Erycidae and Sanziniidae, as well as in outgroups with differentiated sex chromosomes such as monitor lizards, iguanas and chameleons. Along with iguanas, advanced snakes are therefore another example of ectothermic amniotes with a long-term stability of sex chromosomes comparable with endotherms. © 2015 The Author(s).

  5. Genetics of dioecy and causal sex chromosomes in plants

    Indian Academy of Sciences (India)

    2014-04-15

    chromosome evolution; sex-ratio variation ...... interaction between the two genes, Cm ACS7 and Cm W1P1, ... son of low pollinator density seed formation will be scanty ...... Kaltz O. and Bell G. 2002 The ecology and genetics of fitness in.

  6. Y Fuse? Sex Chromosome Fusions in Fishes and Reptiles

    Science.gov (United States)

    Vamosi, Jana C.; Peichel, Catherine L.; Valenzuela, Nicole; Kitano, Jun

    2015-01-01

    Chromosomal fusion plays a recurring role in the evolution of adaptations and reproductive isolation among species, yet little is known of the evolutionary drivers of chromosomal fusions. Because sex chromosomes (X and Y in male heterogametic systems, Z and W in female heterogametic systems) differ in their selective, mutational, and demographic environments, those differences provide a unique opportunity to dissect the evolutionary forces that drive chromosomal fusions. We estimate the rate at which fusions between sex chromosomes and autosomes become established across the phylogenies of both fishes and squamate reptiles. Both the incidence among extant species and the establishment rate of Y-autosome fusions is much higher than for X-autosome, Z-autosome, or W-autosome fusions. Using population genetic models, we show that this pattern cannot be reconciled with many standard explanations for the spread of fusions. In particular, direct selection acting on fusions or sexually antagonistic selection cannot, on their own, account for the predominance of Y-autosome fusions. The most plausible explanation for the observed data seems to be (a) that fusions are slightly deleterious, and (b) that the mutation rate is male-biased or the reproductive sex ratio is female-biased. We identify other combinations of evolutionary forces that might in principle account for the data although they appear less likely. Our results shed light on the processes that drive structural changes throughout the genome. PMID:25993542

  7. High degree of sex chromosome differentiation in stickleback fishes

    Directory of Open Access Journals (Sweden)

    Shimada Yukinori

    2011-09-01

    Full Text Available Abstract Background Studies of closely related species with different sex chromosome systems can provide insights into the processes of sex chromosome differentiation and evolution. To investigate the potential utility of molecular markers in studying sex chromosome differentiation at early stages of their divergence, we examined the levels and patterns of genetic differentiation between sex chromosomes in nine-spined (Pungitius pungitius and three-spined sticklebacks (Gasterosteus aculeatus using microsatellite markers. Results A set of novel microsatellite markers spanning the entire length of the sex chromosomes were developed for nine-spined sticklebacks using the sequenced genomes of other fish species. Sex-specific patterns of genetic variability and male-specific alleles were identified at most of these loci, indicating a high degree of differentiation between the X and Y chromosomes in nine-spined sticklebacks. In three-spined sticklebacks, male-specific alleles were detected at some loci confined to two chromosomal regions. In addition, male-specific null alleles were identified at several other loci, implying the absence of Y chromosomal alleles at these loci. Overall, male-specific alleles and null alleles were found over a region spanning 81% of the sex chromosomes in three-spined sticklebacks. Conclusions High levels but distinct patterns of sex chromosome differentiation were uncovered in the stickleback species that diverged 13 million years ago. Our results suggest that the Y chromosome is highly degenerate in three-spined sticklebacks, but not in nine-spined sticklebacks. In general, the results demonstrate that microsatellites can be useful in identifying the degree and patterns of sex chromosome differentiation in species at initial stages of sex chromosome evolution.

  8. Allele-specific marker generation and linkage mapping on the Xiphophorus sex chromosomes.

    Science.gov (United States)

    Woolcock, B; Kazianis, S; Lucito, R; Walter, R B; Kallman, K D; Morizot, D C; Vielkind, J R

    2006-01-01

    There is great interest in the sex chromosomes of Xiphophorus fishes because both WY/YY and XX/XY sex-determining mechanisms function in these species, with at least one taxon possessing all three types of sex chromosomes, and because in certain interspecific hybrids melanoma arises as a consequence of inheritance of the sex-linked macromelanophore determining locus (MDL). Representational difference analysis (RDA) has been used to clone two sequences from the sex-determining region of X. maculatus, including a cholinergic receptor, nicotinic, delta polypeptide (CHRND) orthologue. Allele-specific assays for these sequences, as well as for the sex-linked XMRK1 and XMRK2 genes, were developed to distinguish W, X, and Y chromosomes derived from a X. maculatus (XX/XY) strain and a X. helleri (WY/YY) strain. Linkage mapping localized these markers to linkage group (LG) 24. No recombinants were observed between XMRK2 and MDL, confirming a role for XMRK2 in macromelanophore development. Although the master sex-determining (SD) locus certainly resides on Xiphophorus LG 24, autosomal loci are probably involved in sex determination as well, as indicated by the abnormal sex ratios in the backcross hybrids that contrast theoretical predictions based on LG 24 genotyping. Marker development and allelic discrimination on the Xiphophorus sex chromosomes should prove highly useful for studies that utilize this genus as an animal model.

  9. Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

    Science.gov (United States)

    Gleeson, Dianne; Georges, Arthur

    2018-01-01

    Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata) which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways. PMID:29751579

  10. Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

    Directory of Open Access Journals (Sweden)

    Shayer Mahmood Ibney Alam

    2018-05-01

    Full Text Available Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD and temperature-dependent sex determination (TSD within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways.

  11. Temporal genomic evolution of bird sex chromosomes

    DEFF Research Database (Denmark)

    Wang, Zongji; Zhang, Jilin; Yang, Wei

    2014-01-01

    BACKGROUND: Sex chromosomes exhibit many unusual patterns in sequence and gene expression relative to autosomes. Birds have evolved a female heterogametic sex system (male ZZ, female ZW), through stepwise suppression of recombination between chrZ and chrW. To address the broad patterns and complex...... driving forces of Z chromosome evolution, we analyze here 45 newly available bird genomes and four species' transcriptomes, over their course of recombination loss between the sex chromosomes. RESULTS: We show Z chromosomes in general have a significantly higher substitution rate in introns and synonymous...... ('fast-Z' evolution). And species with a lower level of intronic heterozygosities tend to evolve even faster on the Z chromosome. Further analysis of fast-evolving genes' enriched functional categories and sex-biased expression patterns support that, fast-Z evolution in birds is mainly driven by genetic...

  12. Sex chromosome complement influences operant responding for a palatable food in mice.

    Science.gov (United States)

    Seu, Emanuele; Groman, Stephanie M; Arnold, Arthur P; Jentsch, J David

    2014-07-01

    The procurement and consumption of palatable, calorie-dense foods is influenced by the nutritional and hedonic value of foods. Although many factors can influence the control over behavior by foods rich in sugar and fat, emerging evidence indicates that biological sex may play a particularly crucial role in the types of foods individuals seek out, as well as the level of motivation individuals will exert to obtain those foods. However, a systematic investigation of food-seeking and consumption that disentangles the effects of the major sex-biasing factors, including sex chromosome complement and organizational and activational effects of sex hormones, has yet to be conducted. Using the four core genotypes mouse model system, we separated and quantified the effects of sex chromosome complement and gonadal sex on consumption of and motivation to obtain a highly palatable solution [sweetened condensed milk (SCM)]. Gonadectomized mice with an XY sex chromosome complement, compared with those with two X chromosomes, independent of gonadal sex, appeared to be more sensitive to the reward value of the SCM solution and were more motivated to expend effort to obtain it, as evidenced by their dramatically greater expended effort in an instrumental task with progressively larger response-to-reward ratios. Gonadal sex independently affected free consumption of the solution but not motivation to obtain it. These data indicate that gonadal and chromosomal sex effects independently influence reward-related behaviors, contributing to sexually dimorphic patterns of behavior related to the pursuit and consumption of rewards. © 2014 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  13. Turnover of sex chromosomes in the stickleback fishes (gasterosteidae.

    Directory of Open Access Journals (Sweden)

    Joseph A Ross

    2009-02-01

    Full Text Available Diverse sex-chromosome systems are found in vertebrates, particularly in teleost fishes, where different systems can be found in closely related species. Several mechanisms have been proposed for the rapid turnover of sex chromosomes, including the transposition of an existing sex-determination gene, the appearance of a new sex-determination gene on an autosome, and fusions between sex chromosomes and autosomes. To better understand these evolutionary transitions, a detailed comparison of sex chromosomes between closely related species is essential. Here, we used genetic mapping and molecular cytogenetics to characterize the sex-chromosome systems of multiple stickleback species (Gasterosteidae. Previously, we demonstrated that male threespine stickleback fish (Gasterosteus aculeatus have a heteromorphic XY pair corresponding to linkage group (LG 19. In this study, we found that the ninespine stickleback (Pungitius pungitius has a heteromorphic XY pair corresponding to LG12. In black-spotted stickleback (G. wheatlandi males, one copy of LG12 has fused to the LG19-derived Y chromosome, giving rise to an X(1X(2Y sex-determination system. In contrast, neither LG12 nor LG19 is linked to sex in two other species: the brook stickleback (Culaea inconstans and the fourspine stickleback (Apeltes quadracus. However, we confirmed the existence of a previously reported heteromorphic ZW sex-chromosome pair in the fourspine stickleback. The sex-chromosome diversity that we have uncovered in sticklebacks provides a rich comparative resource for understanding the mechanisms that underlie the rapid turnover of sex-chromosome systems.

  14. Abnormal sex chromosome constitution and longitudinal growth

    DEFF Research Database (Denmark)

    Aksglaede, Lise; Skakkebaek, Niels E; Juul, Anders

    2008-01-01

    Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles.......Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles....

  15. Postzygotic isolation involves strong mitochondrial and sex-specific effects in Tigriopus californicus, a species lacking heteromorphic sex chromosomes.

    Science.gov (United States)

    Foley, B R; Rose, C G; Rundle, D E; Leong, W; Edmands, S

    2013-11-01

    Detailed studies of the genetics of speciation have focused on a few model systems, particularly Drosophila. The copepod Tigriopus californicus offers an alternative that differs from standard animal models in that it lacks heteromorphic chromosomes (instead, sex determination is polygenic) and has reduced opportunities for sexual conflict, because females mate only once. Quantitative trait loci (QTL) mapping was conducted on reciprocal F2 hybrids between two strongly differentiated populations, using a saturated linkage map spanning all 12 autosomes and the mitochondrion. By comparing sexes, a possible sex ratio distorter was found but no sex chromosomes. Although studies of standard models often find an excess of hybrid male sterility factors, we found no QTL for sterility and multiple QTL for hybrid viability (indicated by non-Mendelian adult ratios) and other characters. Viability problems were found to be stronger in males, but the usual explanations for weaker hybrid males (sex chromosomes, sensitivity of spermatogenesis, sexual selection) cannot fully account for these male viability problems. Instead, higher metabolic rates may amplify deleterious effects in males. Although many studies of standard speciation models find the strongest genetic incompatibilities to be nuclear-nuclear (specifically X chromosome-autosome), we found the strongest deleterious interaction in this system was mito-nuclear. Consistent with the snowball theory of incompatibility accumulation, we found that trigenic interactions in this highly divergent cross were substantially more frequent (>6×) than digenic interactions. This alternative system thus allows important comparisons to studies of the genetics of reproductive isolation in more standard model systems.

  16. Exposure to widespread environmental endocrine disrupting chemicals and human sperm sex ratio

    International Nuclear Information System (INIS)

    Jurewicz, Joanna; Radwan, Michał; Sobala, Wojciech; Radwan, Paweł; Jakubowski, Lucjusz; Wielgomas, Bartosz; Ligocka, Danuta; Brzeźnicki, Sławomir; Hanke, Wojciech

    2016-01-01

    In recent years, a trend toward a declining proportion of male births has been noted in several, but not all, industrialized countries. The underlying reason for the drop in the sex ratio is unclear, but one theory states that widespread environmental endocrine disrupting chemicals affecting the male reproductive system in a negative manner could be part of the explanation. The present study was designed to investigate whether the urinary phthalate, pyrethroids and polycyclic aromatic hydrocarbons metabolites concentrations were associated with sperm Y:X ratio. The study population consisted of 194 men aged under 45 years of age who attended infertility clinic in Lodz, Poland for diagnostic purposes with normal semen concentration of 20–300 mln/ml or with slight oligozoospermia (semen concentration of 15–20 mln/ml) (WHO, 1999). The Y:X ratio was assessed by fluorescent in situ hybridization. Urinary concentrations of 1-hydroxypyrene were measured by high performance liquid chromatography, phthalate metabolites were analyzed using a procedure based on the LC-MS/MS methods and metabolites of synthetic pyrethroids were assessed by gas chromatography ion-tap mass spectrometry method. After adjustment for potential confounders (past diseases, age, abstinence, smoking, alcohol consumption, sperm concentration, motility, morphology) 5OH MEHP, CDCCA to TDCCA and 1-OHP was negatively related to Y:X sperm chromosome ratio (p = 0.033, p < 0.001, p = 0.047 respectively). As this is the first study to elucidate the association between the level of metabolites of widespread environmental endocrine disrupting chemicals (phthalates, synthetic pyrethroids, polycyclic aromatic hydrocarbons) on sex chromosome ratio in sperm therefore, these findings require further replication in other populations. - Highlights: • Urinary phthalate metabolites levels were significantly associated with a decrease in Y/X chromosome bearing sperm. • The levels of 1-hydroxypyrene in urine

  17. Evolution of heteromorphic sex chromosomes in the order Aulopiformes.

    Science.gov (United States)

    Ota, K; Kobayashi, T; Ueno, K; Gojobori, T

    2000-12-23

    The fish order Aulopiformes contains both synchronously hermaphroditic and gonochoristic species. From the cytogenetic viewpoint, few reports show that gonochoristic Aulopiformes have heteromorphic sex chromosomes. Because fish in this order give us a unique opportunity to elucidate the evolution of sex chromosomes, it is important to examine a phylogenetic relationship in Aulopiformes by both molecular evolutionary and cytogenetic methods. Thus, we conducted molecular phylogenetic and cytogenetic studies of six Aulopiform species. Our results suggested that hermaphroditic species were evolutionarily derived from gonochoristic species. It follows that the hermaphroditic species might have lost the heteromorphic sex chromosomes during evolution. Here, we suggest a possibility that heteromorphic sex chromosomes can disappear from the genome, even if they have appeared once in evolution. Taking into account Ohno's hypothesis that heteromorphic sex chromosomes might have emerged from autosomes, we propose the hypothesis that heteromorphic sex chromosomes may have undergone repeated events of appearance and disappearance during the course of fish evolution.

  18. Sex chromosomes in Ephestia kuehniella

    Czech Academy of Sciences Publication Activity Database

    Marec, František; Sahara, K.; Traut, W.

    2001-01-01

    Roč. 44, č. 1 (2001), s. 131 ISSN 0003-3995. [European Cytogenetics Conference /3./. 07.07.2001-10.07.2001, Paris] Institutional research plan: CEZ:AV0Z5007907 Keywords : Telomere * sex chromosomes * chromosome fragments Subject RIV: EB - Genetics ; Molecular Biology

  19. No evidence for selective follicle abortion underlying primary sex ratio adjustment in pigeons

    NARCIS (Netherlands)

    Goerlich, Vivian C.; Dijkstra, Cornelis; Groothuis, Antonius

    Primary sex ratio adjustment in birds has been extensively studied, yet the underlying physiological mechanisms are far from understood. Avian females are the heterogametic sex (ZW), and the future sex of the offspring is determined at chromosome segregation during meiosis I, shortly before the

  20. Heteromorphic Sex Chromosomes: Navigating Meiosis without a Homologous Partner

    OpenAIRE

    Checchi, Paula M.; Engebrecht, JoAnne

    2011-01-01

    Accurate chromosome segregation during meiosis relies on homology between the maternal and paternal chromosomes. Yet by definition, sex chromosomes of the heterogametic sex lack a homologous partner. Recent studies in a number of systems have shed light on the unique meiotic behavior of heteromorphic sex chromosomes, and highlight both the commonalities and differences in divergent species. During meiotic prophase, the homology-dependent processes of pairing, synapsis, and recombination have ...

  1. A role for a neo-sex chromosome in stickleback speciation

    Science.gov (United States)

    Kitano, Jun; Ross, Joseph A.; Mori, Seiichi; Kume, Manabu; Jones, Felicity C.; Chan, Yingguang F.; Absher, Devin M.; Grimwood, Jane; Schmutz, Jeremy; Myers, Richard M.; Kingsley, David M.; Peichel, Catherine L.

    2009-01-01

    Sexual antagonism, or conflict between the sexes, has been proposed as a driving force in both sex chromosome turnover and speciation. Although closely related species often have different sex chromosome systems, it is unknown whether sex chromosome turnover contributes to the evolution of reproductive isolation between species. In this study, we show that a newly evolved sex chromosome harbours genes that contribute to speciation in threespine stickleback fish (Gasterosteus aculeatus). We first identified a neo-sex chromosome system found only in one member of a sympatric species pair in Japan. We then performed genetic linkage mapping of male-specific traits important for reproductive isolation between the Japanese species pair. The neo-X chromosome harbours loci for male courtship display traits that contribute to behavioural isolation, while the ancestral X chromosome contains loci for both behavioural isolation and hybrid male sterility. Our work not only provides strong evidence for a large-X effect on reproductive isolation in a vertebrate system, but also provides direct evidence that a young neo-X chromosome contributes to reproductive isolation between closely related species. Our data suggest that sex chromosome turnover might play a greater role in speciation than previously appreciated. PMID:19783981

  2. New Y chromosomes and early stages of sex chromosome ...

    Indian Academy of Sciences (India)

    2010-09-06

    Sep 6, 2010 ... chromosomes are evolutionary consequences of that func- tion. Given sufficient ... (for a review, see Charlesworth et al. 2005). ... In the present paper, I review sex deter- mination .... part had apparently been exchanged against the homologous ... age group III-Y chromosomes were successful while in well-.

  3. Evolution of vertebrate sex chromosomes and dosage compensation.

    Science.gov (United States)

    Graves, Jennifer A Marshall

    2016-01-01

    Differentiated sex chromosomes in mammals and other vertebrates evolved independently but in strikingly similar ways. Vertebrates with differentiated sex chromosomes share the problems of the unequal expression of the genes borne on sex chromosomes, both between the sexes and with respect to autosomes. Dosage compensation of genes on sex chromosomes is surprisingly variable - and can even be absent - in different vertebrate groups. Systems that compensate for different gene dosages include a wide range of global, regional and gene-by-gene processes that differ in their extent and their molecular mechanisms. However, many elements of these control systems are similar across distant phylogenetic divisions and show parallels to other gene silencing systems. These dosage systems cannot be identical by descent but were probably constructed from elements of ancient silencing mechanisms that are ubiquitous among vertebrates and shared throughout eukaryotes.

  4. The variability is in the sex chromosomes.

    Science.gov (United States)

    Reinhold, Klaus; Engqvist, Leif

    2013-12-01

    Sex differences in the mean trait expression are well documented, not only for traits that are directly associated with reproduction. Less is known about how the variability of traits differs between males and females. In species with sex chromosomes and dosage compensation, the heterogametic sex is expected to show larger trait variability ("sex-chromosome hypothesis"), yet this central prediction, based on fundamental genetic principles, has never been evaluated in detail. Here we show that in species with heterogametic males, male variability in body size is significantly larger than in females, whereas the opposite can be shown for species with heterogametic females. These results support the prediction of the sex-chromosome hypothesis that individuals of the heterogametic sex should be more variable. We argue that the pattern demonstrated here for sex-specific body size variability is likely to apply to any trait and needs to be considered when testing predictions about sex-specific variability and sexual selection. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  5. Sex Chromosome Translocations in the Evolution of Reproductive Isolation

    Science.gov (United States)

    Tracey, Martin L.

    1972-01-01

    Haldane's rule states that in organisms with differentiated sex chromosomes, hybrid sterility or inviability is generally expressed more frequently in the heterogametic sex. This observation has been variously explained as due to either genic or chromosomal imbalance. The fixation probabilities and mean times to fixation of sex-chromosome translocations of the type necessary to explain Haldane's rule on the basis of chromosomal imbalance have been estimated in small populations of Drosophila melanogaster. The fixation probability of an X chromosome carrying the long arm of the Y(X·YL) is approximately 30% greater than expected under the assumption of no selection. No fitness differences associated with the attached YL segment were detected. The fixation probability of a deficient Y chromosome is 300% greater than expected when the X chromosome contains the deleted portion of the Y. It is suggested that sex-chromosome translocations may play a role in the establishment of reproductive isolation. PMID:4630586

  6. Avian sex, sex chromosomes, and dosage compensation in the age of genomics.

    Science.gov (United States)

    Graves, Jennifer A Marshall

    2014-04-01

    Comparisons of the sex chromosome systems in birds and mammals are widening our view and deepening our understanding of vertebrate sex chromosome organization, function, and evolution. Birds have a very conserved ZW system of sex determination in which males have two copies of a large, gene-rich Z chromosome, and females have a single Z and a female-specific W chromosome. The avian ZW system is quite the reverse of the well-studied mammalian XY chromosome system, and evolved independently from different autosomal blocs. Despite the different gene content of mammal and bird sex chromosomes, there are many parallels. Genes on the bird Z and the mammal X have both undergone selection for male-advantage functions, and there has been amplification of male-advantage genes and accumulation of LINEs. The bird W and mammal Y have both undergone extensive degradation, but some birds retain early stages and some mammals terminal stages of the process, suggesting that the process is more advanced in mammals. Different sex-determining genes, DMRT1 and SRY, define the ZW and XY systems, but DMRT1 is involved in downstream events in mammals. Birds show strong cell autonomous specification of somatic sex differences in ZZ and ZW tissue, but there is growing evidence for direct X chromosome effects on sexual phenotype in mammals. Dosage compensation in birds appears to be phenotypically and molecularly quite different from X inactivation, being partial and gene-specific, but both systems use tools from the same molecular toolbox and there are some signs that galliform birds represent an early stage in the evolution of a coordinated system.

  7. Sex chromosomes and speciation in Drosophila

    Science.gov (United States)

    Presgraves, Daven C.

    2010-01-01

    Two empirical rules suggest that sex chromosomes play a special role in speciation. The first is Haldane's rule— the preferential sterility and inviability of species hybrids of the heterogametic (XY) sex. The second is the disproportionately large effect of the X chromosome in genetic analyses of hybrid sterility. Whereas the causes of Haldane's rule are well established, the causes of the ‘large X-effect’ have remained controversial. New genetic analyses in Drosophila confirm that the X is a hotspot for hybrid male sterility factors, providing a proximate explanation for the large X-effect. Several other new findings— on faster X evolution, X chromosome meiotic drive, and the regulation of the X chromosome in the male-germline— provide plausible evolutionary explanations for the large X-effect. PMID:18514967

  8. SEX-DETector: A Probabilistic Approach to Study Sex Chromosomes in Non-Model Organisms

    Science.gov (United States)

    Muyle, Aline; Käfer, Jos; Zemp, Niklaus; Mousset, Sylvain; Picard, Franck; Marais, Gabriel AB

    2016-01-01

    We propose a probabilistic framework to infer autosomal and sex-linked genes from RNA-seq data of a cross for any sex chromosome type (XY, ZW, and UV). Sex chromosomes (especially the non-recombining and repeat-dense Y, W, U, and V) are notoriously difficult to sequence. Strategies have been developed to obtain partially assembled sex chromosome sequences. Most of them remain difficult to apply to numerous non-model organisms, either because they require a reference genome, or because they are designed for evolutionarily old systems. Sequencing a cross (parents and progeny) by RNA-seq to study the segregation of alleles and infer sex-linked genes is a cost-efficient strategy, which also provides expression level estimates. However, the lack of a proper statistical framework has limited a broader application of this approach. Tests on empirical Silene data show that our method identifies 20–35% more sex-linked genes than existing pipelines, while making reliable inferences for downstream analyses. Approximately 12 individuals are needed for optimal results based on simulations. For species with an unknown sex-determination system, the method can assess the presence and type (XY vs. ZW) of sex chromosomes through a model comparison strategy. The method is particularly well optimized for sex chromosomes of young or intermediate age, which are expected in thousands of yet unstudied lineages. Any organisms, including non-model ones for which nothing is known a priori, that can be bred in the lab, are suitable for our method. SEX-DETector and its implementation in a Galaxy workflow are made freely available. PMID:27492231

  9. New insights into sex chromosome evolution in anole lizards (Reptilia, Dactyloidae).

    Science.gov (United States)

    Giovannotti, M; Trifonov, V A; Paoletti, A; Kichigin, I G; O'Brien, P C M; Kasai, F; Giovagnoli, G; Ng, B L; Ruggeri, P; Cerioni, P Nisi; Splendiani, A; Pereira, J C; Olmo, E; Rens, W; Caputo Barucchi, V; Ferguson-Smith, M A

    2017-03-01

    Anoles are a clade of iguanian lizards that underwent an extensive radiation between 125 and 65 million years ago. Their karyotypes show wide variation in diploid number spanning from 26 (Anolis evermanni) to 44 (A. insolitus). This chromosomal variation involves their sex chromosomes, ranging from simple systems (XX/XY), with heterochromosomes represented by either micro- or macrochromosomes, to multiple systems (X 1 X 1 X 2 X 2 /X 1 X 2 Y). Here, for the first time, the homology relationships of sex chromosomes have been investigated in nine anole lizards at the whole chromosome level. Cross-species chromosome painting using sex chromosome paints from A. carolinensis, Ctenonotus pogus and Norops sagrei and gene mapping of X-linked genes demonstrated that the anole ancestral sex chromosome system constituted by microchromosomes is retained in all the species with the ancestral karyotype (2n = 36, 12 macro- and 24 microchromosomes). On the contrary, species with a derived karyotype, namely those belonging to genera Ctenonotus and Norops, show a series of rearrangements (fusions/fissions) involving autosomes/microchromosomes that led to the formation of their current sex chromosome systems. These results demonstrate that different autosomes were involved in translocations with sex chromosomes in closely related lineages of anole lizards and that several sequential microautosome/sex chromosome fusions lead to a remarkable increase in size of Norops sagrei sex chromosomes.

  10. Sex chromosome turnover contributes to genomic divergence between incipient stickleback species.

    Directory of Open Access Journals (Sweden)

    Kohta Yoshida

    2014-03-01

    Full Text Available Sex chromosomes turn over rapidly in some taxonomic groups, where closely related species have different sex chromosomes. Although there are many examples of sex chromosome turnover, we know little about the functional roles of sex chromosome turnover in phenotypic diversification and genomic evolution. The sympatric pair of Japanese threespine stickleback (Gasterosteus aculeatus provides an excellent system to address these questions: the Japan Sea species has a neo-sex chromosome system resulting from a fusion between an ancestral Y chromosome and an autosome, while the sympatric Pacific Ocean species has a simple XY sex chromosome system. Furthermore, previous quantitative trait locus (QTL mapping demonstrated that the Japan Sea neo-X chromosome contributes to phenotypic divergence and reproductive isolation between these sympatric species. To investigate the genomic basis for the accumulation of genes important for speciation on the neo-X chromosome, we conducted whole genome sequencing of males and females of both the Japan Sea and the Pacific Ocean species. No substantial degeneration has yet occurred on the neo-Y chromosome, but the nucleotide sequence of the neo-X and the neo-Y has started to diverge, particularly at regions near the fusion. The neo-sex chromosomes also harbor an excess of genes with sex-biased expression. Furthermore, genes on the neo-X chromosome showed higher non-synonymous substitution rates than autosomal genes in the Japan Sea lineage. Genomic regions of higher sequence divergence between species, genes with divergent expression between species, and QTL for inter-species phenotypic differences were found not only at the regions near the fusion site, but also at other regions along the neo-X chromosome. Neo-sex chromosomes can therefore accumulate substitutions causing species differences even in the absence of substantial neo-Y degeneration.

  11. Sex Ratio Elasticity Influences the Selection of Sex Ratio Strategy

    Science.gov (United States)

    Wang, Yaqiang; Wang, Ruiwu; Li, Yaotang; (Sam) Ma, Zhanshan

    2016-12-01

    There are three sex ratio strategies (SRS) in nature—male-biased sex ratio, female-biased sex ratio and, equal sex ratio. It was R. A. Fisher who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton’s local mate competition (LMC) and Clark’s local resource competition (LRC) separately explained the observed deviations from the seemingly universal 1:1 ratio. However, to the best of our knowledge, there is not yet a unified theory that accounts for the mechanisms of the three SRS. Here, we introduce the price elasticity theory in economics to define sex ratio elasticity (SRE), and present an analytical model that derives three SRSs based on the following assumption: simultaneously existing competitions for both resources A and resources B influence the level of SRE in both sexes differently. Consequently, it is the difference (between two sexes) in the level of their sex ratio elasticity that leads to three different SRS. Our analytical results demonstrate that the elasticity-based model not only reveals a highly plausible mechanism that explains the evolution of SRS in nature, but also offers a novel framework for unifying two major classical theories (i.e., LMC & LRC) in the field of SRS research.

  12. Postzygotic incompatibilities between the pupfishes, Cyprinodon elegans and Cyprinodon variegatus: hybrid male sterility and sex ratio bias.

    Science.gov (United States)

    Tech, C

    2006-11-01

    I examined the intrinsic postzygotic incompatibilities between two pupfishes, Cyprinodon elegans and Cyprinodon variegatus. Laboratory hybridization experiments revealed evidence of strong postzygotic isolation. Male hybrids have very low fertility, and the survival of backcrosses into C. elegans was substantially reduced. In addition, several crosses produced female-biased sex ratios. Crosses involving C. elegans females and C. variegatus males produced only females, and in backcrosses involving hybrid females and C. elegans males, males made up approximately 25% of the offspring. All other crosses produced approximately 50% males. These sex ratios could be explained by genetic incompatibilities that occur, at least in part, on sex chromosomes. Thus, these results provide strong albeit indirect evidence that pupfish have XY chromosomal sex determination. The results of this study provide insight on the evolution of reproductive isolating mechanisms, particularly the role of Haldane's rule and the 'faster-male' theory in taxa lacking well-differentiated sex chromosomes.

  13. Aplastic Anemia in Two Patients with Sex Chromosome Aneuploidies.

    Science.gov (United States)

    Rush, Eric T; Schaefer, G Bradley; Sanger, Warren G; Coccia, Peter F

    2015-01-01

    Sex chromosome aneuploidies range in incidence from rather common to exceedingly rare and have a variable phenotype. We report 2 patients with sex chromosome aneuploidies who developed severe aplastic anemia requiring treatment. The first patient had tetrasomy X (48,XXXX) and presented at 9 years of age, and the second patient had trisomy X (47,XXX) and presented at 5 years of age. Although aplastic anemia has been associated with other chromosomal abnormalities, sex chromosome abnormalities have not been traditionally considered a risk factor for this condition. A review of the literature reveals that at least one other patient with a sex chromosome aneuploidy (45,X) has suffered from aplastic anemia and that other autosomal chromosomal anomalies have been described. Despite the uncommon nature of each condition, it is possible that the apparent association is coincidental. A better understanding of the genetic causes of aplastic anemia remains important. © 2015 S. Karger AG, Basel.

  14. Patterns of molecular evolution of an avian neo-sex chromosome.

    Science.gov (United States)

    Pala, Irene; Hasselquist, Dennis; Bensch, Staffan; Hansson, Bengt

    2012-12-01

    Newer parts of sex chromosomes, neo-sex chromosomes, offer unique possibilities for studying gene degeneration and sequence evolution in response to loss of recombination and population size decrease. We have recently described a neo-sex chromosome system in Sylvioidea passerines that has resulted from a fusion between the first half (10 Mb) of chromosome 4a and the ancestral sex chromosomes. In this study, we report the results of molecular analyses of neo-Z and neo-W gametologs and intronic parts of neo-Z and autosomal genes on the second half of chromosome 4a in three species within different Sylvioidea lineages (Acrocephalidea, Timaliidae, and Alaudidae). In line with hypotheses of neo-sex chromosome evolution, we observe 1) lower genetic diversity of neo-Z genes compared with autosomal genes, 2) moderate synonymous and weak nonsynonymous sequence divergence between neo-Z and neo-W gametologs, and 3) lower GC content on neo-W than neo-Z gametologs. Phylogenetic reconstruction of eight neo-Z and neo-W gametologs suggests that recombination continued after the split of Alaudidae from the rest of the Sylvioidea lineages (i.e., after ~42.2 Ma) and with some exceptions also after the split of Acrocephalidea and Timaliidae (i.e., after ~39.4 Ma). The Sylvioidea neo-sex chromosome shares classical evolutionary features with the ancestral sex chromosomes but, as expected from its more recent origin, shows weaker divergence between gametologs.

  15. Female meiotic sex chromosome inactivation in chicken.

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    Sam Schoenmakers

    2009-05-01

    Full Text Available During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW, whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.

  16. Genes and chromosome arrangements affecting sex ratio in the Mediterranean fruit fly, Ceratitis capitata (Wied.)

    International Nuclear Information System (INIS)

    Wood, R.J.; Kafu, A.A.; Rendon Arana, P.A.; Owusu-Daaku, K.; Alcock, R.M.; Hallows, J.A.; Busch-Petersen, E.; Mani, G.S.

    1997-01-01

    The MP (male producing) factor, which shows temperature sensitive meiotic drive favoring the Y chromosome, proved to be highly variable in spermatozoal deficiency in different cysts within a single testis. However, the overall loss of sperm corresponded almost precisely with the loss of females. The minimum proportion of females consistently obtained in inbred lines was about 30-35%. On the basis of parallel studies with the mosquito Aedes aegypti, variability between cysts is open to interpretation in terms of different rates of senescence. The T:Y(wp + )30C genetic sexing strain, which is designed to generate males with brown (wild type) puparia and females with white puparia, was contaminated artificially in a series of population experiments to investigate the pattern of breakdown. Wild type contamination with either sex caused an increase of brown pupae. The sex ratio became progressively distorted in favour of females after contamination with females, mated or unmated, but not after male contamination. The experiments revealed evidence of a low frequency of natural recombination between wp + and the translocation breakpoint on the Y chromosome, shown by the appearance of wp males. The frequency of male recombination (r) and the selection coefficient (s) against wp/wp were measured over 11 generations. The best fit to the observed data was obtained with r = (0.14 ± 0.04)% and s=(26.0 ± 2.7)%. Using these estimates to predict the frequency of wp + females and wp males for up to 100 generations, it was concluded that white males would never exceed 0.5% whereas the frequency of brown females was expected to exceed 33% after 25 generations. Published data on the mass reared strain, maintained with a population size of 240,000 adult flies, were subjected to the same analysis. A higher value of s between (38.0 ± 3.2)% and (52.0 ± 0.3)% was obtained under these conditions. Electrophoretic studies on esterases revealed a significantly higher activity in a recently

  17. Divergent Evolutionary Trajectories of Two Young, Homomorphic, and Closely Related Sex Chromosome Systems

    Science.gov (United States)

    Furman, Benjamin L S; Evans, Ben J

    2018-01-01

    Abstract There exists extraordinary variation among species in the degree and nature of sex chromosome divergence. However, much of our knowledge about sex chromosomes is based on comparisons between deeply diverged species with different ancestral sex chromosomes, making it difficult to establish how fast and why sex chromosomes acquire variable levels of divergence. To address this problem, we studied sex chromosome evolution in two species of African clawed frog (Xenopus), both of whom acquired novel systems for sex determination from a recent common ancestor, and both of whom have female (ZW/ZZ) heterogamy. Derived sex chromosomes of one species, X. laevis, have a small region of suppressed recombination that surrounds the sex determining locus, and have remained this way for millions of years. In the other species, X. borealis, a younger sex chromosome system exists on a different pair of chromosomes, but the region of suppressed recombination surrounding an unidentified sex determining gene is vast, spanning almost half of the sex chromosomes. Differences between these sex chromosome systems are also apparent in the extent of nucleotide divergence between the sex chromosomes carried by females. Our analyses also indicate that in autosomes of both of these species, recombination during oogenesis occurs more frequently and in different genomic locations than during spermatogenesis. These results demonstrate that new sex chromosomes can assume radically different evolutionary trajectories, with far-reaching genomic consequences. They also suggest that in some instances the origin of new triggers for sex determination may be coupled with rapid evolution sex chromosomes, including recombination suppression of large genomic regions. PMID:29608717

  18. Autosomal origin of sex chromosome in a polyploid plant

    Science.gov (United States)

    While theory on sex chromosome evolution is well developed, evidence of the early stages of this process remains elusive, in part because this process unfolded in many animals so long ago. The relatively recent and repeated evolution of separate sexes (dioecy) and sex chromosomes in plants, however,...

  19. Sex ratios

    OpenAIRE

    West, Stuart A; Reece, S E; Sheldon, Ben C

    2002-01-01

    Sex ratio theory attempts to explain variation at all levels (species, population, individual, brood) in the proportion of offspring that are male (the sex ratio). In many cases this work has been extremely successful, providing qualitative and even quantitative explanations of sex ratio variation. However, this is not always the situation, and one of the greatest remaining problems is explaining broad taxonomic patterns. Specifically, why do different organisms show so ...

  20. Environmental Exposure of Sperm Sex-Chromosomes: A Gender Selection Technique.

    Science.gov (United States)

    Oyeyipo, Ibukun P; van der Linde, Michelle; du Plessis, Stefan S

    2017-10-01

    Preconceptual sex selection is still a highly debatable process whereby X- and Y-chromosome-bearing spermatozoa are isolated prior to fertilization of the oocyte. Although various separation techniques are available, none can guarantee 100% accuracy. The aim of this study was to separate X- and Y-chromosome-bearing spermatozoa using methods based on the viability difference between the X- and Y-chromosome-bearing spermatozoa. A total of 18 experimental semen samples were used, written consent was obtained from all donors and results were analysed in a blinded fashion. Spermatozoa were exposed to different pH values (5.5, 6.5, 7.5, 8.5, and 9.5), increased temperatures (37°C, 41°C, and 45°C) and ROS level (50 μM, 750 μM, and 1,000 μM). The live and dead cell separation was done through a modified swim-up technique. Changes in the sex-chromosome ratio of samples were established by double-label fluorescent in situ hybridization (FISH) before and after processing. The results indicated successful enrichment of Xchromosome-bearing spermatozoa upon incubation in acidic media, increased temperatures, and elevated H 2 O 2 . This study demonstrated the potential role for exploring the physiological differences between X-and Y-chromosome-bearing spermatozoa in the development of preconceptual gender selection.

  1. Construction of physical maps for the sex-specific regions of papaya sex chromosomes

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    Na Jong-Kuk

    2012-05-01

    Full Text Available Abstract Background Papaya is a major fruit crop in tropical and subtropical regions worldwide. It is trioecious with three sex forms: male, female, and hermaphrodite. Sex determination is controlled by a pair of nascent sex chromosomes with two slightly different Y chromosomes, Y for male and Yh for hermaphrodite. The sex chromosome genotypes are XY (male, XYh (hermaphrodite, and XX (female. The papaya hermaphrodite-specific Yh chromosome region (HSY is pericentromeric and heterochromatic. Physical mapping of HSY and its X counterpart is essential for sequencing these regions and uncovering the early events of sex chromosome evolution and to identify the sex determination genes for crop improvement. Results A reiterate chromosome walking strategy was applied to construct the two physical maps with three bacterial artificial chromosome (BAC libraries. The HSY physical map consists of 68 overlapped BACs on the minimum tiling path, and covers all four HSY-specific Knobs. One gap remained in the region of Knob 1, the only knob structure shared between HSY and X, due to the lack of HSY-specific sequences. This gap was filled on the physical map of the HSY corresponding region in the X chromosome. The X physical map consists of 44 BACs on the minimum tiling path with one gap remaining in the middle, due to the nature of highly repetitive sequences. This gap was filled on the HSY physical map. The borders of the non-recombining HSY were defined genetically by fine mapping using 1460 F2 individuals. The genetically defined HSY spanned approximately 8.5 Mb, whereas its X counterpart extended about 5.4 Mb including a 900 Kb region containing the Knob 1 shared by the HSY and X. The 8.5 Mb HSY corresponds to 4.5 Mb of its X counterpart, showing 4 Mb (89% DNA sequence expansion. Conclusion The 89% increase of DNA sequence in HSY indicates rapid expansion of the Yh chromosome after genetic recombination was suppressed 2–3 million years ago. The

  2. Recurrent selection on the Winters sex-ratio genes in Drosophila simulans.

    Science.gov (United States)

    Kingan, Sarah B; Garrigan, Daniel; Hartl, Daniel L

    2010-01-01

    Selfish genes, such as meiotic drive elements, propagate themselves through a population without increasing the fitness of host organisms. X-linked (or Y-linked) meiotic drive elements reduce the transmission of the Y (X) chromosome and skew progeny and population sex ratios, leading to intense conflict among genomic compartments. Drosophila simulans is unusual in having a least three distinct systems of X chromosome meiotic drive. Here, we characterize naturally occurring genetic variation at the Winters sex-ratio driver (Distorter on the X or Dox), its progenitor gene (Mother of Dox or MDox), and its suppressor gene (Not Much Yang or Nmy), which have been previously mapped and characterized. We survey three North American populations as well as 13 globally distributed strains and present molecular polymorphism data at the three loci. We find that all three genes show signatures of selection in North America, judging from levels of polymorphism and skews in the site-frequency spectrum. These signatures likely result from the biased transmission of the driver and selection on the suppressor for the maintenance of equal sex ratios. Coalescent modeling indicates that the timing of selection is more recent than the age of the alleles, suggesting that the driver and suppressor are coevolving under an evolutionary "arms race." None of the Winters sex-ratio genes are fixed in D. simulans, and at all loci we find ancestral alleles, which lack the gene insertions and exhibit high levels of nucleotide polymorphism compared to the derived alleles. In addition, we find several "null" alleles that have mutations on the derived Dox background, which result in loss of drive function. We discuss the possible causes of the maintenance of presence-absence polymorphism in the Winters sex-ratio genes.

  3. Neo-sex Chromosomes in the Monarch Butterfly, Danaus plexippus

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    Andrew J. Mongue

    2017-10-01

    Full Text Available We report the discovery of a neo-sex chromosome in the monarch butterfly, Danaus plexippus, and several of its close relatives. Z-linked scaffolds in the D. plexippus genome assembly were identified via sex-specific differences in Illumina sequencing coverage. Additionally, a majority of the D. plexippus genome assembly was assigned to chromosomes based on counts of one-to-one orthologs relative to the butterfly Melitaea cinxia (with replication using two other lepidopteran species, in which genome scaffolds have been mapped to linkage groups. Sequencing coverage-based assessments of Z linkage combined with homology-based chromosomal assignments provided strong evidence for a Z-autosome fusion in the Danaus lineage, involving the autosome homologous to chromosome 21 in M. cinxia. Coverage analysis also identified three notable assembly errors resulting in chimeric Z-autosome scaffolds. Cytogenetic analysis further revealed a large W chromosome that is partially euchromatic, consistent with being a neo-W chromosome. The discovery of a neo-Z and the provisional assignment of chromosome linkage for >90% of D. plexippus genes lays the foundation for novel insights concerning sex chromosome evolution in this female-heterogametic model species for functional and evolutionary genomics.

  4. An Allometric Analysis of Sex and Sex Chromosome Dosage Effects on Subcortical Anatomy in Humans

    Science.gov (United States)

    Clasen, Liv; Giedd, Jay N.; Blumenthal, Jonathan; Lerch, Jason P.; Chakravarty, M. Mallar; Raznahan, Armin

    2016-01-01

    Structural neuroimaging of humans with typical and atypical sex-chromosome complements has established the marked influence of both Yand X-/Y-chromosome dosage on total brain volume (TBV) and identified potential cortical substrates for the psychiatric phenotypes associated with sex-chromosome aneuploidy (SCA). Here, in a cohort of 354 humans with varying karyotypes (XX, XY, XXX, XXY, XYY, XXYY, XXXXY), we investigate sex and SCA effects on subcortical size and shape; focusing on the striatum, pallidum and thalamus. We find large effect-size differences in the volume and shape of all three structures as a function of sex and SCA. We correct for TBV effects with a novel allometric method harnessing normative scaling rules for subcortical size and shape in humans, which we derive here for the first time. We show that all three subcortical volumes scale sublinearly with TBV among healthy humans, mirroring known relationships between subcortical volume and TBV among species. Traditional TBV correction methods assume linear scaling and can therefore invert or exaggerate sex and SCA effects on subcortical anatomy. Allometric analysis restricts sex-differences to: (1) greater pallidal volume (PV) in males, and (2) relative caudate head expansion and ventral striatum contraction in females. Allometric analysis of SCA reveals that supernumerary X- and Y-chromosomes both cause disproportionate reductions in PV, and coordinated deformations of striatopallidal shape. Our study provides a novel understanding of sex and sex-chromosome dosage effects on subcortical organization, using an allometric approach that can be generalized to other basic and clinical structural neuroimaging settings. SIGNIFICANCE STATEMENT Sex and sex-chromosome dosage (SCD) are known to modulate human brain size and cortical anatomy, but very little is known regarding their impact on subcortical structures that work with the cortex to subserve a range of behaviors in health and disease. Moreover

  5. Genetics, chromatin diminution, and sex chromosome evolution in the parasitic nematode genus Strongyloides.

    Science.gov (United States)

    Nemetschke, Linda; Eberhardt, Alexander G; Hertzberg, Hubertus; Streit, Adrian

    2010-10-12

    When chromatin diminution occurs during a cell division a portion of the chromatin is eliminated, resulting in daughter cells with a smaller amount of genetic material. In the parasitic roundworms Ascaris and Parascaris, chromatin diminution creates a genetic difference between the soma and the germline. However, the function of chromatin diminution remains a mystery, because the vast majority of the eliminated DNA is noncoding. Within the parasitic roundworm genus Strongyloides, S. stercoralis (in man) and S. ratti (in rat) employ XX/XO sex determination, but the situation in S. papillosus (in sheep) is different but controversial. We demonstrate genetically that S. papillosus employs sex-specific chromatin diminution to eliminate an internal portion of one of the two homologs of one chromosome pair in males. Contrary to ascarids, the eliminated DNA in S. papillosus contains a large number of genes. We demonstrate that the region undergoing diminution is homologous to the X chromosome of the closely related S. ratti. The flanking regions, which are not diminished, are homologous to the S. ratti autosome number I. Furthermore, we found that the diminished chromosome is not incorporated into sperm, resulting in a male-specific transmission ratio distortion. Our data indicate that on the evolutionary path to S. papillosus, the X chromosome fused with an autosome. Chromatin diminution serves to functionally restore an XX/XO sex-determining system. A consequence of the fusion and the process that copes with it is a transmission ratio distortion in males for certain loci. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. Klinefelter syndrome and other sex chromosomal aneuploidies

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    Graham John M

    2006-10-01

    Full Text Available Abstract The term Klinefelter syndrome (KS describes a group of chromosomal disorder in which there is at least one extra X chromosome to a normal male karyotype, 46,XY. XXY aneuploidy is the most common disorder of sex chromosomes in humans, with prevalence of one in 500 males. Other sex chromosomal aneuploidies have also been described, although they are much less frequent, with 48,XXYY and 48,XXXY being present in 1 per 17,000 to 1 per 50,000 male births. The incidence of 49,XXXXY is 1 per 85,000 to 100,000 male births. In addition, 46,XX males also exist and it is caused by translocation of Y material including sex determining region (SRY to the X chromosome during paternal meiosis. Formal cytogenetic analysis is necessary to make a definite diagnosis, and more obvious differences in physical features tend to be associated with increasing numbers of sex chromosomes. If the diagnosis is not made prenatally, 47,XXY males may present with a variety of subtle clinical signs that are age-related. In infancy, males with 47,XXY may have chromosomal evaluations done for hypospadias, small phallus or cryptorchidism, developmental delay. The school-aged child may present with language delay, learning disabilities, or behavioral problems. The older child or adolescent may be discovered during an endocrine evaluation for delayed or incomplete pubertal development with eunuchoid body habitus, gynecomastia, and small testes. Adults are often evaluated for infertility or breast malignancy. Androgen replacement therapy should begin at puberty, around age 12 years, in increasing dosage sufficient to maintain age appropriate serum concentrations of testosterone, estradiol, follicle stimulating hormone (FSH, and luteinizing hormone (LH. The effects on physical and cognitive development increase with the number of extra Xs, and each extra X is associated with an intelligence quotient (IQ decrease of approximately 15–16 points, with language most affected

  7. Conservation of sex chromosomes in lacertid lizards

    Czech Academy of Sciences Publication Activity Database

    Rovatsos, M.; Vukič, J.; Altmanová, M.; Johnson Pokorná, Martina; Moravec, J.; Kratochvíl, L.

    2016-01-01

    Roč. 25, č. 13 (2016), s. 3120-3126 ISSN 0962-1083 Institutional support: RVO:67985904 Keywords : lizards * molecular sex ing * reptiles * sex chromosomes Subject RIV: EG - Zoology Impact factor: 6.086, year: 2016

  8. Sex chromosomes and speciation in birds and other ZW systems.

    Science.gov (United States)

    Irwin, Darren E

    2018-02-14

    Theory and empirical patterns suggest a disproportionate role for sex chromosomes in evolution and speciation. Focusing on ZW sex determination (females ZW, males ZZ; the system in birds, many snakes, and lepidopterans), I review how evolutionary dynamics are expected to differ between the Z, W and the autosomes, discuss how these differences may lead to a greater role of the sex chromosomes in speciation and use data from birds to compare relative evolutionary rates of sex chromosomes and autosomes. Neutral mutations, partially or completely recessive beneficial mutations, and deleterious mutations under many conditions are expected to accumulate faster on the Z than on autosomes. Sexually antagonistic polymorphisms are expected to arise on the Z, raising the possibility of the spread of preference alleles. The faster accumulation of many types of mutations and the potential for complex evolutionary dynamics of sexually antagonistic traits and preferences contribute to a role for the Z chromosome in speciation. A quantitative comparison among a wide variety of bird species shows that the Z tends to have less within-population diversity and greater between-species differentiation than the autosomes, likely due to both adaptive evolution and a greater rate of fixation of deleterious alleles. The W chromosome also shows strong potential to be involved in speciation, in part because of its co-inheritance with the mitochondrial genome. While theory and empirical evidence suggest a disproportionate role for sex chromosomes in speciation, the importance of sex chromosomes is moderated by their small size compared to the whole genome. © 2018 John Wiley & Sons Ltd.

  9. Untangling the Contributions of Sex-Specific Gene Regulation and X-Chromosome Dosage to Sex-Biased Gene Expression in Caenorhabditis elegans

    Science.gov (United States)

    Kramer, Maxwell; Rao, Prashant; Ercan, Sevinc

    2016-01-01

    Dosage compensation mechanisms equalize the level of X chromosome expression between sexes. Yet the X chromosome is often enriched for genes exhibiting sex-biased, i.e., imbalanced expression. The relationship between X chromosome dosage compensation and sex-biased gene expression remains largely unexplored. Most studies determine sex-biased gene expression without distinguishing between contributions from X chromosome copy number (dose) and the animal’s sex. Here, we uncoupled X chromosome dose from sex-specific gene regulation in Caenorhabditis elegans to determine the effect of each on X expression. In early embryogenesis, when dosage compensation is not yet fully active, X chromosome dose drives the hermaphrodite-biased expression of many X-linked genes, including several genes that were shown to be responsible for hermaphrodite fate. A similar effect is seen in the C. elegans germline, where X chromosome dose contributes to higher hermaphrodite X expression, suggesting that lack of dosage compensation in the germline may have a role in supporting higher expression of X chromosomal genes with female-biased functions in the gonad. In the soma, dosage compensation effectively balances X expression between the sexes. As a result, somatic sex-biased expression is almost entirely due to sex-specific gene regulation. These results suggest that lack of dosage compensation in different tissues and developmental stages allow X chromosome copy number to contribute to sex-biased gene expression and function. PMID:27356611

  10. Molecular diagnostic testing for Klinefelter syndrome and other male sex chromosome aneuploidies

    Directory of Open Access Journals (Sweden)

    Hager Karl

    2012-04-01

    Full Text Available Abstract Background Male sex chromosome aneuploidies are underdiagnosed despite concomitant physical and behavioral manifestations. Objective To develop a non-invasive, rapid and high-throughput molecular diagnostic assay for detection of male sex chromosome aneuploidies, including 47,XXY (Klinefelter, 47,XYY, 48,XXYY and 48,XXXY syndromes. Methods The assay utilizes three XYM and four XA markers to interrogate Y:X and X:autosome ratios, respectively. The seven markers were PCR amplified using genomic DNA isolated from a cohort of 323 males with aneuploid (n = 117 and 46,XY (n = 206 karyotypes. The resulting PCR products were subjected to Pyrosequencing, a quantitative DNA sequencing method. Results Receiver operator characteristic (ROC curves were used to establish thresholds for the discrimination of aneuploid from normal samples. The XYM markers permitted the identification of 47,XXY, 48,XXXY and 47,XYY syndromes with 100% sensitivity and specificity in both purified DNA and buccal swab samples. The 48,XXYY karyotype was delineated by XA marker data from 46,XY; an X allele threshold of 43% also permitted detection of 48,XXYY with 100% sensitivity and specificity. Analysis of X chromosome-specific biallelic SNPs demonstrated that 43 of 45 individuals (96% with 48,XXYY karyotype had two distinct X chromosomes, while 2 (4% had a duplicate X, providing evidence that 48,XXYY may result from nondisjunction during early mitotic divisions of a 46,XY embryo. Conclusions Quantitative Pyrosequencing, with high-throughput potential, can detect male sex chromosome aneuploidies with 100% sensitivity.

  11. Distribution of sex chromosomes (XY) in lymphocyte metaphase spreads of dairy bulls

    OpenAIRE

    Kotikalapudi Rosaiah; Patel Rajesh Kumar; Medidi Hemanth; Sugali Nagaraju Naik

    2013-01-01

    Position of autosome and sex chromosomes in metaphase spreads is grate concerned of Cytogeneticians worldwide to understand cell biology. A few isolated studies have been conducted for the distribution of chromosomes in metaphase spread. Our studies reveal that most sex chromosomes (XY) remain on periphery and semi-periphery, 84.16% for X and 86.97% for Y respectively, in round metaphase spreads. The application of sex chromosome position in metaphase sprea...

  12. Sex Chromosome Evolution, Heterochiasmy, and Physiological QTL in the Salmonid Brook Charr Salvelinus fontinalis

    Directory of Open Access Journals (Sweden)

    Ben J.G. Sutherland

    2017-08-01

    Full Text Available Whole-genome duplication (WGD can have large impacts on genome evolution, and much remains unknown about these impacts. This includes the mechanisms of coping with a duplicated sex determination system and whether this has an impact on increasing the diversity of sex determination mechanisms. Other impacts include sexual conflict, where alleles having different optimums in each sex can result in sequestration of genes into nonrecombining sex chromosomes. Sex chromosome development itself may involve sex-specific recombination rate (i.e., heterochiasmy, which is also poorly understood. The family Salmonidae is a model system for these phenomena, having undergone autotetraploidization and subsequent rediploidization in most of the genome at the base of the lineage. The salmonid master sex determining gene is known, and many species have nonhomologous sex chromosomes, putatively due to transposition of this gene. In this study, we identify the sex chromosome of Brook Charr Salvelinus fontinalis and compare sex chromosome identities across the lineage (eight species and four genera. Although nonhomology is frequent, homologous sex chromosomes and other consistencies are present in distantly related species, indicating probable convergence on specific sex and neo-sex chromosomes. We also characterize strong heterochiasmy with 2.7-fold more crossovers in maternal than paternal haplotypes with paternal crossovers biased to chromosome ends. When considering only rediploidized chromosomes, the overall heterochiasmy trend remains, although with only 1.9-fold more recombination in the female than the male. Y chromosome crossovers are restricted to a single end of the chromosome, and this chromosome contains a large interspecific inversion, although its status between males and females remains unknown. Finally, we identify quantitative trait loci (QTL for 21 unique growth, reproductive, and stress-related phenotypes to improve knowledge of the genetic

  13. Dynamics of vertebrate sex chromosome evolution: from equal size to giants and dwarfs.

    Science.gov (United States)

    Schartl, Manfred; Schmid, Michael; Nanda, Indrajit

    2016-06-01

    The Y and W chromosomes of mammals and birds are known to be small because most of their genetic content degenerated and were lost due to absence of recombination with the X or Z, respectively. Thus, a picture has emerged of ever-shrinking Ys and Ws that may finally even fade into disappearance. We review here the large amount of literature on sex chromosomes in vertebrate species and find by taking a closer look, particularly at the sex chromosomes of fishes, amphibians and reptiles where several groups have evolutionary younger chromosomes than those of mammals and birds, that the perception of sex chromosomes being doomed to size reduction is incomplete. Here, sex-determining mechanisms show a high turnover and new sex chromosomes appear repeatedly. In many species, Ys and Ws are larger than their X and Z counterparts. This brings up intriguing perspectives regarding the evolutionary dynamics of sex chromosomes. It can be concluded that, due to accumulation of repetitive DNA and transposons, the Y and W chromosomes can increase in size during the initial phase of their differentiation.

  14. Comparative Sex Chromosome Genomics in Snakes: Differentiation, Evolutionary Strata, and Lack of Global Dosage Compensation

    Science.gov (United States)

    Zektser, Yulia; Mahajan, Shivani; Bachtrog, Doris

    2013-01-01

    Snakes exhibit genetic sex determination, with female heterogametic sex chromosomes (ZZ males, ZW females). Extensive cytogenetic work has suggested that the level of sex chromosome heteromorphism varies among species, with Boidae having entirely homomorphic sex chromosomes, Viperidae having completely heteromorphic sex chromosomes, and Colubridae showing partial differentiation. Here, we take a genomic approach to compare sex chromosome differentiation in these three snake families. We identify homomorphic sex chromosomes in boas (Boidae), but completely heteromorphic sex chromosomes in both garter snakes (Colubridae) and pygmy rattlesnake (Viperidae). Detection of W-linked gametologs enables us to establish the presence of evolutionary strata on garter and pygmy rattlesnake sex chromosomes where recombination was abolished at different time points. Sequence analysis shows that all strata are shared between pygmy rattlesnake and garter snake, i.e., recombination was abolished between the sex chromosomes before the two lineages diverged. The sex-biased transmission of the Z and its hemizygosity in females can impact patterns of molecular evolution, and we show that rates of evolution for Z-linked genes are increased relative to their pseudoautosomal homologs, both at synonymous and amino acid sites (even after controlling for mutational biases). This demonstrates that mutation rates are male-biased in snakes (male-driven evolution), but also supports faster-Z evolution due to differential selective effects on the Z. Finally, we perform a transcriptome analysis in boa and pygmy rattlesnake to establish baseline levels of sex-biased expression in homomorphic sex chromosomes, and show that heteromorphic ZW chromosomes in rattlesnakes lack chromosome-wide dosage compensation. Our study provides the first full scale overview of the evolution of snake sex chromosomes at the genomic level, thus greatly expanding our knowledge of reptilian and vertebrate sex chromosomes

  15. Small but mighty: the evolutionary dynamics of W and Y sex chromosomes.

    Science.gov (United States)

    Mank, Judith E

    2012-01-01

    Although sex chromosomes have been the focus of a great deal of scientific scrutiny, most interest has centred on understanding the evolution and relative importance of X and Z chromosomes. By contrast, the sex-limited W and Y chromosomes have received far less attention, both because of their generally degenerate nature and the difficulty in studying non-recombining and often highly heterochromatic genomic regions. However, recent theory and empirical evidence suggest that the W and Y chromosomes play a far more important role in sex-specific fitness traits than would be expected based on their size alone, and this importance may explain the persistence of some Y and W chromosomes in the face of powerful degradative forces. In addition to their role in fertility and fecundity, the sex-limited nature of these genomic regions results in unique evolutionary forces acting on Y and W chromosomes, implicating them as potentially major contributors to sexual selection and speciation. Recent empirical studies have borne out these predictions and revealed that some W and Y chromosomes play a vital role in key sex-specific evolutionary processes.

  16. Female heterogamety in Madagascar chameleons (Squamata: Chamaeleonidae: Furcifer): differentiation of sex and neo-sex chromosomes

    Science.gov (United States)

    Rovatsos, Michail; Pokorná, Martina Johnson; Altmanová, Marie; Kratochvíl, Lukáš

    2015-01-01

    Amniotes possess variability in sex determining mechanisms, however, this diversity is still only partially known throughout the clade and sex determining systems still remain unknown even in such a popular and distinctive lineage as chameleons (Squamata: Acrodonta: Chamaeleonidae). Here, we present evidence for female heterogamety in this group. The Malagasy giant chameleon (Furcifer oustaleti) (chromosome number 2n = 22) possesses heteromorphic Z and W sex chromosomes with heterochromatic W. The panther chameleon (Furcifer pardalis) (2n = 22 in males, 21 in females), the second most popular chameleon species in the world pet trade, exhibits a rather rare Z1Z1Z2Z2/Z1Z2W system of multiple sex chromosomes, which most likely evolved from W-autosome fusion. Notably, its neo-W chromosome is partially heterochromatic and its female-specific genetic content has expanded into the previously autosomal region. Showing clear evidence for genotypic sex determination in the panther chameleon, we resolve the long-standing question of whether or not environmental sex determination exists in this species. Together with recent findings in other reptile lineages, our work demonstrates that female heterogamety is widespread among amniotes, adding another important piece to the mosaic of knowledge on sex determination in amniotes needed to understand the evolution of this important trait. PMID:26286647

  17. Small but mighty: the evolutionary dynamics of W and Y sex chromosomes

    Science.gov (United States)

    2012-01-01

    Although sex chromosomes have been the focus of a great deal of scientific scrutiny, most interest has centred on understanding the evolution and relative importance of X and Z chromosomes. By contrast, the sex-limited W and Y chromosomes have received far less attention, both because of their generally degenerate nature and the difficulty in studying non-recombining and often highly heterochromatic genomic regions. However, recent theory and empirical evidence suggest that the W and Y chromosomes play a far more important role in sex-specific fitness traits than would be expected based on their size alone, and this importance may explain the persistence of some Y and W chromosomes in the face of powerful degradative forces. In addition to their role in fertility and fecundity, the sex-limited nature of these genomic regions results in unique evolutionary forces acting on Y and W chromosomes, implicating them as potentially major contributors to sexual selection and speciation. Recent empirical studies have borne out these predictions and revealed that some W and Y chromosomes play a vital role in key sex-specific evolutionary processes. PMID:22038285

  18. ON THE TOPOGRAPHY OF THE SEX- CHROMOSOME IN

    Indian Academy of Sciences (India)

    over, we endeavoured to find the relative distribution of these genes in their chromosome, and to determine the distance between them, having in view the construction of a map of the sex-chromosome of fowls. We studied the following genes (in ...

  19. A Role for the X Chromosome in Sex Differences in Variability in General Intelligence?

    Science.gov (United States)

    Johnson, Wendy; Carothers, Andrew; Deary, Ian J

    2009-11-01

    There is substantial evidence that males are more variable than females in general intelligence. In recent years, researchers have presented this as a reason that, although there is little, if any, mean sex difference in general intelligence, males tend to be overrepresented at both ends of its overall distribution. Part of the explanation could be the presence of genes on the X chromosome related both to syndromal disorders involving mental retardation and to population variation in general intelligence occurring normally. Genes on the X chromosome appear overrepresented among genes with known involvement in mental retardation, which is consistent with a model we developed of the population distribution of general intelligence as a mixture of two normal distributions. Using this model, we explored the expected ratios of males to females at various points in the distribution and estimated the proportion of variance in general intelligence potentially due to genes on the X chromosome. These estimates provide clues to the extent to which biologically based sex differences could be manifested in the environment as sex differences in displayed intellectual abilities. We discuss these observations in the context of sex differences in specific cognitive abilities and evolutionary theories of sexual selection. © 2009 Association for Psychological Science.

  20. Turnover of sex chromosomes induced by sexual conflict

    NARCIS (Netherlands)

    van Doorn, G. S.; Kirkpatrick, Mark

    2007-01-01

    Sex-determination genes are among the most fluid features of the genome in many groups of animals(1,2). In some taxa the master sex-determining gene moves frequently between chromosomes, whereas in other taxa different genes have been recruited to determine the sex of the zygotes. There is a well

  1. Genetic architecture of sex determination in fish: Applications to sex ratio control in aquaculture

    Directory of Open Access Journals (Sweden)

    Paulino eMartínez

    2014-09-01

    Full Text Available Controlling the sex ratio is essential in finfish farming. A balanced sex ratio is usually good for broodstock management, since it enables to develop appropriate breeding schemes. However, in some species the production of monosex populations is desirable because the existence of sexual dimorphism, primarily in growth or first time of sexual maturation, but also in color or shape, can render one sex more valuable. The knowledge of the genetic architecture of sex determination (SD is convenient for controlling sex ratio and for the implementation of breeding programs. Unlike mammals and birds, which show highly conserved master genes that control a conserved genetic network responsible for gonad differentiation (GD, a huge diversity of SD mechanisms has been reported in fish. Despite theory predictions, more than one gene is in many cases involved in fish SD and genetic differences have been observed in the GD network. Environmental factors also play a relevant role and epigenetic mechanisms are becoming increasingly recognized for the establishment and maintenance of the GD pathways. Although major genetic factors are frequently involved in fish SD, these observations strongly suggest that SD in this group resembles a complex trait. Accordingly, the application of quantitative genetics combined with genomic tools is desirable to address its study and in fact, when applied, it has frequently demonstrated a multigene trait interacting with environmental factors in model and cultured fish species. This scenario has notable implications for aquaculture and, depending upon the species, from chromosome manipulation or environmental control techniques up to classical selection or marker assisted selection programs, are being applied. In this review, we selected four relevant species or fish groups to illustrate this diversity and hence the technologies that can be used by the industry for the control of sex ratio: turbot and European sea bass, two

  2. Increased high-density lipoprotein cholesterol levels in mice with XX versus XY sex chromosomes.

    Science.gov (United States)

    Link, Jenny C; Chen, Xuqi; Prien, Christopher; Borja, Mark S; Hammerson, Bradley; Oda, Michael N; Arnold, Arthur P; Reue, Karen

    2015-08-01

    The molecular mechanisms underlying sex differences in dyslipidemia are poorly understood. We aimed to distinguish genetic and hormonal regulators of sex differences in plasma lipid levels. We assessed the role of gonadal hormones and sex chromosome complement on lipid levels using the four core genotypes mouse model (XX females, XX males, XY females, and XY males). In gonadally intact mice fed a chow diet, lipid levels were influenced by both male-female gonadal sex and XX-XY chromosome complement. Gonadectomy of adult mice revealed that the male-female differences are dependent on acute effects of gonadal hormones. In both intact and gonadectomized animals, XX mice had higher HDL cholesterol (HDL-C) levels than XY mice, regardless of male-female sex. Feeding a cholesterol-enriched diet produced distinct patterns of sex differences in lipid levels compared with a chow diet, revealing the interaction of gonadal and chromosomal sex with diet. Notably, under all dietary and gonadal conditions, HDL-C levels were higher in mice with 2 X chromosomes compared with mice with an X and Y chromosome. By generating mice with XX, XY, and XXY chromosome complements, we determined that the presence of 2 X chromosomes, and not the absence of the Y chromosome, influences HDL-C concentration. We demonstrate that having 2 X chromosomes versus an X and Y chromosome complement drives sex differences in HDL-C. It is conceivable that increased expression of genes escaping X-inactivation in XX mice regulates downstream processes to establish sexual dimorphism in plasma lipid levels. © 2015 American Heart Association, Inc.

  3. Repetitive sequences and epigenetic modification: inseparable partners play important roles in the evolution of plant sex chromosomes.

    Science.gov (United States)

    Li, Shu-Fen; Zhang, Guo-Jun; Yuan, Jin-Hong; Deng, Chuan-Liang; Gao, Wu-Jun

    2016-05-01

    The present review discusses the roles of repetitive sequences played in plant sex chromosome evolution, and highlights epigenetic modification as potential mechanism of repetitive sequences involved in sex chromosome evolution. Sex determination in plants is mostly based on sex chromosomes. Classic theory proposes that sex chromosomes evolve from a specific pair of autosomes with emergence of a sex-determining gene(s). Subsequently, the newly formed sex chromosomes stop recombination in a small region around the sex-determining locus, and over time, the non-recombining region expands to almost all parts of the sex chromosomes. Accumulation of repetitive sequences, mostly transposable elements and tandem repeats, is a conspicuous feature of the non-recombining region of the Y chromosome, even in primitive one. Repetitive sequences may play multiple roles in sex chromosome evolution, such as triggering heterochromatization and causing recombination suppression, leading to structural and morphological differentiation of sex chromosomes, and promoting Y chromosome degeneration and X chromosome dosage compensation. In this article, we review the current status of this field, and based on preliminary evidence, we posit that repetitive sequences are involved in sex chromosome evolution probably via epigenetic modification, such as DNA and histone methylation, with small interfering RNAs as the mediator.

  4. Neurogenin 3 Mediates Sex Chromosome Effects on the Generation of Sex Differences in Hypothalamic Neuronal Development

    Directory of Open Access Journals (Sweden)

    Maria Julia Scerbo

    2014-07-01

    Full Text Available The organizational action of testosterone during critical periods of development is the cause of numerous sex differences in the brain. However, sex differences in neuritogenesis have been detected in primary neuronal hypothalamic cultures prepared before the peak of testosterone production by fetal testis. In the present study we assessed the hypothesis of that cell-autonomous action of sex chromosomes can differentially regulate the expression of the neuritogenic gene neurogenin 3 (Ngn3 in male and female hypothalamic neurons, generating sex differences in neuronal development. Neuronal cultures were prepared from male and female E14 mouse hypothalami, before the fetal peak of testosterone. Female neurons showed enhanced neuritogenesis and higher expression of Ngn3 than male neurons. The silencing of Ngn3 abolished sex differences in neuritogenesis, decreasing the differentiation of female neurons. The sex difference in Ngn3 expression was determined by sex chromosomes, as demonstrated using the four core genotypes mouse model, in which a spontaneous deletion of the testis-determining gene Sry from the Y chromosome was combined with the insertion of the Sry gene onto an autosome. In addition, the expression of Ngn3, which is also known to mediate the neuritogenic actions of estradiol, was increased in the cultures treated with the hormone, but only in those from male embryos. Furthermore, the hormone reversed the sex differences in neuritogenesis promoting the differentiation of male neurons. These findings indicate that Ngn3 mediates both cell-autonomous actions of sex chromosomes and hormonal effects on neuritogenesis.

  5. Live birth sex ratios and father's geographic origins in Jerusalem, 1964-1976.

    Science.gov (United States)

    Groeger, J; Opler, M; Kleinhaus, K; Perrin, M C; Calderon-Margalit, R; Manor, O; Paltiel, O; Conley, D; Harlap, S; Malaspina, D

    2017-05-06

    To examine whether ancestry influenced sex ratios of offspring in a birth cohort before parental antenatal sex selection influenced offspring sex. We measured the sex ratio as the percent of males according to countries of birth of paternal and maternal grandfathers in 91,459 live births from 1964 to 1976 in the Jerusalem Perinatal Study. Confidence limits (CI) were computed based on an expected sex ratio of 1.05, which is 51.4% male. Of all live births recorded, 51.4% were male. Relative to Jewish ancestry (51.4% males), significantly more males (1,761) were born to Muslim ancestry (54.5, 95% CI = 52.1-56.8, P = 0.01). Among the former, sex ratios were not significantly associated with paternal or maternal age, education, or offspring's birth order. Consistent with a preference for male offspring, the sex ratio decreased despite increasing numbers of births over the 13-year period. Sex ratios were not affected by maternal or paternal origins in North Africa or Europe. However, the offspring whose paternal grandfathers were born in Western Asia included fewer males than expected (50.7, 50.1-51.3, P = 0.02), whether the father was born abroad (50.7) or in Israel (50.8). This was observed for descendents of paternal grandfathers born in Lebanon (47.6), Turkey (49.9), Yemen & Aden (50.2), Iraq (50.5), Afghanistan (50.5), Syria (50.6), and Cyprus (50.7); but not for those from India (51.5) or Iran (51.9). The West Asian group showed the strongest decline in sex ratios with increasing paternal family size. A decreased sex ratio associated with ancestry in Western Asia is consistent with reduced ability to bear sons by a subset of Jewish men in the Jerusalem cohort. Lower sex ratios may be because of pregnancy stress, which may be higher in this subgroup. Alternatively, a degrading Y chromosome haplogroup or other genetic or epigenetic differences on male germ lines could affect birth ratios, such as differential exposure to an environmental agent, dietary

  6. Sexually antagonistic "zygotic drive" of the sex chromosomes.

    Directory of Open Access Journals (Sweden)

    William R Rice

    2008-12-01

    Full Text Available Genomic conflict is perplexing because it causes the fitness of a species to decline rather than improve. Many diverse forms of genomic conflict have been identified, but this extant tally may be incomplete. Here, we show that the unusual characteristics of the sex chromosomes can, in principle, lead to a previously unappreciated form of sexual genomic conflict. The phenomenon occurs because there is selection in the heterogametic sex for sex-linked mutations that harm the sex of offspring that does not carry them, whenever there is competition among siblings. This harmful phenotype can be expressed as an antagonistic green-beard effect that is mediated by epigenetic parental effects, parental investment, and/or interactions among siblings. We call this form of genomic conflict sexually antagonistic "zygotic drive", because it is functionally equivalent to meiotic drive, except that it operates during the zygotic and postzygotic stages of the life cycle rather than the meiotic and gametic stages. A combination of mathematical modeling and a survey of empirical studies is used to show that sexually antagonistic zygotic drive is feasible, likely to be widespread in nature, and that it can promote a genetic "arms race" between the homo- and heteromorphic sex chromosomes. This new category of genomic conflict has the potential to strongly influence other fundamental evolutionary processes, such as speciation and the degeneration of the Y and W sex chromosomes. It also fosters a new genetic hypothesis for the evolution of enigmatic fitness-reducing traits like the high frequency of spontaneous abortion, sterility, and homosexuality observed in humans.

  7. The role of chromosomal rearrangements in the evolution of Silene latifolia sex chromosomes

    Czech Academy of Sciences Publication Activity Database

    Hobza, Roman; Kejnovský, Eduard; Vyskot, Boris; Widmer, A.

    2007-01-01

    Roč. 278, č. 6 (2007), s. 633-638 ISSN 1617-4615 R&D Projects: GA ČR(CZ) GA204/05/2097; GA ČR(CZ) GA521/06/0056 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : chromosomal rearrangements * sex chromosomes * FISH Subject RIV: BO - Biophysics Impact factor: 2.978, year: 2007

  8. Sex chromosome diversity in Armenian toad grasshoppers (Orthoptera, Acridoidea, Pamphagidae)

    Science.gov (United States)

    Bugrov, Alexander G.; Jetybayev, Ilyas E.; Karagyan, Gayane H.; Rubtsov, Nicolay B.

    2016-01-01

    Abstract Although previous cytogenetic analysis of Pamphagidae grasshoppers pointed to considerable karyotype uniformity among most of the species in the family, our study of species from Armenia has discovered other, previously unknown karyotypes, differing from the standard for Pamphagidae mainly in having unusual sets of sex chromosomes. Asiotmethis turritus (Fischer von Waldheim, 1833), Paranocaracris rubripes (Fischer von Waldheim, 1846), and Nocaracris cyanipes (Fischer von Waldheim, 1846) were found to have the karyotype 2n♂=16+neo-XY and 2n♀=16+neo-XX, the neo-X chromosome being the result of centromeric fusion of an ancient acrocentric X chromosome and a large acrocentric autosome. The karyotype of Paranothrotes opacus (Brunner von Wattenwyl, 1882) was found to be 2n♂=14+X1X2Y and 2n♀=14+X1X1X2X2., the result of an additional chromosome rearrangement involving translocation of the neo-Y and another large autosome. Furthermore, evolution of the sex chromosomes in these species has involved different variants of heterochromatinization and miniaturization of the neo-Y. The karyotype of Eremopeza festiva (Saussure, 1884), in turn, appeared to have the standard sex determination system described earlier for Pamphagidae grasshoppers, 2n♂=18+X0 and 2n♀=18+XX, but all the chromosomes of this species were found to have small second C-positive arms. Using fluorescent in situ hybridization (FISH) with 18S rDNA and telomeric (TTAGG)n DNA repeats to yield new data on the structural organization of chromosomes in the species studied, we found that for most of them, clusters of repeats homologous to 18S rDNA localize on two, three or four pairs of autosomes and on the X. In Eremopeza festiva, however, FISH with labelled 18S rDNA painted C-positive regions of all autosomes and the X chromosome; clusters of telomeric repeats localized primarily on the ends of the chromosome arms. Overall, we conclude that the different stages of neo-Y degradation revealed in

  9. The evolution of sex ratios and sex-determining systems

    NARCIS (Netherlands)

    Uller, Tobias; Pen, Ido; Wapstra, Erik; Beukeboom, Leo W.; Komdeur, Jan

    Sex determination is a fundamental process governed by diverse mechanisms. Sex ratio selection is commonly implicated in the evolution of sex-determining systems, although formal models are rare. Here, we argue that, although sex ratio selection can induce shifts in sex determination, genomic

  10. Rapid neo-sex chromosome evolution and incipient speciation in a major forest pest.

    Science.gov (United States)

    Bracewell, Ryan R; Bentz, Barbara J; Sullivan, Brian T; Good, Jeffrey M

    2017-11-17

    Genome evolution is predicted to be rapid following the establishment of new (neo) sex chromosomes, but it is not known if neo-sex chromosome evolution plays an important role in speciation. Here we combine extensive crossing experiments with population and functional genomic data to examine neo-XY chromosome evolution and incipient speciation in the mountain pine beetle. We find a broad continuum of intrinsic incompatibilities in hybrid males that increase in strength with geographic distance between reproductively isolated populations. This striking progression of reproductive isolation is coupled with extensive gene specialization, natural selection, and elevated genetic differentiation on both sex chromosomes. Closely related populations isolated by hybrid male sterility also show fixation of alternative neo-Y haplotypes that differ in structure and male-specific gene content. Our results suggest that neo-sex chromosome evolution can drive rapid functional divergence between closely related populations irrespective of ecological drivers of divergence.

  11. Sex chromosome aneuploidy in cytogenetic findings of referral patients from south of Iran

    Directory of Open Access Journals (Sweden)

    Najmeh Jouyan

    2012-01-01

    Full Text Available Background: Chromosome abnormality (CA including Sex chromosomes abnormality (SCAs is one of the most important causes of disordered sexual development and infertility. SCAs formed by numerical or structural alteration in X and Y chromosomes, are the most frequently CA encountered at both prenatal diagnosis and at birth. Objective: This study describes cytogenetic findings of cases suspected with CA referred for cytogenetic study. Materials and Methods: Blood samples of 4151 patients referred for cytogenetic analysis were cultured for chromosome preparation. Karyotypes were prepared for all samples and G-Banded chromosomes were analyzed using x100 objective lens. Sex chromosome aneuploidy cases were analyzed and categorized in two groups of Turners and Klinefelter’s syndrome (KFS. Results: Out of 230 (5.54% cases with chromosomally abnormal karyotype, 122 (30% cases suspected of sexual disorder showed SCA including 46% Turner’s syndrome, 46% KFS and the remaining other sex chromosome abnormalities. The frequency of classic and mosaic form of Turner’s syndrome was 33% and 67%, this was 55% and 45% for KFS, respectively. Conclusion: This study shows a relatively high sex chromosome abnormality in this region and provides cytogenetic data to assist clinicians and genetic counselors to determine the priority of requesting cytogenetic study. Differences between results from various reports can be due to different genetic background or ethnicity.

  12. Psychotic disorder and its characteristics in sex chromosome aneuploidies

    Directory of Open Access Journals (Sweden)

    Annapia Verri

    2009-09-01

    Full Text Available Sex chromosome anomalies have been associated with psychoses. We report a patient with XYY chromosome anomaly who developed a paranoid psychosis. The second case deal with a 51-year-old woman affected by Turner Syndrome and Psychotic Disorder, with a prevalent somatic and sexual focus.

  13. Identification of the sex-determining locus in grass puffer (Takifugu niphobles) provides evidence for sex-chromosome turnover in a subset of Takifugu species

    Science.gov (United States)

    Atsumi, Kazufumi; Kamiya, Takashi; Nozawa, Aoi; Aoki, Yuma; Tasumi, Satoshi; Koyama, Takashi; Nakamura, Osamu; Suzuki, Yuzuru

    2018-01-01

    There is increasing evidence for frequent turnover in sex chromosomes in vertebrates. Yet experimental systems suitable for tracing the detailed process of turnover are rare. In theory, homologous turnover is possible if the new sex-determining locus is established on the existing sex-chromosome. However, there is no empirical evidence for such an event. The genus Takifugu includes fugu (Takifugu rubripes) and its two closely-related species whose sex is most likely determined by a SNP at the Amhr2 locus. In these species, males are heterozygous, with G and C alleles at the SNP site, while females are homozygous for the C allele. To determine if a shift in the sex-determining locus occurred in another member of this genus, we used genetic mapping to characterize the sex-chromosome systems of Takifugu niphobles. We found that the G allele of Amhr2 is absent in T. niphobles. Nevertheless, our initial mapping suggests a linkage between the phenotypic sex and the chromosome 19, which harbors the Amhr2 locus. Subsequent high-resolution analysis using a sex-reversed fish demonstrated that the sex-determining locus maps to the proximal end of chromosome 19, far from the Amhr2 locus. Thus, it is likely that homologous turnover involving these species has occurred. The data also showed that there is a male-specific reduction of recombination around the sex-determining locus. Nevertheless, no evidence for sex-chromosome differentiation was detected: the reduced recombination depended on phenotypic sex rather than genotypic sex; no X- or Y-specific maker was obtained; the YY individual was viable. Furthermore, fine-scale mapping narrowed down the new sex-determining locus to the interval corresponding to approximately 300-kb of sequence in the fugu genome. Thus, T. niphobles is determined to have a young and small sex-determining region that is suitable for studying an early phase of sex-chromosome evolution and the mechanisms underlying turnover of sex chromosome. PMID

  14. Psychoeducational Implications of Sex Chromosome Anomalies

    Science.gov (United States)

    Wodrich, David L.; Tarbox, Jennifer

    2008-01-01

    Numerous anomalies involving the sex chromosomes (X or Y) have been documented and their impact on development, learning, and behavior studied. This article reviews three of these disorders, Turner syndrome, Klinefelter syndrome, and Lesch-Nyhan disease. Each of these three is associated with one or more selective impairments or behavioral…

  15. Multiple sex-associated regions and a putative sex chromosome in zebrafish revealed by RAD mapping and population genomics.

    Directory of Open Access Journals (Sweden)

    Jennifer L Anderson

    Full Text Available Within vertebrates, major sex determining genes can differ among taxa and even within species. In zebrafish (Danio rerio, neither heteromorphic sex chromosomes nor single sex determination genes of large effect, like Sry in mammals, have yet been identified. Furthermore, environmental factors can influence zebrafish sex determination. Although progress has been made in understanding zebrafish gonad differentiation (e.g. the influence of germ cells on gonad fate, the primary genetic basis of zebrafish sex determination remains poorly understood. To identify genetic loci associated with sex, we analyzed F(2 offspring of reciprocal crosses between Oregon *AB and Nadia (NA wild-type zebrafish stocks. Genome-wide linkage analysis, using more than 5,000 sequence-based polymorphic restriction site associated (RAD-tag markers and population genomic analysis of more than 30,000 single nucleotide polymorphisms in our *ABxNA crosses revealed a sex-associated locus on the end of the long arm of chr-4 for both cross families, and an additional locus in the middle of chr-3 in one cross family. Additional sequencing showed that two SNPs in dmrt1 previously suggested to be functional candidates for sex determination in a cross of ABxIndia wild-type zebrafish, are not associated with sex in our AB fish. Our data show that sex determination in zebrafish is polygenic and that different genes may influence sex determination in different strains or that different genes become more important under different environmental conditions. The association of the end of chr-4 with sex is remarkable because, unique in the karyotype, this chromosome arm shares features with known sex chromosomes: it is highly heterochromatic, repetitive, late replicating, and has reduced recombination. Our results reveal that chr-4 has functional and structural properties expected of a sex chromosome.

  16. First Description of the Karyotype and Sex Chromosomes in the Komodo Dragon (Varanus komodoensis).

    Science.gov (United States)

    Johnson Pokorná, Martina; Altmanová, Marie; Rovatsos, Michail; Velenský, Petr; Vodička, Roman; Rehák, Ivan; Kratochvíl, Lukáš

    2016-01-01

    The Komodo dragon (Varanus komodoensis) is the largest lizard in the world. Surprisingly, it has not yet been cytogenetically examined. Here, we present the very first description of its karyotype and sex chromosomes. The karyotype consists of 2n = 40 chromosomes, 16 macrochromosomes and 24 microchromosomes. Although the chromosome number is constant for all species of monitor lizards (family Varanidae) with the currently reported karyotype, variability in the morphology of the macrochromosomes has been previously documented within the group. We uncovered highly differentiated ZZ/ZW sex microchromosomes with a heterochromatic W chromosome in the Komodo dragon. Sex chromosomes have so far only been described in a few species of varanids including V. varius, the sister species to Komodo dragon, whose W chromosome is notably larger than that of the Komodo dragon. Accumulations of several microsatellite sequences in the W chromosome have recently been detected in 3 species of monitor lizards; however, these accumulations are absent from the W chromosome of the Komodo dragon. In conclusion, although varanids are rather conservative in karyotypes, their W chromosomes exhibit substantial variability at the sequence level, adding further evidence that degenerated sex chromosomes may represent the most dynamic genome part. © 2016 S. Karger AG, Basel.

  17. The role of sex chromosomes in mammalian germ cell differentiation: can the germ cells carrying X and Y chromosomes differentiate into fertile oocytes?

    Directory of Open Access Journals (Sweden)

    Teruko Taketo

    2015-06-01

    Full Text Available The sexual differentiation of germ cells into spermatozoa or oocytes is strictly regulated by their gonadal environment, testis or ovary, which is determined by the presence or absence of the Y chromosome, respectively. Hence, in normal mammalian development, male germ cells differentiate in the presence of X and Y chromosomes, and female germ cells do so in the presence of two X chromosomes. However, gonadal sex reversal occurs in humans as well as in other mammalian species, and the resultant XX males and XY females can lead healthy lives, except for a complete or partial loss of fertility. Germ cells carrying an abnormal set of sex chromosomes are efficiently eliminated by multilayered surveillance mechanisms in the testis, and also, though more variably, in the ovary. Studying the molecular basis for sex-specific responses to a set of sex chromosomes during gametogenesis will promote our understanding of meiotic processes contributing to the evolution of sex determining mechanisms. This review discusses the fate of germ cells carrying various sex chromosomal compositions in mouse models, the limitation of which may be overcome by recent successes in the differentiation of functional germ cells from embryonic stem cells under experimental conditions.

  18. The mechanisms underlying sexual differentiation of behavior and physiology in mammals and birds: relative contributions of sex steroids and sex chromosomes

    Directory of Open Access Journals (Sweden)

    Fumihiko eMaekawa

    2014-08-01

    Full Text Available From a classical viewpoint, sex-specific behavior and physiological functions as well as the brain structures of mammals such as rats and mice, have been thought to be influenced by perinatal sex steroids secreted by the gonads. Sex steroids have also been thought to affect the differentiation of the sex-typical behavior of a few members of the avian order Galliformes, including the Japanese quail and chickens, during their development in ovo. However, recent mammalian studies that focused on the artificial shuffling or knockout of the sex-determining gene, Sry, have revealed that sex chromosomal effects may be associated with particular types of sex-linked differences such as aggression levels, social interaction, and autoimmune diseases, independently of sex steroid-mediated effects. In addition, studies on naturally occurring, rare phenomena such as gynandromorphic birds and experimentally constructed chimeras in which the composition of sex chromosomes in the brain differs from that in the other parts of the body, indicated that sex chromosomes play certain direct roles in the sex-specific differentiation of the gonads and the brain. In this article, we review the relative contributions of sex steroids and sex chromosomes in the determination of brain functions related to sexual behavior and reproductive physiology in mammals and birds.

  19. Using RAD-seq to recognize sex-specific markers and sex chromosome systems.

    Science.gov (United States)

    Gamble, Tony

    2016-05-01

    Next-generation sequencing methods have initiated a revolution in molecular ecology and evolution (Tautz et al. ). Among the most impressive of these sequencing innovations is restriction site-associated DNA sequencing or RAD-seq (Baird et al. ; Andrews et al. ). RAD-seq uses the Illumina sequencing platform to sequence fragments of DNA cut by a specific restriction enzyme and can generate tens of thousands of molecular genetic markers for analysis. One of the many uses of RAD-seq data has been to identify sex-specific genetic markers, markers found in one sex but not the other (Baxter et al. ; Gamble & Zarkower ). Sex-specific markers are a powerful tool for biologists. At their most basic, they can be used to identify the sex of an individual via PCR. This is useful in cases where a species lacks obvious sexual dimorphism at some or all life history stages. For example, such tests have been important for studying sex differences in life history (Sheldon ; Mossman & Waser ), the management and breeding of endangered species (Taberlet et al. ; Griffiths & Tiwari ; Robertson et al. ) and sexing embryonic material (Hacker et al. ; Smith et al. ). Furthermore, sex-specific markers allow recognition of the sex chromosome system in cases where standard cytogenetic methods fail (Charlesworth & Mank ; Gamble & Zarkower ). Thus, species with male-specific markers have male heterogamety (XY) while species with female-specific markers have female heterogamety (ZW). In this issue, Fowler & Buonaccorsi () illustrate the ease by which RAD-seq data can generate sex-specific genetic markers in rockfish (Sebastes). Moreover, by examining RAD-seq data from two closely related rockfish species, Sebastes chrysomelas and Sebastes carnatus (Fig. ), Fowler & Buonaccorsi () uncover shared sex-specific markers and a conserved sex chromosome system. © 2016 John Wiley & Sons Ltd.

  20. Weird mammals provide insights into the evolution of mammalian sex chromosomes and dosage compensation.

    Science.gov (United States)

    Graves, Jennifer A Marshall

    2015-12-01

    The deep divergence of mammalian groups 166 and 190 million years ago (MYA) provide genetic variation to explore the evolution of DNA sequence, gene arrangement and regulation of gene expression in mammals. With encouragement from the founder of the field, Mary Lyon, techniques in cytogenetics and molecular biology were progressively adapted to characterize the sex chromosomes of kangaroos and other marsupials, platypus and echidna-and weird rodent species. Comparative gene mapping reveals the process of sex chromosome evolution from their inception 190 MYA (they are autosomal in platypus) to their inevitable end (the Y has disappeared in two rodent lineages). Our X and Y are relatively young, getting their start with the evolution of the sex-determining SRY gene, which triggered progressive degradation of the Y chromosome. Even more recently, sex chromosomes of placental mammals fused with an autosomal region which now makes up most of the Y. Exploration of gene activity patterns over four decades showed that dosage compensation via X-chromosome inactivation is unique to therian mammals, and that this whole chromosome control process is different in marsupials and absent in monotremes and reptiles, and birds. These differences can be exploited to deduce how mammalian sex chromosomes and epigenetic silencing evolved.

  1. Genetic Diversity in the UV Sex Chromosomes of the Brown Alga Ectocarpus.

    Science.gov (United States)

    Avia, Komlan; Lipinska, Agnieszka P; Mignerot, Laure; Montecinos, Alejandro E; Jamy, Mahwash; Ahmed, Sophia; Valero, Myriam; Peters, Akira F; Cock, J Mark; Roze, Denis; Coelho, Susana M

    2018-06-06

    Three types of sex chromosome system exist in nature: diploid XY and ZW systems and haploid UV systems. For many years, research has focused exclusively on XY and ZW systems, leaving UV chromosomes and haploid sex determination largely neglected. Here, we perform a detailed analysis of DNA sequence neutral diversity levels across the U and V sex chromosomes of the model brown alga Ectocarpus using a large population dataset. We show that the U and V non-recombining regions of the sex chromosomes (SDR) exhibit about half as much neutral diversity as the autosomes. This difference is consistent with the reduced effective population size of these regions compared with the rest of the genome, suggesting that the influence of additional factors such as background selection or selective sweeps is minimal. The pseudoautosomal region (PAR) of this UV system, in contrast, exhibited surprisingly high neutral diversity and there were several indications that genes in this region may be under balancing selection. The PAR of Ectocarpus is known to exhibit unusual genomic features and our results lay the foundation for further work aimed at understanding whether, and to what extent, these structural features underlie the high level of genetic diversity. Overall, this study fills a gap between available information on genetic diversity in XY/ZW systems and UV systems and significantly contributes to advancing our knowledge of the evolution of UV sex chromosomes.

  2. Structural, functional, and evolutionary features of plant sex chromosomes

    Czech Academy of Sciences Publication Activity Database

    Vyskot, Boris; Hobza, Roman; Kejnovský, Eduard; Žlůvová, Jitka; Janoušek, Bohuslav

    2009-01-01

    Roč. 17, č. 4 (2009), s. 547 ISSN 0967-3849. [17th International Chromosome Conference. 23.06.2009-26.06.2009, Boone] R&D Projects: GA MŠk(CZ) LC06004 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : sex chromosomes * Silene latifolia * epigenetic Subject RIV: BO - Biophysics

  3. Karyological characterization of the endemic Iberian rock lizard, Iberolacerta monticola (Squamata, Lacertidae): insights into sex chromosome evolution.

    Science.gov (United States)

    Rojo, V; Giovannotti, M; Naveira, H; Nisi Cerioni, P; González-Tizón, A M; Caputo Barucchi, V; Galán, P; Olmo, E; Martínez-Lage, A

    2014-01-01

    Rock lizards of the genus Iberolacerta constitute a promising model to examine the process of sex chromosome evolution, as these closely related taxa exhibit remarkable diversity in the degree of sex chromosome differentiation with no clear phylogenetic segregation, ranging from cryptic to highly heteromorphic ZW chromosomes and even multiple chromosome systems (Z1Z1Z2Z2/Z1Z2W). To gain a deeper insight into the patterns of karyotype and sex chromosome evolution, we performed a cytogenetic analysis based on conventional staining, banding techniques and fluorescence in situ hybridization in the species I. monticola, for which previous cytogenetic investigations did not detect differentiated sex chromosomes. The karyotype is composed of 2n = 36 acrocentric chromosomes. NORs and the major ribosomal genes were located in the subtelomeric region of chromosome pair 6. Hybridization signals of the telomeric sequences (TTAGGG)n were visualized at the telomeres of all chromosomes and interstitially in 5 chromosome pairs. C-banding showed constitutive heterochromatin at the centromeres of all chromosomes, as well as clear pericentromeric and light telomeric C-bands in several chromosome pairs. These results highlight some chromosomal markers which can be useful to identify species-specific diagnostic characters, although they may not accurately reflect the phylogenetic relationships among the taxa. In addition, C-banding revealed the presence of a heteromorphic ZW sex chromosome pair, where W is smaller than Z and almost completely heterochromatic. This finding sheds light on sex chromosome evolution in the genus Iberolacerta and suggests that further comparative cytogenetic analyses are needed to understand the processes underlying the origin, differentiation and plasticity of sex chromosome systems in lacertid lizards. © 2013 S. Karger AG, Basel.

  4. [Identification of the genetic sex chromosomes in the monogenic blowfly Chrysomya rufifacies (Calliphoridae, Diptera)].

    Science.gov (United States)

    Ullerich, F H

    1975-01-01

    Previous investigations have shown the sex determination in the monogenic blowfly Chrysomya rufifacies to be controlled by a cytologically not discernible homogametry-heterogamety mechanism in the female. Female-producing (thelygenic) females are assumed to be heterozygous for a dominant female sex realizer (F') with sex-predetermining properties, while male-producing (arrhenogenic) females as well as males are supposed to be homozygous for the recessive allele (f). In order to identify the genetic sex chromosomes of C. rufifacies among its five pairs of long euchromatic chromosomes (nos. 1-5) plus one pair of small heterochromatic ones (no. 6), all chromosomes were marked by reciprocal translocations induced by X-ray treatment of adult males. The inheritance of thirteen different heteroxygous translocations has been analyzed. All of the translocations (eleven) between two of the four longer chromosomes did not show sex-linked inheritance, thus demonstrating the autosomal character of the chromosomes nos 1, 2, 3 and 4. The same is true for the translocation T6 (2/6). Therefore the small heterochromatic chromosome no. 6, corresponding to the morphlogically differentiated six chromosomes within the amphogenic calliphorid species, remains without sex determining function in the monogenic fly. This could be confirmed by the analysis of monosomic (monosomy-6) and trisomic (trisomy-6) individuals, which resulted from meiotic non-disfunction in T6/+ translocation heterozygotes. Contrary to these translocations, the heteroxygous 5/2 translocation (T14) exhibited sex-linked inheritance: There was but a very low frequency (0,76 per cent) of recombinants resulting from crossing-over between F'/f and the translocation breakage point in theylgenic F1 T14/+females. The sex-linked inheritance of T14 was confirmed by the progeny of a thelygenic F1 T14/+ female crossed to a homozygous T14/T14 translocation male.Among the offspring of that F1 T14/+ female, which had received the

  5. Exposure to persistent organic pollutants and sperm sex chromosome ratio in men from the Faroe Islands

    DEFF Research Database (Denmark)

    Kvist, L; Giwercman, A; Weihe, P

    2014-01-01

    People in the Arctic as well as fishermen on the polluted Swedish east coast are highly exposed to persistent organic pollutants (POPs). These compounds have been shown to affect the sperm Y:X chromosome ratio. In present study, the aim was to investigate whether polychlorinated biphenyl (PCB......,p'-DDE and ΣPCB correlated significantly (r=0.927, pboth Inuit and Swedish fishermen (0.512 for both......). In conclusion, Faroese men presented with lower Y:X ratio than Greenland Inuit and Swedish fishermen. Although no direct health effects are expected due to the lower Faroese Y:X ratio, it could be indicative of adverse effects on the reproductive system....

  6. Chromosomal Evolution in Lower Vertebrates: Sex Chromosomes in Neotropical Fishes

    Czech Academy of Sciences Publication Activity Database

    Cioffi, M. de B.; Yano, C. F.; Sember, Alexandr; Bertollo, L.A.C.

    2017-01-01

    Roč. 8, č. 10 (2017), č. článku 258. ISSN 2073-4425 R&D Projects: GA MŠk EF15_003/0000460 Institutional support: RVO:67985904 Keywords : alternative evolutionary models * simple and multiple sex chromosomes * independent and common origins Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 3.600, year: 2016

  7. Live birth sex ratios and father’s geographic origins in Jerusalem, 1964–1976

    Science.gov (United States)

    Groeger, J; Opler, M; Kleinhaus, K; Perrin, MC; Calderon-Margalit, R; Manor, O; Paltiel, O; Conley, D; Harlap, S; Malaspina, D

    2016-01-01

    Objective To examine whether ancestry influenced sex ratios of offspring in a birth cohort before parental antenatal sex selection influenced offspring sex. Methods We measured the sex ratio as the percent of males according to countries of birth of paternal and maternal grandfathers in 91,459 live births from 1964 to 1976 in the Jerusalem Perinatal Study. Confidence limits (CI) were computed based on an expected sex ratio of 1.05, which is 51.4% male. Results Of all live births recorded, 51.4% were male. Relative to Jewish ancestry (51.4% males), significantly more males (1,761) were born to Muslim ancestry (54.5, 95% CI=52.1–56.8, p=.01). Among the former, sex ratios were not significantly associated with paternal or maternal age, education, or offspring’s birth order. Consistent with a preference for male offspring, the sex ratio decreased despite increasing numbers of births over the 13-year period. Sex ratios were not affected by maternal or paternal origins in North Africa or Europe. However, the offspring whose paternal grandfathers were born in Western Asia included fewer males than expected (50.7, 50.1–51.3, p=.02), whether the father was born abroad (50.7) or in Israel (50.8). This was observed for descendents of paternal grandfathers born in Lebanon (47.6), Turkey (49.9), Yemen & Aden (50.2), Iraq (50.5), Afghanistan (50.5), Syria (50.6), and Cyprus (50.7); but not for those from India (51.5) or Iran (51.9). The West Asian group showed the strongest decline in sex ratios with increasing paternal family size. Conclusions A decreased sex ratio associated with ancestry in Western Asia is consistent with reduced ability to bear sons by a subset of Jewish men in the Jerusalem cohort. Lower sex ratios may be due to pregnancy stress, which may be higher in this subgroup. Alternatively, a degrading Y chromosome haplogroup or other genetic or epigenetic differences on male germ lines could affect birth ratios, such as differential exposure to an

  8. Establishment of a 10-Plex Quantitative Fluorescent-PCR Assay for rapid diagnosis of sex chromosome aneuploidies.

    Directory of Open Access Journals (Sweden)

    Xingmei Xie

    Full Text Available Sex chromosome aneuploidies occur commonly in the general population, with an incidence of 1 in 400 newborns. However, no tests specifically targeting sex chromosomes have been carried out in prenatal diagnosis or newborn screening, resulting in late recognition of these diseases. In this study, a rapid diagnostic method for sex chromosome aneuploidies was established using Quantitative Fluorescent-PCR (QF-PCR. Ten markers were included in one multiplex QF-PCR assay, including two sex determination genes (AMXY and SRY, five X-linked short tandem repeats (STRs; DXS1053, DXS981, DXS6809, DXS1187, and DXS8377, one X/Y-common STR (X22, and two autosomal STRs (D13S305 and D21S11. Retrospective tests of 70 cases with known cytogenetic results indicated that the 10-plex QF-PCR assay could well determine sex chromosome copy numbers by both allelic peak numbers and a sex chromosome dosage calculation with the autosomal STRs as internal controls. Prospective comparison with cytogenetic karyotyping on 534 cases confirmed that the 10-plex QF-PCR assay could be well employed for sex chromosome aneuploidy diagnosis in at least the Chinese Han population. This is the first QF-PCR test for the diagnosis of sex chromosome aneuploidies in the Chinese population. This test is superior to previous designs by including up to 8 sex-linked markers covering different parts of sex chromosomes as well as employing internal controls for copy number dosage calculation in a single PCR reaction. Due to simple technique and data analysis, as well as easy implementation within routine clinical services, this method is of great clinical application value and could be widely applied.

  9. Effect of gamma irradiation on sex chromatin body appearance and the sex chromosome aberrations in the potato tuber moth, phthorimaea operculella (Lepidoptera: Gelechiidae)

    International Nuclear Information System (INIS)

    Makee, H.

    2007-01-01

    Genetic sexing technique based on the construction of a Balanced Lethal Strain (BLS) has been proposed for Phthorimaea operculella (Zeller). The isolation of female with T(W. Z) translocation is a fundamental step to develop such strain. Gamma irradiation was used to induce the requested translocations. The availability of sex-linked morphological marker is required to facilitate the detection of such mutations. Since a visible sex-linked marker has not been found in P. operculella, therefore main aim of our study was to determine the possibility of using sex heterochromatin body as a marker to identify the required translocated females. The appearance of sex heterochromatin body and the analysis of sex chromosomes in F1 females of irradiated P. operculella females were investigated. The percentage of abnormality in sex heterochromatin body in highly polyploid Malpighian tubule nuclei was increased by increasing the applied dose. Based on the appearance of this body, 3 mutant lines were isolated: elongated, small, fragmented lines. W chromosome was easily distinguished from Z chromosome when the analysis of pachytene sex chromosome bivalents of P. operculella females was carried out. The aberrations involved W chromosome directly influenced the appearance of sex heterochromatin body in highly polyploid somatic cells of the isolated mutant lines. The results showed that sex heterochromatin could be used as sex determination and cytogenetic marker in P. operculella. (Author)

  10. Effect of gamma irradiation on sex chromatin body appearance and the sex chromosome aberrations in the potato tuber moth, phthorimaea operculella (Lepidoptera: Gelechiidae)

    International Nuclear Information System (INIS)

    Makee, H.

    2006-05-01

    Genetic sexing technique based on the construction of a Balanced Lethal Strain (BLS) has been proposed for Phthorimaea operculella (Zeller). The isolation of female with T(W; Z) translocation is a fundamental step to develop such strain. Gamma irradiation was used to induce the requested translocations. The availability of sex-linked morphological marker is required to facilitate the detection of such mutations. Since a visible sex-linked marker has not been found in P. operculella, therefore main aim of our study was to determine the possibility of using sex heterochromatin body as a marker to identify the required translocated females. The appearance of sex heterochromatin body and the analysis of sex chromosomes in F1 females of irradiated P. operculella females were investigated. The percentage of abnormality in sex heterochromatin body in highly polyploid Malpighian tubule nuclei was increased by increasing the applied dose. Based on the appearance of this body, 3 mutant lines were isolated: elongated, small, fragmented lines. W chromosome was easily distinguished from Z chromosome when the analysis of pachytene sex chromosome bivalents of P. operculella females was carried out. The aberrations involved W chromosome directly influenced the appearance of sex heterochromatin body in highly polyploid somatic cells of the isolated mutant lines. The results showed that sex heterochromatin could be used as sex determination and cytogenetic marker in P. operculella. (Author)

  11. Convergent evolution of chromosomal sex-determining regions in the animal and fungal kingdoms.

    Directory of Open Access Journals (Sweden)

    James A Fraser

    2004-12-01

    Full Text Available Sexual identity is governed by sex chromosomes in plants and animals, and by mating type (MAT loci in fungi. Comparative analysis of the MAT locus from a species cluster of the human fungal pathogen Cryptococcus revealed sequential evolutionary events that fashioned this large, highly unusual region. We hypothesize that MAT evolved via four main steps, beginning with acquisition of genes into two unlinked sex-determining regions, forming independent gene clusters that then fused via chromosomal translocation. A transitional tripolar intermediate state then converted to a bipolar system via gene conversion or recombination between the linked and unlinked sex-determining regions. MAT was subsequently subjected to intra- and interallelic gene conversion and inversions that suppress recombination. These events resemble those that shaped mammalian sex chromosomes, illustrating convergent evolution in sex-determining structures in the animal and fungal kingdoms.

  12. Sex ratio meiotic drive as a plausible evolutionary mechanism for hybrid male sterility.

    Science.gov (United States)

    Zhang, Linbin; Sun, Tianai; Woldesellassie, Fitsum; Xiao, Hailian; Tao, Yun

    2015-03-01

    Biological diversity on Earth depends on the multiplication of species or speciation, which is the evolution of reproductive isolation such as hybrid sterility between two new species. An unsolved puzzle is the exact mechanism(s) that causes two genomes to diverge from their common ancestor so that some divergent genes no longer function properly in the hybrids. Here we report genetic analyses of divergent genes controlling male fertility and sex ratio in two very young fruitfly species, Drosophila albomicans and D. nasuta. A majority of the genetic divergence for both traits is mapped to the same regions by quantitative trait loci mappings. With introgressions, six major loci are found to contribute to both traits. This genetic colocalization implicates that genes for hybrid male sterility have evolved primarily for controlling sex ratio. We propose that genetic conflicts over sex ratio may operate as a perpetual dynamo for genome divergence. This particular evolutionary mechanism may largely contribute to the rapid evolution of hybrid male sterility and the disproportionate enrichment of its underlying genes on the X chromosome--two patterns widely observed across animals.

  13. Asymmetry of cerebral grey and white matter and structural volumes in relation to sex hormones and chromosomes

    Directory of Open Access Journals (Sweden)

    Ivanka eSavic

    2014-11-01

    Full Text Available Whilst many studies show sex differences in cerebral asymmetry, their mechanisms are still unknown. This report describes the potential impact of sex hormones and sex chromosomes by comparing MR data from 39 male and 47 female controls and 33 men with an extra X-chromosome (47,XXY Methods: Regional asymmetry in grey and white matter volumes (GMV and WMV was calculated using voxel based moprhometry (SPM5, by contrasting the unflipped and flipped individual GMV and WMV images. In addition, structural volumes were calculated for the thalamus, caudate, putamen, amygdala, and hippocampus, using the FreeSurfer software. Effects of plasma testosterone and estrogen on the GMV and WMV, as well on the right/left ratios of the subcortical volumes were tested by multi-regression analysis.Results: All three groups showed a leftward asymmetry in the motor cortex and the planum temporale, and a rightward asymmetry of the middle occipital cortex. Both asymmetries were more pronounced in 46,XY males than 46,XX females and 47,XXY males, and were positively correlated with testosterone levels. There was also a rightward asymmetry of the vermis and leftward asymmetry in the cerebellar hemispheres in all groups. Notably, cerebellar asymmetries were larger in 46,XX females and 47,XXY males, but were not related to sex hormone levels. No asymmetry differences between 46,XX females and 47,XXY males, and no overall effects of brain size were detected.Conclusion: The asymmetry in the planum temporale area and the occipital cortex seem related to processes associated with testosterone, whereas the observed cerebellar asymmetries suggest a link with X-chromosome escapee genes. Sex differences in cerebral asymmetry are moderated by sex hormones and X-chromosome genes, in a regionally differentiated manner.

  14. Asymmetry of cerebral gray and white matter and structural volumes in relation to sex hormones and chromosomes.

    Science.gov (United States)

    Savic, Ivanka

    2014-01-01

    Whilst many studies show sex differences in cerebral asymmetry, their mechanisms are still unknown. This report describes the potential impact of sex hormones and sex chromosomes by comparing MR data from 39 male and 47 female controls and 33 men with an extra X-chromosome (47,XXY). Regional asymmetry in gray and white matter volumes (GMV and WMV) was calculated using voxel based moprhometry (SPM5), by contrasting the unflipped and flipped individual GMV and WMV images. In addition, structural volumes were calculated for the thalamus, caudate, putamen, amygdala, and hippocampus, using the FreeSurfer software. Effects of plasma testosterone and estrogen on the GMV and WMV, as well on the right/left ratios of the subcortical volumes were tested by multi-regression analysis. All three groups showed a leftward asymmetry in the motor cortex and the planum temporale, and a rightward asymmetry of the middle occipital cortex. Both asymmetries were more pronounced in 46,XY males than 46,XX females and 47,XXY males, and were positively correlated with testosterone levels. There was also a rightward asymmetry of the vermis and leftward GMV asymmetry in the cerebellar hemispheres in all groups. Notably, cerebellar asymmetries were larger in 46,XX females and 47,XXY males, but were not related to sex hormone levels. No asymmetry differences between 46,XX females and 47,XXY males, and no overall effects of brain size were detected. The asymmetry in the planum temporale area and the occipital cortex seem related to processes associated with testosterone, whereas the observed cerebellar asymmetries suggest a link with X-chromosome escapee genes. Sex differences in cerebral asymmetry are moderated by sex hormones and X-chromosome genes, in a regionally differentiated manner.

  15. The XX sex chromosome complement in mice is associated with increased spontaneous lupus compared with XY.

    Science.gov (United States)

    Sasidhar, Manda V; Itoh, Noriko; Gold, Stefan M; Lawson, Gregory W; Voskuhl, Rhonda R

    2012-08-01

    Many autoimmune diseases are characterised by a female predominance. This may be caused by sex hormones, sex chromosomes or both. This report uses a transgenic mouse model to investigate how sex chromosome complement, not confounded by differences in gonadal type, might contribute to lupus pathogenesis. Transgenic NZM2328 mice were created by deletion of the Sry gene from the Y chromosome, thereby separating genetic from gonadal sex. Survival, renal histopathology and markers of immune activation were compared in mice carrying the XX versus the XY(-) sex chromosome complement, with each genotype being ovary bearing. Mice with XX sex chromosome complement compared with XY(-) exhibited poorer survival rates and increased kidney pathology. Splenic T lymphocytes from XX mice demonstrated upregulated X-linked CD40 ligand expression and higher levels of activation markers ex vivo. Increased MMP, TGF and IL-13 production was found, while IL-2 was lower in XX mice. An accumulation of splenic follicular B cells and peritoneal marginal zone B cells was observed, coupled with upregulated costimulatory marker expression on B cells in XX mice. These data show that the XX sex chromosome complement, compared with XY(-), is associated with accelerated spontaneous lupus.

  16. Haldane’s Rule Is Linked to Extraordinary Sex Ratios and Sperm Length in Stalk-Eyed Flies

    Science.gov (United States)

    Wilkinson, Gerald S.; Christianson, Sarah J.; Brand, Cara L.; Ru, George; Shell, Wyatt

    2014-01-01

    We use three allopatric populations of the stalk-eyed fly Teleopsis dalmanni from Southeast Asia to test two predictions made by the sex chromosome drive hypothesis for Haldane’s rule. The first is that modifiers that suppress or enhance drive should evolve rapidly and independently in isolated populations. The second is that drive loci or modifiers should also cause sterility in hybrid males. We tested these predictions by assaying the fertility of 2066 males derived from backcross experiments involving two pairs of populations and found that the proportion of mated males that fail to produce any offspring ranged from 38 to 60% among crosses with some males producing strongly female-biased or male-biased sex ratios. After genotyping each male at 25–28 genetic markers we found quantitative trait loci (QTL) that jointly influence male sterility, sperm length, and biased progeny sex ratios in each pair of populations, but almost no shared QTL between population crosses. We also discovered that the extant XSR chromosome has no effect on sex ratio or sterility in these backcross males. Whether shared QTL are caused by linkage or pleiotropy requires additional study. Nevertheless, these results indicate the presence of a “cryptic” drive system that is currently masked by suppressing elements that are associated with sterility and sperm length within but not between populations and, therefore, must have evolved since the populations became isolated, i.e., in hybrid sterility. PMID:25164880

  17. Molecular cytogenetic characterization of the dioecious Cannabis sativa with an XY chromosome sex determination system.

    Science.gov (United States)

    Divashuk, Mikhail G; Alexandrov, Oleg S; Razumova, Olga V; Kirov, Ilya V; Karlov, Gennady I

    2014-01-01

    Hemp (Cannabis sativa L.) was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71), 5S rDNA (pCT4.2), a subtelomeric repeat (CS-1) and the Arabidopsis telomere probes. The karyotype has 18 autosomes plus a sex chromosome pair (XX in female and XY in male plants). The autosomes are difficult to distinguish morphologically, but three pairs could be distinguished using the probes. The Y chromosome is larger than the autosomes, and carries a fully heterochromatic DAPI positive arm and CS-1 repeats only on the less intensely DAPI-stained, euchromatic arm. The X is the largest chromosome of all, and carries CS-1 subtelomeric repeats on both arms. The meiotic configuration of the sex bivalent locates a pseudoautosomal region of the Y chromosome at the end of the euchromatic CS-1-carrying arm. Our molecular cytogenetic study of the C. sativa sex chromosomes is a starting point for helping to make C. sativa a promising model to study sex chromosome evolution.

  18. Chromosome analysis of arsenic affected cattle

    Directory of Open Access Journals (Sweden)

    S. Shekhar

    2014-10-01

    Full Text Available Aim: The aim was to study the chromosome analysis of arsenic affected cattle. Materials and Methods: 27 female cattle (21 arsenic affected and 6 normal were selected for cytogenetical study. The blood samples were collected, incubated, and cultured using appropriate media and specific methods. The samples were analyzed for chromosome number and morphology, relative length of the chromosome, arm ratio, and centromere index of X chromosome and chromosomal abnormalities in arsenic affected cattle to that of normal ones. Results: The diploid number of metaphase chromosomes in arsenic affected cattle as well as in normal cattle were all 2n=60, 58 being autosomes and 2 being sex chromosomes. From the centromeric position, karyotyping studies revealed that all the 29 pair of autosomes was found to be acrocentric or telocentric, and the sex chromosomes (XX were submetacentric in both normal and arsenic affected cattle. The relative length of all the autosome pairs and sex chrosomosome pair was found to be higher in normal than that of arsenic affected cattle. The mean arm ratio of X-chromosome was higher in normal than that of arsenic affected cattle, but it is reverse in case of centromere index value of X-chromosome. There was no significant difference of arm ratio and centromere index of X-chromosomes between arsenic affected and normal cattle. No chromosomal abnormalities were found in arsenic affected cattle. Conclusion: The chromosome analysis of arsenic affected cattle in West Bengal reported for the first time in this present study which may serve as a guideline for future studies in other species. These reference values will also help in comparison of cytological studies of arsenic affected cattle to that of various toxicants.

  19. Sex differences in circadian food anticipatory activity are not altered by individual manipulations of sex hormones or sex chromosome copy number in mice.

    Science.gov (United States)

    Aguayo, Antonio; Martin, Camille S; Huddy, Timothy F; Ogawa-Okada, Maya; Adkins, Jamie L; Steele, Andrew D

    2018-01-01

    Recent studies in mice have demonstrated a sexual dimorphism in circadian entrainment to scheduled feeding. On a time restricted diet, males tend to develop food anticipatory activity (FAA) sooner than females and with a higher amplitude of activity. The underlying cause of this sex difference remains unknown. One study suggests that sex hormones, both androgens and estrogens, modulate food anticipatory activity in mice. Here we present results suggesting that the sex difference in FAA is unrelated to gonadal sex hormones. While a sex difference between males and females in FAA on a timed, calorie restricted diet was observed there were no differences between intact and gonadectomized mice in the onset or magnitude of FAA. To test other sources of the sex difference in circadian entrainment to scheduled feeding, we used sex chromosome copy number mutants, but there was no difference in FAA when comparing XX, XY-, XY-;Sry Tg, and XX;Sry Tg mice, demonstrating that gene dosage of sex chromosomes does not mediate the sex difference in FAA. Next, we masculinized female mice by treating them with 17-beta estradiol during the neonatal period; yet again, we saw no difference in FAA between control and masculinized females. Finally, we observed that there was no longer a sex difference in FAA for older mice, suggesting that the sex difference in FAA is age-dependent. Thus, our study demonstrates that singular manipulations of gonadal hormones, sex chromosomes, or developmental patterning are not able to explain the difference in FAA between young male and female mice.

  20. Increased number of sex chromosomes affects height in a nonlinear fashion: a study of 305 patients with sex chromosome aneuploidy

    DEFF Research Database (Denmark)

    Ottesen, Anne-Marie; Aksglaede, Lise; Garn, Inger

    2010-01-01

    Tall stature and eunuchoid body proportions characterize patients with 47,XXY Klinefelter syndrome, whereas patients with 45,X Turner syndrome are characterized by impaired growth. Growth is relatively well characterized in these two syndromes, while few studies describe the growth of patients wi......,XXXX (n = 13), and -1.0 (-3.5 to -0.8) in 49,XXXXX (n = 3). Height increased with an increasing number of extra X or Y chromosomes, except in males with five, and in females with four or five sex chromosomes, consistent with a nonlinear effect on height....

  1. The mating-type chromosome in the filamentous ascomycete Neurospora tetrasperma represents a model for early evolution of sex chromosomes.

    Directory of Open Access Journals (Sweden)

    Audrius Menkis

    2008-03-01

    Full Text Available We combined gene divergence data, classical genetics, and phylogenetics to study the evolution of the mating-type chromosome in the filamentous ascomycete Neurospora tetrasperma. In this species, a large non-recombining region of the mating-type chromosome is associated with a unique fungal life cycle where self-fertility is enforced by maintenance of a constant state of heterokaryosis. Sequence divergence between alleles of 35 genes from the two single mating-type component strains (i.e. the homokaryotic mat A or mat a-strains, derived from one N. tetrasperma heterokaryon (mat A+mat a, was analyzed. By this approach we were able to identify the boundaries and size of the non-recombining region, and reveal insight into the history of recombination cessation. The non-recombining region covers almost 7 Mbp, over 75% of the chromosome, and we hypothesize that the evolution of the mating-type chromosome in this lineage involved two successive events. The first event was contemporaneous with the split of N. tetrasperma from a common ancestor with its outcrossing relative N. crassa and suppressed recombination over at least 6.6 Mbp, and the second was confined to a smaller region in which recombination ceased more recently. In spite of the early origin of the first "evolutionary stratum", genealogies of five genes from strains belonging to an additional N. tetrasperma lineage indicate independent initiations of suppressed recombination in different phylogenetic lineages. This study highlights the shared features between the sex chromosomes found in the animal and plant kingdoms and the fungal mating-type chromosome, despite fungi having no separate sexes. As is often found in sex chromosomes of plants and animals, recombination suppression of the mating-type chromosome of N. tetrasperma involved more than one evolutionary event, covers the majority of the mating-type chromosome and is flanked by distal regions with obligate crossovers.

  2. Molecular cytogenetic characterization of the dioecious Cannabis sativa with an XY chromosome sex determination system.

    Directory of Open Access Journals (Sweden)

    Mikhail G Divashuk

    Full Text Available Hemp (Cannabis sativa L. was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71, 5S rDNA (pCT4.2, a subtelomeric repeat (CS-1 and the Arabidopsis telomere probes. The karyotype has 18 autosomes plus a sex chromosome pair (XX in female and XY in male plants. The autosomes are difficult to distinguish morphologically, but three pairs could be distinguished using the probes. The Y chromosome is larger than the autosomes, and carries a fully heterochromatic DAPI positive arm and CS-1 repeats only on the less intensely DAPI-stained, euchromatic arm. The X is the largest chromosome of all, and carries CS-1 subtelomeric repeats on both arms. The meiotic configuration of the sex bivalent locates a pseudoautosomal region of the Y chromosome at the end of the euchromatic CS-1-carrying arm. Our molecular cytogenetic study of the C. sativa sex chromosomes is a starting point for helping to make C. sativa a promising model to study sex chromosome evolution.

  3. Seed sexing revealed female bias in two Rumex species

    Directory of Open Access Journals (Sweden)

    Dagmara Kwolek

    2011-07-01

    Full Text Available Sex-ratio bias in seeds of dioecious Rumex species with sex chromosomes is an interesting and still unsettled issue. To resolve gender among seeds of R. acetosa and R. thyrsiflorus (two species with an XX/XY1Y2 sex chromosome system, this work applied a PCR-based method involving DNA markers located on Y chromosomes. Both species showed female-biased primary sex ratios, with female bias greater in R. acetosa than in R. thyrsiflorus. The observed predominance of female seeds is consistent with the view that the female biased sex ratios in Rumex are conditioned not only postzygotically but also prezygotically.

  4. Caenorhabditis elegans histone methyltransferase MET-2 shields the male X chromosome from checkpoint machinery and mediates meiotic sex chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Paula M Checchi

    2011-09-01

    Full Text Available Meiosis is a specialized form of cellular division that results in the precise halving of the genome to produce gametes for sexual reproduction. Checkpoints function during meiosis to detect errors and subsequently to activate a signaling cascade that prevents the formation of aneuploid gametes. Indeed, asynapsis of a homologous chromosome pair elicits a checkpoint response that can in turn trigger germline apoptosis. In a heterogametic germ line, however, sex chromosomes proceed through meiosis with unsynapsed regions and are not recognized by checkpoint machinery. We conducted a directed RNAi screen in Caenorhabditis elegans to identify regulatory factors that prevent recognition of heteromorphic sex chromosomes as unpaired and uncovered a role for the SET domain histone H3 lysine 9 histone methyltransferase (HMTase MET-2 and two additional HMTases in shielding the male X from checkpoint machinery. We found that MET-2 also mediates the transcriptional silencing program of meiotic sex chromosome inactivation (MSCI but not meiotic silencing of unsynapsed chromatin (MSUC, suggesting that these processes are distinct. Further, MSCI and checkpoint shielding can be uncoupled, as double-strand breaks targeted to an unpaired, transcriptionally silenced extra-chromosomal array induce checkpoint activation in germ lines depleted for met-2. In summary, our data uncover a mechanism by which repressive chromatin architecture enables checkpoint proteins to distinguish between the partnerless male X chromosome and asynapsed chromosomes thereby shielding the lone X from inappropriate activation of an apoptotic program.

  5. Sex chromosome-specific regulation in the Drosophila male germline but little evidence for chromosomal dosage compensation or meiotic inactivation.

    Directory of Open Access Journals (Sweden)

    Colin D Meiklejohn

    2011-08-01

    Full Text Available The evolution of heteromorphic sex chromosomes (e.g., XY in males or ZW in females has repeatedly elicited the evolution of two kinds of chromosome-specific regulation: dosage compensation--the equalization of X chromosome gene expression in males and females--and meiotic sex chromosome inactivation (MSCI--the transcriptional silencing and heterochromatinization of the X during meiosis in the male (or Z in the female germline. How the X chromosome is regulated in the Drosophila melanogaster male germline is unclear. Here we report three new findings concerning gene expression from the X in Drosophila testes. First, X chromosome-wide dosage compensation appears to be absent from most of the Drosophila male germline. Second, microarray analysis provides no evidence for X chromosome-specific inactivation during meiosis. Third, we confirm the previous discovery that the expression of transgene reporters driven by autosomal spermatogenesis-specific promoters is strongly reduced when inserted on the X chromosome versus the autosomes; but we show that this chromosomal difference in expression is established in premeiotic cells and persists in meiotic cells. The magnitude of the X-autosome difference in transgene expression cannot be explained by the absence of dosage compensation, suggesting that a previously unrecognized mechanism limits expression from the X during spermatogenesis in Drosophila. These findings help to resolve several previously conflicting reports and have implications for patterns of genome evolution and speciation in Drosophila.

  6. Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans

    Directory of Open Access Journals (Sweden)

    Zhou Qi

    2012-03-01

    Full Text Available Abstract Background Drosophila albomicans is a unique model organism for studying both sex chromosome and B chromosome evolution. A pair of its autosomes comprising roughly 40% of the whole genome has fused to the ancient X and Y chromosomes only about 0.12 million years ago, thereby creating the youngest and most gene-rich neo-sex system reported to date. This species also possesses recently derived B chromosomes that show non-Mendelian inheritance and significantly influence fertility. Methods We sequenced male flies with B chromosomes at 124.5-fold genome coverage using next-generation sequencing. To characterize neo-Y specific changes and B chromosome sequences, we also sequenced inbred female flies derived from the same strain but without B's at 28.5-fold. Results We assembled a female genome and placed 53% of the sequence and 85% of the annotated proteins into specific chromosomes, by comparison with the 12 Drosophila genomes. Despite its very recent origin, the non-recombining neo-Y chromosome shows various signs of degeneration, including a significant enrichment of non-functional genes compared to the neo-X, and an excess of tandem duplications relative to other chromosomes. We also characterized a B-chromosome linked scaffold that contains an actively transcribed unit and shows sequence similarity to the subcentromeric regions of both the ancient X and the neo-X chromosome. Conclusions Our results provide novel insights into the very early stages of sex chromosome evolution and B chromosome origination, and suggest an unprecedented connection between the births of these two systems in D. albomicans.

  7. Sex chromosome differentiation and the W- and Z-specific loci in Xenopus laevis.

    Science.gov (United States)

    Mawaribuchi, Shuuji; Takahashi, Shuji; Wada, Mikako; Uno, Yoshinobu; Matsuda, Yoichi; Kondo, Mariko; Fukui, Akimasa; Takamatsu, Nobuhiko; Taira, Masanori; Ito, Michihiko

    2017-06-15

    Genetic sex-determining systems in vertebrates include two basic types of heterogamety; XX (female)/XY (male) and ZZ (male)/ZW (female) types. The African clawed frog Xenopus laevis has a ZZ/ZW-type sex-determining system. In this species, we previously identified a W-specific sex (female)-determining gene dmw, and specified W and Z chromosomes, which could be morphologically indistinguishable (homomorphic). In addition to dmw, we most recently discovered two genes, named scanw and ccdc69w, and one gene, named capn5z in the W- and Z-specific regions, respectively. In this study, we revealed the detail structures of the W/Z-specific loci and genes. Sequence analysis indicated that there is almost no sequence similarity between 278kb W-specific and 83kb Z-specific sequences on chromosome 2Lq32-33, where both the transposable elements are abundant. Synteny and phylogenic analyses indicated that all the W/Z-specific genes might have emerged independently. Expression analysis demonstrated that scanw and ccdc69w or capn5z are expressed in early differentiating ZW gonads or testes, thereby suggesting possible roles in female or male development, respectively. Importantly, the sex-determining gene (SDG) dmw might have been generated after allotetraploidization, thereby indicating the construction of the new sex-determining system by dmw after species hybridization. Furthermore, by direct genotyping, we confirmed that diploid WW embryos developed into normal female frogs, which indicate that the Z-specific region is not essential for female development. Overall, these findings indicate that sex chromosome differentiation has started, although no heteromorphic sex chromosomes are evident yet, in X. laevis. Homologous recombination suppression might have promoted the accumulation of mutations and transposable elements, and enlarged the W/Z-specific regions, thereby resulting in differentiation of the W/Z chromosomes. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Sex ratio meiotic drive as a plausible evolutionary mechanism for hybrid male sterility.

    Directory of Open Access Journals (Sweden)

    Linbin Zhang

    2015-03-01

    Full Text Available Biological diversity on Earth depends on the multiplication of species or speciation, which is the evolution of reproductive isolation such as hybrid sterility between two new species. An unsolved puzzle is the exact mechanism(s that causes two genomes to diverge from their common ancestor so that some divergent genes no longer function properly in the hybrids. Here we report genetic analyses of divergent genes controlling male fertility and sex ratio in two very young fruitfly species, Drosophila albomicans and D. nasuta. A majority of the genetic divergence for both traits is mapped to the same regions by quantitative trait loci mappings. With introgressions, six major loci are found to contribute to both traits. This genetic colocalization implicates that genes for hybrid male sterility have evolved primarily for controlling sex ratio. We propose that genetic conflicts over sex ratio may operate as a perpetual dynamo for genome divergence. This particular evolutionary mechanism may largely contribute to the rapid evolution of hybrid male sterility and the disproportionate enrichment of its underlying genes on the X chromosome--two patterns widely observed across animals.

  9. Could changes in reported sex ratios at birth during China's 1958-1961 famine support the adaptive sex ratio adjustment hypothesis?

    Directory of Open Access Journals (Sweden)

    Anna Reimondos

    2013-10-01

    Full Text Available Background: The adaptive sex ratio adjustment hypothesis suggests that when mothers are in poor conditions the sex ratio of their offspring will be biased towards females. Major famines provide opportunities for testing this hypothesis because they lead to the widespread deterioration of living conditions in the affected population. Objective: This study examines changes in sex ratio at birth before, during, and after China's 1958-1961 famine, to see whether they provide any support for the adaptive sex ratio adjustment hypothesis. Methods: We use descriptive statistics to analyse data collected by both China's 1982 and 1988 fertility sample surveys and examine changes in sex ratio at birth in recent history. In addition, we examine the effectiveness of using different methods to model changes in sex ratio at birth and compare their differences. Results: During China's 1958-1961 famine, reported sex ratio at birth remained notably higher than that observed in most countries in the world. The timing of the decline in sex ratio at birth did not coincide with the timing of the famine. After the famine, although living conditions were considerably improved, the sex ratio at birth was not higher but lower than that recorded during the famine. Conclusions: The analysis of the data collected by the two fertility surveys has found no evidence that changes in sex ratio at birth during China's 1958-1961 famine and the post-famine period supported the adaptive sex ratio adjustment hypothesis.

  10. Human male infertility, the Y chromosome, and dinosaur extinction

    Directory of Open Access Journals (Sweden)

    Sherman J. Silber

    2011-06-01

    Our studies of the Y chromosome and male infertility suggest that the default mechanism for determining the sex of offspring is the temperature of egg incubation, and that genetic sex determination (based on sex chromosomes like X and Y has evolved many times over and over again in different ways, in different genera, as a more foolproof method than temperature variation of assuring a balanced sex ratio in offspring. The absence of such a genetic sex determining mechanism in dinosaurs may have led to a skewed sex ratio when global temperature dramatically changed 65,000,000 years ago, resulting in a preponderance of males, and consequentially a rapid decline in population.

  11. Sex ratio variation and sex determination in Urtica dioica

    NARCIS (Netherlands)

    Glawe, Grit Anja

    2006-01-01

    This thesis will first document on variation in progeny sex ratios among individual female plants of Urtica dioica at our field site in Meijendel (Chapter 2). Next, we show that there is also considerable sex ratio variation among male and female flowering shoots in 26 natural populations studied

  12. Molecular cytogenetic analysis of monoecious hemp (Cannabis sativa L.) cultivars reveals its karyotype variations and sex chromosomes constitution.

    Science.gov (United States)

    Razumova, Olga V; Alexandrov, Oleg S; Divashuk, Mikhail G; Sukhorada, Tatiana I; Karlov, Gennady I

    2016-05-01

    Hemp (Cannabis sativa L., 2n = 20) is a dioecious plant. Sex expression is controlled by an X-to-autosome balance system consisting of the heteromorphic sex chromosomes XY for males and XX for females. Genetically monoecious hemp offers several agronomic advantages compared to the dioecious cultivars that are widely used in hemp cultivation. The male or female origin of monoecious maternal plants is unknown. Additionally, the sex chromosome composition of monoecious hemp forms remains unknown. In this study, we examine the sex chromosome makeup in monoecious hemp using a cytogenetic approach. Eight monoecious and two dioecious cultivars were used. The DNA of 210 monoecious plants was used for PCR analysis with the male-associated markers MADC2 and SCAR323. All monoecious plants showed female amplification patterns. Fluorescence in situ hybridization (FISH) with the subtelomeric CS-1 probe to chromosomes plates and karyotyping revealed a lack of Y chromosome and presence of XX sex chromosomes in monoecious cultivars with the chromosome number 2n = 20. There was a high level of intra- and intercultivar karyotype variation detected. The results of this study can be used for further analysis of the genetic basis of sex expression in plants.

  13. The probability to initiate X chromosome inactivation is determined by the X to autosomal ratio and X chromosome specific allelic properties.

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    Kim Monkhorst

    Full Text Available In female mammalian cells, random X chromosome inactivation (XCI equalizes the dosage of X-encoded gene products to that in male cells. XCI is a stochastic process, in which each X chromosome has a probability to be inactivated. To obtain more insight in the factors setting up this probability, we studied the role of the X to autosome (X ratio A ratio in initiation of XCI, and have used the experimental data in a computer simulation model to study the cellular population dynamics of XCI.To obtain more insight in the role of the XratioA ratio in initiation of XCI, we generated triploid mouse ES cells by fusion of haploid round spermatids with diploid female and male ES cells. These fusion experiments resulted in only XXY triploid ES cells. XYY and XXX ES lines were absent, suggesting cell death related either to insufficient X-chromosomal gene dosage (XYY or to inheritance of an epigenetically modified X chromosome (XXX. Analysis of active (Xa and inactive (Xi X chromosomes in the obtained triploid XXY lines indicated that the initiation frequency of XCI is low, resulting in a mixed population of XaXiY and XaXaY cells, in which the XaXiY cells have a small proliferative advantage. This result, and findings on XCI in diploid and tetraploid ES cell lines with different X ratio A ratios, provides evidence that the X ratio A ratio determines the probability for a given X chromosome to be inactivated. Furthermore, we found that the kinetics of the XCI process can be simulated using a probability for an X chromosome to be inactivated that is proportional to the X ratio A ratio. These simulation studies re-emphasize our hypothesis that the probability is a function of the concentration of an X-encoded activator of XCI, and of X chromosome specific allelic properties determining the threshold for this activator.The present findings reveal that the probability for an X chromosome to be inactivated is proportional to the X ratio A ratio. This finding

  14. Cloning an expressed gene shared by the human sex chromosomes

    International Nuclear Information System (INIS)

    Darling, S.M.; Banting, G.S.; Pym, B.; Wolfe, J.; Goodfellow, P.N.

    1986-01-01

    The existence of genes shared by mammalian sex chromosomes has been predicted on both evolutionary and functional grounds. However, the only experimental evidence for such genes in humans is the cell-surface antigen encoded by loci on the X and Y chromosomes (MIC2X and MIC2Y, respectively), which is recognized by the monoclonal antibody 12E7. Using the bacteriophage λgt11 expression system in Escherichia coli and immunoscreening techniques, the authors have isolated a cDNA clone whose primary product is recognized by 12E7. Southern blot analysis using somatic cell hybrids containing only the human X or Y chromosomes shows that the sequences reacting with the cDNA clone are localized to the sex chromosomes. In addition, the clone hybridizes to DNAs isolated from mouse cells that have been transfected with human DNA and selected for 12E7 expression on the fluorescence-activated cell sorter. The authors conclude that the cDNA clone encodes the 12E7 antigen, which is the primary product of the MIC2 loci. The clone was used to explore sequence homology between MIC2X and MIC2Y; these loci are closely related, if not identical

  15. Y Chromosome DNA in Women's Vaginal Samples as a Biomarker of Recent Vaginal Sex and Condom Use With Male Partners in the HPV Infection and Transmission Among Couples Through Heterosexual Activity Cohort Study.

    Science.gov (United States)

    Malagón, Talía; Burchell, Ann; El-Zein, Mariam; Guénoun, Julie; Tellier, Pierre-Paul; Coutlée, François; Franco, Eduardo L

    2018-01-01

    Y chromosome DNA from male epithelial and sperm cells was detected in vaginal samples after unprotected sex in experimental studies. We assessed the strength of this association in an observational setting to examine the utility of Y chromosome DNA as a biomarker of recent sexual behaviors in epidemiological studies. The HPV (human papillomavirus) Infection and Transmission Among Couples Through Heterosexual Activity cohort study enrolled 502 women attending a university or college in Montréal, Canada, and their male partners from 2005 to 2010. Participants completed self-administered questionnaires. We used real-time polymerase chain reaction to test women's baseline vaginal samples for Y chromosome DNA and assessed which sexual behaviors were independent predictors of Y chromosome DNA positivity and quantity with logistic and negative binomial regression. Y chromosome DNA positivity decreased from 77% in women in partnerships reporting vaginal sex 0 to 1 day ago to 13% in women in partnerships reporting last vaginal sex of 15 or more days ago (adjusted odds ratio, 0.09; 95% confidence interval, 0.02-0.36). The mean proportion of exfoliated vaginal sample cells with Y chromosome DNA was much lower for women who reported always using condoms (0.01%) than for women who reported never using condoms (2.07%) (adjusted ratio, 26.8; 95% confidence interval, 8.9-80.5). No association was found with reported oral/digital sex frequency or concurrency of partnerships. Y chromosome DNA quantity is strongly associated with days since last vaginal sex and lack of condom use in observational settings. Y chromosome DNA quantity may prove useful as a correlate of recent vaginal sex in observational studies lacking data on sexual behavior, such as surveillance studies of human papillomavirus infection prevalence.

  16. The fate of W chromosomes in hybrids between wild silkmoths, Samia cynthia ssp.: no role in sex determination and reproduction.

    Science.gov (United States)

    Yoshido, A; Marec, F; Sahara, K

    2016-05-01

    Moths and butterflies (Lepidoptera) have sex chromosome systems with female heterogamety (WZ/ZZ or derived variants). The maternally inherited W chromosome is known to determine female sex in the silkworm, Bombyx mori. However, little is known about the role of W chromosome in other lepidopteran species. Here we describe two forms of the W chromosome, W and neo-W, that are transmitted to both sexes in offspring of hybrids from reciprocal crosses between subspecies of wild silkmoths, Samia cynthia. We performed crosses between S. c. pryeri (2n=28, WZ/ZZ) and S. c. walkeri (2n=26, neo-Wneo-Z/neo-Zneo-Z) and examined fitness and sex chromosome constitution in their hybrids. The F1 hybrids of both reciprocal crosses had reduced fertility. Fluorescence in situ hybridization revealed not only the expected sex chromosome constitutions in the backcross and F2 hybrids of both sexes but also females without the W (or neo-W) chromosome and males carrying the W (or neo-W) chromosome. Furthermore, crosses between the F2 hybrids revealed no association between the presence or absence of W (or neo-W) chromosome and variations in the hatchability of their eggs. Our results clearly suggest that the W (or neo-W) chromosome of S. cynthia ssp. plays no role in sex determination and reproduction, and thus does not contribute to the formation of reproductive barriers between different subspecies.

  17. Determination of Sperm Sex Ratio in Bovine Semen Using Multiplex Real-time Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    Trisadee Khamlor

    2014-10-01

    Full Text Available Gender selection is important in livestock industries; for example, female calves are required in the dairy industry. Sex-sorted semen is commonly used for the production of calves of the desired gender. However, assessment of the sex ratio of the sorted semen is tedious and expensive. In this study, a rapid, cost effective and reliable method for determining the sex ratio was developed using a multiplex real-time polymerase chain reaction (PCR assay. In this assay, the X and Y chromosome-specific markers, i.e., bovine proteolipid protein (PLP gene and sex-determining region Y (SRY were simultaneously quantified in a single tube. The multiplex real-time PCR assay was shown to have high amplification efficiencies (97% to 99% comparable to the separated-tube simplex real-time PCR assay. The results obtained from both assays were not significantly different (p>0.05. The multiplex assay was validated using reference DNA of known X ratio (10%, 50%, and 90% as templates. The measured %X in semen samples were the same within 95% confidence intervals as the expected values, i.e., >90% in X-sorted semen, <10% in Y-sorted semen and close to 50% in the unsorted semen. The multiplex real-time PCR assay as shown in this study can thus be used to assess purity of sex-sorted semen.

  18. Curious Sex Ratios and Cytoplasmic Genes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 6. Curious Sex Ratios and Cytoplasmic Genes Microbes Can Distort the Sex Ratio of Populations. Stephen J Freeland Laurence D Hurst. General Article Volume 2 Issue 6 June 1997 pp 68-78 ...

  19. Comparative genetic mapping in Fragaria virginiana reveals autosomal origin of sex chromosome

    Science.gov (United States)

    Although most flowering plants are hermaphrodite, separate sexes (dioecy) have evolved repeatedly. The evolution of sex chromosomes from autosomes can often, but not always, accompany this transition. Thus, many have argued that plant genera that contain both hermaphroditic and dioecious members pro...

  20. Sex allocation and secondary sex ratio in Cuban boa ( Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters

    Science.gov (United States)

    Frynta, Daniel; Vejvodová, Tereza; Šimková, Olga

    2016-06-01

    Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (˜200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes.

  1. Human sperm sex chromosome disomy and sperm DNA damage assessed by the neutral comet assay.

    Science.gov (United States)

    McAuliffe, M E; Williams, P L; Korrick, S A; Dadd, R; Marchetti, F; Martenies, S E; Perry, M J

    2014-10-10

    Is there an association between human sperm sex chromosome disomy and sperm DNA damage? An increase in human sperm XY disomy was associated with higher comet extent; however, there was no other consistent association of sex chromosome disomies with DNA damage. There is limited published research on the association between sex chromosome disomy and sperm DNA damage and the findings are not consistent across studies. We conducted a cross-sectional study of 190 men (25% ever smoker, 75% never smoker) from subfertile couples presenting at the Massachusetts General Hospital Fertility Clinic from January 2000 to May 2003. Multiprobe fluorescence in situ hybridization for chromosomes X, Y and 18 was used to determine XX, YY, XY and total sex chromosome disomy in sperm nuclei using an automated scoring method. The neutral comet assay was used to measure sperm DNA damage, as reflected by comet extent, percentage DNA in the comet tail, and tail distributed moment. Univariate and multiple linear regression models were constructed with sex chromosome disomy (separate models for each of the four disomic conditions) as the independent variable, and DNA damage parameters (separate models for each measure of DNA damage) as the dependent variable. Men with current or past smoking history had significantly greater comet extent (µm: regression coefficients with 95% CI) [XX18: 15.17 (1.98, 28.36); YY18: 14.68 (1.50, 27.86); XY18: 15.41 (2.37, 28.45); Total Sex Chromosome Disomy: 15.23 (2.09, 28.38)], and tail distributed moment [XX18: 3.01 (0.30, 5.72); YY18: 2.95 (0.24, 5.67); XY18: 3.04 (0.36, 5.72); Total Sex Chromosome Disomy: 3.10 (0.31, 5.71)] than men who had never smoked. In regression models adjusted for age and smoking, there was a positive association between XY disomy and comet extent. For an increase in XY disomy from 0.56 to 1.47% (representing the 25th to 75th percentile), there was a mean increase of 5.08 µm in comet extent. No other statistically significant

  2. XY sex chromosome complement, compared with XX, in the CNS confers greater neurodegeneration during experimental autoimmune encephalomyelitis.

    Science.gov (United States)

    Du, Sienmi; Itoh, Noriko; Askarinam, Sahar; Hill, Haley; Arnold, Arthur P; Voskuhl, Rhonda R

    2014-02-18

    Women are more susceptible to multiple sclerosis (MS) and have more robust immune responses than men. However, men with MS tend to demonstrate a more progressive disease course than women, suggesting a disconnect between the severity of an immune attack and the CNS response to a given immune attack. We have previously shown in an MS model, experimental autoimmune encephalomyelitis, that autoantigen-sensitized XX lymph node cells, compared with XY, are more encephalitogenic. These studies demonstrated an effect of sex chromosomes in the induction of immune responses, but did not address a potential role of sex chromosomes in the CNS response to immune-mediated injury. Here, we examined this possibility using XX versus XY bone marrow chimeras reconstituted with a common immune system of one sex chromosomal type. We found that experimental autoimmune encephalomyelitis mice with an XY sex chromosome complement in the CNS, compared with XX, demonstrated greater clinical disease severity with more neuropathology in the spinal cord, cerebellum, and cerebral cortex. A candidate gene on the X chromosome, toll-like receptor 7, was then examined. Toll-like receptor 7 expression in cortical neurons was higher in mice with XY compared with mice with XX CNS, consistent with the known neurodegenerative role for toll-like receptor 7 in neurons. These results suggest that sex chromosome effects on neurodegeneration in the CNS run counter to effects on immune responses, and may bear relevance to the clinical enigma of greater MS susceptibility in women but faster disability progression in men. This is a demonstration of a direct effect of sex chromosome complement on neurodegeneration in a neurological disease.

  3. Sex-chromosome heterochromatin variation in the wood mouse, Apodemus sylvaticus

    Czech Academy of Sciences Publication Activity Database

    Nová, P.; Reutter, B. A.; Rábová, Marie; Zima, Jan

    2002-01-01

    Roč. 96, 1-4 (2002), s. 186-190 ISSN 0301-0171 R&D Projects: GA AV ČR KSK6005114 Keywords : sex-chromosome * Apodemus sylvaticus Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.114, year: 2002

  4. Gender in plants: sex chromosomes are emerging from the fog

    Czech Academy of Sciences Publication Activity Database

    Vyskot, Boris; Hobza, Roman

    2004-01-01

    Roč. 20, č. 9 (2004), s. 432-438 ISSN 0168-9525 R&D Projects: GA AV ČR(CZ) KSK5052113 Keywords : sex chromosomes * dioecious papaya * evolution Subject RIV: BO - Biophysics Impact factor: 14.643, year: 2004

  5. Molecular analysis of sex chromosome-linked mutants in the ...

    Indian Academy of Sciences (India)

    2010-09-06

    Sep 6, 2010 ... 1Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, ... In Bombyx mori, the W chromosome determines the female sex. .... located on an autosome, and there is no difference in the ex- ..... tral nervous system or in a brain-controlled body wall muscle.

  6. Sex chromosome abnormalities and sterility in river buffalo.

    Science.gov (United States)

    Di Meo, G P; Perucatti, A; Di Palo, R; Iannuzzi, A; Ciotola, F; Peretti, V; Neglia, G; Campanile, G; Zicarelli, L; Iannuzzi, L

    2008-01-01

    Thirteen male river buffaloes, 119 females with reproductive problems (which had reached reproductive age but had failed to become pregnant in the presence of bulls) and two male co-twins underwent both clinical and cytogenetic investigation. Clinical analyses performed by veterinary practitioners revealed normal body conformation and external genitalia for most females. However, some subjects showed some slight male traits such as large base horn circumference, prominent withers and tight pelvis. Rectal palpation revealed damage to internal sex adducts varying between atrophy of Mullerian ducts to complete lack of internal sex adducts (with closed vagina). All bulls had normal karyotypes at high resolution banding, while 25 animals (23 females and 2 male co-twins) (20.7%) with reproductive problems were found to carry the following sex chromosome abnormalities: X monosomy (2 females); X trisomy (1 female); sex reversal syndrome (2 females); and free-martinism (18 females and 2 males). All female carriers were sterile. Copyright 2008 S. Karger AG, Basel.

  7. Sex determination in Madagascar geckos of the genus Paroedura (Squamata: Gekkonidae): are differentiated sex chromosomes indeed so evolutionary stable?

    Czech Academy of Sciences Publication Activity Database

    Koubová, M.; Johnson Pokorná, Martina; Rovatsos, M.; Farkačová, K.; Altmanová, M.; Kratochvíl, L.

    2014-01-01

    Roč. 22, č. 4 (2014), s. 441-452 ISSN 0967-3849 R&D Projects: GA ČR GAP506/10/0718 Institutional support: RVO:67985904 Keywords : sex chromosomes * heterochromatin * reptiles * sex determination * FISH * ITSs Subject RIV: EG - Zoology Impact factor: 2.478, year: 2014

  8. Sex-chromosome differentiation parallels postglacial range expansion in European tree frogs (Hyla arborea).

    Science.gov (United States)

    Dufresnes, Christophe; Bertholet, Youna; Wassef, Jérôme; Ghali, Karim; Savary, Romain; Pasteur, Baptiste; Brelsford, Alan; Rozenblut-Kościsty, Beata; Ogielska, Maria; Stöck, Matthias; Perrin, Nicolas

    2014-12-01

    Occasional XY recombination is a proposed explanation for the sex-chromosome homomorphy in European tree frogs. Numerous laboratory crosses, however, failed to detect any event of male recombination, and a detailed survey of NW-European Hyla arborea populations identified male-specific alleles at sex-linked loci, pointing to the absence of XY recombination in their recent history. Here, we address this paradox in a phylogeographic framework by genotyping sex-linked microsatellite markers in populations and sibships from the entire species range. Contrasting with postglacial populations of NW Europe, which display complete absence of XY recombination and strong sex-chromosome differentiation, refugial populations of the southern Balkans and Adriatic coast show limited XY recombination and large overlaps in allele frequencies. Geographically and historically intermediate populations of the Pannonian Basin show intermediate patterns of XY differentiation. Even in populations where X and Y occasionally recombine, the genetic diversity of Y haplotypes is reduced below the levels expected from the fourfold drop in copy numbers. This study is the first in which X and Y haplotypes could be phased over the distribution range in a species with homomorphic sex chromosomes; it shows that XY-recombination patterns may differ strikingly between conspecific populations, and that recombination arrest may evolve rapidly (<5000 generations). © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  9. Local offspring density and sex ratio affect sex allocation in the great tit

    NARCIS (Netherlands)

    Michler, Stephanie P. M.; Nicolaus, Marion; van der Velde, Marco; Radersma, Reinder; Ubels, Richard; Both, Christiaan; Komdeur, Jan; Tinbergen, Joost M.

    2013-01-01

    The expected fitness gain for offspring of a given sex may depend on local population sex ratio and density. Knowing the influence of such social factors on brood sex ratios may contribute considerably to the understanding of sex allocation in higher vertebrates. For 3 consecutive years, we

  10. Extraordinary sex ratios: cultural effects on ecological consequences.

    Directory of Open Access Journals (Sweden)

    Ferenc Molnár

    Full Text Available We model sex-structured population dynamics to analyze pairwise competition between groups differing both genetically and culturally. A sex-ratio allele is expressed in the heterogametic sex only, so that assumptions of Fisher's analysis do not apply. Sex-ratio evolution drives cultural evolution of a group-associated trait governing mortality in the homogametic sex. The two-sex dynamics under resource limitation induces a strong Allee effect that depends on both sex ratio and cultural trait values. We describe the resulting threshold, separating extinction from positive growth, as a function of female and male densities. When initial conditions avoid extinction due to the Allee effect, different sex ratios cannot coexist; in our model, greater female allocation always invades and excludes a lesser allocation. But the culturally transmitted trait interacts with the sex ratio to determine the ecological consequences of successful invasion. The invading female allocation may permit population persistence at self-regulated equilibrium. For this case, the resident culture may be excluded, or may coexist with the invader culture. That is, a single sex-ratio allele in females and a cultural dimorphism in male mortality can persist; a low-mortality resident trait is maintained by father-to-son cultural transmission. Otherwise, the successfully invading female allocation excludes the resident allele and culture and then drives the population to extinction via a shortage of males. Finally, we show that the results obtained under homogeneous mixing hold, with caveats, in a spatially explicit model with local mating and diffusive dispersal in both sexes.

  11. Sexual dimorphism in mammalian autosomal gene regulation is determined not only by Sry but by sex chromosome complement as well.

    Science.gov (United States)

    Wijchers, Patrick J; Yandim, Cihangir; Panousopoulou, Eleni; Ahmad, Mushfika; Harker, Nicky; Saveliev, Alexander; Burgoyne, Paul S; Festenstein, Richard

    2010-09-14

    Differences between males and females are normally attributed to developmental and hormonal differences between the sexes. Here, we demonstrate differences between males and females in gene silencing using a heterochromatin-sensitive reporter gene. Using "sex-reversal" mouse models with varying sex chromosome complements, we found that this differential gene silencing was determined by X chromosome complement, rather than sex. Genome-wide transcription profiling showed that the expression of hundreds of autosomal genes was also sensitive to sex chromosome complement. These genome-wide analyses also uncovered a role for Sry in modulating autosomal gene expression in a sex chromosome complement-specific manner. The identification of this additional layer in the establishment of sexual dimorphisms has implications for understanding sexual dimorphisms in physiology and disease. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Complex evolutionary trajectories of sex chromosomes across bird taxa

    DEFF Research Database (Denmark)

    Zhou, Qi; Zhang, Jilin; Bachtrog, Doris

    2014-01-01

    Sex-specific chromosomes, like the W of most female birds and the Y of male mammals, usually have lost most genes owing to a lack of recombination.We analyze newly available genomes of 17 bird species representing the avian phylogenetic range, and find that more than half of them do not have...

  13. Skewed sex ratios in India: "physician, heal thyself".

    Science.gov (United States)

    Patel, Archana B; Badhoniya, Neetu; Mamtani, Manju; Kulkarni, Hemant

    2013-06-01

    Sex selection, a gender discrimination of the worst kind, is highly prevalent across all strata of Indian society. Physicians have a crucial role in this practice and implementation of the Indian Government's Pre-Natal Diagnostic Techniques Act in 1996 to prevent the misuse of ultrasound techniques for the purpose of prenatal sex determination. Little is known about family preferences, let alone preferences among families of physicians. We investigated the sex ratios in 946 nuclear families with 1,624 children, for which either one or both parents were physicians. The overall child sex ratio was more skewed than the national average of 914. The conditional sex ratios decreased with increasing number of previous female births, and a previous birth of a daughter in the family was associated with a 38 % reduced likelihood of a subsequent female birth. The heavily skewed sex ratios in the families of physicians are indicative of a deeply rooted social malady that could pose a critical challenge in correcting the sex ratios in India.

  14. Rapid molecular sexing of three-spined sticklebacks, Gasterosteus aculeatus L., based on large Y-chromosomal insertions.

    Science.gov (United States)

    Bakker, Theo C M; Giger, Thomas; Frommen, Joachim G; Largiadèr, Carlo R

    2017-08-01

    There is a need for rapid and reliable molecular sexing of three-spined sticklebacks, Gasterosteus aculeatus, the supermodel species for evolutionary biology. A DNA region at the 5' end of the sex-linked microsatellite Gac4202 was sequenced for the X chromosome of six females and the Y chromosome of five males from three populations. The Y chromosome contained two large insertions, which did not recombine with the phenotype of sex in a cross of 322 individuals. Genetic variation (SNPs and indels) within the insertions was smaller than on flanking DNA sequences. Three molecular PCR-based sex tests were developed, in which the first, the second or both insertions were covered. In five European populations (from DE, CH, NL, GB) of three-spined sticklebacks, tests with both insertions combined showed two clearly separated bands on agarose minigels in males and one band in females. The tests with the separate insertions gave similar results. Thus, the new molecular sexing method gave rapid and reliable results for sexing three-spined sticklebacks and is an improvement and/or alternative to existing methods.

  15. To Break or Not To Break: Sex Chromosome Hemizygosity During Meiosis in Caenorhabditis.

    Science.gov (United States)

    Van, Mike V; Larson, Braden J; Engebrecht, JoAnne

    2016-11-01

    Meiotic recombination establishes connections between homologous chromosomes to promote segregation. Hemizygous regions of sex chromosomes have no homologous chromosome to recombine with, yet must be transmitted through meiosis. An extreme case of hemizygosity exists in the genus Caenorhabditis, where males have a single X chromosome that completely lacks a homologous partner. To determine whether similar strategies have evolved to accommodate hemizygosity of the X during male meiosis in Caenorhabditis with distinct modes of sexual reproduction, we examined induction and processing of meiotic double strand breaks (DSBs) in androdioecious (hermaphrodite/male) Caenorhabditis elegans and C. briggsae, and gonochoristic (female/male) C. remanei and C. brenneri Analysis of the recombinase RAD-51 suggests more meiotic DSBs are induced in gonochoristic vs. androdioecious species. However, in late prophase in all species, chromosome pairs are restructured into bivalents around a single axis, suggesting that the holocentric nature of Caenorhabditis chromosomes dictates a single crossover per bivalent regardless of the number of DSBs induced. Interestingly, RAD-51 foci were readily observed on the X chromosome of androdioecious male germ cells, while very few were detected in gonochoristic male germ cells. As in C. elegans, the X chromosome in C. briggsae male germ cells undergoes transient pseudosynapsis and flexibility in DSB repair pathway choice. In contrast, in C. remanei and C. brenneri male germ cells, the X chromosome does not undergo pseudosynapsis and appears refractory to SPO-11-induced breaks. Together our results suggest that distinct strategies have evolved to accommodate sex chromosome hemizygosity during meiosis in closely related Caenorhabditis species. Copyright © 2016 by the Genetics Society of America.

  16. Fetal sex determination in the first trimester of pregnancy using a Y chromosome-specific DNA probe

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Y.; Huang, S.; Chen, M.; Huang, Y.; Zhang, M.; Dong, J.; Ku, A.; Xu, S.

    1987-05-01

    Prenatal determination of fetal sex is important for the prevention of X-linked disorders such as hemophilia, Lesch-Nyhan syndrome and Duchenne muscular dystrophy. The complex procedures of prenatal diagnosis for X-linked disorders are unnecessary if the fetus is female, because usually no clinical symptoms ever appear in female. pY 3.4 probe used in this work for sex determination is a 3.4 kilobase human repeat sequence. The probe is specific for the Y chromosome of males and can be used for sex determination. The other prove pBLUR used in this paper as control is a widely dispersed, highly repeated human Alu family DNA sequence, represented equally in male and female DNA. On the basis of the relative densities of the autoradiographic spots produced by hybridization of fetal DNA with pY3.4 and pBLUR, the sex of fetus can be clearly identified. Further the authors can determine the radioactive intensity (cpm) of the hybridized DNA spots and the ratio of hybridization with Y3.4 to pBLUR (Y3.4/pBLUR x 10). Results show that the hybridization ratio of DNA from chorionic villi of male (1.03 +/- 0.24) is significantly higher than that of female (0.16 +/- 0.09). Therefore, sex determination of the fetus can be made, based on the ratio of pY3.4/pBLUR x 10. If necessary they can also use Southern hybridization with pY 3.4 probe of DNA isolated from chorionic villi to confirm the result of dot hybridization.

  17. Positive selection of deleterious alleles through interaction with a sex-ratio suppressor gene in African Buffalo: a plausible new mechanism for a high frequency anomaly.

    Directory of Open Access Journals (Sweden)

    Pim van Hooft

    Full Text Available Although generally rare, deleterious alleles can become common through genetic drift, hitchhiking or reductions in selective constraints. Here we present a possible new mechanism that explains the attainment of high frequencies of deleterious alleles in the African buffalo (Syncerus caffer population of Kruger National Park, through positive selection of these alleles that is ultimately driven by a sex-ratio suppressor. We have previously shown that one in four Kruger buffalo has a Y-chromosome profile that, despite being associated with low body condition, appears to impart a relative reproductive advantage, and which is stably maintained through a sex-ratio suppressor. Apparently, this sex-ratio suppressor prevents fertility reduction that generally accompanies sex-ratio distortion. We hypothesize that this body-condition-associated reproductive advantage increases the fitness of alleles that negatively affect male body condition, causing genome-wide positive selection of these alleles. To investigate this we genotyped 459 buffalo using 17 autosomal microsatellites. By correlating heterozygosity with body condition (heterozygosity-fitness correlations, we found that most microsatellites were associated with one of two gene types: one with elevated frequencies of deleterious alleles that have a negative effect on body condition, irrespective of sex; the other with elevated frequencies of sexually antagonistic alleles that are negative for male body condition but positive for female body condition. Positive selection and a direct association with a Y-chromosomal sex-ratio suppressor are indicated, respectively, by allele clines and by relatively high numbers of homozygous deleterious alleles among sex-ratio suppressor carriers. This study, which employs novel statistical techniques to analyse heterozygosity-fitness correlations, is the first to demonstrate the abundance of sexually-antagonistic genes in a natural mammal population. It also has

  18. Do Workplace Sex Ratios Affect Partnership Formation and Dissolution?

    DEFF Research Database (Denmark)

    Svarer, Michael

    In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios are not ......In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios...

  19. Differentiation of Sex Chromosomes and Karyotype Characterisation in the Dragonsnake Xenodermus javanicus (Squamata: Xenodermatidae)

    Czech Academy of Sciences Publication Activity Database

    Rovatsos, M.; Johnson Pokorná, Martina; Kratochvíl, L.

    2015-01-01

    Roč. 147, č. 1 (2015), s. 48-54 ISSN 1424-8581 Institutional support: RVO:67985904 Keywords : interstitial telomeric repeats * sex chromosomes * sex determination Subject RIV: EG - Zoology Impact factor: 1.638, year: 2015

  20. Sex ratios of Mountain Plovers from egg production to fledging

    Directory of Open Access Journals (Sweden)

    Margaret M. Riordan

    2015-12-01

    Full Text Available Skewed sex ratios can have negative implications for population growth if they do not match a species' life history. A skewed tertiary sex ratio has been detected in a population of Mountain Plover (Charadrius montanus, a grassland shorebird experiencing population declines. To study the cause of the observed male skew, we examined three early life stages between egg and fledgling in eastern Colorado from 2010 to 2012. This allows us to distinguish between egg production and chick survival as an explanation for the observed skew. We examined the primary sex ratio in eggs produced and the secondary sex ratio in hatched chicks to see if the sex ratio bias occurs before hatching. We also determined the sex ratio at fledging to reveal sex-specific mortality of nestlings. The primary sex ratio was 1.01 (± 0.01 males per female. The secondary sex ratio consisted of 1.10 (± 0.02 males per female. The probability of a chick surviving to fledging differed between males (0.55 ± 0.13 and females (0.47 ± 0.15, but the precision of these survival estimates was low. Sex ratios in early life stages of the Mountain Plover do not explain the skewed sex ratio observed in adults in this breeding population.

  1. A major locus on mouse chromosome 18 controls XX sex reversal in Odd Sex (Ods) mice.

    Science.gov (United States)

    Qin, Yangjun; Poirier, Christophe; Truong, Cavatina; Schumacher, Armin; Agoulnik, Alexander I; Bishop, Colin E

    2003-03-01

    We have previously reported a dominant mouse mutant, Odd sex (Ods), in which XX Ods/+ mice on the FVB/N background show complete sex reversal, associated with expression of Sox9 in the fetal gonads. Remarkably, when crossed to the A/J strain approximately 95% of the (AXFVB) F(1) XX Ods/+ mice developed as fully fertile, phenotypic females, the remainder developing as males or hermaphrodites. Using a (AXFVB) F(2) population, we conducted a genome-wide linkage scan to identify the number and chromosomal location of potential Ods modifier genes. A single major locus termed Odsm1 was mapped to chromosome 18, tightly linked to D18Mit189 and D18Mit210. Segregation at this locus could account for the presence of sex reversal in 100% of XX Ods/+ mice which develop as males, for the absence of sex reversal in approximately 92% of XX Ods/+ mice which develop as females, and for the mixed sexual phenotype in approximately 72% of XX Ods/+ mice that develop with ambiguous genitalia. We propose that homozygosity for the FVB-derived allele strongly favors Ods sex reversal, whereas homozygosity for the A/J-derived allele inhibits it. In mice heterozygous at Odsm1, the phenotypic outcome, male, female or hermaphrodite, is determined by a complex interaction of several minor modifying loci. The close proximity of Smad2, Smad7 and Smad4 to D18Mit189/210 provides a potential mechanism through which Odsm1 might act.

  2. Sex, rebellion and decadence: the scandalous evolutionary history of the human Y chromosome.

    Science.gov (United States)

    Navarro-Costa, Paulo

    2012-12-01

    It can be argued that the Y chromosome brings some of the spirit of rock&roll to our genome. Equal parts degenerate and sex-driven, the Y has boldly rebelled against sexual recombination, one of the sacred pillars of evolution. In evolutionary terms this chromosome also seems to have adopted another of rock&roll's mottos: living fast. Yet, it appears to have refused to die young. In this manuscript the Y chromosome will be analyzed from the intersection between structural, evolutionary and functional biology. Such integrative approach will present the Y as a highly specialized product of a series of remarkable evolutionary processes. These led to the establishment of a sex-specific genomic niche that is maintained by a complex balance between selective pressure and the genetic diversity introduced by intrachromosomal recombination. Central to this equilibrium is the "polish or perish" dilemma faced by the male-specific Y genes: either they are polished by the acquisition of male-related functions or they perish via the accumulation of inactivating mutations. Thus, understanding to what extent the idiosyncrasies of Y recombination may impact this chromosome's role in sex determination and male germline functions should be regarded as essential for added clinical insight into several male infertility phenotypes. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Density-dependent sex ratio and sex-specific preference for host traits in parasitic bat flies.

    Science.gov (United States)

    Szentiványi, Tamara; Vincze, Orsolya; Estók, Péter

    2017-08-29

    Deviation of sex ratios from unity in wild animal populations has recently been demonstrated to be far more prevalent than previously thought. Ectoparasites are prominent examples of this bias, given that their sex ratios vary from strongly female- to strongly male-biased both among hosts and at the metapopulation level. To date our knowledge is very limited on how and why these biased sex ratios develop. It was suggested that sex ratio and sex-specific aggregation of ectoparasites might be shaped by the ecology, behaviour and physiology of both hosts and their parasites. Here we investigate a highly specialised, hematophagous bat fly species with strong potential to move between hosts, arguably limited inbreeding effects, off-host developmental stages and extended parental care. We collected a total of 796 Nycteribia kolenatii bat flies from 147 individual bats using fumigation and subsequently determined their sex. We report a balanced sex ratio at the metapopulation level and a highly variable sex ratio among infrapopulations ranging from 100% male to 100% female. We show that infrapopulation sex ratio is not random and is highly correlated with infrapopulation size. Sex ratio is highly male biased in small and highly female biased in large infrapopulations. We show that this pattern is most probably the result of sex-specific preference in bat flies for host traits, most likely combined with a higher mobility of males. We demonstrate that female bat flies exert a strong preference for high host body condition and female hosts, while the distribution of males is more even. Our results suggest that locally biased sex ratios can develop due to sex-specific habitat preference of parasites. Moreover, it is apparent that the sex of both hosts and parasites need to be accounted for when a better understanding of host-parasite systems is targeted.

  4. Integrated gene mapping and synteny studies give insights into the evolution of a sex proto-chromosome in Solea senegalensis.

    Science.gov (United States)

    Portela-Bens, Silvia; Merlo, Manuel Alejandro; Rodríguez, María Esther; Cross, Ismael; Manchado, Manuel; Kosyakova, Nadezda; Liehr, Thomas; Rebordinos, Laureana

    2017-03-01

    The evolution of genes related to sex and reproduction in fish shows high plasticity and, to date, the sex determination system has only been identified in a few species. Solea senegalensis has 42 chromosomes and an XX/XY chromosome system for sex determination, while related species show the ZZ/ZW system. Next-generation sequencing (NGS), multi-color fluorescence in situ hybridization (mFISH) techniques, and bioinformatics analysis have been carried out, with the objective of revealing new information about sex determination and reproduction in S. senegalensis. To that end, several bacterial artificial chromosome (BAC) clones that contain candidate genes involved in such processes (dmrt1, dmrt2, dmrt3, dmrt4, sox3, sox6, sox8, sox9, lh, cyp19a1a, amh, vasa, aqp3, and nanos3) were analyzed and compared with the same region in other related species. Synteny studies showed that the co-localization of dmrt1-dmrt2-drmt3 in the largest metacentric chromosome of S. senegalensis is coincident with that found in the Z chromosome of Cynoglossus semilaevis, which would potentially make this a sex proto-chromosome. Phylogenetic studies show the close proximity of S. senegalensis to Oryzias latipes, a species with an XX/XY system and a sex master gene. Comparative mapping provides evidence of the preferential association of these candidate genes in particular chromosome pairs. By using the NGS and mFISH techniques, it has been possible to obtain an integrated genetic map, which shows that 15 out of 21 chromosome pairs of S. senegalensis have at least one BAC clone. This result is important for distinguishing those chromosome pairs of S. senegalensis that are similar in shape and size. The mFISH analysis shows the following co-localizations in the same chromosomes: dmrt1-dmrt2-dmrt3, dmrt4-sox9-thrb, aqp3-sox8, cyp19a1a-fshb, igsf9b-sox3, and lysg-sox6.

  5. Heritable Variation for Sex Ratio under Environmental Sex Determination in the Common Snapping Turtle (Chelydra Serpentina)

    Science.gov (United States)

    Janzen, F. J.

    1992-01-01

    The magnitude of quantitative genetic variation for primary sex ratio was measured in families extracted from a natural population of the common snapping turtle (Chelydra serpentina), which possesses temperature-dependent sex determination (TSD). Eggs were incubated at three temperatures that produced mixed sex ratios. This experimental design provided estimates of the heritability of sex ratio in multiple environments and a test of the hypothesis that genotype X environment (G X E) interactions may be maintaining genetic variation for sex ratio in this population of C. serpentina. Substantial quantitative genetic variation for primary sex ratio was detected in all experimental treatments. These results in conjunction with the occurrence of TSD in this species provide support for three critical assumptions of Fisher's theory for the microevolution of sex ratio. There were statistically significant effects of family and incubation temperature on sex ratio, but no significant interaction was observed. Estimates of the genetic correlations of sex ratio across environments were highly positive and essentially indistinguishable from +1. These latter two findings suggest that G X E interaction is not the mechanism maintaining genetic variation for sex ratio in this system. Finally, although substantial heritable variation exists for primary sex ratio of C. serpentina under constant temperatures, estimates of the effective heritability of primary sex ratio in nature are approximately an order of magnitude smaller. Small effective heritability and a long generation time in C. serpentina imply that evolution of sex ratios would be slow even in response to strong selection by, among other potential agents, any rapid and/or substantial shifts in local temperatures, including those produced by changes in the global climate. PMID:1592234

  6. 3. Pattern of Inheritance of Autosome and Sex. Chromosome Linked ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. Teaching and Learning Genetics with Drosophila – Pattern of Inheritance of Autosome and Sex Chro-mosome Linked Genes/Characters. H A Ranganath M T Tanuja. Classroom Volume 4 Issue 10 October 1999 pp 78-87 ...

  7. Curious Sex Ratios and Cytoplasmic Genes

    Indian Academy of Sciences (India)

    instances of curious sex ratios exemplify an important principle: the fitness ..... markable transition - the whole means of sex determination has changed. No longer ... to the cytoplasmic symbiont is self-evident; the symbionts simply increase the.

  8. Skewed sex ratios and criminal victimization in India.

    Science.gov (United States)

    South, Scott J; Trent, Katherine; Bose, Sunita

    2014-06-01

    Although substantial research has explored the causes of India's excessively masculine population sex ratio, few studies have examined the consequences of this surplus of males. We merge individual-level data from the 2004-2005 India Human Development Survey with data from the 2001 India population census to examine the association between the district-level male-to-female sex ratio at ages 15 to 39 and self-reports of victimization by theft, breaking and entering, and assault. Multilevel logistic regression analyses reveal positive and statistically significant albeit substantively modest effects of the district-level sex ratio on all three victimization risks. We also find that higher male-to-female sex ratios are associated with the perception that young unmarried women in the local community are frequently harassed. Household-level indicators of family structure, socioeconomic status, and caste, as well as areal indicators of women's empowerment and collective efficacy, also emerge as significant predictors of self-reported criminal victimization and the perceived harassment of young women. The implications of these findings for India's growing sex ratio imbalance are discussed.

  9. Skewed Sex Ratios and Criminal Victimization in India

    Science.gov (United States)

    South, Scott J.; Trent, Katherine; Bose, Sunita

    2014-01-01

    Although substantial research has explored the causes of India’s excessively masculine population sex ratio, few studies have examined the consequences of this surplus of males. We merge individual-level data from the 2004–2005 India Human Development Survey with data from the 2001 India population census to examine the association between the district-level male-to-female sex ratio at ages 15 to 39 and self-reports of victimization by theft, breaking and entering, and assault. Multilevel logistic regression analyses reveal positive and statistically significant albeit substantively modest effects of the district-level sex ratio on all three victimization risks. We also find that higher male-to-female sex ratios are associated with the perception that young unmarried women in the local community are frequently harassed. Household-level indicators of family structure, socioeconomic status, and caste, as well as areal indicators of women’s empowerment and collective efficacy, also emerge as significant predictors of self-reported criminal victimization and the perceived harassment of young women. The implications of these findings for India’s growing sex ratio imbalance are discussed. PMID:24682921

  10. Inter-Annual Variability of Fledgling Sex Ratio in King Penguins.

    Directory of Open Access Journals (Sweden)

    Célia Bordier

    Full Text Available As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (2000-2009 in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus, we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males, and on average slightly biased towards males (51.6%. Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally, suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1∶1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.

  11. Inter-Annual Variability of Fledgling Sex Ratio in King Penguins.

    Science.gov (United States)

    Bordier, Célia; Saraux, Claire; Viblanc, Vincent A; Gachot-Neveu, Hélène; Beaugey, Magali; Le Maho, Yvon; Le Bohec, Céline

    2014-01-01

    As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (2000-2009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1∶1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.

  12. Polytene chromosome analysis in relation to genetic sex separation in the Mediterranean fruit fly, Ceratitis capitata (Wied.)

    International Nuclear Information System (INIS)

    Kerremans, P.; Busch-Petersen, E.

    1990-01-01

    The development of stable genetic sexing strains in the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), is hampered by the presence of low levels of male recombination. Such recombination may be reduced by minimizing the distance between the translocation breakpoint and the translocated 'sexing' allele. Cytogenetic analysis of mitotic/meiotic and polytene chromosomes could provide information on the selection of such potentially stable genetic sexing strains. Translocation breakpoints in two genetic sexing strains in the medfly, based on a white female/brown male pupal colour dimorphism, have been determined. Preliminary results are described and the advantages and limitations of polytene chromosome analysis for the isolation of stable genetic sexing strains of the medfly are discussed. (author). 31 refs

  13. Demographic origins of skewed operational and adult sex ratios: perturbation analyses of two-sex models.

    Science.gov (United States)

    Veran, Sophie; Beissinger, Steven R

    2009-02-01

    Skewed sex ratios - operational (OSR) and Adult (ASR) - arise from sexual differences in reproductive behaviours and adult survival rates due to the cost of reproduction. However, skewed sex-ratio at birth, sex-biased dispersal and immigration, and sexual differences in juvenile mortality may also contribute. We present a framework to decompose the roles of demographic traits on sex ratios using perturbation analyses of two-sex matrix population models. Metrics of sensitivity are derived from analyses of sensitivity, elasticity, life-table response experiments and life stage simulation analyses, and applied to the stable stage distribution instead of lambda. We use these approaches to examine causes of male-biased sex ratios in two populations of green-rumped parrotlets (Forpus passerinus) in Venezuela. Female local juvenile survival contributed the most to the unbalanced OSR and ASR due to a female-biased dispersal rate, suggesting sexual differences in philopatry can influence sex ratios more strongly than the cost of reproduction.

  14. Sex ratio and Wolbachia infection in the ant Formica exsecta.

    Science.gov (United States)

    Keller, L; Liautard, C; Reuter, M; Brown, W D; Sundström, L; Chapuisat, M

    2001-08-01

    Sex allocation data in social Hymenoptera provide some of the best tests of kin selection, parent-offspring conflict and sex ratio theories. However, these studies critically depend on controlling for confounding ecological factors and on identifying all parties that potentially manipulate colony sex ratio. It has been suggested that maternally inherited parasites may influence sex allocation in social Hymenoptera. If the parasites can influence sex allocation, infected colonies are predicted to invest more resources in females than non-infected colonies, because the parasites are transmitted through females but not males. Prime candidates for such sex ratio manipulation are Wolbachia, because these cytoplasmically transmitted bacteria have been shown to affect the sex ratio of host arthropods by cytoplasmic incompatibility, parthenogenesis, male-killing and feminization. In this study, we tested whether Wolbachia infection is associated with colony sex ratio in two populations of the ant Formica exsecta that have been the subject of extensive sex ratio studies. In these populations colonies specialize in the production of one sex or the other. We found that almost all F. exsecta colonies in both populations are infected with Wolbachia. However, in neither population did we find a significant association in the predicted direction between the prevalence of Wolbachia and colony sex ratio. In particular, colonies with a higher proportion of infected workers did not produce more females. Hence, we conclude that Wolbachia does not seem to alter the sex ratio of its hosts as a means to increase transmission rate in these two populations of ants.

  15. Sex ratio selection and multi-factorial sex determination in the housefly : A dynamic model

    NARCIS (Netherlands)

    Kozielska, M.A.; Pen, I.R.; Beukeboom, L.W.; Weissing, F.J.

    Sex determining (SD) mechanisms are highly variable between different taxonomic groups and appear to change relatively quickly during evolution. Sex ratio selection could be a dominant force causing such changes. We investigate theoretically the effect of sex ratio selection on the dynamics of a

  16. Sex, sex-ratios, and the dynamics of pelagic copepod populations

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2006-01-01

    equal adult sex ratios in field populations. Winter population densities are orders of magnitude less than the critical population density required for population persistence, but populations survive winter seasons as resting eggs in the sediment. Population growth in these species is potentially high...... because they have on average a factor of 2 higher egg production rates than other pelagic copepods. Secondly, other copepods require only one mating to stay fertile, and populations of these species have strongly female-skewed adult sex-ratios in field populations. Resting eggs have not been described...

  17. Polytene chromosomes of monogenic and amphogenic Chrysomya species (Calliphoridae, Diptera): analysis of banding patterns and in situ hybridization with Drosophila sex determining gene sequences.

    Science.gov (United States)

    Puchalla, S

    1994-03-01

    Standard maps for the five banded polytene chromosomes found in trichogen cell nuclei of the monogenic blowfly Chrysomya rufifacies and the amphogenic Chrysomya pinguis are presented. The chromosomes are highly homologous in the two species; differences in banding patterns are predominantly caused by one pericentric and ten paracentric inversions. In chromosome 5 of the amphogenic Chrysomya phaonis, also analysed in this paper, an additional paracentric inversion was observed. The distribution of species specific inversions indicates that the monogenic C. rufifacies is phylogenetically older than the amphogenic species. The maternal sex realizer locus F'/f on polytene chromosome 5 of C. rufifacies is not associated with a structural heterozygosity. Chromosome pair 6 of C. rufifacies and the sex chromosome pair of C. pinguis are under-replicated in polytene nuclei; they consist of irregular chromatin granules, frequently associated with nucleolus material. Evolution of heteromorphic sex chromosomes in Chrysomya is probably correlated with heterochromatin accumulation. A search for sex determining genes in Chrysomya was initiated using sex determining sequences from Drosophila melanogaster for in situ hybridization. The polytene band 41A1 on chromosome 5 of monogenic and amphogenic Chrysomya species contains sequences homologous to the maternal sex determining gene daughterless (da). Homology to the zygotic gene Sex-lethal (Sxl) of Drosophila is detected in band 39A1 on chromosome 5 of C. rufifacies. The findings reported here are the first evidence for a possible homology between the da gene of Drosophila and the maternal sex realizer F' of C. rufifacies. An hypothesis for the evolution of the maternal effect sex determination of C. rufifacies is proposed.

  18. Getting past nature as a guide to the human sex ratio.

    Science.gov (United States)

    Murphy, Timothy F

    2013-05-01

    Sex selection of children by pre-conception and post-conception techniques remains morally controversial and even illegal in some jurisdictions. Among other things, some critics fear that sex selection will distort the sex ratio, making opposite-sex relationships more difficult to secure, while other critics worry that sex selection will tilt some nations toward military aggression. The human sex ratio varies depending on how one estimates it; there is certainly no one-to-one correspondence between males and females either at birth or across the human lifespan. Complications about who qualifies as 'male' and 'female' complicate judgments about the ratio even further. Even a judiciously estimated sex ratio does not have, however, the kind of normative status that requires society to refrain from antenatal sex selection. Some societies exhibit lopsided sex ratios as a consequence of social policies and practices, and pragmatic estimates of social needs are a better guide to what the sex ratio should be, as against looking to 'nature'. The natural sex ratio cannot be a sound moral basis for prohibiting parents from selecting the sex of their children, since it ultimately lacks any normative meaning for social choices. © 2011 Blackwell Publishing Ltd.

  19. Mother's occupation and sex ratio at birth

    Directory of Open Access Journals (Sweden)

    Amiot Volodymyr

    2010-05-01

    Full Text Available Abstract Background Many women are working outside of the home, occupying a multitude of jobs with varying degrees of responsibilities and levels of psychological stress. We investigated whether different job types in women are associated with child sex at birth, with the hypothesis that women in job types, which are categorized as "high psychological stress" jobs, would be more likely to give birth to a daughter than a son, as females are less vulnerable to unfavourable conditions during conception, pregnancy and after parturition, and are less costly to carry to term. Methods We investigated the effects of mother's age, maternal and paternal job type (and associated psychological stress levels and paternal income on sex ratio at birth. Our analyses were based on 16,384 incidences of birth from a six-year (2000 to 2005 inclusive childbirth dataset from Addenbrooke's Hospital in Cambridge, UK. We obtained a restricted data set from Addenbrooke's hospital with: maternal age, maternal and paternal occupations, and whether or not the child was first-born. Results Women in job types that were categorized as "high stress" were more likely to give birth to daughters, whereas women in job types that were categorized as "low stress" had equal sex ratios or a slight male bias in offspring. We also investigated whether maternal age, and her partner's income could be associated with reversed offspring sex ratio. We found no association between mother's age, her partner's job stress category or partner income on child sex. However, there was an important interaction between job stress category and partner income in some of the analyses. Partner income appears to attenuate the association between maternal job stress and sex ratios at moderate-income levels, and reverse it at high-income levels. Conclusions To our knowledge this is the first report on the association between women's job type stress categories and offspring sex ratio in humans, and the

  20. Empirical evidence for large X-effects in animals with undifferentiated sex chromosomes

    Czech Academy of Sciences Publication Activity Database

    Dufresnes, C.; Majtyka, T.; Baird, Stuart J. E.; Gerchen, J. F.; Borzée, A.; Savary, R.; Ogielska, M.; Perrin, N.; Stöck, M.

    2016-01-01

    Roč. 6, č. 21029 (2016), s. 21029 ISSN 2045-2322 Institutional support: RVO:68081766 Keywords : controlled study * genetic marker * hybrid zone * Hyla * introgression * sex chromosome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.259, year: 2016

  1. Tissue- and stage-dependent dosage compensation on the Neo-X chromosome in drosophila pseudoobscura

    KAUST Repository

    Nozawa, Masafumi

    2013-12-03

    Sex chromosome dosage compensation (DC) is widely accepted in various organisms. This concept is mostly supported by comparisons of gene expression between chromosomes and between sexes. However, genes on the X chromosome and autosomes are mostly not homologous, and the average gene expression level on these chromosomes may not be the same even under DC, which complicates comparisons between chromosomes. Many genes with sex-biased expression also make comparisons between sexes difficult. To overcome these issues, we investigated DC by comparing the expression of neo-X-linked genes in Drosophila pseudoobscura with those of their autosomal orthologs in other Drosophila species. The ratio of the former to the latter in males would be 1 under DC, whereas it becomes 0.5 without DC. We found that the ratio was ∼0.85 for adult whole bodies, indicating that the DC is incomplete on the neo-X chromosome in adults as a whole. The ratio (∼0.90) was also significantly less than 1 for adult bodies without gonads, whereas it was ∼1.0 for adult heads. These results indicate that DC varies among tissues. Our sliding-window analysis of the ratio also revealed that the upregulation of neo-X-linked genes in males occurred chromosome wide in all tissues analyzed, indicating global upregulation mechanisms. However, we found that gene functions also affected the levels of DC. Furthermore, most of the genes recently moved to the X were already under DC at the larval stage but not at the adult stage. These results suggest that DC in Drosophila species operates in a tissue/stage-dependent manner. © 2013 The Author 2013. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved.

  2. Incomplete sex chromosome dosage compensation in the Indian meal moth, Plodia interpunctella, based on de novo transcriptome assembly.

    Science.gov (United States)

    Harrison, Peter W; Mank, Judith E; Wedell, Nina

    2012-01-01

    Males and females experience differences in gene dose for loci in the nonrecombining region of heteromorphic sex chromosomes. If not compensated, this leads to expression imbalances, with the homogametic sex on average exhibiting greater expression due to the doubled gene dose. Many organisms with heteromorphic sex chromosomes display global dosage compensation mechanisms, which equalize gene expression levels between the sexes. However, birds and Schistosoma have been previously shown to lack chromosome-wide dosage compensation mechanisms, and the status in other female heterogametic taxa including Lepidoptera remains unresolved. To further our understanding of dosage compensation in female heterogametic taxa and to resolve its status in the lepidopterans, we assessed the Indian meal moth, Plodia interpunctella. As P. interpunctella lacks a complete reference genome, we conducted de novo transcriptome assembly combined with orthologous genomic location prediction from the related silkworm genome, Bombyx mori, to compare Z-linked and autosomal gene expression levels for each sex. We demonstrate that P. interpunctella lacks complete Z chromosome dosage compensation, female Z-linked genes having just over half the expression level of males and autosomal genes. This finding suggests that the Lepidoptera and possibly all female heterogametic taxa lack global dosage compensation, although more species will need to be sampled to confirm this assertion.

  3. Exploring the possibilities for stabilizing the sex ratio in India

    Directory of Open Access Journals (Sweden)

    Saurabh RamBihariLal Shrivastava

    2015-12-01

    Full Text Available The sex ratio is an important demographic indicator for a nation. A wide range of adverse social consequences have been observed because of a skewed sex ratio in India. If India as a nation is to achieve the Millennium Development Goal – 3 (which promotes gender equality and ensures the empowerment of women, the primary target should be involve all those involved, so that a collective and comprehensive approach can be developed to counter the public health menace of an asymmetrical sex ratio. In conclusion, the nation’s program managers should prioritize the issue of a skewed sex ratio and work towards developing a coordinated response.Key Words: Sex ratio, policy makers, India.

  4. Mode of action, origin and structure of the Paternal Sex Ratio chromosome in the parasitoid wasp Trichogramma kaykai

    NARCIS (Netherlands)

    Vugt, van J.J.F.A.

    2005-01-01

    Selfish genetic elements are defined as genetic elements that have a replication advantage relative to the rest of the genome. They are ubiquitous in nature and were extensively reported for almost all species studied so far. A special type of selfish genetic element, the sex ratio distorter, is

  5. Sex Chromosome Evolution and Genomic Divergence in the Fish Hoplias malabaricus (Characiformes, Erythrinidae)

    Czech Academy of Sciences Publication Activity Database

    Sember, Alexandr; Bertollo, L.A.C.; Ráb, Petr; Yano, C. F.; Hatanaka, T.; de Oliveira, E. A.; de Bello Cioffi, M.

    2018-01-01

    Roč. 9, č. 1 (2018), č. článku 71. ISSN 1664-8021 R&D Projects: GA MŠk EF15_003/0000460 Institutional support: RVO:67985904 Keywords : fish cytogenetics * multiple sex chromosomes * sex-determining region Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 3.789, year: 2016

  6. Patterns of Family Formation in Response to Sex Ratio Variation.

    Science.gov (United States)

    Schacht, Ryan; Kramer, Karen L

    2016-01-01

    The impact that unbalanced sex ratios have on health and societal outcomes is of mounting contemporary concern. However, it is increasingly unclear whether it is male- or female-biased sex ratios that are associated with family and social instability. From a socio-demographic perspective, male-biased sex ratios leave many men unable to find a mate, elevating competition among males, disrupting family formation and negatively affecting social stability. In contrast, from a mating-market perspective, males are expected to be less willing to marry and commit to a family when the sex ratio is female-biased and males are rare. Here we use U.S. data to evaluate predictions from these competing frameworks by testing the relationship between the adult sex ratio and measures of family formation. We find that when women are rare men are more likely to marry, be part of a family and be sexually committed to a single partner. Our results do not support claims that male-biased sex ratios lead to negative family outcomes due to a surplus of unmarried men. Rather, our results highlight the need to pay increased attention to female-biased sex ratios.

  7. Molecular cytogenetics and characterization of a ZZ/ZW sex chromosome system in Triportheus nematurus (Characiformes, Characidae).

    Science.gov (United States)

    Diniz, Débora; Moreira-Filho, Orlando; Bertollo, Luiz Antonio Carlos

    2008-05-01

    Chromosomes of Triportheus nematurus, a fish species from family Characidae, were analyzed in order to establish the conventional karyotype, location of C-band positive heterochromatin, Ag-NORs, GC- and AT-rich sites, and mapping of 18S and 5S rDNA with fluorescence in situ hybridization (FISH). The diploid number found was 2n = 52 chromosomes in both males and females. However, the females presented a pair of differentiated heteromorphic chromosomes, characterizing a ZZ/ZW sex chromosome system. The Z chromosome was metacentric and the largest one in the karyotype, bearing C-positive heterochromatin at pericentromeric and telomeric regions. The W chromosome was middle-sized submetacentric, appearing mostly heterochromatic after C-banding and presenting heterogeneous heterochromatin composed of GC- and AT-rich regions revealed by fluorochrome staining. Ag-NORs were also GC-rich and surrounded by heterochromatic regions, being located at the secondary constriction on the short arms of the second chromosome pair, in agreement with 18S rDNA sites detected with FISH. The 18S and 5S rDNA were aligned in tandem, representing an uncommon situation in fishes. The results obtained reinforce the basal condition of the ZZ/ZW sex system in the genus Triportheus, probably arisen prior to speciation in the group.

  8. A study to review sex ratio at birth and analyze preferences for the sex of the unborn.

    Science.gov (United States)

    Warade, Yugali; Balsarkar, Geetha; Bandekar, Pooja

    2014-02-01

    (1) To study the status of sex ratio at birth with increasing birth order, (2) To ascertain the relationship of declining sex ratio with respect to socio demographic factors. (3) To study outlook of patient towards sex preference, willingness to determine sex of the fetus, wish to terminate the pregnancy in case of unwanted sex of the baby. This is the retrospective study done in the Department of Obstetrics and Gynaecology, Nowrosjee Wadia Maternity Hospital, Parel, Mumbai. The data was collected from the records maintained in Medical Record Department from January 2007 to December 2012 and were studied to determine the sex ratio as well as its relationship with the increasing parity. 95 % confidence interval for the sex ratios was calculated. Average sex ratio of 6 years was 908 females per 1,000 males. Sex ratio was 972 females per 1,000 males in primi para, which decreased to 879 females per 1,000 males in second para, further reduced to 784 females per 1,000 males in third para and 864 females per 1,000 males in fourth para. The 'sex ratio at birth', defined as the number of girls born for every 1,000 boys born, is a more accurate and refined indicator of the extent of prenatal sex selection.

  9. Empirical evidence for son-killing X chromosomes and the operation of SA-zygotic drive.

    Science.gov (United States)

    Friberg, Urban; Stewart, Andrew D; Rice, William R

    2011-01-01

    Diploid organisms have two copies of all genes, but only one is carried by each haploid gamete and diploid offspring. This causes a fundamental genetic conflict over transmission rate between alternative alleles. Single genes, or gene clusters, only rarely code for the complex phenotypes needed to give them a transmission advantage (drive phenotype). However, all genes on a male's X and Y chromosomes co-segregate, allowing different sex-linked genes to code for different parts of the drive phenotype. Correspondingly, the well-characterized phenomenon of male gametic drive, occurring during haploid gametogenesis, is especially common on sex chromosomes. The new theory of sexually antagonistic zygotic drive of the sex chromosomes (SA-zygotic drive) extends the logic of gametic drive into the diploid phase of the lifecycle, whenever there is competition among siblings or harmful sib-sib mating. The X and Y are predicted to gain a transmission advantage by harming offspring of the sex that does not carry them. Here we analyzed a mutant X-chromosome in Drosophila simulans that produced an excess of daughters when transmitted from males. We developed a series of tests to differentiate between gametic and SA-zygotic drive, and provide multiple lines of evidence that SA-zygotic drive is responsible for the sex ratio bias. Driving sires produce about 50% more surviving daughters than sons. Sex-ratio distortion due to genetic conflict has evolved via gametic drive and maternally transmitted endosymbionts. Our data indicate that sex chromosomes can also drive by harming the non-carrier sex of offspring.

  10. Empirical evidence for son-killing X chromosomes and the operation of SA-zygotic drive.

    Directory of Open Access Journals (Sweden)

    Urban Friberg

    Full Text Available Diploid organisms have two copies of all genes, but only one is carried by each haploid gamete and diploid offspring. This causes a fundamental genetic conflict over transmission rate between alternative alleles. Single genes, or gene clusters, only rarely code for the complex phenotypes needed to give them a transmission advantage (drive phenotype. However, all genes on a male's X and Y chromosomes co-segregate, allowing different sex-linked genes to code for different parts of the drive phenotype. Correspondingly, the well-characterized phenomenon of male gametic drive, occurring during haploid gametogenesis, is especially common on sex chromosomes. The new theory of sexually antagonistic zygotic drive of the sex chromosomes (SA-zygotic drive extends the logic of gametic drive into the diploid phase of the lifecycle, whenever there is competition among siblings or harmful sib-sib mating. The X and Y are predicted to gain a transmission advantage by harming offspring of the sex that does not carry them.Here we analyzed a mutant X-chromosome in Drosophila simulans that produced an excess of daughters when transmitted from males. We developed a series of tests to differentiate between gametic and SA-zygotic drive, and provide multiple lines of evidence that SA-zygotic drive is responsible for the sex ratio bias. Driving sires produce about 50% more surviving daughters than sons.Sex-ratio distortion due to genetic conflict has evolved via gametic drive and maternally transmitted endosymbionts. Our data indicate that sex chromosomes can also drive by harming the non-carrier sex of offspring.

  11. Psychological distress during early gestation and offspring sex ratio

    DEFF Research Database (Denmark)

    Obel, C; Henriksen, TB; Secher, Niels Jørgen

    2007-01-01

    BACKGROUND: Exposure to severe stress in early pregnancy is associated with a lower male to female ratio (sex ratio), but whether more moderate levels of psychological discomfort have the same kind of effect is unknown. In a population based follow-up study, we aimed to test whether psychological...... suggest that not only severe stress, but also more moderate and common levels of psychological distress, may decrease the sex ratio in the offspring. Stress during pregnancy is a likely candidate involved in the decreasing sex ratio observed in many countries....... distress was associated with the sex ratio in the offspring. METHODS: From 1989 to 1992, a cohort of 8,719 Danish-speaking pregnant women were followed until delivery. Questionnaires were administered to the women in early pregnancy and 6,629 (76%) completed the 30-item version of the General Health...

  12. Psychological distress during early gestation and offspring sex ratio

    DEFF Research Database (Denmark)

    Obel, Carsten; Henriksen, Tine Brink; Secher, Niels Jørgen

    2007-01-01

    BACKGROUND: Exposure to severe stress in early pregnancy is associated with a lower male to female ratio (sex ratio), but whether more moderate levels of psychological discomfort have the same kind of effect is unknown. In a population based follow-up study, we aimed to test whether psychological...... suggest that not only severe stress, but also more moderate and common levels of psychological distress, may decrease the sex ratio in the offspring. Stress during pregnancy is a likely candidate involved in the decreasing sex ratio observed in many countries. Udgivelsesdato: 2007-Nov...... distress was associated with the sex ratio in the offspring. METHODS: From 1989 to 1992, a cohort of 8,719 Danish-speaking pregnant women were followed until delivery. Questionnaires were administered to the women in early pregnancy and 6,629 (76%) completed the 30-item version of the General Health...

  13. Meiotic sex ratio variation in natural populations of Ceratodon purpureus (Ditrichaceae).

    Science.gov (United States)

    Norrell, Tatum E; Jones, Kelly S; Payton, Adam C; McDaniel, Stuart F

    2014-09-01

    Sex ratio variation is a common but often unexplained phenomenon in species across the tree of life. Here we evaluate the hypothesis that meiotic sex ratio variation can contribute to the biased sex ratios found in natural populations of the moss Ceratodon purpureus.• We obtained sporophytes from several populations of C. purpureus from eastern North America. From each sporophyte, we estimated the mean spore viability by germinating replicate samples on agar plates. We estimated the meiotic sex ratio of each sporophyte by inferring the sex of a random sample of germinated spores (mean = 77) using a PCR-RFLP test. We tested for among-sporophyte variation in viability using an ANOVA and for deviations from 1:1 sex ratio using a χ(2)-test and evaluated the relationship between these quantities using a linear regression.• We found among-sporophyte variation in spore viability and meiotic sex ratio, suggesting that genetic variants that contribute to variation in both of these traits segregate within populations of this species. However, we found no relationship between these quantities, suggesting that factors other than sex ratio distorters contribute to variation in spore viability within populations.• These results demonstrate that sex ratio distortion may partially explain the population sex ratio variation seen in C. purpureus, but more generally that genetic conflict over meiotic segregation may contribute to fitness variation in this species. Overall, this study lays the groundwork for future studies on the genetic basis of meiotic sex ratio variation. © 2014 Botanical Society of America, Inc.

  14. An immunological approach of sperm sexing and different methods for identification of X- and Y-chromosome bearing sperm

    Directory of Open Access Journals (Sweden)

    Shiv Kumar Yadav

    2017-05-01

    Full Text Available Separation of X- and Y-chromosome bearing sperm has been practiced for selection of desired sex of offspring to increase the profit in livestock industries. At present, fluorescence-activated cell sorter is the only successful method for separation of X- and Y-chromosome bearing sperm. This technology is based on the differences in DNA content between these two types of sperm and has been commercialized for bovine sperm. However, this technology still has problems in terms of high economic cost, sperm damage, and lower pregnancy rates compared to unsorted semen. Therefore, an inexpensive, convenient, and non-invasive approach for sperm sexing would be of benefit to agricultural sector. Within this perspective, immunological sperm sexing method is one of the attractive choices to separate X- and Y-chromosome bearing sperm. This article reviews the current knowledge about immunological approaches, viz., H-Y antigen, sex-specific antigens, and differentially expressed proteins for sperm sexing. Moreover, this review also highlighted the different methods for identification of X- and Y-sperm.

  15. Sex ratios in fetuses and liveborn infants with autosomal aneuploidy

    Energy Technology Data Exchange (ETDEWEB)

    Heuther, C.A.; Martin, R.L.M.; Stoppelman, S.M. [Univ. of Cincinnati, OH (United States)] [and others

    1996-06-14

    Ten data sources were used substantially to increase the available data for estimating fetal and livebirth sex ratios for Patau (trisomy 13), Edwards (trisomy 18), and Down (trisomy 21) syndromes and controls. The fetal sex ratio estimate was 0.88 (N = 584) for trisomy 13, 0.90 (N = 1702) for trisomy 18, and 1.16 (N = 3154) for trisomy 21. All were significantly different from prenatal controls (1.07). The estimated ratios in prenatal controls were 1.28 (N = 1409) for CVSs and 1.06 (N = 49427) for amniocenteses, indicating a clear differential selection against males, mostly during the first half of fetal development. By contrast, there were no sex ratio differences for any of the trisomies when comparing gestational ages <16 and >16 weeks. The livebirth sex ratio estimate was 0.90 (N = 293) for trisomy 13, 0.63 (N = 497) for trisomy 18, and 1.15 (N = 6424) for trisomy 21, the latter two being statistically different than controls (1.05) (N = 3660707). These ratios for trisomies 13 and 18 were also statistically different than the ratio for trisomy 21. Only in trisomy 18 did the sex ratios in fetuses and livebirths differ, indicating a prenatal selection against males >16 weeks. No effects of maternal age or race were found on these estimates for any of the fetal or livebirth trisomies. Sex ratios for translocations and mosaics were also estimated for these aneuploids. Compared to previous estimates, these results are less extreme, most likely because of larger sample sizes and less sample bias. They support the hypothesis that these trisomy sex ratios are skewed at conception, or become so during embryonic development through differential intrauterine selection. The estimate for Down syndrome livebirths is also consistent with the hypothesis that its higher sex ratio is associated with paternal nondisjunction. 36 refs., 5 tabs.

  16. Dissociable effects of Sry and sex chromosome complement on activity, feeding and anxiety-related behaviours in mice.

    Science.gov (United States)

    Kopsida, Eleni; Lynn, Phoebe M; Humby, Trevor; Wilkinson, Lawrence S; Davies, William

    2013-01-01

    Whilst gonadal hormones can substantially influence sexual differentiation of the brain, recent findings have suggested that sex-linked genes may also directly influence neurodevelopment. Here we used the well-established murine 'four core genotype' (FCG) model on a gonadally-intact, outbred genetic background to characterise the contribution of Sry-dependent effects (i.e. those arising from the expression of the Y-linked Sry gene in the brain, or from hormonal sequelae of gonadal Sry expression) and direct effects of sex-linked genes other than Sry ('sex chromosome complement' effects) to sexually dimorphic mouse behavioural phenotypes. Over a 24 hour period, XX and XY gonadally female mice (lacking Sry) exhibited greater horizontal locomotor activity and reduced food consumption per unit bodyweight than XX and XY gonadally male mice (possessing Sry); in two behavioural tests (the elevated plus and zero mazes) XX and XY gonadally female mice showed evidence for increased anxiety-related behaviours relative to XX and XY gonadally male mice. Exploratory correlational analyses indicated that these Sry-dependent effects could not be simply explained by brain expression of the gene, nor by circulating testosterone levels. We also noted a sex chromosome complement effect on food (but not water) consumption whereby XY mice consumed more over a 24hr period than XX mice, and a sex chromosome complement effect in a third test of anxiety-related behaviour, the light-dark box. The present data suggest that: i) the male-specific factor Sry may influence activity and feeding behaviours in mice, and ii) dissociable feeding and anxiety-related murine phenotypes may be differentially modulated by Sry and by other sex-linked genes. Our results may have relevance for understanding the molecular underpinnings of sexually dimorphic behavioural phenotypes in healthy men and women, and in individuals with abnormal sex chromosome constitutions.

  17. Dissociable effects of Sry and sex chromosome complement on activity, feeding and anxiety-related behaviours in mice.

    Directory of Open Access Journals (Sweden)

    Eleni Kopsida

    Full Text Available Whilst gonadal hormones can substantially influence sexual differentiation of the brain, recent findings have suggested that sex-linked genes may also directly influence neurodevelopment. Here we used the well-established murine 'four core genotype' (FCG model on a gonadally-intact, outbred genetic background to characterise the contribution of Sry-dependent effects (i.e. those arising from the expression of the Y-linked Sry gene in the brain, or from hormonal sequelae of gonadal Sry expression and direct effects of sex-linked genes other than Sry ('sex chromosome complement' effects to sexually dimorphic mouse behavioural phenotypes. Over a 24 hour period, XX and XY gonadally female mice (lacking Sry exhibited greater horizontal locomotor activity and reduced food consumption per unit bodyweight than XX and XY gonadally male mice (possessing Sry; in two behavioural tests (the elevated plus and zero mazes XX and XY gonadally female mice showed evidence for increased anxiety-related behaviours relative to XX and XY gonadally male mice. Exploratory correlational analyses indicated that these Sry-dependent effects could not be simply explained by brain expression of the gene, nor by circulating testosterone levels. We also noted a sex chromosome complement effect on food (but not water consumption whereby XY mice consumed more over a 24hr period than XX mice, and a sex chromosome complement effect in a third test of anxiety-related behaviour, the light-dark box. The present data suggest that: i the male-specific factor Sry may influence activity and feeding behaviours in mice, and ii dissociable feeding and anxiety-related murine phenotypes may be differentially modulated by Sry and by other sex-linked genes. Our results may have relevance for understanding the molecular underpinnings of sexually dimorphic behavioural phenotypes in healthy men and women, and in individuals with abnormal sex chromosome constitutions.

  18. X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus

    Directory of Open Access Journals (Sweden)

    Adauto Lima Cardoso

    2015-06-01

    Full Text Available Several types of sex chromosome systems have been recorded among Gymnotiformes, including male and female heterogamety, simple and multiple sex chromosomes, and different mechanisms of origin and evolution. The X1X1X2X2/X1X2Y systems identified in three species of this order are considered homoplasic for the group. In the genus Brachyhypopomus, only B. gauderio presented this type of system. Herein we describe the karyotypes of Brachyhypopomus pinnicaudatus and B. n. sp. FLAV, which have an X1X1X2X2/X1X2Y sex chromosome system that evolved via fusion between an autosome and the Y chromosome. The morphology of the chromosomes and the meiotic pairing suggest that the sex chromosomes of B. gauderio and B. pinnicaudatus have a common origin, whereas in B . n. sp. FLAV the sex chromosome system evolved independently. However, we cannot discard the possibility of common origin followed by distinct processes of differentiation. The identification of two new karyotypes with an X1X1X2X2/X1X2Y sex chromosome system in Gymnotiformes makes it the most common among the karyotyped species of the group. Comparisons of these karyotypes and the evolutionary history of the taxa indicate independent origins for their sex chromosomes systems. The recurrent emergence of the X1X1X2X2/X1X2Y system may represent sex chromosomes turnover events in Gymnotiformes.

  19. Abnormal sex chromosome constitution and longitudinal growth: serum levels of insulin-like growth factor (IGF)-I, IGF binding protein-3, luteinizing hormone, and testosterone in 109 males with 47,XXY, 47,XYY, or sex-determining region of the Y chromosome (SRY)-positive 46,XX karyotypes

    DEFF Research Database (Denmark)

    Aksglaede, L.; Skakkebaek, N.E.; Juul, A.

    2008-01-01

    CONTEXT: Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles. AIM: The aim of the study was to evaluate the role of abnormal chromosome constitution for longitu......CONTEXT: Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles. AIM: The aim of the study was to evaluate the role of abnormal chromosome constitution...... and sitting height, serum levels of reproductive hormones, IGF-I, and IGFBP-3 were measured. RESULTS: In boys with 47,XXY and 47,XYY karyotypes, growth was accelerated already in childhood, compared with healthy boys. 46,XX-males were significantly shorter than healthy boys but matched the stature of healthy...... and elevated LH levels after puberty, whereas the sex hormone secretion of the 47,XYY boys remained normal. CONCLUSION: We found accelerated growth in early childhood in boys with 47,XXY and 47,XYY karyotypes, whereas 46,XX-males were shorter than controls. These abnormal growth patterns were not reflected...

  20. A new physical mapping approach refines the sex-determining gene positions on the Silene latifolia Y-chromosome

    Science.gov (United States)

    Kazama, Yusuke; Ishii, Kotaro; Aonuma, Wataru; Ikeda, Tokihiro; Kawamoto, Hiroki; Koizumi, Ayako; Filatov, Dmitry A.; Chibalina, Margarita; Bergero, Roberta; Charlesworth, Deborah; Abe, Tomoko; Kawano, Shigeyuki

    2016-01-01

    Sex chromosomes are particularly interesting regions of the genome for both molecular genetics and evolutionary studies; yet, for most species, we lack basic information, such as the gene order along the chromosome. Because they lack recombination, Y-linked genes cannot be mapped genetically, leaving physical mapping as the only option for establishing the extent of synteny and homology with the X chromosome. Here, we developed a novel and general method for deletion mapping of non-recombining regions by solving “the travelling salesman problem”, and evaluate its accuracy using simulated datasets. Unlike the existing radiation hybrid approach, this method allows us to combine deletion mutants from different experiments and sources. We applied our method to a set of newly generated deletion mutants in the dioecious plant Silene latifolia and refined the locations of the sex-determining loci on its Y chromosome map.

  1. Genome-wide association study uncovers a novel QTL allele of AtS40-3 that affects the sex ratio of cyst nematodes in Arabidopsis.

    Science.gov (United States)

    Anwer, Muhammad Arslan; Anjam, Muhammad Shahzad; Shah, Syed Jehangir; Hasan, M Shamim; Naz, Ali A; Grundler, Florian M W; Siddique, Shahid

    2018-03-24

    Plant-parasitic cyst nematodes are obligate sedentary parasites that infect the roots of a broad range of host plants. Cyst nematodes are sexually dimorphic, but differentiation into male or female is strongly influenced by interactions with the host environment. Female populations typically predominate under favorable conditions, whereas male populations predominate under adverse conditions. Here, we performed a genome-wide association study (GWAS) in an Arabidopsis diversity panel to identify host loci underlying variation in susceptibility to cyst nematode infection. Three different susceptibility parameters were examined, with the aim of providing insights into the infection process, the number of females and males present in the infected plant, and the female-to-male sex ratio. GWAS results suggested that variation in sex ratio is associated with a novel quantitative trait locus allele on chromosome 4. Subsequent candidate genes and functional analyses revealed that a senescence-associated transcription factor, AtS40-3, and PPR may act in combination to influence nematode sex ratio. A detailed molecular characterization revealed that variation in nematode sex ratio was due to the disturbed common promoter of AtS40-3 and PPR genes. Additionally, single nucleotide polymorphisms in the coding sequence of AtS40-3 might contribute to the natural variation in nematode sex ratio.

  2. Genetic markers, translocations and sexing genes on chromosome 2 of Ceratitis capitata

    International Nuclear Information System (INIS)

    Cladera, J.L.

    1997-01-01

    A review is presented of results obtained in a search for genetic markers, translocations and selectable genes obtained at the Instituto de Genetica, Castelar, Argentina, with special reference to chromosome 2 linked mutations and genes useful for developing self-sexing strains in Ceratitis capitata. (author)

  3. Sex chromosome trisomies in Europe: prevalence, prenatal detection and outcome of pregnancy

    DEFF Research Database (Denmark)

    Boyd, Patricia Anne; Loane, Maria; Garne, Ester

    2011-01-01

    This study aims to assess prevalence and pregnancy outcome for sex chromosome trisomies (SCTs) diagnosed prenatally or in the first year of life. Data held by the European Surveillance of Congenital Anomalies (EUROCAT) database on SCT cases delivered 2000-2005 from 19 population-based registries ...

  4. THE ENIGMA OF ETHIOPIAN SEX RATIOS AT BIRTH.

    Science.gov (United States)

    Garenne, Michel

    2017-09-01

    This study analysed sex ratios at birth (defined as the number of male births per 100 female births) using data on children ever-born from three censuses conducted in Ethiopia in 1984, 1994 and 2007. The results showed very high values by any standard, with an average of 108.4 for a sample of some 8.2 million births, with somewhat lower values in urban areas. Analysis of socioeconomic correlates revealed that the sex ratio varied very much by household wealth, from about 110 for very poor women to about 102 for wealthier women. The high value of the sex ratio at birth in Ethiopia could be explained by poverty, used as a proxy for poor nutritional status. In multivariate analysis, the effects of living in urban areas and of maternal education were less important than household wealth. Among the many ethno-linguistic groups, the Nilotic family had higher sex ratios than other groups. The results were confirmed using data from DHS surveys conducted in the country, and by the analysis of children still living at time of census.

  5. Serum levels of perfluorinated compounds and sperm Y:X chromosome ratio in two European populations and in Inuit from Greenland

    DEFF Research Database (Denmark)

    Kvist, Linus; Giwercman, Yvonne Lundberg; Jönsson, Bo A G

    2012-01-01

    and PFOS were measured in 607 men from Greenland, Poland and Ukraine using liquid chromatography-tandem mass spectrometry. Data was analyzed by linear and nonlinear regression. We observed no associations between PFOA and Y:X ratio (p=0.845 in a linear model, p=0.296 in a nonlinear model). A positive......This study investigated whether perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), which exhibit reproductive toxicity in experimental animals, affect sperm sex chromosome ratio. The Y:X ratio was determined by fluorescence in situ hybridization. Serum concentrations of PFOA...... nonlinear association between PFOS and Y:X ratio was observed (p=0.016), with no association in a linear model (p=0.118). Analyzing the populations separately, a negative trend between categorized PFOS exposure and Y:X ratio was observed for the Inuit (B=-0.002, p=0.044). In conclusion, there was a negative...

  6. Unusual distribution of Zfy and Zfx sequences on the sex chromosomes of the wood lemming, a species exhibiting XY sex reversal.

    Science.gov (United States)

    Lau, Y F; Yang-Feng, T L; Elder, B; Fredga, K; Wiberg, U H

    1992-01-01

    Sex reversal occurs naturally in the wood lemming (Myopus schisticolor) due to the presence in populations of this species of a variant (mutated) X chromosome, designated X*. Thus, X*Y animals develop into females, whereas XY animals develop into normal males. Chromosome mapping by in situ hybridization of DNA sequences homologous to the human ZFY gene localized the wood lemming Zfx sequences to region p12----p11 on both the wild-type X and the mutated X* chromosomes, at or proximal to a presumed breakpoint (Xp12) involved in the generation of the X* chromosome from the normal X, and Zfy sequences along the entire short arm of the Y chromosome. Differences between Zfx and Zfx* were readily detected by Southern blot analysis. However, both the Zfx and Zfx* genes expressed similarly sized transcripts in all adult somatic tissues investigated. Although the precise molecular difference between the Zfx and Zfx* genes is still unknown, their chromosomal location suggests that either Zfx or some other closely linked gene(s) on the X chromosome may be a major X-linked sex-determining gene, Tdx, which in the X* chromosome fails to interact properly with the Y-linked testis-determining gene, Tdy, thus causing X*Y embryos to develop into females. At least 15 copies of wood lemming Zfy sequences are distributed along the short arm of the Y chromosome. Northern hybridization analyses of adult tissues and somatic cell lines indicated that these Zfy repeats were transcriptionally inactive. Normally, 3-kb Zfy (ZFY) transcripts are readily detected in mouse and human testes, especially in the germ cells. It has therefore been postulated that expression of the Zfy (ZFY) gene may be important for spermatogenesis. Whether the lack of sufficient Zfy transcripts in the testis of the adult wood lemming has any impact on spermatogenesis in this species is still to be elucidated by further studies.

  7. Neo-sex chromosomes in the monarch butterfly, Danaus plexippus

    Czech Academy of Sciences Publication Activity Database

    Mongue, A. J.; Nguyen, Petr; Voleníková, Anna; Walters, J. R.

    2017-01-01

    Roč. 7, č. 10 (2017), s. 3281-3294 ISSN 2160-1836 R&D Projects: GA ČR(CZ) GA14-22765S; GA ČR(CZ) GP14-35819P Grant - others:GA JU(CZ) 159/2016/P Institutional support: RVO:60077344 Keywords : sex chromosomes * evolution * Lepidoptera Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 2.861, year: 2016 http://www.g3journal.org/content/7/10/3281.long

  8. Chromosomal divergence and evolutionary inferences in Rhodniini based on the chromosomal location of ribosomal genes

    Directory of Open Access Journals (Sweden)

    Sebastian Pita

    2013-05-01

    Full Text Available In this study, we used fluorescence in situ hybridisation to determine the chromosomal location of 45S rDNA clusters in 10 species of the tribe Rhodniini (Hemiptera: Reduviidae: Triatominae. The results showed striking inter and intraspecific variability, with the location of the rDNA clusters restricted to sex chromosomes with two patterns: either on one (X chromosome or both sex chromosomes (X and Y chromosomes. This variation occurs within a genus that has an unchanging diploid chromosome number (2n = 22, including 20 autosomes and 2 sex chromosomes and a similar chromosome size and genomic DNA content, reflecting a genome dynamic not revealed by these chromosome traits. The rDNA variation in closely related species and the intraspecific polymorphism in Rhodnius ecuadoriensis suggested that the chromosomal position of rDNA clusters might be a useful marker to identify recently diverged species or populations. We discuss the ancestral position of ribosomal genes in the tribe Rhodniini and the possible mechanisms involved in the variation of the rDNA clusters, including the loss of rDNA loci on the Y chromosome, transposition and ectopic pairing. The last two processes involve chromosomal exchanges between both sex chromosomes, in contrast to the widely accepted idea that the achiasmatic sex chromosomes of Heteroptera do not interchange sequences.

  9. Parental correlates of offspring sex ratio in Eurasian Oystercatchers

    NARCIS (Netherlands)

    Heg, D.; Dingemanse, NJ; Lessells, CM; Mateman, AC

    2000-01-01

    We investigated hatchling and fledgling sex ratios in Eurasian Oystercatchers (Haematopus ostralegus) using random amplified polymorphic DNA markers. The overall hatchling (53% males, n = 374 hatchlings from 177 broods) and fledgling (49% males, n = 51) sex ratio did not differ significantly from

  10. Human sex ratio at amniocentesis and at birth in Taiwan

    Directory of Open Access Journals (Sweden)

    I-Wen Lee

    2012-12-01

    Conclusions: The results showed that sex ratio was already skewed toward male at midtrimester. Our data imply that artificial sex selection, if it were present, might have already emerged prior to the timing of amniocentesis. However, more large nationwide studies on sex ratios in Taiwan are warranted.

  11. Genomic diversity in two related plant species with and without sex chromosomes--Silene latifolia and S. vulgaris.

    Directory of Open Access Journals (Sweden)

    Radim Cegan

    Full Text Available Genome size evolution is a complex process influenced by polyploidization, satellite DNA accumulation, and expansion of retroelements. How this process could be affected by different reproductive strategies is still poorly understood.We analyzed differences in the number and distribution of major repetitive DNA elements in two closely related species, Silene latifolia and S. vulgaris. Both species are diploid and possess the same chromosome number (2n = 24, but differ in their genome size and mode of reproduction. The dioecious S. latifolia (1C = 2.70 pg DNA possesses sex chromosomes and its genome is 2.5× larger than that of the gynodioecious S. vulgaris (1C = 1.13 pg DNA, which does not possess sex chromosomes. We discovered that the genome of S. latifolia is larger mainly due to the expansion of Ogre retrotransposons. Surprisingly, the centromeric STAR-C and TR1 tandem repeats were found to be more abundant in S. vulgaris, the species with the smaller genome. We further examined the distribution of major repetitive sequences in related species in the Caryophyllaceae family. The results of FISH (fluorescence in situ hybridization on mitotic chromosomes with the Retand element indicate that large rearrangements occurred during the evolution of the Caryophyllaceae family.Our data demonstrate that the evolution of genome size in the genus Silene is accompanied by the expansion of different repetitive elements with specific patterns in the dioecious species possessing the sex chromosomes.

  12. Sex ratio in two species of Pegoscapus wasps (Hymenoptera: Agaonidae) that develop in figs: can wasps do mathematics, or play sex ratio games?

    Science.gov (United States)

    Ramírez-Benavides, William; Monge-Nájera, Julián; Chavarría, Juan B

    2009-09-01

    The fig pollinating wasps (Hymenoptera: Agaonidae) have obligate arrhenotoky and a breeding structure that fits local mate competition (LMC). It has been traditionally assumed that LMC organisms adjust the sex ratio by laying a greater proportion of male eggs when there is superparasitism (several foundresses in a host). We tested the assumption with two wasp species, Pegoscapus silvestrii, pollinator of Ficus pertusa and Pegoscapus tonduzi, pollinator of Ficus eximia (= F citrifolia), in the Central Valley of Costa Rica. Total number of wasps and seeds were recorded in individual isolated naturally colonized syconia. There was a constant additive effect between the number of foundresses and the number of males produced in the brood of a syconium, while the number of females decreased. Both wasp species seem to have precise sex ratios and probably lay the male eggs first in the sequence, independently of superparasitism and clutch size: consequently, they have a non-random sex allocation. Each syconium of Ficus pertusa and of F. eximia colonized by one foundress had similar mean numbers of females, males, and seeds. The two species of wasps studied do not seem to adjust the sex ratio when there is superparasitism. Pollinating fig wasp behavior is better explained by those models not assuming that females do mathematical calculations according to other females' sex ratios, size, number of foundresses, genetic constitution, clutch size or environmental conditions inside the syconium. Our results are in agreement with the constant male number hypothesis, not with sex ratio games.

  13. Breeding sex ratio and population size of loggerhead turtles from Southwestern Florida.

    Directory of Open Access Journals (Sweden)

    Jacob A Lasala

    Full Text Available Species that display temperature-dependent sex determination are at risk as a result of increasing global temperatures. For marine turtles, high incubation temperatures can skew sex ratios towards females. There are concerns that temperature increases may result in highly female-biased offspring sex ratios, which would drive a future sex ratio skew. Studying the sex ratios of adults in the ocean is logistically very difficult because individuals are widely distributed and males are inaccessible because they remain in the ocean. Breeding sex ratios (BSR are sought as a functional alternative to study adult sex ratios. One way to examine BSR is to determine the number of males that contribute to nests. Our goal was to evaluate the BSR for loggerhead turtles (Caretta caretta nesting along the eastern Gulf of Mexico in Florida, from 2013-2015, encompassing three nesting seasons. We genotyped 64 nesting females (approximately 28% of all turtles nesting at that time and up to 20 hatchlings from their nests (n = 989 using 7 polymorphic microsatellite markers. We identified multiple paternal contributions in 70% of the nests analyzed and 126 individual males. The breeding sex ratio was approximately 1 female for every 2.5 males. We did not find repeat males in any of our nests. The sex ratio and lack of repeating males was surprising because of female-biased primary sex ratios. We hypothesize that females mate offshore of their nesting beaches as well as en route. We recommend further comparisons of subsequent nesting events and of other beaches as it is imperative to establish baseline breeding sex ratios to understand how growing populations behave before extreme environmental effects are evident.

  14. Multiple sex chromosomes in the light of female meiotic drive in amniote vertebrates

    Czech Academy of Sciences Publication Activity Database

    Pokorná, Martina; Altmanová, M.; Kratochvíl, L.

    2014-01-01

    Roč. 22, č. 1 (2014), s. 35-44 ISSN 0967-3849 R&D Projects: GA ČR GAP506/10/0718 Institutional support: RVO:67985904 Keywords : amniota * centromere * heterogamety * neo-sex chromosomes * reptiles Subject RIV: EG - Zoology Impact factor: 2.478, year: 2014

  15. A heritable component in sex ratio and caste determination in a Cardiocondyla ant

    Directory of Open Access Journals (Sweden)

    Heinze Jürgen

    2009-10-01

    Full Text Available Abstract Studies on sex ratios in social insects provide among the most compelling evidence for the importance of kin selection in social evolution. The elegant synthesis of Fisher's sex ratio principle and Hamilton's inclusive fitness theory predicts that colony-level sex ratios vary with the colonies' social and genetic structures. Numerous empirical studies in ants, bees, and wasps have corroborated these predictions. However, the evolutionary optimization of sex ratios requires genetic variation, but one fundamental determinant of sex ratios - the propensity of female larvae to develop into young queens or workers ("queen bias" - is thought to be largely controlled by the environment. Evidence for a genetic influence on sex ratio and queen bias is as yet restricted to a few taxa, in particular hybrids. Because of the very short lifetime of their queens, ants of the genus Cardiocondyla are ideal model systems for the study of complete lifetime reproductive success, queen bias, and sex ratios. We found that lifetime sex ratios of the ant Cardiocondyla kagutsuchi have a heritable component. In experimental single-queen colonies, 22 queens from a genetic lineage with a highly female-biased sex ratio produced significantly more female-biased offspring sex ratios than 16 queens from a lineage with a more male-biased sex ratio (median 91.5% vs. 58.5% female sexuals. Sex ratio variation resulted from different likelihood of female larvae developing into sexuals (median 50% vs. 22.6% female sexuals even when uniformly nursed by workers from another colony. Consistent differences in lifetime sex ratios and queen bias among queens of C. kagutsuchi suggest that heritable, genetic or maternal effects strongly affect caste determination. Such variation might provide the basis for adaptive evolution of queen and worker strategies, though it momentarily constrains the power of workers and queens to optimize caste ratios.

  16. A heritable component in sex ratio and caste determination in a Cardiocondyla ant.

    Science.gov (United States)

    Frohschammer, Sabine; Heinze, Jürgen

    2009-10-28

    Studies on sex ratios in social insects provide among the most compelling evidence for the importance of kin selection in social evolution. The elegant synthesis of Fisher's sex ratio principle and Hamilton's inclusive fitness theory predicts that colony-level sex ratios vary with the colonies' social and genetic structures. Numerous empirical studies in ants, bees, and wasps have corroborated these predictions. However, the evolutionary optimization of sex ratios requires genetic variation, but one fundamental determinant of sex ratios - the propensity of female larvae to develop into young queens or workers ("queen bias") - is thought to be largely controlled by the environment. Evidence for a genetic influence on sex ratio and queen bias is as yet restricted to a few taxa, in particular hybrids.Because of the very short lifetime of their queens, ants of the genus Cardiocondyla are ideal model systems for the study of complete lifetime reproductive success, queen bias, and sex ratios. We found that lifetime sex ratios of the ant Cardiocondyla kagutsuchi have a heritable component. In experimental single-queen colonies, 22 queens from a genetic lineage with a highly female-biased sex ratio produced significantly more female-biased offspring sex ratios than 16 queens from a lineage with a more male-biased sex ratio (median 91.5% vs. 58.5% female sexuals). Sex ratio variation resulted from different likelihood of female larvae developing into sexuals (median 50% vs. 22.6% female sexuals) even when uniformly nursed by workers from another colony.Consistent differences in lifetime sex ratios and queen bias among queens of C. kagutsuchi suggest that heritable, genetic or maternal effects strongly affect caste determination. Such variation might provide the basis for adaptive evolution of queen and worker strategies, though it momentarily constrains the power of workers and queens to optimize caste ratios.

  17. Sex ratio at birth in India, its relation to birth order, sex of previous children and use of indigenous medicine.

    Directory of Open Access Journals (Sweden)

    Samiksha Manchanda

    Full Text Available OBJECTIVE: Sex-ratio at birth in families with previous girls is worse than those with a boy. Our aim was to prospectively study in a large maternal and child unit sex-ratio against previous birth sex and use of traditional medicines for sex selection. MAIN OUTCOME MEASURES: Sex-ratio among mothers in families with a previous girl and in those with a previous boy, prevalence of indigenous medicine use and sex-ratio in those using medicines for sex selection. RESULTS: Overall there were 806 girls to 1000 boys. The sex-ratio was 720:1000 if there was one previous girl and 178:1000 if there were two previous girls. In second children of families with a previous boy 1017 girls were born per 1000 boys. Sex-ratio in those with one previous girl, who were taking traditional medicines for sex selection, was 928:1000. CONCLUSION: Evidence from the second children clearly shows the sex-ratio is being manipulated by human interventions. More mothers with previous girls tend to use traditional medicines for sex selection, in their subsequent pregnancies. Those taking such medication do not seem to be helped according to expectations. They seem to rely on this method and so are less likely use more definitive methods like sex selective abortions. This is the first such prospective investigation of sex ratio in second children looked at against the sex of previous children. More studies are needed to confirm the findings.

  18. Maternal preconception diet and the sex ratio

    NARCIS (Netherlands)

    Cramer, J.S.; Lumey, L.H.

    2009-01-01

    Temporal variations in the sex ratio or the ratio of boys over girls at birth have been widely studied and variously attributed to social changes, conditions of war, and environmental changes. Recently, Mathews, Johnson and Neil (2008) studied the direct evidence of individual pregnancies and

  19. Sex reversal in the mouse (Mus musculus) is caused by a recurrent nonreciprocal crossover involving the x and an aberrant y chromosome.

    Science.gov (United States)

    Singh, L; Jones, K W

    1982-02-01

    Satellite DNA (Bkm) from the W sex-determining chromosome of snakes, which is related to sequences on the mouse Y chromosome, has been used to analyze the DNA and chromosomes of sex-reversed (Sxr) XXSxr male mice. Such mice exhibit a male-specific Southern blot Bkm hybridization pattern, consistent with the presence of Y-chromosome DNA. In situ hybridization of Bkm to chromosomes of XXSxr mice shows an aberrant concentration of related sequences on the distal terminus of a large mouse chromosome. The XYSxr carrier male, however, shows a pair of small chromosomes, which are presumed to be aberrant Y derivatives. Meiosis in the XYSxr mouse involves transfer of chromatin rich in Bkm-related DNA from the Y-Y1 complex to the X distal terminus. We suggest that this event is responsible for the transmission of the Sxr trait.

  20. Using Approximate Bayesian Computation to infer sex ratios from acoustic data.

    Science.gov (United States)

    Lehnen, Lisa; Schorcht, Wigbert; Karst, Inken; Biedermann, Martin; Kerth, Gerald; Puechmaille, Sebastien J

    2018-01-01

    Population sex ratios are of high ecological relevance, but are challenging to determine in species lacking conspicuous external cues indicating their sex. Acoustic sexing is an option if vocalizations differ between sexes, but is precluded by overlapping distributions of the values of male and female vocalizations in many species. A method allowing the inference of sex ratios despite such an overlap will therefore greatly increase the information extractable from acoustic data. To meet this demand, we developed a novel approach using Approximate Bayesian Computation (ABC) to infer the sex ratio of populations from acoustic data. Additionally, parameters characterizing the male and female distribution of acoustic values (mean and standard deviation) are inferred. This information is then used to probabilistically assign a sex to a single acoustic signal. We furthermore develop a simpler means of sex ratio estimation based on the exclusion of calls from the overlap zone. Applying our methods to simulated data demonstrates that sex ratio and acoustic parameter characteristics of males and females are reliably inferred by the ABC approach. Applying both the ABC and the exclusion method to empirical datasets (echolocation calls recorded in colonies of lesser horseshoe bats, Rhinolophus hipposideros) provides similar sex ratios as molecular sexing. Our methods aim to facilitate evidence-based conservation, and to benefit scientists investigating ecological or conservation questions related to sex- or group specific behaviour across a wide range of organisms emitting acoustic signals. The developed methodology is non-invasive, low-cost and time-efficient, thus allowing the study of many sites and individuals. We provide an R-script for the easy application of the method and discuss potential future extensions and fields of applications. The script can be easily adapted to account for numerous biological systems by adjusting the type and number of groups to be

  1. First Description of the Karyotype and Sex Chromosomes in the Komodo Dragon (Varanus komodoensis)

    Czech Academy of Sciences Publication Activity Database

    Johnson Pokorná, Martina; Altmanová, M.; Rovatsos, M.; Velenský, P.; Vodička, R.; Řehák, I.; Kratochvíl, L.

    2016-01-01

    Roč. 148, č. 4 (2016), s. 284-291 ISSN 1424-8581 Institutional support: RVO:67985904 Keywords : CGH * female heterogamety * heterochromatin * microsatellite accumulation * sex chromosome evolution * squamate reptile Subject RIV: EG - Zoology Impact factor: 1.354, year: 2016

  2. Sex ratio in two species of Pegoscapus wasps (Hymenoptera: Agaonidae that develop in figs: can wasps do mathematics, or play sex ratio games?

    Directory of Open Access Journals (Sweden)

    William Ramírez-Benavides

    2009-09-01

    Full Text Available The fig pollinating wasps (Hymenoptera: Agaonidae have obligate arrhenotoky and a breeding structure that fits local mate competition (LMC. It has been traditionally assumed that LMC organisms adjust the sex ratio by laying a greater proportion of male eggs when there is superparasitism (several foundresses in a host. We tested the assumption with two wasp species, Pegoscapus silvestrii, pollinator of Ficus pertusa and Pegoscapus tonduzi, pollinator of Ficus eximia (= F. citrifolia, in the Central Valley of Costa Rica. Total number of wasps and seeds were recorded in individual isolated naturally colonized syconia. There was a constant additive effect between the number of foundresses and the number of males produced in the brood of a syconium, while the number of females decreased. Both wasp species seem to have precise sex ratios and probably lay the male eggs first in the sequence, independently of superparasitism and clutch size: consequently, they have a non-random sex allocation. Each syconium of Ficus pertusa and of F. eximia colonized by one foundress had similar mean numbers of females, males, and seeds. The two species of wasps studied do not seem to adjust the sex ratio when there is superparasitism. Pollinating fig wasp behavior is better explained by those models not assuming that females do mathematical calculations according to other females’ sex ratios, size, number of foundresses, genetic constitution, clutch size or environmental conditions inside the syconium. Our results are in agreement with the constant male number hypothesis, not with sex ratio games. Rev. Biol. Trop. 57 (3: 605-621. Epub 2009 September 30.

  3. Maternal preconception diet and the sex ratio

    NARCIS (Netherlands)

    Cramer, J.S.; Lumey, L.H.

    2010-01-01

    Temporal variations in the sex ratio, or the ratio of boys to girls at birth, have been widely studied and variously attributed to social changes, conditions of war, and environmental changes. Recently, Mathews et al. ["You are what your mother eats: Evidence for maternal preconception diet

  4. The chromosomal distribution of microsatellite repeats in the genome of the wolf fish Hoplias malabaricus, focusing on the sex chromosomes

    Czech Academy of Sciences Publication Activity Database

    Cioffi, M.B.; Kejnovský, Eduard; Bertollo, L.A.C.

    2011-01-01

    Roč. 132, č. 4 (2011), s. 289-296 ISSN 1424-8581 R&D Projects: GA ČR(CZ) GAP305/10/0930 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : fish sex chromosomes * fluorescence in situ hybridization * microsatellites Subject RIV: BO - Biophysics Impact factor: 1.533, year: 2011

  5. Sex ratio, gonadal development and fecundity of the grunt ...

    African Journals Online (AJOL)

    The sex ratio, gonadosomatic index, stages of gonadal development and fecundity of the grunt, Pomadasys jubelini in the New Calabar-Bonny River were investigated. P. jubelini had a sex ratio of 1: 2.1 (male to female). Gonadosomatic index ranged from 0.33 to 7.29% with a mean of 2.89+0.08%. High gonadosomatic ...

  6. Neither Biased Sex Ratio nor Spatial Segregation of the Sexes in the Subtropical Dioecious Tree Eurycorymbus cavaleriei (Sapindaceae)

    Institute of Scientific and Technical Information of China (English)

    Pu-xin Gao; Ming Kang; Jing Wang; Qi-gang Ye; Hong-wen Huang

    2009-01-01

    Knowledge of sex ratio and spatial distribution of males and females of dioecious species is both of evolutionary interest and of crucial importance for biological conservation. Eurycorymbus cavaleriei, the only species in the genus Eurycorymbus (Saplndaceae), is a dioecious tree endemic to subtropical montane forest in South China. Sex ratios were investigated in 15 natural populations for the two defined ages (young and old). Spatial distribution of males and females was further studied in six large populations occurring in different habitats (fragmented and continuous). The study revealed a slight trend of malebiased sex ratio in both ages of E. cavaleriei, but sex ratio of most populations (13 out of 15) did not display statistically significant deviation from equality. All of the four significantly male-biased populations in the young class shifted to equality or even female-biased. The Ripley's K analysis of the distribution of males with respect to females suggested that individuals of the opposite sexes were more randomly distributed rather than spatially structured. These results suggest that the male-biased sex ratio in E. cavaleriei may result from the precocity of males and habitat heterogeneity. The sex ratio and the sex spatial distribution pattern are unlikely to constitute a serious threat to the survival of the species.

  7. Abnormal sex chromosome constitution and longitudinal growth: serum levels of insulin-like growth factor (IGF)-I, IGF binding protein-3, luteinizing hormone, and testosterone in 109 males with 47,XXY, 47,XYY, or sex-determining region of the Y chromosome (SRY)-positive 46,XX karyotypes

    DEFF Research Database (Denmark)

    Aksglaede, L.; Skakkebaek, N.E.; Juul, A.

    2008-01-01

    CONTEXT: Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles. AIM: The aim of the study was to evaluate the role of abnormal chromosome constitution...... and elevated LH levels after puberty, whereas the sex hormone secretion of the 47,XYY boys remained normal. CONCLUSION: We found accelerated growth in early childhood in boys with 47,XXY and 47,XYY karyotypes, whereas 46,XX-males were shorter than controls. These abnormal growth patterns were not reflected...

  8. Sex Reversal and Comparative Data Undermine the W Chromosome and Support Z-linked DMRT1 as the Regulator of Gonadal Sex Differentiation in Birds.

    Science.gov (United States)

    Hirst, Claire E; Major, Andrew T; Ayers, Katie L; Brown, Rosie J; Mariette, Mylene; Sackton, Timothy B; Smith, Craig A

    2017-09-01

    The exact genetic mechanism regulating avian gonadal sex differentiation has not been completely resolved. The most likely scenario involves a dosage mechanism, whereby the Z-linked DMRT1 gene triggers testis development. However, the possibility still exists that the female-specific W chromosome may harbor an ovarian determining factor. In this study, we provide evidence that the universal gene regulating gonadal sex differentiation in birds is Z-linked DMRT1 and not a W-linked (ovarian) factor. Three candidate W-linked ovarian determinants are HINTW, female-expressed transcript 1 (FET1), and female-associated factor (FAF). To test the association of these genes with ovarian differentiation in the chicken, we examined their expression following experimentally induced female-to-male sex reversal using the aromatase inhibitor fadrozole (FAD). Administration of FAD on day 3 of embryogenesis induced a significant loss of aromatase enzyme activity in female gonads and masculinization. However, expression levels of HINTW, FAF, and FET1 were unaltered after experimental masculinization. Furthermore, comparative analysis showed that FAF and FET1 expression could not be detected in zebra finch gonads. Additionally, an antibody raised against the predicted HINTW protein failed to detect it endogenously. These data do not support a universal role for these genes or for the W sex chromosome in ovarian development in birds. We found that DMRT1 (but not the recently identified Z-linked HEMGN gene) is male upregulated in embryonic zebra finch and emu gonads, as in the chicken. As chicken, zebra finch, and emu exemplify the major evolutionary clades of birds, we propose that Z-linked DMRT1, and not the W sex chromosome, regulates gonadal sex differentiation in birds. Copyright © 2017 Endocrine Society.

  9. Sex ratios at birth after induced abortion.

    Science.gov (United States)

    Urquia, Marcelo L; Moineddin, Rahim; Jha, Prabhat; O'Campo, Patricia J; McKenzie, Kwame; Glazier, Richard H; Henry, David A; Ray, Joel G

    2016-06-14

    Skewed male:female ratios at birth have been observed among certain immigrant groups. Data on abortion practices that might help to explain these findings are lacking. We examined 1 220 933 births to women with up to 3 consecutive singleton live births between 1993 and 2012 in Ontario. Records of live births, and induced and spontaneous abortions were linked to Canadian immigration records. We determined associations of male:female infant ratios with maternal birthplace, sex of the previous living sibling(s) and prior spontaneous or induced abortions. Male:female infant ratios did not appreciably depart from the normal range among Canadian-born women and most women born outside of Canada, irrespective of the sex of previous children or the characteristics of prior abortions. However, among infants of women who immigrated from India and had previously given birth to 2 girls, the overall male:female ratio was 1.96 (95% confidence interval [CI] 1.75-2.21) for the third live birth. The male:female infant ratio after 2 girls was 1.77 (95% CI 1.26-2.47) times higher if the current birth was preceded by 1 induced abortion, 2.38 (95% CI 1.44-3.94) times higher if preceded by 2 or more induced abortions and 3.88 (95% CI 2.02-7.50) times higher if the induced abortion was performed at 15 weeks or more gestation relative to no preceding abortion. Spontaneous abortions were not associated with male-biased sex ratios in subsequent births. High male:female ratios observed among infants born to women who immigrated from India are associated with induced abortions, especially in the second trimester of pregnancy. © 2016 Canadian Medical Association or its licensors.

  10. Determining sex ratios of turtle hatchlings

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Previous status assessments of marine turtles have assumed that the natural sex ratio of a marine turtle population is 1:1 (e.g. Conant et al. 2009). However, this...

  11. Vocal and Gestural Productions of 24-Month-Old Children with Sex Chromosome Trisomies

    Science.gov (United States)

    Zampini, Laura; Draghi, Lara; Silibello, Gaia; Dall'Ara, Francesca; Rigamonti, Claudia; Suttora, Chiara; Zanchi, Paola; Salerni, Nicoletta; Lalatta, Faustina; Vizziello, Paola

    2018-01-01

    Background: Children with sex chromosome trisomies (SCT) frequently show problems in language development. However, a clear description of the communicative patterns of these children is still lacking. Aims: To describe the first stages of language development in children with SCT in comparison with those in typically developing (TD) children. The…

  12. Relationship Formation and Stability in Emerging Adulthood: Do Sex Ratios Matter?

    Science.gov (United States)

    Warner, Tara D.; Manning, Wendy D.; Giordano, Peggy C.; Longmore, Monica A.

    2011-01-01

    Research links sex ratios with the likelihood of marriage and divorce. However, whether sex ratios similarly influence precursors to marriage (transitions in and out of dating or cohabiting relationships) is unknown. Utilizing data from the Toledo Adolescent Relationships Study and the 2000 U.S. Census, this study assesses whether sex ratios…

  13. Adult sex ratio variation : Implications for breeding system evolution

    NARCIS (Netherlands)

    Szekely, T.; Weissing, F. J.; Komdeur, J.

    Adult sex ratio (ASR) exhibits immense variation in nature, although neither the causes nor the implications of this variation are fully understood. According to theory, the ASR is expected to influence sex roles and breeding systems, as the rarer sex in the population has more potential partners to

  14. Sibling sex ratio of individuals diagnosed with autism spectrum disorder as children

    DEFF Research Database (Denmark)

    Mouridsen, Svend Erik; Rich, Bente; Isager, Torben

    2010-01-01

    AIM: To study the sex ratio (proportion of males) in siblings of individuals diagnosed with autism spectrum disorders (ASDs) as children. METHOD: In the current study, we extended previous studies dealing with the androgen theory of autism and examined sex ratios in the siblings of 326 individuals...... the Danish live-birth sex ratio over the same period (0.514, p=0.001). The sibling sex ratio was not associated with the IQ in the autistic probands. INTERPRETATION: Our findings suggest a potential indirect confirmation of the androgen theory of autism....

  15. The potential pitfalls of studying adult sex ratios at aggregate levels in humans.

    Science.gov (United States)

    Pollet, Thomas V; Stoevenbelt, Andrea H; Kuppens, Toon

    2017-09-19

    Human adult sex ratios have been studied extensively across the biological and social sciences. While several studies have examined adult sex ratio effects in a multilevel perspective, many studies have focused on effects at an aggregated level only. In this paper, we review some key issues relating to such analyses. We address not only nation-level analyses, but also aggregation at lower levels, to investigate whether these issues extend to lower levels of aggregation. We illustrate these issues with novel databases covering a broad range of variables. Specifically, we discuss distributional issues with aggregated measures of adult sex ratio, significance testing, and statistical non-independence when using aggregate data. Firstly, we show that there are severe distributional issues with national adult sex ratio, such as extreme cases. Secondly, we demonstrate that many 'meaningless' variables are significantly correlated with adult sex ratio (e.g. the max. elevation level correlates with sex ratio at US state level). Finally, we re-examine associations between adult sex ratios and teenage fertility and find no robust evidence for an association at the aggregate level. Our review highlights the potential issues of using aggregate data on adult sex ratios to test hypotheses from an evolutionary perspective in humans.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

  16. Sex ratios in the Arctic--do man-made chemicals matter?

    DEFF Research Database (Denmark)

    Bjerregaard, Peter; Chatwood, Susan; Denning, Bryany

    2013-01-01

    The objective was to analyze the variation of secondary sex ratios across the Arctic and to estimate the time trend. The rationale for this was claims in news media that, in the Arctic, sex ratios have become reduced due to exposure to anthropogenic contaminants in the environment....

  17. Karyotype characterization and ZZ/ZW sex chromosome heteromorphism in two species of the catfish genus Ancistrus Kner, 1854 (Siluriformes: Loricariidae from the Amazon basin

    Directory of Open Access Journals (Sweden)

    Renildo R. de Oliveira

    Full Text Available We present karyotypic characteristics and report on the occurrence of ZZ/ZW sex chromosomes in Ancistrus ranunculus (rio Xingu and Ancistrus sp. "Piagaçu" (rio Purus, of the Brazilian Amazon. Ancistrus ranunculus has a modal number of 2n=48 chromosomes, a fundamental number (FN of 82 for both sexes, and the karyotypic formula was 20m+8sm+6st+14a for males and 19m+9sm+6st+14a for females. Ancistrus sp. "Piagaçu" presented 2n=52 chromosomes, FN= 78 for males and FN= 79 for females. The karyotypic formula was 16m+8sm+2st+26a for males and 16m+9sm+2st+25a for females. The high number of acrocentric chromosomes in karyotype of Ancistrus sp. "Piagaçu" differs from the majority of Ancistrini genera studied so far, and may have resulted from pericentric inversions and translocations. The lower number of chromosomes in A. ranunculus indicates that centric fusions also occurred in the evolution of Ancistrus karyotypes. We conclude that karyotypic characteristics and the presence of sex chromosomes can constitute important cytotaxonomic markers to identify cryptic species of Ancistrus. However, sex chromosomes apparently arose independently within the genus and thus do not constitute a reliable character to analyze phylogenetic relations among Ancistrus species.

  18. ACC oxidase and miRNA 159a, and their involvement in fresh fruit bunch yield (FFB) via sex ratio determination in oil palm.

    Science.gov (United States)

    Somyong, Suthasinee; Poopear, Supannee; Sunner, Supreet Kaur; Wanlayaporn, Kitti; Jomchai, Nukoon; Yoocha, Thippawan; Ukoskit, Kittipat; Tangphatsornruang, Sithichoke; Tragoonrung, Somvong

    2016-06-01

    Oil palm (Elaeis guineesis Jacq.) is the most productive oil-bearing crop, yielding more oil per area than any other oil-bearing crops. However, there are still efforts to improve oil palm yield, in order to serve consumer and manufacturer demand. Oil palm produces female and male inflorescences in an alternating cycle. So, high sex ratio (SR), the ratio of female inflorescences to the total inflorescences, is a favorable trait in term of increasing yields in oil palm. This study aims to understand the genetic control for SR related traits, such as fresh fruit bunch yield (FFB), by characterizing genes at FFB quantitative trait loci (QTLs) on linkage 10 (chromosome 6) and linkage 15 (chromosome 10). Published oil palm sequences at the FFB QTLs were used to develop gene-based and simple sequence repeat (SSR) markers. We used the multiple QTL analysis model (MQM) to characterize the relationship of new markers with the SR traits in the oil palm population. The RNA expression of the most linked QTL genes was also evaluated in various tissues of oil palm. We identified EgACCO1 (encoding aminocyclopropane carboxylate (ACC) oxidase) at chromosome 10 and EgmiR159a (microRNA 159a) at chromosome 6 to be the most linked QTL genes or determinants for FFB yield and/or female inflorescence number with a phenotype variance explained (PVE) from 10.4 to 15 % and suggest that these play the important roles in sex determination and differentiation in oil palm. The strongest expression of EgACCO1 and the predicted precursor of EgmiR159a was found in ovaries and, to a lesser extent, fruit development. In addition, highly normalized expression of EgmiR159a was found in female flowers. In summary, the QTL analysis and the RNA expression reveal that EgACCO1 and EgmiR159a are the potential genetic factors involved in female flower determination and hence would affect yield in oil palm. However, to clarify how these genetic factors regulate female flower determination, more investigation

  19. Uncovering the evolutionary history of neo-XY sex chromosomes in the grasshopper Ronderosia bergii (Orthoptera, Melanoplinae) through satellite DNA analysis.

    Science.gov (United States)

    Palacios-Gimenez, Octavio M; Milani, Diogo; Lemos, Bernardo; Castillo, Elio R; Martí, Dardo A; Ramos, Erica; Martins, Cesar; Cabral-de-Mello, Diogo C

    2018-01-08

    Neo-sex chromosome systems arose independently multiple times in evolution, presenting the remarkable characteristic of repetitive DNAs accumulation. Among grasshoppers, occurrence of neo-XY was repeatedly noticed in Melanoplinae. Here we analyzed the most abundant tandem repeats of R. bergii (2n = 22, neo-XY♂) using deep Illumina sequencing and graph-based clustering in order to address the neo-sex chromosomes evolution. The analyses revealed ten families of satDNAs comprising about ~1% of the male genome, which occupied mainly C-positive regions of autosomes. Regarding the sex chromosomes, satDNAs were recorded within centromeric or interstitial regions of the neo-X chromosome and four satDNAs occurred in the neo-Y, two of them being exclusive (Rber248 and Rber299). Using a combination of probes we uncovered five well-defined cytological variants for neo-Y, originated by multiple paracentric inversions and satDNA amplification, besides fragmented neo-Y. These neo-Y variants were distinct in frequency between embryos and adult males. The genomic data together with cytogenetic mapping enabled us to better understand the neo-sex chromosome dynamics in grasshoppers, reinforcing differentiation of neo-X and neo-Y and revealing the occurrence of multiple additional rearrangements involved in the neo-Y evolution of R. bergii. We discussed the possible causes that led to differences in frequency for the neo-Y variants between embryos and adults. Finally we hypothesize about the role of DNA satellites in R. bergii as well as putative historical events involved in the evolution of the R. bergii neo-XY.

  20. Working Late: Do Workplace Sex Ratios Affect Partnership Formation and Dissolution?

    Science.gov (United States)

    Svarer, Michael

    2007-01-01

    In this paper, I analyze the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios are not important for the overall transition rate from…

  1. Sex ratios in the two Germanies: a test of the economic stress hypothesis.

    Science.gov (United States)

    Catalano, Ralph A

    2003-09-01

    Literature describing temporal variation in the secondary sex ratio among humans reports an association between population stressors and declines in the odds of male birth. Explanations of this phenomenon draw on reports that stressed females spontaneously abort male more than female fetuses, and that stressed males exhibit reduced sperm motility. This work has led to the argument that population stress induced by a declining economy reduces the human sex ratio. No direct test of this hypothesis appears in the literature. Here, a test is offered based on a comparison of the sex ratio in East and West Germany for the years 1946 to 1999. The theory suggests that the East German sex ratio should be lower in 1991, when East Germany's economy collapsed, than expected from its own history and from the sex ratio in West Germany. The hypothesis is tested using time-series modelling methods. The data support the hypothesis. The sex ratio in East Germany was at its lowest in 1991. This first direct test supports the hypothesis that economic decline reduces the human sex ratio.

  2. Going All In: Unfavorable Sex Ratios Attenuate Choice Diversification.

    Science.gov (United States)

    Ackerman, Joshua M; Maner, Jon K; Carpenter, Stephanie M

    2016-06-01

    When faced with risky decisions, people typically choose to diversify their choices by allocating resources across a variety of options and thus avoid putting "all their eggs in one basket." The current research revealed that this tendency is reversed when people face an important cue to mating-related risk: skew in the operational sex ratio, or the ratio of men to women in the local environment. Counter to the typical strategy of choice diversification, findings from four studies demonstrated that the presence of romantically unfavorable sex ratios (those featuring more same-sex than opposite-sex individuals) led heterosexual people to diversify financial resources less and instead concentrate investment in high-risk/high-return options when making lottery, stock-pool, retirement-account, and research-funding decisions. These studies shed light on a key process by which people manage risks to mating success implied by unfavorable interpersonal environments. These choice patterns have important implications for mating behavior as well as other everyday forms of decision making. © The Author(s) 2016.

  3. Association of secondary sex ratio with smoking and parity.

    Science.gov (United States)

    Beratis, Nicholas G; Asimacopoulou, Aspasia; Varvarigou, Anastasia

    2008-03-01

    To assess the sex ratio in offspring of smoking and nonsmoking mothers in relationship to parity. Prospective study. University hospital. The authors studied 2,108 term singleton neonates born between 1993 and 2002, 665 from smoking mothers and 1,443 from nonsmoking mothers. A prospective recording of maternal age, parity and smoking status, and gender of neonates delivered over a 10-year period. Secondary sex ratio in regard to maternal smoking and parity. The offspring sex ratio in the total sample studied was 1.09; in the offspring of smoking and nonsmoking mothers, it was 1.26 and 1.03, respectively, a statistically significant difference. In the offspring of smoking women who had parity 1, 2, and >or=3, it was 1.47, 1.35, and 0.92, whereas in those of nonsmoking women, it was 1.04, 1.00, and 1.03, respectively (the differences of the parity 1 and 2 groups between the offspring of smoking and nonsmoking mothers were statistically significant). Logistic regression analysis showed that the possibility of a boy being delivered by a mother who smoked was significantly greater in primiparous women than in women who had parity >or=3, independent of the maternal age. Conversely, parity did not affect significantly the sex ratio in the offspring of nonsmoking women. The findings suggest that among women who smoked, significantly more male than female offspring are born from primiparous women, whereas women who had parity >or=3 gave birth to more female offspring; biparous women give birth to significantly more male offspring, but the offspring sex ratio declined with the number of cigarettes when the mothers smoked >or=10 cigarettes per day.

  4. Adult sex ratio variation: implications for breeding system evolution.

    Science.gov (United States)

    Székely, T; Weissing, F J; Komdeur, J

    2014-08-01

    Adult sex ratio (ASR) exhibits immense variation in nature, although neither the causes nor the implications of this variation are fully understood. According to theory, the ASR is expected to influence sex roles and breeding systems, as the rarer sex in the population has more potential partners to mate with than the more common sex. Changes in mate choice, mating systems and parental care suggest that the ASR does influence breeding behaviour, although there is a need for more tests, especially experimental ones. In the context of breeding system evolution, the focus is currently on operational sex ratios (OSRs). We argue that the ASR plays a role of similar importance and urge researchers to study the ASR and the OSR side by side. Finally, we plead for a dynamic view of breeding system evolution with feedbacks between mating, parenting, OSR and ASR on both ecological and evolutionary time scales. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  5. The impact of sex ratio and economic status on local birth rates

    OpenAIRE

    Chipman, A.; Morrison, E.

    2013-01-01

    Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated w...

  6. Invited commentary: Natural versus unnatural sex ratios--a quandary of modern times.

    Science.gov (United States)

    Wilcox, Allen J; Baird, Donna D

    2011-12-15

    The typical dilemma with sex-ratio findings is that when they are real, they aren't interesting, and when they are interesting, they aren't real. In this issue of the Journal, Fernández et al. (Am J Epidemiol. 2011;174(12):1327-1331) describe a deviation of the sex ratio that is apparently both large and real. There was a temporary but distinct spike in the proportion of boys born in Cuba around the time of the collapse of the national economy during the 1990s. Although an excess of boys does not fit the prevailing biologic theory regarding maternal stress and the sex ratio, the data are consistent with results from the Dutch famine (where population-level deprivation was even more extreme). A new quandary arises in the modern era with interpretation of the sex ratio: If the decision to abort a pregnancy is influenced by the sex of the fetus, a change in the behavior of even a small proportion of women could influence the sex ratio at birth. The possible role of sex selection in the Cuban context is discussed.

  7. Adult sex ratios and their implications for cooperative breeding in birds.

    Science.gov (United States)

    Komdeur, Jan; Székely, Tamás; Long, Xiaoyan; Kingma, Sjouke A

    2017-09-19

    Cooperative breeding is a form of breeding system where in addition to a core breeding pair, one or more usually non-breeding individuals provide offspring care. Cooperative breeding is widespread in birds, but its origin and maintenance in contemporary populations are debated. Although deviations in adult sex ratio (ASR, the proportion of males in the adult population) have been hypothesized to influence the occurrence of cooperative breeding because of the resulting surplus of one sex and limited availability of breeding partners, this hypothesis has not been tested across a wide range of taxa. By using data from 188 bird species and phylogenetically controlled analyses, we show that cooperatively breeding species have more male-biased ASRs than non-cooperative species. Importantly, ASR predicts helper sex ratio: in species with more male-biased ASR, helper sex ratio is also more male biased. We also show that offspring sex ratios do not predict ASRs, so that the skewed ASRs emerge during the period when individuals aim to obtain a breeding position or later during adulthood. In line with this result, we found that ASR (among both cooperatively and non-cooperatively breeding species) is inversely related to sex bias in dispersal distance, suggesting that the cost of dispersal is more severe for the further-dispersing sex. As females usually disperse further in birds, this explains the generally male-biased ASR, and in combination with benefits of philopatry for males, this probably explains why ASR is more biased in cooperatively breeding species. Taken together, our results suggest that a sex bias in helping in cooperatively breeding species relates to biased ASRs. We propose that this relationship is driven by sex-specific costs and benefits of dispersal and helping, as well as other demographic factors. Future phylogenetic comparative and experimental work is needed to establish how this relationship emerges.This article is part of the themed issue 'Adult sex

  8. India's Distorted Sex Ratio: Dire Consequences for Girls.

    Science.gov (United States)

    Roberts, Lisa R; Montgomery, Susanne B

    2016-01-01

    Female gender discrimination related to cultural preference for males is a common global problem, especially in Asian countries. Numerous laws intended to prevent discrimination on the basis of gender have been passed in India, yet the distorted female-to-male sex ratio seems to show worsening tendencies. Using detailed, two-year longitudinal chart abstraction data about delivery records of a private mission hospital in rural India, we explored if hospital birth ratio data differed in comparison to regional data, and what demographic and contextual variables may have influenced these outcomes. Using quantitative chart abstraction and qualitative contextual data, study results showed the female-to-male ratio was lower than the reported state ratio at birth. In the context of India's patriarchal structure, with its strong son preference, women are under tremendous pressure or coerced to access community-based, sex-selective identification and female fetus abortion. Nurses may be key to turning the tide.

  9. Semi-automatic laser beam microdissection of the Y chromosome and analysis of Y chromosome DNA in a dioecious plant, Silene latifolia

    International Nuclear Information System (INIS)

    Matsunaga, S.; Kawano, S.; Michimoto, T.; Higashiyama, T.; Nakao, S.; Sakai, A.; Kuroiwa, T.

    1999-01-01

    Silene latifolia has heteromorphic sex chromosomes, the X and Y chromosomes. The Y chromosome, which is thought to carry the male determining gene, was isolated by UV laser microdissection and amplified by degenerate oligonucleotide-primed PCR. In situ chromosome suppression of the amplified Y chromosome DNA in the presence of female genomic DNA as a competitor showed that the microdissected Y chromosome DNA did not specifically hybridize to the Y chromosome, but-hybridized to all chromosomes. This result suggests that the Y chromosome does not contain Y chromosome-enriched repetitive sequences. A repetitive sequence in the microdissected Y chromosome, RMY1, was isolated while screening repetitive sequences in the amplified Y chromosome. Part of the nucleotide sequence shared a similarity to that of X-43.1, which was isolated from microdissected X chromosomes. Since fluorescence in situ hybridization analysis with RMY1 demonstrated that RMY1 was localized at the ends of the chromosome, RMY1 may be a subtelomeric repetitive sequence. Regarding the sex chromosomes, RMY1 was detected at both ends of the X chromosome and at one end near the pseudoautosomal region of the Y chromosome. The different localization of RMY1 on the sex chromosomes provides a clue to the problem of how the sex chromosomes arose from autosomes

  10. Sex-linked dominant

    Science.gov (United States)

    Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant ... can be either an autosomal chromosome or a sex chromosome. It also depends on whether the trait ...

  11. Sex Ratio Bias Leads to the Evolution of Sex Role Reversal in Honey Locust Beetles.

    Science.gov (United States)

    Fritzsche, Karoline; Booksmythe, Isobel; Arnqvist, Göran

    2016-09-26

    The reversal of conventional sex roles was enigmatic to Darwin, who suggested that it may evolve when sex ratios are female biased [1]. Here we present direct evidence confirming Darwin's hypothesis. We investigated mating system evolution in a sex-role-reversed beetle (Megabruchidius dorsalis) using experimental evolution under manipulated sex ratios and food regimes. In female-biased populations, where reproductive competition among females was intensified, females evolved to be more attractive and the sex roles became more reversed. Interestingly, female-specific mating behavior evolved more rapidly than male-specific mating behavior. We show that sexual selection due to reproductive competition can be strong in females and can target much the same traits as in males of species with conventional mating systems. Our study highlights two central points: the role of ecology in directing sexual selection and the role that females play in mating system evolution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Nuclear organization in human sperm: preliminary evidence for altered sex chromosome centromere position in infertile males.

    Science.gov (United States)

    Finch, K A; Fonseka, K G L; Abogrein, A; Ioannou, D; Handyside, A H; Thornhill, A R; Hickson, N; Griffin, D K

    2008-06-01

    Many genetic defects with a chromosomal basis affect male reproduction via a range of different mechanisms. Chromosome position is a well-known marker of nuclear organization, and alterations in standard patterns can lead to disease phenotypes such as cancer, laminopathies and epilepsy. It has been demonstrated that normal mammalian sperm adopt a pattern with the centromeres aligning towards the nuclear centre. The purpose of this study was to test the hypothesis that altered chromosome position in the sperm head is associated with male infertility. The average nuclear positions of fluorescence in-situ hybridization signals for three centromeric probes (for chromosomes X, Y and 18) were compared in normoozoospermic men and in men with compromised semen parameters. In controls, the centromeres of chromosomes X, Y and 18 all occupied a central nuclear location. In infertile men the sex chromosomes appeared more likely to be distributed in a pattern not distinguishable from a random model. Our findings cast doubt on the reliability of centromeric probes for aneuploidy screening. The analysis of chromosome position in sperm heads should be further investigated for the screening of infertile men.

  13. Abnormal sex ratios in human populations: causes and consequences.

    Science.gov (United States)

    Hesketh, Therese; Xing, Zhu Wei

    2006-09-05

    In the absence of manipulation, both the sex ratio at birth and the population sex ratio are remarkably constant in human populations. Small alterations do occur naturally; for example, a small excess of male births has been reported to occur during and after war. The tradition of son preference, however, has distorted these natural sex ratios in large parts of Asia and North Africa. This son preference is manifest in sex-selective abortion and in discrimination in care practices for girls, both of which lead to higher female mortality. Differential gender mortality has been a documented problem for decades and led to reports in the early 1990s of 100 million "missing women" across the developing world. Since that time, improved health care and conditions for women have resulted in reductions in female mortality, but these advances have now been offset by a huge increase in the use of sex-selective abortion, which became available in the mid-1980s. Largely as a result of this practice, there are now an estimated 80 million missing females in India and China alone. The large cohorts of "surplus" males now reaching adulthood are predominantly of low socioeconomic class, and concerns have been expressed that their lack of marriageability, and consequent marginalization in society, may lead to antisocial behavior and violence, threatening societal stability and security. Measures to reduce sex selection must include strict enforcement of existing legislation, the ensuring of equal rights for women, and public awareness campaigns about the dangers of gender imbalance.

  14. Persistent sex-by-environment effects on offspring fitness and sex-ratio adjustment in a wild bird population.

    Science.gov (United States)

    Bowers, E Keith; Thompson, Charles F; Sakaluk, Scott K

    2015-03-01

    A major component of sex-allocation theory, the Trivers-Willard model (TWM), posits that sons and daughters are differentially affected by variation in the rearing environment. In many species, the amount of parental care received is expected to have differing effects on the fitness of males and females. When this occurs, the TWM predicts that selection should favour adjustment of the offspring sex ratio in relation to the expected fitness return from offspring. However, evidence for sex-by-environment effects is mixed, and little is known about the adaptive significance of producing either sex. Here, we test whether offspring sex ratios vary according to predictions of the TWM in the house wren (Troglodytes aedon, Vieillot). We also test the assumption of a sex-by-environment effect on offspring using two experiments, one in which we manipulated age differences among nestlings within broods, and another in which we held nestling age constant but manipulated brood size. As predicted, females with high investment ability overproduced sons relative to those with lower ability. Males were also overproduced early within breeding seasons. In our experiments, the body mass of sons was more strongly affected by the sibling-competitive environment and resource availability than that of daughters: males grew heavier than females when reared in good conditions but were lighter than females when in poor conditions. Parents rearing broods with 1:1 sex ratios were more productive than parents rearing broods biased more strongly towards sons or daughters, suggesting that selection favours the production of mixed-sex broods. However, differences in the condition of offspring as neonates persisted to adulthood, and their reproductive success as adults varied with the body mass of sons, but not daughters, prior to independence from parental care. Thus, selection should favour slight but predictable variations in the sex ratio in relation to the quality of offspring that parents are

  15. The financial consequences of too many men: sex ratio effects on saving, borrowing, and spending.

    Science.gov (United States)

    Griskevicius, Vladas; Tybur, Joshua M; Ackerman, Joshua M; Delton, Andrew W; Robertson, Theresa E; White, Andrew E

    2012-01-01

    The ratio of males to females in a population is an important factor in determining behavior in animals. We propose that sex ratio also has pervasive effects in humans, such as by influencing economic decisions. Using both historical data and experiments, we examined how sex ratio influences saving, borrowing, and spending in the United States. Findings show that male-biased sex ratios (an abundance of men) lead men to discount the future and desire immediate rewards. Male-biased sex ratios decreased men's desire to save for the future and increased their willingness to incur debt for immediate expenditures. Sex ratio appears to influence behavior by increasing the intensity of same-sex competition for mates. Accordingly, a scarcity of women led people to expect men to spend more money during courtship, such as by paying more for engagement rings. These findings demonstrate experimentally that sex ratio influences human decision making in ways consistent with evolutionary biological theory. Implications for sex ratio effects across cultures are discussed.

  16. The evolution of sex roles in birds is related to adult sex ratio.

    Science.gov (United States)

    Liker, András; Freckleton, Robert P; Székely, Tamás

    2013-01-01

    Sex-role reversal represents a formidable challenge for evolutionary biologists, since it is not clear which ecological, life-history or social factors facilitated conventional sex roles (female care and male-male competition for mates) to be reversed (male care and female-female competition). Classic theories suggested ecological or life-history predictors of role reversal, but most studies failed to support these hypotheses. Recent theory however predicts that sex-role reversal should be driven by male-biased adult sex ratio (ASR). Here we test this prediction for the first time using phylogenetic comparative analyses. Consistent with theory, both mating system and parental care are strongly related to ASR in shorebirds: conventional sex roles are exhibited by species with female-biased ASR, whereas sex-role reversal is associated with male-biased ASR. These results suggest that social environment has a strong influence on breeding systems and therefore revealing the causes of ASR variation in wild populations is essential for understanding sex role evolution.

  17. Maternal condition but not corticosterone is linked to offspring sex ratio in a passerine bird.

    Directory of Open Access Journals (Sweden)

    Lindsay J Henderson

    Full Text Available There is evidence of offspring sex ratio adjustment in a range of species, but the potential mechanisms remain largely unknown. Elevated maternal corticosterone (CORT is associated with factors that can favour brood sex ratio adjustment, such as reduced maternal condition, food availability and partner attractiveness. Therefore, the steroid hormone has been suggested to play a key role in sex ratio manipulation. However, despite correlative and causal evidence CORT is linked to sex ratio manipulation in some avian species, the timing of adjustment varies between studies. Consequently, whether CORT is consistently involved in sex-ratio adjustment, and how the hormone acts as a mechanism for this adjustment remains unclear. Here we measured maternal baseline CORT and body condition in free-living blue tits (Cyanistes caeruleus over three years and related these factors to brood sex ratio and nestling quality. In addition, a non-invasive technique was employed to experimentally elevate maternal CORT during egg laying, and its effects upon sex ratio and nestling quality were measured. We found that maternal CORT was not correlated with brood sex ratio, but mothers with elevated CORT fledged lighter offspring. Also, experimental elevation of maternal CORT did not influence brood sex ratio or nestling quality. In one year, mothers in superior body condition produced male biased broods, and maternal condition was positively correlated with both nestling mass and growth rate in all years. Unlike previous studies maternal condition was not correlated with maternal CORT. This study provides evidence that maternal condition is linked to brood sex ratio manipulation in blue tits. However, maternal baseline CORT may not be the mechanistic link between the maternal condition and sex ratio adjustment. Overall, this study serves to highlight the complexity of sex ratio adjustment in birds and the difficulties associated with identifying sex biasing mechanisms.

  18. Analysis of the Ceratitis capitata y chromosome using in situ hybridization to mitotic chromosomes

    International Nuclear Information System (INIS)

    Willhoeft, U.; Franz, G.

    1998-01-01

    In Ceratitis capitata the Y chromosome is responsible for sex-determination. We used fluorescence in situ hybridization (FISH) for cytogenetic analysis of mitotic chromosomes. FISH with the wild-type strain EgyptII and two repetitive DNA probes enabled us to differentiate between the short and the long arm of the Y chromosome and gives a much better resolution than C-banding of mitotic chromosomes. We identified the Y-chromosomal breakpoints in Y-autosome translocations using FISH. Even more complex rearrangements i.e. deletions and insertions in some translocation strains were detected by this method. A strategy for mapping the primary sex determination factor in Ceratitis capitata by FISH is presented. (author)

  19. Paternal effects on the human sex ratio at birth: evidence from interracial crosses.

    Science.gov (United States)

    Khoury, M J; Erickson, J D; James, L M

    1984-01-01

    The effects of interracial crossing on the human sex ratio at birth were investigated using United States birth-certificate data for 1972-1979. The sex ratio was 1.059 for approximately 14 million singleton infants born to white couples, 1.033 for 2 million born to black couples, and 1.024 for 64,000 born to American Indian couples. Paternal and maternal race influences on the observed racial differences in sex ratio were analyzed using additional data on approximately 97,000 singleton infants born to white-black couples and 60,000 born to white-Indian couples. After adjustment for mother's race, white fathers had significantly more male offspring than did black fathers (ratio of sex ratios [RSR] = 1.027) and Indian fathers (RSR = 1.022). On the other hand, after adjustment for father's race, white mothers did not have more male offspring than did black mothers (RSR = 0.998) or Indian mothers (RSR = 1.009). The paternal-race effect persisted after adjustment for parental ages, education, birth order, and maternal marital status. The study shows that the observed racial differences in the sex ratio at birth are due to the effects of father's race and not the mother's. The study points to paternal determinants of the human sex ratio at fertilization and/or of the prenatal differential sex survival. PMID:6496474

  20. Sex-Specific Arrival Times on the Breeding Grounds: Hybridizing Migratory Skuas Provide Empirical Support for the Role of Sex Ratios.

    Science.gov (United States)

    Lisovski, Simeon; Fröhlich, Anne; von Tersch, Matthew; Klaassen, Marcel; Peter, Hans-Ulrich; Ritz, Markus S

    2016-04-01

    In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio.

  1. National, regional, and global sex ratios of infant, child, and under-5 mortality and identification of countries with outlying ratios: a systematic assessment.

    Science.gov (United States)

    Alkema, Leontine; Chao, Fengqing; You, Danzhen; Pedersen, Jon; Sawyer, Cheryl C

    2014-09-01

    Under natural circumstances, the sex ratio of male to female mortality up to the age of 5 years is greater than one but sex discrimination can change sex ratios. The estimation of mortality by sex and identification of countries with outlying levels is challenging because of issues with data availability and quality, and because sex ratios might vary naturally based on differences in mortality levels and associated cause of death distributions. For this systematic analysis, we estimated country-specific mortality sex ratios for infants, children aged 1-4 years, and children under the age of 5 years (under 5s) for all countries from 1990 (or the earliest year of data collection) to 2012 using a Bayesian hierarchical time series model, accounting for various data quality issues and assessing the uncertainty in sex ratios. We simultaneously estimated the global relation between sex ratios and mortality levels and constructed estimates of expected and excess female mortality rates to identify countries with outlying sex ratios. Global sex ratios in 2012 were 1·13 (90% uncertainty interval 1·12-1·15) for infants, 0·95 (0·93-0·97) for children aged 1-5 years, and 1·08 (1·07-1·09) for under 5s, an increase since 1990 of 0·01 (-0·01 to 0·02) for infants, 0·04 (0·02 to 0·06) for children aged 1-4 years, and 0·02 (0·01 to 0·04) for under 5s. Levels and trends varied across regions and countries. Sex ratios were lowest in southern Asia for 1990 and 2012 for all age groups. Highest sex ratios were seen in developed regions and the Caucasus and central Asia region. Decreasing mortality was associated with increasing sex ratios, except at very low infant mortality, where sex ratios decreased with total mortality. For 2012, we identified 15 countries with outlying under-5 sex ratios, of which ten countries had female mortality higher than expected (Afghanistan, Bahrain, Bangladesh, China, Egypt, India, Iran, Jordan, Nepal, and Pakistan). Although excess female

  2. Territory Quality and Plumage Morph Predict Offspring Sex Ratio Variation in a Raptor.

    Directory of Open Access Journals (Sweden)

    Nayden Chakarov

    Full Text Available Parents may adapt their offspring sex ratio in response to their own phenotype and environmental conditions. The most significant causes for adaptive sex-ratio variation might express themselves as different distributions of fitness components between sexes along a given variable. Several causes for differential sex allocation in raptors with reversed sexual size dimorphism have been suggested. We search for correlates of fledgling sex in an extensive dataset on common buzzards Buteo buteo, a long-lived bird of prey. Larger female offspring could be more resource-demanding and starvation-prone and thus the costly sex. Prominent factors such as brood size and laying date did not predict nestling sex. Nonetheless, lifetime sex ratio (LSR, potentially indicative of individual sex allocation constraints and overall nestling sex were explained by territory quality with more females being produced in better territories. Additionally, parental plumage morphs and the interaction of morph and prey abundance tended to explain LSR and nestling sex, indicating local adaptation of sex allocation However, in a limited census of nestling mortality, not females but males tended to die more frequently in prey-rich years. Also, although females could have potentially longer reproductive careers, a subset of our data encompassing full individual life histories showed that longevity and lifetime reproductive success were similarly distributed between the sexes. Thus, a basis for adaptive sex allocation in this population remains elusive. Overall, in common buzzards most major determinants of reproductive success appeared to have no effect on sex ratio but sex allocation may be adapted to local conditions in morph-specific patterns.

  3. Statistics for X-chromosome associations.

    Science.gov (United States)

    Özbek, Umut; Lin, Hui-Min; Lin, Yan; Weeks, Daniel E; Chen, Wei; Shaffer, John R; Purcell, Shaun M; Feingold, Eleanor

    2018-06-13

    In a genome-wide association study (GWAS), association between genotype and phenotype at autosomal loci is generally tested by regression models. However, X-chromosome data are often excluded from published analyses of autosomes because of the difference between males and females in number of X chromosomes. Failure to analyze X-chromosome data at all is obviously less than ideal, and can lead to missed discoveries. Even when X-chromosome data are included, they are often analyzed with suboptimal statistics. Several mathematically sensible statistics for X-chromosome association have been proposed. The optimality of these statistics, however, is based on very specific simple genetic models. In addition, while previous simulation studies of these statistics have been informative, they have focused on single-marker tests and have not considered the types of error that occur even under the null hypothesis when the entire X chromosome is scanned. In this study, we comprehensively tested several X-chromosome association statistics using simulation studies that include the entire chromosome. We also considered a wide range of trait models for sex differences and phenotypic effects of X inactivation. We found that models that do not incorporate a sex effect can have large type I error in some cases. We also found that many of the best statistics perform well even when there are modest deviations, such as trait variance differences between the sexes or small sex differences in allele frequencies, from assumptions. © 2018 WILEY PERIODICALS, INC.

  4. The male handicap: male-biased mortality explains skewed sex ratios in brown trout embryos.

    Science.gov (United States)

    Morán, P; Labbé, L; Garcia de Leaniz, C

    2016-12-01

    Juvenile sex ratios are often assumed to be equal for many species with genetic sex determination, but this has rarely been tested in fish embryos due to their small size and absence of sex-specific markers. We artificially crossed three populations of brown trout and used a recently developed genetic marker for sexing the offspring of both pure and hybrid crosses. Sex ratios (SR = proportion of males) varied widely one month after hatching ranging from 0.15 to 0.90 (mean = 0.39 ± 0.03). Families with high survival tended to produce balanced or male-biased sex ratios, but SR was significantly female-biased when survival was low, suggesting that males sustain higher mortality during development. No difference in SR was found between pure and hybrid families, but the existence of sire × dam interactions suggests that genetic incompatibility may play a role in determining sex ratios. Our findings have implications for animal breeding and conservation because skewed sex ratios will tend to reduce effective population size and bias selection estimates. © 2016 The Authors.

  5. Effects of chromosomal sex and hormonal influences on shaping sex differences in brain and behavior: Lessons from cases of disorders of sex development.

    Science.gov (United States)

    Bramble, Matthew S; Lipson, Allen; Vashist, Neerja; Vilain, Eric

    2017-01-02

    Sex differences in brain development and postnatal behavior are determined largely by genetic sex and in utero gonadal hormone secretions. In humans however, determining the weight that each of these factors contributes remains a challenge because social influences should also be considered. Cases of disorders of sex development (DSD) provide unique insight into how mutations in genes responsible for gonadal formation can perturb the subsequent developmental hormonal milieu and elicit changes in normal human brain maturation. Specific forms of DSDs such as complete androgen insensitivity syndrome (CAIS), congenital adrenal hyperplasia (CAH), and 5α-reductase deficiency syndrome have variable effects between males and females, and the developmental outcomes of such conditions are largely dependent on sex chromosome composition. Medical and psychological works focused on CAH, CAIS, and 5α-reductase deficiency have helped form the foundation for understanding the roles of genetic and hormonal factors necessary for guiding human brain development. Here we highlight how the three aforementioned DSDs contribute to brain and behavioral phenotypes that can uniquely affect 46,XY and 46,XX individuals in dramatically different fashions. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Meiotic sex chromosome inactivation is disrupted in sterile hybrid male house mice.

    Science.gov (United States)

    Campbell, Polly; Good, Jeffrey M; Nachman, Michael W

    2013-03-01

    In male mammals, the X and Y chromosomes are transcriptionally silenced in primary spermatocytes by meiotic sex chromosome inactivation (MSCI) and remain repressed for the duration of spermatogenesis. Here, we test the longstanding hypothesis that disrupted MSCI might contribute to the preferential sterility of heterogametic hybrid males. We studied a cross between wild-derived inbred strains of Mus musculus musculus and M. m. domesticus in which sterility is asymmetric: F1 males with a M. m. musculus mother are sterile or nearly so while F1 males with a M. m. domesticus mother are normal. In previous work, we discovered widespread overexpression of X-linked genes in the testes of sterile but not fertile F1 males. Here, we ask whether this overexpression is specifically a result of disrupted MSCI. To do this, we isolated cells from different stages of spermatogenesis and measured the expression of several genes using quantitative PCR. We found that X overexpression in sterile F1 primary spermatocytes is coincident with the onset of MSCI and persists in postmeiotic spermatids. Using a series of recombinant X genotypes, we then asked whether X overexpression in hybrids is controlled by cis-acting loci across the X chromosome. We found that it is not. Instead, one large interval in the proximal portion of the M. m. musculus X chromosome is associated with both overexpression and the severity of sterility phenotypes in hybrids. These results demonstrate a strong association between X-linked hybrid male sterility and disruption of MSCI and suggest that trans-acting loci on the X are important for the transcriptional regulation of the X chromosome during spermatogenesis.

  7. Different sex ratios of children born to Indian and Pakistani immigrants in Norway

    Directory of Open Access Journals (Sweden)

    Brekke Torkel

    2010-08-01

    Full Text Available Abstract Background A low female-to-male ratio has been observed in different Asian countries, but this phenomenon has not been well studied among immigrants living in Western societies. In this study, we investigated whether a low female-to-male ratio exists among Indian and Pakistani immigrants living in Norway. In particular, we investigated whether the determination of sex via ultrasound examination, a common obstetric procedure that has been used in Norway since the early 1980 s, has influenced the female-to-male ratio among children born to parents of Indian or Pakistani origin. Methods We performed a retrospective cohort study of live births in mothers of Indian (n = 1597 and Pakistani (n = 5617 origin. Data were obtained from "Statistics Norway" and the female-to-male (F/M sex ratio was evaluated among 21,325 children born, in increasing birth order, during three stratified periods (i.e., 1969-1986, 1987-1996, and 1997-2005. Results A significant low female-to-male sex ratio was observed among children in the third and fourth birth order (sex ratio 65; 95% CI 51-80 from mothers of Indian origin who gave birth after 1987. Sex ratios did not deviate from the expected natural variation in the Indian cohort from 1969 to 1986, and remained stable in the Pakistani cohort during the entire study period. However, the female-to-male sex ratio seemed less skewed in recent years (i.e., 1997-2005. Conclusion Significant differences were observed in the sex ratio of children born to mothers of Indian origin compared with children born to mothers of Pakistani origin. A skewed number of female births among higher birth orders (i.e., third or later may partly reflect an increase in sex-selective abortion among mothers of Indian origin, although the numbers are too small to draw firm conclusions. Further research is needed to explain the observed differences in the female-to-male ratio among members of these ethnic groups who reside in Norway.

  8. The sex ratio distortion in the human head louse is conserved over time

    Directory of Open Access Journals (Sweden)

    Biliński Szczepan M

    2004-05-01

    Full Text Available Abstract Background At the turn of the 19th century the first observations of a female-biased sex ratio in broods and populations of the head louse, Pediculus humanus capitis, had been reported. A study by Buxton in 1940 on the sex ratio of lice on prisoners in Ceylon is still today the subject of reanalyses. This sex ratio distortion had been detected in ten different countries. In the last sixty years no new data have been collected, especially on scalp infestations under economically and socially more developed conditions. Results Here we report a female bias of head lice in a survey of 480 school children in Argentina. This bias is independent of the intensity of the pediculosis, which makes local mate competition highly unlikely as the source of the aberrant sex ratio; however, other possible adaptive mechanisms cannot be discounted. These lice as well as lice from pupils in Britain were carrying several strains of the endosymbiotic bacterium Wolbachia pipientis, one of the most wide spread intracellular sex ratio distorters. Similar Wolbachia strains are also present in the pig louse, Haematopinus suis, suggesting that this endosymbiont might have a marked influence on the biology of the whole order. The presence of a related obligate nutritional bacterium in lice prevents the investigation of a causal link between sex ratio and endosymbionts. Conclusions Regardless of its origin, this sex ratio distortion in head lice that has been reported world wide, is stable over time and is a remarkable deviation from the stability of frequency-dependent selection of Fisher's sex ratio. A female bias first reported in 1898 is still present over a hundred years and a thousand generations later.

  9. Manipulation of primary sex ratio in birds: lessons from the homing pigeon (Columba livia domestica).

    Science.gov (United States)

    Goerlich-Jansson, Vivian C; Müller, Martina S; Groothuis, Ton G G

    2013-12-01

    Across various animal taxa not only the secondary sex ratio but also the primary sex ratio (at conception) shows significant deviations from the expected equal proportions of sons and daughters. Birds are especially intriguing to study this phenomenon as avian females are the heterogametic sex (ZW); therefore sex determination might be under direct control of the mother. Avian sex ratios vary in relation to environmental or maternal condition, which can also affect the production of maternal steroids that in turn are involved in reproduction and accumulate in the developing follicle before meiosis. As the proximate mechanisms underlying biased primary sex ratio are largely elusive, we explored how, and to what extent, maternal steroid hormones may be involved in affecting primary or secondary sex ratio in clutches of various species of pigeons. First we demonstrated a clear case of seasonal change in sex ratio in first eggs both in the Rock Pigeon (Columba livia) and in a related species, the Wood Pigeon (Columba palumbus), both producing clutches of two eggs. In the Homing Pigeon (Columba livia domestica), domesticated from the Rock Pigeon, testosterone treatment of breeding females induced a clear male bias, while corticosterone induced a female bias in first eggs and we argue that this is in line with sex allocation theory. We next analyzed treatment effects on follicle formation, yolk mass, and yolk hormones, the latter both pre- and post-ovulatory, in order to test a diversity of potential mechanisms related to both primary and secondary sex ratio manipulation. We conclude that maternal plasma hormone levels may affect several pre-ovulatory mechanisms affecting primary sex ratio, whereas egg hormones are probably involved in secondary sex ratio manipulation only.

  10. Mother's prior intrauterine position affects the sex ratio of her offspring in house mice.

    Science.gov (United States)

    Vandenbergh, J G; Huggett, C L

    1994-11-08

    Sex ratio alterations related to environmental factors occur in several mammals, but no mechanism has been identified to explain the adjustment. Intrauterine position (IUP) may provide the context in which such alterations occur. Previous studies on house mice and gerbils reveal that the position of a fetus in the uterus in relation to the sex of its neighbors influences its later anatomy, physiology, and behavior. The anogenital distance (AGD) of females located between two males (2M) is longer than that of females not between two males (OM). We have found that the IUP, as determined by cesarean section and by an index of the AGD, correlates with the sex ratio of the litters produced by female mice. The sex ratio of the first litter born to 2M females was 58% males, for 1M females was 51% males and for OM females was 42% males. The effect on sex ratio continues into the second litter. The number of pups produced by mothers of different IUPs in her first two litters did not differ, suggesting that the sex ratio adjustment occurs prior to parturition. These results provide a basis for the natural variability observed in sex ratios of litter-bearing mammals and suggest that one or more intrauterine mechanisms may be responsible for environmentally related sex ratio alterations.

  11. Does predation control adult sex ratios and longevities in marine pelagic copepods?

    DEFF Research Database (Denmark)

    Hirst, A.G.; Bonnet, D.; Conway, D.V.P.

    2010-01-01

    We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late...... copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes...... in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona...

  12. Differentiation of sex chromosomes and karyotypic evolution in the eye-lid geckos (Squamata: Gekkota: Eublepharidae), a group with different modes of sex determination

    Czech Academy of Sciences Publication Activity Database

    Pokorná, M.; Rábová, Marie; Ráb, Petr; Kratochvíl, L.

    2010-01-01

    Roč. 18, č. 6 (2010), s. 748-748 ISSN 0967-3849. [19th International Colloquium on animal cytogenetics and gene mapping. 06.06.-09.06.2010, Krakow] Institutional research plan: CEZ:AV0Z50450515 Keywords : sex chromosomes * karyotypic evolution * eye-lid geckos Subject RIV: EB - Genetics ; Molecular Biology

  13. National, regional, and global sex ratios of infant, child, and under-5 mortality and identification of countries with outlying ratios: a systematic assessment

    OpenAIRE

    Alkema, Leontine; Chao, Fengqing; You, Danzhen; Pedersen, Jon; Sawyer, Cheryl C

    2014-01-01

    Background: Under natural circumstances, the sex ratio of male to female mortality up to the age of 5 years is greater than one but sex discrimination can change sex ratios. The estimation of mortality by sex and identification of countries with outlying levels is challenging because of issues with data availability and quality, and because sex ratios might vary naturally based on differences in mortality levels and associated cause of death distributions. Methods: For this systematic anal...

  14. Sex ratio at birth and mortality rates are negatively related in humans.

    Directory of Open Access Journals (Sweden)

    Madhukar Shivajirao Dama

    Full Text Available Evolutionary theory posits that resource availability and parental investment ability could signal offspring sex selection, in order to maximize reproductive returns. Non-human studies have provided evidence for this phenomenon, and maternal condition around the time of conception has been identified as most important factor that influence offspring sex selection. However, studies on humans have reported inconsistent results, mostly due to use of disparate measures as indicators of maternal condition. In the present study, the cross-cultural differences in human natal sex ratio were analyzed with respect to indirect measures of condition namely, life expectancy and mortality rate. Multiple regression modeling suggested that mortality rates have distinct predictive power independent of cross-cultural differences in fertility, wealth and latitude that were earlier shown to predict sex ratio at birth. These findings suggest that sex ratio variation in humans may relate to differences in parental and environmental conditions.

  15. Gender Inequality and the Sex Ratio in Three Emerging Economies

    OpenAIRE

    Prabir C. Bhattacharya

    2012-01-01

    The aim of this paper is to study inequality and deprivations as reflected in the human sex ratio (commonly defined as the number of males per 100 females). The particular focus is on three emerging economies, viz., Russia, India and China. The paper compares and contrasts the experiences of these countries and discusses policy issues. It is noted that while the feminist perspective on the issues surrounding the sex ratio is important, it would be wrong to view these issues always or exclusiv...

  16. India’s Distorted Sex Ratio: Dire Consequences for Girls

    Science.gov (United States)

    Roberts, Lisa R.; Montgomery, Susanne B.

    2017-01-01

    Female gender discrimination related to cultural preference for males is a common global problem, especially in Asian countries. Numerous laws intended to prevent discrimination on the basis of gender have been passed in India, yet the distorted female-to-male sex ratio seems to show worsening tendencies. Using detailed, two-year longitudinal chart abstraction data about delivery records of a private mission hospital in rural India, we explored if hospital birth ratio data differed in comparison to regional data, and what demographic and contextual variables may have influenced these outcomes. Using quantitative chart abstraction and qualitative contextual data, study results showed the female-to-male ratio was lower than the reported state ratio at birth. In the context of India’s patriarchal structure, with its strong son preference, women are under tremendous pressure or coerced to access community-based, sex-selective identification and female fetus abortion. Nurses may be key to turning the tide. PMID:28286369

  17. Lack of a Y-Chromosomal Complement in the Majority of Gestational Trophoblastic Neoplasms

    Directory of Open Access Journals (Sweden)

    Kai Lee Yap

    2010-01-01

    Full Text Available Gestational trophoblastic neoplasms (GTNs are a rare group of neoplastic diseases composed of choriocarcinomas, placental site trophoblastic tumors (PSTTs and epithelioid trophoblastic tumors (ETTs. Since these tumors are derivatives of fetal trophoblastic tissue, approximately 50% of GTN cases are expected to originate from a male conceptus and carry a Y-chromosomal complement according to a balanced sex ratio. To investigate this hypothesis, we carried out a comprehensive analysis by genotyping a relatively large sample size of 51 GTN cases using three independent sex chromosome genetic markers; Amelogenin, Protein Kinase and Zinc Finger have X and Y homologues that are distinguishable by their PCR product size. We found that all cases contained the X-chromosomal complement while only five (10% of 51 tumors harbored the Y-chromosomal complement. Specifically, Y-chromosomal signals were detected in one (5% of 19 choriocarcinomas, one (7% of 15 PSTTs and three (18% of 17 ETTs. The histopathological features of those with a Y-chromosome were similar to those without. Our results demonstrate the presence of a Y-chromosomal complement in GTNs, albeit a low 10% of cases. This shortfall of Y-chromosomal complements in GTNs may reinforce the notion that the majority of GTNs are derived from previous molar gestations.

  18. Female-biased sex ratios in marine pelagic copepods: Comment on Gusmao et al. (2013)

    DEFF Research Database (Denmark)

    Hirst, Andrew G.; Bonnet, D; Conway, DVP

    2013-01-01

    Gusmao et al. (2013; Mar Ecol Prog Ser 482:279-298) review causes of sex ratio skew in pelagic copepods and in doing so repeatedly dispute the paper of Hirst et al. (2010) ‘Does predation control adult sex ratios and longevities in marine pelagic copepods?’ Here we respond to some important error...... in their citation of our paper and briefly highlight where future work is needed in order to attribute the causes of strong sex ratio skew seen in some copepod families......Gusmao et al. (2013; Mar Ecol Prog Ser 482:279-298) review causes of sex ratio skew in pelagic copepods and in doing so repeatedly dispute the paper of Hirst et al. (2010) ‘Does predation control adult sex ratios and longevities in marine pelagic copepods?’ Here we respond to some important errors...

  19. Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis.

    Science.gov (United States)

    Scherb, Hagen; Kusmierz, Ralf; Voigt, Kristina

    2013-08-15

    The ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature. By the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation. A synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90. If the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations.

  20. Demasculinization of the Anopheles gambiae X chromosome

    Directory of Open Access Journals (Sweden)

    Magnusson Kalle

    2012-05-01

    Full Text Available Abstract Background In a number of organisms sex-biased genes are non-randomly distributed between autosomes and the shared sex chromosome X (or Z. Studies on Anopheles gambiae have produced conflicting results regarding the underrepresentation of male-biased genes on the X chromosome and it is unclear to what extent sexual antagonism, dosage compensation or X-inactivation in the male germline, the evolutionary forces that have been suggested to affect the chromosomal distribution of sex-biased genes, are operational in Anopheles. Results We performed a meta-analysis of sex-biased gene expression in Anopheles gambiae which provides evidence for a general underrepresentation of male-biased genes on the X-chromosome that increased in significance with the observed degree of sex-bias. A phylogenomic comparison between Drosophila melanogaster, Aedes aegypti and Culex quinquefasciatus also indicates that the Anopheles X chromosome strongly disfavours the evolutionary conservation of male-biased expression and that novel male-biased genes are more likely to arise on autosomes. Finally, we demonstrate experimentally that transgenes situated on the Anopheles gambiae X chromosome are transcriptionally silenced in the male germline. Conclusion The data presented here support the hypothesis that the observed demasculinization of the Anopheles X chromosome is driven by X-chromosome inactivation in the male germline and by sexual antagonism. The demasculinization appears to be the consequence of a loss of male-biased expression, rather than a failure in the establishment or the extinction of male-biased genes.

  1. Change in schistosome sex ratio under the influence of a biotic environmental-related factor.

    Science.gov (United States)

    Moné, H

    1997-04-01

    Schistosoma mansoni is a dioecious trematode responsible for intestinal schistosomiasis in man. The sex ratio was determined for S. mansoni adults derived from cercariae obtained from infected Biomphalaria glabrata maintained in the presence of the nonvector molluse. Marisa cornuarietis. The presence of M. cornuarietis is responsible for enhanced growth of B. glabrata and for a change in the sex ratio of the schistosome, which becomes more male-biased as compared to control snails maintained in aquaria lacking M. cornuarietis. This is the first time the presence of another species in the environment has been shown to influence schistosome sex ratios. Two nonexclusive hypotheses are proposed to explain this variation in the sex ratio: sexual competition between male and female sporocysts; and sex reversal.

  2. Pre-ovulation control of hatchling sex ratio in the Seychelles warbler

    NARCIS (Netherlands)

    Komdeur, J; Magrath, MJL; Krackow, S

    2002-01-01

    Females of some bird species have a high degree of control over the sex ratio of their offspring at laying. Although several mechanisms have been put forward to explain how females might control the sex of their eggs, virtually nothing is known. As females are the heterogametic sex in birds,

  3. Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami.

    Directory of Open Access Journals (Sweden)

    Madison T Ortega

    Full Text Available Sexual differentiation across taxa may be due to genetic sex determination (GSD and/or temperature sex determination (TSD. In many mammals, males are heterogametic (XY; whereas females are homogametic (XX. In most birds, the opposite is the case with females being heterogametic (ZW and males the homogametic sex (ZZ. Many reptile species lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps. There has been speculation that Australian Brush-turkeys (Alectura lathami exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Australian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae.

  4. Offspring sex ratio is related to paternal train elaboration and yolk corticosterone in peafowl.

    Science.gov (United States)

    Pike, Thomas W; Petrie, Marion

    2005-06-22

    Several recent experimental studies have provided strong evidence for the ability of birds to manipulate the sex ratio of their offspring prior to laying. Using a captive population of peafowl (Pavo cristatus), we tested experimentally the effects of paternal attractiveness on offspring sex ratio, and related sex ratio deviations to egg-yolk concentrations of testosterone, 17beta-estradiol and corticosterone. When females were mated to males whose attractiveness had been experimentally reduced by removing prominent eyespot feathers from their trains, they produced significantly more female offspring, had significantly higher yolk corticosterone concentrations and tended to have lower levels of yolk testosterone than when mated to the same males with their full complement of feathers. Concentrations of 17beta-estradiol did not vary consistently with sex ratio biases. These findings add to the small number of studies providing experimental evidence that female birds can control the primary sex ratio of their offspring in response to paternal attractiveness, and highlight the possibility that corticosterone and perhaps testosterone are involved in the sex manipulation process in birds.

  5. The impact of sex ratio and economic status on local birth rates.

    Science.gov (United States)

    Chipman, A; Morrison, E

    2013-04-23

    Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female-female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction.

  6. An unstable social environment affects sex ratio in guinea pigs : an adaptive maternal effect?

    NARCIS (Netherlands)

    Kemme, Kristina; Kaiser, Sylvia; von Engelhardt, Nikolaus; Wewers, Dirk; Groothuis, Ton; Sachser, Norbert

    2009-01-01

    Evolutionary theory suggests that offspring sex should be adjusted to environmental conditions in order to maximize future reproductive success. In several animal taxa environmental factors indeed affect the secondary sex ratio. In humans, changes in the sex ratio at birth have been associated with

  7. SRY mutation analysis by next generation (deep sequencing in a cohort of chromosomal Disorders of Sex Development (DSD patients with a mosaic karyotype

    Directory of Open Access Journals (Sweden)

    Hersmus Remko

    2012-11-01

    Full Text Available Abstract Background The presence of the Y-chromosome or Y chromosome-derived material is seen in 4-60% of Turner syndrome patients (Chromosomal Disorders of Sex Development (DSD. DSD patients with specific Y-chromosomal material in their karyotype, the GonadoBlastoma on the Y-chromosome (GBY region, have an increased risk of developing type II germ cell tumors/cancer (GCC, most likely related to TSPY. The Sex determining Region on the Y gene (SRY is located on the short arm of the Y-chromosome and is the crucial switch that initiates testis determination and subsequent male development. Mutations in this gene are responsible for sex reversal in approximately 10-15% of 46,XY pure gonadal dysgenesis (46,XY DSD cases. The majority of the mutations described are located in the central HMG domain, which is involved in the binding and bending of the DNA and harbors two nuclear localization signals. SRY mutations have also been found in a small number of patients with a 45,X/46,XY karyotype and might play a role in the maldevelopment of the gonads. Methods To thoroughly investigate the presence of possible SRY gene mutations in mosaic DSD patients, we performed next generation (deep sequencing on the genomic DNA of fourteen independent patients (twelve 45,X/46,XY, one 45,X/46,XX/46,XY, and one 46,XX/46,XY. Results and conclusions The results demonstrate that aberrations in SRY are rare in mosaic DSD patients and therefore do not play a significant role in the etiology of the disease.

  8. Sex ratio distribution and fecundity of the claroteid catfish Clarotes ...

    African Journals Online (AJOL)

    Sex ratio distribution and fecundity of Clarotes laticeps were investigated between January 2010 and December 2012 in the lower River Niger. Samples were collected every two weeks for 36 months from six sampling sites, using a combination of baited longlines, gill nets and cast nets. Sexes of captured specimens were ...

  9. Quantitative sexing (Q-Sexing) and relative quantitative sexing (RQ ...

    African Journals Online (AJOL)

    samer

    Key words: Polymerase chain reaction (PCR), quantitative real time polymerase chain reaction (qPCR), quantitative sexing, Siberian tiger. INTRODUCTION. Animal molecular sexing .... 43:3-12. Ellegren H (1996). First gene on the avian W chromosome (CHD) provides a tag for universal sexing of non-ratite birds. Proc.

  10. Neurocognitive Outcomes of Individuals with a Sex Chromosome Trisomy: XXX, XYY, or XXY--A Systematic Review

    Science.gov (United States)

    Leggett, Victoria; Jacobs, Patricia; Nation, Kate; Scerif, Gaia; Bishop, Dorothy V. M.

    2010-01-01

    Aim: To review systematically the neurodevelopmental characteristics of individuals with sex chromosome trisomies (SCTs). Method: A bibliographic search identified English-language articles on SCTs. The focus was on studies unbiased by clinical referral, with power of at least 0.69 to detect an effect size of 1.0. Results: We identified 35…

  11. Socioeconomic status influences sex ratios in a Chinese rural population.

    Science.gov (United States)

    Luo, Liqun; Ding, Rui; Gao, Xiali; Sun, Jingjing; Zhao, Wei

    2017-01-01

    According to the logic of the Trivers-Willard hypothesis, in a human population, if socioeconomic status is transmitted across generations to some extent, and if sons of high-status parents tend to have higher reproductive success than daughters, while daughters of low-status parents tend to have higher reproductive success than sons, then we should expect that offspring sex ratio is positively associated with socioeconomic status. This study examines whether the assumptions and prediction of this hypothesis apply to a rural population in northern China. Results show that (1) current family socioeconomic status is positively related to family head's father's socioeconomic status in around 1950, (2) low-status family heads have more grandchildren through their daughters than their sons, whereas high- or middle-status family heads have more grandchildren through sons, and (3) as family heads' status increases, they tend to produce a higher offspring sex ratio. Therefore, the assumptions and prediction of the hypothesis are met in the study population. These results are discussed in reference to past studies on sex ratio manipulation among humans.

  12. Strong but variable associations between social dominance and clutch sex ratio in a colonial corvid

    NARCIS (Netherlands)

    Salomons, H. M.; Dijkstra, C.; Verhulst, S.

    2008-01-01

    We studied primary sex ratio of clutches in relation to social dominance for 6 years in a colony of free-living jackdaws, a small corvid. Social dominance was strongly associated with clutch sex ratio, with the difference in clutch sex ratio between the most and least dominant pairs being 30-40%. To

  13. Phenotypic sex ratios of Atriplex canescens shrubs in relation to cattle browsing

    Science.gov (United States)

    Andres F. Cibils; David M. Swift; Richard H. Hart

    2001-01-01

    Previous studies conducted at our research site on the shortgrass steppe in Colorado showed that phenotypic sex ratios of tetraploid fourwing saltbush (Atriplex canescens Pursh [Nutt]) shrubs were less female biased in grazed pastures than in adjacent exclosures. The potential effects of cattle browsing on shrub sex ratios were studied both in the field and in a...

  14. Sex differences in life span: Females homozygous for the X chromosome do not suffer the shorter life span predicted by the unguarded X hypothesis.

    Science.gov (United States)

    Brengdahl, Martin; Kimber, Christopher M; Maguire-Baxter, Jack; Friberg, Urban

    2018-03-01

    Life span differs between the sexes in many species. Three hypotheses to explain this interesting pattern have been proposed, involving different drivers: sexual selection, asymmetrical inheritance of cytoplasmic genomes, and hemizygosity of the X(Z) chromosome (the unguarded X hypothesis). Of these, the unguarded X has received the least experimental attention. This hypothesis suggests that the heterogametic sex suffers a shortened life span because recessive deleterious alleles on its single X(Z) chromosome are expressed unconditionally. In Drosophila melanogaster, the X chromosome is unusually large (∼20% of the genome), providing a powerful model for evaluating theories involving the X. Here, we test the unguarded X hypothesis by forcing D. melanogaster females from a laboratory population to express recessive X-linked alleles to the same degree as males, using females exclusively made homozygous for the X chromosome. We find no evidence for reduced life span or egg-to-adult viability due to X homozygozity. In contrast, males and females homozygous for an autosome both suffer similar, significant reductions in those traits. The logic of the unguarded X hypothesis is indisputable, but our results suggest that the degree to which recessive deleterious X-linked alleles depress performance in the heterogametic sex appears too small to explain general sex differences in life span. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

  15. Unusual arrangement and behaviour of the sex chromosomes of Aphodius (Agolius abdominalis Bonelli, 1812, and comparison with A. (A. bonvouloiri Harold, 1860 (Coleoptera: Aphodiidae

    Directory of Open Access Journals (Sweden)

    Robert Angus

    2009-12-01

    Full Text Available Aphodius abdominalis Bonelli, 1812 is shown to have a karyotype comprising nine pairs of autosomes and sex chromosomes which are X0 (male, XX (female. At first metaphase of meiosis the X chromosome is linked to an autosomal bivalent by a darkly staining area of the cytoplasm, resembling the Xy p arrangement typical of Aphodius species, but giving nine, rather than 10, elements in the nucleus. C-banding, which shows the centromeres, confirms this unusual arrangement. A. bonvouloiri, the only other known species of subgenus Agolius Mulsant et Rey, 1869, has a male karyotype with nine pairs of autosomes and Xy sex chromosomes. No preparations of its meiosis are available.

  16. Skewed Marriage Markets and Sex Ratios of Finnish People in their Twenties

    Directory of Open Access Journals (Sweden)

    Lassi Lainiala

    2014-03-01

    Full Text Available This article studies variation in regional sex ratios in Finland and outlines potential implications of the skewed sex ratios for family formation patterns. Difficulties in finding a suitable partner are typically mentioned as one of the most important reasons for remaining childless, and we explore if this reason is apparent structurally at the regional macro level. We found significant variation in sex ratios in age-groups 18–30 at the regional and sub-regional levels. Of the whole 20–29-year old population in Finland, almost 50 percent live in sub-region areas with a male surplus. As expected, a higher proportion of men compared to women appears to increase fertility of women in younger age groups. Contrary to expectations, high male-female ratios were not related to higher proportion of women living with a partner

  17. Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

    Science.gov (United States)

    2013-01-01

    Background The ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature. Presentation of the hypothesis By the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation. Testing of the hypothesis A synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value < 0.0001. In Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value < 0.0001. The hypothesis may be tested by reconstruction of imports from the world markets to Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90. Implications of the hypothesis If the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations. PMID:23947741

  18. X- and Y-chromosome specific variants of the amelogenin gene allow sex determination in sheep (Ovis aries and European red deer (Cervus elaphus

    Directory of Open Access Journals (Sweden)

    Brenig B

    2005-03-01

    Full Text Available Abstract Background Simple and precise methods for sex determination in animals are a pre-requisite for a number of applications in animal production and forensics. However, some of the existing methods depend only on the detection of Y-chromosome specific sequences. Therefore, the abscence of a signal does not necessarily mean that the sample is of female origin, because experimental errors can also lead to negative results. Thus, the detection of Y- and X-chromosome specific sequences is advantageous. Results A novel method for sex identification in mammals (sheep, Ovis aries and European red deer, Cervus elaphus is described, using a polymerase chain reaction (PCR and sequencing of a part of the amelogenin gene. A partial sequence of the amelogenin gene of sheep and red deer was obtained, which exists on both X and Y chromosomes with a deletion region on the Y chromosome. With a specific pair of primers a DNA fragment of different length between the male and female mammal was amplified. Conclusion PCR amplification using the amelogenin gene primers is useful in sex identification of samples from sheep and red deer and can be applied to DNA analysis of micro samples with small amounts of DNA such as hair roots as well as bones or embryo biopsies.

  19. Three loci on mouse chromosome 5 and 10 modulate sex determination in XX Ods/+ mice.

    Science.gov (United States)

    Poirier, Christophe; Moran, Jennifer L; Kovanci, Ertug; Petit, Deborah C; Beier, David R; Bishop, Colin E

    2007-07-01

    In mouse, XY embryos are committed to the male sex determination pathway after the transient expression of the Y-linked Sry gene in the Sertoli cell lineage between 10.5 and 12.5 dpc. In the C57BL/6J strain, male sex determination program can be modulated by some autosomal genes. The C57BL/6J alleles at these autosomal loci can antagonize male sex determination in combination with specific Sry alleles. In this report, the authors have identified an effect of these C57BL/6J specific alleles in combination with a mutated Sox9 allele, Sox9(Ods). Authors report the mapping of three of these genetic loci on mouse chromosome 5 and 10 in a backcross of the Ods mutation to the C57BL/6J background. Our study confirms the importance of the strain C57BL/6J for the investigation of the genetic mechanisms that control sex determination.

  20. Chromosomes of South American Bufonidae (Amphibia, Anura Chromosomes of South American Bufonidae (Amphibia, Anura

    Directory of Open Access Journals (Sweden)

    Brum Zorrilla N.

    1973-09-01

    Full Text Available Karyotypes of eight of South American Bufonidae were studied: B.ictericus, B. spinulosus spinulosus, B. arenarum, B. g. fernandezae, B. g. d'orbignyi, B. crucifer, B. paracnemis and B. marinus. In all species 2n = 22 chromosomes were found. Neither heteromorphic pairs of chromosomes nor bivalents with characteristic morphology and behavior of sex chromosomesduring male meiosis were observed in any species.Karyotypes of eight of South American Bufonidae were studied: B.ictericus, B. spinulosus spinulosus, B. arenarum, B. g. fernandezae, B. g. d'orbignyi, B. crucifer, B. paracnemis and B. marinus. In all species 2n = 22 chromosomes were found. Neither heteromorphic pairs of chromosomes nor bivalents with characteristic morphology and behavior of sex chromosomesduring male meiosis were observed in any species.

  1. Transgenerational plasticity mitigates the impact of global warming to offspring sex ratios.

    Science.gov (United States)

    Donelson, Jennifer M; Munday, Philip L

    2015-08-01

    Global warming poses a threat to organisms with temperature-dependent sex determination because it can affect operational sex ratios. Using a multigenerational experiment with a marine fish, we provide the first evidence that parents developing from early life at elevated temperatures can adjust their offspring gender through nongenetic and nonbehavioural means. However, this adjustment was not possible when parents reproduced, but did not develop, at elevated temperatures. Complete restoration of the offspring sex ratio occurred when parents developed at 1.5 °C above the present-day average temperature for one generation. However, only partial improvement in the sex ratio occurred at 3.0 °C above average conditions, even after two generations, suggesting a limitation to transgenerational plasticity when developmental temperature is substantially increased. This study highlights the potential for transgenerational plasticity to ameliorate some impacts of climate change and that development from early life may be essential for expression of transgenerational plasticity in some traits. © 2015 John Wiley & Sons Ltd.

  2. An Unusual Accumulation of Ribosomal Multigene Families and Microsatellite DNAs in the XX/XY Sex Chromosome System in the Trans-Andean Catfish Pimelodella cf. chagresi (Siluriformes:Heptapteridae).

    Science.gov (United States)

    Conde-Saldaña, Cristhian Camilo; Barreto, Cynthia Aparecida Valiati; Villa-Navarro, Francisco Antonio; Dergam, Jorge Abdala

    2018-02-01

    This work constitutes the first cytogenetic characterization of a trans-Andean species of Heptapteridae. The catfish Pimelodella cf. chagresi from the Upper Rio Magdalena was studied, applying standard cytogenetic techniques (Giemsa, C-banding, and argyrophilic nucleolar organizer region [Ag-NOR]) and fluorescence in situ hybridization techniques using repetitive DNA probes: microsatellites (CA 15 and GA 15 ) and ribosomal RNA (rRNA) multigene families (18S and 5S recombinant DNA [rDNA] probes). The species showed a unique diploid chromosome number 2n = 50 (32m [metacentrics] +14sm [submetacentrics] +4st [subtelocentrics]) and a XX/XY sex chromosomal system, where the heteromorphic Y-chromosome revealed a conspicuous accumulation of all the assayed domains of repetitive DNA. P. cf. chagresi karyotype shares common features with other Heptapteridae, such as the predominance of metacentric and submetacentric chromosomes, and one pair of subtelomeric nucleolar organizer regions (NORs). These results reflect an independent karyological identity of a trans-Andean species and the relevance of repetitive DNA sequences in the process of sex chromosome differentiation in fish; it is the first case of syntenic accumulation of rRNA multigene families (18S and 5S rDNA) and microsatellite sequences (CA 15 and GA 15 ) in a differentiated sex chromosome in Neotropical fish.

  3. The potential pitfalls of studying adult sex ratios at aggregate levels in humans

    NARCIS (Netherlands)

    Pollet, Thomas V.; Stoevenbelt, Andrea H.; Kuppens, Toon

    2017-01-01

    Human adult sex ratios have been studied extensively across the biological and social sciences. While several studies have examined adult sex ratio effects in a multilevel perspective, many studies have focused on effects at an aggregated level only. In this paper, we review some key issues relating

  4. [The sex ratio at birth: a retrospective review and commentary].

    Science.gov (United States)

    Aubenque, M

    1989-01-01

    Trends in the sex ratio are examined, and the possible effect of new biotechnologies on sex preselection is discussed. "We recall that this ratio is very stable, around 105 males for 100 females (live births). However, in France, a slight decreasing trend during the 19th century can be observed (from 107 to 104). At the present time this ratio seems to be maintained at a level of 105.3. The great demographic perturbations, particularly caused by wars, have been marked by a slight but notable increase in the indicator (106) when natality rises again after a deep depression. The variations, always small, of this indicator are more dependent on the male than on female natality, for reasons that are unclear." A comment by Paul Damiani is included (pp. 99-102). (SUMMARY IN ENG) excerpt

  5. The sex ratio of offspring is associated with the mothers' age at menarche

    DEFF Research Database (Denmark)

    Fukuda, Misao; Fukuda, Kiyomi; Shimizu, Takashi

    2011-01-01

    BACKGROUND Early menarcheal age is a risk factor for breast and ovarian cancers and is also associated with an increased spontaneous abortion rate. The aim of this study was to investigate whether there is a link between early menarcheal age and the offspring sex ratio. METHODS We recorded the sex...... of 21208 live born infants, all singletons, born to 10 847 premenopausal women (mean attending age: 37.5 ± 7.2 years, range 22-54) who attended our clinics for obstetrical and gynaecological assessment. We calculated the sex ratio of newborn infants in relation to the mothers' age of menarche (from 9 to 18...... years) and to the number of infants per woman (i.e. fertility index). RESULTS A low offspring sex ratio (males/females) of 0.800 was observed in mothers who entered menarche at the age of 9 years; the odds ratio (OR) (95% confidence intervals) compared with those of control group with menarche at age 14...

  6. Identification of a Novel Retrotransposon with Sex Chromosome-Specific Distribution in Silene latifolia

    Czech Academy of Sciences Publication Activity Database

    Králová, Tereza; Čegan, Radim; Kubát, Zdeněk; Vrána, Jan; Vyskot, Boris; Vogel, Ivan; Kejnovský, Eduard; Hobza, Roman

    2014-01-01

    Roč. 143, 1-3 (2014), s. 87-95 ISSN 1424-8581 R&D Projects: GA MŠk(CZ) LM2010005; GA ČR(CZ) GAP501/10/0102; GA ČR(CZ) GAP501/12/2220; GA ČR(CZ) GAP305/10/0930; GA ČR(CZ) GA522/09/0083; GA MŠk(CZ) LO1204 Institutional support: RVO:68081707 Keywords : Microdissection * Sex chromosomes * Silene latifolia (white campion) Subject RIV: BO - Biophysics; EF - Botanics (UEB-Q) Impact factor: 1.561, year: 2014

  7. The fate of W chromosomes in hybrids between wild silkmoths, Samia cynthia ssp.: no role in sex determination and reproduction

    Czech Academy of Sciences Publication Activity Database

    Yoshido, Atsuo; Marec, František; Sahara, K.

    2016-01-01

    Roč. 116, č. 5 (2016), s. 424-433 ISSN 0018-067X R&D Projects: GA ČR(CZ) GA14-22765S Grant - others:The European Union Seventh Framework Programme (FP7/2007-2013)(CZ) 316304 Program:FP7 Institutional support: RVO:60077344 Keywords : hybrids * sex chromosomes * sex determination Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.961, year: 2016

  8. Flock sizes and sex ratios of canvasbacks in Chesapeake Bay and North Carolina

    Science.gov (United States)

    Haramis, G.M.; Derleth, E.L.; Link, W.A.

    1994-01-01

    Knowledge of the distribution, size, and sex ratios of flocks of wintering canvasbacks (Aythya valisineria) is fundamental to understanding the species' winter ecology and providing guidelines for management. Consequently, in winter 1986-87, we conducted 4 monthly aerial photographic surveys to investigate temporal changes in distribution, size, and sex ratios of canvasback flocks in traditional wintering areas of Chesapeake Bay and coastal North Carolina. Surveys yielded 35mm imagery of 194,664 canvasbacks in 842 flocks. Models revealed monthly patterns of flock size in North Carolina and Virginia, but no pattern of change in Maryland. A stepwise analysis of flock size and sex ratio fit a common positive slope (increasing proportion male) for all state-month datasets, except for North Carolina in February where the slope was larger (P lt 0.001). State and month effects on intercepts were significant (P lt 0.001) and confirmed a previously identified latitudinal gradient in sex ratio in the survey region. There was no relationship between flock purity (% canvasbacks vs. other species) and flock size except in North Carolina in January, February, and March when flock purity was related to flock size. Contrasting characteristics in North Carolina with regard to flock size (larger flocks) and flock purity suggested that proximate factors were reinforcing flocking behavior and possibly species fidelity there. Of possible factors, the need to locate foraging sites within this large, open-water environment was hypothesized to be of primary importance. Comparison of January 1981 and 1987 sex ratios indicated no change in Maryland, but lower (P lt 0.05) canvasback sex ratios (proportion male) in Virginia and North Carolina.

  9. Population sex ratios: another consideration in the reintroduction - reinforcement debate?

    Directory of Open Access Journals (Sweden)

    Sergio A Lambertucci

    Full Text Available Reintroduction or reinforcement (RorR of wild populations is a common conservation strategy. Many conservation projects involve the release of individuals of poorly studied species. This may lead to inefficient results or negative impacts on the conservation efforts. Here, we provide new insights into the conservation implications and potential consequences of a skew in the sex ratio of released birds and of the number of birds supplemented for the demography of a long-lived dimorphic bird species, the Andean condor (Vulturgryphus. We demonstrate that a RorR conservation program may be less effective in conserving a species if the sex ratios of the releases and the recipient populations are not considered. We also show that releases can reduce population declines but only if carried out over long periods (i.e., several decades. This can mean high costs for release programs and the added challenge of maintaining programs over time. If RorR programs are to be implemented, bearing in mind the importance of properly assessing their effectiveness, we urge conservation researchers and managers to consider the implications of sex ratio biases for wild populations, and particularly for dimorphic species with sexually despotic behaviour.

  10. Maintaining access to safe abortion and reducing sex ratio imbalances in Asia.

    Science.gov (United States)

    Ganatra, Bela

    2008-05-01

    High sex ratios at birth (108 boys to 100 girls or higher) are seen in China, Taiwan, South Korea and parts of India and Viet Nam. The imbalance is the result of son preference, accentuated by declining fertility. Prenatal sex detection with ultrasound followed by second trimester abortion is one of the ways sex selection manifests itself, but it is not the causative factor. Advocates and governments seeking to reverse this imbalance have largely prohibited sex detection tests and/or sex selective abortion, assuming these measures would reverse the trend. Such policies have been difficult to enforce and have met with only limited success. At the same time, such policies are starting to have adverse effects on the already limited access to safe and legal second trimester abortion for reasons other than sex selection. Moreover, the sex selection issue is being used as a platform for anti-abortion rhetoric by certain groups. Maintaining access to safe abortion and achieving a decline in high sex ratios are both important goals. Both are possible if the focus shifts to addressing the conditions that drive son preference.

  11. The sex ratio of siblings of individuals with a history of developmental language disorder

    DEFF Research Database (Denmark)

    Mouridsen, Svend Erik; Hauschild, Karen-Marie

    2010-01-01

    There is a well documented predominance of males diagnosed with neurodevelopmental disorders. The influence of sex steroids upon brain development has been suggested to mediate sex differences in developmental psychopathology, and has been epitomized in the 'extreme male brain theory......'. The objective of this study was to extend previous studies dealing with the extreme male brain theory and to study the sex ratio (proportion of males) in the siblings of 469 individuals with a developmental language disorder (DLD) who were consecutively assessed in the same clinic during a period of 10 years....... Among their 908 live-born siblings, 503 were males and 405 females. This yields a sex ratio of 0.554, which is significantly higher than the Danish live birth sex ratio of 0.514 over the same period (P = 0.02). Our findings are consistent with the hypothesis that male sex hormones may be implicated...

  12. The mystery of missing female children in the Caucasus: an analysis of sex ratios by birth order.

    Science.gov (United States)

    Michael, Marc; King, Lawrence; Guo, Liang; McKee, Martin; Richardson, Erica; Stuckler, David

    2013-06-01

    Official data on sex ratios at birth suggest a rise in sex-selective abortions in some post-Soviet states following the introduction of ultrasonography. However, questions remain about the validity of official data in these nations as well as whether the high sex ratios at birth are a statistical artifact. Trends in sex ratios at birth from 1985 to 2009 for 12 post-Soviet states were examined using vital registration data. For the three countries that had had a Demographic and Health Survey (DHS) in 2005-2010 (Armenia, Azerbaijan and Moldova), survey data were used to calculate sex ratios at birth according to birth order, and vital registration data for 2010 were used to estimate the number of "missing" female births (if any). Official data revealed elevated sex ratios at birth in Armenia (117), Azerbaijan (116) and Georgia (121), but not in other post-Soviet states. According to DHS data, sex ratios were high in Armenia and Azerbaijan for first births (138 and 113, respectively); if the first child was a girl, the sex ratio in Armenia was even higher for the second birth (154). Overall, the number of girls born in these countries in 2010 was 10% lower than expected, consistent with 1,972 sex-selective abortions in Armenia and 8,381 in Azerbaijan. Sex ratios did not vary by birth order in Moldova. Sex-selective abortion appears to be common in Azerbaijan and Armenia. Family planning and legal interventions are needed to address this issue.

  13. Horse domestication and conservation genetics of Przewalski's horse inferred from sex chromosomal and autosomal sequences.

    Science.gov (United States)

    Lau, Allison N; Peng, Lei; Goto, Hiroki; Chemnick, Leona; Ryder, Oliver A; Makova, Kateryna D

    2009-01-01

    Despite their ability to interbreed and produce fertile offspring, there is continued disagreement about the genetic relationship of the domestic horse (Equus caballus) to its endangered wild relative, Przewalski's horse (Equus przewalskii). Analyses have differed as to whether or not Przewalski's horse is placed phylogenetically as a separate sister group to domestic horses. Because Przewalski's horse and domestic horse are so closely related, genetic data can also be used to infer domestication-specific differences between the two. To investigate the genetic relationship of Przewalski's horse to the domestic horse and to address whether evolution of the domestic horse is driven by males or females, five homologous introns (a total of approximately 3 kb) were sequenced on the X and Y chromosomes in two Przewalski's horses and three breeds of domestic horses: Arabian horse, Mongolian domestic horse, and Dartmoor pony. Five autosomal introns (a total of approximately 6 kb) were sequenced for these horses as well. The sequences of sex chromosomal and autosomal introns were used to determine nucleotide diversity and the forces driving evolution in these species. As a result, X chromosomal and autosomal data do not place Przewalski's horses in a separate clade within phylogenetic trees for horses, suggesting a close relationship between domestic and Przewalski's horses. It was also found that there was a lack of nucleotide diversity on the Y chromosome and higher nucleotide diversity than expected on the X chromosome in domestic horses as compared with the Y chromosome and autosomes. This supports the hypothesis that very few male horses along with numerous female horses founded the various domestic horse breeds. Patterns of nucleotide diversity among different types of chromosomes were distinct for Przewalski's in contrast to domestic horses, supporting unique evolutionary histories of the two species.

  14. Sex ratios in juveniles and adults of Dichroplus maculipennis (Blanchard and Borellia bruneri (Rehn (Orthoptera: Acrididae

    Directory of Open Access Journals (Sweden)

    Yanina Mariottini

    2015-06-01

    Full Text Available Dichroplus maculipennis and Borellia bruneri are two of the 18 grasshopper species of actual or potential economic relevance as pests in Argentina. The objective of this study was to estimate the sex ratios for adults and older nymphs of D. maculipennis and B. bruneri in the field, and analyze possible temporal variations. The study was conducted during seven seasons (2005-06 to 2011-12 in representative plant communities of the southern Pampas region. A total of 4536 individuals of D. maculipennis, and 6038 individuals of B. bruneri were collected. The sex ratio registered in older nymphs for D. maculipennis and B. bruneri did not deviate from a 1:1 ratio (p > 0.05, suggesting that these species have such a primary sex ratio. However, a significant bias in sex composition in adults of both species was observed (p < 0.05. The sex ratio in adults of D. maculipennis was different in five of the 18 sampling dates carried out. In three sampling dates it was biased toward males, while in the other two it was biased toward females. Taking into account the sex ratio by sampling season, significant differences were recorded in two seasons. In 2007-08 the sex ratio was biased toward males (1 F:2.26 M, while in 2008-09 it was biased toward females (1.35 F:1 M. The sex ratio in adults of B. bruneri was always biased toward males (p < 0.05. We conclude that results obtained in this study indicate that various factors like differential survival, dispersion, predation, among others, could have modified the primary sex ratio in these species.

  15. Roles of the Y chromosome genes in human cancers

    Directory of Open Access Journals (Sweden)

    Tatsuo Kido

    2015-06-01

    Full Text Available Male and female differ genetically by their respective sex chromosome composition, that is, XY as male and XX as female. Although both X and Y chromosomes evolved from the same ancestor pair of autosomes, the Y chromosome harbors male-specific genes, which play pivotal roles in male sex determination, germ cell differentiation, and masculinization of various tissues. Deletions or translocation of the sex-determining gene, SRY, from the Y chromosome causes disorders of sex development (previously termed as an intersex condition with dysgenic gonads. Failure of gonadal development results not only in infertility, but also in increased risks of germ cell tumor (GCT, such as gonadoblastoma and various types of testicular GCT. Recent studies demonstrate that either loss of Y chromosome or ectopic expression of Y chromosome genes is closely associated with various male-biased diseases, including selected somatic cancers. These observations suggest that the Y-linked genes are involved in male health and diseases in more frequently than expected. Although only a small number of protein-coding genes are present in the male-specific region of Y chromosome, the impacts of Y chromosome genes on human diseases are still largely unknown, due to lack of in vivo models and differences between the Y chromosomes of human and rodents. In this review, we highlight the involvement of selected Y chromosome genes in cancer development in men.

  16. Hatchling sex ratio and female mating status in the great reed warbler, Acrocephalus arundinaceus (Aves, Passeriformes): further evidence for offspring sex ratio manipulation

    Czech Academy of Sciences Publication Activity Database

    Trnka, A.; Prokop, P.; Kašová, M.; Sobeková, Karolina; Kocian, Ľ.

    2012-01-01

    Roč. 79, č. 2 (2012), s. 212-217 ISSN 1125-0003 Institutional support: RVO:68081766 Keywords : Great reed warbler * sex ratio * social polygyny Subject RIV: EG - Zoology Impact factor: 0.890, year: 2012

  17. A Multinomial Model of Fertility Choice and Offspring Sex-Ratios in India

    OpenAIRE

    Rubiana Chamarbagwala; Martin Ranger

    2007-01-01

    Fertility decline in developing countries may have unexpected demographic consequences. Although lower fertility improves nutrition, health, and human capital investments for surviving children, little is known about the relationship between fertility outcomes and female-male offspring sex-ratios. Particularly in countries with a cultural preference for sons, like India and China, fertility decline may deteriorate the already imbalanced sex-ratios. We use the fertility histories of over 90,00...

  18. Manipulation of primary sex ratio in birds : Lessons from the Homing Pigeon (Columba livia domestica)

    NARCIS (Netherlands)

    Goerlich-Jansson, Vivian C.; Muller, Martina S.; Groothuis, Ton G. G.

    2013-01-01

    Across various animal taxa not only the secondary sex ratio but also the primary sex ratio (at conception) shows significant deviations from the expected equal proportions of sons and daughters. Birds are especially intriguing to study this phenomenon as avian females are the heterogametic sex (ZW);

  19. Different male versus female breeding periodicity helps mitigate offspring sex ratio skews in sea turtles

    Directory of Open Access Journals (Sweden)

    Graeme Clive Hays

    2014-09-01

    Full Text Available The implications of climate change for global biodiversity may be profound with those species with little capacity for adaptation being thought to be particularly vulnerable to warming. A classic case of groups for concern are those animals exhibiting temperature-dependent sex-determination (TSD, such as sea turtles, where climate warming may produce single sex populations and hence extinction. We show that, globally, female biased hatchling sex ratios dominate sea turtle populations (exceeding 3:1 in >50% records, which, at-a-glance, reiterates concerns for extinction. However, we also demonstrate that more frequent breeding by males, empirically shown by satellite tracking 23 individuals and supported by a generalized bio-energetic life history model, generates more balanced operational sex ratios (OSRs. Hence, concerns of increasingly skewed hatchling sex ratios and reduced population viability are less acute than previously thought for sea turtles. In fact, in some scenarios skewed hatchling sex ratios in groups with TSD may be adaptive to ensure optimum OSRs.

  20. Determination of sex-ratio by birth order in an urban community in Manipur.

    Science.gov (United States)

    Brogen, Akoijam S; Shantibala, K; Rajkumari, Bishwalata; Laishram, Jalina

    2009-01-01

    To determine the sex ratio by birth order and to assess the sex preference of the couples in an urban community. A cross sectional study, in an urban community in Manipur, was conducted among the currently married couples. Data on background characteristics of the couple, family pedigree chart (of the offspring) including history of abortion, stillbirth, death of child of the couple, sex preference and Pre-natal Diagnostic Techniques (Regulation and Prevention of Misuse) Act [PNDT Act] were collected through a structured interview. Data were analyzed using descriptive and chi-square statistics. There were a total of 1777 births to the 855 couples interviewed. There were 900 females per 1000 males for the 1st birth order but the sex ratio was favorable towards females in the 2nd, 3rd and 4th birth orders. Among both the husbands and wives, being more educated was significantly associated (p<0.05) with preferring lesser number of children, using new technology for sex selection and having heard of the PNDT Act. Majority of those who wanted to use new technology for sex selection (128, 56.6%) preferred to have male child. Sex ratio in this community was favorable towards females, though it was less among the first born babies.

  1. Influence of electromagnetic pulse on the offspring sex ratio of male BALB/c mice.

    Science.gov (United States)

    Li, Jin-Hui; Jiang, Da-Peng; Wang, Ya-Feng; Yan, Jia-Jia; Guo, Qi-Yan; Miao, Xia; Lang, Hai-Yang; Xu, Sheng-Long; Liu, Jun-Ye; Guo, Guo-Zhen

    2017-09-01

    Public concern is growing about the exposure to electromagnetic fields (EMF) and its effect on male reproductive health. Detrimental effect of EMF exposure on sex hormones, reproductive performance and sex-ratio was reported. The present study was designed to clarify whether paternal exposure to electromagnetic pulse (EMP) affects offspring sex ratio in mice. 50 male BALB/c mice aged 5-6 weeks were exposed to EMP daily for 2 weeks before mated with non-exposed females at 0d, 7d, 14d, 21d and 28d after exposure. Sex hormones including total testosterone, LH, FSH, and GnRH were detected using radioimmunoassay. The sex ratio was examined by PCR and agarose gel electrophoresis. The results of D0, D21 and D28 showed significant increases compared with sham-exposed groups. The serum testosterone increased significantly in D0, D14, D21, and D28 compared with sham-exposed groups (p<0.05). Overall, this study suggested that EMP exposure may lead to the disturbance of reproductive hormone levels and affect the offspring sex ratio. Copyright © 2017. Published by Elsevier B.V.

  2. The eXtroardinarY Babies Study: Natural History of Health and Neurodevelopment in Infants and Young Children With Sex Chromosome Trisomy

    Science.gov (United States)

    2018-01-10

    Klinefelter Syndrome; Trisomy X; XYY Syndrome; XXXY and XXXXY Syndrome; Xxyy Syndrome; Xyyy Syndrome; Xxxx Syndrome; Xxxxx Syndrome; Xxxyy Syndrome; Xxyyy Syndrome; Xyyyy Syndrome; Male With Sex Chromosome Mosaicism

  3. Recent increase in sex ratio at birth in Viet Nam.

    Directory of Open Access Journals (Sweden)

    Christophe Z Guilmoto

    Full Text Available INTRODUCTION: Since the 1980s, sex ratio at birth (male births per 100 female births has increased in many Asian countries as a result of selective abortions, but to date there has been no such evidence for Viet Nam. Our aim in this paper is to ascertain the situation with respect to sex ratio at birth in Viet Nam over the past five years. MATERIALS AND METHODS: Original data were obtained from sample population surveys in Viet Nam recording annual birth rates since 2000 of about 450,000 women, as well as from two successive birth surveys conducted for the first time in 2007 (1.1 million births. The annual population surveys include specific information on birth history and mothers' characteristics to be used for the analysis of trends and differentials in sex ratio at birth. RESULTS AND DISCUSSION: Birth history statistics indicate that the SRB in Viet Nam has recorded a steady growth since 2001. Starting from a level probably close to the biological standard of 105, the SRB reached 108 in 2005 and 112 in 2006, a value significantly above the normal level. An independent confirmation of these results comes from the surveys of births in health facilities which yielded a SRB of 110 in 2006-07. High SRB is linked to various factors such as access to modern health care, number of prenatal visits, level of higher education and employment status, young age, province of residence and prenatal sex determination. These results suggest that prenatal sex determination followed by selective abortion has recently become more common in Viet Nam. This recent trend is a consequence of various factors such as preference for sons, declining fertility, easy access to abortion, economic development as well as the increased availability of ultrasonography facilities.

  4. Recent increase in sex ratio at birth in Viet Nam.

    Science.gov (United States)

    Guilmoto, Christophe Z; Hoàng, Xuyên; Van, Toan Ngo

    2009-01-01

    Since the 1980s, sex ratio at birth (male births per 100 female births) has increased in many Asian countries as a result of selective abortions, but to date there has been no such evidence for Viet Nam. Our aim in this paper is to ascertain the situation with respect to sex ratio at birth in Viet Nam over the past five years. Original data were obtained from sample population surveys in Viet Nam recording annual birth rates since 2000 of about 450,000 women, as well as from two successive birth surveys conducted for the first time in 2007 (1.1 million births). The annual population surveys include specific information on birth history and mothers' characteristics to be used for the analysis of trends and differentials in sex ratio at birth. Birth history statistics indicate that the SRB in Viet Nam has recorded a steady growth since 2001. Starting from a level probably close to the biological standard of 105, the SRB reached 108 in 2005 and 112 in 2006, a value significantly above the normal level. An independent confirmation of these results comes from the surveys of births in health facilities which yielded a SRB of 110 in 2006-07. High SRB is linked to various factors such as access to modern health care, number of prenatal visits, level of higher education and employment status, young age, province of residence and prenatal sex determination. These results suggest that prenatal sex determination followed by selective abortion has recently become more common in Viet Nam. This recent trend is a consequence of various factors such as preference for sons, declining fertility, easy access to abortion, economic development as well as the increased availability of ultrasonography facilities.

  5. Chromosome-Centric Human Proteome Project Allies with Developmental Biology: A Case Study of the Role of Y Chromosome Genes in Organ Development.

    Science.gov (United States)

    Meyfour, Anna; Pooyan, Paria; Pahlavan, Sara; Rezaei-Tavirani, Mostafa; Gourabi, Hamid; Baharvand, Hossein; Salekdeh, Ghasem Hosseini

    2017-12-01

    One of the main goals of Chromosome-Centric Human Proteome Project is to identify protein evidence for missing proteins (MPs). Here, we present a case study of the role of Y chromosome genes in organ development and how to overcome the challenges facing MPs identification by employing human pluripotent stem cell differentiation into cells of different organs yielding unprecedented biological insight into adult silenced proteins. Y chromosome is a male-specific sex chromosome which escapes meiotic recombination. From an evolutionary perspective, Y chromosome has preserved 3% of ancestral genes compared to 98% preservation of the X chromosome based on Ohno's law. Male specific region of Y chromosome (MSY) contains genes that contribute to central dogma and govern the expression of various targets throughout the genome. One of the most well-known functions of MSY genes is to decide the male-specific characteristics including sex, testis formation, and spermatogenesis, which are majorly formed by ampliconic gene families. Beyond its role in sex-specific gonad development, MSY genes in coexpression with their X counterparts, as single copy and broadly expressed genes, inhibit haplolethality and play a key role in embryogenesis. The role of X-Y related gene mutations in the development of hereditary syndromes suggests an essential contribution of sex chromosome genes to development. MSY genes, solely and independent of their X counterparts and/or in association with sex hormones, have a considerable impact on organ development. In this Review, we present major recent findings on the contribution of MSY genes to gonad formation, spermatogenesis, and the brain, heart, and kidney development and discuss how Y chromosome proteome project may exploit developmental biology to find missing proteins.

  6. Spatio-temporal variation in the incubation duration and sex ratio of hawksbill hatchlings: implication for future management.

    Science.gov (United States)

    dei Marcovaldi, Maria A G; Santos, Armando J B; Santos, Alexsandro S; Soares, Luciano S; Lopez, Gustave G; Godfrey, Matthew H; López-Mendilaharsu, Milagros; Fuentes, Mariana M P B

    2014-08-01

    Climate change poses a unique threat to species with temperature dependent sex determination (TSD), such as marine turtles, where increases in temperature can result in extreme sex ratio biases. Knowledge of the primary sex ratio of populations with TSD is key for providing a baseline to inform management strategies and to accurately predict how future climate changes may affect turtle populations. However, there is a lack of robust data on offspring sex ratio at appropriate temporal and spatial scales to inform management decisions. To address this, we estimate the primary sex ratio of hawksbill hatchlings, Eretmochelys imbricata, from incubation duration of 5514 in situ nests from 10 nesting beaches from two regions in Brazil over the last 27 years. A strong female bias was estimated in all beaches, with 96% and 89% average female sex ratios produced in Bahia (BA) and Rio Grande do Norte (RN). Both inter-annual (BA, 88 to 99%; RN, 75 to 96% female) and inter-beach (BA, 92% to 97%; RN, 81% to 92% female) variability in mean offspring sex ratio was observed. These findings will guide management decisions in Brazil and provide further evidence of highly female-skew sex ratios in hawksbill turtles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Pengaruh Sex Ratio Ayam Arab Terhadap Fertilitas, Daya Tetas, Dan Bobot Tetas

    OpenAIRE

    Widi Astomo; Dian Septinova; Tintin Kurtini

    2016-01-01

    This study aimed to determine (1) This effect of sex ratio arabic chicken on fertility, hatchibility , and doc weight and (2) to determine the best sex ratio of effect arabic chicken on fertility, hatchability, and doc weight. This study was conducted in August 2015 at Tegalrejo village, Gadingrejo districk, Pringsewu regency.The research use 144 arabic chicken consisted of 18 males and 126 females. This research use the complete randomized design with 3 treatments and 6 times replications...

  8. Elevated mortality among birds in Chernobyl as judged from skewed age and sex ratios.

    Directory of Open Access Journals (Sweden)

    Anders Pape Møller

    Full Text Available Radiation has negative effects on survival of animals including humans, although the generality of this claim is poorly documented under low-dose field conditions. Because females may suffer disproportionately from the effects of radiation on survival due to differences in sex roles during reproduction, radiation-induced mortality may result in male-skewed adult sex ratios.We estimated the effects of low-dose radiation on adult survival rates in birds by determining age ratios of adults captured in mist nets during the breeding season in relation to background radiation levels around Chernobyl and in nearby uncontaminated control areas. Age ratios were skewed towards yearlings, especially in the most contaminated areas, implying that adult survival rates were reduced in contaminated areas, and that populations in such areas could only be maintained through immigration from nearby uncontaminated areas. Differential mortality in females resulted in a strongly male-skewed sex ratio in the most contaminated areas. In addition, males sang disproportionately commonly in the most contaminated areas where the sex ratio was male skewed presumably because males had difficulty finding and acquiring mates when females were rare. The results were not caused by permanent emigration by females from the most contaminated areas because none of the recaptured birds had changed breeding site, and the proportion of individuals with morphological abnormalities did not differ significantly between the sexes for areas with normal and higher levels of contamination.These findings are consistent with the hypothesis that the adult survival rate of female birds is particularly susceptible to the effects of low-dose radiation, resulting in male skewed sex ratios at high levels of radiation. Such skewed age ratios towards yearlings in contaminated areas are consistent with the hypothesis that an area exceeding 30,000 km(2 in Chernobyl's surroundings constitutes an

  9. Lunar cycles at mating do not influence sex ratio at birth in horses.

    Science.gov (United States)

    Aguilar, J J; Cuervo-Arango, J; Santa Juliana, L

    2015-02-01

    It is scientifically demonstrated that lunar cycles have important effects on several biological events. Controversy exists about the lunar influence on human and animal parturition. In addition, in the horse industry, especially in Polo Horse breeders of Argentina and around the world there is a higher demand for female offspring than for males. The objective of this study was to determine whether there is a significant association between the lunar phase at the time of mating and the sex ratio at birth in horses. The Argentinean Stud Book provided information related to all matings registered for Thoroughbred and Arab horses between 2003 and 2011. Statistical associations were tested between dates of matings at different lunar phases or days and sex ratio at birth. A total of 65.535 gestations were studied. Overall, sex ratio at birth resulted in 33.396 fillies (50.96%) and 32.139 colts (49.04%). The percentages of males and females at birth were not statistically different amongst the different lunar phases or days. We can strongly conclude that managing the breeding dates in relation to lunar cycles in order to manipulate the sex ratio of the offspring is not a viable option in horses.

  10. Abnormal X : autosome ratio, but normal X chromosome inactivation in human triploid cultures

    Directory of Open Access Journals (Sweden)

    Norwood Thomas H

    2006-07-01

    Full Text Available Abstract Background X chromosome inactivation (XCI is that aspect of mammalian dosage compensation that brings about equivalence of X-linked gene expression between females and males by inactivating one of the two X chromosomes (Xi in normal female cells, leaving them with a single active X (Xa as in male cells. In cells with more than two X's, but a diploid autosomal complement, all X's but one, Xa, are inactivated. This phenomenon is commonly thought to suggest 1 that normal development requires a ratio of one Xa per diploid autosomal set, and 2 that an early event in XCI is the marking of one X to be active, with remaining X's becoming inactivated by default. Results Triploids provide a test of these ideas because the ratio of one Xa per diploid autosomal set cannot be achieved, yet this abnormal ratio should not necessarily affect the one-Xa choice mechanism for XCI. Previous studies of XCI patterns in murine triploids support the single-Xa model, but human triploids mostly have two-Xa cells, whether they are XXX or XXY. The XCI patterns we observe in fibroblast cultures from different XXX human triploids suggest that the two-Xa pattern of XCI is selected for, and may have resulted from rare segregation errors or Xi reactivation. Conclusion The initial X inactivation pattern in human triploids, therefore, is likely to resemble the pattern that predominates in murine triploids, i.e., a single Xa, with the remaining X's inactive. Furthermore, our studies of XIST RNA accumulation and promoter methylation suggest that the basic features of XCI are normal in triploids despite the abnormal X:autosome ratio.

  11. Chromosomal characterization of the bonytongue Arapaima gigas (Osteoglossiformes: Arapaimidae

    Directory of Open Access Journals (Sweden)

    Debora Karla Marques

    Full Text Available The mitotic chromosomes of the pirarucu Arapaima gigas inhabiting the middle Araguaia River and collected in the municipality of Araguaiana (MT, Brazil were studied. The chromosomes were analyzed through Giemsa staining, C-banding, Ag-NOR staining and in situ hybridization using an 18S rRNA gene probe. The karyotype had 2n=56 comprising 14 biarmed and 14 uniarmed chromosome pairs in both sexes. No cytologically distinguishable sex chromosome was identified. A single NOR-bearing chromosome pair was detected by Ag-NOR staining and confirmed by 18S rDNA- FISH. Faint constitutive heterochromatin was C-banded in the centromeric region of some chromosomes.

  12. Preconception maternal polychlorinated biphenyl concentrations and the secondary sex ratio

    International Nuclear Information System (INIS)

    Taylor, Kira C.; Jackson, Leila W.; Lynch, Courtney D.; Kostyniak, Paul J.; Buck Louis, Germaine M.

    2007-01-01

    The secondary sex ratio is the ratio of male to female live births and historically has ranged from 102 to 106 males to 100 females. Temporal declines have been reported in many countries prompting authors to hypothesize an environmental etiology. Blood specimens were obtained from 99 women aged 24-34 prior to attempting pregnancy and quantified for 76 polychlorinated biphenyl (PCB) congeners using dual column gas chromatography with electron capture detection. Women were prospectively followed until pregnancy or 12 cycles of trying. The odds of a male birth for three PCB groupings (total, estrogenic, anti-estrogenic) controlling for maternal characteristics were estimated using logistic regression. Among the 50 women with live births and PCB data, 26 female and 24 male infants were born (ratio 0.92). After adjusting for age and body mass index, odds of a male birth were elevated among women in the second (OR=1.29) and third (OR=1.48) tertiles of estrogenic PCBs; odds (OR=0.70) were reduced among women in the highest tertile of anti-estrogenic PCBs. All confidence intervals included one. The direction of the odds ratios in this preliminary study varied by PCB groupings, supporting the need to study specific PCB patterns when assessing environmental influences on the secondary sex ratio

  13. An anther- and petal-specific gene SlMF1 is a multicopy gene with homologous sequences on sex chromosomes

    Czech Academy of Sciences Publication Activity Database

    Matsunaga, S.; Lebel-Hardenack, S.; Kejnovský, Eduard; Vyskot, Boris; Grant, Sarah R.; Kawano, S.

    2005-01-01

    Roč. 80, - (2005), s. 395-401 ISSN 1341-7568 R&D Projects: GA ČR(CZ) GA204/05/2097 Institutional research plan: CEZ:AV0Z50040507 Keywords : dioecious plant * male flower * sex chromosomes Subject RIV: BO - Biophysics Impact factor: 1.081, year: 2005

  14. Ownership of dwelling affects the sex ratio at birth in Uganda.

    Directory of Open Access Journals (Sweden)

    Bernard Wallner

    Full Text Available BACKGROUND: Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH. This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB on a Ugandan sample. METHODOLOGY/PRINCIPAL FINDINGS: Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019 compared to those who live in non-owned dwellings (0.458. Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers' age, mothers' education, parity and others. CONCLUSIONS/SIGNIFICANCE: The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.

  15. Ownership of dwelling affects the sex ratio at birth in Uganda.

    Science.gov (United States)

    Wallner, Bernard; Fieder, Martin; Seidler, Horst

    2012-01-01

    Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH). This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB) on a Ugandan sample. Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019) compared to those who live in non-owned dwellings (0.458). Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers' age, mothers' education, parity and others. The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.

  16. Ownership of Dwelling Affects the Sex Ratio at Birth in Uganda

    Science.gov (United States)

    Wallner, Bernard; Fieder, Martin; Seidler, Horst

    2012-01-01

    Background Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH). This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB) on a Ugandan sample. Methodology/Principal Findings Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019) compared to those who live in non-owned dwellings (0.458). Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers’ age, mothers’ education, parity and others. Conclusions/Significance The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way. PMID:23284697

  17. Sixteen kiwi (Apteryx spp) transcriptomes provide a wealth of genetic markers and insight into sex chromosome evolution in birds.

    Science.gov (United States)

    Ramstad, Kristina M; Miller, Hilary C; Kolle, Gabriel

    2016-05-26

    Kiwi represent the most basal extant avian lineage (paleognaths) and exhibit biological attributes that are unusual or extreme among living birds, such as large egg size, strong olfaction, nocturnality, flightlessness and long lifespan. Despite intense interest in their evolution and their threatened status, genomic resources for kiwi were virtually non-existent until the recent publication of a single genome. Here we present the most comprehensive kiwi transcriptomes to date, obtained via Illumina sequencing of whole blood and de novo assembly of mRNA sequences of eight individuals from each of the two rarest kiwi species, little spotted kiwi (LSK; Apteryx owenii) and rowi (A. rowi). Sequences obtained were orthologous with a wide diversity of functional genes despite the sequencing of a single tissue type. Individual and composite assemblies contain more than 7900 unique protein coding transcripts in each of LSK and rowi that show strong homology with chicken (Gallus gallus), including those associated with growth, development, disease resistance, reproduction and behavior. The assemblies also contain 66,909 SNPs that distinguish between LSK and rowi, 12,384 SNPs among LSK (associated with 3088 genes), and 29,313 SNPs among rowi (associated with 4953 genes). We found 3084 transcripts differentially expressed between LSK and rowi and 150 transcripts differentially expressed between the sexes. Of the latter, 83 could be mapped to chicken chromosomes with 95% syntenic with chromosome Z. Our study has simultaneously sequenced multiple species, sexes, and individual kiwi at thousands of genes, and thus represents a significant leap forward in genomic resources available for kiwi. The expression pattern we observed among chromosome Z related genes in kiwi is similar to that observed in ostriches and emu, suggesting a common and ancestral pattern of sex chromosome homomorphy, recombination, and gene dosage among living paleognaths. The transcriptome assemblies described

  18. Kin discrimination and sex ratios in a parasitoid wasp

    NARCIS (Netherlands)

    Reece, S.E.; Shuker, D.M.; Pen, I.R.; Duncan, A.B.; Choudhary, A.; Batchelor, C.M.; West, S.A.

    Sex ratio theory provides a clear and simple way to test if nonsocial haplodiploid wasps can discriminate between kin and nonkin. Specifically, if females can discriminate siblings from nonrelatives, then they are expected to produce a higher proportion of daughters if they mate with a sibling. This

  19. Thermal fluctuation within nests and predicted sex ratio of Morelet's Crocodile.

    Science.gov (United States)

    Escobedo-Galván, Armando H; López-Luna, Marco A; Cupul-Magaña, Fabio G

    2016-05-01

    Understanding the interplay between thermal variations and sex ratio in reptiles with temperature-dependent sex determination is the first step for developing long-term conservation strategies. In case of crocodilians, the information is fragmentary and insufficient for establishing a general framework to consider how thermal fluctuation influence sex determination under natural conditions. The main goal of this study was to analyze thermal variation in nests of Crocodylus moreletii and to discuss the potential implications for predicting offspring sex ratio. The study was carried out at the Centro de Estudios Tecnológicos del Mar N° 2 and at the Sistemas Productivos Cocodrilo, Campeche, Mexico. Data was collected in the nesting season of Morelet's Crocodiles during three consecutive seasons (2007-2009). Thermal fluctuations for multiple areas of the nest chamber were registered by data loggers. We calculate the constant temperature equivalent based on thermal profiles among nests to assess whether there are differences between the nest temperature and its equivalent to constant temperature. We observed that mean nest temperature was only different among nests, while daily thermal fluctuations vary depending on the depth position within the nest chamber, years and nests. The constant temperature equivalent was different among and within nests, but not among survey years. We observed differences between constant temperature equivalent and mean nest temperature both at the top and in the middle of the nest cavities, but were not significantly different at the bottom of nest cavities. Our results enable examine and discuss the relevance of daily thermal fluctuations to predict sex ratio of the Morelet's Crocodile. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Sex Ratio and Twinning in Women with Hyperemesis or Pre-eclampsia

    DEFF Research Database (Denmark)

    Basso, Olga; Olsen, Jørn

    2001-01-01

    We examined twinning and fetal gender in births of women with a hospital diagnosis of pre-eclampsia or hyperemesis. We also investigated sex ratio in infants whose mothers had had hyperemesis or pre-eclampsia in a different pregnancy. From all the hospitalized cases in Denmark between 1980 and 1996...... we extracted 6,227 births with hyperemesis and 24,764 with pre-eclampsia. Twins were more frequent in pregnancies with either condition. The male to female sex ratio was 1.04 (95%CI = 1.02-1.05) in the reference population, 0.87 (95% CI = 0.82-0.91) in births with hyperemesis, and 1.10 (95% CI = 1...

  1. Human semen quality and the secondary sex ratio.

    Science.gov (United States)

    Bae, Jisuk; Kim, Sungduk; Chen, Zhen; Eisenberg, Michael L; Buck Louis, Germaine M

    2017-01-01

    The aim of this study was to evaluate the association between semen quality and the secondary sex ratio (SSR), defined as the ratio of male to female live births. Our study cohort comprised 227 male partners who were enrolled prior to conception in Michigan and Texas between 2005 and 2009, and prospectively followed through delivery of a singleton birth. The male partners provided a baseline and a follow-up semen sample a month apart. Semen analysis was conducted to assess 27 parameters including five general characteristics, six sperm head measures, 14 morphology measures, and two sperm chromatin stability assay measures. Modified Poisson regression models with a robust error variance were used to estimate the relative risk (RR) and 95% confidence interval (95% CI) of a male birth for each semen parameter, after adjusting for potential confounders. Of the 27 semen parameters, only the percentage of bicephalic sperm was significantly associated with the SSR (2 nd vs 1 st quartile, RR, 0.65, 95% CI, 0.45-0.95, P = 0.03; 4 th vs 1 st quartile, RR, 0.61, 95% CI, 0.38-1.00, P semen quality is associated with offspring sex determination.

  2. Purifying Selection Maintains Dosage-Sensitive Genes during Degeneration of the Threespine Stickleback Y Chromosome

    Science.gov (United States)

    White, Michael A.; Kitano, Jun; Peichel, Catherine L.

    2015-01-01

    Sex chromosomes are subject to unique evolutionary forces that cause suppression of recombination, leading to sequence degeneration and the formation of heteromorphic chromosome pairs (i.e., XY or ZW). Although progress has been made in characterizing the outcomes of these evolutionary processes on vertebrate sex chromosomes, it is still unclear how recombination suppression and sequence divergence typically occur and how gene dosage imbalances are resolved in the heterogametic sex. The threespine stickleback fish (Gasterosteus aculeatus) is a powerful model system to explore vertebrate sex chromosome evolution, as it possesses an XY sex chromosome pair at relatively early stages of differentiation. Using a combination of whole-genome and transcriptome sequencing, we characterized sequence evolution and gene expression across the sex chromosomes. We uncovered two distinct evolutionary strata that correspond with known structural rearrangements on the Y chromosome. In the oldest stratum, only a handful of genes remain, and these genes are under strong purifying selection. By comparing sex-linked gene expression with expression of autosomal orthologs in an outgroup, we show that dosage compensation has not evolved in threespine sticklebacks through upregulation of the X chromosome in males. Instead, in the oldest stratum, the genes that still possess a Y chromosome allele are enriched for genes predicted to be dosage sensitive in mammals and yeast. Our results suggest that dosage imbalances may have been avoided at haploinsufficient genes by retaining function of the Y chromosome allele through strong purifying selection. PMID:25818858

  3. The association between male-biased sex ratio and indicators of stress in red-spotted newts.

    Science.gov (United States)

    Aspbury, Andrea S; Grayson, Kristine L; Fantaye, Selamawit; Nichols, Ian; Myers-Burton, Miranda; Ortiz-Mangual, Xavier; Gabor, Caitlin R

    2017-05-01

    In populations with a male-biased operational sex ratio, coercive mating by males can have fitness consequences for females. One component of reduced fitness for females in populations with a male-biased OSR may be greater activation of the stress response, resulting in higher corticosterone release rates (CORT; a glucocorticoid stress hormone in amphibians). We test the hypothesis that a male-biased sex ratio affects female activity and release rates of CORT and testosterone (T) in male and female red-spotted newts (Notophthalmus viridescens). First, we evaluated if chemical cues from a male-biased sex ratio affect activity and CORT release rates in females. We predicted that females exposed to chemical cues of three males would be less active and have higher CORT release rates than those exposed to chemical cues of one male. Second, we measured CORT release rates of red-spotted newts in field enclosures with either a male-biased or a female-biased sex ratio. We predicted that females in the male-biased treatment would have higher CORT and T release rates than those in a female-biased treatment, owing to higher levels of male harassment. We also predicted that males would have higher CORT and T release rates in male-biased treatments due to higher levels of male-male competition. Females were not less active in response to chemical cues from more males over fewer males, but there was a positive relationship between female activity and CORT when they were exposed to the cues of three males. We also found that females, but not males, in the male-biased sex ratio treatment had higher CORT and T release rates than those in the female-biased treatment. Our results support the hypothesis that a male-biased sex ratio leads to a higher stress response, which may underlie the observed decrease in immune function and body condition in previous work exposing female red-spotted newts to a male-biased sex ratio. This study furthers our understanding of the mechanistic basis

  4. A specific insertion of a solo-LTR characterizes the Y-chromosome of Bryonia dioica (Cucurbitaceae).

    Science.gov (United States)

    Oyama, Ryan K; Silber, Martina V; Renner, Susanne S

    2010-06-14

    Relatively few species of flowering plants are dioecious and even fewer are known to have sex chromosomes. Current theory posits that homomorphic sex chromosomes, such as found in Bryonia dioica (Cucurbitaceae), offer insight into the early stages in the evolution of sex chromosomes from autosomes. Little is known about these early steps, but an accumulation of transposable element sequences has been observed on the Y-chromosomes of some species with heteromorphic sex chromosomes. Recombination, by which transposable elements are removed, is suppressed on at least part of the emerging Y-chromosome, and this may explain the correlation between the emergence of sex chromosomes and transposable element enrichment. We sequenced 2321 bp of the Y-chromosome in Bryonia dioica that flank a male-linked marker, BdY1, reported previously. Within this region, which should be suppressed for recombination, we observed a solo-LTR nested in a Copia-like transposable element. We also found other, presumably paralogous, solo-LTRs in a consensus sequence of the underlying Copia-like transposable element. Given that solo-LTRs arise via recombination events, it is noteworthy that we find one in a genomic region where recombination should be suppressed. Although the solo-LTR could have arisen before recombination was suppressed, creating the male-linked marker BdY1, our previous study on B. dioica suggested that BdY1 may not lie in the recombination-suppressed region of the Y-chromosome in all populations. Presence of a solo-LTR near BdY1 therefore fits with the observed correlation between retrotransposon accumulation and the suppression of recombination early in the evolution of sex chromosomes. These findings further suggest that the homomorphic sex chromosomes of B. dioica, the first organism for which genetic XY sex-determination was inferred, are evolutionarily young and offer reference information for comparative studies of other plant sex chromosomes.

  5. Sex Reversal in Birds.

    Science.gov (United States)

    Major, Andrew T; Smith, Craig A

    2016-01-01

    Sexual differentiation in birds is controlled genetically as in mammals, although the sex chromosomes are different. Males have a ZZ sex chromosome constitution, while females are ZW. Gene(s) on the sex chromosomes must initiate gonadal sex differentiation during embryonic life, inducing paired testes in ZZ individuals and unilateral ovaries in ZW individuals. The traditional view of avian sexual differentiation aligns with that expounded for other vertebrates; upon sexual differentiation, the gonads secrete sex steroid hormones that masculinise or feminise the rest of the body. However, recent studies on naturally occurring or experimentally induced avian sex reversal suggest a significant role for direct genetic factors, in addition to sex hormones, in regulating sexual differentiation of the soma in birds. This review will provide an overview of sex determination in birds and both naturally and experimentally induced sex reversal, with emphasis on the key role of oestrogen. We then consider how recent studies on sex reversal and gynandromorphic birds (half male:half female) are shaping our understanding of sexual differentiation in avians and in vertebrates more broadly. Current evidence shows that sexual differentiation in birds is a mix of direct genetic and hormonal mechanisms. Perturbation of either of these components may lead to sex reversal. © 2016 S. Karger AG, Basel.

  6. Conservation of Sex-Linked Markers among Conspecific Populations of a Viviparous Skink, Niveoscincus ocellatus, Exhibiting Genetic and Temperature-Dependent Sex Determination

    Science.gov (United States)

    Burridge, Christopher P; Ezaz, Tariq; Wapstra, Erik

    2018-01-01

    Abstract Sex determination systems are exceptionally diverse and have undergone multiple and independent evolutionary transitions among species, particularly reptiles. However, the mechanisms underlying these transitions have not been established. Here, we tested for differences in sex-linked markers in the only known reptile that is polymorphic for sex determination system, the spotted snow skink, Niveoscincus ocellatus, to quantify the genomic differences that have accompanied this transition. In a highland population, sex is determined genetically, whereas in a lowland population, offspring sex ratio is influenced by temperature. We found a similar number of sex-linked loci in each population, including shared loci, with genotypes consistent with male heterogamety (XY). However, population-specific linkage disequilibrium suggests greater differentiation of sex chromosomes in the highland population. Our results suggest that transitions between sex determination systems can be facilitated by subtle genetic differences. PMID:29659810

  7. Steroid Hormones and Female Energy Balance: Relation to Offspring Primary Sex Ratio

    NARCIS (Netherlands)

    Aslam, M.L.; Woelders, H.

    2017-01-01

    Birds can manipulate the offspring sex ratio under natural and experimental conditions. Various factors related to the avian mother, as well as her eggs, have been reported to be linked with the sex determination process. These factors appear to affect the chance of laying a male or female egg

  8. A model describing the effect of sex-reversed YY fish in an established wild population: The use of a Trojan Y chromosome to cause extinction of an introduced exotic species.

    Science.gov (United States)

    Gutierrez, Juan B; Teem, John L

    2006-07-21

    A novel means of inducing extinction of an exotic fish population is proposed using a genetic approach to shift the ratio of male to females within a population. In the proposed strategy, sex-reversed fish containing two Y chromosomes are introduced into a normal fish population. These YY fish result in the production of a disproportionate number of male fish in subsequent generations. Mathematical modeling of the system following introduction of YY fish at a constant rate reveals that female fish decline in numbers over time, leading to eventual extinction of the population.

  9. The DNA sequence of the human X chromosome

    Science.gov (United States)

    Ross, Mark T.; Grafham, Darren V.; Coffey, Alison J.; Scherer, Steven; McLay, Kirsten; Muzny, Donna; Platzer, Matthias; Howell, Gareth R.; Burrows, Christine; Bird, Christine P.; Frankish, Adam; Lovell, Frances L.; Howe, Kevin L.; Ashurst, Jennifer L.; Fulton, Robert S.; Sudbrak, Ralf; Wen, Gaiping; Jones, Matthew C.; Hurles, Matthew E.; Andrews, T. Daniel; Scott, Carol E.; Searle, Stephen; Ramser, Juliane; Whittaker, Adam; Deadman, Rebecca; Carter, Nigel P.; Hunt, Sarah E.; Chen, Rui; Cree, Andrew; Gunaratne, Preethi; Havlak, Paul; Hodgson, Anne; Metzker, Michael L.; Richards, Stephen; Scott, Graham; Steffen, David; Sodergren, Erica; Wheeler, David A.; Worley, Kim C.; Ainscough, Rachael; Ambrose, Kerrie D.; Ansari-Lari, M. Ali; Aradhya, Swaroop; Ashwell, Robert I. S.; Babbage, Anne K.; Bagguley, Claire L.; Ballabio, Andrea; Banerjee, Ruby; Barker, Gary E.; Barlow, Karen F.; Barrett, Ian P.; Bates, Karen N.; Beare, David M.; Beasley, Helen; Beasley, Oliver; Beck, Alfred; Bethel, Graeme; Blechschmidt, Karin; Brady, Nicola; Bray-Allen, Sarah; Bridgeman, Anne M.; Brown, Andrew J.; Brown, Mary J.; Bonnin, David; Bruford, Elspeth A.; Buhay, Christian; Burch, Paula; Burford, Deborah; Burgess, Joanne; Burrill, Wayne; Burton, John; Bye, Jackie M.; Carder, Carol; Carrel, Laura; Chako, Joseph; Chapman, Joanne C.; Chavez, Dean; Chen, Ellson; Chen, Guan; Chen, Yuan; Chen, Zhijian; Chinault, Craig; Ciccodicola, Alfredo; Clark, Sue Y.; Clarke, Graham; Clee, Chris M.; Clegg, Sheila; Clerc-Blankenburg, Kerstin; Clifford, Karen; Cobley, Vicky; Cole, Charlotte G.; Conquer, Jen S.; Corby, Nicole; Connor, Richard E.; David, Robert; Davies, Joy; Davis, Clay; Davis, John; Delgado, Oliver; DeShazo, Denise; Dhami, Pawandeep; Ding, Yan; Dinh, Huyen; Dodsworth, Steve; Draper, Heather; Dugan-Rocha, Shannon; Dunham, Andrew; Dunn, Matthew; Durbin, K. James; Dutta, Ireena; Eades, Tamsin; Ellwood, Matthew; Emery-Cohen, Alexandra; Errington, Helen; Evans, Kathryn L.; Faulkner, Louisa; Francis, Fiona; Frankland, John; Fraser, Audrey E.; Galgoczy, Petra; Gilbert, James; Gill, Rachel; Glöckner, Gernot; Gregory, Simon G.; Gribble, Susan; Griffiths, Coline; Grocock, Russell; Gu, Yanghong; Gwilliam, Rhian; Hamilton, Cerissa; Hart, Elizabeth A.; Hawes, Alicia; Heath, Paul D.; Heitmann, Katja; Hennig, Steffen; Hernandez, Judith; Hinzmann, Bernd; Ho, Sarah; Hoffs, Michael; Howden, Phillip J.; Huckle, Elizabeth J.; Hume, Jennifer; Hunt, Paul J.; Hunt, Adrienne R.; Isherwood, Judith; Jacob, Leni; Johnson, David; Jones, Sally; de Jong, Pieter J.; Joseph, Shirin S.; Keenan, Stephen; Kelly, Susan; Kershaw, Joanne K.; Khan, Ziad; Kioschis, Petra; Klages, Sven; Knights, Andrew J.; Kosiura, Anna; Kovar-Smith, Christie; Laird, Gavin K.; Langford, Cordelia; Lawlor, Stephanie; Leversha, Margaret; Lewis, Lora; Liu, Wen; Lloyd, Christine; Lloyd, David M.; Loulseged, Hermela; Loveland, Jane E.; Lovell, Jamieson D.; Lozado, Ryan; Lu, Jing; Lyne, Rachael; Ma, Jie; Maheshwari, Manjula; Matthews, Lucy H.; McDowall, Jennifer; McLaren, Stuart; McMurray, Amanda; Meidl, Patrick; Meitinger, Thomas; Milne, Sarah; Miner, George; Mistry, Shailesh L.; Morgan, Margaret; Morris, Sidney; Müller, Ines; Mullikin, James C.; Nguyen, Ngoc; Nordsiek, Gabriele; Nyakatura, Gerald; O’Dell, Christopher N.; Okwuonu, Geoffery; Palmer, Sophie; Pandian, Richard; Parker, David; Parrish, Julia; Pasternak, Shiran; Patel, Dina; Pearce, Alex V.; Pearson, Danita M.; Pelan, Sarah E.; Perez, Lesette; Porter, Keith M.; Ramsey, Yvonne; Reichwald, Kathrin; Rhodes, Susan; Ridler, Kerry A.; Schlessinger, David; Schueler, Mary G.; Sehra, Harminder K.; Shaw-Smith, Charles; Shen, Hua; Sheridan, Elizabeth M.; Shownkeen, Ratna; Skuce, Carl D.; Smith, Michelle L.; Sotheran, Elizabeth C.; Steingruber, Helen E.; Steward, Charles A.; Storey, Roy; Swann, R. Mark; Swarbreck, David; Tabor, Paul E.; Taudien, Stefan; Taylor, Tineace; Teague, Brian; Thomas, Karen; Thorpe, Andrea; Timms, Kirsten; Tracey, Alan; Trevanion, Steve; Tromans, Anthony C.; d’Urso, Michele; Verduzco, Daniel; Villasana, Donna; Waldron, Lenee; Wall, Melanie; Wang, Qiaoyan; Warren, James; Warry, Georgina L.; Wei, Xuehong; West, Anthony; Whitehead, Siobhan L.; Whiteley, Mathew N.; Wilkinson, Jane E.; Willey, David L.; Williams, Gabrielle; Williams, Leanne; Williamson, Angela; Williamson, Helen; Wilming, Laurens; Woodmansey, Rebecca L.; Wray, Paul W.; Yen, Jennifer; Zhang, Jingkun; Zhou, Jianling; Zoghbi, Huda; Zorilla, Sara; Buck, David; Reinhardt, Richard; Poustka, Annemarie; Rosenthal, André; Lehrach, Hans; Meindl, Alfons; Minx, Patrick J.; Hillier, LaDeana W.; Willard, Huntington F.; Wilson, Richard K.; Waterston, Robert H.; Rice, Catherine M.; Vaudin, Mark; Coulson, Alan; Nelson, David L.; Weinstock, George; Sulston, John E.; Durbin, Richard; Hubbard, Tim; Gibbs, Richard A.; Beck, Stephan; Rogers, Jane; Bentley, David R.

    2009-01-01

    The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence. PMID:15772651

  10. Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio.

    Directory of Open Access Journals (Sweden)

    João Fabrício Mota Rodrigues

    Full Text Available Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population's sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

  11. Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio.

    Science.gov (United States)

    Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco

    2016-01-01

    Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population's sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

  12. Sex ratio of lambs born from assisted reproductive technologies ...

    African Journals Online (AJOL)

    The objective of the present study was to investigate sex ratio of offspring resulting from superstimulated donors from two different breeds and artificially inseminated ewes from three different breeds. Romanov (n = 5) and Charollais (n = 6) (2 - 7 years of age) donors were superovulated using FSH-p with 400 mg ...

  13. A rearrangement of the Z chromosome topology influences the sex-linked gene display in the European corn borer, Ostrinia nubilalis

    Science.gov (United States)

    The sex determination system of Lepidoptera is comprised of heterogametic females (ZW) and homogametic males (ZZ), where voltinism (Volt) and the male pheromone response traits (Resp) are controlled by genes housed on the Z-chromosome. Volt and Resp determine traits that lead to ecotype differentia...

  14. Sex ratio and time to pregnancy: analysis of four large European population surveys

    DEFF Research Database (Denmark)

    Joffe, Mike; Bennett, James; Best, Nicky

    2007-01-01

    To test whether the secondary sex ratio (proportion of male births) is associated with time to pregnancy, a marker of fertility. Design Analysis of four large population surveys. Setting Denmark and the United Kingdom. Participants 49 506 pregnancies.......To test whether the secondary sex ratio (proportion of male births) is associated with time to pregnancy, a marker of fertility. Design Analysis of four large population surveys. Setting Denmark and the United Kingdom. Participants 49 506 pregnancies....

  15. Resolution and evolution of the duck-billed platypus karyotype with an X1Y1X2Y2X3Y3X4Y4X5Y5 male sex chromosome constitution.

    Science.gov (United States)

    Rens, Willem; Grützner, Frank; O'brien, Patricia C M; Fairclough, Helen; Graves, Jennifer A M; Ferguson-Smith, Malcolm A

    2004-11-16

    The platypus (2n = 52) has a complex karyotype that has been controversial over the last three decades. The presence of unpaired chromosomes and an unknown sex-determining system especially has defied attempts at conventional analysis. This article reports on the preparation of chromosome-specific probes from flow-sorted chromosomes and their application in the identification and classification of all platypus chromosomes. This work reveals that the male karyotype has 21 pairs of chromosomes and 10 unpaired chromosomes (E1-E10), which are linked by short regions of homology to form a multivalent chain in meiosis. The female karyotype differs in that five of these unpaired elements (E1, E3, E5, E7, and E9) are each present in duplicate, whereas the remaining five unpaired elements (E2, E4, E6, E8, and E10) are absent. This finding indicates that sex is determined by the alternate segregation of the chain of 10 during spermatogenesis so that equal numbers of sperm bear either one of the two groups of five elements, i.e., five X and five Y chromosomes. Chromosome painting reveals that these X and Y chromosomes contain pairing (XY shared) and differential (X- or Y-specific) segments. Y differential regions must contain male-determining genes, and X differential regions should be dosage-compensated in the female. Two models for the evolution of the sex-determining system are presented. The resolution of the longstanding debate over the platypus karyotype is an important step toward the understanding of mechanisms of sex determination, dosage compensation, and karyotype evolution.

  16. The Relationship of Body Length and Ratio Pappilla with Sex in Gobi Fish (Sicyopterus macrostetholepis

    Directory of Open Access Journals (Sweden)

    Rona Taula Sari

    2017-07-01

    Full Text Available Research about the relationship of body length and ratio papilla with sex in goby fish (S. macrostetholepis Blkr. has been done at Animal Structure and Developmental Laboratory, Biologi Department, Faculty of Matematics and Natural Sciences, Andalas University, Padang, which purposed to analyse the relationship of body length and ratio papilla with sex of goby fish (S. macrostetholepis Blkr.. The samples were taken in wild stream area at Batangkuranji river, Padang City. This research used descriptive method and data were analyzed by qualitatively and quantitatively. The results of investigation showed that in several goby fishes (S. macrostetholepis Blkr. with different sex had the same of body length and the same of ratio papilla. So, there was not relationship between of body length and ratio papilla with sex.  Goby fishes (S. macrostetholepis Blkr. it belongs to the hermaphrodite protogini, which the androgynous young females, while in adulthood, it would change sex to male. The results of this study are expected to add to the treasures of knowledge and information about reproductive gobies (S. macrostetholepis Blkr. in the preservation and development of fish farming.   

  17. Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

    DEFF Research Database (Denmark)

    Timmermann, Clara Amalie Gade; Choi, Anna L; Petersen, Maria Skaalum

    2017-01-01

    This study was undertaken to assess the potential impact of maternal exposures to polychlorinated biphenyl (PCB), dichlorodiphenyl dichloroethylene (DDE) and methylmercury on the secondary sex ratios (the ratio of male to female live births) over a span of 23 years. The study includes prospective......% CI = 2-17%), respectively, of giving birth to a boy. In conclusion, maternal exposure to ΣPCB, DDE and methylmercury was associated with a slightly increased secondary sex ratio. The impact of paternal exposures could not be taken into account and deserves attention....

  18. Variation in offspring sex ratio of a long-lived sexually dimorphic raptor, the eastern imperial eagle (Aquila heliaca)

    Science.gov (United States)

    Todd E. Katzner; Daniel S. Jackson; Jamie Ivy; Evgeny A. Bragin; Andrew Dewoody

    2014-01-01

    Sex ratio theory attempts to explain observed variation in offspring sex ratio at both the population and the brood levels. In the context of low-fecundity organisms producing high-investment offspring, the drivers of adaptive variation in sex ratio are incompletely understood. For raptors that display reverse sexual dimorphism (RSD), preferential allocation of...

  19. Step-by-step evolution of neo-sex chromosomes in geographical populations of wild silkmoths, Samia cynthia ssp

    Czech Academy of Sciences Publication Activity Database

    Yoshido, A.; Sahara, K.; Marec, František; Matsuda, Y.

    2011-01-01

    Roč. 106, č. 4 (2011), s. 614-624 ISSN 0018-067X R&D Projects: GA AV ČR IAA600960925 Grant - others:Japan Society for the Promotion of Science(JP) 19-1114; Japan Society for the Promotion of Science(JP) 21-7147 Institutional research plan: CEZ:AV0Z50070508 Keywords : Lepidoptera * sex chromosomes * fluorescences Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.597, year: 2011

  20. SEASONAL-VARIATION IN THE SEX-RATIO OF MARSH HARRIER CIRCUS-AERUGINOSUS BROODS

    NARCIS (Netherlands)

    ZIJLSTRA, M; DAAN, S; BRUINENBERGRINSMA, J

    1992-01-01

    1. Analysis of the sexes of 2260 nestlings in 735 marsh harrier broods revealed an overall excess [sex ratio (SR) = 54.8%] of males, and a significant increase in the proportion of males with progressive laying date (d = day of the year): In [SR/(1-SR)] = -1.286 + 0.013 d. 2. We argue that it is

  1. Tissue- and stage-dependent dosage compensation on the Neo-X chromosome in drosophila pseudoobscura

    KAUST Repository

    Nozawa, Masafumi; Fukuda, Nana; Ikeo, Kazuho; Gojobori, Takashi

    2013-01-01

    Sex chromosome dosage compensation (DC) is widely accepted in various organisms. This concept is mostly supported by comparisons of gene expression between chromosomes and between sexes. However, genes on the X chromosome and autosomes are mostly

  2. Sibling Sex Ratio and Birth Order in Early-Onset Gender Dysphoric Adolescents

    NARCIS (Netherlands)

    Schagen, S.E.E.; Delemarre-van de Waal, H.A.; Blanchard, R.; Cohen-Kettenis, P.T.

    2012-01-01

    Several sibship-related variables have been studied extensively in sexual orientation research, especially in men. Sibling sex ratio refers to the ratio of brothers to sisters in the aggregate sibships of a group of probands. Birth order refers to the probands' position (e.g., first-born,

  3. Effect of Temperature on Reproduction and Sex Ratio of Guppy (Poecilia reticulata Peters)

    OpenAIRE

    H. Arfah; S. Mariam; . Alimuddin

    2007-01-01

    Water temperature could affect the reproduction of broodstock and sex ratio of progeny.  In this study, broodstock of guppy (Poecilia reticulata Peters) was reared in different temperature to determine its effect on reproduction of broodstock and sex ratio of their progeny. The result of study show that broodstock reared at 27°C produced more fry (16 males mean) than that of 30°C (10 males), while broodstock reared at 33°C produced no progeny.  Percentage of male fish produced by broodstock r...

  4. [Paternal exposure to occupational electromagnetic radiation and sex ratio of the offspring: a meta-analysis].

    Science.gov (United States)

    Tong, Shu-Hui; Liu, Yi-Ting; Liu, Yang

    2013-02-01

    To investigate the association between paternal exposure to occupational electromagnetic radiation and the sex ratio of the offspring. We searched various databases, including PubMed, Embase, Cochrane Library, OVID, Bioscience Information Service (BIOSIS), China National Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals and Wanfang Database, for the literature relevant to the association of paternal exposure to occupational electromagnetic radiation with the sex ratio of the offspring. We conducted a meta-analysis on their correlation using Stata 11.0. There was no statistically significant difference in the sex ratio between the offspring with paternal exposure to occupational electromagnetic radiation and those without (pooled OR = 1.00 [95% CI: 0.95 -1.05], P = 0.875). Subgroup analysis of both case-control and cohort studies revealed no significant difference (pooled OR = 1.03 [95% CI: 0.99 -1.08], P = 0.104 and pooled OR = 0.98 [95% CI: 0.99 -1.08], P = 0.186, respectively). Paternal exposure to occupational electromagnetic radiation is not correlated with the sex ratio of the offspring.

  5. Identification of 2nd chromosome region translocated onto the W chromosome by RFLP with EST-cDNA clones in the Gensei-kouken strains of the mulberry silkworm, Bombyx mori L

    Directory of Open Access Journals (Sweden)

    Sivaramakurup Sreekumar

    2010-01-01

    Full Text Available In silkworms, sex-limited strains are either obtained spontaneously or induced by X-rays or gamma rays. When a fragment of an autosome carrying a dominant allele of those genes responsible for certain characters is translocated onto a W chromosome, the female of the successive generations will express these phenotypic characters and sex discrimination can be facilitated. Gensei-kouken strains are sex-limited strains of silkworms developed by irradiating the pupae with gamma rays, by which a portion of the second chromosome is translocated onto the W chromosome. In these improved strains, the females are yellow-blooded and spin yellow cocoons. By using the EST-cDNA clones mapped on the Z chromosome, we identified the sex according to the polymorphic banding pattern or intensity of the signals. Furthermore, by using the clones on the second chromosome, the region of the second chromosome translocated onto the W chromosome was also defined. In both the A95 and A 96 strains selected for the present study, only the mid-portion of the second chromosome was translocated. The differences in length of the fragments translocated in these strains are discussed.

  6. Maternal Eating Disorders Influence Sex Ratio at Birth

    OpenAIRE

    Bulik, Cynthia M; Von Holle, Ann; Gendall, Kelly; Kveim Lie, Kari; Hoffman, Elizabeth; Mo, Xiaofei; Torgersen, Leila; Reichborn-Kjennerud, Ted

    2008-01-01

    We explored sex ratio at birth, defined as the proportion of male live births, in women with anorexia nervosa, bulimia nervosa, binge eating disorder, and eating disorders not otherwise specified-purging type (EDNOS-P) relative to a referent group in a large population based sample of 38,340 pregnant women in Norway. Poisson regressions were adjusted for mother’s age, pre-pregnancy BMI, lifetime smoking status, maternal education, income, marital status, gestational age, and parity. Lower pro...

  7. Sex ratios, mating frequencies and relative abundance of sympatric millipedes in the genus Chersastus (Diplopoda: Pachybolidae

    Directory of Open Access Journals (Sweden)

    Mark Ian Cooper

    2014-12-01

    Full Text Available Three hypotheses exist for explaining climbing behavior in millipedes: 1 waterlogging, 2 detritus limiting, and 3 mate avoidance. Data of sex ratios, mating frequency and relative abundance are provided to suggest an alternative explanation for the pattern in sympatric forest millipedes. Sex ratio differences - from equality - were tested using a G-test comparing millipedes on and above ground. Mating frequencies were calculated based on the percentage of paired individuals. Relative abundance may correlate with male-biases in the sex ratios. All three factors suggest Chersastus inscriptus has a higher reproductive potential than C. anulatus. This is evidence for mating hotspots.

  8. Causes and consequences of adult sex ratio imbalance in a historical U.S. population.

    Science.gov (United States)

    Schacht, Ryan; Smith, Ken R

    2017-09-19

    The responsiveness of individuals to partner availability has been well-documented across the literature. However, there is disagreement regarding the direction of the consequences of sex ratio imbalance. Specifically, does an excess of males or females promote male-male mating competition? In an attempt to clarify the role of the adult sex ratio (ASR) on behaviour, here we evaluate both competing and complimentary expectations derived from theory across the social and biological sciences. We use data drawn from a historical, nineteenth century population in North America and target several life-history traits thought to be affected by partner availability: age at first birth, relationship status, completed fertility and longevity. Furthermore, we assess the role of various contributors to a population's ASR. We find that both the contributors to and consequences of sex ratio imbalance vary over time. Our results largely support predictions of greater male pairbond commitment and lesser male mating effort, as well as elevated bargaining power of women in response to female scarcity. After reviewing our findings, and others from across the literature, we highlight the need to adjust predictions in response to ASR imbalance by the: (i) culturally mediated mating arena, (ii) variable role of demographic inputs across time and place, (iii) constraints to behavioural outcomes across populations, and (iv) ability and accuracy of individuals to assess partner availability.This article is part of the themed issue 'Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

  9. Accelerated pseudogenization on the neo-X chromosome in Drosophila miranda

    KAUST Repository

    Nozawa, Masafumi; Onizuka, Kanako; Fujimi, Mai; Ikeo, Kazuho; Gojobori, Takashi

    2016-01-01

    Y chromosomes often degenerate via the accumulation of pseudogenes and transposable elements. By contrast, little is known about X-chromosome degeneration. Here we compare the pseudogenization process between genes on the neo-sex chromosomes

  10. Female starlings adjust primary sex ratio in response to aromatic plants in the nest.

    Science.gov (United States)

    Polo, Vicente; Veiga, José P; Cordero, Pedro J; Viñuela, Javier; Monaghan, Pat

    2004-09-22

    Adjustment of offspring sex ratios should be favoured by natural selection when parents are capable of facultatively altering brood sex ratios and of recognizing the circumstances that predict the probable fitness benefit of producing sons and daughters. Although experimental studies have shown that female birds may adjust offspring sex ratios in response to changes in their own condition and in the external appearance of their mate, and male attributes other than his external morphology are also thought to act as signals of male quality, it is not known whether females will respond to changes in such signals, in the absence of any change in the appearance of the male himself. Here, we experimentally manipulated a male courtship display, the green plants carried to the nest by male spotless starlings (Sturnus unicolor), without changing any physical attributes of the male himself, and examined whether this influenced female decisions on offspring sex ratio. We found that in an environment in which female starlings were producing more daughters than sons, experimental enhancement of the green nesting material caused females to significantly increase the number of male eggs produced and thereby removed the female bias. This effect was consistent in 2 years and at two localities. This demonstrates that the green material, whose function has long puzzled biologists, conveys important information to the female and that she facultatively adjusts offspring production accordingly.

  11. The effect of climate fluctuation on chimpanzee birth sex ratio.

    Directory of Open Access Journals (Sweden)

    Hjalmar S Kühl

    Full Text Available Climate and weather conditions, such as the North Atlantic Oscillation, precipitation and temperature influence the birth sex ratio (BSR of various higher latitude species, including deer, elephant seals or northern human populations. Although, tropical regions show only little variation in temperature, climate and weather conditions can fluctuate with consequences for phenology and food resource availability. Here, we evaluate, whether the BSR of chimpanzees, inhabiting African tropical forests, is affected by climate fluctuations as well. Additionally, we evaluate, if variation in consumption of a key food resource with high nutritional value, Coula edulis nuts, is linked to both climate fluctuations and variation in BSR. We use long-term data from two study groups located in Taï National Park, Côte d'Ivoire to assess the influence of local weather conditions and the global climate driver El Niño Southern Oscillation (ENSO on offspring sex. Côte d'Ivoire has experienced considerable climate variation over the last decades, with increasing temperature and declining precipitation. For both groups we find very similar time windows around the month of conception, in which offspring sex is well predicted by ENSO, with more males following low ENSO values, corresponding to periods of high rainfall. Furthermore, we find that the time spent cracking and feeding on Coula nuts is strongly influenced by climate conditions. Although, some of our analysis suggest that a higher proportion of males is born after periods with higher nut consumption frequency, we cannot conclude decisively at this point that nut consumption may influence shifts in BSR. All results combined suggest that also chimpanzees may experience climate related shifts in offspring sex ratios as response to climate fluctuation.

  12. The ZW sex microchromosomes of an Australian dragon lizard share no homology with those of other reptiles or birds.

    Science.gov (United States)

    Ezaz, Tariq; Moritz, Benjamin; Waters, Paul; Marshall Graves, Jennifer A; Georges, Arthur; Sarre, Stephen D

    2009-01-01

    Reptiles show a diverse array of sex chromosomal systems but, remarkably, the Z sex chromosomes of chicken are homologous to the ZW sex chromosomes of a species of gecko, Gekko hokouensis, suggesting an ancient but common origin. This is in contrast to the ZW sex chromosomes of snakes and a species of soft-shelled turtle, Pelodiscus sinensis, which are nonhomologous to those of chicken or each other and appear to have been independently derived. In this paper, we determine what homology, if any, the sex chromosomes of the Australian dragon lizard Pogona vitticeps shares with those of snake and chicken by mapping the dragon homologs of five snake Z chromosome genes (WAC, KLF6, TAX1BP1, RAB5A, and CTNNB1) and five chicken Z chromosome genes (ATP5A1, GHR, DMRT1, CHD1, and APTX) to chromosomes in the dragon. The dragon homologs of snake and chicken sex chromosome genes map to chromosomes 6 and chromosome 2, respectively, in the dragon and that DMRT1, the bird sex-determining gene, is not located on the sex chromosomes of P. vitticeps. Indeed, our data show that the dragon homolog to the chicken Z chromosome is likely to be wholly contained within chromosome 2 in P. vitticeps, which suggests that the sex-determining factor in P. vitticeps is not the sex-determining gene of chicken. Homology between chicken Z chromosome and G. hokouensis ZW chromosome pairs has been interpreted as retention of ancient ZW sex chromosomes in which case the nonhomologous sex chromosomes of snake and dragons would be independently derived. Our data add another case of independently derived sex chromosomes in a squamate reptile, which makes retention of ancient sex chromosome homology in the squamates less plausible. Alternatively, the conservation between the bird Z chromosome and the G. hokouensis ZW chromosomes pairs is coincidental, may be an example of convergent evolution, its status as the Z chromosome having been independently derived in birds and G. hokouensis.

  13. Maintenance of polygenic sex determination in a fluctuating environment: an individual-based model.

    Science.gov (United States)

    Bateman, A W; Anholt, B R

    2017-05-01

    R. A. Fisher predicted that individuals should invest equally in offspring of both sexes, and that the proportion of males and females produced (the primary sex ratio) should evolve towards 1:1 when unconstrained. For many species, sex determination is dependent on sex chromosomes, creating a strong tendency for balanced sex ratios, but in other cases, multiple autosomal genes interact to determine sex. In such cases, the maintenance of multiple sex-determining alleles at multiple loci and the consequent among-family variability in sex ratios presents a puzzle, as theory predicts that such systems should be unstable. Theory also predicts that environmental influences on sex can complicate outcomes of genetic sex determination, and that population structure may play a role. Tigriopus californicus, a copepod that lives in splash-pool metapopulations and exhibits polygenic and environment-dependent sex determination, presents a test case for relevant theory. We use this species as a model for parameterizing an individual-based simulation to investigate conditions that could maintain polygenic sex determination. We find that metapopulation structure can delay the degradation of polygenic sex determination and that periods of alternating frequency-dependent selection, imposed by seasonal fluctuations in environmental conditions, can maintain polygenic sex determination indefinitely. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  14. The genomics of plant sex chromosomes

    Czech Academy of Sciences Publication Activity Database

    Vyskot, Boris; Hobza, Roman

    2015-01-01

    Roč. 236, JUL 2015 (2015), s. 126-135 ISSN 0168-9452 R&D Projects: GA ČR(CZ) GBP501/12/G090; GA ČR(CZ) GAP501/12/2220 Institutional support: RVO:68081707 Keywords : Y-CHROMOSOME * SILENE-LATIFOLIA * DIOECIOUS PLANT Subject RIV: BO - Biophysics Impact factor: 3.362, year: 2015

  15. Somatic sex-specific transcriptome differences in Drosophila revealed by whole transcriptome sequencing

    Directory of Open Access Journals (Sweden)

    Arbeitman Michelle N

    2011-07-01

    Full Text Available Abstract Background Understanding animal development and physiology at a molecular-biological level has been advanced by the ability to determine at high resolution the repertoire of mRNA molecules by whole transcriptome resequencing. This includes the ability to detect and quantify rare abundance transcripts and isoform-specific mRNA variants produced from a gene. The sex hierarchy consists of a pre-mRNA splicing cascade that directs the production of sex-specific transcription factors that specify nearly all sexual dimorphism. We have used deep RNA sequencing to gain insight into how the Drosophila sex hierarchy generates somatic sex differences, by examining gene and transcript isoform expression differences between the sexes in adult head tissues. Results Here we find 1,381 genes that differ in overall expression levels and 1,370 isoform-specific transcripts that differ between males and females. Additionally, we find 512 genes not regulated downstream of transformer that are significantly more highly expressed in males than females. These 512 genes are enriched on the × chromosome and reside adjacent to dosage compensation complex entry sites, which taken together suggests that their residence on the × chromosome might be sufficient to confer male-biased expression. There are no transcription unit structural features, from a set of features, that are robustly significantly different in the genes with significant sex differences in the ratio of isoform-specific transcripts, as compared to random isoform-specific transcripts, suggesting that there is no single molecular mechanism that generates isoform-specific transcript differences between the sexes, even though the sex hierarchy is known to include three pre-mRNA splicing factors. Conclusions We identify thousands of genes that show sex-specific differences in overall gene expression levels, and identify hundreds of additional genes that have differences in the abundance of isoform

  16. Flow cytometric sexing of spider sperm reveals an equal sperm production ratio in a female-biased species

    DEFF Research Database (Denmark)

    Vanthournout, Bram; Deswarte, K; Hammad, H

    2014-01-01

    research. Pinpointing the underlying mechanism of sex ratio bias is challenging owing to the multitude of potential sex ratio-biasing factors. In the dwarf spider, Oedothorax gibbosus, infection with the bacterial endosymbiont Wolbachia results in a female bias. However, pedigree analysis reveals...

  17. Comparative Genomic Hybridization (CGH) reveals a neo-X chromosome and biased gene movement in stalk-eyed flies (genus Teleopsis).

    Science.gov (United States)

    Baker, Richard H; Wilkinson, Gerald S

    2010-09-16

    Chromosomal location has a significant effect on the evolutionary dynamics of genes involved in sexual dimorphism, impacting both the pattern of sex-specific gene expression and the rate of duplication and protein evolution for these genes. For nearly all non-model organisms, however, knowledge of chromosomal gene content is minimal and difficult to obtain on a genomic scale. In this study, we utilized Comparative Genomic Hybridization (CGH), using probes designed from EST sequence, to identify genes located on the X chromosome of four species in the stalk-eyed fly genus Teleopsis. Analysis of log(2) ratio values of female-to-male hybridization intensities from the CGH microarrays for over 3,400 genes reveals a strongly bimodal distribution that clearly differentiates autosomal from X-linked genes for all four species. Genotyping of 33 and linkage mapping of 28 of these genes in Teleopsis dalmanni indicate the CGH results correctly identified chromosomal location in all cases. Syntenic comparison with Drosophila indicates that 90% of the X-linked genes in Teleopsis are homologous to genes located on chromosome 2L in Drosophila melanogaster, suggesting the formation of a nearly complete neo-X chromosome from Muller element B in the dipteran lineage leading to Teleopsis. Analysis of gene movement both relative to Drosophila and within Teleopsis indicates that gene movement is significantly associated with 1) rates of protein evolution, 2) the pattern of gene duplication, and 3) the evolution of eyespan sexual dimorphism. Overall, this study reveals that diopsids are a critical group for understanding the evolution of sex chromosomes within Diptera. In addition, we demonstrate that CGH is a useful technique for identifying chromosomal sex-linkage and should be applicable to other organisms with EST or partial genomic information.

  18. Comparative Genomic Hybridization (CGH reveals a neo-X chromosome and biased gene movement in stalk-eyed flies (genus Teleopsis.

    Directory of Open Access Journals (Sweden)

    Richard H Baker

    2010-09-01

    Full Text Available Chromosomal location has a significant effect on the evolutionary dynamics of genes involved in sexual dimorphism, impacting both the pattern of sex-specific gene expression and the rate of duplication and protein evolution for these genes. For nearly all non-model organisms, however, knowledge of chromosomal gene content is minimal and difficult to obtain on a genomic scale. In this study, we utilized Comparative Genomic Hybridization (CGH, using probes designed from EST sequence, to identify genes located on the X chromosome of four species in the stalk-eyed fly genus Teleopsis. Analysis of log(2 ratio values of female-to-male hybridization intensities from the CGH microarrays for over 3,400 genes reveals a strongly bimodal distribution that clearly differentiates autosomal from X-linked genes for all four species. Genotyping of 33 and linkage mapping of 28 of these genes in Teleopsis dalmanni indicate the CGH results correctly identified chromosomal location in all cases. Syntenic comparison with Drosophila indicates that 90% of the X-linked genes in Teleopsis are homologous to genes located on chromosome 2L in Drosophila melanogaster, suggesting the formation of a nearly complete neo-X chromosome from Muller element B in the dipteran lineage leading to Teleopsis. Analysis of gene movement both relative to Drosophila and within Teleopsis indicates that gene movement is significantly associated with 1 rates of protein evolution, 2 the pattern of gene duplication, and 3 the evolution of eyespan sexual dimorphism. Overall, this study reveals that diopsids are a critical group for understanding the evolution of sex chromosomes within Diptera. In addition, we demonstrate that CGH is a useful technique for identifying chromosomal sex-linkage and should be applicable to other organisms with EST or partial genomic information.

  19. The Sex Ratio of Full and Half Siblings of People Diagnosed With ADHD in Childhood and Adolescence

    DEFF Research Database (Denmark)

    Mouridsen, Svend Erik Birkebæk; Rich, Bente; Isager, Torben

    2014-01-01

    Objective:It has been suggested that high levels of prenatal testosterone exposure are implied in the etiology of male preponderance disorders such as autism spectrum disorder and ADHD. Within this scope, we studied the sex ratio (proportion of males) in siblings of individuals diagnosed with ADHD...... in childhood and adolescence. Method: We did a nationwide, register-based cohort study of the sex ratio in siblings of the 16,381 patients in Denmark diagnosed with ADHD at age 17 years and younger and registered in the nationwide Danish Psychiatric Central Register between January 1, 1994 and May 28, 2013....... Results: Among the 33,151 siblings, 17,041 were males and 16,110 females. This yields a sex ratio of 0.514, which is not statistically significant different from the Danish live birth sex ratio of 0.513 during the relevant years (p = .70). Conclusion: These findings provide no support for the hypothesis...

  20. Sex ratio of five species of pelagic copepods from Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswathy, M.; Santhakumari, V.

    Sex ratio in five species from south and southeast coast of India varied remarkably. Five species were selected for the present investigation. Range in the percentage of males was from 8 to 121 in @iUndinula vulgaris@@ (Dana), 16-425 in @i...

  1. Explaining the Rapid Increase in Nigeria's Sex Ratio at Birth: Factors and Implications.

    Science.gov (United States)

    Kaba, Amadu J

    2015-06-01

    This paper examines the rapid increase in Nigeria's sex ratio at birth from 1.03 boys born for every 1 girl born in each year from 1996-2008 to 1.06 in each year from 2009-2014, second only to Tunisia in Africa at 1.07. The average sex ratio at birth in the world in 2014 was 1.07. In most Black African nations or Black majority nations, it is 1.03 or less. Among the factors presented for this development are: historical fluctuations of sex ratio at birth; geography and ethnicity; male preference/chasing a son; Age of parents; high death rates of male infants and males in general; and wealth/socioeconomic status. Among the potential implications are: young and poor men in Nigeria may not be able to find brides and form families due to a potential shortage of females; emigration of young and poor Nigerian men to West (Africa) and elsewhere to seek brides and form families; immigration of marriage age women from West (Africa) and around the world to Nigeria to seek husbands; and low contraceptive use and high fertility rates in Nigeria.

  2. Chromosomes and their meiotic behaviour in two species of Dieuches Dohrn, 1860 (Heteroptera: Lygaeidae: Rhyparochromini

    Directory of Open Access Journals (Sweden)

    Harbhajan Kaur

    2009-08-01

    Full Text Available The Lygaeidae (Heteroptera are a large and diverse family in which the male diploid chromosomal complement ranges from 10 to 30. Diploid numbers of 14 and 16 are taken as two modal numbers of the family. The Rhyparochrominae, one of the largest subfamilies of the Lygaeidae, are known to be heterogeneous both cytologically and morphologically. Available data on the tribe Rhyparochromini reveal that all species are characterized by the presence of a pair of microchromosomes (m-chromosomes and have an XY/XX (♂/♀ sex chromosome determining system. Dieuches coloratus (Distant, 1909 and D. insignis (Distant, 1918 belonging to Rhyparochromini, have 2n=14=10A+2m+XY and 2n=12=8A+2m+XY respectively. Both the species are similar inone pair of distinctly large autosomes in their chromosome complements. The metaphase plate arrangement of autosomes, sex chromosomes and m-chromosomes in D. coloratus is similar to the common condition observed in the tribe Rhyparochromini. In D. insignis, however, the arrangement is different. Here, metaphase I is usual in showing peripheral position of autosomes and central position of sex chromosomes and m-chromosomes. At metaphase II, however, autosomes, sex chromosomes and m-chromosomes are peripherally placed, an arrangement, which is not reported earlier in the tribe Rhyparochromini.

  3. A new species of Endecous Saussure, 1878 (Orthoptera, Gryllidae) from northeast Brazil with the first X1X20 chromosomal sex system in Gryllidae.

    Science.gov (United States)

    Zefa, Edison; Redü, Darlan Rutz; Da Costa, Maria Kátia Matiotti; Fontanetti, Carmem S; Gottschalk, Marco Silva; Padilha, Giovanna Boff; Fernandes e Silva, Anelise; Martins, Luciano De P

    2014-08-06

    In this paper we describe a new species of Luzarinae cricket collected from the cave "Gruta de Ubajara, municipality of Ubajara, State of Ceará, Brazil, highlighting phallic sclerites morphology and chromosome complement as diagnostic characters. We presented meiotic and mitotic characterization in order to define the karyotype with 2n = 12 + X1X2♂/12 + X1X1X2X2♀. This represents the first record of X1X20 chromosomal sex system in Gryllidae.

  4. WormGender - Open-Source Software for Automatic Caenorhabditis elegans Sex Ratio Measurement.

    Directory of Open Access Journals (Sweden)

    Marta K Labocha

    Full Text Available Fast and quantitative analysis of animal phenotypes is one of the major challenges of current biology. Here we report the WormGender open-source software, which is designed for accurate quantification of sex ratio in Caenorhabditis elegans. The software functions include, i automatic recognition and counting of adult hermaphrodites and males, ii a manual inspection feature that enables manual correction of errors, and iii flexibility to use new training images to optimize the software for different imaging conditions. We evaluated the performance of our software by comparing manual and automated assessment of sex ratio. Our data showed that the WormGender software provided overall accurate sex ratio measurements. We further demonstrated the usage of WormGender by quantifying the high incidence of male (him phenotype in 27 mutant strains. Mutants of nine genes (brc-1, C30G12.6, cep-1, coh-3, him-3, him-5, him-8, skr-1, unc-86 showed significant him phenotype. The WormGender is written in Java and can be installed and run on both Windows and Mac platforms. The source code is freely available together with a user manual and sample data at http://www.QuantWorm.org/. The source code and sample data are also available at http://dx.doi.org/10.6084/m9.figshare.1541248.

  5. Masculine sex ratios, population age structure and the potential spread of HIV in China

    Directory of Open Access Journals (Sweden)

    M. Giovanna Merli

    2010-01-01

    Full Text Available There is much speculation regarding the contribution of China's changing demography to the spread of HIV/AIDS. We employ a bio-behavioral macrosimulation model of the heterosexual spread of HIV/AIDS to evaluate the roles that China's unique demographic conditions -- (1 masculine sex ratios at birth and (2 a population age structure that reflects rapid fertility decline since the 1970's -- play in altering the market for sexual partners, thereby potentially fueling an increase in behaviors associated with greater risk of HIV infection. We first simulate the relative contributions of the sex ratio at birth and the population age structure to the oversupply of males in the market for sexual partners and show that the sex ratio at birth only aggravates the severe oversupply of males which is primarily a consequence of the population age structure. We then examine the potential consequences of this demographic distortion for the spread of HIV infection and show that, to the extent that males adapt to the dearth of suitable female partners by seeking unprotected sexual contacts with female sex workers, the impact of the oversupply of males in the sexual partnership market on the spread of HIV will be severe.

  6. Population structure and the evolution of sexual size dimorphism and sex ratios in an insular population of Florida box turtles (Terrapene carolina bauri)

    Science.gov (United States)

    Dodd, C.K.

    1997-01-01

    Hypotheses in the chelonian literature suggest that in species with sexual size dimorphism, the smaller sex will mature at a smaller size and a younger age than the larger sex, sex ratios should be biased in favor of the earlier maturing sex, and deviations from a 1:1 sex ratio result from maturation of the smaller sex at a younger age. I tested these hypotheses using data collected from 1991 to 1995 on an insular (Egmont Key) population of Florida box turtles, Terrapene carolina bauri. Contrary to predictions, the earlier maturing sex (males) grew to larger sizes than the late maturing sex. Males were significantly larger than females in mean carapace length but not mean body mass. Sex ratios were not balanced, favoring the earlier maturing sex (1.6 males:1 female), but the sex-ratio imbalance did not result from faster maturation of the smaller sex. The imbalance in the sex ratio in Egmont Key's box turtles is not the result of sampling biases; it may result from nest placement. Size-class structure and sex ratios can provide valuable insights into the status and trends of populations of long-lived turtles.

  7. XX/XY System of Sex Determination in the Geophilomorph Centipede Strigamia maritima.

    Directory of Open Access Journals (Sweden)

    Jack E Green

    Full Text Available We show that the geophilomorph centipede Strigamia maritima possesses an XX/XY system of sex chromosomes, with males being the heterogametic sex. This is, to our knowledge, the first report of sex chromosomes in any geophilomorph centipede. Using the recently assembled Strigamia genome sequence, we identified a set of scaffolds differentially represented in male and female DNA sequence. Using quantitative real-time PCR, we confirmed that three candidate X chromosome-derived scaffolds are present at approximately twice the copy number in females as in males. Furthermore, we confirmed that six candidate Y chromosome-derived scaffolds contain male-specific sequences. Finally, using this molecular information, we designed an X chromosome-specific DNA probe and performed fluorescent in situ hybridization against mitotic and meiotic chromosome spreads to identify the Strigamia XY sex-chromosome pair cytologically. We found that the X and Y chromosomes are recognizably different in size during the early pachytene stage of meiosis, and exhibit incomplete and delayed pairing.

  8. Sexual antagonism and meiotic drive cause stable linkage disequilibrium and favour reduced recombination on the X chromosome.

    Science.gov (United States)

    Rydzewski, W T; Carioscia, S A; Liévano, G; Lynch, V D; Patten, M M

    2016-06-01

    Sexual antagonism and meiotic drive are sex-specific evolutionary forces with the potential to shape genomic architecture. Previous theory has found that pairing two sexually antagonistic loci or combining sexual antagonism with meiotic drive at linked autosomal loci augments genetic variation, produces stable linkage disequilibrium (LD) and favours reduced recombination. However, the influence of these two forces has not been examined on the X chromosome, which is thought to be enriched for sexual antagonism and meiotic drive. We investigate the evolution of the X chromosome under both sexual antagonism and meiotic drive with two models: in one, both loci experience sexual antagonism; in the other, we pair a meiotic drive locus with a sexually antagonistic locus. We find that LD arises between the two loci in both models, even when the two loci freely recombine in females and that driving haplotypes will be enriched for male-beneficial alleles, further skewing sex ratios in these populations. We introduce a new measure of LD, Dz', which accounts for population allele frequencies and is appropriate for instances where these are sex specific. Both models demonstrate that natural selection favours modifiers that reduce the recombination rate. These results inform observed patterns of congealment found on driving X chromosomes and have implications for patterns of natural variation and the evolution of recombination rates on the X chromosome. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  9. Sex differences in the brain-an interplay of sex steroid hormones and sex chromosomes.

    Science.gov (United States)

    Grgurevic, Neza; Majdic, Gregor

    2016-09-01

    Although considerable progress has been made in our understanding of brain function, many questions remain unanswered. The ultimate goal of studying the brain is to understand the connection between brain structure and function and behavioural outcomes. Since sex differences in brain morphology were first observed, subsequent studies suggest different functional organization of the male and female brains in humans. Sex and gender have been identified as being a significant factor in understanding human physiology, health and disease, and the biological differences between the sexes is not limited to the gonads and secondary sexual characteristics, but also affects the structure and, more crucially, the function of the brain and other organs. Significant variability in brain structures between individuals, in addition to between the sexes, is factor that complicates the study of sex differences in the brain. In this review, we explore the current understanding of sex differences in the brain, mostly focusing on preclinical animal studies. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  10. Effects of larval-juvenile treatment with perchlorate and co-treatment with thyroxine on zebrafish sex ratios

    Science.gov (United States)

    Mukhi, S.; Torres, L.; Patino, R.

    2007-01-01

    The objective of this study was to determine the effect of larval-juvenile exposure to perchlorate, a thyroid hormone synthesis inhibitor, on the establishment of gonadal sex ratios in zebrafish. Zebrafish were exposed to untreated water or water containing perchlorate at 100 or 250 ppm for a period of 30 days starting at 3 days postfertilization (dpf). Recovery treatments consisted of a combination of perchlorate and exogenous thyroxine (T4; 10 nM). Thyroid histology was assessed at the end of the treatment period (33 dpf), and gonadal histology and sex ratios were determined in fish that were allowed an additional 10-day period of growth in untreated water. As expected, exposure to perchlorate caused changes in thyroid histology consistent with hypothyroidism and these effects were reversed by co-treatment with exogenous T4. Perchlorate did not affect fish survival but co-treatment with T4 induced higher mortality. However, relative to the corresponding perchlorate concentration, co-treatment with T4 caused increased mortality only at a perchlorate concentration of 100 ppm. Perchlorate alone or in the presence of T4 suppressed body length at 43 dpf relative to control values. Perchlorate exposure skewed the sex ratio toward female in a concentration-dependent manner, and co-treatment with T4 not only blocked the feminizing effect of perchlorate but also overcompensated by skewing the sex ratio towards male. Moreover, co-treatment with T4 advanced the onset of spermatogenesis in males. There was no clear association between sex ratios and larval survival or growth. We conclude that endogenous thyroid hormone plays a role in the establishment of gonadal sex phenotype during early development in zebrafish. ?? 2006 Elsevier Inc. All rights reserved.

  11. Divergent actions of long noncoding RNAs on X-chromosome ...

    Indian Academy of Sciences (India)

    2015-10-20

    Oct 20, 2015 ... Organisms with heterochromatic sex chromosomes need to compensate for differences in dosages of ... could also get genetically inactive and late replicating when ... tial to achieve the chromosomal level modifications were.

  12. Origin and domestication of papaya Yh chromosome

    Science.gov (United States)

    VanBuren, Robert; Zeng, Fanchang; Chen, Cuixia; Zhang, Jisen; Wai, Ching Man; Han, Jennifer; Aryal, Rishi; Gschwend, Andrea R.; Wang, Jianping; Na, Jong-Kuk; Huang, Lixian; Zhang, Lingmao; Miao, Wenjing; Gou, Jiqing; Arro, Jie; Guyot, Romain; Moore, Richard C.; Wang, Ming-Li; Zee, Francis; Charlesworth, Deborah; Moore, Paul H.; Yu, Qingyi; Ming, Ray

    2015-01-01

    Sex in papaya is controlled by a pair of nascent sex chromosomes. Females are XX, and two slightly different Y chromosomes distinguish males (XY) and hermaphrodites (XYh). The hermaphrodite-specific region of the Yh chromosome (HSY) and its X chromosome counterpart were sequenced and analyzed previously. We now report the sequence of the entire male-specific region of the Y (MSY). We used a BAC-by-BAC approach to sequence the MSY and resequence the Y regions of 24 wild males and the Yh regions of 12 cultivated hermaphrodites. The MSY and HSY regions have highly similar gene content and structure, and only 0.4% sequence divergence. The MSY sequences from wild males include three distinct haplotypes, associated with the populations’ geographic locations, but gene flow is detected for other genomic regions. The Yh sequence is highly similar to one Y haplotype (MSY3) found only in wild dioecious populations from the north Pacific region of Costa Rica. The low MSY3-Yh divergence supports the hypothesis that hermaphrodite papaya is a product of human domestication. We estimate that Yh arose only ∼4000 yr ago, well after crop plant domestication in Mesoamerica >6200 yr ago but coinciding with the rise of the Maya civilization. The Yh chromosome has lower nucleotide diversity than the Y, or the genome regions that are not fully sex-linked, consistent with a domestication bottleneck. The identification of the ancestral MSY3 haplotype will expedite investigation of the mutation leading to the domestication of the hermaphrodite Yh chromosome. In turn, this mutation should identify the gene that was affected by the carpel-suppressing mutation that was involved in the evolution of males. PMID:25762551

  13. Sex-specific effects of altered competition on nestling growth and survival: an experimental manipulation of brood size and sex ratio.

    Science.gov (United States)

    Nicolaus, Marion; Michler, Stephanie P M; Ubels, Richard; van der Velde, Marco; Komdeur, Jan; Both, Christiaan; Tinbergen, Joost M

    2009-03-01

    1. An increase of competition among adults or nestlings usually negatively affects breeding output. Yet little is known about the differential effects that competition has on the offspring sexes. This could be important because it may influence parental reproductive decisions. 2. In sexual size dimorphic species, two main contradictory mechanisms are proposed regarding sex-specific effects of competition on nestling performance assuming that parents do not feed their chicks differentially: (i) the larger sex requires more resources to grow and is more sensitive to a deterioration of the rearing conditions ('costly sex hypothesis'); (ii) the larger sex has a competitive advantage in intra-brood competition and performs better under adverse conditions ('competitive advantage hypothesis'). 3. In the present study, we manipulated the level of sex-specific sibling competition in a great tit population (Parus major) by altering simultaneously the brood size and the brood sex ratio on two levels: the nest (competition for food among nestlings) and the woodlot where the parents breed (competition for food among adults). We investigated whether altered competition during the nestling phase affected nestling growth traits and survival in the nest and whether the effects differed between males, the larger sex, and females. 4. We found a strong negative and sex-specific effect of experimental brood size on all the nestling traits. In enlarged broods, sexual size dimorphism was smaller which may have resulted from biased mortality towards the less competitive individuals i.e. females of low condition. No effect of brood sex ratio on nestling growth traits was found. 5. Negative brood size effects on nestling traits were stronger in natural high-density areas but we could not confirm this experimentally. 6. Our results did not support the 'costly sex hypothesis' because males did not suffer from higher mortality under harsh conditions. The 'competitive advantage hypothesis' was

  14. Digit Ratio (2D:4D): A Biomarker for Prenatal Sex Steroids and Adult Sex Steroids in Challenge Situations.

    Science.gov (United States)

    Manning, John; Kilduff, Liam; Cook, Christian; Crewther, Blair; Fink, Bernhard

    2014-01-01

    Digit ratio (2D:4D) denotes the relative length of the second and fourth digits. This ratio is considered to be a biomarker of the balance between fetal testosterone (T) and estrogen (E) in a narrow window of early ontogeny. Evidence for this assertion is derived from direct and indirect measures of prenatal hormonal exposure (in experimental animals, via amniotic fluid samples and in the study of sex-typical traits) in relation to 2D:4D. In contrast, the relationships between 2D:4D and levels of sex steroids in adults are less clear, as many correlational studies of 2D:4D and adult sex steroids have concluded that this association is statistically non-significant. Here, we suggest that in order to understand the link between 2D:4D and sex hormones, one must consider both fetal organizing and adult activating effects of T and E. In particular, we hypothesize that 2D:4D correlates with organizing effects on the endocrine system that moderate activating effects in adulthood. We argue that this is particularly evident in "challenging" conditions such as aggressive and sexual encounters, in which individuals show increased levels of T. We discuss this refinement of the 2D:4D paradigm in relation to the links between 2D:4D and sports performance, and aggression.

  15. Sex differences in diurnal rhythms of food intake in mice caused by gonadal hormones and complement of sex chromosomes.

    Science.gov (United States)

    Chen, Xuqi; Wang, Lixin; Loh, Dawn H; Colwell, Christopher S; Taché, Yvette; Reue, Karen; Arnold, Arthur P

    2015-09-01

    We measured diurnal rhythms of food intake, as well as body weight and composition, while varying three major classes of sex-biasing factors: activational and organizational effects of gonadal hormones, and sex chromosome complement (SCC). Four Core Genotypes (FCG) mice, comprising XX and XY gonadal males and XX and XY gonadal females, were either gonad-intact or gonadectomized (GDX) as adults (2.5months); food intake was measured second-by-second for 7days starting 5weeks later, and body weight and composition were measured for 22weeks thereafter. Gonadal males weighed more than females. GDX increased body weight/fat of gonadal females, but increased body fat and reduced body weight of males. After GDX, XX mice had greater body weight and more fat than XY mice. In gonad-intact mice, males had greater total food intake and more meals than females during the dark phase, but females had more food intake and meals and larger meals than males during the light phase. GDX reduced overall food intake irrespective of gonad type or SCC, and eliminated differences in feeding between groups with different gonads. Diurnal phase of feeding was influenced by all three sex-biasing variables. Gonad-intact females had earlier onset and acrophase (peak) of feeding relative to males. GDX caused a phase-advance of feeding, especially in XX mice, leading to an earlier onset of feeding in GDX XX vs. XY mice, but earlier acrophase in GDX males relative to females. Gonadal hormones and SCC interact in the control of diurnal rhythms of food intake. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. An integrated genetic, physical, and transcriptional map of chromosome 13

    Energy Technology Data Exchange (ETDEWEB)

    Scheffer, H.; Kooy, R.F.; Wijngaard, A. [Univ. of Groningen (Netherlands)] [and others

    1994-09-01

    In this study a genetic map containing 20 markers and typed in 40 CEPH families is presented. It includes 7 thusfar untyped microsatellite markers, 7 that have previously been mapped on a subset of 8 CEPH families, one reference marker, D13S71, and three telomeric VNTR markers. Also, 4 intragenic RB1 markers were typed. The markers have an average heterozygosity of 73% (80%, excluding the three RFLPs). The total sex average length of the map is 140 cM. The mean female to male ratio is 1.54. For the non-telomeric part of the chromosome between the markers D13S221 in 13q12 and D13S173 in 13q33-q34, this ratio is 1.99. This ratio is reversed in the telomeric part of the chromosome between D13S173 and D13S234 in distal 13q34, where it is 0.47. A high new mutation frequency of 1% was detected in the (CTTT(T)){sub n} repeat in intron 20 of the RB1 gene. The map has been integrated with 7 microsatellite markers and 2 RFLP markers from CEPH database version 7.0, resulting in a map with 32 markers (28 loci) of chromosome 13q. In addition, a deletion hybrid breakpoint map ordering 50 markers in 18 intervals is constructed. It includes 32 microsatellite markers, 4 genes, 5 STSs, and 9 ESTs. Each of 18 intervals contains at least one microsatellite marker included in the extended genetic map. These data allow a correlation between the genetic and physical map of chromosome 13. New ESTs are currently being identified and localized at this integrated map.

  17. Elucidating the mechanisms of paternal non-disjunction of chromosome 21 in humans.

    Science.gov (United States)

    Savage, A R; Petersen, M B; Pettay, D; Taft, L; Allran, K; Freeman, S B; Karadima, G; Avramopoulos, D; Torfs, C; Mikkelsen, M; Hassold, T J; Sherman, S L

    1998-08-01

    Paternal non-disjunction of chromosome 21 accounts for 5-10% of Down syndrome cases, therefore, relative to the maternally derived cases, little is known about paternally derived trisomy 21. We present the first analysis of recombination and non-disjunction for a large paternally derived population of free trisomy 21 conceptuses ( n = 67). Unlike maternal cases where the ratio of meiosis I (MI) to meiosis II (MII) errors is 3:1, a near 1:1 ratio exists among paternal cases, with a slight excess of MII errors. We found no paternal age effect for the overall population nor when classifying cases according to stage of non-disjunction error. Among 22 MI cases, only five had an observable recombinant event. This differs significantly from the 11 expected events ( P < 0.02, Fisher's exact), suggesting reduced recombination along the non-disjoined chromosomes 21 involved in paternal MI non-disjunction. No difference in recombination was detected among 27 paternal MII cases as compared with controls. However, cases exhibited a slight increase in the frequency of proximal and medial exchange when compared with controls (0.37 versus 0.28, respectively). Lastly, this study confirmed previous reports of excess male probands among paternally derived trisomy 21 cases. However, we report evidence suggesting an MII stage-specific sex ratio disturbance where 2.5 male probands were found for each female proband. Classification of MII cases based on the position of the exchange event suggested that the proband sex ratio disturbance was restricted to non-telomeric exchange cases. Based on these findings, we propose new models to explain the association between paternally derived trisomy 21 and excessive male probands.

  18. Missing girls in India: infanticide, feticide and made-to-order pregnancies? Insights from hospital-based sex-ratio-at-birth over the last century.

    Science.gov (United States)

    Sahni, Mohit; Verma, Neeraj; Narula, D; Varghese, Raji Mathew; Sreenivas, V; Puliyel, Jacob M

    2008-05-21

    There are 44 million missing women in India. Gender bias; neglect of girls, infanticides and feticides are responsible. The sex ratio at birth can be used to examine the influence of antenatal sex selection on the sex ratio. Records from 321,991 deliveries at one hospital over 11 decades were utilized. The middle year in each decade was taken as representative of the decade. Data from 33,524 deliveries were then analyzed. Data for each decade was combined with that of previous decades and compared to the data of subsequent decades to look for any change in the trend. Sex ratio in the second children against sex of the first child was studied separately. The mean sex ratio for the 110 years examined was 910 girls to 1000 boys (95% CI; 891 to 930). The sex ratio dropped significantly from 935 (CI: 905 to 967) before 1979, to 892 (CI: 868 to 918) after 1980 (P = 0.04). The sex ratio in the second child was significantly lower if the first child was a girl [716 (CI: 672 to 762] (Psex ratio fell significantly after 1980 when ultra sound machines for antenatal sex determination became available. The sex ratio in second children if the first was a girl was even lower. Sex selective abortions after antenatal sex determination are thus implicated. However data on second children especially the excess of girls born to mothers who have a previous boy seen in the decade before the advent of antenatal ultra sound machines, suggests that other means of sex selection are also used.

  19. High sex ratios in rural China: declining well-being with age in never-married men.

    Science.gov (United States)

    Zhou, Xudong; Hesketh, Therese

    2017-09-19

    In parts of rural China male-biased sex ratios at birth, combined with out-migration of women, have led to highly male-biased adult sex ratios, resulting in large numbers of men being unable to marry, in a culture where marriage and reproduction are an expectation. The aim of this study was to test the hypotheses that older unmarried men are more predisposed to depression, low self-esteem and aggression than both those who are married, and those who are younger and unmarried. Self-completion questionnaires were administered among men aged 20-40 in 48 villages in rural Guizhou province, southwestern China. Tools used included the Beck Depression Inventory, the Rosenberg's Self-esteem Scale and the Bryant-Smith Aggression Questionnaire. Regression models assessed psychological wellbeing while adjusting for socio-demographic variables. Completed questionnaires were obtained from 957 never-married men, 535 married men aged 30-40, 394 partnered men and 382 unpartnered men aged 20-29. After adjusting for socio-demographic variables, never-married men were more predisposed to depression ( p self-esteem ( p < 0.05) and suicidal tendencies ( p < 0.001). All the psychological measures deteriorated with age in never-married men. In contrast, married men remained stable on these dimensions with age. Never-married men are a psychologically highly vulnerable group in a society where marriage is an expectation. Since the highest birth sex-ratio cohorts have not yet reached reproductive age, the social tragedy of these men will last for at least another generation.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Authors.

  20. Insights into the evolution of mammalian telomerase: Platypus TERT shares similarities with genes of birds and other reptiles and localizes on sex chromosomes

    Directory of Open Access Journals (Sweden)

    Hrdličková Radmila

    2012-06-01

    Full Text Available Abstract Background The TERT gene encodes the catalytic subunit of the telomerase complex and is responsible for maintaining telomere length. Vertebrate telomerase has been studied in eutherian mammals, fish, and the chicken, but less attention has been paid to other vertebrates. The platypus occupies an important evolutionary position, providing unique insight into the evolution of mammalian genes. We report the cloning of a platypus TERT (OanTERT ortholog, and provide a comparison with genes of other vertebrates. Results The OanTERT encodes a protein with a high sequence similarity to marsupial TERT and avian TERT. Like the TERT of sauropsids and marsupials, as well as that of sharks and echinoderms, OanTERT contains extended variable linkers in the N-terminal region suggesting that they were present already in basal vertebrates and lost independently in ray-finned fish and eutherian mammals. Several alternatively spliced OanTERT variants structurally similar to avian TERT variants were identified. Telomerase activity is expressed in all platypus tissues like that of cold-blooded animals and murine rodents. OanTERT was localized on pseudoautosomal regions of sex chromosomes X3/Y2, expanding the homology between human chromosome 5 and platypus sex chromosomes. Synteny analysis suggests that TERT co-localized with sex-linked genes in the last common mammalian ancestor. Interestingly, female platypuses express higher levels of telomerase in heart and liver tissues than do males. Conclusions OanTERT shares many features with TERT of the reptilian outgroup, suggesting that OanTERT represents the ancestral mammalian TERT. Features specific to TERT of eutherian mammals have, therefore, evolved more recently after the divergence of monotremes.

  1. 46,XX T testicular disorder of sex development. Case report.

    Science.gov (United States)

    Pastor Guzmán, José María; Pastor Navarro, Hector; Quintanilla Mata, María Luisa; Carrión López, Pedro; Martínez Ruíz, Jesús; Martínez Sanchiz, Carlos; Perán Teruel, Miguel; Virseda Rodríguez, Julio Antonio

    2011-06-01

    We present a case of X-Y translocation with male phenotype (46,XX testicular disorder of sex development) and review the literature. Disorders of sex development with mismatch of genetic, gonadal and phenotypic sex are quite rare, and some are due to genetic or chromosomal abnormalities. The karyotype was investigated by a cytogenetic study of peripheral blood (phytohemagglutinin-timulated lymphocyte culture over 72 hours). G-banding analysis of 25 metaphases showed a 46,XX chromosome constitution (46 chromosomes with XX sexual composition). Fluorescence in situ hybridization (FISH) analysis with probes for X centromeres and the sex-determining region of the Y chromosome (SRY) (testis-determining factor gene) showed two X chromosomes. The analysis also showed the SRY signal in the telomeric region of the short arm of one of the chromosomes. In recent years, a number of other genes involved in disorders of sex development in animals and humans have also been identified. Genetic defects in the peptide hormone receptors, members of the steroid receptor superfamily, and other transcription factors, as well as any of a series of enzymes and cofactors involved in steroid biosynthesis can cause abnormal determination and differentiation. Although chromosomal abnormalities are rarely present in patients with apparently normal external genitalia, they should be considered in urology consultations by adolescents and adults, particularly in the investigation of gynecomastia or infertility.

  2. C-banding and fluorescent in situ hybridization with rDNA sequences in chromosomes of Cycloneda sanguinea Linnaeus (Coleoptera, Coccinellidae

    Directory of Open Access Journals (Sweden)

    Eliane Mariza Dortas Maffei

    2004-01-01

    Full Text Available The aim of this study was to describe mitotic and meiotic chromosomes of Cycloneda sanguinea using C-banding, fluorescent in situ hybridization (FISH rDNA probes, and sequential FISH/Ag-NOR staining. The chromosome number was 2n = 18 + XX for females and 2n = 18 + Xy for males. The X chromosome was metacentric and the Y chromosome was very small. During meiosis, the karyotypic meioformula was n = 9 + Xy p, and sex chromosomes configured a parachute at metaphase I. At the beginning of pachytene, bivalents were still individualized, and sex chromosomes were associated end-to-end through the heteropycnotic region of the X chromosome. Later in pachytene, further condensation led to the formation of a pseudo-ring by the sex bivalent. All chromosomes showed pericentromeric heterochromatin. FISH and sequential FISH/Ag-NOR staining evidenced the location of the nucleolar organizer region in one pair of autosomes (at spermatogonial metaphase. During meiosis, these genes were mapped to a region outside the sex vesicle by FISH, although Xy p was deeply stained with silver at metaphase I. These results suggest that these argyrophilic substances are of a nucleolar protein nature, and seem to be synthesized by a pair of autosomes and imported during meiosis (prophase I to the sex pair, during the association of the sex chromosomes.

  3. Parallel distribution of sexes within left and right uterine horns in Holstein dairy cows: evidence that the effect of side of pregnancy on sex ratio could be breed-specific in cattle.

    Science.gov (United States)

    Gharagozlou, F; Vojgani, M; Akbarinejad, V; Niasari-Naslaji, A; Hemmati, M; Youssefi, R

    2013-11-30

    Dissimilar distribution of male and female calves within left and right uterine horns has been observed in beef cows. A retrospective study was conducted to investigate the effect of side of pregnancy on secondary sex ratio in Holstein dairy cows. Data associated with sex of calves, side of pregnancy, sire, dam, parity number of dam, AI technician, season and year were retrieved from the database of a Holstein dairy farm. In total, data consisted of 6515 birth records from 3155 dams and 244 sires across years 2001-2010. Data were analyzed using logistic regression. There was no difference in proportion of male and female calves between left (52.9% and 47.1%, respectively) and right (53.2% and 46.8%, respectively) uterine horns (P>0.05). AI technician, year, season and parity of dam did not affect secondary sex ratio (P>0.05). Secondary sex ratio of left and right uterine horns, and consequently, overall secondary sex ratio (53.1%) were skewed toward males as compared with hypothetical secondary sex ratio of 50% (Pcows. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. The Facial Width-to-Height Ratio Predicts Sex Drive, Sociosexuality, and Intended Infidelity.

    Science.gov (United States)

    Arnocky, Steven; Carré, Justin M; Bird, Brian M; Moreau, Benjamin J P; Vaillancourt, Tracy; Ortiz, Triana; Marley, Nicole

    2017-09-19

    Previous research has linked the facial width-to-height ratio (FWHR) to a host of psychological and behavioral characteristics, primarily in men. In two studies, we examined novel links between FWHR and sex drive. In Study 1, a sample of 145 undergraduate students revealed that FWHR positively predicted sex drive. There were no significant FWHR × sex interactions, suggesting that FWHR is linked to sexuality among both men and women. Study 2 replicated and extended these findings in a sample of 314 students collected from a different Canadian city, which again demonstrated links between the FWHR and sex drive (also in both men and women), as well as sociosexuality and intended infidelity (men only). Internal meta-analytic results confirm the link between FWHR and sex drive among both men and women. These results suggest that FWHR may be an important morphological index of human sexuality.

  5. Does the sex ratio at sexual maturity affect men's later-life mortality risks? Evidence from historical China.

    Science.gov (United States)

    Zang, Emma; Zheng, Hui

    2018-04-01

    This study examines the relationship between the male-to-female sex ratio (measured as the proportion male) at sexual maturity and later-life mortality risks in the context of pre-industrial northeast China, using registration data from the Qing Dynasty. We find that a higher male-to-female sex ratio at sexual maturity is associated with a higher later-life mortality risk among men. This association is likely due to the long-term adverse consequences of stress caused by low mate availability at sexual maturity. We further find that a high sex ratio at sexual maturity mitigates the health benefits of marriage and exacerbates the health disadvantages of holding an official position in Qing China. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Missing Girls in India: Infanticide, Feticide and Made-to-Order Pregnancies? Insights from Hospital-Based Sex-Ratio-at-Birth over the Last Century

    Science.gov (United States)

    Sahni, Mohit; Verma, Neeraj; Narula, D.; Varghese, Raji Mathew; Sreenivas, V.; Puliyel, Jacob M.

    2008-01-01

    Background There are 44 million missing women in India. Gender bias; neglect of girls, infanticides and feticides are responsible. The sex ratio at birth can be used to examine the influence of antenatal sex selection on the sex ratio. Materials and Methods Records from 321,991 deliveries at one hospital over 11 decades were utilized. The middle year in each decade was taken as representative of the decade. Data from 33,524 deliveries were then analyzed. Data for each decade was combined with that of previous decades and compared to the data of subsequent decades to look for any change in the trend. Sex ratio in the second children against sex of the first child was studied separately. Results The mean sex ratio for the 110 years examined was 910 girls to 1000 boys (95% CI; 891 to 930). The sex ratio dropped significantly from 935 (CI: 905 to 967) before 1979, to 892 (CI: 868 to 918) after 1980 (P = 0.04). The sex ratio in the second child was significantly lower if the first child was a girl [716 (CI: 672 to 762] (P<0.001). On the other hand, there was an excess of girls born to mothers whose first child was boy [1140 girls per 1000 boys (CI: 1072 to 1212 P<0.001)]. Conclusions The sex ratio fell significantly after 1980 when ultra sound machines for antenatal sex determination became available. The sex ratio in second children if the first was a girl was even lower. Sex selective abortions after antenatal sex determination are thus implicated. However data on second children especially the excess of girls born to mothers who have a previous boy seen in the decade before the advent of antenatal ultra sound machines, suggests that other means of sex selection are also used. PMID:18493614

  7. Sex Ratio And Size At First Maturity Of Blue Swimming Crab (Portunus pelagicus Salemo Island Pangkep Regency

    Directory of Open Access Journals (Sweden)

    Muh. Saleh Nurdin

    2016-03-01

    Full Text Available Blue swimming crab (Portunuspelagicus is aeconomical valuable fisheries importantcommodity  due to the high demand and availability jobs created for the fishermen. Due to their high demand blue swimming crab heavily exploited from Salemo Island. This study aimed at comparing the sex ratio and the size at first maturity of blue swimming crab caught in mangrove ecosystems, coral reefs, and seagrass. Sex ratio was analyzed using chi square test and the size at first maturity was analyzed using the Spearman-Karber formula. The results showed the sex ratio ofmales and femalessmall crab caught in every ecosystem is balanced. The size at first maturity of blue swimming crab caught in mangrove, seagrass and coral reefs, each to the male 81,08 mm, 102,36 mm and 102,87 mm in width and size of female 94,54 mm, 83,35 mm, 98,31 mm width. In a reference to government regulations, the blue male swimming crab caught in the coral reef and seagrass ecosystems have yet to size at first maturity is allowed to be captured. Keywords: blue swimming crab, sex ratio,size at first maturity, Salemo Island

  8. The Effects of Sex-Ratio and Density on Locomotor Activity in the House Fly, Musca domestica

    OpenAIRE

    Bahrndorff, Simon; Kjærsgaard, Anders; Pertoldi, Cino; Loeschcke, Volker; Schou, Toke M.; Skovgård, Henrik; Hald, Birthe

    2012-01-01

    Although locomotor activity is involved in almost all behavioral traits, there is a lack of knowledge on what factors affect it. This study examined the effects of sex-ratio and density on the circadian rhythm of locomotor activity of adult Musca domestica L. (Diptera: Muscidae) using an infra-red light system. Sex-ratio significantly affected locomotor activity, increasing with the percentage of males in the vials. In accordance with other studies, males were more active than females, but th...

  9. Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome

    Science.gov (United States)

    Machiela, Mitchell J.; Zhou, Weiyin; Karlins, Eric; Sampson, Joshua N.; Freedman, Neal D.; Yang, Qi; Hicks, Belynda; Dagnall, Casey; Hautman, Christopher; Jacobs, Kevin B.; Abnet, Christian C.; Aldrich, Melinda C.; Amos, Christopher; Amundadottir, Laufey T.; Arslan, Alan A.; Beane-Freeman, Laura E.; Berndt, Sonja I.; Black, Amanda; Blot, William J.; Bock, Cathryn H.; Bracci, Paige M.; Brinton, Louise A.; Bueno-de-Mesquita, H Bas; Burdett, Laurie; Buring, Julie E.; Butler, Mary A.; Canzian, Federico; Carreón, Tania; Chaffee, Kari G.; Chang, I-Shou; Chatterjee, Nilanjan; Chen, Chu; Chen, Constance; Chen, Kexin; Chung, Charles C.; Cook, Linda S.; Crous Bou, Marta; Cullen, Michael; Davis, Faith G.; De Vivo, Immaculata; Ding, Ti; Doherty, Jennifer; Duell, Eric J.; Epstein, Caroline G.; Fan, Jin-Hu; Figueroa, Jonine D.; Fraumeni, Joseph F.; Friedenreich, Christine M.; Fuchs, Charles S.; Gallinger, Steven; Gao, Yu-Tang; Gapstur, Susan M.; Garcia-Closas, Montserrat; Gaudet, Mia M.; Gaziano, J. Michael; Giles, Graham G.; Gillanders, Elizabeth M.; Giovannucci, Edward L.; Goldin, Lynn; Goldstein, Alisa M.; Haiman, Christopher A.; Hallmans, Goran; Hankinson, Susan E.; Harris, Curtis C.; Henriksson, Roger; Holly, Elizabeth A.; Hong, Yun-Chul; Hoover, Robert N.; Hsiung, Chao A.; Hu, Nan; Hu, Wei; Hunter, David J.; Hutchinson, Amy; Jenab, Mazda; Johansen, Christoffer; Khaw, Kay-Tee; Kim, Hee Nam; Kim, Yeul Hong; Kim, Young Tae; Klein, Alison P.; Klein, Robert; Koh, Woon-Puay; Kolonel, Laurence N.; Kooperberg, Charles; Kraft, Peter; Krogh, Vittorio; Kurtz, Robert C.; LaCroix, Andrea; Lan, Qing; Landi, Maria Teresa; Marchand, Loic Le; Li, Donghui; Liang, Xiaolin; Liao, Linda M.; Lin, Dongxin; Liu, Jianjun; Lissowska, Jolanta; Lu, Lingeng; Magliocco, Anthony M.; Malats, Nuria; Matsuo, Keitaro; McNeill, Lorna H.; McWilliams, Robert R.; Melin, Beatrice S.; Mirabello, Lisa; Moore, Lee; Olson, Sara H.; Orlow, Irene; Park, Jae Yong; Patiño-Garcia, Ana; Peplonska, Beata; Peters, Ulrike; Petersen, Gloria M.; Pooler, Loreall; Prescott, Jennifer; Prokunina-Olsson, Ludmila; Purdue, Mark P.; Qiao, You-Lin; Rajaraman, Preetha; Real, Francisco X.; Riboli, Elio; Risch, Harvey A.; Rodriguez-Santiago, Benjamin; Ruder, Avima M.; Savage, Sharon A.; Schumacher, Fredrick; Schwartz, Ann G.; Schwartz, Kendra L.; Seow, Adeline; Wendy Setiawan, Veronica; Severi, Gianluca; Shen, Hongbing; Sheng, Xin; Shin, Min-Ho; Shu, Xiao-Ou; Silverman, Debra T.; Spitz, Margaret R.; Stevens, Victoria L.; Stolzenberg-Solomon, Rachael; Stram, Daniel; Tang, Ze-Zhong; Taylor, Philip R.; Teras, Lauren R.; Tobias, Geoffrey S.; Van Den Berg, David; Visvanathan, Kala; Wacholder, Sholom; Wang, Jiu-Cun; Wang, Zhaoming; Wentzensen, Nicolas; Wheeler, William; White, Emily; Wiencke, John K.; Wolpin, Brian M.; Wong, Maria Pik; Wu, Chen; Wu, Tangchun; Wu, Xifeng; Wu, Yi-Long; Wunder, Jay S.; Xia, Lucy; Yang, Hannah P.; Yang, Pan-Chyr; Yu, Kai; Zanetti, Krista A.; Zeleniuch-Jacquotte, Anne; Zheng, Wei; Zhou, Baosen; Ziegler, Regina G.; Perez-Jurado, Luis A.; Caporaso, Neil E.; Rothman, Nathaniel; Tucker, Margaret; Dean, Michael C.; Yeager, Meredith; Chanock, Stephen J.

    2016-01-01

    To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases. PMID:27291797

  10. Marriage season, promptness of successful pregnancy and first-born sex ratio in a historical natural fertility population - evidence for sex-dependent early pregnancy loss?

    Science.gov (United States)

    Nonaka, K.; Desjardins, Bertrand; Charbonneau, Hubert; Légaré, Jacques; Miura, Teiji

    We investigated population-based vital records of the seventeenth and eighteenth century French Canadian population to assess the effects of marriage season on the outcome of the first births under natural fertility conditions (n=21,698 marriages). Promptness of the first successful conception after marriage differed according to marriage season; the proportion of marriages with a marriage-first birth interval of 8.0-10.0 months was lowest (34%) for marriages in August-October (P=0.001). Although the male/female sex ratio of the babies born with an interval of 8.0-10.0 months was generally higher (1.10) than those with an interval of 10.0-24.0 months (1.05), the marriages in August-October resulted in a significantly reduced sex ratio (0.96) among only the prompt conceptions (P=0.026). We discuss whether this seasonal reduction of the sex ratio could be partly explained by a clustered pregnancy loss of male zygotes in early pregnancy.

  11. Fissions, fusions, and translocations shaped the karyotype and multiple sex chromosome constitution of the northeast-Asian wood white butterfly, Leptidea amurensis

    Czech Academy of Sciences Publication Activity Database

    Šíchová, Jindra; Ohno, M.; Dincă, V.; Watanabe, M.; Sahara, K.; Marec, František

    2016-01-01

    Roč. 118, č. 3 (2016), s. 457-471 ISSN 0024-4066 R&D Projects: GA ČR(CZ) GA14-22765S Grant - others:GA JU(CZ) 052/2013/P Institutional support: RVO:60077344 Keywords : karyotype evolution * meiotic pairing * multiple sex chromosomes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.288, year: 2016 http://onlinelibrary.wiley.com/doi/10.1111/bij.12756/full

  12. The effects of sex-ratio and density on locomotor activity in the house fly, Musca domestica

    DEFF Research Database (Denmark)

    Bahrndorff, Simon; Kjaersgaard, Anders; Pertoldi, Cino

    2012-01-01

    Although locomotor activity is involved in almost all behavioral traits, there is a lack of knowledge on what factors affect it. This study examined the effects of sex-ratio and density on the circadian rhythm of locomotor activity of adult Musca domestica L. (Diptera: Muscidae) using an infra......-red light system. Sex-ratio significantly affected locomotor activity, increasing with the percentage of males in the vials. In accordance with other studies, males were more active than females, but the circadian rhythm of the two sexes was not constant over time and changed during the light period...... of the behavioral interactions between houseflies and highlight the importance of these factors when designing behavioral experiments using M. domestica....

  13. Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice

    Science.gov (United States)

    de Boer, Esther; Jasin, Maria; Keeney, Scott

    2015-01-01

    Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency. PMID:26251527

  14. Sex determination in mythology and history.

    Science.gov (United States)

    Mittwoch, Ursula

    2005-02-01

    The history of ideas on how the sexes became divided spans at least three thousand years. The biblical account of the origin of Eve, and the opinions of the philosophers of classical Greece, have unexpected bearings on present-day ideas. The scientific study of sex determination can be said to have begun in the 17th century with the discovery of spermatozoa, but the origin and function of the "spermatic animalcules" eluded investigators until 1841. The mammalian egg was discovered in 1827, and in the last quarter of the century fertilization was observed. The view current at that time, that sex determination was under environmental control, gave way to the idea of chromosomal determination in the first quarter of the 20th century. The study of human and other mammalian chromosomes during the third quarter of the century, and the discovery of sex-chromosome abnormalities, emphasized the importance of the Y chromosome for male sex determination. The last quarter of the century witnessed a hunt for the "testis-determining" gene, thought to be responsible for the differentiation of Sertoli cells, and culminating in the isolation of SRY (Sry in the mouse). However, an increasing number of additional genes and growth factors were found to be required for the establishment of male sex. During the same period evidence emerged that male development was accompanied by enhanced growth, both of gonads and whole embryos. An unexpected finding was the demonstration of temperature-dependent sex determination in reptiles. With the advent of the 21st century, it was shown that Sry induces cell proliferation in fetal mouse gonads, and it has been suggested that male sex differentiation in mammals requires a higher metabolic rate. These insights could lead to a better understanding and improved treatment of abnormalities of sexual development.

  15. Effect of Corticosterone and Hen Body Mass on Primary Sex Ratio in Laying Hen (Gallusgallus), Using Unincubated Eggs1

    NARCIS (Netherlands)

    Aslam, M.A.; Groothuis, T.G.G.; Smits, M.A.; Woelders, H.

    2014-01-01

    In various studies, chronic elevation of corticosterone levels in female birds under natural or experimental conditions resulted in female biased offspring sex ratios. In chicken, one study with injected corticosterone resulted in a male sex ratio bias. In the current study, we chronically elevated

  16. Effect of corticosterone and hen body mass on primary sex ratio in laying hen (Gallus gallus), using unincubated eggs

    NARCIS (Netherlands)

    Aslam, Muhammad Aamir; Groothuis, Ton G. G.; Smits, Mari A.; Woelders, Henri

    In various studies, chronic elevation of corticosterone levels in female birds under natural or experimental conditions resulted in female biased offspring sex ratios. In chicken, one study with injected corticosterone resulted in a male sex ratio bias. In the current study, we chronically elevated

  17. Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

    DEFF Research Database (Denmark)

    Timmermann, Clara Amalie Gade; Choi, Anna L.; Petersen, Maria Skaalum

    2017-01-01

    This study was undertaken to assess the potential impact of maternal exposures to polychlorinated biphenyl (PCB), dichlorodiphenyl dichloroethylene (DDE) and methylmercury on the secondary sex ratios (the ratio of male to female live births) over a span of 23 years. The study includes prospective...... data from three Faroese birth cohorts, with a total of 2,152 healthy mother-child dyads recruited between 1986 and 2009. The Faroe Islands is a subarctic fishing community, where pilot whale meat and blubber are part of the traditional marine diet. Exposures were measured in maternal hair, serum...... or umbilical cord blood. Confounder adjusted logistic regression models were used to assess the associations between maternal exposures and the secondary sex ratio. A doubling in ΣPCB, p,p'-DDE and mercury concentrations were associated with increased odds by 8% (95% CI = 0-16%), 7% (95% CI = 0-14%) and 9% (95...

  18. Induction of inherited sterility and sex ratio distribution due to exposure to substerilising doses of gamma radiation in cotton bollworm Earias vittella fabricius

    International Nuclear Information System (INIS)

    Tamhankar, A.J.; Shantharam, K.

    2005-01-01

    Substerilising doses of gamma radiation induced inherited sterility and sex ratio distortion in the cotton bollworm Earias vittella fabricius. Adults irradiated with 75 Gy and self-crossed, provided sterile F 1 adults, suitable for direct use in sterile insect technique (SIT). In case of 50 Gy, the F 1 adults, when backcrossed, produced F 2 progeny with sex ratio in favour of females (1: >3). With 25 Gy, a sex ratio distortion was recorded in F 1 (1 male: 2.25 females) and self-crossing of F 1 resulted in progeny with a sex ratio of 3:1. Backcrossing of the F 1 female produced F 2 progeny with a sex ratio of 1:5. These results have implications in improving cost/benefit ratio of SIT for this species. (author)

  19. Sex-ratio biasing towards daughters among lower-ranking co-wives in Rwanda

    NARCIS (Netherlands)

    Pollet, Thomas V.; Fawcett, Tim W.; Buunk, Abraham P.; Nettle, Daniel

    2009-01-01

    There is considerable debate as to whether human females bias the sex ratio of their offspring as a function of their own condition. We apply the Trivers-Willard prediction-that mothers in poor condition will overproduce daughters-to a novel measure of condition, namely wife rank within a polygynous

  20. Evolutionary Dynamics of the Gametologous CTNNB1 Gene on the Z and W Chromosomes of Snakes.

    Science.gov (United States)

    Laopichienpong, Nararat; Muangmai, Narongrit; Chanhome, Lawan; Suntrarachun, Sunutcha; Twilprawat, Panupon; Peyachoknagul, Surin; Srikulnath, Kornsorn

    2017-03-01

    Snakes exhibit genotypic sex determination with female heterogamety (ZZ males and ZW females), and the state of sex chromosome differentiation also varies among lineages. To investigate the evolutionary history of homologous genes located in the nonrecombining region of differentiated sex chromosomes in snakes, partial sequences of the gametologous CTNNB1 gene were analyzed for 12 species belonging to henophid (Cylindrophiidae, Xenopeltidae, and Pythonidae) and caenophid snakes (Viperidae, Elapidae, and Colubridae). Nonsynonymous/synonymous substitution ratios (Ka/Ks) in coding sequences were low (Ka/Ks < 1) between CTNNB1Z and CTNNB1W, suggesting that these 2 genes may have similar functional properties. However, frequencies of intron sequence substitutions and insertion–deletions were higher in CTNNB1Z than CTNNB1W, suggesting that Z-linked sequences evolved faster than W-linked sequences. Molecular phylogeny based on both intron and exon sequences showed the presence of 2 major clades: 1) Z-linked sequences of Caenophidia and 2) W-linked sequences of Caenophidia clustered with Z-linked sequences of Henophidia, which suggests that the sequence divergence between CTNNB1Z and CTNNB1W in Caenophidia may have occurred by the cessation of recombination after the split from Henophidia.

  1. Contrasting Patterns of Genomic Diversity Reveal Accelerated Genetic Drift but Reduced Directional Selection on X-Chromosome in Wild and Domestic Sheep Species.

    Science.gov (United States)

    Chen, Ze-Hui; Zhang, Min; Lv, Feng-Hua; Ren, Xue; Li, Wen-Rong; Liu, Ming-Jun; Nam, Kiwoong; Bruford, Michael W; Li, Meng-Hua

    2018-04-01

    Analyses of genomic diversity along the X chromosome and of its correlation with autosomal diversity can facilitate understanding of evolutionary forces in shaping sex-linked genomic architecture. Strong selective sweeps and accelerated genetic drift on the X-chromosome have been inferred in primates and other model species, but no such insight has yet been gained in domestic animals compared with their wild relatives. Here, we analyzed X-chromosome variability in a large ovine data set, including a BeadChip array for 943 ewes from the world's sheep populations and 110 whole genomes of wild and domestic sheep. Analyzing whole-genome sequences, we observed a substantially reduced X-to-autosome diversity ratio (∼0.6) compared with the value expected under a neutral model (0.75). In particular, one large X-linked segment (43.05-79.25 Mb) was found to show extremely low diversity, most likely due to a high density of coding genes, featuring highly conserved regions. In general, we observed higher nucleotide diversity on the autosomes, but a flat diversity gradient in X-linked segments, as a function of increasing distance from the nearest genes, leading to a decreased X: autosome (X/A) diversity ratio and contrasting to the positive correlation detected in primates and other model animals. Our evidence suggests that accelerated genetic drift but reduced directional selection on X chromosome, as well as sex-biased demographic events, explain low X-chromosome diversity in sheep species. The distinct patterns of X-linked and X/A diversity we observed between Middle Eastern and non-Middle Eastern sheep populations can be explained by multiple migrations, selection, and admixture during the domestic sheep's recent postdomestication demographic expansion, coupled with natural selection for adaptation to new environments. In addition, we identify important novel genes involved in abnormal behavioral phenotypes, metabolism, and immunity, under selection on the sheep X-chromosome.

  2. Enzymatic amplification of a Y chromosome repeat in a single blastomere allows identification of the sex of preimplantation mouse embryos

    International Nuclear Information System (INIS)

    Bradbury, M.W.; Isola, L.M.; Gordon, J.W.

    1990-01-01

    The polymerase chain reaction (PCR) technique has been adapted to identify the sex of preimplantation mouse embryos rapidly. PCR was used to amplify a specific repeated DNA sequence on the Y chromosome from a single isolated blastomere in under 12 hr. The remainder of the biopsied embryo was then transferred to a pseudopregnant female and carried to term. Using this technique, 72% of embryos can be classed as potentially either male or female. Transfers of such embryos have produced pregnancies with 8/8 fetuses (100%) being of the predicted sex. Variations of the technique have demonstrated certain limitations to the present procedure as well as indicated possible strategies for improvement of the assay. The PCR technique may have wide application in the genetic analysis of preimplantation embryos

  3. The chicken Z chromosome is enriched for genes with preferential expression in ovarian somatic cells

    Czech Academy of Sciences Publication Activity Database

    Mořkovský, L.; Storchová, R.; Plachý, Jiří; Ivánek, Robert; Divina, Petr; Hejnar, Jiří

    2010-01-01

    Roč. 70, č. 2 (2010), s. 129-136 ISSN 0022-2844 Institutional research plan: CEZ:AV0Z50520514 Keywords : Z chromosome * meiotic sex chromosome inactivation * sex ual antagonisms Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.311, year: 2010

  4. Sex Determination, Sex Ratios, and Genetic Conflict

    NARCIS (Netherlands)

    Werren, John H.; Beukeboom, Leo W.

    1998-01-01

    Genetic mechanisms of sex determination are unexpectedly diverse and change rapidly during evolution. We review the role of genetic conflict as the driving force behind this diversity and turnover. Genetic conflict occurs when different components of a genetic system are subject to selection in

  5. Reduced polymorphism associated with X chromosome meiotic drive in the stalk-eyed fly Teleopsis dalmanni.

    Directory of Open Access Journals (Sweden)

    Sarah J Christianson

    Full Text Available Sex chromosome meiotic drive has been suggested as a cause of several evolutionary genetic phenomena, including genomic conflicts that give rise to reproductive isolation between new species. In this paper we present a population genetic analysis of X chromosome drive in the stalk-eyed fly, Teleopsis dalmanni, to determine how this natural polymorphism influences genetic diversity. We analyzed patterns of DNA sequence variation at two X-linked regions (comprising 1325 bp approximately 50 cM apart and one autosomal region (comprising 921 bp for 50 males, half of which were collected in the field from one of two allopatric locations and the other half were derived from lab-reared individuals with known brood sex ratios. These two populations are recently diverged but exhibit partial postzygotic reproductive isolation, i.e. crosses produce sterile hybrid males and fertile females. We find no nucleotide or microsatellite variation on the drive X chromosome, whereas the same individuals show levels of variation at autosomal regions that are similar to field-collected flies. Furthermore, one field-caught individual collected 10 years previously had a nearly identical X haplotype to the drive X, and is over 2% divergent from other haplotypes sampled from the field. These results are consistent with a selective sweep that has removed genetic variation from much of the drive X chromosome. We discuss how this finding may relate to the rapid evolution of postzygotic reproductive isolation that has been documented for these flies.

  6. Sex-Ratio and Gender Differences in Depression in an Unselected Adult Population.

    Science.gov (United States)

    Baumgart, E. P.; Oliver, J. M.

    1981-01-01

    Neither sex-ratio nor gender differences in depression were found in adult sample, similar to pattern found among university students. No demographic variable was correlated significantly with depression. Suggests results may be due to the elimination of face-to-face interviews, which expose males to greater negative repercussions for exhibiting…

  7. Forensic use of Y-chromosome DNA: a general overview

    NARCIS (Netherlands)

    M.H. Kayser (Manfred)

    2017-01-01

    textabstractThe male-specific part of the human Y chromosome is widely used in forensic DNA analysis, particularly in cases where standard autosomal DNA profiling is not informative. A Y-chromosomal gene fragment is applied for inferring the biological sex of a crime scene trace donor. Haplotypes

  8. Common vole (Microtus arvalis) population sex ratio: biases and process variation

    Czech Academy of Sciences Publication Activity Database

    Bryja, Josef; Nesvadbová, Jiřina; Heroldová, Marta; Jánová, Eva; Losík, J.; Trebatická, L.; Tkadlec, Emil

    2005-01-01

    Roč. 83, č. 11 (2005), s. 1391-1399 ISSN 0008-4301 R&D Projects: GA ČR(CZ) GA524/01/1316; GA ČR(CZ) GP206/02/P068; GA ČR(CZ) GA206/04/2003 Institutional research plan: CEZ:AV0Z60930519 Keywords : common vole * population sex ratio Subject RIV: EH - Ecology, Behaviour Impact factor: 1.175, year: 2005

  9. Cytogenetic abnormality in man, wider implications of theories of sex chromatin origin.

    Science.gov (United States)

    MILES, C P

    1962-01-01

    Female nuclei may be identified by means of sex chromatin. In general the number of sex chromatin bodies is one less than the number of X chromosomes. An exception to this rule is a case of sex chromatin-positive XO Turner's syndrome. This case suggests the possibility of sex chromatin-positive XY males, and it may be evidence for chromosomal differentiation.

  10. Chimeric Sex-Determining Chromosomal Regions and Dysregulation of Cell-Type Identity in a Sterile Zygosaccharomyces Allodiploid Yeast.

    Directory of Open Access Journals (Sweden)

    Melissa Bizzarri

    Full Text Available Allodiploidization is a fundamental yet evolutionarily poorly characterized event, which impacts genome evolution and heredity, controlling organismal development and polyploid cell-types. In this study, we investigated the sex determination system in the allodiploid and sterile ATCC 42981 yeast, a member of the Zygosaccharomyces rouxii species complex, and used it to study how a chimeric mating-type gene repertoire contributes to hybrid reproductive isolation. We found that ATCC 42981 has 7 MAT-like (MTL loci, 3 of which encode α-idiomorph and 4 encode a-idiomorph. Two phylogenetically divergent MAT expression loci were identified on different chromosomes, accounting for a hybrid a/α genotype. Furthermore, extra a-idimorph-encoding loci (termed MTLa copies 1 to 3 were recognized, which shared the same MATa1 ORFs but diverged for MATa2 genes. Each MAT expression locus was linked to a HML silent cassette, while the corresponding HMR loci were located on another chromosome. Two putative parental sex chromosome pairs contributed to this unusual genomic architecture: one came from an as-yet-undescribed taxon, which has the NCYC 3042 strain as a unique representative, while the other did not match any MAT-HML and HMR organizations previously described in Z. rouxii species. This chimeric rearrangement produces two copies of the HO gene, which encode for putatively functional endonucleases essential for mating-type switching. Although both a and α coding sequences, which are required to obtain a functional cell-type a1-α2 regulator, were present in the allodiploid ATCC 42981 genome, the transcriptional circuit, which regulates entry into meiosis in response to meiosis-inducing salt stress, appeared to be turned off. Furthermore, haploid and α-specific genes, such as MATα1 and HO, were observed to be actively transcribed and up-regulated under hypersaline stress. Overall, these evidences demonstrate that ATCC 42981 is unable to repress haploid

  11. Two males with SRY-positive 46,XX testicular disorder of sex development.

    Science.gov (United States)

    Gunes, Sezgin; Asci, Ramazan; Okten, Gülsen; Atac, Fatih; Onat, Onur E; Ogur, Gonul; Aydin, Oguz; Ozcelik, Tayfun; Bagci, Hasan

    2013-02-01

    The 46,XX testicular disorder of sex development (46,XX testicular DSD) is a rare phenotype associated with disorder of the sex chromosomes. We describe the clinical, molecular, and cytogenetic findings of a 16- and a 30-year-old male patient with sex-determining region Y (SRY)-positive 46,XX testicular DSD. Chromosomal analysis revealed 46,XX karyotype. Fluorescence in situ hybridization (FISH) showed the SRY region translocated to the short arm of the X chromosome. The presence of the SRY gene was also confirmed by polymerase chain reaction (PCR). The X chromosome inactivation (XCI) assay showed that both patients have a random pattern of X chromosome inactivation. This report compares the symptoms and features of the SRY-positive 46,XX testicular DSD patients.

  12. Preconception stress and the secondary sex ratio in a population-based preconception cohort.

    Science.gov (United States)

    Bae, Jisuk; Lynch, Courtney D; Kim, Sungduk; Sundaram, Rajeshwari; Sapra, Katherine J; Buck Louis, Germaine M

    2017-03-01

    To examine the association between preconception parental stress and the secondary sex ratio, defined as the ratio of males to females at birth. A population-based preconception cohort. Not applicable. A total of 235 couples who were enrolled before conception in Michigan and Texas between 2005 and 2009 and who had a singleton birth during the follow-up period. Couples were interviewed separately at baseline to obtain information on perceived stress (Cohen's Perceived Stress Scale) and lifetime history of physician-diagnosed anxiety and/or mood disorders. Female partners were also trained to collect basal saliva samples for the measurement of salivary stress markers, alpha-amylase and cortisol. None. Birth outcome data including infant sex were collected upon delivery. Modified Poisson regression models were used to estimate the relative risks (RRs) of a male birth for each stress marker. After adjusting for potential confounders, we observed a 76% increase in the risk of fathering a male infant (RR 1.76; 95% confidence interval 1.17-2.65) in men diagnosed with anxiety disorders compared with those who were not diagnosed. When lifetime history of physician-diagnosed anxiety disorders was modeled jointly for the couple, the association was slightly strengthened (RR 2.03; 95% confidence interval 1.46-2.84). This prospective cohort study suggests that paternal lifetime history of physician-diagnosed anxiety disorders may be associated with an increase in the secondary sex ratio, resulting in an excess of male births. Copyright © 2016 American Society for Reproductive Medicine. All rights reserved.

  13. Mother's prior intrauterine position affects the sex ratio of her offspring in house mice.

    OpenAIRE

    Vandenbergh, J G; Huggett, C L

    1994-01-01

    Sex ratio alterations related to environmental factors occur in several mammals, but no mechanism has been identified to explain the adjustment. Intrauterine position (IUP) may provide the context in which such alterations occur. Previous studies on house mice and gerbils reveal that the position of a fetus in the uterus in relation to the sex of its neighbors influences its later anatomy, physiology, and behavior. The anogenital distance (AGD) of females located between two males (2M) is lon...

  14. Hormad1 mutation disrupts synaptonemal complex formation, recombination, and chromosome segregation in mammalian meiosis.

    Directory of Open Access Journals (Sweden)

    Yong-Hyun Shin

    2010-11-01

    Full Text Available Meiosis is unique to germ cells and essential for reproduction. During the first meiotic division, homologous chromosomes pair, recombine, and form chiasmata. The homologues connect via axial elements and numerous transverse filaments to form the synaptonemal complex. The synaptonemal complex is a critical component for chromosome pairing, segregation, and recombination. We previously identified a novel germ cell-specific HORMA domain encoding gene, Hormad1, a member of the synaptonemal complex and a mammalian counterpart to the yeast meiotic HORMA domain protein Hop1. Hormad1 is essential for mammalian gametogenesis as knockout male and female mice are infertile. Hormad1 deficient (Hormad1(-/ (- testes exhibit meiotic arrest in the early pachytene stage, and synaptonemal complexes cannot be visualized by electron microscopy. Hormad1 deficiency does not affect localization of other synaptonemal complex proteins, SYCP2 and SYCP3, but disrupts homologous chromosome pairing. Double stranded break formation and early recombination events are disrupted in Hormad1(-/ (- testes and ovaries as shown by the drastic decrease in the γH2AX, DMC1, RAD51, and RPA foci. HORMAD1 co-localizes with γH2AX to the sex body during pachytene. BRCA1, ATR, and γH2AX co-localize to the sex body and participate in meiotic sex chromosome inactivation and transcriptional silencing. Hormad1 deficiency abolishes γH2AX, ATR, and BRCA1 localization to the sex chromosomes and causes transcriptional de-repression on the X chromosome. Unlike testes, Hormad1(-/ (- ovaries have seemingly normal ovarian folliculogenesis after puberty. However, embryos generated from Hormad1(-/ (- oocytes are hyper- and hypodiploid at the 2 cell and 8 cell stage, and they arrest at the blastocyst stage. HORMAD1 is therefore a critical component of the synaptonemal complex that affects synapsis, recombination, and meiotic sex chromosome inactivation and transcriptional silencing.

  15. Sex ratio at birth and racial differences: Why do Black women give ...

    African Journals Online (AJOL)

    The two important questions that this paper will attempt to answer are: (1) why is it that regardless of race/ethnicity or geographic location, the sex ratio data at birth show more males than females?; and (2) Why is it that regardless of geographic location compared to other racial/ethnic groups, Black women or Women of ...

  16. Establishing sex ratios of sea turtle foraging populations: validation of a novel testosterone hormone assay technology and sex assessment for five species.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Demographic data are essential for developing sound management and conservation plans for marine turtle populations. Sex ratios, even though they are an essential...

  17. Guardian small RNAs and sex determination.

    Science.gov (United States)

    Katsuma, Susumu; Kawamoto, Munetaka; Kiuchi, Takashi

    2014-01-01

    The W chromosome of the silkworm Bombyx mori has been known to determine femaleness for more than 80 years. However, the feminizing gene has not been molecularly identified, because the B. mori W chromosome is almost fully occupied by a large number of transposable elements. The W chromosome-derived feminizing factor of B. mori was recently shown to be a female-specific PIWI-interacting RNA (piRNA). piRNAs are small RNAs that potentially repress invading "non-self" elements (e.g., transposons and virus-like elements) by associating with PIWI proteins. Our results revealed that female-specific piRNA precursors, which we named Fem, are transcribed from the sex-determining region of the W chromosome at the early embryonic stage and are processed into a single mature piRNA (Fem piRNA). Fem piRNA forms a complex with Siwi (silkworm Piwi), which cleaves a protein-coding mRNA transcribed from the Z chromosome. RNA interference of this Z-linked gene, which we named Masc, revealed that this gene encodes a protein required for masculinization and dosage compensation. Fem and Masc both participate in the ping-pong cycle of the piRNA amplification loop by associating with the 2 B. mori PIWI proteins Siwi and BmAgo3 (silkworm Ago3), respectively, indicating that the piRNA-mediated interaction between the 2 sex chromosomes is the primary signal for the B. mori sex determination cascade. Fem is a non-transposable repetitive sequence on the W chromosome, whereas Masc is a single-copy protein-coding gene. It is of great interest how the piRNA system recognizes "self "Masc mRNA as "non-self" RNA.

  18. Neurocognitive outcomes of individuals with a sex chromosome trisomy: XXX, XYY, or XXY: a systematic review*

    Science.gov (United States)

    LEGGETT, VICTORIA; JACOBS, PATRICIA; NATION, KATE; SCERIF, GAIA; BISHOP, DOROTHY V M

    2010-01-01

    Aim To review systematically the neurodevelopmental characteristics of individuals with sex chromosome trisomies (SCTs). Method A bibliographic search identified English-language articles on SCTs. The focus was on studies unbiased by clinical referral, with power of at least 0.69 to detect an effect size of 1.0. Results We identified 35 articles on five neonatally identified samples that had adequate power for our review. An additional 11 studies were included where cases had been identified for reasons other than neurodevelopmental concerns. Individuals with an additional X chromosome had mean IQs that were within broadly normal limits but lower than the respective comparison groups, with verbal IQ most affected. Cognitive outcomes were poorest for females with XXX. Males with XYY had normal-range IQs, but all three SCT groups (XXX, XXY, and XYY) had marked difficulties in speech and language, motor skills, and educational achievement. Nevertheless, most adults with SCTs lived independently. Less evidence was available for brain structure and for attention, social, and psychiatric outcomes. Within each group there was much variation. Interpretation Individuals with SCTs are at risk of cognitive and behavioural difficulties. However, the evidence base is slender, and further research is needed to ascertain the nature, severity, and causes of these difficulties in unselected samples. PMID:20059514

  19. Neurocognitive outcomes of individuals with a sex chromosome trisomy: XXX, XYY, or XXY: a systematic review.

    Science.gov (United States)

    Leggett, Victoria; Jacobs, Patricia; Nation, Kate; Scerif, Gaia; Bishop, Dorothy V M

    2010-02-01

    To review systematically the neurodevelopmental characteristics of individuals with sex chromosome trisomies (SCTs). A bibliographic search identified English-language articles on SCTs. The focus was on studies unbiased by clinical referral, with power of at least 0.69 to detect an effect size of 1.0. We identified 35 articles on five neonatally identified samples that had adequate power for our review. An additional 11 studies were included where cases had been identified for reasons other than neurodevelopmental concerns. Individuals with an additional X chromosome had mean IQs that were within broadly normal limits but lower than the respective comparison groups, with verbal IQ most affected. Cognitive outcomes were poorest for females with XXX. Males with XYY had normal-range IQs, but all three SCT groups (XXX, XXY, and XYY) had marked difficulties in speech and language, motor skills, and educational achievement. Nevertheless, most adults with SCTs lived independently. Less evidence was available for brain structure and for attention, social, and psychiatric outcomes. Within each group there was much variation. Individuals with SCTs are at risk of cognitive and behavioural difficulties. However, the evidence base is slender, and further research is needed to ascertain the nature, severity, and causes of these difficulties in unselected samples.

  20. X-Chromosome Control of Genome-Scale Recombination Rates in House Mice.

    Science.gov (United States)

    Dumont, Beth L

    2017-04-01

    Sex differences in recombination are widespread in mammals, but the causes of this pattern are poorly understood. Previously, males from two interfertile subspecies of house mice, Mus musculus musculus and M. m. castaneus , were shown to exhibit a ∼30% difference in their global crossover frequencies. Much of this crossover rate divergence is explained by six autosomal loci and a large-effect locus on the X chromosome. Intriguingly, the allelic effects at this X-linked locus are transgressive, with the allele conferring increased crossover rate being transmitted by the low crossover rate M. m. castaneus parent. Despite the pronounced divergence between males, females from these subspecies exhibit similar crossover rates, raising the question of how recombination is genetically controlled in this sex. Here, I analyze publicly available genotype data from early generations of the Collaborative Cross, an eight-way panel of recombinant inbred strains, to estimate crossover frequencies in female mice with sex-chromosome genotypes of diverse subspecific origins. Consistent with the transgressive influence of the X chromosome in males, I show that females inheriting an M. m. castaneus X possess higher average crossover rates than females lacking the M. m. castaneus X chromosome. The differential inheritance of the X chromosome in males and females provides a simple genetic explanation for sex-limited evolution of this trait. Further, the presence of X-linked and autosomal crossover rate modifiers with antagonistic effects hints at an underlying genetic conflict fueled by selection for distinct crossover rate optima in males and females. Copyright © 2017 by the Genetics Society of America.

  1. Frequency of chromosomal aneuploidy in high quality embryos from young couples using preimplantation genetic screening

    Directory of Open Access Journals (Sweden)

    Farzaneh Fesahat

    2017-09-01

    Full Text Available Background: Selection of the best embryo for transfer is very important in assisted reproductive technology (ART. Using morphological assessment for this selection demonstrated that the correlation between embryo morphology and implantation potential is relatively weak. On the other hand, aneuploidy is a key genetic factor that can influence human reproductive success in ART. Objective: The aim of this lab trial study was to evaluate the incidence of aneuploidies in five chromosomes in the morphologically high-quality embryos from young patients undergoing ART for sex selection. Materials and Methods: A total of 97 high quality embryos from 23 women at the age of 37or younger years that had previously undergone preimplantation genetic screening for sex selection were included in this study. After washing, the slides of blastomeres from embryos of patients were reanalyzed by fluorescence in-situ hybridization for chromosomes 13, 18 and 21. Results: There was a significant rate of aneuploidy determination in the embryos using preimplantation genetic screening for both sex and three evaluated autosomal chromosomes compared to preimplantation genetic screening for only sex chromosomes (62.9% vs. 24.7%, p=0.000. The most frequent detected chromosomal aneuploidy was trisomy or monosomy of chromosome 13. Conclusion: There is considerable numbers of chromosomal abnormalities in embryos generated in vitro which cause in vitro fertilization failure and it seems that morphological characterization of embryos is not a suitable method for choosing the embryos without these abnormalities

  2. Conservation of chromosomes syntenic with avian autosomes in squamate reptiles revealed by comparative chromosome painting

    Czech Academy of Sciences Publication Activity Database

    Pokorná, Martina; Giovannotti, M.; Kratochvíl, L.; Caputo, V.; Olmo, E.; Ferguson-Smith, M. A.; Rens, W.

    2012-01-01

    Roč. 121, č. 4 (2012), s. 409-418 ISSN 0009-5915 R&D Projects: GA ČR GAP506/10/0718 Institutional support: RVO:67985904 Keywords : sex-chromosomes * evolution * genome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.340, year: 2012

  3. Seasonal Sex Ratio Trend in the European Kestrel : An Evolutionarily Stable Strategy Analysis

    NARCIS (Netherlands)

    Pen, I.R.; Weissing, F.J.; Daan, S.

    We present an evolutionarily stable strategy (ESS) model to analyze selection on seasonal variation in the brood sex ratio, as observed in several species of raptorial birds. The model is specifically tailored to the life history of the European kestrel, and it reflects the maturation time

  4. Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio).

    Science.gov (United States)

    Sharma, Prakash; Patiño, Reynaldo

    2013-04-01

    We examined associations between thyroid condition, gonadal sex and pubertal development in zebrafish. Seventy-two-hour postfertilization larvae were reared in untreated medium or in the presence of goitrogens (sodium perchlorate, 0.82 mM; methimazole, 0.15 and 0.3 mM) or thyroxine (1 and 10 nM) for 30 days. Thyrocyte height, gonadal sex and gonadal development were histologically determined at 45 and 60 days postfertilization (dpf). Thyrocyte hypertrophy, an index of hypothyroidism, was observed at 45 and 60 dpf in perchlorate-treated but only at 45 dpf in methimazole-treated fish. Similarly, gonadal sex ratios were biased toward ovaries relative to control animals at 45 and 60 dpf in perchlorate-treated fish but only at 45 dpf in methimazole-treated fish. Gonadal sex ratios were biased toward testes at 45 and 60 dpf in thyroxine-treated fish. Spermatogenesis was delayed in testes from goitrogen-treated fish at 60 dpf relative to control values, but was unaffected in testes from thyroxine-treated individuals. Oogenesis seemed to be nonspecifically delayed in all treatments relative to control at 60 dpf. This study confirmed the previously reported association between hypothyroid condition and ovarian-skewed ratios, and hyperthyroid condition and testicular-skewed ratios, and also showed that male pubertal development is specifically delayed by experimental hypothyroidism. The simultaneous recovery from the hypothyroid and ovary-inducing effects of methimazole by 60 dpf (27 days post-treatment) suggests that the ovary-skewing effect of goitrogens is reversible when thyroid conditions return to basal levels before developmental commitment of gonadal sex. Conversely, the masculinizing effect of hyperthyroidism seems to be stable and perhaps permanent. Published by Elsevier Inc.

  5. Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio)

    Science.gov (United States)

    Sharma, Prakash; Patino, Reynaldo

    2013-01-01

    We examined associations between thyroid condition, gonadal sex and pubertal development in zebrafish. Seventy-two-hour postfertilization larvae were reared in untreated medium or in the presence of goitrogens (sodium perchlorate, 0.82 mM; methimazole, 0.15 and 0.3 mM) or thyroxine (1 and 10 nM) for 30 days. Thyrocyte height, gonadal sex and gonadal development were histologically determined at 45 and 60 days postfertilization (dpf). Thyrocyte hypertrophy, an index of hypothyroidism, was observed at 45 and 60 dpf in perchlorate-treated but only at 45 dpf in methimazole-treated fish. Similarly, gonadal sex ratios were biased toward ovaries relative to control animals at 45 and 60 dpf in perchlorate-treated fish but only at 45 dpf in methimazole-treated fish. Gonadal sex ratios were biased toward testes at 45 and 60 dpf in thyroxine-treated fish. Spermatogenesis was delayed in testes from goitrogen-treated fish at 60 dpf relative to control values, but was unaffected in testes from thyroxine-treated individuals. Oogenesis seemed to be nonspecifically delayed in all treatments relative to control at 60 dpf. This study confirmed the previously reported association between hypothyroid condition and ovarian-skewed ratios, and hyperthyroid condition and testicular-skewed ratios, and also showed that male pubertal development is specifically delayed by experimental hypothyroidism. The simultaneous recovery from the hypothyroid and ovary-inducing effects of methimazole by 60 dpf (27 days post-treatment) suggests that the ovary-skewing effect of goitrogens is reversible when thyroid conditions return to basal levels before developmental commitment of gonadal sex. Conversely, the masculinizing effect of hyperthyroidism seems to be stable and perhaps permanent.

  6. Effects of gamma radiation on development, sterility, fecundity, and sex ratio of Dermanyssus gallinae (DeGeer) (Acari: Dermanyssidae)

    International Nuclear Information System (INIS)

    Entrekin, D.L.; Oliver, J.H. Jr.; Pound, J.M.

    1987-01-01

    Protonymphal Dermanyssus gallinae were irradiated with 0.50, 0.75, 1.0, 3.0, and 6.0 krad of gamma radiation and subsequently monitored regarding their developmental, feeding, and mating success. Also, sex ratios of adults treated as protonymphs were recorded as were sex ratios of embryos and F1 adults produced by these adults. Doses up to 1.0 krad did not prevent development of treated protonymphs to the adult stage or stop mating. Three krad reduced the number of treated protonymphs attaining adulthood and 6.0-krad treatment prevented all mites from developing to the adult stage. Egg (embryo) production was normal for mites treated with 0.50 krad, but significantly curtailed by doses of 0.75 krad and greater. Radiation doses used in this study did not appear to affect the normal variable sex ratios observed in untreated mites

  7. Systematic chromosome examination of two families with schizophrenia and two families with manic depressive illness

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, U.; Mors, O.; Ewald, H. [Aarhus Univ. (Denmark)

    1996-02-16

    Systematic and detailed chromosome analysis, combined with a semistructured interview, was performed in 2 families with schizophrenia and in 2 families with manic depressive illness. Prometaphase technique did not reveal any subtle structural chromosome abnormalities. However, in standard techniques, gain and loss of sex chromosomes were observed. This occurred in patients at a younger age than in unaffected persons. This gives rise to the suspicion that sex chromosome aneuploidy may somehow be related to the development of psychosis. But since the data set is small, especially with respect to schizophrenia, further studies are needed to elucidate this observation. In one family, cosegregation of the disease locus with a marker on chromosome 21 was seen. Therefore, further research should determine if chromosome 21 contains a gene for manic depressive illness. 10 refs., 3 figs., 2 tabs.

  8. Recombination difference between sexes: a role for haploid selection.

    Directory of Open Access Journals (Sweden)

    Thomas Lenormand

    2005-03-01

    Full Text Available Why the autosomal recombination rate differs between female and male meiosis in most species has been a genetic enigma since the early study of meiosis. Some hypotheses have been put forward to explain this widespread phenomenon and, up to now, only one fact has emerged clearly: In species in which meiosis is achiasmate in one sex, it is the heterogametic one. This pattern, known as the Haldane-Huxley rule, is thought to be a side effect, on autosomes, of the suppression of recombination between the sex chromosomes. However, this rule does not hold for heterochiasmate species (i.e., species in which recombination is present in both sexes but varies quantitatively between sexes and does not apply to species lacking sex chromosomes, such as hermaphroditic plants. In this paper, we show that in plants, heterochiasmy is due to a male-female difference in gametic selection and is not influenced by the presence of heteromorphic sex chromosomes. This finding provides strong empirical support in favour of a population genetic explanation for the evolution of heterochiasmy and, more broadly, for the evolution of sex and recombination.

  9. Economics, cultural transmission, and the dynamics of the sex ratio at birth in China.

    Science.gov (United States)

    Lipatov, Mikhail; Li, Shuzhuo; Feldman, Marcus W

    2008-12-09

    In rural China, the ratio of newborn boys to newborn girls [sex ratio at birth (SRB)] has been rising for several decades, to values significantly above its biological norm. This trend has a number of alarming societal consequences, and has attracted the attention of scholars and politicians. The root of the problem lies in a 2,500-year-old culture of son preference. This culture is intricately linked with the economic reality of each couple's life, so that there are financial and psychological repercussions to parents who have no sons. To bring greater clarity and understanding to this issue, we present a quantitative framework that describes the interaction between economics and cultural transmission. We start with an explicit mechanism by which economic incentives can change cultural beliefs of a given individual, and go on to include a mechanism of cultural inheritance from generation to generation. We then show how economic conditions can affect the dynamics of cultural change in an entire society, and may lead to a decrease in the country's sex ratio at birth.

  10. Sex Ratios, Economic Power, and Women's Roles: A Theoretical Extension and Empirical Test.

    Science.gov (United States)

    South, Scott J.

    1988-01-01

    Tested hypotheses concerning sex ratios, women's roles, and economic power with data from 111 countries. Found undersupply of women positively associated with proportion of women who marry and fertility rate; inversely associated with women's average age at marriage, literacy rate, and divorce rate. Suggests women's economic power may counteract…

  11. Mixture Analysis and Mammalian Sex Ratio Among Middle Pleistocene Mouflon of Arago Cave, France

    Science.gov (United States)

    Monchot, Hervé

    1999-09-01

    In archaeological studies, it is often important to be able assess sexual dimorphism and sex ratios in populations. Obtaining sex ratio is easy if each individual in the population can be accurately sexed through the use of one more objective variables. But this is often impossible, due to incompleteness of the osteological record. A modern statistical approach to handle this problem is Mixture Analysis using the method of maximum likelihood. It consists of determining how many groups are present in the sample, two in this case, in which proportions they occur, and to estimate the parameters accordingly. This paper shows the use of this method on vertebrate fossil populations in a prehistoric context with implications on prey acquisition by early humans. For instance, the analysis of mouflon bones from Arago cave (Tautavel, France) indicates that there are more females than males in the F layer. According to the ethology of the animal, this indicates that the hunting strategy could be the result of selective choice of the prey. Moreover, we may deduce the presence of Anteneandertalians on the site during spring and summer periods.

  12. Auger electron spectroscopy for the determination of sex and age related Ca/P ratio at different bone sites

    International Nuclear Information System (INIS)

    Balatsoukas, Ioannis; Kourkoumelis, Nikolaos; Tzaphlidou, Margaret

    2010-01-01

    The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter's Ca/P ratio remains unaffected from all the parameters under study. This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.

  13. Resource Elasticity of Offspring Survival and the Optimal Evolution of Sex Ratios

    Science.gov (United States)

    Wang, Rui-Wu; Wang, Ya-Qiang; He, Jun-Zhou; Li, Yao-Tang

    2013-01-01

    The fitness of any organisms includes the survival and reproductive rate of adults and the survival of their offspring. Environmental selection pressures might not affect these two aspects of an organism equally. Assuming that an organism first allocates its limited resources to maintain its survival under environmental selection pressure, our model, based on the evolutionarily stable strategy theory, surprisingly shows that the sex ratio is greatly affected by the environmental pressure intensity and by the reproductive resource elasticity of offspring survival. Moreover, the concept of the resource elasticity of offspring survival intrinsically integrates the ecological concepts of K selection and r selection. The model shows that in a species with reproductive strategy K, increased environmental selection pressure will reduce resource allocation to the male function. By contrast, in a species with reproductive strategy r, harsher environmental selection pressure will increase allocation to the male function. The elasticity of offspring survival might vary not only across species, but also across many other factors affecting the same species (e.g., age structure, spatial heterogeneity), which explains sex ratio differences across species or age structures and spatial heterogeneity in the same species. PMID:23468826

  14. Using technology, choosing sex. The campaign against sex determination and the question of choice.

    Science.gov (United States)

    1992-01-01

    Women's groups and people's science and health groups formed the Forum Against Sex Determination and Sex Pre-Selection in November 1985 in Bombay, India, to prevent sex determination and sex preselection tests. The Forum considered sex determination and sex preselection to be an abuse of science and technology against people, especially women. Between 1901 and 1991, the sex ratio fell from 972 females/1000 males to 929/1000. The Forum saw the issue of sex determination and sex preselection as a link to oppression of and discrimination against females in all sectors of society. It also believed this to be a human rights issue. The Forum lobbied for a law regulating diagnostic techniques without banning them, since determining chromosomal abnormalities is important. The State of Maharashtra passed such a law in June 1988. It had some provisions which were counter-productive, however. For example, women undergoing a sex determination test must pay a fine of Rs 5 if found guilty of planning to terminate a pregnancy of a female fetus. Yet, neither the husband nor parents-in-law are liable, even though they often pressure women to undergo sex determination tests. The Forum's efforts and enactment of the law in Maharashtra have prompted other state governments and the central government to propose similar legislation. These state governments include Goa, Gujarat, and Orissa. The central government has met with organizations and individuals lobbying against misuse of diagnostic tests to obtain their counsel. The Forum does not feel comfortable with state control, however, since it tends to consider government to be against the people. Yet, the Forum did want the state to protect women's interests. It has raised important questions about technology, particularly concerning criteria to determine desirable and appropriate technologies.

  15. Rumex acetosa Y chromosomes: constitutive or facultative heterochromatin?

    Science.gov (United States)

    Mosiołek, Magdalena; Pasierbek, Paweł; Malarz, Janusz; Moś, Maria; Joachimiak, Andrzej J

    2005-01-01

    Condensed Y chromosomes in Rumex acetosa L. root-tip nuclei were studied using 5-azaC treatment and immunohistochemical detection of methylated histones. Although Y chromosomes were decondensed within root meristem in vivo, they became condensed and heteropycnotic in roots cultured in vitro. 5-azacytidine (5-azaC) treatment of cultured roots caused transitional dispersion of their Y chromosome bodies, but 7 days after removal of the drug from the culture medium, Y heterochromatin recondensed and again became visible. The response of Rumex sex chromatin to 5-azaC was compared with that of condensed segments of pericentromeric heterochromatin in Rhoeo spathacea (Sw.) Steam roots. It was shown that Rhoeo chromocentres, composed of AT-rich constitutive heterochromatin, did not undergo decondensation after 5-azaC treatment. The Y-bodies observed within male nuclei of R. acetosa were globally enriched with H3 histone, demethylated at lysine 4 and methylated at lysine 9. This is the first report of histone tail-modification in condensed sex chromatin in plants. Our results suggest that the interphase condensation of Y chromosomes in Rumex is facultative rather than constitutive. Furthermore, the observed response of Y-bodies to 5-azaC may result indirectly from demethylation and the subsequent altered expression of unknown genes controlling tissue-specific Y-inactivation as opposed to the global demethylation of Y-chromosome DNA.

  16. First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA.

    Directory of Open Access Journals (Sweden)

    Camryn D Allen

    Full Text Available Determining sex ratios of endangered populations is important for wildlife management, particularly species subject to sex-specific threats or that exhibit temperature-dependent sex determination. Sea turtle sex is determined by incubation temperature and individuals lack external sex-based traits until sexual maturity. Previous research utilized serum/plasma testosterone radioimmunoassays (RIA to determine sex in immature/juvenile sea turtles. However, there has been a growing application of enzyme-linked immunosorbent assay (ELISA for wildlife endocrinology studies, but no study on sea turtles has compared the results of ELISA and RIA. This study provides the first sex ratio for a threatened East Pacific green sea turtle (Chelonia mydas foraging aggregation, a critical step for future management of this species. Here, we validate a testosterone ELISA and compare results between RIA and ELISA of duplicate samples. The ELISA demonstrated excellent correspondence with the RIA for providing testosterone concentrations for sex determination. Neither assay proved reliable for predicting the sex of reproductively active females with increased testosterone production. We then applied ELISA to examine the sex ratio of 69 green turtles foraging in San Diego Bay, California. Of 45 immature turtles sampled, sex could not be determined for three turtles because testosterone concentrations fell between the ranges for either sex (females: 4.1-113.1 pg/mL, males: 198.4-2,613.0 pg/mL and these turtles were not subsequently recaptured to enable sex determination; using a Bayesian model to predict probabilities of turtle sex we predicted all three 'unknowns' were female (> 0.86. Additionally, the model assigned all turtles with their correct sex (if determined at recapture with 100% accuracy. Results indicated a female bias (2.83F:1M among all turtles in the aggregation; when focusing only on putative immature turtles the sex ratio was 3.5F:1M. With appropriate

  17. Chimpanzee and human Y chromosomes are remarkably divergent in structure and gene content

    NARCIS (Netherlands)

    Hughes, Jennifer F.; Skaletsky, Helen; Pyntikova, Tatyana; Graves, Tina A.; van Daalen, Saskia K. M.; Minx, Patrick J.; Fulton, Robert S.; McGrath, Sean D.; Locke, Devin P.; Friedman, Cynthia; Trask, Barbara J.; Mardis, Elaine R.; Warren, Wesley C.; Repping, Sjoerd; Rozen, Steve; Wilson, Richard K.; Page, David C.

    2010-01-01

    The human Y chromosome began to evolve from an autosome hundreds of millions of years ago, acquiring a sex-determining function and undergoing a series of inversions that suppressed crossing over with the X chromosome(1,2). Little is known about the recent evolution of the Y chromosome because only

  18. Differential timing and latitudinal variation in sex ratio of Aquatic Warblers during the autumn migration

    Science.gov (United States)

    Wojczulanis-Jakubas, Katarzyna; Chrostek, Małgorzata E.; Jiguet, Frédéric; Martínez, Carlos Zumalacárregui; Miguélez, David; Neto, Júlio M.

    2017-12-01

    Differential migration has been extensively reported in spring, but less so in autumn, particularly in relation to sex in monomorphic bird species. Here, we analysed the autumn passage of a monomorphic, globally threatened passerine, the Aquatic Warbler Acrocephalus paludicola throughout Western Europe, with regard to age and sex. We showed that, overall, adults migrated earlier than first-year birds, and males migrated earlier than females during the autumn migration. This may be caused by an overall social dominance of adults over immatures, and differentiated migration strategy of males and females. In addition, we found male-skewed sex proportions, with a tendency to an equalised ratio in more southern stopover sites. This may indicate a male bias in the global population or different migration strategies of the sexes. Differential migration may cause the age and sex classes to be exposed differently to various threats affecting demographic structure of the species.

  19. Pleiotropic Mechanisms Indicated for Sex Differences in Autism.

    Directory of Open Access Journals (Sweden)

    Ileena Mitra

    2016-11-01

    Full Text Available Sexual dimorphism in common disease is pervasive, including a dramatic male preponderance in autism spectrum disorders (ASDs. Potential genetic explanations include a liability threshold model requiring increased polymorphism risk in females, sex-limited X-chromosome contribution, gene-environment interaction driven by differences in hormonal milieu, risk influenced by genes sex-differentially expressed in early brain development, or contribution from general mechanisms of sexual dimorphism shared with secondary sex characteristics. Utilizing a large single nucleotide polymorphism (SNP dataset, we identify distinct sex-specific genome-wide significant loci. We investigate genetic hypotheses and find no evidence for increased genetic risk load in females, but evidence for sex heterogeneity on the X chromosome, and contribution of sex-heterogeneous SNPs for anthropometric traits to ASD risk. Thus, our results support pleiotropy between secondary sex characteristic determination and ASDs, providing a biological basis for sex differences in ASDs and implicating non brain-limited mechanisms.

  20. seXY: a tool for sex inference from genotype arrays.

    Science.gov (United States)

    Qian, David C; Busam, Jonathan A; Xiao, Xiangjun; O'Mara, Tracy A; Eeles, Rosalind A; Schumacher, Frederick R; Phelan, Catherine M; Amos, Christopher I

    2017-02-15

    Checking concordance between reported sex and genotype-inferred sex is a crucial quality control measure in genome-wide association studies (GWAS). However, limited insights exist regarding the true accuracy of software that infer sex from genotype array data. We present seXY, a logistic regression model trained on both X chromosome heterozygosity and Y chromosome missingness, that consistently demonstrated >99.5% sex inference accuracy in cross-validation for 889 males and 5,361 females enrolled in prostate cancer and ovarian cancer GWAS. Compared to PLINK, one of the most popular tools for sex inference in GWAS that assesses only X chromosome heterozygosity, seXY achieved marginally better male classification and 3% more accurate female classification. https://github.com/Christopher-Amos-Lab/seXY. Christopher.I.Amos@dartmouth.edu. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

  1. A dense SNP-based linkage map for Atlantic salmon (Salmo salar reveals extended chromosome homeologies and striking differences in sex-specific recombination patterns

    Directory of Open Access Journals (Sweden)

    Lien Sigbjørn

    2011-12-01

    Full Text Available Abstract Background The Atlantic salmon genome is in the process of returning to a diploid state after undergoing a whole genome duplication (WGD event between 25 and100 million years ago. Existing data on the proportion of paralogous sequence variants (PSVs, multisite variants (MSVs and other types of complex sequence variation suggest that the rediplodization phase is far from over. The aims of this study were to construct a high density linkage map for Atlantic salmon, to characterize the extent of rediploidization and to improve our understanding of genetic differences between sexes in this species. Results A linkage map for Atlantic salmon comprising 29 chromosomes and 5650 single nucleotide polymorphisms (SNPs was constructed using genotyping data from 3297 fish belonging to 143 families. Of these, 2696 SNPs were generated from ESTs or other gene associated sequences. Homeologous chromosomal regions were identified through the mapping of duplicated SNPs and through the investigation of syntenic relationships between Atlantic salmon and the reference genome sequence of the threespine stickleback (Gasterosteus aculeatus. The sex-specific linkage maps spanned a total of 2402.3 cM in females and 1746.2 cM in males, highlighting a difference in sex specific recombination rate (1.38:1 which is much lower than previously reported in Atlantic salmon. The sexes, however, displayed striking differences in the distribution of recombination sites within linkage groups, with males showing recombination strongly localized to telomeres. Conclusion The map presented here represents a valuable resource for addressing important questions of interest to evolution (the process of re-diploidization, aquaculture and salmonid life history biology and not least as a resource to aid the assembly of the forthcoming Atlantic salmon reference genome sequence.

  2. Phenotypic plasticity in response to the social environment: effects of density and sex ratio on mating behaviour following ecotype divergence.

    Directory of Open Access Journals (Sweden)

    Kristina Karlsson

    Full Text Available The ability to express phenotypically plastic responses to environmental cues might be adaptive in changing environments. We studied phenotypic plasticity in mating behaviour as a response to population density and adult sex ratio in a freshwater isopod (Asellus aquaticus. A. aquaticus has recently diverged into two distinct ecotypes, inhabiting different lake habitats (reed Phragmites australis and stonewort Chara tomentosa, respectively. In field surveys, we found that these habitats differ markedly in isopod population densities and adult sex ratios. These spatially and temporally demographic differences are likely to affect mating behaviour. We performed behavioural experiments using animals from both the ancestral ecotype ("reed" isopods and from the novel ecotype ("stonewort" isopods population. We found that neither ecotype adjusted their behaviour in response to population density. However, the reed ecotype had a higher intrinsic mating propensity across densities. In contrast to the effects of density, we found ecotype differences in plasticity in response to sex ratio. The stonewort ecotype show pronounced phenotypic plasticity in mating propensity to adult sex ratio, whereas the reed ecotype showed a more canalised behaviour with respect to this demographic factor. We suggest that the lower overall mating propensity and the phenotypic plasticity in response to sex ratio have evolved in the novel stonewort ecotype following invasion of the novel habitat. Plasticity in mating behaviour may in turn have effects on the direction and intensity of sexual selection in the stonewort habitat, which may fuel further ecotype divergence.

  3. Live birth sex ratio after in vitro fertilization and embryo transfer in China--an analysis of 121,247 babies from 18 centers.

    Science.gov (United States)

    Bu, Zhiqin; Chen, Zi-Jiang; Huang, Guoning; Zhang, Hanwang; Wu, Qiongfang; Ma, Yanping; Shi, Juanzi; Xu, Yanwen; Zhang, Songying; Zhang, Cuilian; Zhao, Xiaoming; Zhang, Bo; Huang, Yuanhua; Sun, Zhengyi; Kang, Yuefan; Wu, Riran; Wu, Xueqing; Sun, Haixiang; Sun, Yingpu

    2014-01-01

    In order to study the impact of procedures of IVF/ICSI technology on sex ratio in China, we conducted this multi-center retrospective study including 121,247 babies born to 93,895 women in China. There were 62,700 male babies and 58,477 female babies, making the sex ratio being 51.8% (Male: Female  = 107:100). In univariate logistic regression analysis, sex ratio was imbalance toward females of 50.3% when ICSI was preformed compared to 47.7% when IVF was used (Pratio in IVF/ICSI babies was significantly higher toward males in transfers of blastocyst (54.9%) and thawed embryo (52.4%) when compared with transfers of cleavage stage embryo (51.4%) and fresh embryo (51.5%), respectively. Multiple delivery was not associated with sex ratio. However, in multivariable logistic regression analysis after controlling for related factors, only ICSI (adjusted OR =  .90, 95%CI: 0.88-0.93; Pratio in IVF/ICSI babies. In conclusion, the live birth sex ratio in IVF/ICSI babies was influenced by the use of ICSI, which may decrease the percentage of male offspring, or the use of blastocyst transfer, which may increase the percentage of male offspring.

  4. Sex Reversal in Reptiles: Reproductive Oddity or Powerful Driver of Evolutionary Change?

    Science.gov (United States)

    Holleley, Clare E; Sarre, Stephen D; O'Meally, Denis; Georges, Arthur

    2016-01-01

    Is sex a product of genes, the environment, or both? In this review, we describe the diversity of sex-determining mechanisms in reptiles, with a focus on systems that display gene-environment interactions. We summarise the field and laboratory-based evidence for the occurrence of environmental sex reversal in reptiles and ask whether this is a widespread evolutionary mechanism affecting the evolution of sex chromosomes and speciation in vertebrates. Sex determination systems exist across a continuum of genetic and environmental influences, blurring the lines between what was once considered a strict dichotomy between genetic sex determination and temperature-dependent sex determination. Across this spectrum, we identify the potential for sex reversal in species with clearly differentiated heteromorphic sex chromosomes (Pogona vitticeps, Bassiana duperreyi, Eremias multiocellata, Gekko japonicus), weakly differentiated homomorphic sex chromosomes (Niveoscincus ocellatus), and species with only a weak heritable predisposition for sex (Emys orbicularis, Trachemys scripta). We argue that sex reversal is widespread in reptiles (Testudines, Lacertidae, Agamidae, Scincidae, Gekkonidae) and has the potential to have an impact on individual fitness, resulting in reproductively, morphologically, and behaviourally unique phenotypes. Sex reversal is likely to be a powerful evolutionary force responsible for generating and maintaining lability and diversity in reptile sex-determining modes. © 2016 S. Karger AG, Basel.

  5. Sex-biased gene expression in dioecious garden asparagus (Asparagus officinalis).

    Science.gov (United States)

    Harkess, Alex; Mercati, Francesco; Shan, Hong-Yan; Sunseri, Francesco; Falavigna, Agostino; Leebens-Mack, Jim

    2015-08-01

    Sex chromosomes have evolved independently in phylogenetically diverse flowering plant lineages. The genes governing sex determination in dioecious species remain unknown, but theory predicts that the linkage of genes influencing male and female function will spur the origin and early evolution of sex chromosomes. For example, in an XY system, the origin of an active Y may be spurred by the linkage of female suppressing and male promoting genes. Garden asparagus (Asparagus officinalis) serves as a model for plant sex chromosome evolution, given that it has recently evolved an XX/XY sex chromosome system. In order to elucidate the molecular basis of gender differences and sex determination, we used RNA-sequencing (RNA-Seq) to identify differentially expressed genes between female (XX), male (XY) and supermale (YY) individuals. We identified 570 differentially expressed genes, and showed that significantly more genes exhibited male-biased than female-biased expression in garden asparagus. In the context of anther development, we identified genes involved in pollen microspore and tapetum development that were specifically expressed in males and supermales. Comparative analysis of genes in the Arabidopsis thaliana, Zea mays and Oryza sativa anther development pathways shows that anther sterility in females probably occurs through interruption of tapetum development before microspore meiosis. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  6. Next generation sequencing identifies abnormal Y chromosome and candidate causal variants in premature ovarian failure patients.

    Science.gov (United States)

    Lee, Yujung; Kim, Changshin; Park, YoungJoon; Pyun, Jung-A; Kwack, KyuBum

    2016-12-01

    Premature ovarian failure (POF) is characterized by heterogeneous genetic causes such as chromosomal abnormalities and variants in causal genes. Recently, development of techniques made next generation sequencing (NGS) possible to detect genome wide variants including chromosomal abnormalities. Among 37 Korean POF patients, XY karyotype with distal part deletions of Y chromosome, Yp11.32-31 and Yp12 end part, was observed in two patients through NGS. Six deleterious variants in POF genes were also detected which might explain the pathogenesis of POF with abnormalities in the sex chromosomes. Additionally, the two POF patients had no mutation in SRY but three non-synonymous variants were detected in genes regarding sex reversal. These findings suggest candidate causes of POF and sex reversal and show the propriety of NGS to approach the heterogeneous pathogenesis of POF. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Chromosomal location and gene paucity of the male specific region on papaya Y chromosome

    Czech Academy of Sciences Publication Activity Database

    Yu, Q.; Hou, S.; Hobza, Roman; Feltus, F.A.; Wang, X.; Jin, W.; Skelton, R.L.; Blas, A.; Lemke, C.; Saw, J.H.; Moore, P.H.; Alam, M.; Jiang, J.; Paterson, A.H.; Vyskot, Boris; Ming, R.

    2007-01-01

    Roč. 278, č. 2 (2007), s. 177-185 ISSN 1617-4615 R&D Projects: GA ČR(CZ) GA521/06/0056 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : Carica papaya * repetitive sequences * sex chromosome Subject RIV: BO - Biophysics Impact factor: 2.978, year: 2007

  8. Chromosome survey for children of A-bomb survivors

    International Nuclear Information System (INIS)

    Awa, Akio

    1992-01-01

    To investigate chromosomes from children of A-bomb survivors, cytogenetic survey has been started in 1967 by the ABCC and completed in 1985 by the succeeding RERF. This paper is designed to overview the cytogenetic survey and to discuss the cytogenetic effects of A-bomb radiation. A cohort of 16,298 children of A-bomb survivors, which were collected from mortality survey population in 1974, was enrolled in this survey and was divided into two groups: the proximally exposed group (n=8,322, whose parents exposed to estimated doses of 0.01 Gy or more within 2,000 m from the hypocenter) and the distally exposed group (n=7,976, those exposed to 0.005 Gy or less far from 2,500 m or not in the city). Three chromosomal aberrations were identified: sex chromosome aberrations consisting mainly of XYY, XXY, and mosaic; structural abnormality of autosomes consisting mainly of translocation and inversion; and trisomy of autosomes. Overall, the incidence of chromosomal aberrations was higher in the distally exposed group (6.39%) than the proximally exposed group (5.17%). According to the type of chromosomal aberrations, the incidences of both sex chromosomes and structural abnormality of autosomes were slightly higher in the distally exposed group (0.30% and 0.34%) than the proximally exposed group (0.23% and 0.28%). Trisomy of autosomes was identified in only one child in the proximally exposed group. These findings failed to demonstrate the rationale for the cytogenetic effects of A-bomb radiation; however, cytogenetic risk of radiation has not been denied completely. (N.K.)

  9. Mating Frequency and Effects on Sex Ratio in Female Parasitoids of xanthopimpla Stemmator (Thunberg). Implications in biological control Programmes

    International Nuclear Information System (INIS)

    Gitau, C.W.

    2002-01-01

    Cereals, especially maize and sorghum are the most important field crops in Africa. classical biological Control is a management strategy that employs natural enemies against exotic pests on cereal crops. The method has been used against Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), an introduced pest of maize, using the larval parasitoid cotesia flavipes (Cameron). However, C. flavipes is not able to attack all stem borer species in targeted areas. to complement its work, Xanthopimpla stemmator has successfully been established in Mauritius on Chilo sacchariphagus (Bojer). It is a common phenomenon for haplo-diploid parasitoids to give rise to male progeny when insemination does not take place. Mating becomes important to the parasitoid population since a male biased sex ratio can bring about collapse of the population. The aim of this study was to determine wether xanthopimpla stemmator females mat more than once and wether sex ratio of progeny is affected by multiple mating in female X. stemmator. The female showed a tendency to mate once. Multiple mating did not have any significant effect on either sex ratio or longevity. More males were produced in multiple mated females than once mated females.The effect of multiple mating in X. stemmator on sex ratio in relation to biocontrol programmes are discussed

  10. Further observations on sex ratio among infants born to survivors of the atomic bombs, Hiroshima and Nagasaki

    Energy Technology Data Exchange (ETDEWEB)

    Schull, W J; Neel, J V; Hashizume, Asaji

    1965-11-18

    Data are presented on the sex ratio of 47,624 children born in Hiroshima and Nagasaki during 1956 to 1962. The total number of births in these two cities for which information is available is now 140,542, and of this number in 73,994 instances one or both parents were exposed to the atomic bombs. The suggestion of an effect of exposure on sex ratio in the earlier data is not borne out by the present findings. One can argue either that a small early effect has disappeared or that the original observation had no biological significance. 27 references, 4 tables.

  11. Offspring sex ratios in relation to mutual ornamentation and extra-pair paternity in the Black Swan Cygnus atratus

    NARCIS (Netherlands)

    Kraaijeveld, Ken; Ming, Ma; Komdeur, Jan; Mulder, Raoul A.

    In sexually dichromatic birds, females may adaptively adjust the sex ratio of their offspring prior to hatching in relation to male ornamentation, for example, by producing more sons when paired to a highly attractive partner. However, to our knowledge no studies have investigated offspring sex

  12. Calcium availability influences litter size and sex ratio in white-footed mice (Peromyscus leucopus.

    Directory of Open Access Journals (Sweden)

    Christina M Schmidt

    Full Text Available The production of offspring typically requires investment of resources derived from both the environment and maternal somatic reserves. As such, the availability of either of these types of resources has the potential to limit the degree to which resources are allocated to reproduction. Theory and empirical studies have argued that mothers modify reproductive performance relative to exogenous resource availability and maternal condition by adjusting size, number or sex of offspring produced. These relationships have classically been defined relative to availability of energy sources; however, in vertebrates, calcium also plays a critical role in offspring production, as a considerable amount of calcium is required to support the development of offspring skeleton(s. We tested whether the availability of calcium influences reproductive output by providing female white-footed mice with a low-calcium or standard diet from reproductive maturity to senescence. We then compared maternal skeletal condition and reproductive output, based on offspring mass, offspring number and litter sex ratio, between dietary treatments. Mothers on the low-calcium diet exhibited diminished skeletal condition at senescence and produced smaller and strongly female-biased litters. We show that skeletal condition and calcium intake can influence sex ratio and reproductive output following general theoretical models of resource partitioning during reproduction.

  13. Delimiting the origin of a B chromosome by FISH mapping, chromosome painting and DNA sequence analysis in Astyanax paranae (Teleostei, Characiformes.

    Directory of Open Access Journals (Sweden)

    Duílio M Z de A Silva

    Full Text Available Supernumerary (B chromosomes have been shown to contain a wide variety of repetitive sequences. For this reason, fluorescent in situ hybridisation (FISH is a useful tool for ascertaining the origin of these genomic elements, especially when combined with painting from microdissected B chromosomes. In order to investigate the origin of B chromosomes in the fish species Astyanax paranae, these two approaches were used along with PCR amplification of specific DNA sequences obtained from the B chromosomes and its comparison with those residing in the A chromosomes. Remarkably, chromosome painting with the one-arm metacentric B chromosome probe showed hybridization signals on entire B chromosome, while FISH mapping revealed the presence of H1 histone and 18S rDNA genes symmetrically placed in both arms of the B chromosome. These results support the hypothesis that the B chromosome of A. paranae is an isochromosome. Additionally, the chromosome pairs Nos. 2 or 23 are considered the possible B chromosome ancestors since both contain syntenic H1 and 18S rRNA sequences. The analysis of DNA sequence fragments of the histone and rRNA genes obtained from the microdissected B chromosomes showed high similarity with those obtained from 0B individuals, which supports the intraspecific origin of B chromosomes in A. paranae. Finally, the population hereby analysed showed a female-biased B chromosome presence suggesting that B chromosomes in this species could influence sex determinism.

  14. Single-nucleotide variant in multiple copies of a deleted in azoospermia (DAZ) sequence - a human Y chromosome quantitative polymorphism.

    Science.gov (United States)

    Szmulewicz, Martin N; Ruiz, Luis M; Reategui, Erika P; Hussini, Saeed; Herrera, Rene J

    2002-01-01

    The evolution of the deleted in azoospermia (DAZ) gene family supports prevalent theories on the origin and development of sex chromosomes and sexual dimorphism. The ancestral DAZL gene in human chromosome 3 is known to be involved in germline development of both males and females. The available phylogenetic data suggest that some time after the divergence of the New World and Old World monkey lineages, the DAZL gene, which is found in all mammals, was copied to the Y chromosome of an ancestor to the Old World monkeys, but not New World monkeys. In modern man, the Y-linked DAZ gene complex is located on the distal part of the q arm. It is thought that after being copied to the Y chromosome, and after the divergence of the human and great ape lineages, the DAZ gene in the former underwent internal rearrangements. This included tandem duplications as well as a T > C transition altering an MboI restriction enzyme site in a duplicated sequence. In this study, we report on the ratios of MboI-/MboI+ variant sequences in individuals from seven worldwide human populations (Basque, Benin, Egypt, Formosa, Kungurtug, Oman and Rwanda) in the DAZ complex. The ratio of PCR MboI- and MboI+ amplicons can be used to characterize individuals and populations. Our results show a nonrandom distribution of MboI-/MboI+ sequence ratios in all populations examined, as well as significant differences in ratios between populations when compared pairwise. The multiple ratios imply that there have been more than one recent reorganization events at this locus. Considering the dynamic nature of this locus and its involvement in male fertility, we investigated the extent and distribution of this polymorphism. Copyright 2002 S. Karger AG, Basel

  15. A History of the Discovery of Random X Chromosome Inactivation in the Human Female and its Significance

    Directory of Open Access Journals (Sweden)

    Sophia Balderman

    2011-07-01

    Full Text Available Genetic determinants of sex in placental mammals developed by the evolution of primordial autosomes into the male and female sex chromosomes. The Y chromosome determines maleness by the action of the gene SRY, which encodes a protein that initiates a sequence of events prompting the embryonic gonads to develop into testes. The X chromosome in the absence of a Y chromosome results in a female by permitting the conversion of the embryonic gonads into ovaries. We trace the historical progress that resulted in the discovery that one X chromosome in the female is randomly inactivated in early embryogenesis, accomplishing approximate equivalency of X chromosome gene dosage in both sexes. This event results in half of the somatic cells in a tissue containing proteins encoded by the genes of the maternal X chromosome and half having proteins encoded by the genes of the paternal X chromosome, on average, accounting for the phenotype of a female heterozygote with an X chromosome mutation. The hypothesis of X chromosome inactivation as a random event early in embryogenesis was first described as a result of studies of variegated coat color in female mice. Similar results were found in women using the X chromosome-linked gene, glucose-6-phosphate dehydrogenase, studied in red cells. The random inactivation of the X chromosome-bearing genes for isoenzyme types A and B of glucose-6-phosphate dehydrogenase was used to establish the clonal origin of neoplasms in informative women with leiomyomas. Behind these discoveries are the stories of the men and women scientists whose research enlightened these aspects of X chromosome function and their implication for medicine.

  16. Computer-assisted sperm morphometry fluorescence-based analysis has potential to determine progeny sex.

    Science.gov (United States)

    Santolaria, Pilar; Pauciullo, Alfredo; Silvestre, Miguel A; Vicente-Fiel, Sandra; Villanova, Leyre; Pinton, Alain; Viruel, Juan; Sales, Ester; Yániz, Jesús L

    2016-01-01

    This study was designed to determine the ability of computer-assisted sperm morphometry analysis (CASA-Morph) with fluorescence to discriminate between spermatozoa carrying different sex chromosomes from the nuclear morphometrics generated and different statistical procedures in the bovine species. The study was divided into two experiments. The first was to study the morphometric differences between X- and Y-chromosome-bearing spermatozoa (SX and SY, respectively). Spermatozoa from eight bulls were processed to assess simultaneously the sex chromosome by FISH and sperm morphometry by fluorescence-based CASA-Morph. SX cells were larger than SY cells on average (P potential to find differences between X- and Y-chromosome-bearing spermatozoa in bovine species although more studies are needed to increase the precision of sex determination by this technique.

  17. Sex pheromone component ratios and mating isolation among three Lygus plant bug species of North America

    Science.gov (United States)

    Byers, John A.; Fefer, Daniela; Levi-Zada, Anat

    2013-12-01

    The plant bugs Lygus hesperus, Lygus lineolaris, and Lygus elisus (Hemiptera: Miridae) are major pests of many agricultural crops in North America. Previous studies suggested that females release a sex pheromone attractive to males. Other studies showed that males and females contain microgram amounts of ( E)-4-oxo-2-hexenal, hexyl butyrate, and ( E)-2-hexenyl butyrate that are emitted as a defense against predators. Using gas chromatography-mass spectrometry, we found that female L. lineolaris and L. elisus have a 4:10 ratio of hexyl butyrate to ( E)-2-hexenyl butyrate that is reversed from the 10:1 ratio in female L. hesperus (males of the three species have ~10:1 ratio). These reversed ratios among females of the species suggest a behavioral role. Because both sexes have nearly equal amounts of the major volatiles, females should release more to attract males. This expectation was supported because L. hesperus females released more hexyl butyrate (mean of 86 ng/h) during the night (1800-0700 hours) than did males (pheromone component for all three species, ( E)-2-hexenyl butyrate is essential for L. elisus and L. lineolaris, and hexyl butyrate is essential for L. hesperus. However, all three components are recognized by each species since ratios of the butyrate esters are critical for conspecific attraction and heterospecific avoidance by males and thus play a role in reproductive isolation among the three species. Because L. hesperus males and females are known to emit these major volatiles for repelling ant predators, our study links defensive allomones in Lygus bugs with an additional use as sex pheromones.

  18. Rumex acetosa Y chromosomes: constitutive or facultative heterochromatin?

    Directory of Open Access Journals (Sweden)

    Andrzej J. Joachimiak

    2011-08-01

    Full Text Available Condensed Y chromosomes in Rumex acetosa L. root-tip nuclei were studied using 5-azaC treatment and immunohistochemical detection of methylated histones. Although Y chromosomes were decondensed within root meristem in vivo, they became condensed and heteropycnotic in roots cultured in vitro. 5-azacytidine (5-azaC treatment of cultured roots caused transitional dispersion of their Y chromosome bodies, but 7 days after removal of the drug from the culture medium, Y heterochromatin recondensed and again became visible. The response of Rumex sex chromatin to 5-azaC was compared with that of condensed segments of pericentromeric heterochromatin in Rhoeo spathacea (Sw. Stearn roots. It was shown that Rhoeo chromocentres, composed of AT-rich constitutive heterochromatin, did not undergo decondensation after 5-azaC treatment. The Y-bodies observed within male nuclei of R. acetosa were globally enriched with H3 histone, demethylated at lysine 4 and methylated at lysine 9. This is the first report of histone tail-modification in condensed sex chromatin in plants. Our results suggest that the interphase condensation of Y chromosomes in Rumex is facultative rather than constitutive. Furthermore, the observed response of Y-bodies to 5-azaC may result indirectly from demethylation and the subsequent altered expression of unknown genes controlling tissue-specific Y-inactivation as opposed to the global demethylation of Y-chromosome DNA.

  19. Insect Sex Determination Manipulated by Their Endosymbionts: Incidences, Mechanisms and Implications.

    Science.gov (United States)

    Kageyama, Daisuke; Narita, Satoko; Watanabe, Masaya

    2012-02-10

    The sex-determining systems of arthropods are surprisingly diverse. Some species have male or female heterogametic sex chromosomes while other species do not have sex chromosomes. Most species are diploids but some species, including wasps, ants, thrips and mites, are haplodiploids (n in males; 2n in females). Many of the sexual aberrations, such as sexual mosaics, sex-specific lethality and conversion of sexuality, can be explained by developmental defects including double fertilization of a binucleate egg, loss of a sex chromosome or perturbation of sex-determining gene expression, which occur accidentally or are induced by certain environmental conditions. However, recent studies have revealed that such sexual aberrations can be caused by various groups of vertically-transmitted endosymbiotic microbes such as bacteria of the genera Wolbachia, Rickettsia, Arsenophonus, Spiroplasma and Cardinium, as well as microsporidian protists. In this review, we first summarize the accumulated data on endosymbiont-induced sexual aberrations, and then discuss how such endosymbionts affect the developmental system of their hosts and what kinds of ecological and evolutionary effects these endosymbionts have on their host populations.

  20. Complementary sex determination in the parasitic wasp Diachasmimorpha longicaudata.

    Directory of Open Access Journals (Sweden)

    Leonela Carabajal Paladino

    Full Text Available We studied the sex determination in Diachasmimorpha longicaudata, a parasitoid braconid wasp widely used as biological control agent of fruit pest tephritid flies. We tested the complementary sex determination hypothesis (CSD known in at least 60 species of Hymenoptera. According to CSD, male or female development depends on the allelic composition of one sex locus (single-locus CSD or multiple sex loci (multiple-locus CSD. Hemizygote individuals are normal haploid males, and heterozygotes for at least one sex locus are normal diploid females, but homozygotes for all the sex loci are diploid males. In order to force the occurrence of diploid males in D. longicaudata, we established highly inbred lines and examined their offspring using chromosome counting, flow cytometry, and sex ratio analysis. We found that when mother-son crosses were studied, this wasp produced about 20% of diploid males out of the total male progeny. Our results suggest that this parasitoid may represent the second genus with multiple-locus CSD in Hymenoptera. Knowledge about the sex determination system in D. longicaudata is relevant for the improvement of mass rearing protocols of this species. This information also provides the necessary background for further investigations on the underlying molecular mechanisms of sex determination in this species, and a better insight into the evolution of this pathway in Hymenoptera in particular and insects in general.

  1. Analysis of case-parent trios for imprinting effect using a loglinear model with adjustment for sex-of-parent-specific transmission ratio distortion

    DEFF Research Database (Denmark)

    Huang, Lam Opal; Infante-Rivard, Claire; Labbe, Aurélie

    2017-01-01

    Transmission ratio distortion (TRD) is a phenomenon where parental transmission of disease allele to the child does not follow the Mendelian inheritance ratio. TRD occurs in a sex-of-parent-specific or non-sex-of-parent-specific manner. An offset computed from the transmission probability of the ...

  2. Satellite DNA and Transposable Elements in Seabuckthorn (Hippophae rhamnoides), a Dioecious Plant with Small Y and Large X Chromosomes

    Czech Academy of Sciences Publication Activity Database

    Puterová, J.; Razumova, O.; Martínek, T.; Alexandrov, O.; Divashuk, M.; Kubát, Z.; Hobza, Roman; Karlov, G.; Kejnovský, E.

    2017-01-01

    Roč. 9, č. 1 (2017), s. 197-212 ISSN 1759-6653 R&D Projects: GA ČR GBP501/12/G090 Institutional support: RVO:61389030 Keywords : sex-chromosomes * repetitive sequences * silene-latifolia * molecular cytogenetics * arabidopsis-thaliana * genome size * evolution * organization * alignment * database * sex chromosomes * genome composition * chromosomal localization * repetitive DNA Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 3.979, year: 2016

  3. Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio

    Science.gov (United States)

    Dama, Madhukar Shivajirao

    2013-06-01

    Human populations show remarkable variation in the sex ratio at birth which is believed to be related to the parental condition. In the present study, the global variation of sex ratio at birth (SRB, proportion of male offspring born) was analyzed with respect to indirect measure of condition, the intelligence quotient (IQ). IQ correlates strongly with lifespan across nations, which makes it a good indicator of health of the large populations. Relation between three standard measures of average national IQ and SRB was studied using multiple linear regression models. Average national IQ was positively correlated with SRB ( r = 0.54 to 0.57, p difference in general condition of populations.

  4. Commentary Sex determination

    Indian Academy of Sciences (India)

    PRAKASH KUMAR G

    2008-01-31

    Jan 31, 2008 ... years old (Charnier 1966 reported it in an African agamid lizard), although it was ... people's attention in Susumu Ohno's now famous book on .... If they do enhance male and female fitness, sex chromosomes would then be.

  5. MECHANISMS IN ENDOCRINOLOGY: Aberrations of the X chromosome as cause of male infertility.

    Science.gov (United States)

    Röpke, Albrecht; Tüttelmann, Frank

    2017-11-01

    Male infertility is most commonly caused by spermatogenetic failure, clinically noted as oligo- or a-zoospermia. Today, in approximately 20% of azoospermic patients, a causal genetic defect can be identified. The most frequent genetic causes of azoospermia (or severe oligozoospermia) are Klinefelter syndrome (47,XXY), structural chromosomal abnormalities and Y-chromosomal microdeletions. Consistent with Ohno's law, the human X chromosome is the most stable of all the chromosomes, but contrary to Ohno's law, the X chromosome is loaded with regions of acquired, rapidly evolving genes, which are of special interest because they are predominantly expressed in the testis. Therefore, it is not surprising that the X chromosome, considered as the female counterpart of the male-associated Y chromosome, may actually play an essential role in male infertility and sperm production. This is supported by the recent description of a significantly increased copy number variation (CNV) burden on both sex chromosomes in infertile men and point mutations in X-chromosomal genes responsible for male infertility. Thus, the X chromosome seems to be frequently affected in infertile male patients. Four principal X-chromosomal aberrations have been identified so far: (1) aneuploidy of the X chromosome as found in Klinefelter syndrome (47,XXY or mosaicism for additional X chromosomes). (2) Translocations involving the X chromosome, e.g. nonsyndromic 46,XX testicular disorders of sex development (XX-male syndrome) or X-autosome translocations. (3) CNVs affecting the X chromosome. (4) Point mutations disrupting X-chromosomal genes. All these are reviewed herein and assessed concerning their importance for the clinical routine diagnostic workup of the infertile male as well as their potential to shape research on spermatogenic failure in the next years. © 2017 European Society of Endocrinology.

  6. A Newborn with Genital Ambiguity, 45,X/46,XY Mosaicism, a Jumping Chromosome Y, and Congenital Adrenal Hyperplasia

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2013-01-01

    Full Text Available Disorders of sex development (DSD, formerly termed “intersex” conditions, arise from numerous causes. CAH secondary to 21-hydroxylase deficiency is the most common cause of DSD. Sex chromosome disorders, including sex chromosome mosaicism, are the second most common cause of DSD. We discuss a medically complex neonate with DSD presenting with ambiguous genitalia. Hormone levels suggested 21-hydroxylase deficiency. Molecular analysis revealed compound heterozygous mutations in the 21-hydroxylase gene (CYP21A2, confirming the diagnosis of CAH. Chromosome analysis revealed sex chromosome mosaicism with three cell lines: 45,X[8]/45,X,tas(Y;16(p11.32;p13.3[8]/45,X,t(Y;8(p11.32;p23.3[4] with the Y chromosome in telomere association with chromosomes 8p and 16p in different cell lines, a “jumping translocation.” Histologically, the right gonad had irregular, distended seminiferous tubules with hyperplastic germ cells contiguous with ovarian stroma and primordial follicles. The left gonad had scant ovarian stroma and embryonic remnants. Chromosome analyses showed mosaicism in both gonads: 45,X[17]/45,X,tas(Y;8(p11.32;p23.3[3]. This is the first case of coexisting CAH and 45,X/46,XY mosaicism reported in the English literature and the third case of a constitutional chromosome Y “jumping translocation.” Our report documents the medical and genetic complexity of children such as this one with ambiguous genitalia and discusses the need for a multidisciplinary team approach.

  7. Temporal patterns in capture rate and sex ratio of forest bats in Arkansas

    Science.gov (United States)

    Roger W. Perry; S. Andrew Carter; Ronald E. Thill

    2010-01-01

    We quantified changes in capture rates and sex ratios from May to Sept. for eight species of bats, derived from 8 y of extensive mist netting in forests of the Ouachita Mountains, Arkansas. Our primary goal was to determine patterns of relative abundance for each species of bat captured over forest streams and to determine if these patterns were similar to patterns of...

  8. Chromosomal aberrations and micronuclei frequencies in Bulgarian control population

    International Nuclear Information System (INIS)

    Popova, I.; Hadjidekova, V.; Hristova, R.; Atanasova, P.

    2004-01-01

    The aim of this investigation is to represent the frequency of spontaneous chromosomal damages in peripheral blood lymphocytes of Bulgarian control population. Material and methods: The investigated group includes persons belonging to both sexes and different ages. Each of them is interviewed of their social and health status. Sixteen persons are examined using the chromosomal aberrations analysis and forty-five with micronucleus test. The frequency of chromosomal aberrations varied between 0 - 2.4 % and the mean value is 1.00 %. The frequency of cells with micronuclei varied between 4.5 - 24.5 % and the mean value 12,9 %. Further work on the investigation of spontaneous frequency of chromosomal damages is in progress. (authors)

  9. Chromosome-wise dissection of the genome of the extremely big mouse line DU6i.

    Science.gov (United States)

    Bevova, Marianna R; Aulchenko, Yurii S; Aksu, Soner; Renne, Ulla; Brockmann, Gudrun A

    2006-01-01

    The extreme high-body-weight-selected mouse line DU6i is a polygenic model for growth research, harboring many small-effect QTL. We dissected the genome of this line into 19 autosomes and the Y chromosome by the construction of a new panel of chromosome substitution strains (CSS). The DU6i chromosomes were transferred to a DBA/2 mice genetic background by marker-assisted recurrent backcrossing. Mitochondria and the X chromosome were of DBA/2 origin in the backcross. During the construction of these novel strains, >4000 animals were generated, phenotyped, and genotyped. Using these data, we studied the genetic control of variation in body weight and weight gain at 21, 42, and 63 days. The unique data set facilitated the analysis of chromosomal interaction with sex and parent-of-origin effects. All analyzed chromosomes affected body weight and weight gain either directly or in interaction with sex or parent of origin. The effects were age specific, with some chromosomes showing opposite effects at different stages of development.

  10. Impact of repetitive elements on the Y chromosome formation in plants

    Czech Academy of Sciences Publication Activity Database

    Hobza, Roman; Čegan, R.; Jesionek, W.; Kejnovský, E.; Vyskot, B.; Kubát, Z.

    2017-01-01

    Roč. 8, č. 11 (2017), č. článku 302. ISSN 2073-4425 R&D Projects: GA ČR GA16-08698S Institutional support: RVO:61389030 Keywords : Satellites * Sex chromosomes * Transposable elements * Y chromosome Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 3.600, year: 2016

  11. Computer-assisted sperm morphometry fluorescence-based analysis has potential to determine progeny sex

    Directory of Open Access Journals (Sweden)

    Pilar Santolaria

    2016-01-01

    Full Text Available This study was designed to determine the ability of computer-assisted sperm morphometry analysis (CASA-Morph with fluorescence to discriminate between spermatozoa carrying different sex chromosomes from the nuclear morphometrics generated and different statistical procedures in the bovine species. The study was divided into two experiments. The first was to study the morphometric differences between X- and Y-chromosome-bearing spermatozoa (SX and SY, respectively. Spermatozoa from eight bulls were processed to assess simultaneously the sex chromosome by FISH and sperm morphometry by fluorescence-based CASA-Morph. SX cells were larger than SY cells on average (P < 0.001 although with important differences between bulls. A simultaneous evaluation of all the measured features by discriminant analysis revealed that nuclear area and average fluorescence intensity were the variables selected by stepwise discriminant function analysis as the best discriminators between SX and SY. In the second experiment, the sperm nuclear morphometric results from CASA-Morph in nonsexed (mixed SX and SY and sexed (SX semen samples from four bulls were compared. FISH allowed a successful classification of spermatozoa according to their sex chromosome content. X-sexed spermatozoa displayed a larger size and fluorescence intensity than nonsexed spermatozoa (P < 0.05. We conclude that the CASA-Morph fluorescence-based method has the potential to find differences between X- and Y-chromosome-bearing spermatozoa in bovine species although more studies are needed to increase the precision of sex determination by this technique.

  12. Maternal fructose and/or salt intake and reproductive outcome in the rat: effects on growth, fertility, sex ratio, and birth order.

    Science.gov (United States)

    Gray, Clint; Long, Sophie; Green, Charlotte; Gardiner, Sheila M; Craigon, Jim; Gardner, David S

    2013-09-01

    Maternal diet can significantly skew the secondary sex ratio away from the expected value of 0.5 (proportion males), but the details of how diet may do this are unclear. Here, we altered dietary levels of salt (4% salt in the feed) and/or fructose (10% in the drinking water) of pregnant rats to model potential effects that consumption of a "Western diet" might have on maternofetal growth, development, and sex ratio. We demonstrate that excess fructose consumption before and during pregnancy lead to a marked skew in the secondary sex ratio (proportion of males, 0.60; P < 0.006). The effect was not mediated by selective developmental arrest of female embryos or influenced by fetal position in the uterine horn or sex-specific effects on sperm motility, suggesting a direct effect of glycolyzable monosaccharide on the maternal ovary and/or ovulated oocyte. Furthermore, combined excess maternal consumption of salt and fructose-sweetened beverage significantly reduced fertility, reflected as a 50% reduction in preimplantation and term litter size. In addition, we also noted birth order effects in the rat, with sequential implantation sites tending to be occupied by the same sex.

  13. Chromosome Characteristic of Peranakan Etawa (PE) Goat (Capra hircus Linn.) as Indonesian Local Breed

    Science.gov (United States)

    Putri, A. R. I.; Ciptadi, G.; Warih, A. P.

    2018-02-01

    Chromosome characteristics of Peranakan Etawa (PE) goat needs to be analyzed because information about Indonesian goat races is very limited. The purpose of this research was to determine the characteristics of PE goat chromosome as basic data as one of the genetic local resources. Blood was collected from pair of PE goat at Sumber Sekar Field Laboratory, Faculty of Animal Husbandry, Brawijaya University, Malang. Blood cultured using standard cytogenetic technique and stained with G-Banding. Observations being done in metaphase cells and analyzed using Genus Cytovision Image. Chromosomes arranged and numbered by standard goat karyotype. The result of this research showed that PE goat had number of chromosomes 2n=60, consisting of 29 pairs of autosome and a pair of sex chromosomes. Female goat had average of total length (TL) of autosome ranged from 47.91 µm±6.46 to 22.12 µm±3.33. TL of chromosome X are 45.96 µm±4,59 and 44.45 µm±3,96. Centromeric index (Ci) of chromosome X, 31,74 and 32,80. PE goat had average of TL of autosome ranged from 58.20µm±6.72 to 18.97µm±2.82. TL of chromosome X is 56,42µm±7,38 and Y chromosome is 15,80 µm±3,24. Ci in chromosome X and Y are 19.34 and 46.84. These results concluded that the total of goat chromosome was 60 with types of autosomal chromosomes were acrocentric as many as 58 chromosomes and pair of sex chromosomes XX and XY, X classified as subtelocentric and Y submetacentric.

  14. Great tit hatchling sex ratios

    NARCIS (Netherlands)

    Lessells, C.M.; Mateman, A.C.; Visser, J.

    1996-01-01

    The sex of Great Tit Parus major nestlings was determined using PCR RAPDs. Because this technique requires minute amounts of DNA, chicks could be sampled soon (0-2d) after hatching, before any nestling mortality occurred. The proportion of males among 752 chicks hatching in 102 broods (98.9% of

  15. Observation of a ZZW female in a natural population: implications for avian sex determination.

    Science.gov (United States)

    Arit, D; Bensch, S; Hansson, B; Hasselquist, D; Westerdahl, H

    2004-01-01

    Avian sex determination is chromosomal; however, the underlying mechanisms are not yet understood. There is no conclusive evidence for either of two proposed mechanisms: a dominant genetic switch or a dosage mechanism. No dominant sex-determining gene on the female-specific W chromosome has been found. Birds lack inactivation of one of the Z chromosomes in males, but seem to compensate for a double dose of Z-linked genes by other mechanisms. Recent studies showing female-specific expression of two genes may support an active role of the W chromosome. To resolve the question of avian sex determination the investigation of birds with a 2A: ZZW or 2A: ZO genotype would be decisive. Here, we report the case of an apparent 2A: ZZW great reed warbler (Acrocephalus arundinaceus) female breeding in a natural population, which was detected using Z-linked microsatellites. Our data strongly suggest a role of W-linked genes in avian sex determination. PMID:15252998

  16. Sex ratio variation in the bumblebee Bombus terrestris

    DEFF Research Database (Denmark)

    Duchateau, Marie José; Velthuis, Hayo H. W.; Boomsma, Jacobus Jan

    2004-01-01

    Bombus terrestris, bumblebees, colony development, queen control, reproductive strategies, sex allocation......Bombus terrestris, bumblebees, colony development, queen control, reproductive strategies, sex allocation...

  17. Effect of Temperature on Reproduction and Sex Ratio of Guppy (Poecilia reticulata Peters

    Directory of Open Access Journals (Sweden)

    H. Arfah

    2007-01-01

    Full Text Available Water temperature could affect the reproduction of broodstock and sex ratio of progeny.  In this study, broodstock of guppy (Poecilia reticulata Peters was reared in different temperature to determine its effect on reproduction of broodstock and sex ratio of their progeny. The result of study show that broodstock reared at 27°C produced more fry (16 males mean than that of 30°C (10 males, while broodstock reared at 33°C produced no progeny.  Percentage of male fish produced by broodstock reared at 30°C is higher than that of 27°C.  Incubation time of embryo before birth is sorter in broodstock reared at 30°C (4-12 days compared with 27°C (18-22 days.  However, several progeny of broodstock reared at 30°C had abnormal vertebrae. Keywords: guppy, Poecilia reticulata, sex reversal, reproduction, monosex   ABSTRAK Suhu air inkubasi diduga dapat mempengaruhi reproduksi induk ikan dan nisbah kelamin keturunannya.  Pada penelitian ini, induk ikan gapi (Poecilia reticulata Peters dipelihara pada suhu 27°C, 30°C dan suhu 33°C untuk mengetahui pengaruhnya terhadap reproduksi dan rasio kelamin keturunannya.  Hasil penelitian menunjukkan bahwa induk ikan gapi yang dipelihara pada suhu 27°C menghasilkan anak lebih banyak (rata-rata 16 ekor daripada di suhu 30°C (10 ekor, sementara induk gagal melahirkan pada suhu pemeliharaan 33°C. Proporsi anak jantan yang dihasilkan oleh induk yang dipelihara pada suhu 30°C lebih banyak dibandingkan pada suhu 27°C.  Waktu inkubasi embrio sebelum dilahirkan oleh induk yang dipelihara pada suhu 30°C lebih singkat, yaitu 4-12 hari, dibandingkan pada  suhu 27°C, 18-22 hari.  Namun demikian beberapa anak ikan yang lahir dari induk yang dipelihara pada suhu suhu 30°C mengalami abnormalitas pada bagian tulang belakangnya.  Kata kunci: ikan gapi, Poecilia reticulata, sex reversal, reproduksi, monoseks

  18. Delimitation of the embryonic thermosensitive period for sex determination using an embryo growth model reveals a potential bias for sex ratio prediction in turtles.

    Science.gov (United States)

    Girondot, Marc; Monsinjon, Jonathan; Guillon, Jean-Michel

    2018-04-01

    The sexual phenotype of the gonad is dependent on incubation temperature in many turtles, all crocodilians, and some lepidosaurians. At hatching, identification of sexual phenotype is impossible without sacrificing the neonates. For this reason, a general method to infer sexual phenotype from incubation temperatures is needed. Temperature influences sex determination during a specific period of the embryonic development, starting when the gonad begins to form. At constant incubation temperatures, this thermosensitive period for sex determination (TSP) is located at the middle third of incubation duration (MTID). When temperature fluctuates, the position of the thermosensitive period for sex determination can be shifted from the MTID because embryo growth is affected by temperature. A method is proposed to locate the thermosensitive period for sex determination based on modelling the embryo growth, allowing its precise identification from a natural regime of temperatures. Results from natural nests and simulations show that the approximation of the thermosensitive period for sex determination to the middle third of incubation duration may create a quasi-systematic bias to lower temperatures when computing the average incubation temperature during this period and thus a male-bias for sex ratio estimate. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Testosterone has a long-term effect on primary sex ratio of first eggs in pigeons-in search of a mechanism

    NARCIS (Netherlands)

    Goerlich, V. C.; Dijkstra, C.; Schaafsma, S. M.; Groothuis, T. G. G.

    2009-01-01

    Despite accumulating evidence that birds, in which females are the heterogametic sex, are able to manipulate primary offspring sex ratio, the underlying mechanism remains elusive. Steroid hormones. which govern female reproduction and are also accumulated by the developing follicle could potentially

  20. Transitions between sex-determining systems in reptiles and amphibians.

    Science.gov (United States)

    Sarre, Stephen D; Ezaz, Tariq; Georges, Arthur

    2011-01-01

    Important technological advances in genomics are driving a new understanding of the evolution of sex determination in vertebrates. In particular, comparative chromosome mapping in reptiles has shown an intriguing distribution of homology in sex chromosomes across reptile groups. When this new understanding is combined with the widespread distribution of genetic and temperature-dependent sex-determination mechanisms among reptiles, it is apparent that transitions between modes have occurred many times, as they have for amphibians (particularly between male and female heterogamety). It is also likely that thermosensitivity in sex determination is a key factor in those transitions in reptiles, and possibly in amphibians too. New models of sex determination involving temperature thresholds are providing the framework for the investigation of transitions and making possible key predictions about the homologies and sex-determination patterns expected among taxa in these groups. Molecular cytogenetics and other genomic approaches are essential to providing the fundamental material necessary to make advances in this field.