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Sample records for sex gametes apomixis

  1. Sex differences in parental care: Gametic investment, sexual selection, and social environment.

    Science.gov (United States)

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

    2015-11-01

    Male and female parents often provide different type and amount of care to their offspring. Three major drivers have been proposed to explain parental sex roles: (1) differential gametic investment by males and females that precipitates into sex difference in care, (2) different intensity of sexual selection acting on males and females, and (3) biased social environment that facilitates the more common sex to provide more care. Here, we provide the most comprehensive assessment of these hypotheses using detailed parental care data from 792 bird species covering 126 families. We found no evidence for the gametic investment hypothesis: neither gamete sizes nor gamete production by males relative to females was related to sex difference in parental care. However, sexual selection correlated with parental sex roles, because the male share in care relative to female decreased with both extra-pair paternity and frequency of male polygamy. Parental sex roles were also related to social environment, because male parental care increased with male-biased adult sex ratios (ASRs). Taken together, our results are consistent with recent theories suggesting that gametic investment is not tied to parental sex roles, and highlight the importance of both sexual selection and ASR in influencing parental sex roles. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  2. Gamete types, sex determination and stable equilibria of all-hybrid populations of diploid and triploid edible frogs (Pelophylax esculentus

    Directory of Open Access Journals (Sweden)

    Christiansen Ditte G

    2009-06-01

    Full Text Available Abstract Background Triploid individuals often play a key role in speciation by hybridization. An understanding of the gamete types (ploidy and genomic content and stability of hybrid populations with triploid individuals is therefore of importance for exploring the role of hybridization in evolution. The all-hybrid populations of the edible frog, Pelophylax esculentus, are unique in their composition and genetic dynamics: Diploid (genotype LR and triploid (LLR and LRR hybrids depend on each other's different gamete contributions for successful reproduction and maintenance of the populations, as the parental genotypes P. lessonae (LL and P. ridibundus (RR are absent among adults. This study provides data and interpretations on gamete types and sex determination that are essential for understanding the function, evolutionary potential and threats of this intriguing system. Results Dissection of metamorphs from a crossing experiment confirmed that sex determination is an XX-XY system with the Y confined to the L genome. From microsatellite analysis of parents and offspring from the crossings, gamete frequencies could be deduced: Triploids of both sexes mostly made haploid gametes with the genome they had in double dose, however LLR females also made approximately 10% LL gametes by automixis. LR frogs showed much variation in their gamete production. In LRR-rich populations, their LR sperm production was sufficiently high (22% to explain the observed proportion of LRR males, the formation of which has not previously been understood. A model was constructed to calculate equilibrium genotype proportions for different population types on the basis of the gamete proportions found. These equilibria agreed well with empirical literature data. Conclusion If population differentiation with respect to genotype proportions is really driven by gamete patterns, as strongly suggested by the present study, all-hybrid populations constitute not one, but several

  3. Does selection for gamete dispersal and capture lead to a sex difference in clump water-holding capacity?

    Science.gov (United States)

    Moore, Jonathan D; Kollar, Leslie M; McLetchie, D Nicholas

    2016-08-01

    Differences in male and female reproductive function can lead to selection for sex-specific gamete dispersal and capture traits. These traits have been explored from shoot to whole plant levels in wind-pollinated species. While shoot traits have been explored in water-fertilized species, little is known about how whole plant morphology affects gamete dispersal and capture. We used the dioecious, water-fertilized plant Bryum argenteum to test for differences in clump morphology and water-holding characteristics consistent with divergent selection. We hypothesized that sex-specific clump morphology, arising at maturity, produces relatively low male water-holding capacity for gamete dispersal and high female capacity for gamete capture. We measured isolated young shoot and clump water-holding capacity and clump morphological characteristics on greenhouse-grown plants. Young shoot capacity was used to predict clump capacity, which was compared with actual clump capacity. Young male shoots held more water per unit length, and male clumps had higher shoot density, which extrapolated to higher clump water-holding capacity. However, female clumps held more water and were taller with more robust shoots. Actual clump capacity correlated positively with clump height and shoot cross-sectional area. The sex difference in actual clump capacity and its unpredictability from younger shoots are consistent with our hypothesis that males should hold less water than females to facilitate sexual reproduction. These results provide conceptual connections to other plant groups and implications for connecting divergent selection to female-biased sex ratios in B. argenteum and other bryophytes. © 2016 Botanical Society of America.

  4. Transient Activation of Apomixis in Sexual Neotriploids May Retain Genomically Altered States and Enhance Polyploid Establishment

    Directory of Open Access Journals (Sweden)

    Diego Hojsgaard

    2018-02-01

    Full Text Available Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced and rare (unreduced gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid gametes, frequency-dependent disadvantages (minority cytotype exclusion, severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning and drive meiotic (reproductive stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors

  5. Molecular markers linked to apomixis in Panicum maximum Jacq.

    African Journals Online (AJOL)

    SAM

    2014-05-28

    May 28, 2014 ... The objective of this work was to identify molecular markers linked to apomixis in ... Four RAPD markers linked to apomixis were identified and mapped in this .... Data analysis. The amplification of the potential markers was analyzed as binary, with 1 for presence and 0 for absence of the marker. The binary.

  6. An Apomixis-Gene’s View on Dandelions

    NARCIS (Netherlands)

    Dijk, van P.; Jong, de J.H.S.G.M.; Vijverberg, K.; Biere, A.

    2009-01-01

    In asexual organisms, the clone constitutes a level above the individual. Most dandelions (Taraxacum officinale s.l.) reproduce asexually through apomixis, asexual reproduction through seeds. A clone can be seen as a superorganism that is born, that growths, degenerates and eventually dies. Apomixis

  7. Molecular markers linked to apomixis in Panicum maximum Jacq ...

    African Journals Online (AJOL)

    Panicum maximum Jacq. is an important forage grass of African origin largely used in the tropics. The genetic breeding of this species is based on the hybridization of sexual and apomictic genotypes and selection of apomictic F1 hybrids. The objective of this work was to identify molecular markers linked to apomixis in P.

  8. Evolution of the apomixis transmitting chromosome in Pennisetum

    Directory of Open Access Journals (Sweden)

    Yamada-Akiyama Hitomi

    2011-10-01

    Full Text Available Abstract Background Apomixis is an intriguing trait in plants that results in maternal clones through seed reproduction. Apomixis is an elusive, but potentially revolutionary, trait for plant breeding and hybrid seed production. Recent studies arguing that apomicts are not evolutionary dead ends have generated further interest in the evolution of asexual flowering plants. Results In the present study, we investigate karyotypic variation in a single chromosome responsible for transmitting apomixis, the Apospory-Specific Genomic Region carrier chromosome, in relation to species phylogeny in the genera Pennisetum and Cenchrus. A 1 kb region from the 3' end of the ndhF gene and a 900 bp region from trnL-F were sequenced from 12 apomictic and eight sexual species in the genus Pennisetum and allied genus Cenchrus. An 800 bp region from the Apospory-Specific Genomic Region also was sequenced from the 12 apomicts. Molecular cytological analysis was conducted in sixteen Pennisetum and two Cenchrus species. Our results indicate that the Apospory-Specific Genomic Region is shared by all apomictic species while it is absent from all sexual species or cytotypes. Contrary to our previous observations in Pennisetum squamulatum and Cenchrus ciliaris, retrotransposon sequences of the Opie-2-like family were not closely associated with the Apospory-Specific Genomic Region in all apomictic species, suggesting that they may have been accumulated after the Apospory-Specific Genomic Region originated. Conclusions Given that phylogenetic analysis merged Cenchrus and newly investigated Pennisetum species into a single clade containing a terminal cluster of Cenchrus apomicts, the presumed monophyletic origin of Cenchrus is supported. The Apospory-Specific Genomic Region likely preceded speciation in Cenchrus and its lateral transfer through hybridization and subsequent chromosome repatterning may have contributed to further speciation in the two genera.

  9. Evolution of apomixis loci in Pilosella and Hieracium (Asteraceae) inferred from the conservation of apomixis-linked markers in natural and experimental populations

    Science.gov (United States)

    Hand, M L; Vít, P; Krahulcová, A; Johnson, S D; Oelkers, K; Siddons, H; Chrtek, J; Fehrer, J; Koltunow, A M G

    2015-01-01

    The Hieracium and Pilosella (Lactuceae, Asteraceae) genera of closely related hawkweeds contain species with two different modes of gametophytic apomixis (asexual seed formation). Both genera contain polyploid species, and in wild populations, sexual and apomictic species co-exist. Apomixis is known to co-exist with sexuality in apomictic Pilosella individuals, however, apomictic Hieracium have been regarded as obligate apomicts. Here, a developmental analysis of apomixis within 16 Hieracium species revealed meiosis and megaspore tetrad formation in 1 to 7% of ovules, for the first time indicating residual sexuality in this genus. Molecular markers linked to the two independent, dominant loci LOSS OF APOMEIOSIS (LOA) and LOSS OF PARTHENOGENESIS (LOP) controlling apomixis in Pilosella piloselloides subsp. praealta were screened across 20 phenotyped Hieracium individuals from natural populations, and 65 phenotyped Pilosella individuals from natural and experimental cross populations, to examine their conservation, inheritance and association with reproductive modes. All of the tested LOA and LOP-linked markers were absent in the 20 Hieracium samples irrespective of their reproductive mode. Within Pilosella, LOA and LOP-linked markers were essentially absent within the sexual plants, although they were not conserved in all apomictic individuals. Both loci appeared to be inherited independently, and evidence for additional genetic factors influencing quantitative expression of LOA and LOP was obtained. Collectively, these data suggest independent evolution of apomixis in Hieracium and Pilosella and are discussed with respect to current knowledge of the evolution of apomixis. PMID:25026970

  10. Apomixis: Engineering the Ability to Harness Hybrid Vigor in Crop Plants.

    Science.gov (United States)

    Conner, Joann A; Ozias-Akins, Peggy

    2017-01-01

    Apomixis, commonly defined as asexual reproduction through seed, is a reproductive trait that occurs in only a few minor crops, but would be highly valuable in major crops. Apomixis results in seed-derived progenies that are genetically identical to their maternal parent. The advantage of apomixis would lie in seed propagation of elite food, feed, and biofuel crops that are heterozygous such as hybrid corn and switchgrass or self-pollinating crops for which no commercial-scale hybrid production system is available. While hybrid plants often outperform parental lines in growth and higher yields, production of hybrid seed is accomplished through carefully controlled, labor intensive crosses. Both small farmers in developing countries who produce their own seed and commercial companies that market hybrid seed could benefit from the establishment of engineered apomixis in plants. In this chapter, we review what has been learned from studying natural apomicts and mutations in sexual plants leading to apomixis-like development, plus discuss how the components of apomixis could be successfully engineered in plants.

  11. Alternativní zdroje gamet

    Czech Academy of Sciences Publication Activity Database

    Čechová, Dana

    2001-01-01

    Roč. 66, č. 2 (2001), s. 151-152 ISSN 0366-0486 R&D Projects: GA ČR GV524/96/K162 Institutional research plan: CEZ:AV0Z5052915 Keywords : gametes * sperm * eggs Subject RIV: EB - Genetics ; Molecular Biology

  12. Evolution of apomixis loci in Pilosella and Hieracium (Asteraceae) inferred from the conservation of apomixis-linked markers in natural and experimental populations

    Czech Academy of Sciences Publication Activity Database

    Hand, M. L.; Vít, Petr; Krahulcová, Anna; Johnson, S. D.; Oelkers, K.; Siddons, H.; Chrtek, Jindřich; Fehrer, Judith; Koltunow, A. M. G.

    2015-01-01

    Roč. 114, č. 1 (2015), s. 17-26 ISSN 0018-067X R&D Projects: GA ČR GA206/08/0890; GA ČR GAP506/10/1363 Institutional support: RVO:67985939 Keywords : gametophytic apomixis * Hieracium * marker inheritance Subject RIV: EF - Botanics Impact factor: 3.801, year: 2015

  13. Meiosis and Haploid Gametes in the Pathogen Trypanosoma brucei

    OpenAIRE

    Peacock, Lori; Bailey, Mick; Carrington, Mark; Gibson, Wendy

    2014-01-01

    Summary In eukaryote pathogens, sex is an important driving force in spreading genes for drug resistance, pathogenicity, and virulence [1]. For the parasitic trypanosomes that cause African sleeping sickness, mating occurs during transmission by the tsetse vector [2, 3] and involves meiosis [4], but haploid gametes have not yet been identified. Here, we show that meiosis is a normal part of development in the insect salivary glands for all subspecies of Trypanosoma brucei, including the human...

  14. Apomixis is not prevalent in subnival to nival plants of the European Alps

    Czech Academy of Sciences Publication Activity Database

    Hörandl, E.; Dobeš, C.; Suda, Jan; Vít, Petr; Urfus, Tomáš; Temsch, E. M.; Cosendai, A.-C.; Wagner, J.; Ladinig, U.

    2011-01-01

    Roč. 108, č. 2 (2011), s. 381-390 ISSN 0305-7364 Institutional research plan: CEZ:AV0Z60050516 Keywords : apomixis * endosperm * flow cytometric seed screen Subject RIV: EF - Botanics Impact factor: 4.030, year: 2011

  15. New-age ideas about age-old sex: separating meiosis from mating could solve a century-old conundrum.

    Science.gov (United States)

    Brandeis, Michael

    2018-05-01

    Ever since Darwin first addressed it, sexual reproduction reigns as the 'queen' of evolutionary questions. Multiple theories tried to explain how this apparently costly and cumbersome method has become the universal mode of eukaryote reproduction. Most theories stress the adaptive advantages of sex by generating variation, they fail however to explain the ubiquitous persistence of sexual reproduction also where adaptation is not an issue. I argue that the obstacle for comprehending the role of sex stems from the conceptual entanglement of two distinct processes - gamete production by meiosis and gamete fusion by mating (mixis). Meiosis is an ancient, highly rigid and evolutionary conserved process identical and ubiquitous in all eukaryotes. Mating, by contrast, shows tremendous evolutionary variability even in closely related clades and exhibits wonderful ecological adaptability. To appreciate the respective roles of these two processes, which are normally linked and alternating, we require cases where one takes place without the other. Such cases are rather common. The heteromorphic sex chromosomes Y and W, that do not undergo meiotic recombination are an evolutionary test case for demonstrating the role of meiosis. Substantial recent genomic evidence highlights the accelerated rates of change and attrition these chromosomes undergo in comparison to those of recombining autosomes. I thus propose that the most basic role of meiosis is conserving integrity of the genome. A reciprocal case of meiosis without bi-parental mating, is presented by self-fertilization, which is fairly common in flowering plants, as well as most types of apomixis. I argue that deconstructing sex into these two distinct processes - meiosis and mating - will greatly facilitate their analysis and promote our understanding of sexual reproduction. © 2017 Cambridge Philosophical Society.

  16. Surgical treatment of endometriosis before gamete intrafallopian ...

    African Journals Online (AJOL)

    Abstract. Objective. To determine whether active pelvic endometriosis impairs the efficacy of GIFT (gamete intrafallopian transfer) and whether prior surgical treatment of endometriosis improves the efficacy of GIFT. Design. Matched controlled retrospective study. Setting. University-based assisted reproduction programme.

  17. Intra-Family Gamete Donation: A Solution to Concerns Regarding Gamete Donation in China?

    Science.gov (United States)

    Liao, Juhong; Devolder, Katrien

    2016-09-01

    Gamete donation from third parties is controversial in China as it severs blood ties, which are considered of utmost importance in Confucian tradition. In recent years, infertile couples are increasingly demonstrating a preference for the use of gametes donated by family members to conceive children-known as "intra-family gamete donation." The main advantage of intra-family gamete donation is that it maintains blood ties between children and both parents. To date there is no practice of intra-family gamete donation in China. In this paper, we investigate intra-family adoption in China in order to illustrate that intra-family gamete donation is consistent with Confucian tradition regarding the importance of maintaining blood ties within the family. There are several specific ethical issues raised by intra-family gamete donation. It may, for example, result in consanguinity and the semblance of incest, lead to confused family relationships, and raise concerns about possible coercion of familial donors. Confucian tradition provides a new approach to understand and deal with these ethical issues in a way that Western tradition does not. As a result, we suggest intra-family gamete donation could be an acceptable solution to the problem of infertility in China. However, further discussion and open debates on the ethical issues raised by intra-family gamete donation are needed in China.

  18. Oestrogen supplementation in gamete intrafallopian transfer (GIFT ...

    African Journals Online (AJOL)

    Enrique

    2005-02-06

    Feb 6, 2005 ... intrafallopian transfer (GIFT) — a prospective randomised study. ARTICLE. Objective. To investigate the impact of oestrogen supplementation from the early luteal to the late proliferative phase on biochemical and ongoing pregnancy rates in gamete intrafallopian transfer (GIFT). Methods. Ninety-five ...

  19. Negotiating boundaries: Accessing donor gametes in India.

    Science.gov (United States)

    Widge, A; Cleland, J

    2011-01-01

    This paper documents how couples and providers access donor materials for conception in the Indian context and perceptions about using them. The objective is to facilitate understanding of critical issues and relevant concerns. A postal survey was conducted with a sample of 6000 gynaecologists and in-depth interviews were -conducted with 39 gynaecologists in four cities. Donor gametes are relatively more acceptable than a few years ago, especially if confidentiality can be -maintained, though lack of availability of donor materials is sometimes an impediment to infertility treatment. Donor sperms are usually accessed from in-house or commercial sperm banks, pathology laboratories, IVF centres, -professional donors, relatives or friends. There is scepticism about screening procedures of sperm banks. Donor eggs are usually accessed from voluntary donors, friends, relatives, egg sharing programmes, donation from other patients, advertising and commercial donors. There are several concerns regarding informed consent for using donated gametes, using -relatives and friends gametes, the unregulated use of gametes and embryos, record keeping and documentation, -unethical and corrupt practices and commercialisation. These issues need to be addressed by patients, providers and regulatory authorities by providing -information, counselling, ensuring informed consent, addressing exploitation and commercialisation, ensuring -monitoring, proper documentation and transparency.

  20. Potential consequences of clinical application of artificial gametes: a systematic review of stakeholder views.

    Science.gov (United States)

    Hendriks, Saskia; Dondorp, Wybo; de Wert, Guido; Hamer, Geert; Repping, Sjoerd; Dancet, Eline A F

    2015-01-01

    Recent progress in the formation of artificial gametes, i.e. gametes generated from progenitors or somatic cells, has led to scientific and societal discussion about their use in medically assisted reproduction. In animals, live births have already been achieved using artificial gametes of varying (cell type) sources and biological research seems to be progressing steadily toward clinical application in humans. Artificial gametes could potentially help not only infertile heterosexual couples of reproductive age of which one or both partners lacks functional gametes, but also post-menopausal women and same-sex couples, to conceive a child who will be genetically related to them. But as clinical application of these new technologies may have wider societal consequences, a proactive consideration of the possible impact seems timely and important. This review aims to contribute to this by providing a systematic overview of the potential consequences of clinical application of artificial gametes anticipated by different stakeholders. The electronic database 'Medline/Pubmed' was systematically searched with medical subject heading terms (MesH) for articles published in English between January 1970 and December 2013. Articles were selected based on eligibility and reference lists of eligible studies were hand searched. The reported potential consequences of clinical application of artificial gametes were extracted from the articles and were grouped into categories by content analysis. Per category, we noted which stakeholders referred to which potential consequences, based on author affiliations and, if applicable, study participants. The systematic search yielded 2424 articles, and 84 studies were included after screening. Nine positive consequences, 21 specific consequences requiring consideration and 22 recommendations referring to clinical application of artificial gametes were documented. All positive consequences, consequences requiring consideration and

  1. Recombination within the apospory specific genomic region leads to the uncoupling of apomixis components in Cenchrus ciliaris.

    Science.gov (United States)

    Conner, Joann A; Gunawan, Gunawati; Ozias-Akins, Peggy

    2013-07-01

    Apomixis enables the clonal propagation of maternal genotypes through seed. If apomixis could be harnessed via genetic engineering or introgression, it would have a major economic impact for agricultural crops. In the grass species Pennisetum squamulatum and Cenchrus ciliaris (syn. P. ciliare), apomixis is controlled by a single dominant "locus", the apospory-specific genomic region (ASGR). For P. squamulatum, 18 published sequenced characterized amplified region (SCAR) markers have been identified which always co-segregate with apospory. Six of these markers are conserved SCARs in the closely related species, C. ciliaris and co-segregate with the trait. A screen of progeny from a cross of sexual × apomictic C. ciliaris genotypes identified a plant, A8, retaining two of the six ASGR-linked SCAR markers. Additional and newly identified ASGR-linked markers were generated to help identify the extent of recombination within the ASGR. Based on analysis of missing markers, the A8 recombinant plant has lost a significant portion of the ASGR but continues to form aposporous embryo sacs. Seedlings produced from aposporous embryo sacs are 6× in ploidy level and hence the A8 recombinant does not express parthenogenesis. The recombinant A8 plant represents a step forward in reducing the complexity of the ASGR locus to determine the factor(s) required for aposporous embryo sac formation and documents the separation of expression of the two components of apomixis in C. ciliaris.

  2. Social polyandry, parental investment, sexual selection, and evolution of reduced female gamete size.

    Science.gov (United States)

    Andersson, Malte

    2004-01-01

    Sexual selection in the form of sperm competition is a major explanation for small size of male gametes. Can sexual selection in polyandrous species with reversed sex roles also lead to reduced female gamete size? Comparative studies show that egg size in birds tends to decrease as a lineage evolves social polyandry. Here, a quantitative genetic model predicts that female scrambles over mates lead to evolution of reduced female gamete size. Increased female mating success drives the evolution of smaller eggs, which take less time to produce, until balanced by lowered offspring survival. Mean egg size is usually reduced and polyandry increased by increasing sex ratio (male bias) and maximum possible number of mates. Polyandry also increases with the asynchrony (variance) in female breeding start. Opportunity for sexual selection increases with the maximum number of mates but decreases with increasing sex ratio. It is well known that parental investment can affect sexual selection. The model suggests that the influence is mutual: owing to a coevolutionary feedback loop, sexual selection in females also shapes initial parental investment by reducing egg size. Feedback between sexual selection and parental investment may be common.

  3. In Silico and Fluorescence In Situ Hybridization Mapping Reveals Collinearity between the Pennisetum squamulatum Apomixis Carrier-Chromosome and Chromosome 2 of Sorghum and Foxtail Millet

    OpenAIRE

    Sapkota, Sirjan; Conner, Joann A.; Hanna, Wayne W.; Simon, Bindu; Fengler, Kevin; Deschamps, St?phane; Cigan, Mark; Ozias-Akins, Peggy

    2016-01-01

    Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae). The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus) and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass) is the apospory-specific genomic region (ASGR). Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH) a...

  4. Balancing Ethical Pros and Cons of Stem Cell Derived Gametes.

    Science.gov (United States)

    Segers, Seppe; Mertes, Heidi; de Wert, Guido; Dondorp, Wybo; Pennings, Guido

    2017-07-01

    In this review we aim to provide an overview of the most important ethical pros and cons of stem cell derived gametes (SCD-gametes), as a contribution to the debate about reproductive tissue engineering. Derivation of gametes from stem cells holds promising applications both for research and for clinical use in assisted reproduction. We explore the ethical issues connected to gametes derived from embryonic stem cells (both patient specific and non-patient specific) as well as those related to gametes derived from induced pluripotent stem cells. The technology of SCD-gametes raises moral concerns of how reproductive autonomy relates to issues of embryo destruction, safety, access, and applications beyond clinical infertility.

  5. Property rights in human gametes in Australia.

    Science.gov (United States)

    White, Vanessa

    2013-03-01

    It has long been a basic tenet of the common law that there can be no property interest in human bodies or body parts. However, exceptions to the rule have been recognised from the mid-19th century and developed over time. In the early 21st century, there have been interesting developments in the common law of Australia and England, with Australian Supreme Court judges and the English Court of Appeal casting aside existing exceptions, and finding property rights in human body parts, including gametes, by relying instead on a "rational" and "logical" basis to identify property interests in human body parts.

  6. Effects of produced water on gametogenesis and gamete performance in the purple sea urchin (Stronglyocentrotus purpuratus)

    International Nuclear Information System (INIS)

    Krause, P.R.

    1993-01-01

    The author examined the effects of a chronic exposure to produced water (an oil production effluent) discharge on the gametogenesis and gamete performance of the purple sea urchin (Strongylocentrotus purpuratus) using an in situ caging experiment. Adult purple urchins were kept in benthic cages arrayed down-field from a discharging diffuser at 13 sites with distances ranging from 5m to 1,000m. Cage exposures were maintained in the field for eight weeks and each cage held 25 urchins. Gametogenesis was examined for each sex by comparing a size-independent measure of gonad mass as determined by analysis of covariance. The author found that there was a significant negative relationship between gonad mass and cage distance for both sexes, indicating that urchins living closer to the outfall produced significantly larger gonads. Gamete performance was measured through a fertilization kinetic bioassay that holds the concentration of eggs constant and varies the amount of sperm added. The proportion of eggs fertilized under each sperm concentration was determined and the response fit to a kinetics model. Significant differences were found in the fertilizability of eggs between cages. This showed a positive relationship with distance away from the outfall. The findings indicate that while adult urchins exposed to a produced water outfall produced larger gonads, they suffered a marked decreases in gamete performance

  7. Assembly of the Boechera retrofracta Genome and Evolutionary Analysis of Apomixis-Associated Genes

    Directory of Open Access Journals (Sweden)

    Sergei Kliver

    2018-03-01

    Full Text Available Closely related to the model plant Arabidopsis thaliana, the genus Boechera is known to contain both sexual and apomictic species or accessions. Boechera retrofracta is a diploid sexually reproducing species and is thought to be an ancestral parent species of apomictic species. Here we report the de novo assembly of the B. retrofracta genome using short Illumina and Roche reads from 1 paired-end and 3 mate pair libraries. The distribution of 23-mers from the paired end library has indicated a low level of heterozygosity and the presence of detectable duplications and triplications. The genome size was estimated to be equal 227 Mb. N50 of the assembled scaffolds was 2.3 Mb. Using a hybrid approach that combines homology-based and de novo methods 27,048 protein-coding genes were predicted. Also repeats, transfer RNA (tRNA and ribosomal RNA (rRNA genes were annotated. Finally, genes of B. retrofracta and 6 other Brassicaceae species were used for phylogenetic tree reconstruction. In addition, we explored the histidine exonuclease APOLLO locus, related to apomixis in Boechera, and proposed model of its evolution through the series of duplications. An assembled genome of B. retrofracta will help in the challenging assembly of the highly heterozygous genomes of hybrid apomictic species.

  8. Mammalian diversity: gametes, embryos and reproduction.

    Science.gov (United States)

    Behringer, Richard R; Eakin, Guy S; Renfree, Marilyn B

    2006-01-01

    The class Mammalia is composed of approximately 4800 extant species. These mammalian species are divided into three subclasses that include the monotremes, marsupials and eutherians. Monotremes are remarkable because these mammals are born from eggs laid outside of the mother's body. Marsupial mammals have relatively short gestation periods and give birth to highly altricial young that continue a significant amount of 'fetal' development after birth, supported by a highly sophisticated lactation. Less than 10% of mammalian species are monotremes or marsupials, so the great majority of mammals are grouped into the subclass Eutheria, including mouse and human. Mammals exhibit great variety in morphology, physiology and reproduction. In the present article, we highlight some of this remarkable diversity relative to the mouse, one of the most widely used mammalian model organisms, and human. This diversity creates challenges and opportunities for gamete and embryo collection, culture and transfer technologies.

  9. Meiosis and haploid gametes in the pathogen Trypanosoma brucei.

    Science.gov (United States)

    Peacock, Lori; Bailey, Mick; Carrington, Mark; Gibson, Wendy

    2014-01-20

    In eukaryote pathogens, sex is an important driving force in spreading genes for drug resistance, pathogenicity, and virulence. For the parasitic trypanosomes that cause African sleeping sickness, mating occurs during transmission by the tsetse vector and involves meiosis, but haploid gametes have not yet been identified. Here, we show that meiosis is a normal part of development in the insect salivary glands for all subspecies of Trypanosoma brucei, including the human pathogens. By observing insect-derived trypanosomes during the window of peak expression of meiosis-specific genes, we identified promastigote-like (PL) cells that interacted with each other via their flagella and underwent fusion, as visualized by the mixing of cytoplasmic red and green fluorescent proteins. PL cells had a short, wide body, a very long anterior flagellum, and either one or two kinetoplasts, but only the anterior kinetoplast was associated with the flagellum. Measurement of nuclear DNA contents showed that PL cells were haploid relative to diploid metacyclics. Trypanosomes are among the earliest diverging eukaryotes, and our results support the hypothesis that meiosis and sexual reproduction are ubiquitous in eukaryotes and likely to have been early innovations. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Challenge testing of gametes to enhance their viability

    DEFF Research Database (Denmark)

    Callesen, Henrik

    2010-01-01

    of survival mechanism that enables them to come through the process. The details of the mechanism remain unknown but, if identified, it could have immense potential as a new way to improve the viability of embryos produced by ART. However, few publications describe systematic ways to challenge test gametes...... and then to use the results as a basis for improving gamete viability. Furthermore, new methods to monitor the reactions of gametes to such challenge tests are needed. In the present review, these two issues are discussed, as are some of the conditions necessary before a challenge test protocol can be part...

  11. 9 CFR 93.905 - Declaration and other documents for live fish, fertilized eggs, and gametes.

    Science.gov (United States)

    2010-01-01

    ... live fish, fertilized eggs, and gametes. 93.905 Section 93.905 Animals and Animal Products ANIMAL AND... for live fish, fertilized eggs, and gametes. (a) For all live fish, fertilized eggs, and gametes... fish, fertilized eggs, or gametes, the number, species, and the purpose of the importation, the name of...

  12. Chapter 1 Historical Background on Gamete and Embryo Cryopreservation.

    Science.gov (United States)

    Ali, Jaffar; AlHarbi, Naif H; Ali, Nafisa

    2017-01-01

    This chapter describes the development of the science of cryopreservation of gametes and embryos of various species including human. It attempts to record in brief the main contributions of workers in their attempts to cryopreserve gametes and embryos. The initial difficulties faced and subsequent developments and triumphs leading to present-day state of the art are given in a concise manner. The main players and their contributions are mentioned and the authors' aim is to do justice to them. This work also attempts to ensure that credit is correctly attributed for significant advances in gamete and embryo cryopreservation. In general this chapter has tried to describe the historical development of the science of cryopreservation of gametes and embryos as accurately as possible without bias or partiality.

  13. In-vitro Fertilization, Gamete Donation and Surrogacy: Perceptions ...

    African Journals Online (AJOL)

    AJRH Managing Editor

    Most felt surrogates should not be paid. Acceptance ... Keywords: infertility, IVF, gamete donation, surrogacy, Nigeria ... The International Federation of ... of exploiting the surrogate, who is often of a lower ..... Surrogacy Arrangements Act 1985.

  14. Effects of an oil production effluent on gametogenesis and gamete performance in the purple sea urchin (Strongylocentrotus purpuratus Stimpson)

    International Nuclear Information System (INIS)

    Krause, P.R.

    1994-01-01

    Adult organisms subjected to chronic discharges from a point source of pollution may exhibit several sublethal responses. One such response is the impairment of gamete production. This may be expressed in the amount and/or quality of gametes produced by adults. In this study the effects of chronic exposure to produced water (an oil production effluent) on the gametogenesis and gamete performance of the purple sea urchin (Strongylocentrotus purpuratus Stimpson) were examined using an in situ caging experiment. Adult purple sea urchins were kept in benthic cages arrayed down-field from a discharging diffuser at 13 sites, with distances ranging from 5 to 1,000 m. Cage exposures were maintained in the field for eight weeks, and each cage held 25 animals. Gametogenesis was examined for each sex by comparing a size-independent measure of relative gonads ass as determined by analysis of covariance. Results showed that there was a significant negative relationship between these estimates of relative gonad mass and distance from the outfall for both sexes, indicating that sea urchins living closer to the outfall produced significantly larger gonads. Gamete performance was measured through a fertilization kinetics bioassay that held the concentration of eggs constant and varied the amount of sperm added. The proportion of eggs fertilized under each sperm concentration was determined and the response fit to a model of fertilizability showed a positive relationship with distance away from the outfall. These findings indicate that although adult sea urchins exposed to a produced water outfall exhibit larger gonads, they suffer a marked decrease in a gamete performance

  15. Male gametophytic sterility. 1 - Gametic sterilities and deletions in petunia

    Energy Technology Data Exchange (ETDEWEB)

    Cornu, A.; Maizonnier, D. (Station d' Amelioration des Plantes de l' I.N.R.A., Dijon (France))

    1982-01-01

    Terminal deletions induced by ionizing radiations in Petunia are not sexually transmitted. Cytogenetic study of plants with a heterozygous deletion and their progenies shows that this lack of transmission is accompanied by a gametic semi-sterility due to the fact that gametes carrying the deleted chromosome are not viable. The interest of such a male sterility with a gametophytic determinism for the study of sporophyte-gametophyte relationships is underlined.

  16. Consequences on offspring of abnormal function in ageing gametes.

    Science.gov (United States)

    Tarín, J J; Pérez-Albalá, S; Cano, A

    2000-01-01

    The present review aims to analyse (i) the molecular, biochemical and cellular changes that accompany oocyte and sperm ageing in any of the internal or external environments where they can reside, and (ii) the consequences of the abnormal function in ageing gametes on pre- and post-implantation development and later life of offspring. This review also aims to propose and discuss cellular/molecular mechanisms framed within the 'free radical theory of ageing'. It appears that the ageing of gametes prior to fertilization may affect many molecular, biochemical and cellular pathways that may jeopardize not only pre- and post-implantation embryo/fetal development but also later life of offspring. Consequences of gamete ageing range from decreased vigour (with the concomitant decrease in intelligence, reproductive fitness and longevity) of apparently normal-looking offspring to severe congenital, epigenetic and/or genetic anomalies. All these effects may be easily prevented by efficient diffusion of both the potential risks of gamete ageing and the steps that should be taken by couples wishing to achieve pregnancy to guarantee a correct maturational synchronization of gametes at fertilization. Although in-vitro antioxidant therapy appears to protect from or retard the ageing process of gametes, it may not assure the total absence of negative effects on the resulting offspring.

  17. Apomixis y su importancia en la selección y mejoramiento de gramineas forrajeras tropicales. Revisión

    Directory of Open Access Journals (Sweden)

    Adrián R. Quero Carrillo

    2010-01-01

    Hyparrhenia, Melinis, Panicum, Paspalum, Pennisetum, Setaria, Tripsacum y Urochloa, entre otros. Las especies apomícticas contienen individuos diploides y poliploides conformando "complejos agámicos", donde las barreras reproductivas quedan delimitadas por la apomixis y el nivel de ploidía, lo que tiene impacto en su aprovechamiento. Individuos diploides mantienen la sexualidad activa y estos son raros fuera del centro de origen de especie. Los individuos poliploides son apomícticos y los individuos sexuales poliploides pueden inducirse en el laboratorio, lo que permite obtener descendencia híbrida. La riqueza genética, originada del centro de diversidad es la base para superar problemas productivos y de estabilidad ecológica: producción durante la sequía, fijación de nitrógeno, calidad, resistencia a plagas y enfermedades; como se ha demostrado en casos exitosos en Brachiaria, Panicum y Cenchrus. Los avances en investigación sobre apomixis han elucidado su biología y diversas técnicas para su manejo. Sin embargo, el impacto de estos avances en la investigación sobre forrajes en México, promueve la recapitulación sobre el aprovechamiento de recursos genéticos y el interés en la generación de híbridos para las necesidades de producción en pastoreo extensivo en México.

  18. Patterns of genetic variation in Pilosella echioides and its selected relatives: results of variation in ploidy level, facultative apomixis and past and present hybridization

    Czech Academy of Sciences Publication Activity Database

    Chrtek, Jindřich; Plačková, Ivana; Dočkalová, Zuzana; Krahulcová, Anna; Trávníček, Pavel

    2014-01-01

    Roč. 300, č. 9 (2014), s. 2091-2104 ISSN 0378-2697 R&D Projects: GA ČR GAP506/10/1363; GA ČR GP13-18610P Institutional support: RVO:67985939 Keywords : Pilosella * allozymes * apomixis Subject RIV: EF - Botanics Impact factor: 1.422, year: 2014

  19. Expressivity of apomixis in 2n + n hybrids from an apomictic and a sexual parent: insights into variation detected in Pilosella (Asteraceae: Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Krahulec, František; Rosenbaumová, R.

    2011-01-01

    Roč. 24, č. 1 (2011), s. 263-274 ISSN 0934-0882 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : inheritance of apomixis * residual sexuality * unreduced hybrids Subject RIV: EF - Botanics Impact factor: 1.869, year: 2011

  20. [Mobile genetic elements in plant sex evolution].

    Science.gov (United States)

    Gerashchenkov, G A; Rozhnova, N A

    2010-11-01

    The most significant theories of the appearance and maintenance of sex are presented. However, in the overwhelming majority of existing theories, the problem of sex, which is the central problem of evolutionary biology, is considered primarily through the prism of reproductive features of living organisms, whereas the issue of molecular driving forces of sexual reproduction id restricted to the possible role of mobile genetic elements (MGEs) in the appearance of sexual reproduction. The structural and functional significance of MGEs in the genomic organization of plants is illustrated. It is shown that MGEs could act as important molecular drivers of sex evolution in plants. The involvement of MGEs in the formation of sex chromosomes and possible participation in seeds-without-sex reproduction (apomixis) is discussed. Thus, the hypothesis on the active MGE participation in sex evolution is in good agreement with the modern views on pathways and directions of sex evolution in plants.

  1. Mammalian gamete plasma membranes re-assessments and reproductive implications

    Science.gov (United States)

    Establishment of the diploid status occurs with the fusion of female and male gametes. Both the mammalian oocyte and spermatozoa are haploid cells surrounded with plasma membranes that are rich in various proteins playing a crucial role during fertilization. Fertilization is a complex and ordered st...

  2. A Review Of Reproduction And Gamete Management In The African ...

    African Journals Online (AJOL)

    Information on the current status of reproduction and gamete management of the African Catfish, Clarias gariepinus (Burchell) a highly appreciated culturable fish species in Nigeria were reviewed. Natural and artificial reproductive behaviour as well as gonadal maturation rhythm in the highly fecund fish were documented.

  3. Artificial gametes: a systematic review of biological progress towards clinical application

    NARCIS (Netherlands)

    Hendriks, Saskia; Dancet, Eline A. F.; van Pelt, Ans M. M.; Hamer, Geert; Repping, Sjoerd

    2015-01-01

    Recent progress in the formation of artificial gametes, i.e. gametes generated by manipulation of their progenitors or of somatic cells, has led to scientific and societal discussion about their use in medically assisted reproduction (MAR). Artificial gametes could potentially help infertile men and

  4. 9 CFR 93.903 - Import permits for live fish, fertilized eggs, and gametes.

    Science.gov (United States)

    2010-01-01

    ..., fertilized eggs, and gametes. 93.903 Section 93.903 Animals and Animal Products ANIMAL AND PLANT HEALTH... General Provisions for Svc-Regulated Fish Species § 93.903 Import permits for live fish, fertilized eggs, and gametes. (a) Live fish, fertilized eggs, or gametes of SVC-susceptible species imported into the...

  5. Rna synthesis of perinatal female and male gametes

    International Nuclear Information System (INIS)

    Doering, R.; Hubaleck, K.

    1980-01-01

    Intensity curves of RNA synthesis in the perinatal phase of gametogenesis were established for rat fetuses and young rats by 3 H-uridine autoradiography. Gonads of male and female rat fetuses were studied on days 15 to 22 p.c. and gonads of young animals on days 1 to 7 p.n. The nuclear surface of the gametes was found to increase continuously. The number of silver grains was the same for male and female gametes up to the 18th day of fetal life, and the same applies to the silver grain density. The rate of RNA synthesis of male germ celles remained at a constant, low level throughout the study; in the female germ cells, a 10-fold increase in RNA synthesis was measured after the 19th day of fetal life. (orig./MG) [de

  6. Stem cells to gametes: how far should we go?

    Science.gov (United States)

    Whittaker, Peter

    2007-03-01

    Murine embryonic stem cells have recently been shown to be capable of differentiating in vitro into oocytes or sperm. Should these findings be duplicated using human embryonic stem cells, this would raise a number of social and ethical concerns, some specific to these particular developments, others shared with other aspects of stem cell research. This review outlines the properties of stem cells and their conversion to gametes. Concerns raised include embryo destruction, quality of gametes derived in this way, possibility for children with two male biological parents, movement towards germ line gene therapy and 'designer babies', and the future impacts on health service provisions. It is important that public discussion of some of these issues should take place.

  7. Motile male gametes of the araphid diatom Tabularia fasciculata search randomly for mates.

    Directory of Open Access Journals (Sweden)

    Robyn Edgar

    Full Text Available Sexuality in the marine araphid diatom Tabularia involves an unusual type of gamete, not only among diatoms but possibly in all of nature. The non-flagellated male gamete is free and vigorously motile, propelled by pseudopodia. However, the cues (if any in their search for compatible female gametes and the general search patterns to locate them are unknown. We tracked and compared male gamete movements in the presence and absence of receptive female gametes. Path linearity of male movement was not affected by presence of female gametes. Male gametes did not move towards female gametes regardless of their proximity to each other, suggesting that the detection range for a compatible mate is very small compared to known algal examples (mostly spermatozoids and that mate recognition requires (near contact with a female gamete. We therefore investigated how male gametes move to bring insight into their search strategy and found that it was consistent with the predictions of a random-walk model with changes in direction coming from an even distribution. We further investigated the type of random walk by determining the best-fit distribution on the tail of the move length distribution and found it to be consistent with a truncated power law distribution with an exponent of 2.34. Although consistent with a Lévy walk search pattern, the range of move lengths in the tail was too narrow for Lévy properties to emerge and so would be best described as Brownian motion. This is somewhat surprising because female gametes were often outnumbered by male gametes, thus contrary to the assumption that a Brownian search mode may be most optimal with an abundant target resource. This is also the first mathematically analysed search pattern of a non-flagellated protistan gamete, supporting the notion that principles of Brownian motion have wide application in biology.

  8. Two neutral alleles of improving male gamete abortion in indica-japonica hybrid rice

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@It was difficult to use the pronounced heterosis of indica-japonica hybrids rice due to the panicle sterility caused by male and female gamete abortion. The female gamete abortion in most of subspecific hybrids could be solved by using an abortion-neutral gene S5-n, a wide compatibility gene. The problem of male gamete abortion indicated by distorted segregation of marker genes remained to be studied. Segregation distortion via male gamete had been reported on chromosomes 3, 7, 8, 11, and 12.

  9. Syncytin-1 and its receptor is present in human gametes

    DEFF Research Database (Denmark)

    Bjerregaard, B; Lemmen, J G; Petersen, M R

    2014-01-01

    and around the equatorial segment. The receptor ASCT-2 is expressed in the acrosomal region and in the sperm tail. Moreover, ASCT-2, but not syncytin-1, is expressed in oocytes and the mRNA level increases with increasing maturity of the oocytes. CONCLUSIONS: Syncytin and its receptor are present in human......MAIN PURPOSE AND RESEARCH QUESTION: To determine whether the true fusogen Syncytin-1 and its receptor (ASCT-2) is present in human gametes using qRT-PCR, immunoblotting and immunofluorescence. METHODS: Donated oocytes and spermatozoa, originating from a fertility center in tertiary referral...

  10. Postmating sexual conflict and female control over fertilization during gamete interaction.

    Science.gov (United States)

    Firman, Renée C

    2018-06-01

    Males and females rarely have identical evolutionary interests over reproduction, and when the fitness of both sexes is dependent upon paternity outcomes, sexual conflict over fertilization is inevitable. In internal fertilizers, the female tract is a formidable selective force on the number and integrity of sperm that reach the egg. Selection on sperm quality is intensified when females mate multiply and rival males are forced to compete for fertilizations. While male adaptations to sperm competition have been well documented (e.g., increased sperm fertilizing capacity), much less attention has been given to the evolutionary consequences of postmating sexual conflict for egg form and function. Specifically, increased sperm competitiveness can be detrimental by giving rise to an elevation in reproductive failure resulting from polyspermy. Spanning literature on both internal and external fertilizers, in this review I discuss how females respond to sperm competition via fertilization barriers that mediate sperm entry. These findings, which align directly with sexual conflict theory, indicate that females have greater control over fertilization than has previously been appreciated. I then consider the implications of gametic sexual conflict in relation to the development of reproductive isolation and speculate on potential mechanisms accounting for "egg defensiveness." Finally, I discuss the functional significance of egg defensiveness for both the sexes, and sperm selection for females. © 2018 New York Academy of Sciences.

  11. Is vitronectin the velcro that binds the gametes together?

    Science.gov (United States)

    Fusi, F M; Bernocchi, N; Ferrari, A; Bronson, R A

    1996-11-01

    Evidence has been presented that the adhesion of human spermatozoa to the oolemma is mediated by integrins recognizing the Arg-Gly-Asp sequence (RGD). Fibronectin and vitronectin, glycoproteins that contain functional RGD sequences, are both present on human spermatozoa, and integrins that recognize these ligands have been detected on spermatozoa and eggs. In this work, we studied the effects of oligopeptides specifically designed to block fibronectin or vitronectin receptors on the interaction of human spermatozoa with zona-free hamster oocytes. GRGDdSP, a peptide blocking cell attachment to fibronectin, was without effect, while GdRGDSP, which blocks both fibronectin and vitronectin receptors, significantly inhibited the binding of human spermatozoa to the oolemma of zona-free hamster eggs, in a concentration-dependent manner, over a range 1-100 microM. As these experiments suggested that a vitronectin receptor plays a role in sperm-oolemmal adhesion, we performed a series of experiments studying the effects of exogenous vitronectin, when added to spermatozoa and oocytes, on gamete interactions. Sperm-oolemmal adherence, as well as sperm aggregation, was promoted by vitronectin, over range of 2.2 nM to 1 microM, but only in the presence of calcium ions. We propose that vitronectin released during the sperm acrosome reaction is recognized by both gametes and plays a role in their adhesion.

  12. Evolution of Gamete Motility Differences I. Relation Between Swimming Speed and Pheromonal Attraction

    NARCIS (Netherlands)

    Hoekstra, Rolf F.; Janz, Robert F.; Schilstra, A.J.

    1984-01-01

    An analysis is made using population genetic models of the evolution of gamete motility differences as a consequence of a pheromonal gametic approach mechanism. A stable swimming speed dimorphism may arise via disruptive selection on swimming speed, resulting from selection favouring a high

  13. Three members of the 6-cys protein family of Plasmodium play a role in gamete fertility.

    NARCIS (Netherlands)

    Dijk, M.R. van; Schaijk, B.C.L. van; Khan, S.M.; Dooren, M.W. van; Ramesar, J.; Kaczanowski, S.; Gemert, G.J.A. van; Kroeze, H.; Stunnenberg, H.G.; Eling, W.M.C.; Sauerwein, R.W.; Waters, A.P.; Janse, C.J.

    2010-01-01

    The process of fertilization is critically dependent on the mutual recognition of gametes and in Plasmodium, the male gamete surface protein P48/45 is vital to this process. This protein belongs to a family of 10 structurally related proteins, the so called 6-cys family. To identify the role of

  14. In Silico and Fluorescence In Situ Hybridization Mapping Reveals Collinearity between the Pennisetum squamulatum Apomixis Carrier-Chromosome and Chromosome 2 of Sorghum and Foxtail Millet.

    Directory of Open Access Journals (Sweden)

    Sirjan Sapkota

    Full Text Available Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae. The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass is the apospory-specific genomic region (ASGR. Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH and varied in both karyotype and position of the ASGR on the ASGR-carrier chromosome among other apomictic Cenchrus/Pennisetum species. Using in silico transcript mapping and verification of physical positions of some of the transcripts via FISH, we discovered that the ASGR-carrier chromosome from P. squamulatum is collinear with chromosome 2 of foxtail millet and sorghum outside of the ASGR. The in silico ordering of the ASGR-carrier chromosome markers, previously unmapped in P. squamulatum, allowed for the identification of a backcross line with structural changes to the P. squamulatum ASGR-carrier chromosome derived from gamma irradiated pollen.

  15. In Silico and Fluorescence In Situ Hybridization Mapping Reveals Collinearity between the Pennisetum squamulatum Apomixis Carrier-Chromosome and Chromosome 2 of Sorghum and Foxtail Millet.

    Science.gov (United States)

    Sapkota, Sirjan; Conner, Joann A; Hanna, Wayne W; Simon, Bindu; Fengler, Kevin; Deschamps, Stéphane; Cigan, Mark; Ozias-Akins, Peggy

    2016-01-01

    Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae). The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus) and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass) is the apospory-specific genomic region (ASGR). Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH) and varied in both karyotype and position of the ASGR on the ASGR-carrier chromosome among other apomictic Cenchrus/Pennisetum species. Using in silico transcript mapping and verification of physical positions of some of the transcripts via FISH, we discovered that the ASGR-carrier chromosome from P. squamulatum is collinear with chromosome 2 of foxtail millet and sorghum outside of the ASGR. The in silico ordering of the ASGR-carrier chromosome markers, previously unmapped in P. squamulatum, allowed for the identification of a backcross line with structural changes to the P. squamulatum ASGR-carrier chromosome derived from gamma irradiated pollen.

  16. Recent microfluidic devices for studying gamete and embryo biomechanics.

    Science.gov (United States)

    Lai, David; Takayama, Shuichi; Smith, Gary D

    2015-06-25

    The technical challenges of biomechanic research such as single cell analysis at a high monetary cost, labor, and time for just a small number of measurements is a good match to the strengths of microfluidic devices. New scientific discoveries in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of clinical practice in assisted reproduction. The following review will highlight some recent microfluidic devices tailored for gamete and embryo biomechanics where biomimicry arises as a major theme of microfluidic device design and function, and the application of fundamental biomechanic principles are used to improve outcomes of cryopreservation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. 9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.

    Science.gov (United States)

    2010-01-01

    ... of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals and Animal Products ANIMAL... importation of live fish, fertilized eggs, and gametes. (a) The following ports are designated as ports of entry for live fish, fertilized eggs, and gametes of SVC-susceptible species imported under this subpart...

  18. The impact of disclosure on donor gamete participants: donors, intended parents and offspring.

    Science.gov (United States)

    Greenfeld, Dorothy A

    2008-06-01

    The present review examines recent publications that provide insight into how the trend toward nonanonymity and disclosure in gamete donation impacts donors, intended parents, and their donor-conceived children. Recent findings show an increase in donor programs that offer open-identity between donors and offspring. The psychological needs of gamete donors and their attitudes toward disclosure are increasingly given consideration. Qualitative research on how parents of donor gamete offspring make decisions about disclosure reveals that even when couples initially disagree about disclosing to offspring, most ultimately come to a united disclosure decision. The literature on the impact of disclosure on donor gamete offspring has extended to include children conceived through embryo donation and children born as a result of surrogacy. The absence of genetic or gestational link between parents and their child does not have a negative impact on parent-child relationships. Parents through surrogacy tend to disclose the method of family creation to their child, whereas parents through embryo donation tend to be secretive about their child's origins. The trend toward greater openness in gamete donation has been accompanied by an increase in programs offering open-identity donation. In addition, the psychological needs of gamete donors and their attitudes toward disclosure are increasingly being given consideration. Parents of donor gamete offspring give careful thought to their disclosure decisions, and the psychological well being of donor-conceived children does not seem to be impacted by those decisions.

  19. [Gamete donation contracts: gift of life or sale of genetic material?].

    Science.gov (United States)

    Raposo, Vera Lúcia

    2012-01-01

    When science made possible to overcome the biological limitation to infertility, gamete had become a "valuable good". Therefore, lawyers are asked to define their juridical status, their modality of transference, their possible uses and the legal protection reserved to them.

  20. Epigenetic effects of methoxychlor and vinclozolin on male gametes.

    Science.gov (United States)

    Paoloni-Giacobino, Ariane

    2014-01-01

    Imprinting is an epigenetic form of gene regulation that mediates a parent-of-origin-dependent expression of the alleles of a number of genes. Imprinting, which occurs at specific sites within or surrounding the gene, called differentially methylated domains, consists in a methylation of CpGs. The appropriate transmission of genomics imprints is essential for the control of embryonic development and fetal growth. A number of endocrine disruptors (EDs) affect male reproductive tract development and spermatogenesis. It was postulated that the genetic effects of EDs might be induced by alterations in gene imprinting. We tested two EDs: methoxychlor and vinclozolin. Their administration during gestation induced in the offspring a decrease in sperm counts and significant modifications in the methylation pattern of a selection of paternally and maternally expressed canonical imprinted genes. The observation that imprinting was largely untouched in somatic cells suggests that EDs exert their damaging effects via the process of reprogramming that is unique to gamete development. Interestingly, the effects were transgenerational, although disappearing gradually from F1 to F3. A systematic analysis showed a heterogeneity in the CpG sensitivity to EDs. We propose that the deleterious effects of EDs on the male reproductive system are mediated by imprinting defects in the sperm. The reported effects of EDs on human male spermatogenesis might be mediated by analogous imprinting alterations. © 2014 Elsevier Inc. All rights reserved.

  1. Keeping mum about dad: "contracts" to protect gamete donor anonymity.

    Science.gov (United States)

    Rees, Anne

    2012-06-01

    This article considers the legal status of so-called contracts for anonymity between fertility clinics and donors of gametes that were made in the period before legislation authorising disclosure. It notes that while clinics frequently cite the existence of these "contracts" to argue against retrospective legislation authorising disclosure of the donor's identity, they may be nothing more than one-sided statements of informed consent. However, the article notes that even if an agreement between a donor and a clinic is not contractual, it does not follow that a person conceived through assisted reproductive technology has any right of access to the identity of the donor. The writer has not been able to locate examples of written promises by the clinics promising anonymity. There are written promises by the donors not to seek the identity of the recipients. These promises do not bind the resulting offspring nor do they appear to be supported by consideration. The article suggests that the basis for any individual donor to restrain a clinic from revealing their identity may be found in promissory estoppel. Nevertheless, there is no real issue in Australia concerning clinics revealing these details absent legislative authority. The issue is whether parliaments will legislate to authorise the disclosure. The article notes that it would be rare for parliaments to legislate to overturn existing legal contracts but suggests that the contract argument may not be as strong as has been thought.

  2. Natural hybridization in the sea urchin genus Pseudoboletia between species without apparent barriers to gamete recognition.

    Science.gov (United States)

    Zigler, Kirk S; Byrne, Maria; Raff, Elizabeth C; Lessios, H A; Raff, Rudolf A

    2012-06-01

    Marine species with high dispersal potential often have huge ranges and minimal population structure. Combined with the paucity of geographic barriers in the oceans, this pattern raises the question as to how speciation occurs in the sea. Over the past 20 years, evidence has accumulated that marine speciation is often linked to the evolution of gamete recognition proteins. Rapid evolution of gamete recognition proteins in gastropods, bivalves, and sea urchins is correlated with gamete incompatibility and contributes to the maintenance of species boundaries between sympatric congeners. Here, we present a counterexample to this general pattern. The sea urchins Pseudoboletia indiana and P. maculata have broad ranges that overlap in the Indian and Pacific oceans. Cytochrome oxidase I sequences indicated that these species are distinct, and their 7.3% divergence suggests that they diverged at least 2 mya. Despite this, we suspected hybridization between them based on the presence of morphologically intermediate individuals in sympatric populations at Sydney, Australia. We assessed the opportunity for hybridization between the two species and found that (1) individuals of the two species occur within a meter of each other in nature, (2) they have overlapping annual reproductive cycles, and (3) their gametes cross-fertilize readily in the laboratory and in the field. We genotyped individuals with intermediate morphology and confirmed that many were hybrids. Hybrids were fertile, and some female hybrids had egg sizes intermediate between the two parental species. Consistent with their high level of gamete compatibility, there is minimal divergence between P. indiana and P. maculata in the gamete recognition protein bindin, with a single fixed amino acid difference between the two species. Pseudoboletia thus provides a well-characterized exception to the idea that broadcast spawning marine species living in sympatry develop and maintain species boundaries through the

  3. The male gametophytic sterility. 1 - Gametic sterilities and deletions in petunia

    International Nuclear Information System (INIS)

    Cornu, A.; Maizonnier, D.

    1982-01-01

    Terminal deletions induced by ionizing radiations in Petunia are not sexually transmitted. Cytogenetic study of plants with a heterozygous deletion and their progenies shows that this lack of transmission is accompanied by a gametic semi-sterility due to the fact that gametes carrying the deleted chromosome are not viable. The interest of such a male sterility with a gametophytic determinism for the study of sporophyte-gametophyte relationships is underlined [fr

  4. Azadirachtin effects on mating success, gametic abnormalities and progeny survival in Drosophila melanogaster (Diptera).

    Science.gov (United States)

    Oulhaci, Chemseddine M; Denis, Béatrice; Kilani-Morakchi, Samira; Sandoz, Jean-Christophe; Kaiser, Laure; Joly, Dominique; Aribi, Nadia

    2018-01-01

    Azadirachtin is a prominent natural pesticide and represents an alternative to conventional insecticides. It has been successfully used against insect pests. However, its effects on reproduction require further analysis. Here we investigated lethal and sublethal effects of azadirachtin, on treated adults in a model insect, Drosophila melanogaster (Meigen). Dose-mortality relationships as well as several parameters of reproduction (mating, spermatogenesis, oogenesis and fertility) were examined. Neem-Azal, a commercial formulation of azadirachtin, applied topically on newly emerged adults, increased mortality with a positive dose-dependent relationship. The LD 50 (0.63 μg) was determined 24 h after treatment using a non-linear regression. Adults surviving this dose had a mating success that was divided by 3 and a progeny production reduced by half when males were treated, and even more when females were treated. When combining probability of survival, of mating and reduced progeny, it appeared that LD 50 induced a 98% reduction in reproductive rates. Reduced progeny was partially explained by the effect of adult treatment on gametes number and abnormalities. The number of cysts and the apical nuclei positions within the cysts decreased by 29.7% and 20%, respectively, in males. In females, the number of oocytes per ovary and the volume of basal oocytes also decreased by 16.1% and 32.4%, respectively. Azadirachtin causes significant toxic effects in both sexes and decreases the fecundity and fertility of D. melanogaster. Females are more sensitive to azadirachtin. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  5. Cytological, molecular mechanisms and temperature stress regulating production of diploid male gametes in Dianthus caryophyllus L.

    Science.gov (United States)

    Zhou, Xuhong; Mo, Xijun; Gui, Min; Wu, Xuewei; Jiang, Yalian; Ma, Lulin; Shi, Ziming; Luo, Ying; Tang, Wenru

    2015-12-01

    In plant evolution, because of its key role in sexual polyploidization or whole genome duplication events, diploid gamete formation is considered as an important component in diversification and speciation. Environmental stress often triggers unreduced gamete production. However, the molecular, cellular mechanisms and adverse temperature regulating diplogamete production in carnation remain poorly understood. Here, we investigate the cytological basis for 2n male gamete formation and describe the isolation and characterization of the first gene, DcPS1 (Dianthus Caryophyllus Parallel Spindle 1). In addition, we analyze influence of temperature stress on diploid gamete formation and transcript levels of DcPS1. Cytological evidence indicated that 2n male gamete formation is attributable to abnormal spindle orientation at male meiosis II. DcPS1 protein is conserved throughout the plant kingdom and carries domains suggestive of a regulatory function. DcPS1 expression analysis show DcPS1 gene probably have a role in 2n pollen formation. Unreduced pollen formation in various cultivation was sensitive to high or low temperature which was probably regulated by the level of DcPS1 transcripts. In a broader perspective, these findings can have potential applications in fundamental polyploidization research and plant breeding programs. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  6. Salmonid Gamete Preservation in the Snake River Basin, Annual Report 2002.

    Energy Technology Data Exchange (ETDEWEB)

    Young, William; Kucera, Paul

    2003-07-01

    In spite of an intensive management effort, chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss) populations in the Northwest have not recovered and are currently listed as threatened species under the Endangered Species Act. In addition to the loss of diversity from stocks that have already gone extinct, decreased genetic diversity resulting from genetic drift and inbreeding is a major concern. Reduced population and genetic variability diminishes the environmental adaptability of individual species and entire ecological communities. The Nez Perce Tribe (NPT), in cooperation with Washington State University and the University of Idaho, established a germplasm repository in 1992 in order to preserve the remaining salmonid diversity in the region. The germplasm repository provides long-term storage for cryopreserved gametes. Although only male gametes can be cryopreserved, conserving the male component of genetic diversity will maintain future management options for species recovery. NPT efforts have focused on preserving salmon and steelhead gametes from the major river subbasins in the Snake River basin. However, the repository is available for all management agencies to contribute gamete samples from other regions and species. In 2002 a total of 570 viable semen samples were added to the germplasm repository. This included the gametes of 287 chinook salmon from the Lostine River, Catherine Creek, upper Grande Ronde River, Imnaha River (Lookingglass Hatchery), Lake Creek, South Fork Salmon River, Johnson Creek, Big Creek, Capehorn Creek, Marsh Creek, Pahsimeroi River (Pahsimeroi Hatchery), and upper Salmon River (Sawtooth Hatchery) and the gametes of 280 steelhead from the North Fork Clearwater River (Dworshak Hatchery), Fish Creek, Little Sheep Creek, Pahsimeroi River (Pahsimeroi Hatchery) and Snake River (Oxbow Hatchery). In addition, gametes from 60 Yakima River spring chinook and 34 Wenatchee River coho salmon were added to the

  7. A central role for P48/45 in malaria parasite male gamete fertility.

    NARCIS (Netherlands)

    Dijk, M.R. van; Janse, C.J.; Thompson, J.; Waters, A.P.; Braks, J.A.M.; Dodemont, H.J.; Stunnenberg, H.G.; Gemert, G.J.A. van; Sauerwein, R.W.; Eling, W.M.C.

    2001-01-01

    Fertilization and zygote development are obligate features of the malaria parasite life cycle and occur during parasite transmission to mosquitoes. The surface protein PFS48/45 is expressed by male and female gametes of Plasmodium falciparum and PFS48/45 antibodies prevent zygote development and

  8. [COMPARATIVE STUDY ON THE SECRET OF THE DONOR'S IDENTITY OF DONATED GAMETES].

    Science.gov (United States)

    Tisseyre, Sandrine

    2015-07-01

    French law lies down a principle of anonymity of donated gametes. This principle is ignored by English law. Moreover, English law has established, few years ago, the contrary principle: the one of transparency of the donor's identity. This study of English law reports this evolution and its consequences.

  9. Couples with non-obstructive azoospermia are interested in future treatments with artificial gametes

    NARCIS (Netherlands)

    Hendriks, S.; Hessel, M.; Mochtar, M. H.; Meissner, A.; van der Veen, F.; Repping, S.; Dancet, E. A. F.

    2016-01-01

    Would couples diagnosed with non-obstructive azoospermia (NOA) consider two future treatments with artificial gametes (AGs) as alternatives for testicular sperm extraction followed by ICSI (TESE-ICSI)? Most couples with NOA (89%) would opt for treatment with AGs before attempting TESE-ICSI and/or

  10. Salmonid Gamete Preservation in the Snake River Basin, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Robyn; Kucera, Paul A. (Nez Perce Tribe, Lapwai, ID)

    1999-03-01

    Steelhead (Oncorhynchus mykiss) and salmon (Oncorhynchus tshawytscha)populations in the Northwest are decreasing. The Nez Perce Tribe (Tribe) was funded in 1998 by the Bonneville Power Administration to coordinate gene banking of male gametes from Endangered Species Act (ESA) listed steelhead and spring and summer chinook salmon in the Snake River basin.

  11. Limitations on the compensation of gamete donors: a public opinion survey.

    Science.gov (United States)

    Lee, Malinda S; Farland, Leslie V; Missmer, Stacey A; Ginsburg, Elizabeth S

    2017-06-01

    To determine public opinion on gamete donor compensation. Cross-sectional web-based survey. Not applicable. A nationally representative sample of 1,427 people in the United States. Not applicable. Support for the compensation of gamete donors. Of 1,427 respondents, 51 (4%) disagreed with use of IVF for any indication, and 232 (16%) believed that oocyte and/or sperm donation to be always unacceptable. Of the remaining 1,185 respondents, 953 (80%) supported and 41 (4%) opposed paying sperm donors; 1,063 (90%) supported and 24 (2%) opposed paying oocyte donors. Of respondents, 90% believed that appropriate compensation for one cycle of oocyte donation should be less than $10,000. A total of 559 (47%) supported a limit on sperm donor compensation and 544 (46%) supported a limit on oocyte donor compensation. Individuals who had personal knowledge of someone with infertility or who used assisted reproductive technology (ART), and Republicans compared with Democrats, were more likely to support limits on both oocyte and sperm donor compensation. Divorced compared with married respondents were less likely to support limits on gamete donor compensation. Men were less likely to support limits on sperm donor compensation. Most respondents in a nationally representative cohort support compensating gamete donors. Although most do not support limits on gamete donor compensation, most agree the appropriate payment for one cycle of oocyte donation is in line with former American Society for Reproductive Medicine guidelines. Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  12. Female parthenogenetic apomixis and androsporogenetic parthenogenesis in embryonal cells of Araucaria angustifolia: interpolation of progenesis and asexual heterospory in an artificial sporangium.

    Science.gov (United States)

    Durzan, Don J

    2012-09-01

    Cell fate, development timing and occurrence of reproductive versus apomictic development in gymnosperms are shown to be influenced by culture conditions in vitro. In this study, female parthenogenetic apomixis (fPA), androsporogenetic parthenogenesis (mAP) and progenesis were demonstrated using embryonal initials of Araucaria angustifolia in scaled-up cell suspensions passing through a single-cell bottleneck in darkness and in an artificial sporangium (AS). Expression was based on defined nutrition, hormones and feedforward-adaptive feedback process controls at 23-25 °C and in darkness. In fPA, the nucleus of an embryonal initial undergoes endomitosis and amitosis, forming a diploid egg-equivalent and an apoptotic ventral canal nucleus in a transdifferentiated archegonial tube. Discharge of egg-equivalent cells as parthenospores and their dispersal into the aqueous culture medium were followed by free-nuclear conifer-type proembryogenesis. This replaced the plesiomorphic and central features of proembryogenesis in Araucariaceae. Protoplasmic fusions of embryonal initials were used to reconstruct heterokaryotic expressions of fPA in multiwell plates. In mAP, restitutional meiosis (automixis) was responsible for androsporogenesis and the discharge of monads, dyads, tetrads and polyads. In a display of progenesis, reproductive development was brought to an earlier ontogenetic stage and expressed by embryonal initials. Colchicine increased polyploidy, but androspore formation became aberrant and fragmented. Aberrant automixis led to the formation of chromosomal bouquets, which contributed to genomic silencing in embryonal initials, cytomixis and the formation of pycnotic micronucleated cells. Dispersal of female and male parthenospores displayed heteromorphic asexual heterospory in an aqueous environment.

  13. Noninvasive imaging systems for gametes and embryo selection in IVF programs: a review.

    Science.gov (United States)

    Omidi, Marjan; Faramarzi, Azita; Agharahimi, Azam; Khalili, Mohammad Ali

    2017-09-01

    Optimizing the efficiency of the in vitro fertilization procedure by improving pregnancy rates and reducing the risks of multiple pregnancies simultaneously are the primary goals of the current assisted reproductive technology program. With the move to single embryo transfers, the need for more cost-effective and noninvasive methods for embryo selection prior to transfer is paramount. These aims require advancement in a more acquire gametes/embryo testing and selection procedures using high-tech devices. Therefore, the aim of the present review is to evaluate the efficacy of noninvasive imaging systems in the current literatures, focusing on the potential clinical application in infertile patients undergoing assisted reproductive technology treatments. In this regards, three advanced imaging systems of motile sperm organelle morphology examination, polarization microscopy and time-lapse monitoring for the best selection of the gametes and preimplantation embryos are introduced in full. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  14. Gamete and Embryo Donation and Surrogacy in Australia: The Social Context and Regulatory Framework

    Science.gov (United States)

    Hammarberg, Karin; Johnson, Louise; Petrillo, Tracey

    2011-01-01

    The social and legal acceptability of third-party reproduction varies around the world. In Australia, gamete and embryo donation and surrogacy are permitted within the regulatory framework set out by federal and state governments. The aim of this paper is to describe the social context and regulatory framework for third-party reproduction in Australia. This is a review of current laws and regulations related to third-party reproduction in Australia. Although subtle between-state differences exist, third-party reproduction is by and large a socially acceptable and legally permissible way to form a family throughout Australia. The overarching principles that govern the practice of third-party reproduction are altruism; the right of donorconceived people to be informed of their biological origins; and the provision of comprehensive counselling about the social, psychological, physical, ethical, financial and legal implications of third-party reproduction to those considering donating or receiving gametes or embryos and entering surrogacy arrangements. These principles ensure that donors are not motivated by financial gain, donor offspring can identify and meet with the person or persons who donated gametes or embryos, and prospective donors and recipients are aware of and have carefully considered the potential consequences of third-party reproduction. Australian state laws and federal guidelines prohibit commercial and anonymous third-party reproduction; mandate counselling of all parties involved in gamete and embryo donation and surrogacy arrangements; and require clinics to keep records with identifying and non- identifying information about the donor/s to allow donor-conceived offspring to trace their biological origins. PMID:24851179

  15. Gamete and Embryo Donation and Surrogacy in Australia:The Social Context and Regulatory Framework

    Directory of Open Access Journals (Sweden)

    Karin Hammarberg

    2011-01-01

    Full Text Available The social and legal acceptability of third-party reproduction varies around the world. In Australia,gamete and embryo donation and surrogacy are permitted within the regulatory framework setout by federal and state governments. The aim of this paper is to describe the social context andregulatory framework for third-party reproduction in Australia.This is a review of current laws and regulations related to third-party reproduction in Australia.Although subtle between-state differences exist, third-party reproduction is by and large a sociallyacceptable and legally permissible way to form a family throughout Australia. The overarchingprinciples that govern the practice of third-party reproduction are altruism; the right of donorconceivedpeople to be informed of their biological origins; and the provision of comprehensivecounselling about the social, psychological, physical, ethical, financial and legal implications ofthird-party reproduction to those considering donating or receiving gametes or embryos and enteringsurrogacy arrangements. These principles ensure that donors are not motivated by financial gain,donor offspring can identify and meet with the person or persons who donated gametes or embryos,and prospective donors and recipients are aware of and have carefully considered the potentialconsequences of third-party reproduction.Australian state laws and federal guidelines prohibit commercial and anonymous third-partyreproduction; mandate counselling of all parties involved in gamete and embryo donationand surrogacy arrangements; and require clinics to keep records with identifying and nonidentifyinginformation about the donor/s to allow donor-conceived offspring to trace theirbiological origins.

  16. Two-generation analysis of pollen flow across a landscape. I. Male gamete heterogeneity among females.

    Science.gov (United States)

    Smouse, P E; Dyer, R J; Westfall, R D; Sork, V L

    2001-02-01

    Gene flow is a key factor in the spatial genetic structure in spatially distributed species. Evolutionary biologists interested in microevolutionary processess and conservation biologists interested in the impact of landscape change require a method that measures the real time process of gene movement. We present a novel two-generation (parent-offspring) approach to the study of genetic structure (TwoGener) that allows us to quantify heterogeneity among the male gamete pools sampled by maternal trees scattered across the landscape and to estimate mean pollination distance and effective neighborhood size. First, we describe the model's elements: genetic distance matrices to estimate intergametic distances, molecular analysis of variance to determine whether pollen profiles differ among mothers, and optimal sampling considerations. Second, we evaluate the model's effectiveness by simulating spatially distributed populations. Spatial heterogeneity in male gametes can be estimated by phiFT, a male gametic analogue of Wright's F(ST) and an inverse function of mean pollination distance. We illustrate TwoGener in cases where the male gamete can be categorically or ambiguously determined. This approach does not require the high level of genetic resolution needed by parentage analysis, but the ambiguous case is vulnerable to bias in the absence of adequate genetic resolution. Finally, we apply TwoGener to an empirical study of Quercus alba in Missouri Ozark forests. We find that phiFT = 0.06, translating into about eight effective pollen donors per female and an effective pollination neighborhood as a circle of radius about 17 m. Effective pollen movement in Q. alba is more restricted than previously realized, even though pollen is capable of moving large distances. This case study illustrates that, with a modest investment in field survey and laboratory analysis, the TwoGener approach permits inferences about landscape-level gene movements.

  17. Three members of the 6-cys protein family of Plasmodium play a role in gamete fertility.

    Directory of Open Access Journals (Sweden)

    Melissa R van Dijk

    2010-04-01

    Full Text Available The process of fertilization is critically dependent on the mutual recognition of gametes and in Plasmodium, the male gamete surface protein P48/45 is vital to this process. This protein belongs to a family of 10 structurally related proteins, the so called 6-cys family. To identify the role of additional members of this family in Plasmodium fertilisation, we performed genetic and functional analysis on the five members of the 6-cys family that are transcribed during the gametocyte stage of P. berghei. This analysis revealed that in addition to P48/45, two members (P230 and P47 also play an essential role in the process of parasite fertilization. Mating studies between parasites lacking P230, P48/45 or P47 demonstrate that P230, like P48/45, is a male fertility factor, consistent with the previous demonstration of a protein complex containing both P48/45 and P230. In contrast, disruption of P47 results in a strong reduction of female fertility, while males remain unaffected. Further analysis revealed that gametes of mutants lacking expression of p48/45 or p230 or p47 are unable to either recognise or attach to each other. Disruption of the paralog of p230, p230p, also specifically expressed in gametocytes, had no observable effect on fertilization. These results indicate that the P. berghei 6-cys family contains a number of proteins that are either male or female specific ligands that play an important role in gamete recognition and/or attachment. The implications of low levels of fertilisation that exist even in the absence of these proteins, indicating alternative pathways of fertilisation, as well as positive selection acting on these proteins, are discussed in the context of targeting these proteins as transmission blocking vaccine candidates.

  18. Gamete and embryo donation and surrogacy in australia: the social context and regulatory framework.

    Science.gov (United States)

    Hammarberg, Karin; Johnson, Louise; Petrillo, Tracey

    2011-01-01

    The social and legal acceptability of third-party reproduction varies around the world. In Australia, gamete and embryo donation and surrogacy are permitted within the regulatory framework set out by federal and state governments. The aim of this paper is to describe the social context and regulatory framework for third-party reproduction in Australia. This is a review of current laws and regulations related to third-party reproduction in Australia. Although subtle between-state differences exist, third-party reproduction is by and large a socially acceptable and legally permissible way to form a family throughout Australia. The overarching principles that govern the practice of third-party reproduction are altruism; the right of donorconceived people to be informed of their biological origins; and the provision of comprehensive counselling about the social, psychological, physical, ethical, financial and legal implications of third-party reproduction to those considering donating or receiving gametes or embryos and entering surrogacy arrangements. These principles ensure that donors are not motivated by financial gain, donor offspring can identify and meet with the person or persons who donated gametes or embryos, and prospective donors and recipients are aware of and have carefully considered the potential consequences of third-party reproduction. Australian state laws and federal guidelines prohibit commercial and anonymous third-party reproduction; mandate counselling of all parties involved in gamete and embryo donation and surrogacy arrangements; and require clinics to keep records with identifying and non- identifying information about the donor/s to allow donor-conceived offspring to trace their biological origins.

  19. Making muslim babies: Ivf and gamete donation in sunni versus shi’a islam

    Science.gov (United States)

    2006-01-01

    Medical anthropological research on science, biotechnology, and religion has focused on the “local moral worlds” of men and women as they make difficult decisions regarding their health and the beginnings and endings of human life. This paper focuses on the local moral worlds of infertile Muslims as they attempt to make, in the religiously correct fashion, Muslim babies at in vitro fertilization (IVF) clinics in Egypt and Lebanon. As early as 1980, authoritative fatwas issued from Egypt’s famed Al-Azhar University suggested that IVF and similar technologies are permissible as long as they do not involve any form of third-party donation (of sperm, eggs, embryos, or uteruses). Since the late 1990s, however, divergences in opinion over third-party gamete donation have occurred between Sunni and Shi’ite Muslims, with Iran’s leading ayatollah permitting gamete donation under certain conditions. This Iranian fatwa has had profound implications for the country of Lebanon, where a Shi’ite majority also seeks IVF services. Based on three periods of ethnographic research in Egyptian and Lebanese IVF clinics, this paper explores official and unofficial religious discourses surrounding the practice of IVF and third-party donation in the Muslim world, as well as the gender implications of gamete donation for Muslim marriages. PMID:17051430

  20. Peering beneath the surface: novel imaging techniques to noninvasively select gametes and embryos for ART.

    Science.gov (United States)

    Jasensky, Joshua; Swain, Jason E

    2013-10-01

    Embryo imaging has long been a critical tool for in vitro fertilization laboratories, aiding in morphological assessment of embryos, which remains the primary tool for embryo selection. With the recent emergence of clinically applicable real-time imaging systems to assess embryo morphokinetics, a renewed interest has emerged regarding noninvasive methods to assess gamete and embryo development as a means of inferring quality. Several studies exist that utilize novel imaging techniques to visualize or quantify intracellular components of gametes and embryos with the intent of correlating localization of organelles or molecular constitution with quality or outcome. However, the safety of these approaches varies due to the potential detrimental impact of light exposure or other variables. Along with complexity of equipment and cost, these drawbacks currently limit clinical application of these novel microscopes and imaging techniques. However, as evidenced by clinical incorporation of some real-time imaging devices as well as use of polarized microscopy, some of these imaging approaches may prove to be useful. This review summarizes the existing literature on novel imaging approaches utilized to examine gametes and embryos. Refinement of some of these imaging systems may permit clinical application and serve as a means to offer new, noninvasive selection tools to improve outcomes for various assisted reproductive technology procedures.

  1. The functional domain of GCS1-based gamete fusion resides in the amino terminus in plant and parasite species.

    Directory of Open Access Journals (Sweden)

    Toshiyuki Mori

    Full Text Available Fertilization is one of the most important processes in all organisms utilizing sexual reproduction. In a previous study, we succeeded in identifying a novel male gametic transmembrane protein GCS1 (GENERATIVE CELL SPECIFIC 1, also called HAP2 (HAPLESS 2 in the male-sterile Arabidopsis thaliana mutants, as a factor critical to gamete fusion in flowering plants. Interestingly, GCS1 is highly conserved among various eukaryotes covering plants, protists and invertebrates. Of these organisms, Chlamydomonas (green alga and Plasmodium (malaria parasite GCS1s similarly show male gametic expression and gamete fusion function. Since it is generally believed that protein factors controlling gamete fusion have rapidly evolved and different organisms utilize species-specific gamete fusion factors, GCS1 may be an ancient fertilization factor derived from the common ancestor of those organisms above. And therefore, its molecular structure and function are important to understanding the common molecular mechanics of eukaryotic fertilization. In this study, we tried to detect the central functional domain(s of GCS1, using complementation assay of Arabidopsis GCS1 mutant lines expressing modified GCS1. As a result, the positively-charged C-terminal sequence of this protein is dispensable for gamete fusion, while the highly conserved N-terminal domain is critical to GCS1 function. In addition, in vitro fertilization assay of Plasmodium berghei (mouse malaria parasite knock-in lines expressing partly truncated GCS1 showed similar results. Those findings above indicate that the extracellular N-terminus alone is sufficient for GCS1-based gamete fusion.

  2. Egg CD9 protein tides correlated with sperm oscillations tune the gamete fusion ability in mammal.

    Science.gov (United States)

    Ravaux, Benjamin; Favier, Sophie; Perez, Eric; Gourier, Christine

    2018-01-23

    Mammalian fertilization involves membrane events -adhesion, fusion, sperm engulfment, membrane block to polyspermy- whose causes remain largely unknown. Recently, specific oscillations of the sperm in contact with the egg were shown to be necessary for fusion. Using a microfluidic chip to impose the venue for the encounter of two gametes allowed real-time observation of the membrane remodelling occurring at the sperm/egg interface. The spatiotemporal mapping of egg CD9 revealed that this protein concentrates at the egg/sperm interface as a result of sperm oscillations, until a CD9-rich platform is nucleated on which fusion immediately takes place. Within 2 to 5 minutes after fusion, most of the CD9 leaves the egg for the external aqueous medium. Then an egg membrane wave engulfs the sperm head in approximately 25 minutes. These results show that sperm oscillations initiate the CD9 recruitment that causes gamete fusion after which CD9 and associated proteins leave the membrane in a process likely to contribute to block polyspermy. They highlight that the gamete fusion story in mammals is an unexpected interplay between mechanical constraints and proteins. © The Author(s) (2018). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS. All rights reserved.

  3. Globalization and gametes: reproductive 'tourism,' Islamic bioethics, and Middle Eastern modernity.

    Science.gov (United States)

    Inhorn, Marcia C

    2011-04-01

    'Reproductive tourism' has been defined as the search for assisted reproductive technologies (ARTs) and human gametes (eggs, sperm, embryos) across national and international borders. This article conceptualizes reproductive tourism within 'global reproscapes,' which involve the circulation of actors, technologies, money, media, ideas, and human gametes, all moving in complicated manners across geographical landscapes. Focusing on the Muslim countries of the Middle East, the article explores the Islamic 'local moral worlds' informing the movements of Middle Eastern infertile couples. The ban on third-party gamete donation in Sunni Muslim-majority countries and the recent allowance of donor technologies in the Shia Muslim-majority countries of Iran and Lebanon have led to significant movements of infertile couples across Middle Eastern national borders. In the new millennium, Iran is leading the way into this 'brave new world' of high-tech, third-party assisted conception, with Islamic bioethical discourses being used to justify various forms of technological assistance. Although the Middle East is rarely regarded in this way, it is a key site for understanding the intersection of technoscience, religious morality, and modernity, all of which are deeply implicated in the new world of reproductive tourism.

  4. Efficient computation of the inverse of gametic relationship matrix for a marked QTL

    Directory of Open Access Journals (Sweden)

    Iwaisaki Hiroaki

    2006-04-01

    Full Text Available Abstract Best linear unbiased prediction of genetic merits for a marked quantitative trait locus (QTL using mixed model methodology includes the inverse of conditional gametic relationship matrix (G-1 for a marked QTL. When accounting for inbreeding, the conditional gametic relationships between two parents of individuals for a marked QTL are necessary to build G-1 directly. Up to now, the tabular method and its adaptations have been used to compute these relationships. In the present paper, an indirect method was implemented at the gametic level to compute these few relationships. Simulation results showed that the indirect method can perform faster with significantly less storage requirements than adaptation of the tabular method. The efficiency of the indirect method was mainly due to the use of the sparseness of G-1. The indirect method can also be applied to construct an approximate G-1 for populations with incomplete marker data, providing approximate probabilities of descent for QTL alleles for individuals with incomplete marker data.

  5. Safe sex

    Science.gov (United States)

    ... sex; Sexually transmitted - safe sex; GC - safe sex; Gonorrhea - safe sex; Herpes - safe sex; HIV - safe sex; ... contact. STIs include: Chlamydia Genital herpes Genital warts Gonorrhea Hepatitis HIV HPV Syphilis STIs are also called ...

  6. The long path to pregnancy: early experience with dual anonymous gamete donation in a European in vitro fertilisation referral centre

    Directory of Open Access Journals (Sweden)

    Sills Eric

    2010-08-01

    Full Text Available Abstract Background This investigation describes features of patients undergoing in vitro fertilisation (IVF and embryo transfer (ET where both gametes were obtained from anonymous donors. Methods Gamete unsuitability or loss was confirmed in both members of seven otherwise healthy couples presenting for reproductive endocrinology consultation over a 12-month interval in Ireland. IVF was undertaken with fresh oocytes provided by anonymous donors in Ukraine; frozen sperm (anonymous donor was obtained from a licensed tissue establishment. For recipients, saline-enhanced sonography was used to assess intrauterine contour with endometrial preparation via transdermal estrogen. Results Among commissioning couples, mean±SD female and male age was 41.9 ± 3.7 and 44.6 ± 3.5 yrs, respectively. During this period, female age for non dual anonymous gamete donation IVF patients was 37.9 ± 3 yrs (p Conclusions Mean age of females undergoing dual anonymous donor gamete donation with IVF is significantly higher than the background IVF patient population. Even when neither partner is able to contribute any gametes for IVF, the clinical pregnancy rate per transfer can be satisfactory if both anonymous egg and sperm donation are used concurrently. Our report emphasises the role of pre-treatment counselling in dual anonymous gamete donation, and presents a coordinated screening and treatment approach in IVF where this option may be contemplated.

  7. Novel sex cells and evidence for sex pheromones in diatoms.

    Science.gov (United States)

    Sato, Shinya; Beakes, Gordon; Idei, Masahiko; Nagumo, Tamotsu; Mann, David G

    2011-01-01

    Diatoms belong to the stramenopiles, one of the largest groups of eukaryotes, which are primarily characterized by a presence of an anterior flagellum with tubular mastigonemes and usually a second, smooth flagellum. Based on cell wall morphology, diatoms have historically been divided into centrics and pennates, of which only the former have flagella and only on the sperm. Molecular phylogenies show the pennates to have evolved from among the centrics. However, the timing of flagellum loss--whether before the evolution of the pennate lineage or after--is unknown, because sexual reproduction has been so little studied in the 'araphid' basal pennate lineages, to which Pseudostaurosira belongs. Sexual reproduction of an araphid pennate, Pseudostaurosira trainorii, was studied with light microscopy (including time lapse observations and immunofluorescence staining observed under confocal scanning laser microscopy) and SEM. We show that the species produces motile male gametes. Motility is mostly associated with the extrusion and retrieval of microtubule-based 'threads', which are structures hitherto unknown in stramenopiles, their number varying from one to three per cell. We also report experimental evidence for sex pheromones that reciprocally stimulate sexualization of compatible clones and orientate motility of the male gametes after an initial 'random walk'. The threads superficially resemble flagella, in that both are produced by male gametes and contain microtubules. However, one striking difference is that threads cannot beat or undulate and have no motility of their own, and they do not bear mastigonemes. Threads are sticky and catch and draw objects, including eggs. The motility conferred by the threads is probably crucial for sexual reproduction of P. trainorii, because this diatom is non-motile in its vegetative stage but obligately outbreeding. Our pheromone experiments are the first studies in which gametogenesis has been induced in diatoms by cell

  8. Novel sex cells and evidence for sex pheromones in diatoms.

    Directory of Open Access Journals (Sweden)

    Shinya Sato

    Full Text Available BACKGROUND: Diatoms belong to the stramenopiles, one of the largest groups of eukaryotes, which are primarily characterized by a presence of an anterior flagellum with tubular mastigonemes and usually a second, smooth flagellum. Based on cell wall morphology, diatoms have historically been divided into centrics and pennates, of which only the former have flagella and only on the sperm. Molecular phylogenies show the pennates to have evolved from among the centrics. However, the timing of flagellum loss--whether before the evolution of the pennate lineage or after--is unknown, because sexual reproduction has been so little studied in the 'araphid' basal pennate lineages, to which Pseudostaurosira belongs. METHODS/PRINCIPAL FINDING: Sexual reproduction of an araphid pennate, Pseudostaurosira trainorii, was studied with light microscopy (including time lapse observations and immunofluorescence staining observed under confocal scanning laser microscopy and SEM. We show that the species produces motile male gametes. Motility is mostly associated with the extrusion and retrieval of microtubule-based 'threads', which are structures hitherto unknown in stramenopiles, their number varying from one to three per cell. We also report experimental evidence for sex pheromones that reciprocally stimulate sexualization of compatible clones and orientate motility of the male gametes after an initial 'random walk'. CONCLUSIONS/SIGNIFICANCE: The threads superficially resemble flagella, in that both are produced by male gametes and contain microtubules. However, one striking difference is that threads cannot beat or undulate and have no motility of their own, and they do not bear mastigonemes. Threads are sticky and catch and draw objects, including eggs. The motility conferred by the threads is probably crucial for sexual reproduction of P. trainorii, because this diatom is non-motile in its vegetative stage but obligately outbreeding. Our pheromone experiments

  9. Sex before the State: Civic Sex, Reproductive Innovations, and Gendered Parental Identity.

    Science.gov (United States)

    Murphy, Timothy F

    2017-04-01

    Certain changes in the way that states classify people by sex as well as certain reproductive innovations undercut the rationale for state identification of people as male or female in signifying gendered parental relationships to children. At present, people known to the state as men may be genetic mothers to their children; people known to the state as women may be genetic fathers to their children. Synthetic gametes would make it possible for transgender men to be genetically related to children as fathers and transgender women to be genetically related to children as mothers, even if they have otherwise relied on naturally-occurring gametes to be genetic mothers and genetic fathers of children respectively. Synthetic gametes would presumably make it possible for any person to be the genetic father or genetic mother of children, even in a mix-and-match way. Other reproductive innovations will also undercut existing expectations of gendered parental identity. Uterus transplants would uncouple the maternal function of gestation from women, allowing men to share in maternity that way. Extracorporeal gestation ((ExCG)-gestation outside anyone's body-would also undercut the until-now absolute connection between female sex and maternity. In kind, effects such as these-undoing conventionally gendered parenthood-undercut the state's interest in knowing whether parents are male or female in relation to a given child, as against knowing simply whether someone stands in a parental relationship to that child, as a matter of rights and duties.

  10. The long path to pregnancy: early experience with dual anonymous gamete donation in a European in vitro fertilisation referral centre

    LENUS (Irish Health Repository)

    Sills, Eric Scott

    2010-08-11

    Abstract Background This investigation describes features of patients undergoing in vitro fertilisation (IVF) and embryo transfer (ET) where both gametes were obtained from anonymous donors. Methods Gamete unsuitability or loss was confirmed in both members of seven otherwise healthy couples presenting for reproductive endocrinology consultation over a 12-month interval in Ireland. IVF was undertaken with fresh oocytes provided by anonymous donors in Ukraine; frozen sperm (anonymous donor) was obtained from a licensed tissue establishment. For recipients, saline-enhanced sonography was used to assess intrauterine contour with endometrial preparation via transdermal estrogen. Results Among commissioning couples, mean±SD female and male age was 41.9 ± 3.7 and 44.6 ± 3.5 yrs, respectively. During this period, female age for non dual anonymous gamete donation IVF patients was 37.9 ± 3 yrs (p < 0.001). Infertility duration was ≥3 yrs for couples enrolling in dual gamete donation, and each had ≥2 prior failed fertility treatments using native oocytes. All seven recipient couples proceeded to embryo transfer, although one patient had two transfers. Clinical pregnancy was achieved for 5\\/7 (71.4%) patients. Non-transferred cryopreserved embryos were available for all seven couples. Conclusions Mean age of females undergoing dual anonymous donor gamete donation with IVF is significantly higher than the background IVF patient population. Even when neither partner is able to contribute any gametes for IVF, the clinical pregnancy rate per transfer can be satisfactory if both anonymous egg and sperm donation are used concurrently. Our report emphasises the role of pre-treatment counselling in dual anonymous gamete donation, and presents a coordinated screening and treatment approach in IVF where this option may be contemplated.

  11. Pathogenesis of germ cell neoplasia in testicular dysgenesis and disorders of sex development

    DEFF Research Database (Denmark)

    Jørgensen, Anne; Lindhardt Johansen, Marie; Juul, Anders

    2015-01-01

    in individuals with 46,XY DSD. We summarise knowledge concerning development and sex differentiation of human gonads, with focus on sex-dimorphic steps of germ cell maturation, including meiosis. We also briefly outline the histopathology of germ cell neoplasia in situ (GCNIS) and gonadoblastoma (GDB), which......Development of human gonads is a sex-dimorphic process which evolved to produce sex-specific types of germ cells. The process of gonadal sex differentiation is directed by the action of the somatic cells and ultimately results in germ cells differentiating to become functional gametes through...

  12. Cardiac arrest during gamete release in chum salmon regulated by the parasympathetic nerve system.

    Directory of Open Access Journals (Sweden)

    Yuya Makiguchi

    Full Text Available Cardiac arrest caused by startling stimuli, such as visual and vibration stimuli, has been reported in some animals and could be considered as an extraordinary case of bradycardia and defined as reversible missed heart beats. Variability of the heart rate is established as a balance between an autonomic system, namely cholinergic vagus inhibition, and excitatory adrenergic stimulation of neural and hormonal action in teleost. However, the cardiac arrest and its regulating nervous mechanism remain poorly understood. We show, by using electrocardiogram (ECG data loggers, that cardiac arrest occurs in chum salmon (Oncorhynchus keta at the moment of gamete release for 7.39+/-1.61 s in females and for 5.20+/-0.97 s in males. The increase in heart rate during spawning behavior relative to the background rate during the resting period suggests that cardiac arrest is a characteristic physiological phenomenon of the extraordinarily high heart rate during spawning behavior. The ECG morphological analysis showed a peaked and tall T-wave adjacent to the cardiac arrest, indicating an increase in potassium permeability in cardiac muscle cells, which would function to retard the cardiac action potential. Pharmacological studies showed that the cardiac arrest was abolished by injection of atropine, a muscarinic receptor antagonist, revealing that the cardiac arrest is a reflex response of the parasympathetic nerve system, although injection of sotalol, a beta-adrenergic antagonist, did not affect the cardiac arrest. We conclude that cardiac arrest during gamete release in spawning release in spawning chum salmon is a physiological reflex response controlled by the parasympathetic nervous system. This cardiac arrest represents a response to the gaping behavior that occurs at the moment of gamete release.

  13. Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures

    Directory of Open Access Journals (Sweden)

    Cowling Wallace A

    2011-06-01

    Full Text Available Abstract Background Unreduced gametes (gametes with the somatic chromosome number may provide a pathway for evolutionary speciation via allopolyploid formation. We evaluated the effect of genotype and temperature on male unreduced gamete formation in Brassica allotetraploids and their interspecific hybrids. The frequency of unreduced gametes post-meiosis was estimated in sporads from the frequency of dyads or giant tetrads, and in pollen from the frequency of viable giant pollen compared with viable normal pollen. Giant tetrads were twice the volume of normal tetrads, and presumably resulted from pre-meiotic doubling of chromosome number. Giant pollen was defined as pollen with more than 1.5 × normal diameter, under the assumption that the doubling of DNA content in unreduced gametes would approximately double the pollen cell volume. The effect of genotype was assessed in five B. napus, two B. carinata and one B. juncea parents and in 13 interspecific hybrid combinations. The effect of temperature was assessed in a subset of genotypes in hot (day/night 30°C/20°C, warm (25°C/15°C, cool (18°C/13°C and cold (10°C/5°C treatments. Results Based on estimates at the sporad stage, some interspecific hybrid genotypes produced unreduced gametes (range 0.06 to 3.29% at more than an order of magnitude higher frequency than in the parents (range 0.00% to 0.11%. In nine hybrids that produced viable mature pollen, the frequency of viable giant pollen (range 0.2% to 33.5% was much greater than in the parents (range 0.0% to 0.4%. Giant pollen, most likely formed from unreduced gametes, was more viable than normal pollen in hybrids. Two B. napus × B. carinata hybrids produced 9% and 23% unreduced gametes based on post-meiotic sporad observations in the cold temperature treatment, which was more than two orders of magnitude higher than in the parents. Conclusions These results demonstrate that sources of unreduced gametes, required for the triploid

  14. Dynamics of gamete production and mating in the parasitic protist Trypanosoma brucei.

    Science.gov (United States)

    Peacock, Lori; Bailey, Mick; Gibson, Wendy

    2016-07-20

    Sexual reproduction in Plasmodium falciparum and Trypanosoma brucei occurs in the insect vector and is important in generating hybrid strains with different combinations of parental characteristics. Production of hybrid parasite genotypes depends on the likelihood of co-infection of the vector with multiple strains. In mosquitoes, existing infection with Plasmodium facilitates the establishment of a second infection, although the asynchronicity of gamete production subsequently prevents mating. In the trypanosome/tsetse system, flies become increasingly refractory to infection as they age, so the likelihood of a fly acquiring a second infection also decreases. This effectively restricts opportunities for trypanosome mating to co-infections picked up by the fly on its first feed, unless an existing infection increases the chance of successful second infection as in the Plasmodium/mosquito system. Using green and red fluorescent trypanosomes, we compared the rates of trypanosome infection and hybrid production in flies co-infected on the first feed, co-infected on a subsequent feed 18 days after emergence, or fed sequentially with each trypanosome clone 18 days apart. Infection rates were highest in the midguts and salivary glands (SG) of flies that received both trypanosome clones in their first feed, and were halved when the infected feed was delayed to day 18. In flies fed the two trypanosome clones sequentially, the second clone often failed to establish a midgut infection and consequently was not present in the SG. Nevertheless, hybrids were recovered from all three groups of infected flies. Meiotic stages and gametes were produced continuously from day 11 to 42 after the infective feed, and in sequentially infected flies, the co-occurrence of gametes led to hybrid formation. We found that a second trypanosome strain can establish infection in the tsetse SG 18 days after the first infected feed, with co-mingling of gametes and production of trypanosome hybrids

  15. ESHRE Task Force on Ethics and Law 21: genetic screening of gamete donors: ethical issues.

    Science.gov (United States)

    Dondorp, W; De Wert, G; Pennings, G; Shenfield, F; Devroey, P; Tarlatzis, B; Barri, P; Diedrich, K; Eichenlaub-Ritter, U; Tüttelmann, F; Provoost, V

    2014-07-01

    This Task Force document explores the ethical issues involved in the debate about the scope of genetic screening of gamete donors. Calls for expanded donor screening arise against the background of both occasional findings of serious but rare genetic conditions in donors or donor offspring that were not detected through present screening procedures and the advent of new genomic technologies promising affordable testing of donors for a wide range of conditions. Ethical principles require that all stakeholders' interests are taken into account, including those of candidate donors. The message of the profession should be that avoiding all risks is impossible and that testing should remain proportional.

  16. The evolution of sexes: A specific test of the disruptive selection theory.

    Science.gov (United States)

    da Silva, Jack

    2018-01-01

    The disruptive selection theory of the evolution of anisogamy posits that the evolution of a larger body or greater organismal complexity selects for a larger zygote, which in turn selects for larger gametes. This may provide the opportunity for one mating type to produce more numerous, small gametes, forcing the other mating type to produce fewer, large gametes. Predictions common to this and related theories have been partially upheld. Here, a prediction specific to the disruptive selection theory is derived from a previously published game-theoretic model that represents the most complete description of the theory. The prediction, that the ratio of macrogamete to microgamete size should be above three for anisogamous species, is supported for the volvocine algae. A fully population genetic implementation of the model, involving mutation, genetic drift, and selection, is used to verify the game-theoretic approach and accurately simulates the evolution of gamete sizes in anisogamous species. This model was extended to include a locus for gamete motility and shows that oogamy should evolve whenever there is costly motility. The classic twofold cost of sex may be derived from the fitness functions of these models, showing that this cost is ultimately due to genetic conflict.

  17. Human DAZL, DAZ and BOULE genes modulate primordial germ cell and haploid gamete formation

    Science.gov (United States)

    Kee, Kehkooi; Angeles, Vanessa T; Flores, Martha; Nguyen, Ha Nam; Pera, Renee A Reijo

    2009-01-01

    The leading cause of infertility in men and women is quantitative and qualitative defects in human germ cell (oocyte and sperm) development. Yet, it has not been possible to examine the unique developmental genetics of human germ cell formation and differentiation due to inaccessibility of germ cells during fetal development. Although several studies have shown that germ cells can be differentiated from mouse and human embryonic stem cells, human germ cells differentiated in these studies generally did not develop beyond the earliest stages1-8. Here we used a germ cell reporter to quantitate and isolate primordial germ cells derived from both male and female hESCs. Then, by silencing and overexpressing genes that encode germ cell-specific cytoplasmic RNA-binding proteins (not transcription factors), we modulated human germ cell formation and developmental progression. We observed that human DAZL (Deleted in AZoospermia-Like) functions in primordial germ cell formation, whereas closely-related genes, DAZ and BOULE, promote later stages of meiosis and development of haploid gametes. These results are significant to the generation of gametes for future basic science and potential clinical applications. PMID:19865085

  18. Effect of gamma radiation on mutability in male gametes of Japanese quail (Coturnix coturnix japonica)

    Energy Technology Data Exchange (ETDEWEB)

    Baumgartner, J [Vyskumny Ustav Chovu a Slachtenia Hydiny, Laboratorim Genetiky, Ivanka pri Dunaji (Czechoslovakia)

    1978-01-01

    An analysis of the mutability of developmental stages of male gametes of the japanese quail (Coturnix coturnix japonica), after irradiation with /sup 60/Co exposures (5.16; 15.48; and 30.96)x10/sup -2/C kg/sup -1/, i.e. 200, 600 and 1200 R, at an exposure rate of 8.59x10/sup -5/C kg/sup -1/s/sup -1/, i.e. O.33 R s/sup -1/, has shown that the rate of overall induced dominant lethality as well as the rate of mutation were highest in spermatocytes of the second order at all exposures. Starting from an exposure of 200 R the following values were found for lethal interference per 1 gamete for 1 R: spermatozoa 2.0x10/sup -3/, spermatides 1.95x10/sup -3/, spermatocytes II 6.1x10/sup -3/, spermatocytes I 4.06x10/sup -3/, spermatogonia in the process of differentiation 6.8x10/sup -3/. When analysing overall embryonic lethality, according to early and late lethality, dominant lethal mutations mainly manifested themsel--ves in the oviductal and germinal developmental periods, so that these periods can be considered as sensitive indices of genetic changes. The spermatogenic epithelium of the japanese quail was found to be greatly radioresistant since not even an exposure to 1200 R caused complete and permanent sterility.

  19. Herbicide impact on Hormosira banksii gametes measured by fluorescence and germination bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Seery, Cliff R. [Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, Westbourne Street, Gore Hill, 2065 NSW (Australia); Gunthorpe, Leanne [Primary Industries Research Victoria (PIRVic), VIC (Australia); Ralph, Peter J. [Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, Westbourne Street, Gore Hill, 2065 NSW (Australia)]. E-mail: peter.ralph@uts.edu.au

    2006-03-15

    The innovative bioassay described here involves chlorophyll a fluorescence measurements of gametes from the macroalgae, Hormosira banksii, where gametes (eggs) were exposed to Diuron, Irgarol and Bromacil. Response was assessed as percent inhibition from control of effective quantum yield ({delta}F/Fm') of photosystem II, herein referred to as % PSII Inhibition. This was measured with the dual-channelled pulse amplitude modulated (PAM) fluorometer, ToxY-PAM. The fluorescence bioassay was run simultaneously with an established H. banksii germination bioassay to compare sensitivity, precision, and time-to-result. The fluorescence bioassay gave highly sensitive results evidenced by EC{sub 5}s (% PSII Inhibition) for Diuron, Irgarol and Bromacil being three, four and three orders of magnitude (respectively) lower than EC{sub 5}s generated from the germination bioassays. Precision of the fluorescence bioassay was demonstrated with low coefficient of variations (<30%) for all three toxicants. With regard to time, the fluorescence bioassay gave results within 6 h, as opposed to more than 50 h for the germination bioassay. - Chlorophyll a fluorescence measurements form the basis of a macroalgal bioassay with many advantages over germination-based methods.

  20. Herbicide impact on Hormosira banksii gametes measured by fluorescence and germination bioassays

    International Nuclear Information System (INIS)

    Seery, Cliff R.; Gunthorpe, Leanne; Ralph, Peter J.

    2006-01-01

    The innovative bioassay described here involves chlorophyll a fluorescence measurements of gametes from the macroalgae, Hormosira banksii, where gametes (eggs) were exposed to Diuron, Irgarol and Bromacil. Response was assessed as percent inhibition from control of effective quantum yield (ΔF/Fm') of photosystem II, herein referred to as % PSII Inhibition. This was measured with the dual-channelled pulse amplitude modulated (PAM) fluorometer, ToxY-PAM. The fluorescence bioassay was run simultaneously with an established H. banksii germination bioassay to compare sensitivity, precision, and time-to-result. The fluorescence bioassay gave highly sensitive results evidenced by EC 5 s (% PSII Inhibition) for Diuron, Irgarol and Bromacil being three, four and three orders of magnitude (respectively) lower than EC 5 s generated from the germination bioassays. Precision of the fluorescence bioassay was demonstrated with low coefficient of variations (<30%) for all three toxicants. With regard to time, the fluorescence bioassay gave results within 6 h, as opposed to more than 50 h for the germination bioassay. - Chlorophyll a fluorescence measurements form the basis of a macroalgal bioassay with many advantages over germination-based methods

  1. Polyploidization mechanisms: temperature environment can induce diploid gamete formation in Rosa sp.

    Science.gov (United States)

    Pécrix, Yann; Rallo, Géraldine; Folzer, Hélène; Cigna, Mireille; Gudin, Serge; Le Bris, Manuel

    2011-06-01

    Polyploidy is an important evolutionary phenomenon but the mechanisms by which polyploidy arises still remain underexplored. There may be an environmental component to polyploidization. This study aimed to clarify how temperature may promote diploid gamete formation considered an essential element for sexual polyploidization. First of all, a detailed cytological analysis of microsporogenesis and microgametogenesis was performed to target precisely the key developmental stages which are the most sensitive to temperature. Then, heat-induced modifications in sporad and pollen characteristics were analysed through an exposition of high temperature gradient. Rosa plants are sensitive to high temperatures with a developmental sensitivity window limited to meiosis. Moreover, the range of efficient temperatures is actually narrow. 36 °C at early meiosis led to a decrease in pollen viability, pollen ectexine defects but especially the appearance of numerous diploid pollen grains. They resulted from dyads or triads mainly formed following heat-induced spindle misorientations in telophase II. A high temperature environment has the potential to increase gamete ploidy level. The high frequencies of diplogametes obtained at some extreme temperatures support the hypothesis that polyploidization events could have occurred in adverse conditions and suggest polyploidization facilitating in a global change context.

  2. Structural relationships among central cell and egg apparatus cells of barley as related to transmission of male gametes

    Directory of Open Access Journals (Sweden)

    David D. Cass

    2014-01-01

    Full Text Available Barley embryo sacs were examined using light and electron microscopy before and during fertilization. One synergid degenerates after pollination with loss of nuclear and cytoplasmic organization and cell wall material between synergid and central cell. Some wall between egg and central cell is also lost. After pollen tube discharge into the degenerate synergid, the male gametes leave the synergid entering a pocket of central cell cytoplasm separated from the synergid only by membranes. This could provide for efficient gamete transmission and possible recognition through specific membrane contacts.

  3. Salmonid Gamete Preservation in the Snake River Basin, 2001 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Robyn; Kucera, Paul

    2002-06-01

    Steelhead (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) populations in the Northwest are decreasing. Genetic diversity is being lost at an alarming rate. Along with reduced population and genetic variability, the loss of biodiversity means a diminished environmental adaptability. The Nez Perce Tribe (Tribe) strives to ensure availability of genetic samples of the existing male salmonid population by establishing and maintaining a germplasm repository. The sampling strategy, initiated in 1992, has been to collect and preserve male salmon and steelhead genetic diversity across the geographic landscape by sampling within the major river subbasins in the Snake River basin, assuming a metapopulation structure existed historically. Gamete cryopreservation conserves genetic diversity in a germplasm repository, but is not a recovery action for listed fish species. The Tribe was funded in 2001 by the Bonneville Power Administration (BPA) and the U.S. Fish and Wildlife Service Lower Snake River Compensation Plan (LSRCP) to coordinate gene banking of male gametes from Endangered Species Act (ESA) listed steelhead and spring and summer chinook salmon in the Snake River basin. In 2001, a total of 398 viable chinook salmon semen samples from the Lostine River, Catherine Creek, upper Grande Ronde River, Lookingglass Hatchery (Imnaha River stock), Lake Creek, the South Fork Salmon River weir, Johnson Creek, Big Creek, Capehorn Creek, Marsh Creek, Pahsimeroi Hatchery, and Sawtooth Hatchery (upper Salmon River stock) were cryopreserved. Also, 295 samples of male steelhead gametes from Dworshak Hatchery, Fish Creek, Grande Ronde River, Little Sheep Creek, Pahsimeroi Hatchery and Oxbow Hatchery were also cryopreserved. The Grande Ronde chinook salmon captive broodstock program stores 680 cryopreserved samples at the University of Idaho as a long-term archive, half of the total samples. A total of 3,206 cryopreserved samples from Snake River basin steelhead and

  4. Reproductive and therapeutic cloning, germline therapy, and purchase of gametes and embryos: comments on Canadian legislation governing reproduction technologies

    Science.gov (United States)

    Bernier, L; Gregoire, D

    2004-01-01

    In this article the three main topics covered in the new legislation are commented on: cloning, germline therapy, and purchase of gametes and embryos. Some important issues also covered in the new legislation, such as privacy and access to information, data protection, identity of donors, and inspection, will not be addressed. PMID:15574437

  5. Cryopreservation of Adult Male Spring and Summer Chinook Salmon Gametes in the Snake River Basin, 1997 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Faurot, Dave; Kucera, Paul A.; Armstrong, Robyn D. (Nez Perce Tribe, Lapwai, ID)

    1998-06-01

    Chinook salmon populations in the Northwest are decreasing in number. The Nez Perce Tribe was funded in 1997 by the Bonneville Power Administration to coordinate and initiate gene banking of adult male gametes from Endangered Species Act (ESA) listed spring and summer chinook salmon in the Snake River basin.

  6. Oocyte banking for anticipated gamete exhaustion (AGE) is a preventive intervention, neither social nor nonmedical.

    Science.gov (United States)

    Stoop, Dominic; van der Veen, Fulco; Deneyer, Michel; Nekkebroeck, Julie; Tournaye, Herman

    2014-05-01

    The scope of female fertility preservation through cryopreservation of oocytes or ovarian cortex has widened from mainly oncological indications to a variety of fertility-threatening conditions. So far, no specific universally accepted denomination name has been given to cryopreservation of oocytes or ovarian cortex for the prevention of age-related fertility decline. We argue that the commonly used phrases 'social' and 'nonmedical freezing' to denote the indication for cryopreservation are not entirely correct. We suggest 'AGE banking', as this has not only the advantage of being catchy but also depicts the exact indication for the strategy, anticipated gamete exhaustion. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  7. Collection of gametes from live axolotl, Ambystoma mexicanum, and standardization of in vitro fertilization.

    Science.gov (United States)

    Mansour, N; Lahnsteiner, F; Patzner, R A

    2011-01-15

    This study established the first protocol for collection of gametes from live axolotl, Ambystoma mexicanum, by gentle abdominal massage and in vitro fertilization. To stimulate spermiation and ovulation, human chorionic gonadotrophin (hCG) and Ovopel pellets, which are commercially used to stimulate spawning in fish, were tested. The hCG was more effective than Ovopel pellets and yielded a higher semen volume in the injected males and a shorter response time in the females. Collected semen by this method was already motile and fertile. Fertile eggs could be collected in 3-4 successive collection times after the female has started the typical spawning behaviour. The fertilization condition that yielded the highest hatching rate was mixing semen with eggs before the addition of a fertilization saline solution (20 mmol/l NaCl, 1 mmol/l KCl, 1 mmol/l Mg(2)SO(4), 1 mmol Ca(2)Cl, 3 mmol NaHCO(3), 10 mmol/l Tris, pH 8.5 - Osmolality = 65 mosmol/kg). When the pH of the fertilization solution was increased to ≥ 10, the hatching rate was significantly increased. The use of fertilization solutions with osmolalities of ≥ 150 and ≥ 182 were accompanied with a significant decrease in hatching rates and the appearance of deformed larvae, respectively. In conclusion, a reliable protocol for gamete collection from live axolotl is established as a laboratory model of in vitro fertilization for urodele amphibians. This protocol may be transferable to endangered urodeles. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Comparative study of the germination of Ulva prolifera gametes on various substrates

    Science.gov (United States)

    Geng, Huixia; Yan, Tian; Zhou, Mingjiang; Liu, Qing

    2015-09-01

    Since 2007, massive green tides have occurred every summer in the southern Yellow Sea (YS), China. They have caused severe ecological consequences and huge economic losses. Ulva prolifera originated from Subei Shoal of the YS was confirmed as causative species of the green tides. The Porphyra yezoensis aquaculture rafts in the Subei Shoal have been highly suspected to be the "seed bed" of the green tides, because U. prolifera abundantly fouled the Porphyra yezoensis aquaculture facilities. Besides, various habitats of aquaculture ponds along the Jiangsu coastline and mudflat in the Subei Shoal were proposed to be possible sources of green tides. To understand the "seed" of the green tides in the southern YS and mitigate the original biomass of the green tide, various materials used as substrates for the germination of U. prolifera gametes were tested in this study. Culture experiments showed the following: 1) materials used in the P. yezoensis rafts (plastic, bamboo, jute rope, plastic rope, nylon netting, and plastic netting) displayed a significantly higher germination rate than those associated with mudflats and aquaculture ponds (mud, sand and rock); 2) plastics were the best substrates for the germination of U. prolifera gametes; 3) poor germination was found on old fronds of U. prolifera,, and rubber showed inhibitory effect on germination. The success in germination on P. yezoensis rafts related materials supports the notion that these mariculture structures may be involved in acting as a seed bed for green tide macroalgae. The lack of germination on rubber surfaces may suggest one way to limit the proliferation of early stages of U. prolifera.

  9. Evolution of sexes from an ancestral mating-type specification pathway.

    Directory of Open Access Journals (Sweden)

    Sa Geng

    2014-07-01

    Full Text Available Male and female sexes have evolved repeatedly in eukaryotes but the origins of dimorphic sexes and their relationship to mating types in unicellular species are not understood. Volvocine algae include isogamous species such as Chlamydomonas reinhardtii, with two equal-sized mating types, and oogamous multicellular species such as Volvox carteri with sperm-producing males and egg-producing females. Theoretical work predicts genetic linkage of a gamete cell-size regulatory gene(s to an ancestral mating-type locus as a possible step in the evolution of dimorphic gametes, but this idea has not been tested. Here we show that, contrary to predictions, a single conserved mating locus (MT gene in volvocine algae-MID, which encodes a RWP-RK domain transcription factor-evolved from its ancestral role in C. reinhardtii as a mating-type specifier, to become a determinant of sperm and egg development in V. carteri. Transgenic female V. carteri expressing male MID produced functional sperm packets during sexual development. Transgenic male V. carteri with RNA interference (RNAi-mediated knockdowns of VcMID produced functional eggs, or self-fertile hermaphrodites. Post-transcriptional controls were found to regulate cell-type-limited expression and nuclear localization of VcMid protein that restricted its activity to nuclei of developing male germ cells and sperm. Crosses with sex-reversed strains uncoupled sex determination from sex chromosome identity and revealed gender-specific roles for male and female mating locus genes in sexual development, gamete fitness and reproductive success. Our data show genetic continuity between the mating-type specification and sex determination pathways of volvocine algae, and reveal evidence for gender-specific adaptations in the male and female mating locus haplotypes of Volvox. These findings will enable a deeper understanding of how a master regulator of mating-type determination in an ancestral unicellular species was

  10. MPK-1 ERK Controls Membrane Organization in C. elegans Oogenesis via a Sex-Determination Module

    OpenAIRE

    Arur, Swathi; Ohmachi, Mitsue; Berkseth, Matt; Nayak, Sudhir; Hansen, David; Zarkower, David; Schedl, Tim

    2011-01-01

    Tissues that generate specialized cell-types in a production line must coordinate developmental mechanisms with physiological demand, although how this occurs is largely unknown. In the C. elegans hermaphrodite, the developmental sex-determination cascade specifies gamete sex in the distal germline, while physiological sperm signaling activates MPK-1/ERK in the proximal germline to control plasma membrane biogenesis/organization during oogenesis. We discovered repeated utilization of a self-c...

  11. Sex assignment of lake sturgeon (Acipenser fluvescens) based on plasma sex hormone and vitellogenin levels

    Science.gov (United States)

    Craig, J.M.; Papoulias, D.M.; Thomas, M.V.; Annis, M.L.; Boase, J.

    2009-01-01

    This study focused on identifying the sex of lake sturgeon by measuring the sex hormones estradiol and testosterone, and the phosphoprotein vitellogenin (Vtg) in blood plasma by radioimmunoassay and enzyme-linked immunosorbent assay, respectively, and evaluating these techniques as tools in lake sturgeon population management. Surveys of the St Clair River (SCR) lake sturgeon population have characterized it as rebounding by having steady or increasing recruitment since 1997. However, researchers have not been able to effectively determine the sex for most of the sturgeon they capture because few fish caught during surveys are releasing gametes. A total of 115 fish were sampled from May through June in 2004 and 2005 from the SCR, Michigan, USA. Of these, only four females and eight males were verified (i.e. they were releasing gametes at time of capture), resulting in very few fish with which to validate blood hormone and Vtg biomarkers of sex. Fifty-six percent of the fish were assigned a sex designation based on biomarker criteria. Correspondence between actual gonadal sex and biomarker-directed classification was good for the small subset of fish for which gonadal sex was definitively determined. Moreover, application of the steroid values in a predictive sex assignment model developed for white sturgeon misclassified only the same two fish that were misclassified with the steroid and Vtg biomarkers. The experimental results suggest a sex ratio of 1 : 2.7 (F:M), however more conclusive methods are needed to confirm this ratio because so few fish were available for sex validation. Of the 43 males, 14 were within the legal slot limit, 11 were smaller than 1067 mm total length (TL), and 18 were larger than 1270 mm TL. All 15 females were larger than 1270 mm TL, and thus protected by the slot limit criteria. Considering that lake sturgeon are threatened in Michigan, an advantage to using blood plasma assays was that fish were not harmed, and sample collection was

  12. Sex Therapy

    Science.gov (United States)

    Sex therapy Overview Sex therapy is a type of psychotherapy — a general term for treating mental health problems by talking with a mental health professional. Through sex therapy, you can address concerns about sexual function, ...

  13. Salmonid Gamete Preservation in the Snake River Basin : 2000 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Robyn; Kucera, Paul A. [Nez Perce Tribe. Dept. of Fisheries Resource Management, Lapwai, ID (US)

    2001-06-01

    Steelhead (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) populations in the Northwest are decreasing. Genetic diversity is being lost at an alarming rate. The Nez Perce Tribe (Tribe) strives to ensure availability of genetic samples of the existing male salmonid population by establishing and maintaining a germplasm repository. The sampling strategy, initiated in 1992, has been to collect and preserve male salmon and steelhead genetic diversity across the geographic landscape by sampling within the major river subbasins in the Snake River basin, assuming a metapopulation structure existed historically. Gamete cryopreservation conserves genetic diversity in a germplasm repository, but is not a recovery action for listed fish species. The Tribe was funded in 2000 by the Bonneville Power Administration (BPA) and the U.S. Fish and Wildlife Service Lower Snake River Compensation Plan (LSRCP) to coordinate gene banking of male gametes from Endangered Species Act listed steelhead and spring and summer chinook salmon in the Snake River basin. In 2000, a total of 349 viable chinook salmon semen samples from the Lostine River, Catherine Creek, upper Grande Ronde River, Lookingglass Hatchery (Imnaha River stock), Rapid River Hatchery, Lake Creek, the South Fork Salmon River weir, Johnson Creek, Big Creek, Capehorn Creek, Marsh Creek, Pahsimeroi Hatchery, and Sawtooth Hatchery (upper Salmon River stock) were cryopreserved. Also, 283 samples of male steelhead gametes from Dworshak Hatchery, Fish Creek, Grande Ronde River, Imnaha River, Little Sheep Creek, Pahsimeroi Hatchery and Oxbow Hatchery were also cryopreserved. The Tribe acquired 5 frozen steelhead samples from the Selway River collected in 1994 and 15 from Fish Creek sampled in 1993 from the U.S. Geological Survey, for addition into the germplasm repository. Also, 590 cryopreserved samples from the Grande Ronde chinook salmon captive broodstock program are being stored at the University of Idaho as

  14. Sex and death: the effects of innate immune factors on the sexual reproduction of malaria parasites.

    Directory of Open Access Journals (Sweden)

    Ricardo S Ramiro

    2011-03-01

    Full Text Available Malaria parasites must undergo a round of sexual reproduction in the blood meal of a mosquito vector to be transmitted between hosts. Developing a transmission-blocking intervention to prevent parasites from mating is a major goal of biomedicine, but its effectiveness could be compromised if parasites can compensate by simply adjusting their sex allocation strategies. Recently, the application of evolutionary theory for sex allocation has been supported by experiments demonstrating that malaria parasites adjust their sex ratios in response to infection genetic diversity, precisely as predicted. Theory also predicts that parasites should adjust sex allocation in response to host immunity. Whilst data are supportive, the assumptions underlying this prediction - that host immune responses have differential effects on the mating ability of males and females - have not yet been tested. Here, we combine experimental work with theoretical models in order to investigate whether the development and fertility of male and female parasites is affected by innate immune factors and develop new theory to predict how parasites' sex allocation strategies should evolve in response to the observed effects. Specifically, we demonstrate that reactive nitrogen species impair gametogenesis of males only, but reduce the fertility of both male and female gametes. In contrast, tumour necrosis factor-α does not influence gametogenesis in either sex but impairs zygote development. Therefore, our experiments demonstrate that immune factors have complex effects on each sex, ranging from reducing the ability of gametocytes to develop into gametes, to affecting the viability of offspring. We incorporate these results into theory to predict how the evolutionary trajectories of parasite sex ratio strategies are shaped by sex differences in gamete production, fertility and offspring development. We show that medical interventions targeting offspring development are more likely

  15. Does the mechanism of sex determination constrain the potential for sex manipulation? A test in geckos with contrasting sex-determining systems

    Science.gov (United States)

    Kratochvíl, Lukáš; Kubička, Lukáš; Landová, Eva

    2008-03-01

    The concentration of yolk steroids was suggested to influence offspring gender in oviparous animals subject to both temperature-dependent sex determination (TSD) and genotypic sex determination (GSD). However, the proposed mechanisms of steroid effects are thought to differ between TSD and GSD: a direct effect of oestrogens on gonad feminisation in TSD species vs a differential induction of male-producing or female-producing gametes in GSD species. Geckos offer an ideal opportunity for testing these suggested mechanisms. Closely related gecko species differ in their modes of sex determination. They lay clutches of two synchronously formed eggs; both eggs share equal steroid levels. If identical hormonal composition and environment during vitellogenesis, gravidity and incubation determine the sex of the progeny, siblings should share the same gender in both TSD and GSD geckos. We found strong support for this prediction in a TSD gecko species. Among clutches that were incubated at the temperature that produced both sexes, there were no clutches with siblings of the opposite sex. On the other hand, about half of the clutches yielded siblings of the opposite sex in four GSD species. These results suggest that sex-determining systems constrain the ability of the female to produce single-sex siblings and, hence, it seems that the GSD mechanism constrains the opportunities for sex ratio manipulation in geckos via yolk steroid manipulation.

  16. Examination of relaxin and its receptors expression in pig gametes and embryos

    Directory of Open Access Journals (Sweden)

    Bathgate Ross A

    2011-01-01

    Full Text Available Abstract Background Relaxin is a small peptide also known as pregnancy hormone in many mammals. It is synthesized by both male and female tissues, and its secretions are found in various body fluids such as plasma serum, ovarian follicular fluid, utero-oviduct secretions, and seminal plasma of many mammals, including pigs. However, the presence and effects of relaxin in porcine gametes and embryos are still not well-known. The purpose of this study was to assess the presence of relaxin and its receptors RXFP1 and RXFP2 in pig gametes and embryos. Methods Immature cumulus-oocyte complexes (COCs were aspirated from sows' ovaries collected at the abattoir. After in vitro-maturation, COCs were in vitro-fertilized and cultured. For studies, immature and mature COCs were separately collected, and oocytes were freed from their surrounding cumulus cells. Denuded oocytes, cumulus cells, mature boar spermatozoa, zygotes, and embryos (cleaved and blastocysts were harvested for temporal and spatial gene expression studies. Sections of ovary, granulosa and neonatal porcine uterine cells were also collected to use as controls. Results Using both semi-quantitative and quantitative PCRs, relaxin transcripts were not detected in all tested samples, while RXFP1 and RXFP2 mRNA were present. Both receptor gene products were found at higher levels in oocytes compared to cumulus cells, irrespective of the maturation time. Cleaved-embryos contained higher levels of RXFP2 mRNA, whereas, blastocysts were characterized by a higher RXFP1 mRNA content. Using western-immunoblotting or in situ immunofluorescence, relaxin and its receptor proteins were detected in all samples. Their fluorescence intensities were consistently more important in mature oocytes than immature ones. The RXFP1 and RXFP2 signal intensities were mostly located in the plasma membrane region, while the relaxin ones appeared homogeneously distributed within the oocytes and embryonic cells. Furthermore

  17. "I am Your Mother and Your Father!" In Vitro Derived Gametes and the Ethics of Solo Reproduction.

    Science.gov (United States)

    Cutas, Daniela; Smajdor, Anna

    2017-12-01

    In this paper, we will discuss the prospect of human reproduction achieved with gametes originating from only one person. According to statements by a minority of scientists working on the generation of gametes in vitro, it may become possible to create eggs from men's non-reproductive cells and sperm from women's. This would enable, at least in principle, the creation of an embryo from cells obtained from only one individual: 'solo reproduction'. We will consider what might motivate people to reproduce in this way, and the implications that solo reproduction might have for ethics and policy. We suggest that such an innovation is unlikely to revolutionise reproduction and parenting. Indeed, in some respects it is less revolutionary than in vitro fertilisation as a whole. Furthermore, we show that solo reproduction with in vitro created gametes is not necessarily any more ethically problematic than gamete donation-and probably less so. Where appropriate, we draw parallels with the debate surrounding reproductive cloning. We note that solo reproduction may serve to perpetuate reductive geneticised accounts of reproduction, and that this may indeed be ethically questionable. However, in this it is not unique among other technologies of assisted reproduction, many of which focus on genetic transmission. It is for this reason that a ban on solo reproduction might be inconsistent with continuing to permit other kinds of reproduction that also bear the potential to strengthen attachment to a geneticised account of reproduction. Our claim is that there are at least as good reasons to pursue research towards enabling solo reproduction, and eventually to introduce solo reproduction as an option for fertility treatment, as there are to do so for other infertility related purposes.

  18. Influences of DMP on the fertilization process and subsequent embryogenesis of abalone (Haliotis diversicolor supertexta by gametes exposure.

    Directory of Open Access Journals (Sweden)

    Jin Zhou

    Full Text Available Di-methyl phthalate (DMP, a typical endocrine disrupting chemical (EDC, is ubiquitously distributed in aquatic environments; yet studies regarding its impact on gametes and the resulting effects on embryogenesis in marine gastropods are relatively scarce. In this study, the influences of DMP on the gametes and subsequent developmental process of abalone (Haliotis diversicolor supertexta, a representative marine benthic gastropod were assessed. Newborn abalone eggs and sperm were exposed separately to different DMP concentrations (1, 10 or 100 ppb for 60 min. At the end-point of exposure, the DMP-treated eggs and sperm were collected for analysis of their ultra-structures, ATPase activities and total lipid levels, and the fertilized gametes (embryos were collected to monitor related reproductive parameters (fertilization rate, abnormal development rate and hatching success rate. Treatment with DMP did not significantly alter the structure or total lipid content of eggs at any of the doses tested. Hatching failures and morphological abnormalities were only observed with the highest dose of DMP (100 ppb. However, DMP exposure did suppress sperm ATPase activities and affect the morphological character of their mitochondria. DMP-treated sperm exhibited dose-dependent decreases in fertilization efficiency, morphogenesis and hatchability. Relatively obvious toxicological effects were observed when both sperm and eggs were exposed to DMP. Furthermore, RT-PCR results indicate that treatment of gametes with DMP changed the expression patterns of physiologically-regulated genes (cyp3a, 17β-HSD-11 and 17β-HSD-12 in subsequent embryogenesis. Taken together, this study proofed that pre-fertilization exposure of abalone eggs, sperm or both to DMP adversely affects the fertilization process and subsequent embryogenesis.

  19. Gamete donors' reasons for, and expectations and experiences of, registration with a voluntary donor linking register.

    Science.gov (United States)

    Blyth, Eric; Crawshaw, Marilyn; Frith, Lucy; van den Akker, Olga

    2017-12-01

    This paper reports on a study of the views and experiences of 21 sperm donors and five egg donors registered with UK DonorLink (UKDL), a voluntary DNA-based contact register established to facilitate contact between adults who wish to identify and locate others to whom they are genetically related following donor conception. Specifically, the paper examines donors' reasons for searching for, or making information about themselves available to donor-conceived offspring. Their expectations of registration with UKDL, experiences of being registered and finally, the experiences of those who had contacted donor-conceived offspring and other genetic relatives are investigated. While most respondents reported largely positive experiences of registration, the study found significant issues relating to concerns about donation, DNA testing, possible linking with offspring and expectations of any relationship that might be established with offspring that have implications for support, mediation and counselling. Research that puts the experiences, perceptions and interests of gamete donors as the central focus of study is a relatively recent phenomenon. This study contributes to this debate and highlights directions for future research in this area.

  20. Vertical transmission of Prunus necrotic ringspot virus: hitch-hiking from gametes to seedling.

    Science.gov (United States)

    Amari, Khalid; Burgos, Lorenzo; Pallás, Vicente; Sánchez-Pina, Maria Amelia

    2009-07-01

    The aim of this work was to follow Prunus necrotic ringspot virus (PNRSV) infection in apricot reproductive tissues and transmission of the virus to the next generation. For this, an analysis of viral distribution in apricot reproductive organs was carried out at different developmental stages. PNRSV was detected in reproductive tissues during gametogenesis. The virus was always present in the nucellus and, in some cases, in the embryo sac. Studies within infected seeds at the embryo globular stage revealed that PNRSV infects all parts of the seed, including embryo, endosperm and testa. In the torpedo and bent cotyledon developmental stages, high concentrations of the virus were detected in the testa and endosperm. At seed maturity, PNRSV accumulated slightly more in the embryo than in the cotyledons. In situ hybridization showed the presence of PNRSV RNA in embryos obtained following hand-pollination of virus-free pistils with infected pollen. Interestingly, tissue-printing from fruits obtained from these pistils showed viral RNA in the periphery of the fruits, whereas crosses between infected pistils and infected pollen resulted in a total invasion of the fruits. Taken together, these results shed light on the vertical transmission of PNRSV from gametes to seedlings.

  1. Strategies for locating the female gamete: the importance of measuring sperm trajectories in three spatial dimensions

    Science.gov (United States)

    Guerrero, Adán; Carneiro, Jorge; Pimentel, Arturo; Wood, Christopher D.; Corkidi, Gabriel; Darszon, Alberto

    2011-01-01

    The spermatozoon must find its female gamete partner and deliver its genetic material to generate a new individual. This requires that the spermatozoon be motile and endowed with sophisticated swimming strategies to locate the oocyte. A common strategy is chemotaxis, in which spermatozoa detect and follow a gradient of chemical signals released by the egg and its associated structures. Decoding the female gamete’s positional information is a process that spermatozoa undergo in a three-dimensional (3D) space; however, due to their speed and small size, this process has been studied almost exclusively in spermatozoa restricted to swimming in two dimensions (2D). This review examines the relationship between the mechanics of sperm propulsion and the physiological function of these cells in 3D. It also considers whether it is possible to derive all the 3D sperm swimming characteristics by extrapolating from 2D measurements. It is concluded that full insight into flagellar beat dynamics, swimming paths and chemotaxis under physiological conditions will eventually require quantitative imaging of flagellar form, ion flux changes, cell trajectories and modelling of free-swimming spermatozoa in 3D. PMID:21642645

  2. Arabidopsis female gametophyte gene expression map reveals similarities between plant and animal gametes.

    Science.gov (United States)

    Wuest, Samuel E; Vijverberg, Kitty; Schmidt, Anja; Weiss, Manuel; Gheyselinck, Jacqueline; Lohr, Miriam; Wellmer, Frank; Rahnenführer, Jörg; von Mering, Christian; Grossniklaus, Ueli

    2010-03-23

    The development of multicellular organisms is controlled by differential gene expression whereby cells adopt distinct fates. A spatially resolved view of gene expression allows the elucidation of transcriptional networks that are linked to cellular identity and function. The haploid female gametophyte of flowering plants is a highly reduced organism: at maturity, it often consists of as few as three cell types derived from a common precursor [1, 2]. However, because of its inaccessibility and small size, we know little about the molecular basis of cell specification and differentiation in the female gametophyte. Here we report expression profiles of all cell types in the mature Arabidopsis female gametophyte. Differentially expressed posttranscriptional regulatory modules and metabolic pathways characterize the distinct cell types. Several transcription factor families are overrepresented in the female gametophyte in comparison to other plant tissues, e.g., type I MADS domain, RWP-RK, and reproductive meristem transcription factors. PAZ/Piwi-domain encoding genes are upregulated in the egg, indicating a role of epigenetic regulation through small RNA pathways-a feature paralleled in the germline of animals [3]. A comparison of human and Arabidopsis egg cells for enrichment of functional groups identified several similarities that may represent a consequence of coevolution or ancestral gametic features. 2010 Elsevier Ltd. All rights reserved.

  3. Expression and localization of tubulin cofactors TBCD and TBCE in human gametes.

    Science.gov (United States)

    Jiménez-Moreno, Victoria; Agirregoitia, Ekaitz

    2017-06-01

    The tubulin cofactors TBCD and TBCE play an essential role in regulation of the microtubule dynamics in a wide variety of somatic cells, but little information is known about the expression of these cofactors in human sperm and oocytes. In this study, we focused on the investigation of the presence of, and the differential distribution of, the tubulin cofactors TBCD and TBCE in human sperm and during human oocyte maturation. We performed expression assays for TBCD and TBCE by reverse transcription-polymerase chain reaction (RT-PCR), western blot and immunofluorescence and verified the presence of both cofactors in human gametes. TBCD and TBCE were located mainly in the middle region and in the tail of the sperm while in the oocyte the localization was cytosolic. The mRNA of both tubulin cofactors were present in the human oocytes but not in sperm cells. This finding gives a first insight into where TBCD and TBCE could carry out their function in the continuous changes that the cytoskeleton experiences during gametogenesis and also prior to fertilization.

  4. Regulating Gamete Donation in the U.S.: Ethical, Legal and Social Implications

    Directory of Open Access Journals (Sweden)

    Maya Sabatello

    2015-07-01

    Full Text Available This article explores the practice of gamete donation in the U.S. having in mind the larger question of what do we as a society owe children born as a result (donor-conceived children. Do recipient-parents have a duty to tell their donor-conceived child about his/her genetic origins? Should the identity of the donor be disclosed or remain anonymous? Does the child have a right to know her conception story and to receive information, including identifying information, about the donor? Furthermore, if a donor-conceived child has a right to know, who has the duty to tell her/him about it? The Article underscores the ethical, legal and social dilemmas that arise, comparing and contrasting with international developments in this arena. It highlights the market-based and more specific medical justifications for regulating this field, explores the emerging so-called right of the child to know his/her genetic origins (“the right to know”, and considers the challenges such a right evokes to existing legal culture and principles of medical ethics in the U.S. as well as other broader societal implications of such a right.

  5. Regulating Gamete Donation in the U.S.: Ethical, Legal and Social Implications.

    Science.gov (United States)

    Sabatello, Maya

    2015-09-01

    This article explores the practice of gamete donation in the U.S. having in mind the larger question of what do we as a society owe children born as a result (donor-conceived children). Do recipient-parents have a duty to tell their donor-conceived child about his/her genetic origins? Should the identity of the donor be disclosed or remain anonymous? Does the child have a right to know her conception story and to receive information, including identifying information, about the donor? Furthermore, if a donor-conceived child has a right to know, who has the duty to tell her/him about it? The Article underscores the ethical, legal and social dilemmas that arise, comparing and contrasting with international developments in this arena. It highlights the market-based and more specific medical justifications for regulating this field, explores the emerging so-called right of the child to know his/her genetic origins ("the right to know"), and considers the challenges such a right evokes to existing legal culture and principles of medical ethics in the U.S. as well as other broader societal implications of such a right.

  6. The Role of Peroxisome Proliferator-Activated Receptors in the Development and Physiology of Gametes and Preimplantation Embryos

    Directory of Open Access Journals (Sweden)

    Jaou-Chen Huang

    2008-01-01

    Full Text Available In several species, a family of nuclear receptors, the peroxisome proliferator-activated receptors (PPARs composed of three isotypes, is expressed in somatic cells and germ cells of the ovary as well as the testis. Invalidation of these receptors in mice or stimulation of these receptors in vivo or in vitro showed that each receptor has physiological roles in the gamete maturation or the embryo development. In addition, synthetic PPARγ ligands are recently used to induce ovulation in women with polycystic ovary disease. These results reveal the positive actions of PPAR in reproduction. On the other hand, xenobiotics molecules (in herbicides, plasticizers, or components of personal care products, capable of activating PPAR, may disrupt normal PPAR functions in the ovary or the testis and have consequences on the quality of the gametes and the embryos. Despite the recent data obtained on the biological actions of PPARs in reproduction, relatively little is known about PPARs in gametes and embryos. This review summarizes the current knowledge on the expression and the function of PPARs as well as their partners, retinoid X receptors (RXRs, in germ cells and preimplantation embryos. The effects of natural and synthetic PPAR ligands will also be discussed from the perspectives of reproductive toxicology and assisted reproductive technology.

  7. Consecutive five-year analysis of paternal and maternal gene flow and contributions of gametic heterogeneities to overall genetic composition of dispersed seeds of Pinus densiflora (Pinaceae).

    Science.gov (United States)

    Iwaizumi, Masakazu G; Takahashi, Makoto; Isoda, Keiya; Austerlitz, Frédéric

    2013-09-01

    Genetic variability in monoecious woody plant populations results from the assemblage of individuals issued from asymmetrical male and female reproductive functions, produced during spatially and temporarily heterogeneous reproductive and dispersal events. Here we investigated the dispersal patterns and levels of genetic diversity and differentiation of both paternal and maternal gametes in a natural population of Pinus densiflora at the multiple-year scale as long as five consecutive years. • We analyzed the paternity and maternity for 1576 seeds and 454 candidate adult trees using nuclear DNA polymorphisms of diploid biparental embryos and haploid maternal megagametophytes at eight microsatellite loci. • Despite the low levels of genetic differentiation among gamete groups, a two-way AMOVA analysis showed that the parental origin (paternal vs. maternal gametes), the year of gamete production and their interaction had significant effects on the genetic composition of the seeds. While maternal gamete groups showed a significant FST value across the 5 years, this was not true for their paternal counterparts. Within the population, we found that the relative reproductive contributions of the paternal vs. the maternal parent differed among adult trees, the maternal contributions showing a larger year-to-year fluctuation. • The overall genetic variability of dispersed seeds appeared to result from two sources of heterogeneity: the difference between paternal and maternal patterns of reproduction and gamete dispersal and year-to-year heterogeneity of reproduction of adult trees, especially in their maternal reproduction.

  8. Conundrums with penumbras: the right to privacy encompasses non-gamete providers who create preembryos with the intent to become parents.

    Science.gov (United States)

    Dillon, Lainie M C

    2003-05-01

    To date, five state high courts have resolved disputes over frozen preembryos. These disputes arose during divorce proceedings between couples who had previously used assisted reproduction and cryopreserved excess preembryos. In each case, one spouse wished to have the preembryos destroyed, while the other wanted to be able to use or donate them in the future. The parties in these cases invoked the constitutional right to privacy to argue for dispositional control over the preembryos; two of the five cases were resolved by relying on this right. The constitutional right to privacy protects intimate decisions involving procreation, marriage, and family life. However, when couples use donated sperm or ova to create preembryos, a unique circumstance arises: one spouse--the gamete provider--is genetically related to the preembryos and the other is not. If courts resolve frozen preembryo disputes that involve non-gamete providers based on the constitutional right to privacy, they should find that the constitutional right to privacy encompasses the interests of both gamete and non-gamete providers. Individuals who create preembryos with the intent to become a parent have made an intimate decision involving procreation, marriage, and family life that falls squarely within the the right to privacy. In such cases, the couple together made the decision to create a family through the use of assisted reproduction, and the preembryos would not exist but for that joint decision. Therefore, gamete and non-gamete providers should be afforded equal constitutional protection in disputes over frozen preembryos.

  9. Mating behaviour and gamete release in gilthead seabream (Sparus aurata, Linnaeus 1758) held in captivity

    Energy Technology Data Exchange (ETDEWEB)

    Ibarra-Zatarain, Z.; Duncan, N.

    2015-07-01

    The present study aimed to describe the reproductive behaviour of gilthead seabream (Sparus aurata) in captivity. Twenty-four mature gilthead seabream, divided in two tanks, were utilized for the present study. Reproductive behaviour was recorded using submersibles cameras. A total of 67 spawning events were analysed. The mean duration time that gilthead seabream spent spawning was 54 ± 4 min/day, during which mean number of individual spawning events was 5.6 ± 0.2. The mean volume of eggs produced by both broodstocks was 405 ± 13.4 mL with a fertilization rate of 91.6 ± 0.4%. The reproductive behaviour began with a schooling behaviour and then forming light aggregations. From an aggregation or an encounter while swimming freely a female initiated a spawning rush followed by one or more males to gametes liberation. The spawning rush was brief, 1.6 ± 0.5 sec, over an approximately 1.7 ± 0.2 m distance from the tank bottom to the water surface. Pair spawning, between a single female and male, was the most common (71.6%). Group spawning was less common and involved a single female spawning with two males (22.5%) or three males (4.9%). Spawning rushes involving more than one female were not observed. Gilthead seabream in the present study presented a tendency to pair spawn and eggs collected as a “spawn” were actually the sum of many separate spawning events over a short time period. This is the first description of gilthead seabream spawning and the findings help to understand microsatellite based observations of spawning kinetics. (Author)

  10. Expression of a type B RIFIN in Plasmodium falciparum merozoites and gametes

    Directory of Open Access Journals (Sweden)

    Mwakalinga Steven B

    2012-12-01

    Full Text Available Abstract Background The ability of Plasmodium falciparum to undergo antigenic variation, by switching expression among protein variants encoded by multigene families, such as var, rif and stevor, is key to the survival of this parasite in the human host. The RIFIN protein family can be divided into A and B types based on the presence or absence of a 25 amino acid motif in the semi-conserved domain. A particular type B RIFIN, PF13_0006, has previously been shown to be strongly transcribed in the asexual and sexual stages of P. falciparum in vitro. Methods Antibodies to recombinant PF13_0006 RIFIN were used in immunofluorescence and confocal imaging of 3D7 parasites throughout the asexual reproduction and sexual development to examine the expression of PF13_0006. Furthermore, reactivity to recombinant PF13_0006 was measured in plasma samples collected from individuals from both East and West African endemic areas. Results The PF13_0006 RIFIN variant appeared expressed by both released merozoites and gametes after emergence. 7.4% and 12.1% of individuals from East and West African endemic areas, respectively, carry plasma antibodies that recognize recombinant PF13_0006, where the antibody responses were more common among older children. Conclusions The stage specificity of PF13_0006 suggests that the diversity of RIFIN variants has evolved to provide multiple specialized functions in different stages of the parasite life cycle. These data also suggest that RIFIN variants antigenically similar to PF13_0006 occur in African parasite populations.

  11. Selling blood and gametes during tough economic times: insights from Google search.

    Science.gov (United States)

    Wu, Jonathan A; Ngo, Tin C; Rothman, Cappy; Breyer, Benjamin N; Eisenberg, Michael L

    2015-10-01

    To use Google Insights search volume and publicly available economic indicators to test the hypothesis that sperm, egg, and blood donations increase during economic downturns and to demonstrate the feasibility of using Google search volume data to predict national trends in actual sperm, egg, and blood donations rates. Cross-correlation statistical analysis comparing Google search data for terms relating to blood, egg, and sperm donations with various economic indicators including the S&P 500 closing values, gross domestic product (GDP), the U.S. Index of Leading Indicators (U.S. Leading Index), gross savings rate, mortgage interest rates, unemployment rate, and consumer price index (CPI) from 2004-2011. A secondary analysis determined the Pearson correlation coefficient between Google search data with actual sperm, egg, and blood donation volume in the U.S. as measured by California Cryobank, the National Assisted Reproductive Technology Surveillance System, and the National Blood Collection and Utilization Survey, respectively. Significance of cross-correlation and Pearson correlation analysis as indicated by p value. There were several highly significant cross-correlation relationships between search volume and various economic indicators. Correlation between Google search volume for the term 'sperm donation,' 'egg donation,' and 'blood donation' with actual number of sperm, egg and blood donations in the United States demonstrated Pearson correlation coefficients of 0.2 (p > 0.10), -0.1 (p > 0.10), and 0.07 (p > 0.10), respectively. Temporal analysis showed an improved correlation coefficient of 0.9 (p Google search volume. Google search volume data for search terms relating to sperm, egg, and blood donation increase during economic downturns. This finding suggests gamete and bodily fluid donations are influenced by market forces like other commodities. Google search may be useful for predicting blood donation trends but is more limited in predicting actual

  12. Sex Headaches

    Science.gov (United States)

    Sex headaches Overview Sex headaches are brought on by sexual activity — especially an orgasm. You may notice a dull ache in your head ... severe headache just before or during orgasm. Most sex headaches are nothing to worry about. But some ...

  13. The Effect of Filamentous Turf Algal Removal on the Development of Gametes of the Coral Orbicella annularis

    Science.gov (United States)

    Cetz-Navarro, Neidy P.; Carpizo-Ituarte, Eugenio J.; Espinoza-Avalos, Julio; Chee-Barragán, Guillermina

    2015-01-01

    Macroalgae and filamentous turf algae (FTA) are abundant on degraded coral reefs, and the reproductive responses of corals may indicate sub-lethal stress under these conditions. The percentage of gametogenic stages (PGS) and the maximum diameter of eggs (MDE; or egg size) of Orbicella annularis were used to evaluate the effect of long- (7–10 months) and short-term (2.5 months) FTA removal (treatments T1 and T2, respectively) at both the beginning (May) and the end (August) of gametogenesis. Ramets (individual lobes of a colony) surrounded by FTA (T3) or crustose coralline algae (CCA; T4) were used as controls. The removal of FTA enhanced the development of gametes (i.e., a larger and higher percentage of mature gametes (PMG)) of O. annularis for T1 vs. T3 ramets in May and T1 and T2 vs. T3 ramets in August. Similar values of PGS and MDE between gametes from T3 and T4 in both May and August were unexpected because a previous study had shown that the same ramets of T4 (with higher tissue thickness, chlorophyll a cm-2 and zooxanthellae density and lower mitotic index values) were less stressed than ramets of T3. Evaluating coral stress through reproduction can reveal more sensitive responses than other biological parameters; within reproductive metrics, PGS can be a better stress indicator than egg size. The presence of turf algae strongly impacted the development of gametes and egg size (e.g., PMG in ramets with FTA removal increased almost twofold in comparison with ramets surrounded by FTA in August), most likely exerting negative chronic effects in the long run due to the ubiquity and permanence of turf algae in the Caribbean. These algae can be considered a stressor that affects coral sexual reproduction. Although the effects of turf algae on O. annularis are apparently less severe than those of other stressors, the future of this species is uncertain because of the combined impacts of these effects, the decline of O. annularis populations and the almost

  14. Hormonal induction of gamete release, and in-vitro fertilisation, in the critically endangered Southern Corroboree Frog, Pseudophryne corroboree

    Directory of Open Access Journals (Sweden)

    Silla Aimee J

    2010-11-01

    Full Text Available Abstract Background Conservation Breeding Programs (CBP's are playing an important role in the protection of critically endangered anuran amphibians, but for many species recruitment is not successful enough to maintain captive populations, or provide individuals for release. In response, there has been an increasing focus on the use of Assisted Reproductive Technologies (ART, including the administration of reproductive hormones to induce gamete release followed by in vitro fertilisation. The objective of this study was to test the efficacy of two exogenous hormones to induce gamete release, for the purpose of conducting in vitro fertilisation (IVF, in one of Australia's most critically endangered frog species, Pseudophryne corroboree. Methods Male frogs were administered a single dose of either human chorionic gonadotropin (hCG or luteinizing hormone-releasing hormone (LHRHa, while female frogs received both a priming and ovulatory dose of LHRHa. Spermiation responses were evaluated at 3, 7, 12, 24, 36, 48, 60 and 72 h post hormone administration (PA, and sperm number and viability were quantified using fluorescent microscopy. Ovulation responses were evaluated by stripping females every 12 h PA for 5 days. Once gametes were obtained, IVF was attempted by combining spermic urine with oocytes in a dilute solution of simplified amphibian ringer (SAR. Results Administration of both hCG and LHRHa induced approximately 80% of males to release sperm over 72 h. Peak sperm release occurred at 12 h PA for hCG treated males and 36 h PA for LHRHa treated males. On average, LHRHa treated males released a significantly higher total number of live sperm, and a higher concentration of sperm, over a longer period. In female frogs, administration of LHRHa induced approximately 30% of individuals to release eggs. On average, eggs were released between 24 and 48 h PA, with a peak in egg release at 36 h PA. IVF resulted in a moderate percentage (54.72% of eggs

  15. The effect of filamentous turf algal removal on the development of gametes of the coral Orbicella annularis.

    Directory of Open Access Journals (Sweden)

    Neidy P Cetz-Navarro

    Full Text Available Macroalgae and filamentous turf algae (FTA are abundant on degraded coral reefs, and the reproductive responses of corals may indicate sub-lethal stress under these conditions. The percentage of gametogenic stages (PGS and the maximum diameter of eggs (MDE; or egg size of Orbicella annularis were used to evaluate the effect of long- (7-10 months and short-term (2.5 months FTA removal (treatments T1 and T2, respectively at both the beginning (May and the end (August of gametogenesis. Ramets (individual lobes of a colony surrounded by FTA (T3 or crustose coralline algae (CCA; T4 were used as controls. The removal of FTA enhanced the development of gametes (i.e., a larger and higher percentage of mature gametes (PMG of O. annularis for T1 vs. T3 ramets in May and T1 and T2 vs. T3 ramets in August. Similar values of PGS and MDE between gametes from T3 and T4 in both May and August were unexpected because a previous study had shown that the same ramets of T4 (with higher tissue thickness, chlorophyll a cm-2 and zooxanthellae density and lower mitotic index values were less stressed than ramets of T3. Evaluating coral stress through reproduction can reveal more sensitive responses than other biological parameters; within reproductive metrics, PGS can be a better stress indicator than egg size. The presence of turf algae strongly impacted the development of gametes and egg size (e.g., PMG in ramets with FTA removal increased almost twofold in comparison with ramets surrounded by FTA in August, most likely exerting negative chronic effects in the long run due to the ubiquity and permanence of turf algae in the Caribbean. These algae can be considered a stressor that affects coral sexual reproduction. Although the effects of turf algae on O. annularis are apparently less severe than those of other stressors, the future of this species is uncertain because of the combined impacts of these effects, the decline of O. annularis populations and the almost

  16. 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 ...

  17. Ocean acidification hampers sperm-egg collisions, gamete fusion, and generation of Ca2+ oscillations of a broadcast spawning bivalve, Tegillarca granosa.

    Science.gov (United States)

    Shi, Wei; Han, Yu; Guo, Cheng; Zhao, Xinguo; Liu, Saixi; Su, Wenhao; Wang, Yichen; Zha, Shanjie; Chai, Xueliang; Liu, Guangxu

    2017-09-01

    Although the effect of ocean acidification on fertilization success of marine organisms is increasingly well documented, the underlying mechanisms are not completely understood. The fertilization success of broadcast spawning invertebrates depends on successful sperm-egg collisions, gamete fusion, and standard generation of Ca 2+ oscillations. Therefore, the realistic effects of future ocean pCO 2 levels on these specific aspects of fertilization of Tegillarca granosa were investigated in the present study through sperm velocity trials, fertilization kinetics model analysis, and intracellular Ca 2+ assays, respectively. Results obtained indicated that ocean acidification significantly reduced the fertilization success of T. granosa, which could be accountable by (i) decreased sperm velocity hence reducing the probability for sperm-egg collisions; (ii) lowered probability of gamete fusion for each gamete collision event; and (iii) disrupted intracellular Ca 2+ oscillations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Protection against de novo methylation is instrumental in maintaining parent-of-origin methylation inherited from the gametes.

    Science.gov (United States)

    Proudhon, Charlotte; Duffié, Rachel; Ajjan, Sophie; Cowley, Michael; Iranzo, Julian; Carbajosa, Guillermo; Saadeh, Heba; Holland, Michelle L; Oakey, Rebecca J; Rakyan, Vardhman K; Schulz, Reiner; Bourc'his, Déborah

    2012-09-28

    Identifying loci with parental differences in DNA methylation is key to unraveling parent-of-origin phenotypes. By conducting a MeDIP-Seq screen in maternal-methylation free postimplantation mouse embryos (Dnmt3L-/+), we demonstrate that maternal-specific methylation exists very scarcely at midgestation. We reveal two forms of oocyte-specific methylation inheritance: limited to preimplantation, or with longer duration, i.e. maternally imprinted loci. Transient and imprinted maternal germline DMRs (gDMRs) are indistinguishable in gametes and preimplantation embryos, however, de novo methylation of paternal alleles at implantation delineates their fates and acts as a major leveling factor of parent-inherited differences. We characterize two new imprinted gDMRs, at the Cdh15 and AK008011 loci, with tissue-specific imprinting loss, again by paternal methylation gain. Protection against demethylation after fertilization has been emphasized as instrumental in maintaining parent-of-origin methylation inherited from the gametes. Here we provide evidence that protection against de novo methylation acts as an equal major pivot, at implantation and throughout life. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Induced pluripotent stem cell-derived gamete-associated proteins incite rejection of induced pluripotent stem cells in syngeneic mice.

    Science.gov (United States)

    Kim, Eun-Mi; Manzar, Gohar; Zavazava, Nicholas

    2017-06-01

    The safety of induced pluripotent stem cells (iPSCs) in autologous recipients has been questioned after iPSCs, but not embryonic stem cells (ESCs), were reported to be rejected in syngeneic mice. This important topic has remained controversial because there has not been a mechanistic explanation for this phenomenon. Here, we hypothesize that iPSCs, but not ESCs, readily differentiate into gamete-forming cells that express meiotic antigens normally found in immune-privileged gonads. Because peripheral blood T cells are not tolerized to these antigens in the thymus, gamete-associated-proteins (GAPs) sensitize T cells leading to rejection. Here, we provide evidence that GAPs expressed in iPSC teratomas, but not in ESC teratomas, are responsible for the immunological rejection of iPSCs. Furthermore, silencing the expression of Stra8, 'the master regulator of meiosis', in iPSCs, using short hairpin RNA led to significant abrogation of the rejection of iPSCs, supporting our central hypothesis that GAPs expressed after initiation of meiosis in iPSCs were responsible for rejection. In contrast to iPSCs, iPSC-derivatives, such as haematopoietic progenitor cells, are able to engraft long-term into syngeneic recipients because they no longer express GAPs. Our findings, for the first time, provide a unifying explanation of why iPSCs, but not ESCs, are rejected in syngeneic recipients, ending the current controversy on the safety of iPSCs and their derivatives. © 2017 John Wiley & Sons Ltd.

  20. Genetic mapping of centromeres in the nine Citrus clementina chromosomes using half-tetrad analysis and recombination patterns in unreduced and haploid gametes.

    Science.gov (United States)

    Aleza, Pablo; Cuenca, José; Hernández, María; Juárez, José; Navarro, Luis; Ollitrault, Patrick

    2015-03-08

    Mapping centromere locations in plant species provides essential information for the analysis of genetic structures and population dynamics. The centromere's position affects the distribution of crossovers along a chromosome and the parental heterozygosity restitution by 2n gametes is a direct function of the genetic distance to the centromere. Sexual polyploidisation is relatively frequent in Citrus species and is widely used to develop new seedless triploid cultivars. The study's objectives were to (i) map the positions of the centromeres of the nine Citrus clementina chromosomes; (ii) analyse the crossover interference in unreduced gametes; and (iii) establish the pattern of genetic recombination in haploid clementine gametes along each chromosome and its relationship with the centromere location and distribution of genic sequences. Triploid progenies were derived from unreduced megagametophytes produced by second-division restitution. Centromere positions were mapped genetically for all linkage groups using half-tetrad analysis. Inference of the physical locations of centromeres revealed one acrocentric, four metacentric and four submetacentric chromosomes. Crossover interference was observed in unreduced gametes, with variation seen between chromosome arms. For haploid gametes, a strong decrease in the recombination rate occurred in centromeric and pericentromeric regions, which contained a low density of genic sequences. In chromosomes VIII and IX, these low recombination rates extended beyond the pericentromeric regions. The genomic region corresponding to a genetic distance recombination pattern along each chromosome. However, regions with low recombination rates extended beyond the pericentromeric regions of some chromosomes into areas richer in genic sequences. The persistence of strong linkage disequilibrium between large numbers of genes promotes the stability of epistatic interactions and multilocus-controlled traits over successive generations but

  1. Creating Sex

    DEFF Research Database (Denmark)

    Cahana, Jonathan

    2016-01-01

    Thomas Laqueur’s influential yet controversial study Making Sex has, in many ways, revolutionized our understanding of sexuality in antiquity. Yet, most of Laqueur’s critics and supporters stressed the one-sex body, while the crux of his argument is the primacy of gender. Moreover, a systematic...

  2. Sex determination

    Indian Academy of Sciences (India)

    The sex-determining system differs considerably among organisms. Even among insect species, the genetic system for sex-determination is highly diversified. In Drosophila melanogaster, somatic sexual differentiation is regulated by a well characterized genetic hierarchy X : A > Sxl > tra/tra2 > dsx and fru. This cascade ...

  3. Couples with non-obstructive azoospermia are interested in future treatments with artificial gametes.

    Science.gov (United States)

    Hendriks, S; Hessel, M; Mochtar, M H; Meissner, A; van der Veen, F; Repping, S; Dancet, E A F

    2016-08-01

    Would couples diagnosed with non-obstructive azoospermia (NOA) consider two future treatments with artificial gametes (AGs) as alternatives for testicular sperm extraction followed by ICSI (TESE-ICSI)? Most couples with NOA (89%) would opt for treatment with AGs before attempting TESE-ICSI and/or after failed TESE-ICSI. Couples with NOA who undergo TESE-ICSI have a 25% chance of conceiving a child. Two future treatments that are being developed are 'ICSI with artificial sperm formed from somatic cells' (ICSI with AGs) and 'natural conception after autotransplantation of in vitro proliferated spermatogonial stem cells' (natural conception with AGs). It is unknown what treatment preferences patients have. A cross-sectional survey conducted in 2012-2013, addressing all 921 couples diagnosed with NOA and treated with TESE-ICSI in Dutch fertility clinics between 2007 and 2012. The coded questionnaires were sent by mail and followed up with two reminders. We developed the questionnaire based on a literature review and previous qualitative interviews, and included treatment preference and the valuation of nine treatment characteristics. We assessed reliability of the questionnaires and calculated mean importance scores (MISs: 0-10) of each treatment characteristic. We assessed which patient and treatment characteristics were associated with a couple's hypothetical treatment preference using binominal regression. The vast majority (89%) of the 494 responding couples (response rate: 54%) would potentially opt for AGs as a first and/or a last resort treatment option. More specifically, as a first treatment couples were likely (67%) to prefer natural conception with AGs over TESE-ICSI and less likely to prefer ICSI with AGs over TESE-ICSI (34%). After failed TESE-ICSI, the majority of couples (75%) would want to attempt ICSI with AGs as a last resort option. The most important characteristics of treatment were safety for children (MIS: 8.2), pregnancy rates (MIS: 7.7) and

  4. 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.

  5. Sex-linkage of two enzyme loci in Oncorhyncus mykiss (rainbow trout)

    Science.gov (United States)

    Allendorf, F W; Gellman, W A; Thorgaard, G H

    1994-05-01

    We report the first sex-linked loci in Oncorhynchus mykiss (rainbow trout). Previous cytological and breeding experiments have demonstrated an XX/XY sex determining system in this and other salmonid species. Joint segregation data from fathers indicated an average of 8.1 per cent recombination between HEX-2 and the sex determining locus (SEX). The average recombination between HEX-2 and sSOD-1 in fathers was 26.8 per cent. No evidence of non-random segregation of HEX-2 and sSOD-1 was found in mothers; this difference in recombination rates between males and females is concordant with previous studies with rainbow trout and other salmonid species. These results also suggest the possibility that proper chromosomal pairing and segregation in salmonid males does not require a crossover event. Unlike the extreme XX/XY heteromorphy in mammals, functional alleles for HEX-2 and sSOD-1 occur on both the X and Y chromosomes. Significant non-random associations (i.e. gametic disequilibrium) occur between genotypes at HEX-2 and SEX in the hatchery population used for the inheritance study. This gametic disequilibrium has resulted in large changes in allele frequency at HEX-2 from one generation to the next and an excess of heterozygotes in comparison to expected binomial (i.e. Hardy-Weinberg) proportions.

  6. Sex recombination, and reproductive fitness: an experimental study using Paramecium

    Energy Technology Data Exchange (ETDEWEB)

    Nyberg, D.

    1982-08-01

    The effect of sex and recombination on reproductive fitness are measured using five wild stocks of Paramecium primaurelia. Among the wild stocks there were highly significant differences in growth rates. No hybrid had as low a fitness as the least fit parental stock. Recombination produced genotypes of higher fitness than those of either parent only in the cross between the two stocks of lowest fitness. The increase in variance of fitness as a result of recombination was almost exclusively attributable to the generation lines with low fitness. The fitness consequences of sexuality and mate choice were stock specific; some individuals leaving the most descendants by inbreeding, others by outcrossing. For most crosses the short-term advantage of sex, if any, accrue from the fusion of different gametes (hybrid vigor) and not from recombination. Since the homozygous genotype with the highest fitnes left the most progeny by inbreeding (no recombination), the persistence of conjugation in P. primaurelia is paradoxical. (JMT)

  7. Oral sex.

    Science.gov (United States)

    1996-04-05

    The Gay and Lesbian Medical Association urges HIV prevention specialists to regard male-to-male oral-genital sex as a low-risk activity and concentrate instead on the danger of unprotected anal intercourse. According to the association, the confusion and mixed messages surrounding oral sex are harming efforts to encourage gay men to make rational choices about truly risky behavior. The recommendations appear in the association's position paper issued March 19, 1996.

  8. Why Sex?

    DEFF Research Database (Denmark)

    Nielsen, Rasmus

    2006-01-01

    It is assumed that most organisms have sex because the resulting genetic recombination allows Darwinian selection to work better. It is now shown that in water fleas, recombination does lead to fewer deleterious mutations.......It is assumed that most organisms have sex because the resulting genetic recombination allows Darwinian selection to work better. It is now shown that in water fleas, recombination does lead to fewer deleterious mutations....

  9. Occurrence of 2n gametes in the F1 hybrids of Oriental x Asiatic lilies (Lilium): Relevance to intergenomic recombination and backcrossing

    NARCIS (Netherlands)

    Barba Gonzalez, R.; Lim, K.B.; Ramanna, M.S.; Visser, R.G.F.; Tuyl, van J.M.

    2005-01-01

    Cytological modes of the origin of 2n gametes were investigated in six different genotypes of F1 hybrids between Oriental and Asiatic (OA) lilies (Lilium, 2n = 2x = 24). Chromosome pairing between the parental genomes was very low, the average frequency range from 0.3 to 1.2 bivalents per cell among

  10. Influence of gametal release method and larval initial density in the culture of the sea urchin Paracentrotus lividus

    Directory of Open Access Journals (Sweden)

    Sílvia C. Gonçalves

    2014-06-01

    Full Text Available The gonads of sea urchins have increased interest for human consumption, as a culinary delicacy worldwide. In Europe, the species Paracentrotus lividus was identified as an ideal candidate to meet the growing demand for this product, due to its high gonadosomatic index and easy access. However, the current commercial model, based on the exploitation its natural populations, may be unsustainable. Therefore, its production in aquaculture would be beneficial to avoid depletion of natural stocks of these organisms. The present study sought to develop a culture system for Paracentrotus lividus in aquaculture, which would allow maintaining the early embryonic and larval stages of this animal. A trial was set using 3 gametal release methods (due to stress induced by capture and by injecting 0.125M and 0.250M of potassium chloride and 3 densities of sea urchin embryos (530 embryos/L, 1000 embryos/L and 2000 embryos/L, using 5 replicate individual culture tanks for each combined factor. The embryos were obtained by adding gametes to sea water, in a proportion 1 egg : 100 spermatozoids, and by discarding unfertilized floating eggs by decantation. Afterwards, the embryos were transferred to a culture system composed by cylindrical-conical plastic tanks of 2L. These were decontaminated and filled with 0.750L of sea water, continuously aerated through a sterile pipette of 3mL. These tanks were placed on metal shelves, artificially illuminated with daylight fluorescent lamps (18w/765, 400Lux and maintained at 22°C. The larvae were fed each 2 days, with a mixture of microalgae Tetraselmis chuii, Phaeodactylum tricornumtum and Thalassiosira weliflogii at a concentration of 800-1000 microalgae/mL, adding 15µL, 50µL and 30µL to each individual tank, respectively for each of the initial larval densities introduced. There was an influence of the factor initial larval density in the mortality rate, wherein the number of larvae that died during the trial was much

  11. First llama (Lama glama) pregnancy obtained after in vitro fertilization and in vitro culture of gametes from live animals.

    Science.gov (United States)

    Trasorras, V; Baca Castex, C; Alonso, A; Giuliano, S; Santa Cruz, R; Arraztoa, C; Chaves, G; Rodríguez, D; Neild, D; Miragaya, M

    2014-07-01

    The aim of this study was to evaluate the developmental competence and pregnancy rate of llama hatched blastocysts produced in vitro using gametes from live animals and two different culture conditions. Fifteen adult females were superstimulated with 1500 IU of eCG, eleven (73%) responded to the treatment and were used as oocyte donors. Follicular aspiration was conducted by flank laparotomy. Semen collections were performed under general anesthesia by electroejaculation of the male. Sixty-six COCs were recovered from 77 aspirated follicles (86% recovery) and were randomly placed in Fertil-TALP microdroplets with the sperm suspension (20 × 10(6)live spermatozoa/ml). After 24 h, they were placed in SOFaa medium supplemented with FCS and randomly assigned to one of two culture conditions. Culture condition 1 (CC1) consisted of 6 days of culture (n=28) and culture condition 2 (CC2) consisted of renewing the culture medium every 48 h (n=35). In CC1, the blastocyst rate was 36% (10/28) and the hatched blastocyst rate was 28% (8/28) whereas in CC2, the blastocyst rate was 34% (12/35) and the hatched blastocyst rate was 20% (7/35) (p>0.05). No pregnancies were obtained after embryo transfer (ET) of CC1 blastocysts (0/8) while one pregnancy was obtained (1/7) after transferring a hatched blastocyst from CC2. Forty-two days after the ET, the pregnancy was lost. This study represents the first report of a pregnancy in the llama after intrauterine transfer of embryos produced by in vitro fertilization using gametes from live animals. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Effects of water pH on gamete activation, embryonic development, and larval normality in Prochilodus lineatus

    Directory of Open Access Journals (Sweden)

    Eduardo Antônio Sanches

    2015-08-01

    Full Text Available We investigated the effects of breeding water pH on the spermatic motility, artificial fertilization, and initial development of offspring in curimba, Prochilodus lineatus. After hormonal induction, we conducted gamete activation, artificial fertilization, and embryo incubation in water with pH values of 4.43 ± 0.13, 5.82 ± 0.14, 7.37 ± 0.10, 8.21 ± 0.06, and 9.57 ± 0.16. When the water pH was 6.65, spermatic motility was maintained for ?25.21 s (P < 0.05. The highest fertilization rates (P < 0.05 were obtained when the water pH ranged from 5.82 ± 0.14 to 8.21 ± 0.06, and the highest hatching rates (P < 0.05 were observed when the water pH was 7.37 ± 0.10. A water pH of between 7.37 ± 0.10 and 8.21 ± 0.06 resulted in more complete formation of the perivitelline space (P < 0.05; additionally, embryos incubated in alkaline waters produced a higher percentage of normal larvae (P < 0.05, despite increased mortality levels. Our results indicate that the pH of the water used for gamete activation, artificial oocyte fertilization, and incubation of eggs and larvae of P. lineatus should be ~7, in order to promote successful breeding and normal larval production.

  13. Assisted reproduction with gametes and embryos: what research is needed and fundable?

    Science.gov (United States)

    Seidel, George E

    2016-01-01

    Principles for selecting future research projects include interests of investigators, fundability, potential applications, ethical considerations, being able to formulate testable hypotheses and choosing the best models, including selection of the most appropriate species. The following 10 areas of assisted reproduction seem especially appropriate for further research: efficacious capacitation of bovine spermatozoa in vitro; improved in vitro bovine oocyte maturation; decreasing variability and increasing efficacy of bovine superovulation; improved fertility of sexed semen; improving equine IVF; improving cryopreservation of rooster spermatozoa; understanding differences between males in success of sperm cryopreservation and reasons for success in competitive fertilisation; mechanisms of reprogramming somatic cell nuclei after nuclear transfer; regulation of differentiation of ovarian primordial follicles; and means by which spermatozoa maintain fertility during storage in the epididymis. Issues are species specific for several of these topics, in most cases because the biology is species specific.

  14. Sex. Dev.

    OpenAIRE

    Jakubiczka, S.; Schröder, C.; Ullmann, R.; Volleth, M.; Ledig, S.; Gilberg, E.; Kroisel, P.; P. Wieacker, P.

    2010-01-01

    Campomelic dysplasia (MIM 114290) is a severe malformation syndrome frequently accompanied by male-to-female sex reversal. Causative are mutations within the SOX9 gene on 17q24.3 as well as chromosomal aberrations (translocations, inversions or deletions) in the vicinity of SOX9 . Here, we report on a patient with muscular hypotonia, craniofacial dysmorphism, cleft palate, brachydactyly, malformations of thoracic spine, and gonadal dysgenesis with female external genitalia and müllerian duct ...

  15. Linkage analysis for the gametic lethal gene of a rice variety 'Koshihikari' and the semi-dwarfing gene induced in 'Koshihikari'

    International Nuclear Information System (INIS)

    Tomita, M.; Tanisaka, T.; Okumoto, Y.; Yamagata, H.

    1990-01-01

    Full text: 'Koshihikari', a Japanese tall variety, is now most widely cultivated in Japan because of its good quality and taste, but is extremely poor in lodging resistance. In order to create a semi-dwarf 'Koshihikari', large scale mutation breeding was carried out at Hokuriku Agricultural Experiment Station, resulting in the production of an excellent semi-dwarf mutant strain 'Hokuriku 100'. It has extensively been used as cross parent. Genetic analyses revealed that the semi-dwarfness of 'Hokuriku 100' is controlled by two mutant genes, a recessive semi-dwarfness gene sd(t) and a non-gametic lethal gene lt m mutated from the genetic lethal gene of 'Koshihikari' lt, which would cause abortion of both male and female gametes when it occurs together with sd(t). Further analyses led to conclude that It is located on chromosome 9, sd(t) on chromosome 10. (author)

  16. How parents whose children have been conceived with donor gametes make their disclosure decision: contexts, influences, and couple dynamics.

    Science.gov (United States)

    Shehab, Dena; Duff, Julia; Pasch, Lauri A; Mac Dougall, Kirstin; Scheib, Joanna E; Nachtigall, Robert D

    2008-01-01

    To describe parents' disclosure decision-making process. In-depth ethnographic interviews. Participants were recruited from 11 medical infertility practices and 1 sperm bank in Northern California. One hundred forty-one married couples who had conceived a child using donor gametes (62 with donor sperm, 79 with donor oocytes). Husbands and wives were interviewed together and separately. Thematic analysis of interview transcripts. Ninety-five percent of couples came to a united disclosure decision, some "intuitively," but most after discussions influenced by the couples' local sociopolitical environment, professional opinion, counseling, religious and cultural background, family relationships, and individual personal, psychological, and ethical beliefs. Couples who were not initially in agreement ultimately came to a decision after one partner deferred to the wishes or opinions of the other. Deferral could reflect the result of a prior agreement, one partner's recognition of the other's experiential or emotional expertise, or direct persuasion. In disclosing couples, men frequently deferred to their wives, whereas, in nondisclosing couples, women always deferred to their husbands. Although the majority of couples were in initial agreement about disclosure, for many the disclosure decision was a complex, negotiated process reflecting a wide range of influences and contexts.

  17. Restoration of critically endangered elkhorn coral (Acropora palmata populations using larvae reared from wild-caught gametes

    Directory of Open Access Journals (Sweden)

    Valérie F. Chamberland

    2015-07-01

    Full Text Available Elkhorn coral (Acropora palmata populations provide important ecological functions on shallow Caribbean reefs, many of which were lost when a disease reduced their abundance by more than 95% beginning in the mid-1970s. Since then, a lack of significant recovery has prompted rehabilitation initiatives throughout the Caribbean. Here, we report the first successful outplanting and long-term survival of A. palmata settlers reared from gametes collected in the field. A. palmata larvae were settled on clay substrates (substrate units and either outplanted on the reef two weeks after settlement or kept in a land-based nursery. After 2.5 years, the survival rate of A. palmata settlers outplanted two weeks after settlement was 6.8 times higher (3.4% than that of settlers kept in a land-based nursery (0.5%. Furthermore, 32% of the substrate units on the reef still harbored one or more well-developed recruit compared to 3% for substrate units kept in the nursery. In addition to increasing survival, outplanting A. palmata settlers shortly after settlement reduced the costs to produce at least one 2.5-year-old A. palmata individual from $325 to $13 USD. Thus, this study not only highlights the first successful long-term rearing of this critically endangered coral species, but also shows that early outplanting of sexually reared coral settlers can be more cost-effective than the traditional approach of nursery rearing for restoration efforts aimed at rehabilitating coral populations.

  18. Control of DEMETER DNA demethylase gene transcription in male and female gamete companion cells in Arabidopsis thaliana.

    Science.gov (United States)

    Park, Jin-Sup; Frost, Jennifer M; Park, Kyunghyuk; Ohr, Hyonhwa; Park, Guen Tae; Kim, Seohyun; Eom, Hyunjoo; Lee, Ilha; Brooks, Janie S; Fischer, Robert L; Choi, Yeonhee

    2017-02-21

    The DEMETER (DME) DNA glycosylase initiates active DNA demethylation via the base-excision repair pathway and is vital for reproduction in Arabidopsis thaliana DME-mediated DNA demethylation is preferentially targeted to small, AT-rich, and nucleosome-depleted euchromatic transposable elements, influencing expression of adjacent genes and leading to imprinting in the endosperm. In the female gametophyte, DME expression and subsequent genome-wide DNA demethylation are confined to the companion cell of the egg, the central cell. Here, we show that, in the male gametophyte, DME expression is limited to the companion cell of sperm, the vegetative cell, and to a narrow window of time: immediately after separation of the companion cell lineage from the germline. We define transcriptional regulatory elements of DME using reporter genes, showing that a small region, which surprisingly lies within the DME gene, controls its expression in male and female companion cells. DME expression from this minimal promoter is sufficient to rescue seed abortion and the aberrant DNA methylome associated with the null dme-2 mutation. Within this minimal promoter, we found short, conserved enhancer sequences necessary for the transcriptional activities of DME and combined predicted binding motifs with published transcription factor binding coordinates to produce a list of candidate upstream pathway members in the genetic circuitry controlling DNA demethylation in gamete companion cells. These data show how DNA demethylation is regulated to facilitate endosperm gene imprinting and potential transgenerational epigenetic regulation, without subjecting the germline to potentially deleterious transposable element demethylation.

  19. Regulation of meiotic entry and gonadal sex differentiation in the human

    DEFF Research Database (Denmark)

    Jørgensen, Anne; Rajpert-De Meyts, Ewa

    2014-01-01

    Meiosis is a unique type of cell division that is performed only by germ cells to form haploid gametes. The switch from mitosis to meiosis exhibits a distinct sex-specific difference in timing, with female germ cells entering meiosis during fetal development and male germ cells at puberty when...... spermatogenesis is initiated. During early fetal development, bipotential primordial germ cells migrate to the forming gonad where they remain sexually indifferent until the sex-specific differentiation of germ cells is initiated by cues from the somatic cells. This irreversible step in gonadal sex...... in the context of fetal gonad development and germ cell differentiation, with emphasis on results obtained in humans. Furthermore, the consequences of dysregulated meiosis signaling in humans are briefly discussed in the context of selected pathologies, including testicular germ cell cancer and some forms...

  20. When Sex Is Painful

    Science.gov (United States)

    ... AQ FREQUENTLY ASKED QUESTIONS GYNECOLOGIC PROBLEMS FAQ020 When Sex Is Painful • How common is painful sex? • What causes pain during sex? • Where is pain during sex felt? • When should ...

  1. Sex during Pregnancy

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Sex During Pregnancy KidsHealth / For Parents / Sex During Pregnancy ... satisfying and safe sexual relationship during pregnancy. Is Sex During Pregnancy Safe? Sex is considered safe during ...

  2. Chinmo prevents transformer alternative splicing to maintain male sex identity.

    Directory of Open Access Journals (Sweden)

    Lydia Grmai

    2018-02-01

    Full Text Available Reproduction in sexually dimorphic animals relies on successful gamete production, executed by the germline and aided by somatic support cells. Somatic sex identity in Drosophila is instructed by sex-specific isoforms of the DMRT1 ortholog Doublesex (Dsx. Female-specific expression of Sex-lethal (Sxl causes alternative splicing of transformer (tra to the female isoform traF. In turn, TraF alternatively splices dsx to the female isoform dsxF. Loss of the transcriptional repressor Chinmo in male somatic stem cells (CySCs of the testis causes them to "feminize", resembling female somatic stem cells in the ovary. This somatic sex transformation causes a collapse of germline differentiation and male infertility. We demonstrate this feminization occurs by transcriptional and post-transcriptional regulation of traF. We find that chinmo-deficient CySCs upregulate tra mRNA as well as transcripts encoding tra-splice factors Virilizer (Vir and Female lethal (2d (Fl(2d. traF splicing in chinmo-deficient CySCs leads to the production of DsxF at the expense of the male isoform DsxM, and both TraF and DsxF are required for CySC sex transformation. Surprisingly, CySC feminization upon loss of chinmo does not require Sxl but does require Vir and Fl(2d. Consistent with this, we show that both Vir and Fl(2d are required for tra alternative splicing in the female somatic gonad. Our work reveals the need for transcriptional regulation of tra in adult male stem cells and highlights a previously unobserved Sxl-independent mechanism of traF production in vivo. In sum, transcriptional control of the sex determination hierarchy by Chinmo is critical for sex maintenance in sexually dimorphic tissues and is vital in the preservation of fertility.

  3. Chinmo prevents transformer alternative splicing to maintain male sex identity.

    Science.gov (United States)

    Grmai, Lydia; Hudry, Bruno; Miguel-Aliaga, Irene; Bach, Erika A

    2018-02-01

    Reproduction in sexually dimorphic animals relies on successful gamete production, executed by the germline and aided by somatic support cells. Somatic sex identity in Drosophila is instructed by sex-specific isoforms of the DMRT1 ortholog Doublesex (Dsx). Female-specific expression of Sex-lethal (Sxl) causes alternative splicing of transformer (tra) to the female isoform traF. In turn, TraF alternatively splices dsx to the female isoform dsxF. Loss of the transcriptional repressor Chinmo in male somatic stem cells (CySCs) of the testis causes them to "feminize", resembling female somatic stem cells in the ovary. This somatic sex transformation causes a collapse of germline differentiation and male infertility. We demonstrate this feminization occurs by transcriptional and post-transcriptional regulation of traF. We find that chinmo-deficient CySCs upregulate tra mRNA as well as transcripts encoding tra-splice factors Virilizer (Vir) and Female lethal (2)d (Fl(2)d). traF splicing in chinmo-deficient CySCs leads to the production of DsxF at the expense of the male isoform DsxM, and both TraF and DsxF are required for CySC sex transformation. Surprisingly, CySC feminization upon loss of chinmo does not require Sxl but does require Vir and Fl(2)d. Consistent with this, we show that both Vir and Fl(2)d are required for tra alternative splicing in the female somatic gonad. Our work reveals the need for transcriptional regulation of tra in adult male stem cells and highlights a previously unobserved Sxl-independent mechanism of traF production in vivo. In sum, transcriptional control of the sex determination hierarchy by Chinmo is critical for sex maintenance in sexually dimorphic tissues and is vital in the preservation of fertility.

  4. Sex Education

    Directory of Open Access Journals (Sweden)

    R N Srivastava

    1994-06-01

    Full Text Available Sex, though not everything in life, is a profoundly important aspect of human existence. It has evolved to serve more than reproductive functions; relational and recreational functions having taken precedence over procrea­tional. Sex has come to play a much wider socio-psychological function. Human sexuality is complex and multidimensional. It is subject to influence by multitude of factors often grouped as biological (e.g. genes, hormones, psychological (e.g. fear, anxiety, mood and socio-cultural (e.g. sex roles, values- religious/moral/ethical, customs. It is the interaction and interrelationship of these factors from the time of conception, through intrauterine life, infancy, childhood and adolescence, till adulthood (even later in life that determine the sexual development expressed as sexual attitudes and behaviour of the people. Learning, both social and cognitive, plays a significantly important role in such development. Sexual dysfunctions in men and women, result from factors often categorised as physical or organic and psychological; more often a combination may be involved. Experience has shown that in majority of men and women in India having sexual problems, ignorance misconceptions and prevailing myths are invariably responsible in the causation of Ihese problems. Sexual problems in individual man (e.g. erectile failure and woman (e.g. vaginismus cause anxiety, feelings of frustration, lowered self esteem and symptoms of depression. The condition may also affect the spouse; he/she, as a reaction to the problem in the partner, may develop sexual and psychosocial problems including distressed marital relationship. This may also have influence on general couple relationship, effecting adversely the quality of family life. Modern therapeutic endevours have made it possible now to offer effective therapy to most people who seek help for their sexual problems, thus preventing the consequences on couple relationship. However, there is

  5. SEX EDUCATION

    Directory of Open Access Journals (Sweden)

    R N Srivastava

    1994-06-01

    Full Text Available Sex, though not everything in life, is a profoundly important aspect of human existence. It has evolved to serve more than reproductive functions; relational and recreational functions having taken precedence over procrea­tional. Sex has come to play a much wider socio-psychological function.Human sexuality is complex and multidimensional. It is subject to influence by multitude of factors often grouped as biological (e.g. genes, hormones, psychological (e.g. fear, anxiety, mood and socio-cultural (e.g. sex roles, values- religious/moral/ethical, customs. It is the interaction and interrelationship of these factors from the time of conception, through intrauterine life, infancy, childhood and adolescence, till adulthood (even later in life that determine the sexual development expressed as sexual attitudes and behaviour of the people. Learning, both social and cognitive, plays a significantly important role in such development.Sexual dysfunctions in men and women, result from factors often categorised as physical or organic and psychological; more often a combination may be involved. Experience has shown that in majority of men and women in India having sexual problems, ignorance misconceptions and prevailing myths are invariably responsible in the causation of Ihese problems. Sexual problems in individual man (e.g. erectile failure and woman (e.g. vaginismus cause anxiety, feelings of frustration, lowered self esteem and symptoms of depression. The condition may also affect the spouse; he/she, as a reaction to the problem in the partner, may develop sexual and psychosocial problems including distressed marital relationship. This may also have influence on general couple relationship, effecting adversely the quality of family life.Modern therapeutic endevours have made it possible now to offer effective therapy to most people who seek help for their sexual problems, thus preventing the consequences on couple relationship. However, there is also

  6. The specification and global reprogramming of histone epigenetic marks during gamete formation and early embryo development in C. elegans.

    Directory of Open Access Journals (Sweden)

    Mark Samson

    2014-10-01

    Full Text Available In addition to the DNA contributed by sperm and oocytes, embryos receive parent-specific epigenetic information that can include histone variants, histone post-translational modifications (PTMs, and DNA methylation. However, a global view of how such marks are erased or retained during gamete formation and reprogrammed after fertilization is lacking. To focus on features conveyed by histones, we conducted a large-scale proteomic identification of histone variants and PTMs in sperm and mixed-stage embryo chromatin from C. elegans, a species that lacks conserved DNA methylation pathways. The fate of these histone marks was then tracked using immunostaining. Proteomic analysis found that sperm harbor ∼2.4 fold lower levels of histone PTMs than embryos and revealed differences in classes of PTMs between sperm and embryos. Sperm chromatin repackaging involves the incorporation of the sperm-specific histone H2A variant HTAS-1, a widespread erasure of histone acetylation, and the retention of histone methylation at sites that mark the transcriptional history of chromatin domains during spermatogenesis. After fertilization, we show HTAS-1 and 6 histone PTM marks distinguish sperm and oocyte chromatin in the new embryo and characterize distinct paternal and maternal histone remodeling events during the oocyte-to-embryo transition. These include the exchange of histone H2A that is marked by ubiquitination, retention of HTAS-1, removal of the H2A variant HTZ-1, and differential reprogramming of histone PTMs. This work identifies novel and conserved features of paternal chromatin that are specified during spermatogenesis and processed in the embryo. Furthermore, our results show that different species, even those with diverged DNA packaging and imprinting strategies, use conserved histone modification and removal mechanisms to reprogram epigenetic information.

  7. 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.

  8. 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.

  9. Multiple and asymmetrical origin of polyploid dog rose hybrids (Rosa L. sect. Caninae (DC.) Ser.) involving unreduced gametes.

    Science.gov (United States)

    Herklotz, V; Ritz, C M

    2017-08-01

    Polyploidy and hybridization are important factors for generating diversity in plants. The species-rich dog roses ( Rosa sect. Caninae ) originated by allopolyploidy and are characterized by unbalanced meiosis producing polyploid egg cells (usually 4 x ) and haploid sperm cells (1 x ). In extant natural stands species hybridize spontaneously, but the extent of natural hybridization is unknown. The aim of the study was to document the frequency of reciprocal hybridization between the subsections Rubigineae and Caninae with special reference to the contribution of unreduced egg cells (5 x ) producing 6 x offspring after fertilization with reduced (1 x ) sperm cells. We tested whether hybrids arose by independent multiple events or via a single or few incidences followed by a subsequent spread of hybrids. Population genetics of 45 mixed stands of dog roses across central and south-eastern Europe were analysed using microsatellite markers and flow cytometry. Hybrids were recognized by the presence of diagnostic alleles and multivariate statistics were used to display the relationships between parental species and hybrids. Among plants classified to subsect. Rubigineae , 32 % hybridogenic individuals were detected but only 8 % hybrids were found in plants assigned to subsect. Caninae . This bias between reciprocal crossings was accompanied by a higher ploidy level in Rubigineae hybrids, which originated more frequently by unreduced egg cells. Genetic patterns of hybrids were strongly geographically structured, supporting their independent origin. The biased crossing barriers between subsections are explained by the facilitated production of unreduced gametes in subsect. Rubigineae . Unreduced egg cells probably provide the highly homologous chromosome sets required for correct chromosome pairing in hybrids. Furthermore, the higher frequency of Rubigineae hybrids is probably influenced by abundance effects because the plants of subsect. Caninae are much more abundant

  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. Multiple sex partner

    African Journals Online (AJOL)

    User

    intercourse, about 60% reported having a single sexual partner and 40% reported having multiple ... masturbation, start having sex at a younger age, have sex with married people and/or .... sex were considered unacceptable by 89 vs.

  12. 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.

  13. The gametic synapse

    DEFF Research Database (Denmark)

    Macaulay, Angus D.; Gilbert, Isabelle; Caballero, Julieta

    2014-01-01

    Even after several decades of quiescent storage in the ovary, the female germ cell is capable of reinitiating transcription to build the reserves that are essential to support early embryonic development. In the current model of mammalian oogenesis, there exists bilateral communication between th...

  14. Understanding Sex for Sale

    DEFF Research Database (Denmark)

    This book Understanding Sex for Sale: Meanings and Moralities of Sexual Commerce is dedicated to the exploration of the ways in which sex prostitution, sex work or sex for sale are taken for granted by particularly looking at how the relation between sex and money is interpreted and enacted....... This interdisciplinary book aims to understand how prostitution, sex work or sex for sale are defined, delineated, contested and understood in different places and times. The book offers contributions from a number of scholars who, based on their on their own research, discuss on going theoretical issues and analytical...... challenges Some chapters focuses on how prostitution, sex work or sex for sale have been regulated by the authorities and what understandings this regulation builds on. Other chapters investigate the experiences of the sex workers and sex buyers asking how these actors adjust to or resist the categorisation...

  15. Only two sex forms but multiple gender variants: How to explain?

    Science.gov (United States)

    De Loof, Arnold

    2018-01-01

    ABSTRACT Are sex and gender interchangeable terms? In classical biology, both are sometimes but not always used on an equal basis for some groups of animals. However, for our own species the Homo sapiens, they are not. A major question is why are there only two types of gametes (sperm- and egg cells), two types of sex steroids, (androgens and estrogens in vertebrates, and two types of ecdysteroids in insects), while the reproduction-related behaviour of the gamete producers displays a much greater variability than just two prominent forms, namely heterosexual males and heterosexual females? It indicates that in addition to a few sex-determining genes ( = the first pillar), other factors play a role. A second possible pillar is the still poorly understood cognitive memory system in which electrical phenomena and its association with the plasma membrane membrane-cytoskeletal complex of cells play a major role (learning, imitation and imprinting). This paper advances a third pillar, that hitherto has been almost completely ignored, namely the cellular Ca2+-homeostasis system, more specifically its sex-specific differences. Differential male-female genetics- and hormone-based Ca2+-homeostasis with effects on gender-related processes has been named Calcigender before. It will be argued that it follows from the principles of Ca2+- physiology and homeostasis that all individuals of a sexually reproducing animal population have a personalized gender behaviour. Thus, subdividing gender-behaviours in hetero-, homo-, bi-, trans- etc. which all result from a differential use of the very same basic physiological principles, is too primitive a system that may yield false sociological interpretations. PMID:29497472

  16. Assigning sex and reproductive stage to adult Lake Sturgeon using ultrasonography and common morphological measurements

    Science.gov (United States)

    Chiotti, Justin A.; Boase, James C.; Hondorp, Darryl W.; Briggs, Andrew S.

    2016-01-01

    Sex determination of fish species is difficult to assess when sexual dimorphism and gametes are not apparent. For threatened and endangered fish species, noninvasive techniques are needed when determining sex to minimize stress and the potential for mortality. We evaluated the use of a portable ultrasound unit to determine sex of Lake Sturgeon Acipenser fulvescens in the field. Ultrasound images were collected from 9 yellow-egg (F2, F3), 32 black-egg (F4, F5), and 107 fully developed male (M2) Lake Sturgeon. Two readers accurately assigned sex to 88–96% of fish, but accuracy varied in relation to maturity stage. Black-egg females and fully developed males were correctly identified for 89–100% of the fish sampled, while these two readers identified yellow-egg females only 33% and 67% of the time. Time spent collecting images ranged between 2 and 3 min once the user was comfortable with operating procedures. Discriminant analysis revealed the total length : girth ratio was a strong predictor of sex and maturity, correctly classifying 81% of black-egg females and 97% of the fully developed males. However, yellow-egg females were incorrectly classified on all occasions. This study shows the utility of using ultrasonography and a total length : girth ratio for sex determination of Lake Sturgeon in later reproductive stages around the spawning season.

  17. Expression and putative function of fibronectin and its receptor (integrin alpha(5)beta(1)) in male and female gametes during bovine fertilization in vitro.

    Science.gov (United States)

    Thys, Mirjan; Nauwynck, Hans; Maes, Dominiek; Hoogewijs, Maarten; Vercauteren, Dries; Rijsselaere, Tom; Favoreel, Herman; Van Soom, Ann

    2009-09-01

    Fibronectin (Fn) is a 440 kDa glycoprotein assumed to participate in sperm-egg interaction in human. Recently, it has been demonstrated that Fn--when present during bovine IVF--strongly inhibits sperm penetration. The present study was conducted firstly to evaluate the expression of Fn and its integrin receptor (alpha(5)beta(1)) on male and female bovine gametes using indirect immunofluorescence and secondly, to determine the function of Fn during bovine IVF. Endogenous Fn was detected underneath the zona pellucida (ZP) and integrin alpha(5) on the oolemma of cumulus-denuded oocytes. Bovine spermatozoa displayed integrin alpha(5) at their equatorial segment after acrosome reaction. We established that the main inhibitory effect of exogenously supplemented Fn was located at the sperm-oolemma binding, with a (concurrent) effect on fusion, and this can probably be attributed to the binding of Fn to spermatozoa at the equatorial segment, as shown by means of Alexa Fluor 488-conjugated Fn. Combining these results, the inhibitory effect of exogenously supplemented Fn seemed to be exerted on the male gamete by binding to the exposed integrin alpha(5)beta(1) receptor after acrosome reaction. The presence of endogenous Fn underneath the ZP together with integrin alpha(5) expression on oolemma and acrosome-reacted (AR) sperm cell surface suggests a 'velcro' interaction between the endogenous Fn ligand and corresponding receptors on both (AR) sperm cell and oolemma, initiating sperm-egg binding.

  18. Coevolution of parental investment and sexually selected traits drives sex-role divergence.

    Science.gov (United States)

    Fromhage, Lutz; Jennions, Michael D

    2016-08-18

    Sex-role evolution theory attempts to explain the origin and direction of male-female differences. A fundamental question is why anisogamy, the difference in gamete size that defines the sexes, has repeatedly led to large differences in subsequent parental care. Here we construct models to confirm predictions that individuals benefit less from caring when they face stronger sexual selection and/or lower certainty of parentage. However, we overturn the widely cited claim that a negative feedback between the operational sex ratio and the opportunity cost of care selects for egalitarian sex roles. We further argue that our model does not predict any effect of the adult sex ratio (ASR) that is independent of the source of ASR variation. Finally, to increase realism and unify earlier models, we allow for coevolution between parental investment and investment in sexually selected traits. Our model confirms that small initial differences in parental investment tend to increase due to positive evolutionary feedback, formally supporting long-standing, but unsubstantiated, verbal arguments.

  19. Impaired gamete production and viability in Atlantic croaker collected throughout the 20,000 km(2) hypoxic region in the northern Gulf of Mexico.

    Science.gov (United States)

    Thomas, Peter; Rahman, Md Saydur; Picha, Matthew E; Tan, Wenxian

    2015-12-15

    The long-term impacts of recent marked increases in the incidence and extent of hypoxia (dissolved oxygen Gulf of Mexico. Potential fecundity was significantly lower in croaker collected throughout the ~20,000 km(2) hypoxic region than in croaker from normoxic sites. In vitro bioassays of gamete viability showed reductions in oocyte maturation and sperm motility in croaker collected from the hypoxic sites in response to reproductive hormones which were accompanied by decreases in gonadal levels of membrane progestin receptor alpha, the receptor regulating these processes. The finding that environmental hypoxia exposure reduces oocyte viability in addition to decreasing oocyte production in croaker suggests that fecundity estimates need to be adjusted to account for the decrease in oocyte maturation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Influence of spawning procedure on gametes fertilization success in Salminus hilarii Valenciennes, 1850 (Teleostei: Characidae: Implications for the conservation of this species

    Directory of Open Access Journals (Sweden)

    Renato M. Honji

    Full Text Available Artificial reproduction and gamete fertilization were evaluated in Salminus hilarii wild and domesticated broodstocks. Wild and domesticated broodstocks were artificially induced to reproduction using a carp pituitary treatment. Four groups were considered: Group 1 (G1, fish caught in the wild maintained for three years in the same conditions as the domesticated broodstocks and spawned naturally; Group 2 (G2, broodstock born and raised in captivity and spawned naturally; Group 3 (G3, wild broodstocks, which were manually stripped for gamete collection and dry fertilization; and Group 4 (G4, domesticated males and females, also manually stripped. Oocytes, eggs, and larvae were sampled at different time intervals throughout embryonic development. Yolk sac absorption occurred approximately 24-29 h after hatching. Twenty-six h after hatching, the larvae mouths opened. Cannibalism was identified just 28-30 h after hatching. There was no morphological difference in embryonic development among all groups. The number of released eggs per gram of female was: G1: 83.3 ± 24.5 and G2: 103.8 ± 37.4; however, the fertilization success was lower in G2 (42.0 ± 6.37 % compared with G1 (54.7 ± 3.02% (P = 0.011. Hand-stripping of oocytes was not successful and the fertilization rate was zero. The reproduction of this species in captivity is viable, but it is necessary to improve broodstock management to enhance fertilization rates and obtain better fingerling production for restocking programs.

  1. Radiation mutagenesis and modifying thereof by visible light in c3G male gamets of Drosophilla melanogaster

    International Nuclear Information System (INIS)

    Aleksandrov, I.D.

    1979-01-01

    A study was made of photoreactivation of γ-ray-induced genetic damages in postmeiotic male germ cells of c3G mutant of Drosophila melanogaster. Room light was found to decrease (DRF 1.5-2.2) the frequency of both the chromosomal mutations at five selected loci and large deletions of the X-chromosome. This effect of visible light is similar to that produced on the survival rate of γ-irradiated E. coli cells. On the other hand, exposure to light leads to a significant increase in the yield of both the point visible mutations and recessive sex-linked lethals as compared to that obtained in the dark

  2. Sex Education: Another View

    Science.gov (United States)

    Hamilton, Jennifer

    1977-01-01

    The mother of a 14-year-old mentally retarded boy comments on the viewpoints of Dr. Sol Gordon (a sex education columnist) regarding masturbation, questions on sex, marriage, and the parents' role. (SBH)

  3. Epigenetic battle of the sexes. Comment on: ;Epigenetic game theory: How to compute the epigenetic control of maternal-to-zygotic transition; by Qian Wang et al.

    Science.gov (United States)

    Wu, Song

    2017-03-01

    Qian Wang et al. present an interesting framework, named epigenetic game theory, for modeling sex-based epigenetic dynamics during embryogenesis from a new viewpoint of evolutionary game theory [1]. That is, epigenomes of sperms and oocytes may coordinate through either cooperation or competition, or both, to affect the fitness of embryos. The work uses a set of ordinary differential equations (ODEs) to describe longitudinal trajectories of DNA methylation levels in both parental and maternal gametes and their dependence on each other. The insights gained from this review, i.e. dynamic methylation profiles and their interaction are potentially important to many fields, such as biomedicine and agriculture.

  4. Sex in situ

    DEFF Research Database (Denmark)

    Krøgholt, Ida

    2017-01-01

    Sex er en del af vores sociale praksis og centralt for det, vi hver især er. Men bortset fra pornoindustrien, har vi ikke mange muligheder for at få adgang til billeder af sex. Teater Nordkrafts forestilling Sex in situ vil gøre seksuelle billeder til noget, der kan deles, udveksles og tales om, og...

  5. Coeducation and Sex Roles.

    Science.gov (United States)

    Harris, Mary B.

    1986-01-01

    A study of the sex role stereotypes held by 538 first-term Australian university students from single-sex and coeducational high schools is presented. Results suggest that coeducational schooling may have some advantages for fostering interactions with the opposite sex. (MSE)

  6. sex and Cannibalism

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 12. The Secret Sex Lives of Rotifers Sex - sex and Cannibalism. T Ramakrishna Rao. General Article Volume 5 Issue 12 December 2000 pp 41-47. Fulltext. Click here to view fulltext PDF. Permanent link:

  7. A Sex Work Research Symposium: Examining Positionality in Documenting Sex Work and Sex Workers’ Rights

    OpenAIRE

    Megan Lowthers; Magdalena Sabat; Elya M. Durisin; Kamala Kempadoo

    2017-01-01

    Historically, academic literature on sex work has documented the changing debates, policies, and cultural discourse surrounding the sex industry, and their impact on the rights of sex workers worldwide. As sex work scholars look to the future of sex workers’ rights, however, we are also in a critical moment of self-reflection on how sex work scholarship engages with sex worker communities, produces knowledge surrounding sex work, and represents the lived experiences of sex workers’ rights, or...

  8. Neuroprotection of Sex Steroids

    Science.gov (United States)

    Liu, Mingyue; Kelley, Melissa H.; Herson, Paco S.; Hurn, Patricia D.

    2011-01-01

    Sex steroids are essential for reproduction and development in animals and humans, and sex steroids also play an important role in neuroprotection following brain injury. New data indicate that sex-specific responses to brain injury occur at the cellular and molecular levels. This review summarizes the current understanding of neuroprotection by sex steroids, particularly estrogen, androgen, and progesterone, based on both in vitro and in vivo studies. Better understanding of the role of sex steroids under physiological and pathological conditions will help us to develop novel effective therapeutic strategies for brain injury. PMID:20595940

  9. 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.

  10. Sexing young snowy owls

    Science.gov (United States)

    Seidensticker, M.T.; Holt, D.W.; Detienne, J.; Talbot, S.; Gray, K.

    2011-01-01

    We predicted sex of 140 Snowy Owl (Bubo scandiacus) nestlings out of 34 nests at our Barrow, Alaska, study area to develop a technique for sexing these owls in the field. We primarily sexed young, flightless owls (3844 d old) by quantifying plumage markings on the remiges and tail, predicting sex, and collecting blood samples to test our field predictions using molecular sexing techniques. We categorized and quantified three different plumage markings: two types of bars (defined as markings that touch the rachis) and spots (defined as markings that do not touch the rachis). We predicted sex in the field assuming that males had more spots than bars and females more bars than spots on the remiges and rectrices. Molecular data indicated that we correctly sexed 100% of the nestlings. We modeled the data using random forests and classification trees. Both models indicated that the number and type of markings on the secondary feathers were the most important in classifying nestling sex. The statistical models verified our initial qualitative prediction that males have more spots than bars and females more bars than spots on flight feathers P6P10 for both wings and tail feathers T1 and T2. This study provides researchers with an easily replicable and highly accurate method for sexing young Snowy Owls in the field, which should aid further studies of sex-ratios and sex-related variation in behavior and growth of this circumpolar owl species. ?? 2011 The Raptor Research Foundation, Inc.

  11. Osho - Insights on sex.

    Science.gov (United States)

    Nagaraj, Anil Kumar Mysore

    2013-01-01

    Sex is a mysterious phenomenon, which has puzzled even great sages. Human beings have researched and mastered the biology of sex. But that is not all. Sex needs to be understood from the spiritual perspective too. The vision of Osho is an enlightening experience in this regard. Out of the thousands of lectures, five lectures on sex made Osho most notorious. Born into a Jain family of Madhya Pradesh, Rajneesh, who later wanted himself to be called Osho, is a great master. He has spoken volumes on a wide range of topics ranging from sex to super-consciousness. His contributions in the area of sex are based on the principles of "Tantra" which has its origin from Buddhism. This article focuses on his life and insights on sex, which if understood properly, can be a stepping stone for enlightenment.

  12. Helping Behavior: Effects of Sex and Sex-Typing.

    Science.gov (United States)

    Basow, Susan A.; Crawley, Donna M.

    1982-01-01

    Male and female experimenters requested adult shoppers (N=178) to fill out a questionnaire. Refusal data showed shoppers helping other-sex more than same-sex experimenters. Other results showed a significant three-way interaction among helper and helpee sex and sex-typing and situation sex-typing and that helper sex-typing did not have significant…

  13. Doing gender in sex and sex research.

    Science.gov (United States)

    Vanwesenbeeck, Ine

    2009-12-01

    Gender is central to sexuality, and vice versa, but there are a number of difficulties with the treatment of gender in sex research. Apparently, it is hard to find a balance between two conflicting needs. First, obviously, it is necessary to make distinctions between women and men, for political as well as research-technical and theoretical reasons. A second requirement, at odds with the first one, is the necessity to understand gender and its relation to sexuality and the body as much more complex than simplistically referring to two sets of individuals. This is all the more necessary when one realizes the possible drawbacks of exaggerating the differences between the sexes (in particular when they are biologically explained), because of stereotyping, stigmatizing, and expectancy confirmatory processes. This essay identifies and discusses 10 difficulties in the treatment of gender in sex research, reflects on their origins, and reviews theory and evidence with the aim to (1) consider the relative strength of gender/sex as an explanatory variable compared to other factors and processes explaining differences between men and women on a number of sexual aspects, (2) inform an understanding of gender and its relation to sexuality as an ongoing, open-ended, multi-determined, situated, interactional process, with the body as a third player, and (3) argue in favor of a nuanced, well-balanced treatment of gender in sex research.

  14. Sex reversal in vertebrates

    OpenAIRE

    2016-01-01

    This special topic issue of Sexual Development gives an overview of sex reversal in vertebrates, from fishes naturally changing their sex, to rodents escaping the mammalian SRY-determining system. It offers eight up-to-date reviews on specific subjects in sex reversal, considering fishes, amphibians, reptiles, birds, marsupials, and placental mammals, including humans. The broad scope of represented animals makes this ideal for students and researchers, especially those interested in the...

  15. Environmental concentrations of irgarol, diuron and S-metolachlor induce deleterious effects on gametes and embryos of the Pacific oyster, Crassostrea gigas.

    Science.gov (United States)

    Mai, Huong; Morin, Bénédicte; Pardon, Patrick; Gonzalez, Patrice; Budzinski, Hélène; Cachot, Jérôme

    2013-08-01

    Irgarol and diuron are the most representative "organic booster biocides" that replace organotin compounds in antifouling paints, and metolachlor is one of the most extensively used chloroacetamide herbicides in agriculture. The toxicity of S-metolachlor, irgarol and diuron was evaluated in Pacific oyster (Crassostrea gigas) gametes or embryos exposed to concentrations of pesticides ranging from 0.1× to 1000×, with 1× corresponding to environmental concentrations of the three studied pesticides in Arcachon Bay (France). Exposures were performed on (1) spermatozoa alone (2) oocytes alone and (3) both spermatozoa and oocytes, and adverse effects on fertilization success and offspring development were recorded. The results showed that the fertilizing capacity of spermatozoa was significantly affected after gamete exposure to pesticide concentrations as low as 1× of irgarol and diuron and 10× of metolachlor. The offspring obtained from pesticide-exposed spermatozoa displayed a dose-dependent increase in developmental abnormalities. In contrast, treating oocytes with pesticide concentrations up to 10× did not alter fertilization rate and offspring quality. However, a significant decline in fertilization success and increase in abnormal D-larvae prevalence were observed at higher concentrations 10× (0.1 μg L(-1)) for S-metolachlor and 100× for irgarol (1.0 μg L(-1)) and diuron (4.0 μg L(-1)). Irgarol, diuron and S-metolachlor also induced a dose-dependent increase in abnormal D-larvae prevalence when freshly fertilized embryos were treated with pesticide concentrations as low as concentration of 1× (0.01 μg L(-1) for irgarol or S-metolachlor, and 0.04 μg L(-1) for diuron). The two bioassays on C. gigas spermatozoa and embryos displayed similar sensitivities to the studied pesticides while oocytes were less sensitive. Diuron, irgarol and S-metolachlor induced spermiotoxicity and embryotoxicity at environmentally relevant concentrations and therefore might be

  16. Sex tourism in Thailand.

    Science.gov (United States)

    Van Kerkwijk, C

    1992-01-01

    Many foreigners visit Thailand in search of sex. While long-distance tourism was long enjoyed by members of more privileged social classes, even the lower economical classes of Japan, Malaysia, Europe, America, and Australia can now afford to travel over long distances. This relatively new breed of tourist is more likely to be of lower socioeconomic and educational status and less likely to use condoms when having sex. An estimated 30,000 sex workers are active in Bangkok, of whom 7000/10,000 are females who work specifically in the tourism sector. 1/2-1/3 of the 600 commercial sex establishments in the city are visited by foreigners. Phuket, Pattaya, Koh Samui, and Chiangmai are also well-frequented by sex tourists. Overall, a large, diverse, inexpensive, and accessible commercial sex market exists in Thailand. One may meet sex workers quasi-ubiquitously and be assured to find someone capable of meeting one's sexual needs. With these attributes, Thailand strongly attracts tourists in search of sex. A certain degree of recklessness also prevails among those on vacation. Away from the peers and social mores of their native lands, tourists may engage in sexually activities without criticism. Likewise, Thai sex workers who cater to foreigners, especially females, enjoy more freedom and control in sexual relations than their peers who work among nationals. Neither single nor married women in Thailand are allowed much sexual freedom and are traditionally expected to be obliging docile, and submissive. The greater than normal personal latitude enjoyed by both sex worker and foreigner lead to more negotiation on condom use and overall lower use. As such, Thailand's commercial sex market with foreigners' involvement therein threatens to spread HIV to many other countries throughout the world.

  17. 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

  18. 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

  19. Annual variation in the levels of transcripts of sex-specific genes in the mantle of the common mussel, Mytilus edulis.

    Directory of Open Access Journals (Sweden)

    Sandhya Anantharaman

    Full Text Available Mytilus species are used as sentinels for the assessment of environmental health but sex or stage in the reproduction cycle is rarely considered even though both parameters are likely to influence responses to pollution. We have validated the use of a qPCR assay for sex identification and related the levels of transcripts to the reproductive cycle. A temporal study of mantle of Mytilus edulis found transcripts of male-specific vitelline coat lysin (VCL and female-specific vitelline envelope receptor for lysin (VERL could identify sex over a complete year. The levels of VCL/VERL were proportional to the numbers of sperm/ova and are indicative of the stage of the reproductive cycle. Maximal levels of VCL and VERL were found in February 2009 declining to minima between July - August before increasing and re-attaining a peak in February 2010. Water temperature may influence these transitions since they coincide with minimal water temperature in February and maximal temperature in August. An identical pattern of variation was found for a cryptic female-specific transcript (H5 but a very different pattern was observed for oestrogen receptor 2 (ER2. ER2 varied in a sex-specific way with male > female for most of the cycle, with a female maxima in July and a male maxima in December. Using artificially spawned animals, the transcripts for VCL, VERL and H5 were shown to be present in gametes and thus their disappearance from mantle is indicative of spawning. VCL and VERL are present at equivalent levels in February and July-August but during gametogenesis (August to January and spawning (March to June VCL is present at lower relative amounts than VERL. This may indicate sex-specific control mechanisms for these processes and highlight a potential pressure point leading to reduced reproductive output if environmental factors cause asynchrony to gamete maturation or release.

  20. Insects and sex

    NARCIS (Netherlands)

    Beukeboom, Leo

    2005-01-01

    Most organisms reproduce sexually, but the evolution of sexual reproduction is not yet well understood. Sexual reproduction leads to new variation and adaptations to the environment, but sex is also costly. Some insects reproduce without sex through parthenogenesis or paedogenesis. Almost all sexual

  1. Sex Away from Home

    Science.gov (United States)

    Greenwald, Harold

    1971-01-01

    The reasons why people who are normally truthful to their spouses engage in sex away from home are discussed. These reasons can include loneliness, ego building or the opportunity to have homosexual relations. Sex away from home is likely to increase since the number of people traveling is increasing. (Author/CG)

  2. Single-Sex Classrooms

    Science.gov (United States)

    Protheroe, Nancy

    2009-01-01

    Although single-sex education was once the norm in the U.S., the practice has largely been confined to private schools for more than a century. However, with the introduction of the final version of the U.S. Department of Education's so-called single-sex regulations in 2006, public schools were allowed greater flexibility to offer single-sex…

  3. Sex Education Materials.

    Science.gov (United States)

    Singer-Magdoff, Laura

    1969-01-01

    After briefly discussing the philosophy of sex education and appraising generally the nature of the instructional methods and materials currently in use in the schools, the author provides brief but incisive reviews of a number of films, filmstrips, and other instructional materials dealing with sex. The reviews are continued in the succeeding…

  4. Impact of consanguineous marriages and degrees of inbreeding on fertility, child mortality, secondary sex ratio, selection intensity, and genetic load: a cross-sectional study from Northern India.

    Science.gov (United States)

    Fareed, Mohd; Kaisar Ahmad, Mir; Azeem Anwar, Malik; Afzal, Mohammad

    2017-01-01

    The aim of our study was to understand the relationship between consanguineous marriages and reproductive outcomes. A total of 999 families were recruited from five Muslim populations of Jammu region. Family pedigrees were drawn to access the family history and inbreeding status in terms of coefficient of inbreeding (F). Fertility, mortality, secondary sex ratio, selection intensity, and lethal equivalents were measured using standard methods. The significant differences for gross fertility was found to be higher among inbred groups as compared to the unrelated families (P consanguineous families of all populations in comparison with the non-consanguineous family groups. Moreover, the prenatal and postnatal child mortality rates (i.e., U5MR and U18MR) have presented a persuasive increase with an upsurge in the homozygosity level. The mortality rate was found to be maximum among families with the highest value of coefficient of inbreeding (F). The selection intensity (SI) also showed inflations among families with respect to their increasing inbreeding coefficients. The greater values of lethal equivalents per gamete (LEs/gamete) were observed for autosomal inheritance in comparison with sex-linked inheritance. Our conclusive assessment brings out the deleterious consequence of consanguineous marriages on reproductive outcomes.

  5. MPK-1 ERK controls membrane organization in C. elegans oogenesis via a sex-determination module.

    Science.gov (United States)

    Arur, Swathi; Ohmachi, Mitsue; Berkseth, Matt; Nayak, Sudhir; Hansen, David; Zarkower, David; Schedl, Tim

    2011-05-17

    Tissues that generate specialized cell types in a production line must coordinate developmental mechanisms with physiological demand, although how this occurs is largely unknown. In the Caenorhabditis elegans hermaphrodite, the developmental sex-determination cascade specifies gamete sex in the distal germline, while physiological sperm signaling activates MPK-1/ERK in the proximal germline to control plasma membrane biogenesis and organization during oogenesis. We discovered repeated utilization of a self-contained negative regulatory module, consisting of NOS-3 translational repressor, FEM-CUL-2 (E3 ubiquitin ligase), and TRA-1 (Gli transcriptional repressor), which acts both in sex determination and in physiological demand control of oogenesis, coordinating these processes. In the distal germline, where MPK-1 is not activated, TRA-1 represses the male fate as NOS-3 functions in translational repression leading to inactivation of the FEM-CUL-2 ubiquitin ligase. In the proximal germline, sperm-dependent physiological MPK-1 activation results in phosphorylation-based inactivation of NOS-3, FEM-CUL-2-mediated degradation of TRA-1 and the promotion of membrane organization during oogenesis. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Sex: a sensitive issue.

    Science.gov (United States)

    1997-01-01

    Health care workers and educators may need to improve their skills in discussing sensitive issues in order to elicit and understand what influences people's attitudes toward sex. While the health worker may be bent upon preventing HIV infection, advising on family planning, or teaching youth about sexual relationships, his or her audience may have other priorities. A good counselor/teacher must learn what people's concerns are and discuss sexual health within that context. It can be difficult talking about sex because sex is a private concern and many people are embarrassed discussing it. Even sex partners often find it difficult to talk to each other about sex. Appropriate communication techniques vary depending upon the situation. It depends upon whether one is addressing people on an individual basis or in groups, which people are being addressed, which organization one is representing, and what one's role is. Good communication is a two-way sharing of information. The different stages of life, common beliefs and myths, culture and religion, relationships between men and women, reasons for having sex, and sex practices are discussed.

  7. Making Healthy Decisions About Sex

    Science.gov (United States)

    ... For Teens: How to Make Healthy Decisions About Sex Page Content Article Body Before you decide to ... alcohol or use drugs. Are You Ready for Sex? Sex can change your life and relationships. Having ...

  8. Dyspareunia: Painful Sex for Women

    Science.gov (United States)

    ... Safety Injury Rehabilitation Emotional Well-Being Mental Health Sex and Birth Control Sex and Sexuality Birth Control Family Health Infants and ... Share Print What is dyspareunia? Dyspareunia is painful sex for women. Also, it causes pain during tampon ...

  9. Hepatitis C: Sex and Sexuality

    Science.gov (United States)

    ... with Hepatitis » Sex and Sexuality: Entire Lesson Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... hepatitis C virus through sex. Can you pass hepatitis C to a sex partner? Yes, but it ...

  10. Sex education in Portugal.

    Science.gov (United States)

    Frade, A; Vilar, D

    1991-05-01

    The article on sex education in Portugal covers background, the educational system, the clashes of the 1960's over sex education, the Committee for the Study of Sexuality and Education (CSSE), the policies, politics and social movements during the period 1974 - 1984, the discussions in Parliament, the 1988 Reform of the Educational System, the Family Planning Association (FPA) and sex education, and the future role of the FPA. It was not until the institution of the multiparity parliamentary system in 1974 that discussing social and political changes was possible, culminating in 1984 with new legislation on abortion, family planning, and sex education. School reform came in 1987/8 with the Ministry of Education primarily responsible for curricula. The 1960's brought with it the influence of the Catholic Church. Change came in the form of progressivism among Catholics who replaced dogma with dialogue and listening. Sex education was considered as preparation for marriage, but masturbation, contraception, and prostitution were also discussed. In addition, the founder of FPA chaired the CSSE in 1971 and opened up debate on sex issues and drafted a bill to establish co-education in Portuguese schools. The revolution of 1974 brought an end to censorship and brought forth a policy of developing family planning. Changed in the Family Code gave women greater equality. UNFPA supported teacher training in non-sexist education. With human reproduction included in the natural sciences, there was still no school sex education policy and contraception was only sometimes represented in the biology curriculum. The focus of FPA was on contraception and abortion. Finally in the 1980's, the first sex education programs were developed for out-of-school youth. Even though in the 1970's there were leftists groups promoting sex education, it took leftist parliamentary power to get legislation on sex education in the schools adopted. The Ministry of Education however was pressured by the

  11. Gender and gonadal maturity stage identification of captive Chinese sturgeon, Acipenser sinensis, using ultrasound imagery and sex steroids.

    Science.gov (United States)

    Du, Hao; Zhang, Xiaoyan; Leng, Xiaoqian; Zhang, Shuhuan; Luo, Jiang; Liu, Zhigang; Qiao, Xingmei; Kynard, Boyd; Wei, Qiwei

    2017-05-01

    Long lifespan and late maturation make it difficult to establish gamete maturity and breeding age of captive endangered Chinese sturgeon, Acipenser sinensis. This greatly handicaps timely breeding and future conservation stocking efforts. We used ultrasound imagery and sex steroids to determine the gender and gonadal maturity stage of captive Chinese sturgeon (age, 10-17years old). The echogenicity of the reproductive organs and the respective morphology of the gonads were described and two quantitative parameters p o (proportion of the ovary to the entire reproductive organs) and d (thickness of the reproductive organs) were measured to characterize sex and maturity stage of Chinese sturgeon. Females were accordingly placed fish into several categories: F II (F II - , F II , F II + ), F III (F III , F III + ) and F IV (F IV , F IV + ) and F VI and males as M II , M III , M IV , M V and M VI . The accuracy of gender and maturity stage determination provided by ultrasonographic methods was 72.7% for F II - ovary (n=11) and 76.2% for M II testis (n=42). Accuracy of sex and maturity determination using only serum sex steroid of testosterone (T) and estradiol-17β (E 2 ) was low (58-73%, depending on maturity stage). However, when the two methods were used together, accuracy increased sharply, especially for immature (II stage) females. In summary, of 151 Chinese sturgeon, whose sex and maturity stage were independently confirmed, 88.1% (n=133), 62.9% (n=95), and 96.7% (n=146) were successfully sexed and staged using ultrasound, sex steroids, or both methods, respectively. The results provide reliable non-invasive techniques for determining sex and gonadal maturation of captive Chinese sturgeon. These methods can track individual gonad characteristics over multi-year reproductive cycles, which will assist captive broodstock management, artificial reproduction, and future conservation stocking. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Sex, Deportation and Rescue

    DEFF Research Database (Denmark)

    Plambech, Sine

    2017-01-01

    recirculating the claim that human trafficking is the “third largest” criminal economy after drugs and weapons. Based on ethnographic fieldwork among Nigerian sex worker migrants conducted in Benin City, Nigeria, in 2011 and 2012, this study brings together four otherwise isolated migration economies......This contribution explores the economies interlinked by the migration of Nigerian women sex workers. The literature and politics of sex work migration and human trafficking economies are commonly relegated to the realm that focuses on profits for criminal networks and pimps, in particular...... – facilitation, remittances, deportation, and rescue – and suggests that we have to examine multiple sites and relink these in order to more fully understand the complexity of sex work migration. Drawing upon literature within transnational feminist analysis, critical human trafficking studies, and migration...

  13. 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.

  14. Commentary Sex determination

    Indian Academy of Sciences (India)

    PRAKASH KUMAR G

    2008-01-31

    ZW is reserved for female heterogamety.) The Radder et al study used lab incubation regimes that mimic temperature profiles of cool natural nests, so temperature probably determines sex at least occasionally in nature.

  15. Female Sex Tourism

    OpenAIRE

    Mc Intyre, Maria Kleivan

    2017-01-01

    ABSTRACT This project explores the phenomenon of North American and Western European women, who travel to the Global South and engage in sexual encounters with the local men. This project has positioned itself as a postcolonial critique, arguing that female sex tourism is a form of neocolonialism. It has also investigated the term romance tourism, where it has found that as a result of essentialist gender stereotyping, the female version of sex tourism has been titled ‘romance tourism’. The p...

  16. Sex and Horror

    OpenAIRE

    Jones, Steve

    2017-01-01

    The combination of sex and horror may be disquieting to many, but the two are natural (if perhaps gruesome) bedfellows. In fact, sex and horror coincide with such regularity in contemporary horror fiction that the two concepts appear to be at least partially intertwined. The sex–horror relationship is sometimes connotative rather than overt; examples of this relationship range from the seduction overtones of 'Nosferatu' and the juxtaposition of nudity and horror promised by European exploitat...

  17. Gametic phase disequilibrium between the syntenic multiallelic HTG4 and HMS3 markers widely used for parentage testing in Thoroughbred horses.

    Science.gov (United States)

    Machado, Filipe Brum; de Vasconcellos Machado, Luana; Bydlowski, Cynthia Rachid; Bydlowski, Sergio Paulo; Medina-Acosta, Enrique

    2012-02-01

    Validation of parentage and horse breed registries through DNA typing relies on estimates of random match probabilities with DNA profiles generated from multiple polymorphic loci. Of the twenty-seven microsatellite loci recommended by the International Society for Animal Genetics for parentage testing in Thoroughbred horses, eleven are located on five chromosomes. An important aspect in determining combined exclusion probabilities is the ascertainment of the genetic linkage status of syntenic markers, which may affect reliable use of the product rule in estimating random match probabilities. In principle, linked markers can be in gametic phase disequilibrium (GD). We aimed at determining the extent, by frequency and strength, of GD between the HTG4 and HMS3 multiallelic loci, syntenic on chromosome 9. We typed the qualified offspring (n (1) = 27; n (2) = 14) of two Quarter Bred stallions (registered by the Brazilian Association of Quarter Horse Breeders) and 121 unrelated horses from the same breed. In the 41 informative meioses analyzed, the frequency of recombination between the HTG4 and HMS3 loci was 0.27. Consistent with genetic map distances, this recombination rate does not fit to the theoretical distribution for independently segregated markers. We estimated sign-based D' coefficients as a measure of GD, and showed that the HTG4 and HMS3 loci are in significant, yet partial and weak, disequilibrium, with two allele pairs involved (HTG4 M/HMS3 P, D'(+) = 0.6274; and HTG4 K/HMS3 P, D'(-) = -0.6096). These results warn against the inadequate inclusion of genetically linked markers in the calculation of combined power of discrimination for Thoroughbred parentage validation.

  18. AIDS and sex tourism.

    Science.gov (United States)

    Herold, E S; Van Kerkwijk, C

    1992-01-01

    Tourists traveling internationally lower their inhibitions and take greater risks than they would typically in their home cultures. Loneliness, boredom, and a sense of freedom contribute to this behavioral change. Some tourists travel internationally in search of sexual gratification. This motivation may be actively conscious or subconscious to the traveler. Billed as romantic with great natural beauty, Thailand, the Philippines, Brazil, the Dominican Republic, and Kenya are popular destinations of tourists seeking sex. The Netherlands and countries in eastern Europe are also popular. With most initial cases of HIV infection in Europe having histories of international travel, mass tourism is a major factor in the international transmission of AIDS. While abroad, tourists have sex with casual partners, sex workers, and/or other tourists. Far from all tourists, however, carry and consistently use condoms with these partners. One study found female and non white travelers to be less likely than Whites and males to carry condoms. The risk of HIV infection increases in circumstances where condoms are not readily available in the host country and/or are of poor quality. Regarding actual condom use, a study found only 34% of sex tourists from Switzerland to consistently use condoms while abroad. 28% of men in an STD clinic in Melbourne, Australia, reported consistent condom use in sexual relations while traveling in Asia; STDs were identified in 73% of men examined. The few studies of tourists suggest that a significant proportion engage in risky behavior while traveling. HIV prevalence is rapidly increasing in countries known as destinations for sex tourism. High infection rates are especially evident among teenage sex workers in Thailand. Simply documenting the prevalence of risky behavior among sex tourists will not suffice. More research is needed on travelers and AIDS with particular attention upon the motivating factors supporting persistent high-risk behavior.

  19. Teleology and Defining Sex.

    Science.gov (United States)

    Gamble, Nathan K; Pruski, Michal

    2018-07-01

    Disorders of sexual differentiation lead to what is often referred to as an intersex state. This state has medical, as well as some legal, recognition. Nevertheless, the question remains whether intersex persons occupy a state in between maleness and femaleness or whether they are truly men or women. To answer this question, another important conundrum needs to be first solved: what defines sex? The answer seems rather simple to most people, yet when morphology does not coincide with haplotypes, and genetics might not correlate with physiology the issue becomes more complex. This paper tackles both issues by establishing where the essence of sex is located and by superimposing that framework onto the issue of the intersex. This is achieved through giving due consideration to the biology of sexual development, as well as through the use of a teleological framework of the meaning of sex. Using a range of examples, the paper establishes that sex cannot be pinpointed to one biological variable but is rather determined by how the totality of one's biology is oriented towards biological reproduction. A brief consideration is also given to the way this situation could be comprehended from a Christian understanding of sex and suffering.

  20. Effects of Radiation on Germ Cells of Insects: Dominant Lethals, Gamete Inactivation and Gonial-Cell Killing; Effets des rayonnements sur les cellules germinales des insectes: letalite dominante, inactivation des gametes et destruction des cellules des gonades; Vozdejstvie radiatsii na polovye kletki nasekomykh: dominantnye letali, inaktivatsiya gamet i umershchvlenie polovykh kletok; Efectos de las radiaciones sobre las celulas germinales de los insectos: elementos letales dominantes, inactivacion de los gametos y exterminacion de las celulas gonadicas

    Energy Technology Data Exchange (ETDEWEB)

    Von Borstel, R. C. [Biology Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    1963-09-15

    Radiations and chemical mutagens kill cells in numerous ways: by one of several kinds of induced dominant lethality, by a direct inactivation of function as with sperm, and by genetically undefinable types of death which may or may not be related to dominant lethality per se. Also, chemical mutagens appear to exert a curious enhancement of the fertilizing capacity of sperm. The different stages of oflgenesis and spermatogenesis respond with unequal sensitivity to radiation, and individual cells pass through stages conferring as much as a 50-fold difference in sensitivity. Where species of Diptera, Hymenoptera and Coleoptera can be compared, a striking similarity of response to radiation can be observed, both to stage sensitivity and degree of response with dose. The silkworm, Bombyx mori (Lepidoptera), seems to be similar in most respects to representatives of the other orders in response of germ cells to radiation, but differs sharply in types of dominant lethality induced. Species having atypical genetic mechanisms (e.g.,the lecanoid system of Planococcus citri (Hemipt. : Coccidae) are special cases, and their responses to radiation are considerably modified from those of other species. For insect population control by the irradiation-of-male method, dominant lethality is as advantageous in species where matings are multiple as in species where mating occurs once. Sperm inactivation and gonial killing can be regarded as instances of true sterility and are maximally effective only in species where mating occurs once. For most efficient control, doses should be chosen which would induce maximum dominant lethality, minimum sperm inactivation and complete killing of gonial cells. These parameters are simple to determine by gamete viability measurements, irradiated and unirradiated population competition experiments and histological examination of gonia. (author) [French] Les rayonnements et les agents chimiques de mutation detruisent les cellules de nombreuses facons

  1. Same sex families and children

    OpenAIRE

    Mršević Zorica

    2009-01-01

    Introduction comprises the information on two main forms of same sex families, civic partnership (same sex partnership) and same sex marriage. Countries and various status modalities of legal regulations are mentioned. The main part of the text is dedicated to presentation of the findings of the most recent research on various aspects regarding children of same sex partnerships. It comprises presentations grouped in four main chapters: acceptance of same sex partnerships, acceptance of legal ...

  2. Sex Hormones and Tendon

    DEFF Research Database (Denmark)

    Hansen, Mette; Kjaer, Michael

    2016-01-01

    The risk of overuse and traumatic tendon and ligament injuries differ between women and men. Part of this gender difference in injury risk is probably explained by sex hormonal differences which are specifically distinct during the sexual maturation in the teenage years and during young adulthood....... The effects of the separate sex hormones are not fully elucidated. However, in women, the presence of estrogen in contrast to very low estrogen levels may be beneficial during regular loading of the tissue or during recovering after an injury, as estrogen can enhance tendon collagen synthesis rate. Yet...... has also been linked to a reduced responsiveness to relaxin. The present chapter will focus on sex difference in tendon injury risk, tendon morphology and tendon collagen turnover, but also on the specific effects of estrogen and androgens....

  3. Sex Disparities in Stroke

    DEFF Research Database (Denmark)

    Dehlendorff, Christian; Andersen, Klaus Kaae; Olsen, Tom Skyhøj

    2015-01-01

    between 2003 and 2012 (N=79 617), and the Danish Register of Causes of Death. Information was available on age, sex, marital status, stroke severity, stroke subtype, socioeconomic status, and cardiovascular risk profile. We studied only deaths due to the index stroke, with the assumption that death.......5%) or 1 month (6.9%), respectively. After the age of 60 years, women had more severe strokes than men. Up to ages in the mid-60s, no difference in the risk of death from stroke was seen between the 2 sexes. For people aged >65 years, however, the risk gradually became greater in men than in women...

  4. Sex steroids and neurogenesis.

    Science.gov (United States)

    Heberden, Christine

    2017-10-01

    The brain has long been known as a dimorphic organ and as a target of sex steroids. It is also a site for their synthesis. Sex steroids in numerous ways can modify cerebral physiology, and along with many processes adult neurogenesis is also modulated by sex steroids. This review will focus on the effects of the main steroids, estrogens, androgens and progestogens, and unveil some aspects of their partly disclosed mechanisms of actions. Gonadal steroids act on different steps of neurogenesis: cell proliferation seems to be increased by estrogens only, while androgens and progestogens favor neuronal renewal by increasing cell survival; differentiation is a common target. Aging is characterized by a cognitive deficiency, paralleled by a decrease in the rate of neuronal renewal and in the levels of circulating gonadal hormones. Therefore, the effects of gonadal hormones on the aging brain are important to consider. The review will also be expanded to related molecules which are agonists to the nuclear receptors. Sex steroids can modify adult neuronal renewal and the extensive knowledge of their actions on neurogenesis is essential, as it can be a leading pathway to therapeutic perspectives. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. How Sex Attitudes Develop

    Science.gov (United States)

    Arnstein, Helene S.

    1976-01-01

    Excerpt from "The Roots of Love" (Helene S. Arnstein, 1975). Book is concerned with feelings that are part of child's developmental stages. Included in excerpt are: genital self-discovery, masturbation, discovery of sex differences, and birth fantasies. Stresses importance of parent's feelings which are communicated to child.

  6. Sex differences in addiction.

    Science.gov (United States)

    Becker, Jill B

    2016-12-01

    Women exhibit more rapid escalation from casual drug taking to addiction, exhibit a greater withdrawal response with abstinence, and tend to exhibit greater vulnerability than men in terms of treatment outcome. In rodents, short-term estradiol intake in female rats enhances acquisition and escalation of drug taking, motivation for drugs of abuse, and relapse-like behaviors. There is also a sex difference in the dopamine response in the nucleus accumbens. Ovariectomized female rats exhibit a smaller initial dopamine increase after cocaine treatment than castrated males. Estradiol treatment of ovariectomized female rats enhances stimulated dopamine release in the dorsolateral striatum, but not in the nucleus accumbens, resulting in a sex difference in the balance between these two dopaminergic projections. In the situation where drug-taking behavior becomes habitual, dopamine release has been reported to be enhanced in the dorsolateral striatum and attenuated in the nucleus accumbens. The sex difference in the balance between these neural systems is proposed to underlie sex differences in addiction.

  7. Battle of the Sexes

    NARCIS (Netherlands)

    Bulte, E.H.; Tu, Q.; List, J.

    2015-01-01

    A vibrant literature has emerged that explores the economic implications of the sex ratio (the ratio of men to women in the population), including changes in fertility rates, educational outcomes, labor supply, and household purchases. Previous empirical efforts, however, have paid less attention to

  8. Sex education and ideals

    NARCIS (Netherlands)

    de Ruyter, D.J.; Spiecker, B.

    2008-01-01

    This article argues that sex education should include sexual ideals. Sexual ideals are divided into sexual ideals in the strict sense and sexual ideals in the broad sense. It is argued that ideals that refer to the context that is deemed to be most ideal for the gratification of sexual ideals in the

  9. Sex education in Cyprus.

    Science.gov (United States)

    Patsalides, N

    1991-05-01

    The objective of educating people on family planning and sexuality issues has been carried forth by the Family Planning Association of Cyprus (FPAC) since 1971. The promotion of sex education in schools has generated respect for their expertise. Sex education has reached the agenda of the General Assembly of Parliament only to be postponed due to the April 1991 end of term dismissal. A newly elected Parliament are not expected to act immediately. The Ministry of Education Committee on Health Education has been actively counseled since 1974, and most recently in their examination of the possibilities of school sex education and training of high school teachers. The Ministry of Education has authority over primary and secondary education, which is compulsory up to 3 years of secondary education. The approach of FPAC has been to work with parents first in education lectures at various well publicized locations. The agenda was to inform about FPAC, explain the purpose and meaning of sex education, and show the Merry-Go-Round educational film followed by a question and answer session. Eventually, presentations involved children with parent observation. In 1977, authorization from the Ministry of Education gave official approval to FPAC, but not on school premises. FPAC went directly to headmasters and gained support in primary schools to organize sessions on school premises, which successfully involved many primary schools even in the much needed rural areas. Home Economics and Child Care, offered in the 5th and 6th grades was the only vehicle for gaining permission to enter secondary schools. In Larnaca, secondary school headmasters at the 3rd and 6th grade levels permitted invitations which requested parental permission. Lecture topics on human reproduction, sex roles, and disease and contraception were also provided in a follow-up letter. Higher education levels were involved through youth clubs and evening lectures. In 1988, FPAC urged the Director General of the

  10. Sex and life expectancy.

    Science.gov (United States)

    Seifarth, Joshua E; McGowan, Cheri L; Milne, Kevin J

    2012-12-01

    A sexual dimorphism in human life expectancy has existed in almost every country for as long as records have been kept. Although human life expectancy has increased each year, females still live longer, on average, than males. Undoubtedly, the reasons for the sex gap in life expectancy are multifaceted, and it has been discussed from both sociological and biological perspectives. However, even if biological factors make up only a small percentage of the determinants of the sex difference in this phenomenon, parity in average life expectancy should not be anticipated. The aim of this review is to highlight biological mechanisms that may underlie the sexual dimorphism in life expectancy. Using PubMed, ISI Web of Knowledge, and Google Scholar, as well as cited and citing reference histories of articles through August 2012, English-language articles were identified, read, and synthesized into categories that could account for biological sex differences in human life expectancy. The examination of biological mechanisms accounting for the female-based advantage in human life expectancy has been an active area of inquiry; however, it is still difficult to prove the relative importance of any 1 factor. Nonetheless, biological differences between the sexes do exist and include differences in genetic and physiological factors such as progressive skewing of X chromosome inactivation, telomere attrition, mitochondrial inheritance, hormonal and cellular responses to stress, immune function, and metabolic substrate handling among others. These factors may account for at least a part of the female advantage in human life expectancy. Despite noted gaps in sex equality, higher body fat percentages and lower physical activity levels globally at all ages, a sex-based gap in life expectancy exists in nearly every country for which data exist. There are several biological mechanisms that may contribute to explaining why females live longer than men on average, but the complexity of the

  11. Influence of spawning procedure on gametes fertilization success in Salminus hilarii Valenciennes, 1850 (Teleostei: Characidae: Implications for the conservation of this species

    Directory of Open Access Journals (Sweden)

    Renato M. Honji

    2011-06-01

    Full Text Available Artificial reproduction and gamete fertilization were evaluated in Salminus hilarii wild and domesticated broodstocks. Wild and domesticated broodstocks were artificially induced to reproduction using a carp pituitary treatment. Four groups were considered: Group 1 (G1, fish caught in the wild maintained for three years in the same conditions as the domesticated broodstocks and spawned naturally; Group 2 (G2, broodstock born and raised in captivity and spawned naturally; Group 3 (G3, wild broodstocks, which were manually stripped for gamete collection and dry fertilization; and Group 4 (G4, domesticated males and females, also manually stripped. Oocytes, eggs, and larvae were sampled at different time intervals throughout embryonic development. Yolk sac absorption occurred approximately 24-29 h after hatching. Twenty-six h after hatching, the larvae mouths opened. Cannibalism was identified just 28-30 h after hatching. There was no morphological difference in embryonic development among all groups. The number of released eggs per gram of female was: G1: 83.3 ± 24.5 and G2: 103.8 ± 37.4; however, the fertilization success was lower in G2 (42.0 ± 6.37 % compared with G1 (54.7 ± 3.02% (P = 0.011. Hand-stripping of oocytes was not successful and the fertilization rate was zero. The reproduction of this species in captivity is viable, but it is necessary to improve broodstock management to enhance fertilization rates and obtain better fingerling production for restocking programs.A reprodução artificial e fertilização dos gametas foram avaliados em reprodutores selvagens e de cativeiro de Salminus hilarii. Reprodutores selvagens e de cativeiro foram induzidos artificialmente à reprodução utilizando hipófise de carpa. Quatros grupos foram considerados: Grupo 1 (G1, peixes capturados na natureza, mantidos por três anos nas mesmas condições de reprodutores de cativeiro e desovados naturalmente; Grupo 2 (G2, reprodutores nascidos e criados

  12. Disestablishing Sex: The Case for Released-Time Sex Education

    Science.gov (United States)

    Glanzer, Perry L.

    2011-01-01

    Allowing nonschool organizations to provide sex education in a released-time format would disestablish state-funded sex education and give families a choice in the sex education that would be provided for their children. Released-time programs, as originally conceived and currently practiced, allow students to be released for a period of time…

  13. Sex identification of Nigerian indigenous chicks using Auto-sexing ...

    African Journals Online (AJOL)

    Sexing has been a challenging task in Nigerian indigenous chickens due to the monomorphism of chicks which makes it impossible to distinguish the male from the female until eight weeks. . Therefore, this study was carried out to determine the sex of Nigerian indigenous chicks using the common auto-sexing methods.

  14. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries ... Coping with a New Injury Robin Dorman, PsyD Sex and Fertility After Spinal Cord Injury Diane M. ...

  15. Sex and Fertility After SCI

    Science.gov (United States)

    ... Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries ... Coping with a New Injury Robin Dorman, PsyD Sex and Fertility After Spinal Cord Injury Diane M. ...

  16. Low Sex Drive in Women

    Science.gov (United States)

    Low sex drive in women Overview Women's sexual desires naturally fluctuate over the years. Highs and lows commonly coincide ... used for mood disorders also can cause low sex drive in women. If your lack of interest ...

  17. SHBG (Sex Hormone Binding Globulin)

    Science.gov (United States)

    ... Links Patient Resources For Health Professionals Subscribe Search Sex Hormone Binding Globulin (SHBG) Send Us Your Feedback ... As Testosterone-estrogen Binding Globulin TeBG Formal Name Sex Hormone Binding Globulin This article was last reviewed ...

  18. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries Spinal Cord ... a New Injury Robin Dorman, PsyD Sex and Fertility After Spinal Cord Injury Diane M. Rowles, MS, ...

  19. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... sex after a spinal cord injury? play_arrow Can men and women still have sex after a ... menstruation after a spinal cord injury? play_arrow Can women still get pregnant after a spinal cord ...

  20. Hypnotic Psychotherapy with Sex Offenders

    Science.gov (United States)

    Moseley, Sullivan; Briggs, Wanda P.; Magnus, Virginia

    2005-01-01

    The authors review the literature on the prevalence of sex offenders; multiple treatment modalities; and implications of the use of hypnotic psychotherapy, coupled with cognitive behavioral treatment programs, for treating sex offenders. (Contains 2 tables.)

  1. Polybrominated diphenyl ethers affect the reproduction and development, and alter the sex ratio of zebrafish (Danio rerio)

    International Nuclear Information System (INIS)

    Han, X.B.; Yuen, Karen W.Y.; Wu, Rudolf S.S.

    2013-01-01

    Polybrominated diphenyl ethers (PBDEs) have been commonly used as flame retardants and now become ubiquitous in the global environment. Using zebrafish as a model, we tested the hypothesis that PBDEs may affect the reproduction and development of fish. Zebrafish were exposed to environmentally relevant concentrations of DE-71 (a congener of PBDE commonly found in the environment) throughout their whole life cycle, and the effects of DE-71 on gonadal development, gamete quality, fertilization success, hatching success, embryonic development and sex ratio were investigated. Despite gonadal development was enhanced, reductions in spawning, fertilization success, hatching success and larval survival rate were evident, while significant increases in malformation and percentage of male were also observed in the F1 generation. Our laboratory results suggest that PBDEs may pose a risk to reproductive success and alter the sex ratio of fish in environments highly contaminated with PBDEs. -- Highlights: •Zebrafish were exposed to PBDE from eggs to adults. •An increase in Gonadal-Somatic Index and enhanced gonadal development was enhanced. •Fertilization and hatching successes were reduced, while malformation was increased. •PBDE alters sex differentiation, leading to a male biased F1 population. •Environmental relevant concentrations of PBDE threaten natural fish populations. -- PBDE reduces fertilization and hatching successes, causes malformation and leads to a male biased F1 generation in fish

  2. Gametófitos y esporófitos jóvenes de cuatro especies de helechos del género Pteris (Pteridaceae naturalizadas en América

    Directory of Open Access Journals (Sweden)

    Olga G Martínez

    2010-03-01

    Full Text Available El género pantropical Pteris L. tiene 250 especies de la cuales 60 están en el continente Americano. Se estudió la morfogénesis de los gametófitos, y la morfología de los esporófitos jóvenes de cuatro especies: P. cretica, P. ensiformis, P. multifida y P.vittata, junto con un análisis palinológico que incluye la capacidad de las esporas de germinar. Los gametófitos se obtuvieron mediante técnicas de cultivo in vitro. Los esporófitos jóvenes se trasladaron a sustrato estéril de tierra y arena (3:1. Se usó el microscopio de luz y el de barrido (SEM. Se encontraron esporas con diferentes tipos de aperturas. La germinación ocurre entre 3-7 días y corresponde al tipo Vittaria. Se encontraron gametófitos filamentosos formados por 3-5 células en P. cretica, P. multifida y P. vittata y por 7-9 células en P. ensiformis. El desarrollo gametofítico ocurre de dos formas: tipo Adiantum y tipo Ceratopteris. Los gametófitos de P. ensiformis, P. multifida y P. vittata son monoicos y protándricos. P. cretica desarrolla gametófitos anteridiados. Los anteridios corresponden al tipo común de los helechos leptosporangiados, son cilíndricos en P. vittata y ovoides en las otras tres especies. Los cuellos de los arquegonios tienen 4 hileras con 4 células cada una. Los esporófitos se desarrollan después de los 3 meses de su siembra y su indumento es semejante a las plantas adultas. P. cretica presenta apogamia obligada.Gametophytes and young sporophytes of four species of the fern genus Pteris (Pteridaceae naturalized in the American continent. The pantropical fern genus Pteris L. has about 250 species of which 60 occur in the American continent. We studied the morphogenesis of the gametophyte, and the morphology of the young sporophytes of four species: P. cretica, P. ensiformis, P. multifida and P.vittata, together with a palynological analysis that includes the ability of spores to germinate. Gametophytes were obtained trough in vitro

  3. Sex Education with Young Children.

    Science.gov (United States)

    Koblinsky, Sally; And Others

    1980-01-01

    Discusses guidelines (developed by the Oregon State University Early Childhood Sex Education Project) for developing teacher-parent cooperation in providing sex education to young children. The guidelines concern how to talk about body differences and body functions; how to deal with masturbation, sex play and obscene language; and how to involve…

  4. YY Sex: a Polar Candidate

    Science.gov (United States)

    Gabdeev, M. M.; Shimanskiy, V. V.; Borisov, N. V.; Tazieva, Z. R.

    2017-06-01

    We present spectroscopic investigations of a cataclysmic variable star, YY Sex. There are some uncertainties in the classification of this object. We calculate Doppler maps for Hβ and HeII λ4686Å and show that there is no sign of disk accretion in YY Sex. Consequently, we conclude that YY Sex is a polar.

  5. Sex Education: Challenges and Choices

    Science.gov (United States)

    MacKenzie, Alison; Hedge, Nicki; Enslin, Penny

    2017-01-01

    Noting public concern about sexual exploitation, abuse and sexualisation, we argue that sex education in the UK needs revision. Choice is a feature of current sex education policy and, acknowledging that choice can be problematic, we defend its place in an approach to sex education premised on informed deliberation, relational autonomy, a…

  6. Sex Stereotyping Hurts All Kids.

    Science.gov (United States)

    Cutright, Melitta J.

    1991-01-01

    Sex stereotyping (raising boys and girls to be different because of their sex) begins at birth. The article reviews studies detailing sex stereotyping practices and offers suggestions on what parents can do to avoid them. A list of suggestions for raising children in a nonsexist way is included. (SM)

  7. Does oocyte banking for anticipated gamete exhaustion influence future relational and reproductive choices? A follow-up of bankers and non-bankers.

    Science.gov (United States)

    Stoop, D; Maes, E; Polyzos, N P; Verheyen, G; Tournaye, H; Nekkebroeck, J

    2015-02-01

    What is the nature of the relational status, reproductive choices and possible regret of a pioneer cohort of women that either considered or actually performed oocyte banking for anticipated gamete exhaustion (AGE)? Only half of the women who banked oocytes anticipate using them in the future but the experience with oocyte banking is overwhelmingly positive, with the majority of AGE bankers preferring to have it performed at a younger age. Most women who choose to cryopreserve oocytes for the prevention of age-related fertility decline are single and are hoping to buy time in their search for a suitable partner. The question of why some candidates actually embark on such treatment while others eventually prefer not to freeze remains unclear. There are no follow-up data available either on post-freezing changes in relational status, or on attitude towards the undergone treatment and the reproductive outcome. A retrospective cohort study was performed with 140 women who visited the outpatient clinic between 2009 and 2011. All women (mean age 36.7 ± SD 2.62) considered oocyte preservation for age-related infertility. At least 1 year after their initial visit (range 12-45 months), women were contacted by phone to participate in a standardized questionnaire developed to evaluate their actual relational and reproductive situation, their attitude towards banking and future reproductive plan. Eighty-six women (61.4%) completed at least one cryopreservation cycle. The non-bankers included 54 women who either preferred no treatment (n = 51) or attempted stimulation but cancelled because of poor response (n = 3). The response rate among bankers was 75.4% (65/86) while 55.8% (29/52) of the non-bankers were reached for interview. Among bankers, 50.8% of women think they will use the oocytes at some point, while 29.2% indicated that they currently consider the use of frozen oocytes less likely than anticipated at time of oocyte retrieval. However, although 95.4% would decide to

  8. The many costs of sex.

    Science.gov (United States)

    Lehtonen, Jussi; Jennions, Michael D; Kokko, Hanna

    2012-03-01

    Explaining the evolution of sex is challenging for biologists. A 'twofold cost' compared with asexual reproduction is often quoted. If a cost of this magnitude exists, the benefits of sex must be large for it to have evolved and be maintained. Focusing on benefits can be misleading, as this sidelines important questions about the cost of sex: what is the source of the twofold cost: males, genome dilution or both? Does the cost deviate from twofold? What other factors make sex costly? How should the costs of sex be empirically measured? The total cost of sex and how it varies in different contexts must be known to determine the benefits needed to account for the origin and maintenance of sex. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Sex Differences in HIV Infection.

    Science.gov (United States)

    Scully, Eileen P

    2018-04-01

    This review will outline the multilevel effects of biological sex on HIV acquisition, pathogenesis, treatment response, and prospects for cure. Potential mechanisms will be discussed along with future research directions. HIV acquisition risk is modified by sex hormones and the vaginal microbiome, with the latter acting through both inflammation and local metabolism of pre-exposure prophylaxis drugs. Female sex associates with enhanced risk for non-AIDS morbidities including cardiovascular and cerebrovascular disease, suggesting different inflammatory profiles in men and women. Data from research on HIV cure points to sex differences in viral reservoir dynamics and a direct role for sex hormones in latency maintenance. Biological sex remains an important variable in determining the risk of HIV infection and subsequent viral pathogenesis, and emerging data suggest sex differences relevant to curative interventions. Recruitment of women in HIV clinical research is a pathway to both optimize care for women and to identify novel therapeutics for use in both men and women.

  10. Adolescents' reported consequences of having oral sex versus vaginal sex.

    Science.gov (United States)

    Brady, Sonya S; Halpern-Felsher, Bonnie L

    2007-02-01

    The present study examined whether adolescents' initial consequences of sexual activity differ according to type of sexual activity and gender. Surveys were administered to 618 adolescents recruited from 2 public high schools in the autumn of ninth grade (2002) and at 6-month intervals until the spring of tenth grade (2004). Analyses were limited to the 275 adolescents (44%) who reported engaging in oral sex and/or vaginal sex at any assessment. Participants were 14 years of age at study entry, 56% female, and of diverse socioeconomic and ethnic backgrounds. In comparison with adolescents who engaged in oral sex and/or vaginal sex, adolescents who engaged only in oral sex were less likely to report experiencing a pregnancy or sexually transmitted infection, feeling guilty or used, having their relationship become worse, and getting into trouble with their parents as a result of sex. Adolescents who engaged only in oral sex were also less likely to report experiencing pleasure, feeling good about themselves, and having their relationship become better as a result of sex. Boys were more likely than girls to report feeling good about themselves, experiencing popularity, and experiencing a pregnancy or sexually transmitted infection as a result of sex, whereas girls were more likely than boys to report feeling bad about themselves and feeling used. Adolescents experience a range of social and emotional consequences after having sex. Our findings have implications for clinical practice and public health campaigns targeted toward youth.

  11. 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.

  12. Sex selection and restricting abortion and sex determination.

    Science.gov (United States)

    Zilberberg, Julie

    2007-11-01

    Sex selection in India and China is fostered by a limiting social structure that disallows women from performing the roles that men perform, and relegates women to a lower status level. Individual parents and individual families benefit concretely from having a son born into the family, while society, and girls and women as a group, are harmed by the widespread practice of sex selection. Sex selection reinforces oppression of women and girls. Sex selection is best addressed by ameliorating the situations of women and girls, increasing their autonomy, and elevating their status in society. One might argue that restricting or prohibiting abortion, prohibiting sex selection, and prohibiting sex determination would eliminate sex selective abortion. But this decreases women's autonomy rather than increases it. Such practices will turn underground. Sex selective infanticide, and slower death by long term neglect, could increase. If abortion is restricted, the burden is placed on women seeking abortions to show that they have a legally acceptable or legitimate reason for a desired abortion, and this seriously limits women's autonomy. Instead of restricting abortion, banning sex selection, and sex determination, it is better to address the practice of sex selection by elevating the status of women and empowering women so that giving birth to a girl is a real and positive option, instead of a detriment to the parents and family as it is currently. But, if a ban on sex selective abortion or a ban on sex determination is indeed instituted, then wider social change promoting women's status in society should be instituted simultaneously.

  13. Talking to Your Kids about Sex

    Science.gov (United States)

    ... Safety Injury Rehabilitation Emotional Well-Being Mental Health Sex and Birth Control Sex and Sexuality Birth Control Family Health Infants and ... Kids and Teens Talking to Your Kids About Sex Talking to Your Kids About Sex Share Print ...

  14. Sex workers talk about sex work: six contradictory characteristics of legalised sex work in Melbourne, Australia.

    Science.gov (United States)

    Begum, Sufia; Hocking, Jane S; Groves, Jan; Fairley, Christopher K; Keogh, Louise A

    2013-01-01

    Despite research suggesting that legal sex work is safe and that emotional risks and social stigma are of greater concern than health risks, much research on sex work has focused on health risks. Given the legalisation of sex work in Victoria, Australia, it is timely to look beyond health. Three focus groups were conducted with a total of 14 female sex workers on their experience of legal sex work, both positive and negative, and the social acceptability of their profession. Thematic analysis was used to identify the key ways that sex workers described sex work. Women saw legal sex work as safer than illegal sex work, but still not socially acceptable. However, they also described six contradictory elements of sex work, which was seen as: financially rewarding and entrapping; empowering and demeaning; increasing some opportunities while reducing others; flexible and demanding; offering both intimacy and competition; and leading to a 'double life'. While legalisation has improved the safety of sex work, stigma and discrimination persist.

  15. Fungal Sex: The Mucoromycota.

    Science.gov (United States)

    Lee, Soo Chan; Idnurm, Alexander

    2017-03-01

    Although at the level of resolution of genes and molecules most information about mating in fungi is from a single lineage, the Dikarya, many fundamental discoveries about mating in fungi have been made in the earlier branches of the fungi. These are nonmonophyletic groups that were once classified into the chytrids and zygomycetes. Few species in these lineages offer the potential of genetic tractability, thereby hampering the ability to identify the genes that underlie those fundamental insights. Research performed during the past decade has now established the genes required for mating type determination and pheromone synthesis in some species in the phylum Mucoromycota, especially in the order Mucorales. These findings provide striking parallels with the evolution of mating systems in the Dikarya fungi. Other discoveries in the Mucorales provide the first examples of sex-cell type identity being driven directly by a gene that confers mating type, a trait considered more of relevance to animal sex determination but difficult to investigate in animals. Despite these discoveries, there remains much to be gleaned about mating systems from these fungi.

  16. 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.

  17. Stress and sex: does cortisol mediate sex change in fish?

    Science.gov (United States)

    Goikoetxea, Alexander; Todd, Erica V; Gemmell, Neil J

    2017-12-01

    Cortisol is the main glucocorticoid (GC) in fish and the hormone most directly associated with stress. Recent research suggests that this hormone may act as a key factor linking social environmental stimuli and the onset of sex change by initiating a shift in steroidogenesis from estrogens to androgens. For many teleost fish, sex change occurs as a usual part of the life cycle. Changing sex is known to enhance the lifetime reproductive success of these fish and the modifications involved (behavioral, gonadal and morphological) are well studied. However, the exact mechanism behind the transduction of the environmental signals into the molecular cascade that underlies this singular process remains largely unknown. We here synthesize current knowledge regarding the role of cortisol in teleost sex change with a focus on two well-described transformations: temperature-induced masculinization and socially regulated sex change. Three non-mutually exclusive pathways are considered when describing the potential role of cortisol in mediating teleost sex change: cross-talk between GC and androgen pathways, inhibition of aromatase expression and upregulation of amh (the gene encoding anti-Müllerian hormone). We anticipate that understanding the role of cortisol in the initial stages of sex change will further improve our understanding of sex determination and differentiation across vertebrates, and may lead to new tools to control fish sex ratios in aquaculture. © 2017 Society for Reproduction and Fertility.

  18. Sex differentials in mortality.

    Science.gov (United States)

    1970-06-01

    The questions leing considered are whether a higher female than male mortality rate exists in Ceylon, India, and Pakistan, and whether this sex differential can account for the observed high male sex ratios. There is a choice between explaining the recorded masculinity of the Indian population by assuming that the subordinate position of women caused their omission from the census or that it caused their unrecorded death in childhood. The 1951 census report of India states that there is a traditional fondness for male issues in most parts of the country and a corresponding dislike for female children. However, a life table for India applied to the 1951 census gave a higher average female age at death 34.7 years as opposed to 33.5 years for male. Other estimates for India and Pakistan for the period 1951-1961 give 37.8 years for life expectancy for males and 36.98 for females. In 1953 the female death rate in Ceylon was over 80% higher than that of the males in the most reproductive ages, 20-29. In 1963 the female excess mortality at the same ages was still 25%, and in the age group 30-34 almost a 1/3 higher. In India the female death rate at ages 15-44 was 38% higher than that of the males in the 1958-1959 survey and as much as 174% higher in the Khanna rural survey, 1956-1960. In Pakistan a Population growth Estimate experiment conducted during 1962-1965 on a national probability sample has shown that in the ages 15-44 the female death rate was 75% higher than that of the males. High maternal mortality was the major reason. In addition, female mortality among young children over age 1 year was 24% higher in 1965 and 1963. There was little difference between the rates of mortality of the 2 sexes at age 45 and above. Recent trends in Ceylon show considerable improvement in maternal mortality which has reduced by 22% the ratio of female to male mortality at age 15-44. Also the ratio at ages 1-9 fell by 8%. to .1 of a year for every calendar year to 1980.

  19. Sex differences in drug abuse.

    Science.gov (United States)

    Becker, Jill B; Hu, Ming

    2008-01-01

    Sex differences are present for all of the phases of drug abuse (initiation, escalation of use, addiction, and relapse following abstinence). While there are some differences among specific classes of abused drugs, the general pattern of sex differences is the same for all drugs of abuse. Females begin regularly self-administering licit and illicit drugs of abuse at lower doses than do males, use escalates more rapidly to addiction, and females are at greater risk for relapse following abstinence. In this review, sex differences in drug abuse are discussed for humans and in animal models. The possible neuroendocrine mechanisms mediating these sex differences are discussed.

  20. Sex Reversal in Amphibians.

    Science.gov (United States)

    Flament, Stéphane

    2016-01-01

    Amphibians have been widely used to study developmental biology due to the fact that embryo development takes place independently of the maternal organism and that observations and experimental approaches are easy. Some amphibians like Xenopus became model organisms in this field. In the first part of this article, the differentiation of the gonads in amphibians and the mechanisms governing this process are reviewed. In the second part, the state of the art about sex reversal, which can be induced by steroid hormones in general and by temperature in some species, is presented. Also information about pollutants found in the environment that could interfere with the development of the amphibian reproductive apparatus or with their reproductive physiology is given. Such compounds could play a part in the amphibian decline, since in the wild, many amphibians are endangered species. © 2016 S. Karger AG, Basel.

  1. 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

  2. Sense about Sex: Media, Sex Advice, Education and Learning

    Science.gov (United States)

    Attwood, Feona; Barker, Meg John; Boynton, Petra; Hancock, Justin

    2015-01-01

    The media are widely acknowledged as important in sex and relationship education, but they are usually associated with "bad" effects on young people in contrast to the "good" knowledge represented by more informational and educational formats. In this paper we look at sex advice giving in newspapers, magazines and television in…

  3. Sex differences in adolescent depression: do sex hormones determine vulnerability?

    NARCIS (Netherlands)

    Naninck, E.F.G.; Lucassen, P.J.; Bakker, J.

    2011-01-01

    Depression is one of the most common, costly and severe psychopathologies worldwide. Its incidence, however, differs significantly between the sexes, and depression rates in women are twice those of men. Interestingly, this sex difference emerges during adolescence. Although the adolescent period is

  4. Sex and Age Differences in Attitude toward the Opposite Sex.

    Science.gov (United States)

    Silver, Rawley

    1997-01-01

    Examines fantasies about the opposite sex expressed by 116 children, adolescents, and adults responding to the Drawing from Imagination task of the Silver Drawing Test of Cognition and Emotion. Results indicate that both males and females expressed more negative than positive feelings toward subjects of the opposite sex. Males were more negative.…

  5. Sex Education: Talking to Toddlers and Preschoolers about Sex

    Science.gov (United States)

    Healthy Lifestyle Sexual health Sex education often begins with a child's curiosity about his or her body. Here's how to set the stage for ... Original article: http://www.mayoclinic.org/healthy-lifestyle/sexual-health/in-depth/sex-education/art-20044104 . Mayo Clinic Footer Legal Conditions and ...

  6. The trouble with sex differences.

    Science.gov (United States)

    Eliot, Lise

    2011-12-22

    Sex differences in the brain are real and clinically important but often grossly distorted in popular discourse. Considering the public's deep fascination with sex difference research and its impact on issues from mental health to education and workplace equity, neuroscientists should pay greater heed to its misappropriation and to studying how gender enculturation shapes neural function. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. Sex-work harm reduction.

    Science.gov (United States)

    Rekart, Michael L

    2005-12-17

    Sex work is an extremely dangerous profession. The use of harm-reduction principles can help to safeguard sex workers' lives in the same way that drug users have benefited from drug-use harm reduction. Sex workers are exposed to serious harms: drug use, disease, violence, discrimination, debt, criminalisation, and exploitation (child prostitution, trafficking for sex work, and exploitation of migrants). Successful and promising harm-reduction strategies are available: education, empowerment, prevention, care, occupational health and safety, decriminalisation of sex workers, and human-rights-based approaches. Successful interventions include peer education, training in condom-negotiating skills, safety tips for street-based sex workers, male and female condoms, the prevention-care synergy, occupational health and safety guidelines for brothels, self-help organisations, and community-based child protection networks. Straightforward and achievable steps are available to improve the day-to-day lives of sex workers while they continue to work. Conceptualising and debating sex-work harm reduction as a new paradigm can hasten this process.

  8. [Sex-linked juvenile retinoschisis].

    Science.gov (United States)

    François, P; Turut, P; Soltysik, C; Hache, J C

    1976-02-01

    About 13 observations of sexe linked juvenile retinoschisis, the authors describe the ophthalmoscopic, fluorographic and functional aspects of the disease whose caracteristics are:--its sexe linked recessive heredity; --its clinical characterestics associating: a microcystic macular degeneration, peripheral retinal lesions, vitreous body alterations, --an electroretinogram of the negative type.

  9. Sex Differences Reappraised: A Rebuttal

    Science.gov (United States)

    Tolor, Alexander; Brannigan, Gary G.

    1975-01-01

    This rebuttal of the criticisms made by Evans and Sperekas points to the fact that sex differences have been found by the authors on locus of control scales, that the purported sex-biased items in the Future Events Test are not necessarily outside the response repetoire of women, and the criticism of including female relevant items cannot be…

  10. Teaching Sex Education in Thailand

    Science.gov (United States)

    Kay, Noy S.; Jones, Megan R.; Jantaraweragul, Sudgasame

    2010-01-01

    The purposes of this study were to examine the current situation pertaining to the teaching of sex education and identify barriers to teaching sex education among Thai health education teachers. A survey questionnaire was administered to 193 health education teachers who participated in this study. The questionnaire was comprised of three parts:…

  11. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... arrow How should people deal with spasticity during sex? play_arrow What about positions and foreplay after a spinal cord injury? play_arrow What about orgasms and sensation during sex after a spinal cord injury? play_arrow What ...

  12. Moral Pluralism and Sex Education

    Science.gov (United States)

    Corngold, Josh

    2013-01-01

    How should common schools in a liberal pluralist society approach sex education in the face of deep disagreement about sexual morality? Should they eschew sex education altogether? Should they narrow its focus to facts about biology, reproduction, and disease prevention? Should they, in addition to providing a broad palette of information about…

  13. Sex in a test tube

    NARCIS (Netherlands)

    Pesce, Diego; Lehman, Niles; Visser, de Arjan

    2016-01-01

    The origin and evolution of sex, and the associated role of recombination, present a major problem in biology. Sex typically involves recombination of closely related DNA or RNA sequences,which is fundamentally a randomprocess that creates but also breaks up beneficial allele combinations.

  14. Sex reassignment surgery

    Directory of Open Access Journals (Sweden)

    Bižić Marta

    2015-01-01

    Full Text Available Transsexualism, or gender incongruence, presents a state in which a person's assigned sex at birth conflicts with their psychological gender. It is classified in International Classification of Diseases as F64. Treating these persons require multidisciplinary approach, including psychiatrist, endocrinologist, gynecologist, urologist, plastic and reconstructive surgeon. Genital reconstruction is the final step in transition, and can be performed when all other conditions required by World Professional Association for Transgender Health (WPATH are accomplished. Female to male sex reassignment surgery Several surgical procedures can be done in female to male transsexuals, including mastectomy, removal of female genitalia, metoidioplasty, scrotoplasty with implantation of testicular implants, as well as total phalloplasty. The current operative technique of metoidioplasty comprise the following steps: vaginal removal, the release of the ventral chordee and clitoral ligaments, straightening and lengthening of the clitoris, urethroplasty by combining buccal mucosa graft and genital flaps and scrotoplasty with insertion of testicle prostheses. The goal is to perform all these procedures in one stage, and that makes our team famous worldwide. Metoidioplasty results in excellent cosmetic outcome with completely preserved sensitivity and sexual arousal, enables voiding while standing, but without ability to penetrate due to small size of the neophallus. Considering these advantages, including low complication rate, patients often choose this option. For those who require bigger phallus which enables implantation of penile prosthesis, several surgical techniques have been reported using either available local vascularized tissue or microvascular tissue transfer. However, none of them satisfy all the goals of modern penile construction, i.e. reproducibility, tactile and erogenous sensation, a competent neourethra with a meatus at the top of the neophallus

  15. Constructions of Sex and Gender

    DEFF Research Database (Denmark)

    Schleicher, Marianne

    2011-01-01

    Responding to the ethical and performative call of Judith Butler not to propagate the sex- and gender-related violence of the imbedded discourse that we study, this article inquires into the discursive strategies of Jewish scripture by analysing how it orchestrates certain norms of sex and gender...... and make them serve the overall aim of securing cultural survival. Following this, it traces reflections on persons of ambiguous or indeterminate sex from rabbinic to modern Judaism so as to inquire into the rabbinic dependency on scripture when non-conforming individuals challenge its bipolar sex...... Jews and non-Jews are able to influence their own representations of sex and gender and thus liberate themselves from the normativity implied by scriptural discourse....

  16. Sex differences in primary hypertension

    Science.gov (United States)

    2012-01-01

    Men have higher blood pressure than women through much of life regardless of race and ethnicity. This is a robust and highly conserved sex difference that it is also observed across species including dogs, rats, mice and chickens and it is found in induced, genetic and transgenic animal models of hypertension. Not only do the differences between the ovarian and testicular hormonal milieu contribute to this sexual dimorphism in blood pressure, the sex chromosomes also play a role in and of themselves. This review primarily focuses on epidemiological studies of blood pressure in men and women and experimental models of hypertension in both sexes. Gaps in current knowledge regarding what underlie male-female differences in blood pressure control are discussed. Elucidating the mechanisms underlying sex differences in hypertension may lead to the development of anti-hypertensives tailored to one's sex and ultimately to improved therapeutic strategies for treating this disease and preventing its devastating consequences. PMID:22417477

  17. [Sex role and sports].

    Science.gov (United States)

    Darlison, E

    2000-11-01

    Gender inequality in all areas of life remains a global problem despite efforts over the past twenty years in particular to address the situation. In physical activity and sport the inequality between women and men is particularly pronounced in almost all countries, although it differs in degree. Two of the main reasons why inequality between women and men physical activity and sport is more extreme than in many other areas of social life are the result of the close association between the attributes required for sport and those associated with traditional concepts of stereotypical, hegemonic masculinity, and a lack of understanding of the difference between sex and gender. In sport and physical activity physical differences between men and women have been confused with socially constructed differences i.e. physical differences have been confused with gender differences, and this confusion has been used to justify women's lesser and limited participation at all levels. To achieve equality between women and men in physical activity and sport it will be essential that gender is identified and understood as a socially constructed and fluid concept which is a product of the relations between women and men. The fact that women bear children or are generally less physically powerful than men is not sufficient to justify why it is not considered appropriate for women to participate in certain forms of physical activity or why their participation is less valued than the participation of men. An understanding of gender and of the construction of gender relations is an important pre-requisite to addressing the inequality between women and men in physical activity and sport and in developing policies and programs which include, and are of equal benefit to both sexes. While more research on the benefits of participation in physical activity is needed, there is currently sufficient information available to identify the health related and social value of participation to both

  18. Same sex families and children

    Directory of Open Access Journals (Sweden)

    Mršević Zorica

    2009-01-01

    Full Text Available Introduction comprises the information on two main forms of same sex families, civic partnership (same sex partnership and same sex marriage. Countries and various status modalities of legal regulations are mentioned. The main part of the text is dedicated to presentation of the findings of the most recent research on various aspects regarding children of same sex partnerships. It comprises presentations grouped in four main chapters: acceptance of same sex partnerships, acceptance of legal recognition of the same sex partnerships, family plans of homosexual teenagers, and raising children within and by the same sex partners. Also the real life cases mirroring legal changes through their life destinies are presented, such is e.g. the Irish way to legalization of the same sex partnerships. In addition, a love story of two women crowned by giving birth of their four children is mentioned. Reasons against and negative reactions the author puts under the title Homophobia. In the Concluding remarks, the author presents the most recent examples of legal changes happened in Norway, Ecuador, and in the American states of California and Connecticut. It was also stated that in European countries of low birth rate, the same sex families are inevitably identified as one of demographically valuable source of creating and raising children, which is worthy to be supported, rather than being hindered without reason and discriminated. Although different than a model of heterosexual family, same sex partnerships neither are harrowing to traditional family values, nor reflex of any kind of promiscuous, antisocial behavior, avoidance of parenthood, and negation of family. Quite opposite, these families are an outcome of endeavors of homosexuals not to be deprived of family, parenthood and all of other values of stabile, monogamous, emotional/sexual socially accepted and legally recognized and regulated conventional family. .

  19. The sex and sex determination in Pyropia haitanensis (Bangiales, Rhodophyta).

    Science.gov (United States)

    Zhang, Yuan; Yan, Xing-hong; Aruga, Yusho

    2013-01-01

    Pyropia haitanensis has a biphasic life cycle with macroscopic gametophytic blade (n) and microscopic filamentous conchocelis (2n) phase. Its gametophytic blades have long been believed to be mainly dioecious. However, when crossing the red mutant (R, ♀) with the wild type (W, ♂), the parental colors were segregated in F1 blades, of which 96.1% were linearly sectored with 2-4 color sectors. When color sectors were excised from the color-sectored blades and cultured singly, 99.7% of the color sectors appeared to be unisexual with an equal sex ratio. Although the sex of color sector did not genetically link with its color, the boundaries of both sex and color sectors coincided precisely. About 87.9% of the examined color-sectored blades were monoecious and the percentage increased with the number of color sectors of a blade. The gametophytic blades from each conchocelis strain produced by parthenogenesis of the excised color sectors were unisexual and unicolor, showing the same sex and color as their original sectors. These results indicate that most of the sexually reproduced Py. haitanensis blades are monoecious, and their sex is controlled by segregation of a pair of alleles during meiosis of conchospore, forming a sex-sectored tetrad. During the subsequent development of blades, one or two lower cell(s) of the tetrad contribute mainly to rhizoid formation, and rarely show their sexual phenotype, leading to reduced frequency of full sex phenotype of the meiotic blades. Moreover, the aberrant segregations of sex genes or color genes in a few of F1 blades were probably due to gene conversions, but there was no sex transfer in Py. haitanensis.

  20. Talk to Your Kids about Sex

    Science.gov (United States)

    ... Topic En español Talk to Your Kids about Sex Browse Sections The Basics Overview Bodies and Puberty ... healthy expectations for their relationships. Talk about opposite-sex and same-sex relationships. When you talk about ...

  1. Fungal Sex: The Basidiomycota.

    Science.gov (United States)

    Coelho, Marco A; Bakkeren, Guus; Sun, Sheng; Hood, Michael E; Giraud, Tatiana

    2017-06-01

    Fungi of the Basidiomycota, representing major pathogen lineages and mushroom-forming species, exhibit diverse means to achieve sexual reproduction, with particularly varied mechanisms to determine compatibilities of haploid mating partners. For species that require mating between distinct genotypes, discrimination is usually based on both the reciprocal exchange of diffusible mating pheromones, rather than sexes, and the interactions of homeodomain protein signals after cell fusion. Both compatibility factors must be heterozygous in the product of mating, and genetic linkage relationships of the mating pheromone/receptor and homeodomain genes largely determine the complex patterns of mating-type variation. Independent segregation of the two compatibility factors can create four haploid mating genotypes from meiosis, referred to as tetrapolarity. This condition is thought to be ancestral to the basidiomycetes. Alternatively, cosegregation by linkage of the two mating factors, or in some cases the absence of the pheromone-based discrimination, yields only two mating types from meiosis, referred to as bipolarity. Several species are now known to have large and highly rearranged chromosomal regions linked to mating-type genes. At the population level, polymorphism of the mating-type genes is an exceptional aspect of some basidiomycete fungi, where selection under outcrossing for rare, intercompatible allelic variants is thought to be responsible for numbers of mating types that may reach several thousand. Advances in genome sequencing and assembly are yielding new insights by comparative approaches among and within basidiomycete species, with the promise to resolve the evolutionary origins and dynamics of mating compatibility genetics in this major eukaryotic lineage.

  2. Sex Hormones and Ischemic Stroke

    DEFF Research Database (Denmark)

    Holmegard, Haya N; Nordestgaard, Børge G; Jensen, Gorm B

    2016-01-01

    CONTEXT AND OBJECTIVE: Whether endogenous sex hormones are associated with ischemic stroke (IS) is unclear. We tested the hypothesis that extreme concentrations of endogenous sex hormones are associated with risk of IS in the general population. DESIGN, SETTING, AND PARTICIPANTS: Adult men (n...... = 4615) and women (n = 4724) with measurements of endogenous sex hormones during the 1981-1983 examination of the Copenhagen City Heart Study, Denmark, were followed for up to 29 years for incident IS, with no loss to follow-up. Mediation analyses assessed whether risk of IS was mediated through...

  3. Adolescents, sex, and the media.

    Science.gov (United States)

    Strasburger, Victor C

    2012-04-01

    In the absence of effective sex education in the United States, the media have arguably become the leading sex educator for children and teenagers. Considerable research now exists that attests to the ability of the media to influence adolescents' attitudes and beliefs about sex and sexuality. In addition, new research has found a significant link between exposure to sexual content in the media and earlier onset of sexual intercourse. Although there is little research on the behavioral effects of "new" media, they are discussed as well. Suggestions for clinicians, parents, the federal government, and the entertainment industry are provided.

  4. Whose crazy investment in sex?

    Science.gov (United States)

    Mandlis, Lane R

    2011-01-01

    By probing the processes of exclusion of transsexuals from the political sphere, this article offers contributions to social and political theory through an examination of the processes of exclusion from the category "human." This article considers how the erasure of investment in their own embodied sex constructs a platform from which to blame others for sex/gender variance, as well as to justify that blaming. Bringing together Giorgio Agamben, Georges Bataille, Judith Butler, and Nikolas Rose with transphobia, medicalization in psychiatry, law, and ethopolitics, this article questions whose investment in sexed embodiment counts and why that investment might be seen as "crazy."

  5. Disentangling the benefits of sex.

    Science.gov (United States)

    Roze, Denis

    2012-01-01

    Understanding the evolutionary advantage of sexual reproduction remains one of the most fundamental questions in evolutionary biology. Most of the current hypotheses rely on the fact that sex increases genetic variation, thereby enhancing the efficiency of natural selection; an important body of theoretical work has defined the conditions under which sex can be favoured through this effect. Over the last decade, experimental evolution in model organisms has provided evidence that sex indeed allows faster rates of adaptation. A new study on facultatively sexual rotifers shows that increased rates of sex can be favoured during adaptation to new environmental conditions and explores the cause of this effect. The results provide support for the idea that the benefits of increasing genetic variation may compensate for the short-term costs of sexual reproduction.

  6. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... a spinal cord injury? play_arrow What about oral sex after a spinal cord injury? ... injuries. The website does not provide medical advice, recommend or endorse health care products or services, or control the information ...

  7. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Spinal Cord Injury Guy W. Fried, MD Substance Abuse and Spinal Cord Injury Allen Heinemann, PhD How ... spinal cord injury? play_arrow Can men and women still have sex after a spinal cord injury? ...

  8. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Counseling Blog About Media Donate Spinal Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility ... injury? What is a Spinal Cord Injury? SCI Medical Experts People Living With SCI Personal Experiences By ...

  9. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... spinal cord injury? play_arrow Can men and women still have sex after a spinal cord injury? play_arrow How is sexual function in women affected by a spinal cord injury? play_arrow ...

  10. Sex differences, gender and addiction.

    Science.gov (United States)

    Becker, Jill B; McClellan, Michele L; Reed, Beth Glover

    2017-01-02

    This review discusses alcohol and other forms of drug addiction as both a sociocultural and biological phenomenon. Sex differences and gender are not solely determined by biology, nor are they entirely sociocultural. The interactions among biological, environmental, sociocultural, and developmental influences result in phenotypes that may be more masculine or more feminine. These gender-related sex differences in the brain can influence the responses to drugs of abuse, progressive changes in the brain after exposure to drugs of abuse and whether addiction results from drug-taking experiences. In addition, the basic laboratory evidence for sex differences is discussed within the context of four types of sex/gender differences. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  11. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Resources Peer Counseling Blog About Media Donate close search Understanding Spinal Cord Injury What is a Spinal ... male fertility? play_arrow Where can people get information on sex and fertility after a spinal cord ...

  12. Sex differences in cardiovascular function

    Czech Academy of Sciences Publication Activity Database

    Kolář, František; Ošťádal, Bohuslav

    2013-01-01

    Roč. 207, č. 4 (2013), s. 584-587 ISSN 1748-1708 Institutional support: RVO:67985823 Keywords : heart * vascular * risk factors * sex Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 4.251, year: 2013

  13. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Topic Resources Peer Counseling Blog About Media Donate Spinal Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries Spinal Cord Injury 101 David Chen, ...

  14. Sex and Fertility After SCI

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    Full Text Available ... Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries Spinal Cord Injury ... 2525 info@facingdisability.com SIGN UP FOR OUR NEWSLETTER Your email address * This iframe contains the logic ...

  15. Sex and Fertility After SCI

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    Full Text Available ... male fertility? play_arrow Where can people get information on sex and fertility after a spinal cord ... health care products or services, or control the information found on external websites. The Hill Foundation is ...

  16. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Topic Resources Peer Counseling Blog About Media Donate Spinal Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries Spinal Cord Injury 101 David ...

  17. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... after a spinal cord injury? play_arrow Can men and women still have sex after a spinal ... injury? play_arrow How is sexual function in men affected by a spinal cord injury ? play_arrow ...

  18. Potent radio-protective effects of vitamins E and C on radiation induced DNA damage in gametes leading to lower frequencies of chromosomal aberrations and micronuclei in subsequent embryos

    International Nuclear Information System (INIS)

    Hossein Mozdarani

    2007-01-01

    Complete text of publication follows. Objective: To compare the effects of parental and maternal exposure of NMRI mice with γ-rays on gametes in the absence or presence of vitamins E and C and subsequent cytogenetic damage in pre-implantation embryos generated from irradiated gametes. Materials and Methods: Male and female NMRI mice were whole body irradiated in the presence of 200 IU/Kg vitamin E and 100 μg/ml vitamin C. Various mating schemes were designed for mating of irradiated mice, e.g. mating irradiated male with non-irradiated female, irradiated female with non irradiated male or both male and female irradiated. About 68 h post coitus, 4-8-cell embryos were flushed out from oviducts and fixed on slides using standard methods in order to screen for chromosome abnormalities and micronuclei. Results: In control embryos, frequencies of abnormal metaphase and embryos with micronuclei was low and there was no significant difference between vitamins treated samples and controls. However there was an increase in both abnormal metaphases and micronuclei frequency in embryos generated after parental or maternal irradiation or both. Vitamin E effectively reduced the frequency of aneuploidy in all irradiated groups and vitamin C was very effective in reducing the frequencies of micronuclei. DRF calculated for both vitamins indicate that vitamin C is more potent than vitamin E in reducing clastogenic effects of gamma-rays in pre-implantation embryos. Conclusion: Data indicate that γ-irradiation affects spermatogenesis and preovulatory stage oocytes in male and female mice respectively. These effects might be due to DNA alterations in sperms and oocytes affecting meiotic segregations that may lead to chromosome abnormalities in subsequent embryos expressed as numerical chromosome abnormalities or micronuclei. Administration of vitamins E and C before irradiation effectively reduced the frequency of chromosomal abnormalities. The way these vitamins reduces genotoxic

  19. Gender socialization and sex affilation

    Directory of Open Access Journals (Sweden)

    Redžić Saduša F.

    2014-01-01

    Full Text Available The author's depth interviews with students of the University of Nis checked for the possibility of receptivity to sexual stereotypes and conditioning of sexual/gender socialization by sexual group affiliation. Examined the experiences and attitudes of students of both sexes regarding early gender socialization and it's characteristically stereotypes, stereotypes about dressing, instrumentalization of sexuality, the influence of parents/environment on the formation of sexual morality, own the gender socialization in the family, twin rules for the socialization of children of different gender and sex/gender roles in marriage. Belonging to the sex group has no effect on susceptibility to sexual stereotypes regarding early gender socialization and dressing. Difference may be seen in the effort to comment on and evaluate the wear behavior of girls more than a young man dressing, which may be an indicator for further research had sexual dimorphism in terms of dressing and nudity. It seems that the experience of respondents of both sexes are dependent primarily from the general family atmosphere (closeness, openness to communicate with each other, the absence of the traditional gender division of roles in the family/emotional distance from the parent of the opposite sex or of both parents, the rigidity, the strict division of gender roles in the family. In the first case, where both parents are involved in the upbringing of the child, relationships are intimate with both, and vice versa. Therefore, we can conclude about the lack of connection between the sex of the child and separated upbringing (traditional: the mother confides sexual education of women, a father of male child in the first case, and a link to another should only check to prove it. Sex does not condition susceptibility to stereotypes about education and gender roles. Traditionally, transitional and modern attitudes are equally represented in subjects of both sexes.

  20. Sex Differences in Drug Abuse

    OpenAIRE

    Becker, Jill B.; Hu, Ming

    2007-01-01

    Sex differences are present for all of the phases of drug abuse (initiation, escalation of use, addiction, and relapse following abstinence). While there are some differences among specific classes of abused drugs, the general pattern of sex differences is the same for all drugs of abuse. Females begin regularly self-administering licit and illicit drugs of abuse at lower doses than do males, use escalates more rapidly to addiction, and females are at greater risk for relapse following abstin...

  1. SEX DIFFERENCES, GENDER AND ADDICTION

    OpenAIRE

    Becker, Jill B.; McClellan, Michele L.; Reed, Beth Glover

    2017-01-01

    This review discusses alcohol/other drug addiction as both a sociocultural and biological phenomenon. Sex differences and gender are not solely determined by biology, nor are they entirely sociocultural. The interactions among biological, environmental, sociocultural and developmental influences result in phenotypes that may be more masculine or more feminine. These gender-related sex differences in the brain can influence the responses to drugs of abuse, progressive changes in the brain afte...

  2. Adaptive value of sex in microbial pathogens.

    Science.gov (United States)

    Michod, Richard E; Bernstein, Harris; Nedelcu, Aurora M

    2008-05-01

    Explaining the adaptive value of sex is one of the great outstanding problems in biology. The challenge comes from the difficulty in identifying the benefits provided by sex, which must outweigh the substantial costs of sex. Here, we consider the adaptive value of sex in viruses, bacteria and fungi, and particularly the information available on the adaptive role of sex in pathogenic microorganisms. Our general theme is that the varied aspects of sex in pathogens illustrate the varied issues surrounding the evolution of sex generally. These include, the benefits of sex (in the short- and long-term), as well as the costs of sex (both to the host and to the pathogen). For the benefits of sex (that is, its adaptive value), we consider three hypotheses: (i) sex provides for effective and efficient recombinational repair of DNA damages, (ii) sex provides DNA for food, and (iii) sex produces variation and reduces genetic associations among alleles under selection. Although the evolution of sex in microbial pathogens illustrates these general issues, our paper is not a general review of theories for the evolution of sex in all organisms. Rather, we focus on the adaptive value of sex in microbial pathogens and conclude that in terms of short-term benefits, the DNA repair hypothesis has the most support and is the most generally applicable hypothesis in this group. In particular, recombinational repair of DNA damages may substantially benefit pathogens when challenged by the oxidative defenses of the host. However, in the long-term, sex may help get rid of mutations, increase the rate of adaptation of the population, and, in pathogens, may infrequently create new infective strains. An additional general issue about sex illustrated by pathogens is that some of the most interesting consequences of sex are not necessarily the reasons for which sex evolved. For example, antibiotic resistance may be transferred by bacterial sex, but this transfer is probably not the reason sex

  3. Developmental expression of "germline"- and "sex determination"-related genes in the ctenophore Mnemiopsis leidyi.

    Science.gov (United States)

    Reitzel, Adam M; Pang, Kevin; Martindale, Mark Q

    2016-01-01

    An essential developmental pathway in sexually reproducing animals is the specification of germ cells and the differentiation of mature gametes, sperm and oocytes. The "germline" genes vasa, nanos and piwi are commonly identified in primordial germ cells, suggesting a molecular signature for the germline throughout animals. However, these genes are also expressed in a diverse set of somatic stem cells throughout the animal kingdom leaving open significant questions for whether they are required for germline specification. Similarly, members of the Dmrt gene family are essential components regulating sex determination and differentiation in bilaterian animals, but the functions of these transcription factors, including potential roles in sex determination, in early diverging animals remain unknown. The phylogenetic position of ctenophores and the genome sequence of the lobate Mnemiopsis leidyi motivated us to determine the compliment of these gene families in this species and determine expression patterns during development. Our phylogenetic analyses of the vasa, piwi and nanos gene families show that Mnemiopsis has multiple genes in each family with multiple lineage-specific paralogs. Expression domains of Mnemiopsis nanos, vasa and piwi, during embryogenesis from fertilization to the cydippid stage, were diverse, with little overlapping expression and no or little expression in what we think are the germ cells or gametogenic regions. piwi paralogs in Mnemiopsis had distinct expression domains in the ectoderm during development. We observed overlapping expression domains in the apical organ and tentacle apparatus of the cydippid for a subset of "germline genes," which are areas of high cell proliferation, suggesting that these genes are involved with "stem cell" specification and maintenance. Similarly, the five Dmrt genes show diverse non-overlapping expression domains, with no clear evidence for expression in future gametogenic regions of the adult. We also

  4. Sex reassignment surgery in Thailand.

    Science.gov (United States)

    Chokrungvaranont, Prayuth; Tiewtranon, Preecha

    2004-11-01

    Many years ago Thai society considered transsexualism (Gender identity disorder or Gender dysphoria) which is commonly known as Kathoey (a word originally used to denote hermaphrodites), Sao Prapet Song or Tut (as in 'Tootsie') were low class citizens, dirty dressing and had to hide in a dark corner selling their services as prostitutes. This made us unwilling to do sex reassignment surgery for this group of people because the idea of eradicating normal sexual organs for the purpose that was not accepted by the society. Consequently the authors have experience in cases where these people wandered seeking doctors who had no competency nor enough experience to do the surgery. The authors could not inhibit the desire of these people who usually suffer from gender identity disorder from strongly wishing to change their genital sex to the sex they want. The outcome of the surgery was not satisfactory for the patients. There were complications and sequelae which caused the authors to correct them later which might be more difficult than doing the original surgery. In addition there were more studies about the etiology and affect of the disorder on these people that changed the social point of view. The women who wanted to be a him and men who would like to be a her should be considered as patients who need to be cured to set the harmony about their genetic sex and the desire to be the opposite sex and also to be regarded by others as a member of that other sex. The treatments of transsexualism usually begin with conventional psychiatric and endocrinological treatment to adjust the mind to the body. For those who failed conservative treatment in adjusting the mind to the body then sex reassignment surgery will be the only way to transform their body to their mind and give the best result in properly selected patients. Preecha Tiewtranon, the pioneer in sex reassignment surgery in Thailand, did his transsexualism case in 1975 together with Dr. Prakob Thongpeaw. Sex

  5. 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.

  6. A Review of The Sex EDcyclopedia

    Science.gov (United States)

    Herman, Jeff; Andelloux, Megan

    2012-01-01

    While virtually all sex education books for teenagers focus on sexual health, Jo Langford's "The Sex EDcyclopedia" offers comprehensive and empowering information specifically for teen males about their sexuality and how it may be positively experienced. This review examines the strengths of "The Sex EDcyclopedia" as a sex education resource and…

  7. Sex work: a comparative study.

    Science.gov (United States)

    McCarthy, Bill; Benoit, Cecilia; Jansson, Mikael

    2014-10-01

    Explanations of adult involvement in sex work typically adopt one of two approaches. One perspective highlights a variety of negative experiences in childhood and adolescence, including physical and sexual abuse, family instability, poverty, associations with "pimps" and other exploiters, homelessness, and drug use. An alternative account recognizes that some of these factors may be involved, but underscores the contribution of more immediate circumstances, such as current economic needs, human capital, and employment opportunities. Prior research offers a limited assessment of these contrasting claims: most studies have focused exclusively on people working in the sex industry and they have not assessed the independent effects of life course variables central to these two perspectives. We add to this literature with an analysis that drew on insights from life course and life-span development theories and considered the contributions of factors from childhood, adolescence, and adulthood. Our comparative approach examined predictors of employment in sex work relative to two other low-income service or care work occupations: food and beverage serving and barbering and hairstyling. Using data from a study of almost 600 workers from two cities, one in Canada and the other in the United States, we found that both immediate circumstances and negative experiences from early life are related to current sex work involvement: childhood poverty, abuse, and family instability were independently associated with adult sex work, as were limited education and employment experience, adult drug use, and marital status.

  8. Sex selection: treating different cases differently.

    Science.gov (United States)

    Dickens, B M; Serour, G I; Cook, R J; Qiu, R-Z

    2005-08-01

    This paper contrasts ethical approaches to sex selection in countries where discrimination against women is pervasive, resulting in selection against girl children, and in countries where there is less general discrimination and couples do not prefer children of either sex. National sex ratio imbalances where discrimination against women is common have resulted in laws and policies, such as in India and China, to deter and prevent sex selection. Birth ratios of children can be affected by techniques of prenatal sex determination and abortion, preconception sex selection and discarding disfavored embryos, and prefertilization sperm sorting, when disfavored sperm remain unused. Incentives for son preference are reviewed, and laws and policies to prevent sex selection are explained. The elimination of social, economic and other discrimination against women is urged to redress sex selection against girl children. Where there is no general selection against girl children, sex selection can be allowed to assist families that want children of both sexes.

  9. Sex hormone binding globulin phenotypes

    DEFF Research Database (Denmark)

    Cornelisse, M M; Bennett, Patrick; Christiansen, M

    1994-01-01

    Human sex hormone binding globulin (SHBG) is encoded by a normal and a variant allele. The resulting SHBG phenotypes (the homozygous normal SHBG, the heterozygous SHBG and the homozygous variant SHBG phenotype) can be distinguished by their electrophoretic patterns. We developed a novel detection....... This method of detection was used to determine the distribution of SHBG phenotypes in healthy controls of both sexes and in five different pathological conditions characterized by changes in the SHBG level or endocrine disturbances (malignant and benign ovarian neoplasms, hirsutism, liver cirrhosis...... on the experimental values. Differences in SHBG phenotypes do not appear to have any clinical significance and no sex difference was found in the SHBG phenotype distribution....

  10. Sex differences in cough reflex.

    Science.gov (United States)

    Plevkova, J; Buday, T; Kavalcikova-Bogdanova, N; Ioan, I; Demoulin-Alexikova, S

    2017-11-01

    Majority of patients visiting cough clinics are postmenopausal women, who are affected by intractable cough for years. Why the cough reflex becomes exaggerated in women is not known. Basic research excludes females from the studies contributing to the sex bias which may be responsible for lack of understanding of "hypersensitive" cough in women. Biological and behavioural differences between women and men are the factors affecting cough physiology. Gender also shapes the patterns of behaviour and determines the character of environmental exposures which differs between sexes. The article offers an insight into the physiology of the cough, differences in the maturation of it and biological, social and behavioural factors contributing to the sex differences in cough. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Incarcerated Dutch Juvenile Sex Offenders Compared with Non-Sex Offenders

    Science.gov (United States)

    van Wijk, Anton Ph.; Vreugdenhil, Coby; van Horn, Joan; Vermeiren, Robert; Doreleijers, Theo A. H.

    2007-01-01

    There is some debate about whether or not sex offenders are similar to non-sex offenders with regard to family background (parental characteristics), personality, and psychopathology. The central aim of this study focused on the comparison of juvenile sex offenders and non-sex offenders. The sample consisted of incarcerated juvenile male sex (n =…

  12. The Stability of Same-Sex Cohabitation, Different-Sex Cohabitation, and Marriage

    Science.gov (United States)

    Lau, Charles Q.

    2012-01-01

    This study contributes to the emerging demographic literature on same-sex couples by comparing the level and correlates of union stability among 4 types of couples: (a) male same-sex cohabitation, (b) female same-sex cohabitation, (c) different-sex cohabitation, and (d) different-sex marriage. The author analyzed data from 2 British birth cohort…

  13. Learning about Sex: Resource Guide for Sex Educators. Revised Edition

    Science.gov (United States)

    Huberman, Barbara

    2011-01-01

    Whether you are someone new to the field of sex education, trying to start a library or resource center on adolescent sexual health, or an old pro, this guide should give you a basic orientation to what's available to support your work. These resources are important to advancing positive attitudes toward adolescent sexual health and the author…

  14. Sex Education: Talking to Your Teen about Sex

    Science.gov (United States)

    ... might miss the best opportunities. Instead, think of sex education as an ongoing conversation. Here are some ideas to help you get started — and keep the discussion going. Seize the moment. When a TV program or music video raises issues about responsible sexual behavior, use it ...

  15. Sex differences and sex similarities in disgust sensitivity

    NARCIS (Netherlands)

    Tybur, J.M.; Bryan, A.D.; Lieberman, D.L.; Caldwell Hooper, A.E.; Merriman, L.A.

    2011-01-01

    Across two studies, we test for sex differences in the factor structure, factor loadings, concurrent validity, and means of the Three Domain Disgust Scale. In Study 1, we find that the Three Domain Disgust Scale has indistinguishable factor structure and factor loadings for men and women. In Study

  16. Elusive Sex Acts: Pleasure and Politics in Norwegian Sex Education

    Science.gov (United States)

    Svendsen, Stine H. Bang

    2012-01-01

    While there is little political opposition towards sex education as such in Norway, recent attempts at reforming the subject reveal underlying heteronormative presumptions that seem resistant to reform. While a focus on homosexuality is included in the national curriculum at all levels of compulsory education, the sexual practices involved in…

  17. Destabilising Sex work and Intimacy?

    DEFF Research Database (Denmark)

    Spanger, Marlene

    politikfelt prostitution. Undersøgelsen trækker på poststrukturalistisk feministisk teori og er baseret på interviews med kvindelige thailandske migranter, der sælger sex, og socialarbejdere samt deltagende observationer og diverse dokumenter. Afhandlingen falder i to dele. Den første del er rammen for de...... fire artikler, som består af en introduktion, en teoretisk ramme, metodeovervejelser og konklusion samt et overordnet forskningsspørgsmål: Hvordan destabiliserer og reproducerer kvindelige thailandske migranter, der sælger sex i Danmark, det danske prostitutionspolitikfelts kategorier ’sexarbejde’ og...

  18. AIDS prevention in the sex industry.

    Science.gov (United States)

    Morgan-thomas, R; Overs, C

    1992-01-01

    Most sex work research examines the impact of HIV on prostitutes and on society and involves testing prostitutes for HIV antibodies, but it does not examine the role of others in the sex industry. Sex industry workers include female prostitutes, transvestites, transsexuals, and male prostitutes, bar and brothel owners, taxi drivers, sex workers' partners, and sex business managers. Since sex workers provide sexual services to clients, they are in a perfect position to teach them about sexual health. Society must recognize that we cannot wish the sex industry away and that we need an effective health promotion strategy now. Some successful relevant AIDS education campaigns provide us some guidelines on how to develop campaigns. Any campaign targeting the sex industry should also target the public. Sex workers should participate in developing health messages and educational activities. They should also participate in the project. Any campaign must deal with major obstacles to safer sexual practices of which sex workers are aware and be consulted. Common obstacles are client demand for unprotected sex and irregular and inadequate supply of inexpensive condoms. A health promotion strategy cannot be effective, however, if sex workers do not have access to social support and health care services. Health promotion workers should also encourage local authorities to end discrimination of sex workers so they can freely obtain needed services. In some countries, sex workers operate fantasy workshops providing peers with ideas to sell sex services which reduce the risk of HIV transmission. Other campaigns distribute safer sex messages on small cards, cigarette lighters, key rings, condom packages, and T shirts. Training of sex workers other than prostitutes to reinforce safer sex messages to clients is also effective, e.g., taxi drivers can say they will take a client to a woman who uses condoms rather than to a clean girl. Street theater and puppets have also successfully

  19. Enriching ploidy level diversity: the role of apomictic and sexual biotypes of Hieracium subgen. Pilosella (Asteraceae) that coexist in polyploid populations

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Rotreklová, O.; Krahulec, František; Rosenbaumová, Radka; Plačková, Ivana

    2009-01-01

    Roč. 44, č. 3 (2009), s. 281-306 ISSN 1211-9520 R&D Projects: GA ČR GA206/07/0059; GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : facultative apomixis * genome instability * hybrid swarms * residual sexuality * unreduced gametes Subject RIV: EF - Botanics Impact factor: 1.320, year: 2009

  20. Sex Pheromones of C. elegans Males Prime the Female Reproductive System and Ameliorate the Effects of Heat Stress.

    Directory of Open Access Journals (Sweden)

    Erin Z Aprison

    2015-12-01

    Full Text Available Pheromones are secreted molecules that mediate animal communications. These olfactory signals can have substantial effects on physiology and likely play important roles in organismal survival in natural habitats. Here we show that a blend of two ascaroside pheromones produced by C. elegans males primes the female reproductive system in part by improving sperm guidance toward oocytes. Worms have different physiological responses to different ratios of the same two molecules, revealing an efficient mechanism for increasing coding potential of a limited repertoire of molecular signals. The endogenous function of the male sex pheromones has an important side benefit. It substantially ameliorates the detrimental effects of prolonged heat stress on hermaphrodite reproduction because it increases the effectiveness with which surviving gametes are used following stress. Hermaphroditic species are expected to lose female-specific traits in the course of evolution. Our results suggest that some of these traits could have serendipitous utility due to their ability to counter the effects of stress. We propose that this is a general mechanism by which some mating-related functions could be retained in hermaphroditic species, despite their expected decay.

  1. Sex Pheromones of C. elegans Males Prime the Female Reproductive System and Ameliorate the Effects of Heat Stress

    Science.gov (United States)

    Aprison, Erin Z.; Ruvinsky, Ilya

    2015-01-01

    Pheromones are secreted molecules that mediate animal communications. These olfactory signals can have substantial effects on physiology and likely play important roles in organismal survival in natural habitats. Here we show that a blend of two ascaroside pheromones produced by C. elegans males primes the female reproductive system in part by improving sperm guidance toward oocytes. Worms have different physiological responses to different ratios of the same two molecules, revealing an efficient mechanism for increasing coding potential of a limited repertoire of molecular signals. The endogenous function of the male sex pheromones has an important side benefit. It substantially ameliorates the detrimental effects of prolonged heat stress on hermaphrodite reproduction because it increases the effectiveness with which surviving gametes are used following stress. Hermaphroditic species are expected to lose female-specific traits in the course of evolution. Our results suggest that some of these traits could have serendipitous utility due to their ability to counter the effects of stress. We propose that this is a general mechanism by which some mating-related functions could be retained in hermaphroditic species, despite their expected decay. PMID:26645097

  2. [Sex differences and anesthesiology: preface and comments].

    Science.gov (United States)

    Nishno, Takashi

    2009-01-01

    In this special issue, the topic of sex difference in the field of anesthesiology is featured. Eight subtopics are discussed including 1) sex differences in cardiovascular medicine, 2) perioperative cardiovascular management, 3) sex differences in the respiratory functions of the upper airway, 4) sex differences in the anesthetic management, 5) sex differences in pain, 6) sex differences in laboratory medicine, 7) sex differences in pharmacokinetics of anesthetics, and 8) postoperative nausea and vomiting. Although recent clinical and experimental studies have shown the existence of sex and/or gender differences in many fields of medicine, our knowledge of sex differences in anesthesiology is apparently insufficient. I believe that anesthesiologists should pay more attention to this topic to improve our daily practice of anesthesia.

  3. Sex, Lies and Video Games

    Science.gov (United States)

    Kearney, Paul; Pivec, Maja

    2007-01-01

    Sex and violence in video games is a social issue that confronts us all, especially as many commercial games are now being introduced for game-based learning in schools, and as such this paper polls teenage players about the rules their parents and teachers may or may not have, and surveys the gaming community, ie, game developers to parents, to…

  4. Will sex selection reduce fertility?

    Science.gov (United States)

    Leung, S F

    1994-01-01

    Population control is one of the primary policies applied against poverty in many low income countries. The widespread prevalence of son preference in some countries such as China and India, however, works against any reduction of fertility. This is so because parents often continue to have children until they obtain the number of sons which they desire. The bias against girls has also led to higher abortion and mortality rates of female children. It is frequently argued that if sex selection methods are made available to parents so that they can control the gender of their children, population growth would be lowered and women's welfare improved. The author investigates both theoretically and numerically the impact of sex selection on fertility. A static quantity-quality model of fertility is used to compare fertility choices when parents cannot choose the gender of children versus a situation in which parents can choose gender. Empirical data are drawn from the 1976 Malaysian Family Life Survey. Analysis found that whether sex selection reduces fertility depends upon the second and third derivatives of the utility function and the child expenditure function. A numerical dynamic analysis is also presented. The simulation shows, using empirical dynamic models of fertility and the Monte Carlo integration technique, that sex selection on the firstborn child among the Chinese in Malaysia could reduce fertility by about 3%.

  5. Studying Sex Prejudice in Children.

    Science.gov (United States)

    Olsen, Nancy J.; Willemsen, Eleanor W.

    1978-01-01

    Explores a methodology for studying sex prejudice in children. First-, third-, and fifth-grade students were asked to rate the performance of an eight-year-old child identified as a girl for half of the subjects and as a boy for the remaining half. (BD)

  6. A Talk on Sex Discrimination.

    Science.gov (United States)

    Evers, Irving C.

    The topic of this speech covers the 1972 amendments to Title VII of the Civil Rights Act of 1964 and the subsequent court cases dealing with sex discrimination. The cases discussed cover maternity leaves for tenured as well as untenured teachers and other public employees. The issues basic to these cases involve mandatory maternity leaves at…

  7. Sex, spite, and selfish genes

    Indian Academy of Sciences (India)

    Nature's oracle: the life and work of W. D. Hamilton. Ullica Segerstrale .... Stemming partly from his study of sex ratios, Hamilton later began moving on to .... any scientific biography, has to strike a balance between sci- ence and the personal ...

  8. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... oral medications for erectile dysfunction? play_arrow What do people do with a catheter during sex? play_arrow How ... after a spinal cord injury? play_arrow How do women deal with menstruation after a spinal cord ...

  9. Sex and the Imperfect Fungi.

    Science.gov (United States)

    Dyer, Paul S; Kück, Ulrich

    2017-06-01

    Approximately 20% of species in the fungal kingdom are only known to reproduce by asexual means despite the many supposed advantages of sexual reproduction. However, in recent years, sexual cycles have been induced in a series of emblematic "asexual" species. We describe how these discoveries were made, building on observations of evidence for sexual potential or "cryptic sexuality" from population genetic analyses; the presence, distribution, and functionality of mating-type genes; genome analyses revealing the presence of genes linked to sexuality; the functionality of sex-related genes; and formation of sex-related developmental structures. We then describe specific studies that led to the discovery of mating and sex in certain Candida , Aspergillus , Penicillium , and Trichoderma species and discuss the implications of sex including the beneficial exploitation of the sexual cycle. We next consider whether there might be any truly asexual fungal species. We suggest that, although rare, imperfect fungi may genuinely be present in nature and that certain human activities, combined with the genetic flexibility that is a hallmark of the fungal kingdom, might favor the evolution of asexuality under certain conditions. Finally, we argue that fungal species should not be thought of as simply asexual or sexual, but rather as being composed of isolates on a continuum of sexual fertility.

  10. Creativity and Psychopathology: Sex Matters

    Science.gov (United States)

    Martín-Brufau, Ramón; Corbalán, Javier

    2016-01-01

    The association between creativity and psychopathology has, for decades, been a focus of heated debate fuelled by contradictory findings. Nevertheless, the findings suggest complex associations between creativity and psychopathology. Other studies have investigated the association between creativity and sex, with inconsistent results. The aim of…

  11. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... arrow How does caregiving for your partner often affect romantic relationships? play_arrow What are the common treatments for ... play_arrow How does a spinal cord injury affect male fertility? play_arrow Where can people get information on sex and ... Contact Us Terms of Use Site Map ...

  12. 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

  13. 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

  14. Sex Discrimination in Employment Practices.

    Science.gov (United States)

    California Univ., Los Angeles. Univ. Extension.

    The conference on sex discrimination in employment practices was held at the University of California at Los Angeles in cooperation with the Women's Bureau of the Department of Labor. Speeches included: (1) "New Legislation--New Action" by Rosalind K. Loring and William Foster, (2) "Compliance Policies and Procedures for Business and Industry" by…

  15. Sex determination in the Hymenoptera

    NARCIS (Netherlands)

    Heimpel, George E.; de Boer, Jetske G.

    2008-01-01

    The dominant and ancestral mode of sex determination in the Hymenoptera is arrhenotokous parthenogenesis, in which diploid females develop from fertilized eggs and haploid males develop from unfertilized eggs. We discuss recent progress in the understanding of the genetic and cytoplasmic mechanisms

  16. The prostitutions: power and sex

    Directory of Open Access Journals (Sweden)

    Adele Nunziante Cesaro

    2013-06-01

    Full Text Available The contemporary scenario features many and unusual versions of the sexual mercenary exchange, articulating new dynamics of desire. Prostitution remains a “question” which interrogates the gender and the difference between the sexes. According to a Freudian perspective, the authors present some reflection on the forms of sexuality today.

  17. Usage of the Terms Prostitution, Sex Work, Transactional Sex, and Survival Sex: Their Utility in HIV Prevention Research.

    Science.gov (United States)

    McMillan, Karen; Worth, Heather; Rawstorne, Patrick

    2018-07-01

    This article considers the terms prostitution, sex work, transactional sex, and survival sex, the logic of their deployment and utility to research concerned with people who are paid for sex, and HIV. The various names for paid sex in HIV research are invested in strategically differentiated positionings of people who receive payment and emphasize varying degrees of choice. The terminologies that seek to distinguish a range of economically motivated paid sex practices from sex work are characterized by an emphasis on the local and the particular, efforts to evade the stigma attached to the labels sex worker and prostitute, and an analytic prioritizing of culture. This works to bestow cultural legitimacy on some locally specific forms of paid sex and positions those practices as artifacts of culture rather than economy. This article contends that, in HIV research in particular, it is necessary to be cognizant of ways the deployment of alternative paid sex categories relocates and reinscribes stigma elsewhere. While local identity categories may be appropriate for program implementation, a global category is necessary for planning and funding purposes and offers a purview beyond that of isolated local phenomena. We argue that "sex work" is the most useful global term for use in research into economically motivated paid sex and HIV, primarily because it positions paid sex as a matter of labor, not culture or morality.

  18. Same Sex Marriage and the Perceived Assault on Opposite Sex Marriage

    OpenAIRE

    Dinno, Alexis; Whitney, Chelsea

    2013-01-01

    BACKGROUND: Marriage benefits both individuals and societies, and is a fundamental determinant of health. Until recently same sex couples have been excluded from legally recognized marriage in the United States. Recent debate around legalization of same sex marriage has highlighted for anti-same sex marriage advocates and policy makers a concern that allowing same sex couples to marry will lead to a decrease in opposite sex marriages. Our objective is to model state trends in opposite sex mar...

  19. Epigenetic information in gametes: Gaming from before fertilization. Comment on ;Epigenetic game theory: How to compute the epigenetic control of maternal-to-zygotic transition; by Qian Wang et al.

    Science.gov (United States)

    Shi, Junchao; Zhang, Xudong; Liu, Ying; Chen, Qi

    2017-03-01

    In their interesting article [1] Wang et al. proposed a mathematical model based on evolutionary game theory [2] to tackle the fundamental question in embryo development, that how sperm and egg interact with each other, through epigenetic processes, to form a zygote and direct successful embryo development. This work is based on the premise that epigenetic reprogramming (referring to the erasure and reconstruction of epigenetic marks, such as DNA methylation and histone modifications) after fertilization might be of paramount importance to maintain the normal development of embryos, a premise we fully agree, given the compelling experimental evidence reported [3]. Wang et al. have specifically chosen to employ the well-studied DNA methylation reprogramming process during mammalian early embryo development, as a basis to develop their mathematical model, namely epigenetic game theory (epiGame). They concluded that the DNA methylation pattern in mammalian early embryo could be formulated and quantified, and their model can be further used to quantify the interactions, such as competition and/or cooperation of expressed genes that maximize the fitness of embryos. The efforts by Wang et al. in quantitatively and systematically analyzing the beginning of life apparently hold value and represent a novel direction for future embryo development research from both theoretical and experimental biologists. On the other hand, we see their theory still at its infancy, because there are plenty more parameters to consider and there are spaces for debates, such as the cases of haploid embryo development [4]. Here, we briefly comment on the dynamic process of epigenetic reprogramming that goes beyond DNA methylation, a dynamic interplay that involves histone modifications, non-coding RNAs, transposable elements et al., as well as the potential input of the various types of 'hereditary' epigenetic information in the gametes - a game that has started before the fertilization.

  20. Sex, Sexuality, Sexting, and SexEd: Adolescents and the Media

    Science.gov (United States)

    Brown, Jane D.; Keller, Sarah; Stern, Susannah

    2009-01-01

    The traditional media (television, radio, movies, magazines) and new, digital media (the Internet, Social Networking Sites such as Facebook and Myspace, and cell phones) have become important sex educators for adolescents. Adolescents in the United States spend six to seven hours a day with some form of media, often using more than one kind…

  1. Sex and Prevention Concerns for Positive People

    Science.gov (United States)

    ... with any comments or concerns. February 17, 2011 Sex and prevention concerns for positive people Facebook Twitter ... partner, and vice versa. The reality of safer sex You put yourself at risk for infections through ...

  2. 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.

  3. The Teacher and Sex Role Stereotyping

    Science.gov (United States)

    Juhasz, Anne McCreary

    1974-01-01

    In this article, selected research findings are presented on sex role learning, sex role stereotyping, in general and in the school setting, the effect of such stereotyping on the student, and some suggestions for the teacher. (Author/JA)

  4. 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

  5. Sex differences in intracranial arterial bifurcations

    DEFF Research Database (Denmark)

    Lindekleiv, Haakon M; Valen-Sendstad, Kristian; Morgan, Michael K

    2010-01-01

    . The female preponderance is usually explained by systemic factors (hormonal influences and intrinsic wall weakness); however, the uneven sex distribution of intracranial aneurysms suggests a possible physiologic factor-a local sex difference in the intracranial arteries....

  6. SEX DETERMINATION FROM FEMORAL HEAD DIAMETERS IN ...

    African Journals Online (AJOL)

    hi-tech

    2000-03-01

    Mar 1, 2000 ... In medico-legal cases where sophisticated methods of sex determination is lacking, these ... scientific methods(3). Using the visual method ... between the sexes and the values of the right and left femoral head diameters.

  7. Sexing the Brain: The Science and Pseudoscience of Sex Differences

    Directory of Open Access Journals (Sweden)

    Lesley J. Rogers

    2010-06-01

    Full Text Available A recent upsurge in unitary biological explanations for gender differences in behavior (i.e. that they are “hard-wired” in the genetic code, put forward not only in books written for a general audience but also in scientific papers, makes it important to examine the fallacies of these ideas. Such genetic and hormonal explanations of human behavior, formulated with little consideration of the influences of experience, and often without taking experience into account at all, are part of a new wave of genetic explanations for a broad range of human behavior, as explained in the paper. These ideas are far from new; moreover, they are pseudoscientific and are used for political influence under the guise of science. They are a conservative social force that maintains social and educational inequalities between women and men. This paper explains that causal explanations of differences between the sexes are of two completely different types: unitary (genetic determinist versus interactive explanations. The false reasoning used to support genetic determinist explanations of sex differences in behavior is discussed. To illustrate what biology really tells us about gender differentiation, the paper discusses the interactive roles of genetic, hormonal and environmental influences on the development of gender differences. These interactions are illustrated using two model biological systems (e.g. the intertwined influences of genes, sex hormones and experience on the development of sex differences in behavior in rats, and sex differences in neuronal connections in chickens. There is plenty of scientific evidence to show the complex interactive, and ever changing, influences of experience and genes that take place as an organism develops and throughout its life. Malleability of brain and behavior can be shown clearly using animal models, and the processes involved apply also to the development of brain and behavior in humans. We diminish our understanding

  8. 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....

  9. Sex work, immigration and social difference

    OpenAIRE

    Ham, Julie

    2017-01-01

    Public discourses around ‘migrant sex workers’ are often more confident about what migrant sex workers signify morally (i.e. vulnerability, criminality) but are less clear about who the ‘migrant’ is. This thesis interrogates the implications of the ‘migrant sex worker’ category based on semi-structured interviews with 65 immigrant, migrant and racialised women in sex work and two support staff in Melbourne, Australia and Vancouver, Canada during 2013–2014. Specifically, I employ an intersecti...

  10. Influence of plant size on female-biased sex allocation in a single-flowered, nectarless herb

    Science.gov (United States)

    Xiong, Ying-Ze; Xie, Meng; Huang, Shuang-Quan

    2016-01-01

    Relative allocation to female and male function in hermaphroditic species often departs from strict equisexuality. Increased femaleness with plant size in animal-pollinated species has been proposed in theory and demonstrated in empirical studies. However, such size-dependent sex allocation (SDS) has not been observed in some insect-pollinated species, throwing doubt on the generalization of SDS, that large plants have decelerated male function investment. Himalayan mayapple Podophyllum hexandrum (Berberidaceae) produces a single terminal flower and no nectar, providing a simple system for studying SDS without the confounding effects of flower number and nectar production. To investigate the SDS in P. hexandrum, plant size, biomass of floral organs (stamens, pistils and petals) and gamete production (pollen and ovule number) were measured in four populations in Yunnan Province, northwest China. Isometric allocation to female and male function with plant size was found in two populations, but the prediction of SDS was supported in the other two populations. Using pollen and ovule production as the allocation currency, allocation to female and male function was isometric in all studied populations. Resources allocated to attractive (petals) and sexual (pistils and stamens) structures did not show a significantly disproportionate increase with plant size in three of the four studied populations. The general pattern of isometric allocation to female and male function and to attractive and sexual structures could be attributed to the species being capable of automatic self-pollination, related to low pollen loss, minor deleterious effect of selfing and low importance of attractive structures. However, in further studies, careful consideration should be given to the different currencies used to estimate sex allocation. PMID:26602988

  11. Analyzing Medical Students' Definitions of Sex

    Science.gov (United States)

    Talley, Heather; Cho, Janice; Strassberg, Donald S.; Rullo, Jordan E.

    2016-01-01

    An inaccurate definition of what constitutes sex can negatively impact the sexual health and wellbeing of patients. This study aimed to determine which behaviors medical students consider to be sex. Survey questions about various sexual behaviors were administered to medical students. All participants agreed that penile-vaginal penetration is sex.…

  12. More on the New Sex Education.

    Science.gov (United States)

    Kasun, Jacqueline

    1980-01-01

    Replies to Paul V. Crosbie's criticisms. Argues that: reports of teenage sexuality and pregnancy are exaggerated; sex education programs encourage acceptance of every form of sexual expression; parents cannot always control their children's participation in sex education; and teachers are not equipped to teach sex education in a neutral fashion.…

  13. Sex Ideologies in China: Examining Interprovince Differences.

    Science.gov (United States)

    Hu, Yang

    2016-01-01

    In recent decades, premarital sex, extramarital sex, and homosexuality have become increasingly visible in China, leading scholars to claim that a national "sex revolution" is under way. However, China's internal sociocultural diversity calls this nation-level generalization into question. How do sex ideologies vary across China's distinct provinces? To what extent are interprovince variations in sex ideologies associated with distinct macrolevel social factors in China? In this research, data from the 2010 China General Social Survey and the 2011 Chinese Statistics Yearbook were analyzed using multilevel models to test four contending theories of interprovince differences in sex ideologies in China: modernization, Westernization, deindustrialization, and the "rice theory." The modernization theory was unsupported by the results, as socioeconomic development is not significantly associated with sex ideologies. Higher levels of deindustrialization and Westernization were associated with less traditional sex ideologies, but the strength of association varied across the domains of premarital sex, extramarital sex, and homosexuality. The rice theory was consistently supported, as the distinction between rice and wheat agriculture explained up to 30% of the province-level variance in sex ideologies. The findings underline the roles of both long-standing geographic differences and recent social changes in shaping China's ideational landscape of sex.

  14. Sex Role Development in Early Adolescence.

    Science.gov (United States)

    Wittig, Michele Andrisin

    1983-01-01

    Research involving adolescent identification with and development of sex roles is reviewed in the areas of cognitive skills and personality traits, theories of sex role development, and minority group adolescent sex role development. Emerging issues and educational implications in these areas are discussed. (CJ)

  15. Sexual Stratification and Sex-Role Socialization

    Science.gov (United States)

    VanFossen, Beth Ensiminger

    1977-01-01

    Data on sex-role values of a sample of college women are examined to ascertain the effect of family structure, social class, and religion on sex-role values, and to support a structural theory of sex-role socialization. (Author)

  16. The Promise of Single-Sex Classes

    Science.gov (United States)

    Stotsky, Sandra

    2012-01-01

    Despite the enthusiasm and the absence of definitive research on the pros and cons of single-sex classes, a 2011 article in Science, titled "The Pseudoscience of Single-Sex Schooling," by a new organization called American Council for CoEducational Schooling (ACCES) came out with the astonishing conclusion that single-sex education is…

  17. The Advantages of Single-Sex Education

    Science.gov (United States)

    Hughes, Teresa A.

    2006-01-01

    Traditionally, single-sex education has been provided in the form of private schooling. Title IX regulations have loosened as a result of the No Child Left Behind Legislation; therefore, public school districts now have the legal right to create single-sex classes or single-sex schools if they deem it to be in the best interest of their students.…

  18. Sex Differences in Assertiveness in College Students

    Science.gov (United States)

    Stebbins, Charles; And Others

    1977-01-01

    Validates the "College Self-Expression Scale." Shows that females are significantly more assertive, and that in one of the criterion situations each sex was significantly more assertive toward members of the same sex than members of the opposite sex. (RL)

  19. HIV and safe, healthy sex.

    Science.gov (United States)

    1997-01-01

    If a woman wants to become pregnant, how can she reduce her risk of HIV and other sexually transmitted infections? When a young man is growing up and worried about his future, how can you expect him to be concerned about HIV? Many HIV prevention projects focus on HIV and other sexually transmitted infections without considering people's broader reproductive and sexual health concerns. HIV prevention depends on people being able to make choices about their sexual behavior. This means understanding how their bodies work, knowing what choices are available to them, and having the confidence and skills to discuss and make changes in their sexual and reproductive lives. HIV educators, family planning workers, youth counselors, and others need to be able to respond to a range of questions and concerns in a sensitive and supportive way. This special, double issue of AIDS Action provides basic facts about the reproductive system, fertility, sexually transmitted infections and contraception, and looks at the links between HIV, sex, and reproduction. Talking about sex can be difficult. Sex is a private matter and people often feel embarrassed talking about it. This issue also contains tips for communication and activities to find out what people know already and help them learn. You may find that not everything in this issue is necessary for the people you are working with. This is a 'pick and mix' issue for you to pick out what is useful, adapting it if you wish. full text

  20. MODERN TEENAGER (HIGHLANDER AND SEX

    Directory of Open Access Journals (Sweden)

    Oksana Fedyk

    2015-04-01

    Full Text Available The age at which you can start or be sexually active - a very interesting question, which concerned not only parents, but also psychologists. Usually, you can not answer the question of when and to whom to start having sex. However, there are certain statistics that the average age of sexual debut in adolescents - is 15 years for girls and 14 for boys. Now we are talking about European society, about what is happening in Ukraine, particularly in mountainous areas. The fact that the willingness in principle to sexual intercourse is associated with physiological aspects. There is a notion in sexology - sexual constitution. There are several factors play a role, of course, one of which is constitutional, but not always, psychological maturity and sexual constitution, rather, because of the need for sexual constitution in holding intercourse can match. That is, some teens may be physiologically ready for sexual intercourse at 12-13 years, but the question arises: Are they psychologically? And probably we can not give a definite answer to this question, because curiosity taboo in society, which in the majority rejects teen sex, pushing them into early sexual relations. Nevertheless, probably still age readiness and psychological and physiological - is 18-19 years if we are talking about teen sex.

  1. [Does really sex addiction exist?].

    Science.gov (United States)

    Echeburúa, Enrique

    2012-01-01

    Hypersexual Disorder has been proposed as a new psychiatric disorder for DSM-V, characterized by an increased frequency and intensity of sexually motivated fantasies, arousal, urges, and enacted behavior in association with an impulsivity component. Excessive appetitive and consummatory behaviors, including hypersexuality, can become a non-chemical addiction. Sexual addiction afflicts people having paraphilic or nonparaphilic behaviors associated with progressive risk-taking sexual behaviors, escalation or progression of sexual behaviors (tolerance), loss of control and significant adverse psychosocial consequences, such as unplanned pregnancy, pair-bond dysfunction, marital separation, financial problems and sexually transmitted diseases including HIV. The most common behaviors involved in sexual addiction are fantasy sex, compulsive masturbation, pornography, cybersex, voyeuristic sex, anonymous sex and multiple sexual partners. These behaviors are intended to reduce anxiety and other dysphoric affects (e.g., shame and depression). Axis I psychiatric diagnosis, especially mood disorders, psychoactive substance abuse disorders and attention deficit hyperactivity disorders, are common comorbid disorders with sexual addiction. There are significant gaps in the current scientific knowledge base regarding the clinical course, development risk factors and family history and data on women with sexual addiction are lacking.

  2. Sex

    OpenAIRE

    Webber, Jonathan

    2009-01-01

    The sexual domain is unified only by the phenomenal quality of the occurrence of the desires, activities, and pleasures it includes. There is no conceptual restriction on the range of intentional objects those desires, activities, and pleasures can take. Neither is there good conceptual reason to privilege any class of them as paradigmatic. Since the quality unifying the sexual is not morally significant, the morality of sexuality is no different from morality in general. The view that partic...

  3. 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

  4. A Theoretical Analysis of Sex Differences In Same-Sex Friendships.

    Science.gov (United States)

    Barth, Robert J.; Kinder, Bill N.

    1988-01-01

    Investigates sex differences in same-sex friendships of 312 undergraduate students in terms of the intersection and social penetration model of relationship development, and Bem's theory of sex role orientation. Finds significant sex-related differences in depth, duration, and involvement. (FMW)

  5. Sex Education and Sex Stereotypes: Theory and Practice. Working Paper No. 198.

    Science.gov (United States)

    Stubbs, Margaret L.

    This paper presents an explanation of practitioners' reactions to sex equitable sex education. Several constraints can prohibit practitioners from engaging in sex equitable sex education: (1) lack of community support; (2) lack of expertise in human sexuality education; (3) vagueness of school committee views; and (4) lack of answers to logistical…

  6. Sex and the Filipino adolescent.

    Science.gov (United States)

    Anigan, G

    1979-01-01

    Very little is known about Filipino adolescents. Professional opinion varies enormously as to what is to be considered normal and abnormal. 1 aspect of adolescence which is agreed upon is that it is a period of great change. What brings on puberty is a controversial topic. Nutrition and genetic inheritance have been found to affect the age at which menstruation begins. Environment plays a large role in emotional and social growth. Filipino sex education is rather haphazard. A study of over 5000 adolescents in 1972-73 showed that sexual information was gained principally from pornographic literature, movies, television and friends. Boys also watched strip-tease acts and went to houses of prostitution. 2/3 of males and 3/4 of females had had crushes, while over 1/2 of both sexes had "gone steady" by age 16. Boys fell in love more often and less seriously than did girls. Girls generally have more adjustment problems in adolescence than do boys. Among Filipino adolescents, dating is the top ranking sex-related problem. Both sexes are concerned with what is the proper behavior in dating. Dating is an erotic as well as a social experience for Filipino adolescents. Premarital sexual activity is now receiving more tolerance. Urban males are less concerned with the virginity of their brides, but adults are still intolerant. Perhaps the present generation of adolescents is the harbinger of a new sexual morality. Fertility rates for 15-19 year olds have been declining since the 1960s. However, among adolescents with problems, pregnancy ranks high. Homosexuals are more visible in the Philippines now, as they are being more tolerated. Adolescent fertility is the last great challenge in the family planning field. Problems are unwillingness of counselors to participate in studies and a paucity of basic research. 3 studies are now being conducted in the Metro Manila area. Peer counseling and multiservice centers which provide relative anonymity are 2 approaches which shoul d be

  7. Sex differences in same-sex direct aggression and sociosexuality: the role of risky impulsivity.

    Science.gov (United States)

    Cross, Catharine P

    2010-12-23

    Sex differences in same-sex direct aggression and sociosexuality are among the most robust in the literature. The present article evaluated the hypothesis that both can be explained by a sex difference in the willingness to take impulsive risks. Self-report data were gathered from 3,775 respondents (1,514 female) on same-sex aggression, sociosexuality, and risky impulsivity. Risky impulsivity was higher for men than for women (d = .34) and path analysis showed it to be a common cause of same-sex aggression and sociosexuality for both sexes. However, it did not completely mediate the sex differences in same-sex aggression and sociosexuality. The results suggest that same-sex aggression and sociosexual behavior share a common psychological mechanism, but that fully explaining sex differences in aggression requires a more sensitive assay of impulsive risk and a consideration of dyadic processes.

  8. Sex Differences in Same-Sex Direct Aggression and Sociosexuality: The Role of Risky Impulsivity

    Directory of Open Access Journals (Sweden)

    Catharine P. Cross

    2010-10-01

    Full Text Available Sex differences in same-sex direct aggression and sociosexuality are among the most robust in the literature. The present article evaluated the hypothesis that both can be explained by a sex difference in the willingness to take impulsive risks. Self-report data were gathered from 3,775 respondents (1,514 female on same-sex aggression, sociosexuality, and risky impulsivity. Risky impulsivity was higher for men than for women (d = .34 and path analysis showed it to be a common cause of same-sex aggression and sociosexuality for both sexes. However, it did not completely mediate the sex differences in same-sex aggression and sociosexuality. The results suggest that same-sex aggression and sociosexual behavior share a common psychological mechanism, but that fully explaining sex differences in aggression requires a more sensitive assay of impulsive risk and a consideration of dyadic processes.

  9. Governing sex work in the city

    OpenAIRE

    Laing, Mary; Cook, Ian

    2014-01-01

    Sex work is often constructed as an urban "problem". As a result, sex workers, clients and the spaces in which people buy or sell sex are frequently the subject of intervention from those governing cities. This paper considers the ways in which problems and solutions are framed in the wider governance of sex work in cities in the global north. It draws on a range of academic literature to show how the urban governance of sex work takes relational and territorial forms. Governance is relationa...

  10. Screening Sex: revelando e dissimulando o sexo Screening Sex

    Directory of Open Access Journals (Sweden)

    Linda Williams

    2012-06-01

    Full Text Available Neste texto, procura-se contar a história da exibição do sexo em filmes majoritariamente produzidos nos Estados Unidos no período de quase um século. Ao se perguntar quando, porque e como os Estados Unidos se transformaram de uma cultura que não exibia o sexo em uma que o exibe, a autora insiste no duplo significado do verbo screen (tanto como uma revelação quanto uma dissimulação. Exibir é revelar em uma tela. Mas um segundo e igualmente importante significado, como diz o dicionário é "proteger ou esconder atrás de uma tela". Os filmes tanto revelam como escondem. O artigo analisa a forma como mudanças sociais ocorridas nos Estados Unidos, como, por exemplo, a Revolução sexual dos anos 60 e novas visões a respeito da sexualidade, possibilitaram novas maneiras de representação do sexo no cinema, reorganizando a relação entre o público e o privado. O artigo se pergunta também sobre como nossos corpos e sentidos reagem ao encontro com o sexo na tela, introduzindo a ideia de "saber carnal" (carnal knowledge.In this paper, we try to tell the history of the exhibition of sex in movies mainly produced in the United States in almost a century. Asking when, why and how the United States became - from a culture that did not exhibit sex - into a culture that exhibits it, the author insists in the double sense of the verb to screen (as both a revelation and a dissimulation. To exhibit is to reveal in a screen. But another, and important, sense, as says the dictionary, is "to protect or hide behind a screen". Movies show as well as they reveal. The paper analyzes the way social change in the United States, for example the sexual revolution of the sixties and new views on sexuality allowed new ways of representing sex in the movies, creating a new relation between public and private. The paper also asks how our bodies and senses react to sex in the screen, introducing the idea of "carnal knowledge".

  11. Sex tourism among Chinese men who have sex with men: a cross-sectional observational study.

    OpenAIRE

    Mao, J; Tang, W; Liu, C; Wong, NS; Tang, S; Wei, C; Tucker, JD

    2018-01-01

    Sex tourism among men who have sex with men (MSM) may exacerbate transmission of HIV and other sexually transmitted infections (STIs). Sex tourism is defined as purchasing sex with gifts or money outside of one's hometown. Our objective was to characterize the frequency, socio-demographic characteristics, and sexual risk behaviors among Chinese MSM sex tourists. An online, cross-sectional survey for high-risk MSM throughout China was conducted in November 2015 covering sociodemographic charac...

  12. Same sex marriage and the perceived assault on opposite sex marriage.

    Science.gov (United States)

    Dinno, Alexis; Whitney, Chelsea

    2013-01-01

    Marriage benefits both individuals and societies, and is a fundamental determinant of health. Until recently same sex couples have been excluded from legally recognized marriage in the United States. Recent debate around legalization of same sex marriage has highlighted for anti-same sex marriage advocates and policy makers a concern that allowing same sex couples to marry will lead to a decrease in opposite sex marriages. Our objective is to model state trends in opposite sex marriage rates by implementation of same sex marriages and other same sex unions. Marriage data were obtained for all fifty states plus the District of Columbia from 1989 through 2009. As these marriage rates are non-stationary, a generalized error correction model was used to estimate long run and short run effects of same sex marriages and strong and weak same sex unions on rates of opposite sex marriage. We found that there were no significant long-run or short run effects of same sex marriages or of strong or weak same sex unions on rates of opposite sex marriage. A deleterious effect on rates of opposite sex marriage has been argued to be a motivating factor for both the withholding and the elimination of existing rights of same sex couples to marry by policy makers-including presiding justices of current litigation over the rights of same sex couples to legally marry. Such claims do not appear credible in the face of the existing evidence, and we conclude that rates of opposite sex marriages are not affected by legalization of same sex civil unions or same sex marriages.

  13. Same Sex Marriage and the Perceived Assault on Opposite Sex Marriage

    Science.gov (United States)

    Dinno, Alexis; Whitney, Chelsea

    2013-01-01

    Background Marriage benefits both individuals and societies, and is a fundamental determinant of health. Until recently same sex couples have been excluded from legally recognized marriage in the United States. Recent debate around legalization of same sex marriage has highlighted for anti-same sex marriage advocates and policy makers a concern that allowing same sex couples to marry will lead to a decrease in opposite sex marriages. Our objective is to model state trends in opposite sex marriage rates by implementation of same sex marriages and other same sex unions. Methods and Findings Marriage data were obtained for all fifty states plus the District of Columbia from 1989 through 2009. As these marriage rates are non-stationary, a generalized error correction model was used to estimate long run and short run effects of same sex marriages and strong and weak same sex unions on rates of opposite sex marriage. We found that there were no significant long-run or short run effects of same sex marriages or of strong or weak same sex unions on rates of opposite sex marriage. Conclusion A deleterious effect on rates of opposite sex marriage has been argued to be a motivating factor for both the withholding and the elimination of existing rights of same sex couples to marry by policy makers–including presiding justices of current litigation over the rights of same sex couples to legally marry. Such claims do not appear credible in the face of the existing evidence, and we conclude that rates of opposite sex marriages are not affected by legalization of same sex civil unions or same sex marriages. PMID:23776536

  14. Sex Differences in Human and Animal Toxicology.

    Science.gov (United States)

    Gochfeld, Michael

    2017-01-01

    Sex, the states of being female or male, potentially interacts with all xenobiotic exposures, both inadvertent and deliberate, and influences their toxicokinetics (TK), toxicodynamics, and outcomes. Sex differences occur in behavior, exposure, anatomy, physiology, biochemistry, and genetics, accounting for female-male differences in responses to environmental chemicals, diet, and pharmaceuticals, including adverse drug reactions (ADRs). Often viewed as an annoying confounder, researchers have studied only one sex, adjusted for sex, or ignored it. Occupational epidemiology, the basis for understanding many toxic effects in humans, usually excluded women. Likewise, Food and Drug Administration rules excluded women of childbearing age from drug studies for many years. Aside from sex-specific organs, sex differences and sex × age interactions occur for a wide range of disease states as well as hormone-influenced conditions and drug distribution. Women have more ADRs than men; the classic sex hormone paradigm (gonadectomy and replacement) reveals significant interaction of sex and TK including absorption, distribution, metabolisms, and elimination. Studies should be designed to detect sex differences, describe the mechanisms, and interpret these in a broad social, clinical, and evolutionary context with phenomena that do not differ. Sex matters, but how much of a difference is needed to matter remains challenging.

  15. Sex differences in heritability of BMI

    DEFF Research Database (Denmark)

    Schousboe, Karoline; Willemsen, Gonneke; Kyvik, Kirsten O

    2003-01-01

    pairs (including opposite sex pairs) aged 20-29 and 30-39 from eight different twin registries participating in the GenomEUtwin project. Quantitative genetic analyses were conducted and sex differences were explored. Variation in BMI was greater for women than for men, and in both sexes was primarily...... explained by additive genetic variance in all countries. Sex differences in the variance components were consistently significant. Results from analyses of opposite sex pairs also showed evidence of sex-specific genetic effects suggesting there may be some differences between men and women in the genetic...... factors that influence variation in BMI. These results encourage the continued search for genes of importance to the body composition and the development of obesity. Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects....

  16. Sex work among men who have sex with men and transgender women in Bogotá.

    Science.gov (United States)

    Bianchi, Fernanda T; Reisen, Carol A; Zea, Maria Cecilia; Vidal-Ortiz, Salvador; Gonzales, Felisa A; Betancourt, Fabián; Aguilar, Marcela; Poppen, Paul J

    2014-11-01

    This qualitative study examined sex work among internally displaced male and transgender female sex workers in Bogotá, Colombia. Internal displacement has occurred in Colombia as a result of decades of conflict among armed groups and has created large-scale migration from rural to urban areas. Informed by the polymorphous model of sex work, which posits that contextual conditions shape the experience of sex work, we examined three main research questions. The first dealt with how internal displacement was related to the initiation of sex work; the second concerned the effect of agency on sex worker satisfaction; and the third examined how sex work in this context was related to HIV and other risks. Life history interviews were conducted with 26 displaced individuals who had done sex work: 14 were men who have sex with men and 12 were transgender women (natal males). Findings revealed that many participants began doing sex work in the period immediately after displacement, because of a lack of money, housing, and social support. HIV risk was greater during this time due to limited knowledge of HIV and inexperience negotiating safer sex with clients. Other findings indicated that sex workers who exerted more control and choice in the circumstances of their work reported greater satisfaction. In addition, we found that although many sex workers insisted on condom use with clients, several noted that they would sometimes have unprotected sex for additional money. Specific characteristics affecting the experience of sex work among the transgender women were also discussed.

  17. Developmental expression of “germline”- and “sex determination”-related genes in the ctenophore Mnemiopsis leidyi

    Directory of Open Access Journals (Sweden)

    Adam M. Reitzel

    2016-08-01

    Full Text Available Abstract Background An essential developmental pathway in sexually reproducing animals is the specification of germ cells and the differentiation of mature gametes, sperm and oocytes. The “germline” genes vasa, nanos and piwi are commonly identified in primordial germ cells, suggesting a molecular signature for the germline throughout animals. However, these genes are also expressed in a diverse set of somatic stem cells throughout the animal kingdom leaving open significant questions for whether they are required for germline specification. Similarly, members of the Dmrt gene family are essential components regulating sex determination and differentiation in bilaterian animals, but the functions of these transcription factors, including potential roles in sex determination, in early diverging animals remain unknown. The phylogenetic position of ctenophores and the genome sequence of the lobate Mnemiopsis leidyi motivated us to determine the compliment of these gene families in this species and determine expression patterns during development. Results Our phylogenetic analyses of the vasa, piwi and nanos gene families show that Mnemiopsis has multiple genes in each family with multiple lineage-specific paralogs. Expression domains of Mnemiopsis nanos, vasa and piwi, during embryogenesis from fertilization to the cydippid stage, were diverse, with little overlapping expression and no or little expression in what we think are the germ cells or gametogenic regions. piwi paralogs in Mnemiopsis had distinct expression domains in the ectoderm during development. We observed overlapping expression domains in the apical organ and tentacle apparatus of the cydippid for a subset of “germline genes,” which are areas of high cell proliferation, suggesting that these genes are involved with “stem cell” specification and maintenance. Similarly, the five Dmrt genes show diverse non-overlapping expression domains, with no clear evidence for

  18. Sulfogalactosylglycerolipid is involved in human gamete interaction.

    Science.gov (United States)

    Weerachatyanukul, W; Rattanachaiyanont, M; Carmona, E; Furimsky, A; Mai, A; Shoushtarian, A; Sirichotiyakul, S; Ballakier, H; Leader, A; Tanphaichitr, N

    2001-12-01

    Recent results from our laboratory have revealed the role of sulfogalactosylglycerolipid (SGG) in mouse sperm-zona pellucida (ZP) binding. In this report, we demonstrated the presence of SGG in Percoll-gradient centrifuged (PGC) human sperm by high performance thin layer chromatography with orcinol and Azure A staining, specific for glycolipids and sulfolipids, respectively. SGG in human PGC sperm was quantified by its affinity to Azure A to be 12-15 mol% of sperm lipids. Indirect immunofluorescence revealed that SGG existed on both live and aldehyde fixed human sperm in the head region. Pretreatment of human PGC sperm with affinity purified antiSGG Fab markedly inhibited sperm binding to the ZP in a concentration dependent manner, without any changes in the spontaneous acrosome rate or sperm motility parameters. Fluorescently labeled SGG liposomes also bound uniformly to isolated human ZP, while fluorescently labeled galactosylglycerolipid (GG, SGG's parental lipid) or phosphatidylserine (PS, negatively charged like SGG) liposomes did not. All of these results suggested the role of human sperm SGG in ZP binding. Copyright 2001 Wiley-Liss, Inc.

  19. Genetic sex determination and extinction.

    Science.gov (United States)

    Hedrick, Philip W; Gadau, Jürgen; Page, Robert E

    2006-02-01

    Genetic factors can affect the probability of extinction either by increasing the effect of detrimental variants or by decreasing the potential for future adaptive responses. In a recent paper, Zayed and Packer demonstrate that low variation at a specific locus, the complementary sex determination (csd) locus in Hymenoptera (ants, bees and wasps), can result in a sharply increased probability of extinction. Their findings illustrate situations in which there is a feedback process between decreased genetic variation at the csd locus owing to genetic drift and decreased population growth, resulting in an extreme type of extinction vortex for these ecologically important organisms.

  20. Men who advertise for sex.

    Science.gov (United States)

    Lumby, M E

    1978-01-01

    This content analysis of 1,111 paid ads in the Advocate identifies 17 self-descriptive categories in the "Personals" (PER) and "Models, Masseurs, and Escorts" (MME) sections of the "Trader Dick" supplement. Advertisers place primary emphases on sex and masculinity. Among MME, youthfulness, handsomeness, and sexiness are important, promoting versatility in place of specificity when mentioning sexual acts. PER advertisers, however, indicate concerns about age, race, and finding lovers. They also detail specific sexual interests and reject a variety of unacceptable behaviors.

  1. Sex differences in human epilepsy.

    Science.gov (United States)

    Savic, Ivanka

    2014-09-01

    In the majority of neuropsychiatric conditions, marked gender-based differences have been found in the epidemiology, clinical manifestations, and therapy of disease. Emerging data suggest that gender differences exist also in the epidemiology, and pathophysiology of epilepsy. The present review summarizes the current information regarding gender and epilepsy. These differences are regarded from the perspective of innate sex differences in cerebral morphology, structural and functional connections, and assuming that these differences may render men and women differently vulnerable to epileptogenicity. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Changes in steroid profiles of the blue mussel Mytilus trossulus as a function of season, stage of gametogenesis, sex, tissue and mussel bed depth.

    Science.gov (United States)

    Smolarz, Katarzyna; Zabrzańska, Sandra; Konieczna, Lucyna; Hallmann, Anna

    2018-04-01

    This paper describes changes in the content of free steroid hormones e.g. testosterone (T), estradiol-17β (E2), estrone (E1) and estriol (E3) of Mytilus trossulus from the southern Baltic Sea as a function of season, stage of gametogenesis, sex, tissue (gonadal and somatic) and depth. The highest levels of T, E2, E1 and E3 were found in mussels sampled in spring and summer while the lowest levels were found in winter. This pattern was stable and was seen in both sexes and tissues in mussels from both mussel beds. The spring and summer peaks in steroid levels (SL) coincided with advanced levels of gametogenesis (the highest gonadal index, GI) of our model species. But, the lowest GI (autumn) and the lowest steroids content (winter) did not overlap. Instead, water temperature increase was followed by increase of SL and vice versa. This suggests that steroids may not be actively involved in the early stages of gamete development and does not preclude them from potentially being involved as endogenous modulators in the final stages of reproduction (e.g. spawning). Hence, observed fluctuations in SL in our model species are unlikely to be caused by reproductive cycle but are rather of unknown nature, likely linked with environmental conditions. Sex-related differences in steroid content included estrogen domination in females and androgen domination in males. A trend towards higher level of steroids in gills than in gonads was found, supporting the hypothesis about an exogenous origin of steroids in bivalves. However, based on the present results, we cannot exclude the possibility that these steroids have both an endogenous and exogenous origin. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Sex-Role Portrayals of Selected Female Television Characters.

    Science.gov (United States)

    Goff, David H.; And Others

    1980-01-01

    Examines the relationship between both the sex-role and the sex of viewers and viewer perception of the sex-role depicted by five female characters in prime-time television programs. Perception of character sex-role was significantly related to subject sex-role, yet unrelated to subject sex or gender. (MER)

  4. Technology, normalisation and male sex work.

    Science.gov (United States)

    MacPhail, Catherine; Scott, John; Minichiello, Victor

    2015-01-01

    Technological change, particularly the growth of the Internet and smart phones, has increased the visibility of male escorts, expanded their client base and diversified the range of venues in which male sex work can take place. Specifically, the Internet has relocated some forms of male sex work away from the street and thereby increased market reach, visibility and access and the scope of sex work advertising. Using the online profiles of 257 male sex workers drawn from six of the largest websites advertising male sexual services in Australia, the role of the Internet in facilitating the normalisation of male sex work is discussed. Specifically we examine how engagement with the sex industry has been reconstituted in term of better informed consumer-seller decisions for both clients and sex workers. Rather than being seen as a 'deviant' activity, understood in terms of pathology or criminal activity, male sex work is increasingly presented as an everyday commodity in the market place. In this context, the management of risks associated with sex work has shifted from formalised social control to more informal practices conducted among online communities of clients and sex workers. We discuss the implications for health, legal and welfare responses within an empowerment paradigm.

  5. Searching for the Advantages of Virus Sex

    Science.gov (United States)

    Turner, Paul E.

    2003-02-01

    Sex (genetic exchange) is a nearly universal phenomenon in biological populations. But this is surprising given the costs associated with sex. For example, sex tends to break apart co-adapted genes, and sex causes a female to inefficiently contribute only half the genes to her offspring. Why then did sex evolve? One famous model poses that sex evolved to combat Muller's ratchet, the mutational load that accrues when harmful mutations drift to high frequencies in populations of small size. In contrast, the Fisher-Muller Hypothesis predicts that sex evolved to promote genetic variation that speeds adaptation in novel environments. Sexual mechanisms occur in viruses, which feature high rates of deleterious mutation and frequent exposure to novel or changing environments. Thus, confirmation of one or both hypotheses would shed light on the selective advantages of virus sex. Experimental evolution has been used to test these classic models in the RNA bacteriophage φ6, a virus that experiences sex via reassortment of its chromosomal segments. Empirical data suggest that sex might have originated in φ6 to assist in purging deleterious mutations from the genome. However, results do not support the idea that sex evolved because it provides beneficial variation in novel environments. Rather, experiments show that too much sex can be bad for φ6 promiscuity allows selfish viruses to evolve and spread their inferior genes to subsequent generations. Here I discuss various explanations for the evolution of segmentation in RNA viruses, and the added cost of sex when large numbers of viruses co-infect the same cell.

  6. Bacterial sex in dental plaque.

    Science.gov (United States)

    Olsen, Ingar; Tribble, Gena D; Fiehn, Nils-Erik; Wang, Bing-Yan

    2013-01-01

    Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

  7. Bacterial sex in dental plaque

    Directory of Open Access Journals (Sweden)

    Ingar Olsen

    2013-06-01

    Full Text Available Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

  8. Sex differences in addictive disorders.

    Science.gov (United States)

    Fattore, Liana; Melis, Miriam; Fadda, Paola; Fratta, Walter

    2014-08-01

    Gender-dependent differences in the rate of initiation and frequency of misuse of addicting drugs have been widely described. Yet, men and women also differ in their propensity to become addicted to other rewarding stimuli (e.g., sex, food) or activities (e.g., gambling, exercising). The goal of the present review is to summarize current evidence for gender differences not only in drug addiction, but also in other forms of addictive behaviours. Thus, we first reviewed studies showing gender-dependent differences in drug addiction, food addiction, compulsive sexual activity, pathological gambling, Internet addiction and physical exercise addiction. Potential risk factors and underlying brain mechanisms are also examined, with particular emphasis given to the role of sex hormones in modulating addictive behaviours. Investigations on factors allowing the pursuit of non-drug rewards to become pathological in men and women are crucial for designing gender-appropriate treatments of both substance and non-substance addictions. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Why sex hormones matter for neuroscience: A very short review on sex, sex hormones, and functional brain asymmetries.

    Science.gov (United States)

    Hausmann, Markus

    2017-01-02

    Biological sex and sex hormones are known to affect functional cerebral asymmetries (FCAs). Men are generally more lateralized than women. The effect size of this sex difference is small but robust. Some of the inconsistencies in the literature may be explained by sex-related hormonal differences. Most studies focusing on neuromodulatory properties of sex hormones on FCAs have investigated women during the menstrual cycle. Although contradictions exist, these studies have typically shown that levels of estradiol and/or progesterone correlate with the degree of FCAs, suggesting that sex differences in FCAs partially depend on hormonal state and day of testing. The results indicate that FCAs are not fixed but are hormone dependent, and as such they can dynamically change within relatively short periods throughout life. Many issues raised in this Mini-Review refer not only to FCAs but also to other aspects of functional brain organization, such as functional connectivity within and between the cerebral hemispheres. Our understanding of sex differences in brain and behavior as well as their clinical relevance will improve significantly if more studies routinely take sex and sex hormones into account. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Is Group Sex a Higher-Risk Setting for HIV and Other Sexually Transmitted Infections Compared With Dyadic Sex Among Men Who Have Sex With Men?

    NARCIS (Netherlands)

    van den Boom, Wijnand; Davidovich, Udi; Heuker, José; Lambers, Femke; Prins, Maria; Sandfort, Theo; Stolte, Ineke G.

    2016-01-01

    Group sex has been suggested as a potential high-risk setting for HIV and other sexually transmitted infections (STIs) among men who have sex with men (MSM). We investigated whether group sex is associated with lower condom use during anal sex and higher proportions of STIs compared with dyadic sex

  11. Sex differences and stress across the lifespan

    Science.gov (United States)

    Bale, Tracy L; Epperson, C Neill

    2015-01-01

    Sex differences in stress responses can be found at all stages of life and are related to both the organizational and activational effects of gonadal hormones and to genes on the sex chromosomes. As stress dysregulation is the most common feature across neuropsychiatric diseases, sex differences in how these pathways develop and mature may predict sex-specific periods of vulnerability to disruption and increased disease risk or resilience across the lifespan. The aging brain is also at risk to the effects of stress, where the rapid decline of gonadal hormones in women combined with cellular aging processes promote sex biases in stress dysregulation. In this Review, we discuss potential underlying mechanisms driving sex differences in stress responses and their relevance to disease. Although stress is involved in a much broader range of diseases than neuropsychiatric ones, we highlight here this area and its examples across the lifespan. PMID:26404716

  12. Sex differences and stress across the lifespan.

    Science.gov (United States)

    Bale, Tracy L; Epperson, C Neill

    2015-10-01

    Sex differences in stress responses can be found at all stages of life and are related to both the organizational and activational effects of gonadal hormones and to genes on the sex chromosomes. As stress dysregulation is the most common feature across neuropsychiatric diseases, sex differences in how these pathways develop and mature may predict sex-specific periods of vulnerability to disruption and increased disease risk or resilience across the lifespan. The aging brain is also at risk to the effects of stress, where the rapid decline of gonadal hormones in women combined with cellular aging processes promote sex biases in stress dysregulation. In this Review, we discuss potential underlying mechanisms driving sex differences in stress responses and their relevance to disease. Although stress is involved in a much broader range of diseases than neuropsychiatric ones, we highlight here this area and its examples across the lifespan.

  13. A reconfiguration of the sex trade

    DEFF Research Database (Denmark)

    Elmes, Jocelyn; Skovdal, Morten; Nhongo, Kundai

    2017-01-01

    a unique opportunity to study community perceptions of the impact of socio-economic upheaval on the sex trade. We conducted focus group discussions with 122 community members in rural eastern Zimbabwe in January-February 2009. Groups were homogeneous by gender and occupation and included female sex workers......Understanding the dynamic nature of sex work is important for explaining the course of HIV epidemics. While health and development interventions targeting sex workers may alter the dynamics of the sex trade in particular localities, little has been done to explore how large-scale social...... and structural changes, such as economic recessions–outside of the bounds of organizational intervention–may reconfigure social norms and attitudes with regards to sex work. Zimbabwe’s economic collapse in 2009, following a period (2000–2009) of economic decline, within a declining HIV epidemic, provides...

  14. Sex differences in heritability of neck Pain

    DEFF Research Database (Denmark)

    Fejer, René; Hartvigsen, Jan; Kyvik, Kirsten Ohm

    2006-01-01

    Experimental studies have suggested biological factors as a possible explanation for gender disparities in perception of pain. Recently, heritability of liability to neck pain (NP) has been found to be statistically significantly larger in women compared to men. However, no studies have been...... conducted to determine whether the sex differences in heritability of NP are due to sex-specific genetic factors. Data on lifetime prevalence of NP from a population-based cross-sectional survey of 33,794 Danish twins were collected and age-stratified univariate biometrical modeling using sex......-limitation models was performed based on 10,605 dizygotic (DZ) twins of opposite sex to estimate the qualitative sex differences. In a full sex-limitation model the genetic component in females were higher than in males, but the genetic and the shared environmental correlations were equal to what is normally...

  15. Patpong, entre sexe et commerce.

    Directory of Open Access Journals (Sweden)

    Sébastien Roux

    2010-03-01

    Full Text Available Le tourisme dit « sexuel » est aujourd’hui décrié comme une forme de tourisme international immoral, un dysfonctionnement grave de la mondialisation appelant une réaction politique contre « l’exploitation sexuelle » dont seraient victimes des millions de femmes et d’enfants. Pourtant, derrière l’apparente évidence du « tourisme sexuel » comme expression de sens commun, rares sont les enquêtes qui explicitent la réalité concrète des échanges prostitutionnels. En adoptant une démarche ethnographique, l’article décrit le fonctionnement de Patpong, un quartier rouge de Bangkok dédié à une clientèle internationale. Par la description des offres disponibles, des revenus générés, des codes et des pratiques, la complexité de l’espace réapparaît. Il s’agit de donner à voir la réalité des échanges pour interroger l’articulation entre commerce et sexualité. L’analyse ethnographique du tourisme sexuel permet ainsi de souligner la diversité des pratiques et de rappeler que les formes les plus visibles — et les plus commentées — d’échanges prostitutionnels éclipsent trop souvent une pluralité d’expériences qui participe pourtant au succès de ces ruelles mondialement connues. So-called sex tourism is condemned as an immoral form of international tourism, a serious failure of globalization requiring political action against the “sexual exploitation” suffered by millions of women and children. Yet behind the common and seemingly evident understanding of “sexual tourism,” few studies have focused on the actual reality of such relations. Based on an ethnographic study, this article presents the structure of Patpong, a red-light district of Bangkok dedicated to international tourism. First, the article aims to briefly present the historical development of Patpong. This peculiar space is intrinsically linked to sex tourism, as these world-renowned streets expanded since the mid-60s to

  16. Gender in Winterson's Sexing the Cherry

    OpenAIRE

    Kintzele, Paul

    2010-01-01

    In his article "Gender in Winterson's Sexing the Cherry" Paul Kintzele examines the ways in which Jeanette Winterson's 1989 novel explores and critiques aspects of gender and sexuality. While acknowledging the importance of the performance theory of gender that derives from the work of Judith Butler, Kintzele contends that such an approach must be complemented with a psychoanalytic approach that insists on a particular distinction between sex and gender. Although some scholars map the sex/gen...

  17. Sex tourism among Chinese men who have sex with men: a cross-sectional observational study.

    Science.gov (United States)

    Mao, Jessica; Tang, Weiming; Liu, Chuncheng; Wong, Ngai Sze; Tang, Songyuan; Wei, Chongyi; Tucker, Joseph D

    2018-03-02

    Sex tourism among men who have sex with men (MSM) may exacerbate transmission of HIV and other sexually transmitted infections (STIs). Sex tourism is defined as purchasing sex with gifts or money outside of one's hometown. Our objective was to characterize the frequency, socio-demographic characteristics, and sexual risk behaviors among Chinese MSM sex tourists. An online, cross-sectional survey for high-risk MSM throughout China was conducted in November 2015 covering sociodemographic characteristics, sexual risk behaviors, and sex tourism. Univariate and multivariable logistic regressions were performed to identify correlates of sex tourism. The mean MSM HIV prevalence of sex tourism journey origins and destinations were compared. Of 1189 MSM who completed the survey, 62 (5%) men identified as sex tourists; among these sex tourists, twenty (32%) traveled primarily to purchase sex and the remainder purchased sex while traveling for another purpose. There was minimal socio-demographic and behavioral difference between the two groups. In multivariable analyses, adjusting for age and income, sex tourism was correlated with high-risk sexual behaviors, higher income (aOR 4.44, 95%CI 1.77-11.18) and living with HIV (aOR 2.79, 95%CI 1.03-7.55). Sex tourism was more often from locations with lower to higher MSM HIV prevalence (mean = 4.47, SD = 2.01 versus mean = 6.86, SD = 5.24). MSM sex tourists were more likely to have risky sexual behaviors and travel to locations with a higher HIV prevalence. MSM sex tourists may be part of core groups that are disproportionately responsible for MSM HIV transmission. Enhanced surveillance and interventions tailored to MSM sex tourists should be considered.

  18. Same-Sex and Different-Sex Cohabiting Couple Relationship Stability.

    Science.gov (United States)

    Manning, Wendy D; Brown, Susan L; Stykes, J Bart

    2016-08-01

    Relationship stability is a key indicator of well-being, but most U.S.-based research has been limited to different-sex couples. The 2008 panel of the Survey of Income and Program Participation (SIPP) provides an untapped data resource to analyze relationship stability of same-sex cohabiting, different-sex cohabiting, and different-sex married couples (n = 5,701). The advantages of the SIPP data include the recent, nationally representative, and longitudinal data collection; a large sample of same-sex cohabitors; respondent and partner socioeconomic characteristics; and identification of a state-level indicator of a policy stating that marriage is between one man and one woman (i.e., DOMA). We tested competing hypotheses about the stability of same-sex versus different-sex cohabiting couples that were guided by incomplete institutionalization, minority stress, relationship investments, and couple homogamy perspectives (predicting that same-sex couples would be less stable) as well as economic resources (predicting that same-sex couples would be more stable). In fact, neither expectation was supported: results indicated that same-sex cohabiting couples typically experience levels of stability that are similar to those of different-sex cohabiting couples. We also found evidence of contextual effects: living in a state with a constitutional ban against same-sex marriage was significantly associated with higher levels of instability for same- and different-sex cohabiting couples. The level of stability in both same-sex and different-sex cohabiting couples is not on par with that of different-sex married couples. The findings contribute to a growing literature on health and well-being of same-sex couples and provide a broader understanding of family life.

  19. Interactive Effects of Culture and Sex Hormones on Sex Role Orientation

    Directory of Open Access Journals (Sweden)

    Belinda ePletzer

    2015-07-01

    Full Text Available Sex role orientation, i.e. a person’s masculinity or femininity, influences cognitive and emotional performance, like biological sex. While it is now widely accepted that sex differences are modulated by the hormonal status of female participants (menstrual cycle, hormonal contraceptive use, the question, whether hormonal status and sex hormones also modulate participants sex role orientation has hardly been addressed previously. The present study assessed sex role orientation and hormonal status as well as sex hormone levels in three samples of participants from two different cultures (Northern American, Middle European. Menstrual cycle phase did not affect participant’s masculinity or femininity, but had a significant impact on reference group. While women in their follicular phase (low levels of female sex hormones determined their masculinity and femininity in reference to men, women in their luteal phase (high levels of female sex hormones determined their masculinity and femininity in reference to women. Hormonal contraceptive users rated themselves as significantly more feminine and less masculine than naturally cycling women. Furthermore, the impact of biological sex on the factorial structure of sex role orientation as well as the relationship of estrogen to masculinity/femininity was modulated by culture. We conclude that culture and sex hormones interactively affect sex role orientation and hormonal status of participants should be controlled for when assessing masculinity and/or femininity.

  20. Romance tourism or female sex tourism?

    Science.gov (United States)

    Bauer, Irmgard L

    2014-01-01

    Love, sex and the female traveller: romance tourism or female sex tourism? The phenomenon of women travelling in search of relationships with local men in developing countries has been studied for the last 20 years. However, it appears little known in travel medicine. Relevant literature was found through PubMed, Science Direct, ProQuest and Google Scholar. The reference lists of selected articles identified further sources. Historical records of women travellers to far-away countries abound. Then, as now, women not only searched for the erotic 'other' but made romance and sex the purpose of their trip. Today, increasing numbers of women travel to destinations in developing countries where sex with local men is the main attraction. This pastime raises concerns not only for the women themselves but for the local men involved as well as their sex partners and the local communities. Although more research is necessary, comparing the criteria that describe men travelling for sex and relationships and women travelling for sex and relationships appears to suggest that there is very little difference between the two, regardless of what the pursuit is called. Women looking for sex with local men are sex tourists, too. Recognition of this fact needs to influence the pre and post travel care of female travellers. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Voices of Māori Sex Workers

    OpenAIRE

    Escaravage, Elise

    2016-01-01

    Aotearoa (New Zealand) is the only country in the world to have decriminalized sex work. The Prostitution Reform Act (PRA henceforth) was enacted in 2003 with the aim to safeguard the human rights of sex workers, and create a framework that is conducive to public health. Skeptics of this policy argue that the law reform was targeting indoor workers while the livelihood of street-based sex workers did not see significant improvements (Justice Acts, 2014). It is known that Māori sex workers are...

  2. Update on sexed semen technology in cattle.

    Science.gov (United States)

    Seidel, G E

    2014-05-01

    The technology in current use for sexing sperm represents remarkable feats of engineering. These flow cytometer/cell sorters can make over 30 000 consecutive evaluations of individual sperm each second for each nozzle and sort the sperm into three containers: X-sperm, Y-sperm and unsexable plus dead sperm. Even at these speeds it is not economical to package sperm at standard numbers per inseminate. However, with excellent management, pregnancy rates in cattle with 2 million sexed sperm per insemination dose are about 80% of those with conventional semen at normal sperm doses. This lowered fertility, in part due to damage to sperm during sorting, plus the extra cost of sexed semen limits the applications that are economically feasible. Even so, on the order of 2 million doses of bovine semen are sexed annually in the United States. The main application is for dairy heifers to have heifer calves, either for herd expansion or for sale as replacements, often for eventual export. Breeders of purebred cattle often use sexed semen for specific matings; thawing and then sexing frozen semen and immediately using the few resulting sexed sperm for in vitro fertilization is done with increasing frequency. Beef cattle producers are starting to use sexed semen to produce crossbred female replacements. Proprietary improvements in sperm sexing procedures, implemented in 2013, are claimed to improve fertility between 4 and 6 percentage points, or about 10%.

  3. Unusually dynamic sex roles in a fish.

    Science.gov (United States)

    Forsgren, Elisabet; Amundsen, Trond; Borg, Asa A; Bjelvenmark, Jens

    2004-06-03

    Sex roles are typically thought of as being fixed for a given species. In most animals males compete for females, whereas the females are more reluctant to mate. Therefore sexual selection usually acts most strongly on males. This is explained by males having a higher potential reproductive rate than females, leading to more males being sexually active (a male-biased operational sex ratio). However, what determines sex roles and the strength of sexual selection is a controversial and much debated question. In this large-scale field study, we show a striking temporal plasticity in the mating competition of a fish (two-spotted goby, Gobiusculus flavescens). Over the short breeding season fierce male-male competition and intensive courtship behaviour in males were replaced by female-female competition and actively courting females. Hence, sex role reversal occurred rapidly. This is the first time that a shift in sex roles has been shown in a vertebrate. The shift might be explained by a large decline in male abundance, strongly skewing the sex ratio towards females. Notably, the sex role reversal did not occur at an equal operational sex ratio, contrary to established sex role theory.

  4. Sex Trading Among Hazardously Drinking Jailed Women.

    Science.gov (United States)

    Schonbrun, Yael Chatav; Johnson, Jennifer; Anderson, Bradley J; Stein, Michael D

    For women involved in sex trading, both alcohol problems and passage through the criminal justice system are highly prevalent. This study is the first to conduct a focused examination of factors associated with sex trading among hazardously drinking, pretrial, jailed women. Cocaine use, social support for alcohol abstinence, and more days incarcerated in the 90 days leading up to the index incarceration were significantly associated with sex trading involvement among alcoholic women. Helping incarcerated alcoholic women reduce cocaine use and improve sober support networks during and following an incarceration may minimize sex trading after release.

  5. How Sex Selection Undermines Reproductive Autonomy.

    Science.gov (United States)

    Browne, Tamara Kayali

    2017-06-01

    Non-medical sex selection is premised on the notion that the sexes are not interchangeable. Studies of individuals who undergo sex selection for non-medical reasons, or who have a preference for a son or daughter, show that they assume their child will conform to the stereotypical roles and norms associated with their sex. However, the evidence currently available has not succeeded in showing that the gender traits and inclinations sought are caused by a "male brain" or a "female brain". Therefore, as far as we know, there is no biological reason why parents cannot have the kind of parenting experience they seek with a child of any sex. Yet gender essentialism, a set of unfounded assumptions about the sexes which pervade society and underpin sexism, prevents parents from realising this freedom. In other words, unfounded assumptions about gender constrain not only a child's autonomy, but also the parent's. To date, reproductive autonomy in relation to sex selection has predominantly been regarded merely as the freedom to choose the sex of one's child. This paper points to at least two interpretations of reproductive autonomy and argues that sex selection, by being premised on gender essentialism and/or the social pressure on parents to ensure their children conform to gender norms, undermines reproductive autonomy on both accounts.

  6. Decreasing Human Trafficking through Sex Work Decriminalization.

    Science.gov (United States)

    Albright, Erin; D'Adamo, Kate

    2017-01-01

    In order to decrease human trafficking, health care workers should support the full decriminalization of prostitution. Similar to trafficking in other forms of labor, preventing trafficking in the sex trade requires addressing the different forms of marginalization that create vulnerable communities. By removing punitive laws that prevent reporting of exploitation and abuse, decriminalization allows sex workers to work more safely, thereby reducing marginalization and vulnerability. Decriminalization can also help destigmatize sex work and help resist political, social, and cultural marginalization of sex workers. © 2017 American Medical Association. All Rights Reserved.

  7. 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).

  8. Female Sex Offenders: Public Awareness and Attributions.

    Science.gov (United States)

    Cain, Calli M; Anderson, Amy L

    2016-12-01

    Traditional gender roles, sex scripts, and the way female sex offenders are portrayed in the media may lead to misconceptions about who can commit sexual offenses. Sexual crimes by women may go unnoticed or unreported if there is a general lack of awareness that females commit these crimes. Data from the 2012 Nebraska Annual Social Indicators Survey were used to determine whether the public perceives women as capable sex offenders and the perceived causes of female sex offending. The traditional focus on male sex offenders by researchers, media, and politicians, in addition to gender stereotypes, introduces the possibility of group differences (e.g., between men and women) in perceptions of female sex offenders. Consequently, two secondary analyses were conducted that tested for group differences in both the public's perception of whether females can commit sex offenses and the explanations selected for why females sexually offend. The findings suggest that the public does perceive women as capable sex offenders, although there were group differences in the causal attributions for female sex offending.

  9. Beyond the 'safe sex' propaganda.

    Science.gov (United States)

    Hadzic, Maja; Khajehei, Marjan

    2010-01-01

    In this paper, we discuss sexual relationships among teenagers, the related issues, and suggest addressing the issues through effective education programs for both teenagers and their parents. We also discuss the main issues resulting from initiation of sexual relationship during adolescence such as unwanted pregnancy, maternal mortality, abortion, sexually transmitted diseases and damaged mental health. In addition, we highlight the lack of adequate sex education in teenagers and emphasize on the negative influence of TV programs and the harmful effects of dysfunctional families. Moreover, this article proposes equipping teenagers with knowledge that will help them understand not only physical but also emotional, social, and mental dynamics of sexual relationships. We believe that this approach would intervene much earlier in their life, help teenagers make healthy decision and minimize negative consequences of their personal choices.

  10. Sex and Intimacy after Stroke.

    Science.gov (United States)

    Kautz, Donald D; Van Horn, Elizabeth R

    The sequelae of a stroke can negatively affect sex and intimacy for survivors and their partners. This clinical article offers practical evidence-based recommendations for nurses to use in advising couples who may be experiencing sexual problems due to decreased desire, erectile dysfunction, vaginal dryness, paraparesis, pain, spasticity, fatigue, aphasia, concrete thinking, emotional lability, shame, embarrassment, fear, depression, or neurogenic bladder. Recent research and clinical articles show that intimacy and sexual concerns are often ignored by the rehabilitation team, yet research shows that couples want information to assist them to maintain their sexual relationships. Using the PLISSIT model to address sexual concerns, nurses can facilitate discussions to aid couples toward improved sexual function and quality of life.

  11. Sex Differences in Tibiocalcaneal Kinematics

    Directory of Open Access Journals (Sweden)

    Sinclair Jonathan

    2014-08-01

    Full Text Available Purpose. Female runners typically suffer more from chronic running injuries than age-matched males, although the exact biome-chanical mechanisms behind the increased susceptibility of female runners are unknown. This study aimed to compare sex differences in tibiocalcaneal kinematics during the stance phase of running. Methods. Twenty male and twenty female participants ran at 4.0 m · s–1. Tibiocalcaneal kinematics were measured using an eight-camera motion analysis system and compared using independent samples t tests. Results. Peak eversion and tibial internal rotation angles were shown to be significantly greater in female runners. Conclusions. based on these observations, it was determined that female runners may be at increased risk from chronic injury development in relation to excessive tibiocalcaneal motions in the coronal and transverse planes.

  12. Effects of sucrose and irradiance on germination and early gametophyte growth of the endangered tree fern Dicksonia sellowiana Hook (Dicksoniaceae Efeito da sacarose e irradiância na germinação e crescimento inicial do gametófito da samambaia arbórea Dicksonia sellowiana Hook (Dicksoniaceae em perigo de extinção

    Directory of Open Access Journals (Sweden)

    Gladys Daniela Rogge Renner

    2004-06-01

    Full Text Available It is an endangered tree fern that grows in mixed umbrophylus forests in the tropics. Sterilized spores were germinated at 25 ± 2ºC under a 16-hour photoperiod, in Dyer and MS medium supplemented with 0 to 5% sucrose. The germination was lower with the addition of sucrose. Dry mass was higher in 30-day-old gametophytes cultivated in Dyer medium with the addition of 3 to 5% of sucrose. The dry mass decreased in 30-day-old gametophytes cultivated in Dyer and MS media without sucrose and in MS medium with the addition of 4 or 5% of sucrose. The effect of different irradiance on the germination and early gametophyte development of D. sellowiana was analyzed in the autumn of 1998 (May until July. Conical flasks containing spores were kept over a period of 49 days in 50cm³ boxes covered with black shade netting, which gave 5, 20, 36 and 50% of irradiance. The lower mean germination time was observed for spores cultivated under 5% and 20% of irradiance. The highest chlorophyll content was recorded in gametophytes cultivated for 49 days under 20% and 5% of irradiance .The highest soluble sugar content was recorded in gametophytes cultivated under 5% and 20% of irradiance.Esta samambaia arbórea ameaçada de extinção ocorre na floresta ombrófila mista, nos trópicos. Esporos esterilizados germinaram a 25 ± 2ºC em fotoperíodo de 16 horas, em meios de Dyer e MS, acrescidos de 0 a 5% de sacarose. A massa seca foi maior em gametófitos de 30 dias de idade, cultivados em meio Dyer com adição de 3% a 5% de sacarose e em meio MS com adição de 2% de sacarose. A massa seca diminuiu em gametófitos crescidos em meios Dyer e MS na ausência de sacarose e em meio MS acrescido de 5% de sacarose. O efeito de diferentes irradiâncias na germinação e desenvolvimento inicial de gametófitos foi analisado no outono de 1998 (de maio a julho. Frascos cônicos contendo esporos foram mantidos durante 49 dias dentro de caixas de 50cm³ revestidas por telas que

  13. Reinventing Sex: The Construction of Realistic Definitions of Sex and Gender.

    Science.gov (United States)

    Small, Chanley M.

    1998-01-01

    Presents a set of criteria for constructing a fair and realistic understanding of sex. Recognizes the impact that science can have on social policies and values and recommends that the definitions of sex and gender be carefully crafted. (DDR)

  14. Television Sex Roles in the 1980s: Do Viewers' Sex and Sex Role Orientation Change the Picture?

    Science.gov (United States)

    Dambrot, Faye H.; And Others

    1988-01-01

    Investigates the viewer perceptions of female and male television characters as a result of viewer sex and sex role orientation, based on the responses of 677 young adults to the Personal Attributes Questionnaire (PAQ). Viewer gender had an impact on the rating of female characters. (FMW)

  15. BIOLOGICAL SEX, SEX-ROLE ORIENTATION, MASCULINE SEX-ROLE STRESS, DISSIMULATION AND SELF-REPORTED FEARS

    NARCIS (Netherlands)

    ARRINDELL, WA; KOLK, AM; PICKERSGILL, MJ; HAGEMAN, WJJM

    1993-01-01

    Given meta-analytic findings showing females to be generally more fearful than males on multi-dimensional self-report measures of fear, an empirical attempt was made to examine whether this outcome could be explained by psychological factors such as sex role orientation and masculine sex role

  16. Conclusions: Getting real about sex - embedding an embodied sex education in schools

    OpenAIRE

    Alldred, P; David, ME

    2007-01-01

    GET REAL ABOUT SEX: The Politics and Practice of Sex Education explores how cultural ideas about gender, sexuality and parenthood play out in the sex and relationship education classroom. It presents new material from a detailed study and analyses the struggle to raise the status of sex and relationship education against academic and market-driven priorities. It locates the dynamics of the classroom within those of the school and asks: What do the different parties in teaching and learning -...

  17. Correlates of Forced Sex Among Populations of Men Who Have Sex with Men in Thailand

    OpenAIRE

    Guadamuz, Thomas E.; Wimonsate, Wipas; Varangrat, Anchalee; Phanuphak, Praphan; Jommaroeng, Rapeepun; Mock, Philip A.; Tappero, Jordan W.; van Griensven, Frits

    2009-01-01

    Although forced sex is a correlate of HIV infection, its prevalence and associated risks are not well described among men who have sex with men (MSM) in developing-country settings. Between March and October 2005, we assessed the prevalence of forced sex and correlates among populations of MSM (this includes general MSM, male sex workers, and male-to-female transgender persons) in Thailand using a community-based sample. Participants were enrolled from venues around Bangkok, Chiangmai, and Ph...

  18. Molecular sex differences in human serum.

    Directory of Open Access Journals (Sweden)

    Jordan M Ramsey

    Full Text Available Sex is an important factor in the prevalence, incidence, progression, and response to treatment of many medical conditions, including autoimmune and cardiovascular diseases and psychiatric conditions. Identification of molecular differences between typical males and females can provide a valuable basis for exploring conditions differentially affected by sex.Using multiplexed immunoassays, we analyzed 174 serum molecules in 9 independent cohorts of typical individuals, comprising 196 males and 196 females. Sex differences in analyte levels were quantified using a meta-analysis approach and put into biological context using k-means to generate clusters of analytes with distinct biological functions. Natural sex differences were established in these analyte groups and these were applied to illustrate sexually dimorphic analyte expression in a cohort of 22 males and 22 females with Asperger syndrome. Reproducible sex differences were found in the levels of 77 analytes in serum of typical controls, and these comprised clusters of molecules enriched with distinct biological functions. Analytes involved in fatty acid oxidation/hormone regulation, immune cell growth and activation, and cell death were found at higher levels in females, and analytes involved in immune cell chemotaxis and other indistinct functions were higher in males. Comparison of these naturally occurring sex differences against a cohort of people with Asperger syndrome indicated that a cluster of analytes that had functions related to fatty acid oxidation/hormone regulation was associated with sex and the occurrence of this condition.Sex-specific molecular differences were detected in serum of typical controls and these were reproducible across independent cohorts. This study extends current knowledge of sex differences in biological functions involved in metabolism and immune function. Deviations from typical sex differences were found in a cluster of molecules in Asperger syndrome

  19. Conflict over condition-dependent sex allocation can lead to mixed sex-determination systems

    NARCIS (Netherlands)

    Kuijper, Bram; Pen, Ido

    Theory suggests that genetic conflicts drive turnovers between sex-determining mechanisms, yet these studies only apply to cases where sex allocation is independent of environment or condition. Here, we model parent-offspring conflict in the presence of condition-dependent sex allocation, where the

  20. 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

  1. "Dangerous Presumptions": How Single-Sex Schooling Reifies False Notions of Sex, Gender, and Sexuality

    Science.gov (United States)

    Jackson, Janna

    2010-01-01

    Due to the recent changes in federal regulations about gender equity in education in the USA, some policy makers have resurrected single-sex public education. Because single-sex schooling ignores the complexity of sex, gender, and sexuality, it sets up a "separate but equal" system that is anything but. Discounting the ways in which gender is…

  2. Do Sex Differences Define Gender-Related Individual Differences within the Sexes? Evidence from Three Studies.

    Science.gov (United States)

    Lippa, Richard

    1995-01-01

    Studied three different criteria of within-sex, gender-related individual differences taken from three studies. Data showed that items displaying large sex differences tended also to correlate most strongly with independent gender-related criteria within the sexes. Discusses assessment implications for gender-related and other group-related…

  3. Prenatal sex hormone effects on child and adult sex-typed behavior: methods and findings

    NARCIS (Netherlands)

    van de Beek, C.; Cohen-Bendahan, C.; Berenbaum, S.

    2005-01-01

    There is now good evidence that human sex-typed behavior is influenced by sex hormones that are present during prenatal development, confirming studies in other mammalian species. Most of the evidence comes from clinical populations, in which prenatal hormone exposure is atypical for a person's sex,

  4. Conflict over condition-dependent sex allocation can lead to mixed sex-determination systems

    NARCIS (Netherlands)

    Kuijper, Bram; Pen, Ido

    2014-01-01

    Theory suggests that genetic conflicts drive turnovers between sex-determining mechanisms, yet these studies only apply to cases where sex allocation is independent of environment or condition. Here, we model parent-offspring conflict in the presence of condition-dependent sex allocation, where the

  5. Development of Gender Discrimination: Effect of Sex-Typical and Sex-Atypical Toys.

    Science.gov (United States)

    Etaugh, Claire; Duits, Terri L.

    Toddlers (41 girls and 35 boys) between 18 and 37 months of age were given four gender discrimination tasks each consisting of 6 pairs of color drawings. Three of the tasks employed color drawings of preschool girls and boys holding either a sex-typical toy, a sex-atypical toy, or no toy. The fourth employed pictures of sex-typical masculine and…

  6. Alcohol and Sex Offending: What Do Child Sex Offenders Think about Drinking?

    Science.gov (United States)

    Monson, Candice M.; Jones, Lisa M.; Rivers, P. Clayton; Blum, Steven B.

    1998-01-01

    Examines relationships between general and sex-specific alcohol expectancies and drinking before offending with child sex offenders. Results show that sex-specific expectancies were the best predictor of the proportion of times the offenders reported drinking before offending. Highlights the importance of assessing expectancies related to…

  7. Do sex differences in rumination explain sex differences in depression?

    Science.gov (United States)

    Shors, Tracey J; Millon, Emma M; Chang, Han Yan M; Olson, Ryan L; Alderman, Brandon L

    2017-01-02

    It is generally accepted that women tend to ruminate more than men do and these thought patterns are often associated with depressive symptoms (Nolen-Hoeksema et al., ). Based on these findings, we considered whether the relationship between rumination and depression is stronger in women than in men and if so, whether this might explain the higher prevalence of major depressive disorder (MDD) in women and finally, whether the association can be disrupted through a mind/body intervention. Adult men and women, most of whom were clinically depressed, participated in an intervention known as MAP Training, which combines "mental" training with silent meditation and "physical" training with aerobic exercise (Shors et al., ). After eight weeks of training, both men and women reported significantly fewer symptoms of depression and fewer ruminative thoughts (Alderman et al., ). Statistical correlations between depressive symptoms and ruminative thoughts were strong and significant (rho > 0.50; p depressive symptoms relate to "reflective" ruminations, which involve analyses of past events, feelings, and behaviors. This is also the only relationship that dissipated after the intervention. In general, these analyses suggest that the strength of the relationship between depressive symptoms and rumination does not necessarily explain sex differences in depression; but because the relationship is strong, targeting rumination through intervention can reduce the incidence of MDD, which is more prevalent among women. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Dilemma and quantum battle of sexes

    International Nuclear Information System (INIS)

    Nawaz, Ahmad; Toor, A H

    2004-01-01

    We analysed quantum version of the game battle of sexes using a general initial quantum state. For a particular choice of initial entangled quantum state it is shown that the classical dilemma of the battle of sexes can be resolved and a unique solution of the game can be obtained

  9. Sex reduces genetic variation: a multidisciplinary review.

    Science.gov (United States)

    Gorelick, Root; Heng, Henry H Q

    2011-04-01

    For over a century, the paradigm has been that sex invariably increases genetic variation, despite many renowned biologists asserting that sex decreases most genetic variation. Sex is usually perceived as the source of additive genetic variance that drives eukaryotic evolution vis-à-vis adaptation and Fisher's fundamental theorem. However, evidence for sex decreasing genetic variation appears in ecology, paleontology, population genetics, and cancer biology. The common thread among many of these disciplines is that sex acts like a coarse filter, weeding out major changes, such as chromosomal rearrangements (that are almost always deleterious), but letting minor variation, such as changes at the nucleotide or gene level (that are often neutral), flow through the sexual sieve. Sex acts as a constraint on genomic and epigenetic variation, thereby limiting adaptive evolution. The diverse reasons for sex reducing genetic variation (especially at the genome level) and slowing down evolution may provide a sufficient benefit to offset the famed costs of sex. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

  10. Sex selection: the systematic elimination of girls.

    Science.gov (United States)

    Oomman, Nandini; Ganatra, Bela R

    2002-05-01

    In strongly patriarchal societies, where the cultural and economic value of sons is at a premium, son preference manifests itself in many ways, ranging from differential allocation of household resources, medical care and neglect of girl children to female infanticide. With the increasing availability of ultrasound in the mid-1980s sex determination followed by sex-selective abortion began to become widespread as well. The following paper introduces this Roundtable and discusses the following questions: Is sex selection a part of women's right to free choice and control over their reproduction? What is the role of the medical profession? Are all manifestations of sex selection equally unethical? Are there solutions? Do the solutions themselves pose new ethical dilemmas? Following this paper, four respondents put different points of view on sex selection as a gender-based preference for a pregnancy; progress in getting the Supreme Court of India to implement a 1994 law regulating the use of antenatal diagnostic technology; why sex selection should be available as a form of reproductive choice; and why sex selection may be empowering for women and justify their actions in the short run, given the demands on them. All agree that only improved status for women and girls will reduce the demand for sex selection.

  11. Toward a Redefinition of Sex and Gender.

    Science.gov (United States)

    Unger, Rhoda Kesler

    1979-01-01

    Present psychological terminology facilitates biologically determinist models of sex differences, making it less likely that environmental sources of such differences will be explored. The term "gender," rather than "sex," should be used for those characteristics socioculturally considered appropriate to males and females.…

  12. Sex Differences in Cardiovascular Drug Response

    NARCIS (Netherlands)

    E.M. Rodenburg (Eline)

    2012-01-01

    textabstractIn the early sixties, a prominent professor in Clinical Pharmacology at the University College in London, D.R. Laurence, stated: “There are no clinically important sex differences in drug action, except, of course, to sex steroid hormones, but the subject is poorly documented. Women

  13. Sex Differences in the Experience of Widowhood.

    Science.gov (United States)

    Barrett, Carol J.

    Previous writers have presumed that widowhood is more stressful for one sex or the other. Hypotheses derived from demographic considerations and sex role developmental theory compared the needs and resources of 147 widows and 42 widowers, relative to 190 married persons. All subjects were non-institutionalized urban residents aged 62 or over. The…

  14. Number of Single-Sex Schools Growing

    Science.gov (United States)

    Barak, Tal

    2004-01-01

    The U.S. Department of Education's office for civil rights has proposed amending the regulations governing Title IX of the Education Amendments of 1972--which prohibits sex discrimination in programs that receive federal money--to allow more flexibility in offering single-sex schools or classes. This article discusses the rapid growth of…

  15. Sex Differences and Depression in Puerto Rico.

    Science.gov (United States)

    Canino, Glorisa J.; And Others

    1987-01-01

    Examined sex differences in rates of depressive disorders and depressive symptomatology, as measured by the Diagnostic Interview Schedule, for an island-wide probability sample of Puerto Rico. Found depression significantly more prevalent among women than men. Discusses risk factors from a sex-role and cultural perspective. (Author/KS)

  16. Social Conflict and Sex Equity in Education.

    Science.gov (United States)

    Quantz, Richard A.

    1983-01-01

    Holds that male/female differences in such behavior characteristics as aggression, cooperation/competition, compliance, and anxiety are not innate, but rather are social strategies available to both sexes and utilized whenever reasonable. Suggests that the sex equity problems in education can be solved by eliminating differential treatment of boys…

  17. Microbial manipulation of host sex determination

    NARCIS (Netherlands)

    Beukeboom, Leo W.

    A recent study in the lepidopteran Ostrinia scapulalis shows that endosymbionts can actively manipulate the sex determination mechanism of their host. Wolbachia bacteria alter the sex-specific splicing of the doublesex master switch gene. In ZZ males of this female heterogametic system, the female

  18. Lineage Selection and the Maintenance of Sex

    Science.gov (United States)

    de Vienne, Damien M.; Giraud, Tatiana; Gouyon, Pierre-Henri

    2013-01-01

    Sex predominates in eukaryotes, despite its short-term disadvantage when compared to asexuality. Myriad models have suggested that short-term advantages of sex may be sufficient to counterbalance its twofold costs. However, despite decades of experimental work seeking such evidence, no evolutionary mechanism has yet achieved broad recognition as explanation for the maintenance of sex. We explore here, through lineage-selection models, the conditions favouring the maintenance of sex. In the first model, we allowed the rate of transition to asexuality to evolve, to determine whether lineage selection favoured species with the strongest constraints preventing the loss of sex. In the second model, we simulated more explicitly the mechanisms underlying the higher extinction rates of asexual lineages than of their sexual counterparts. We linked extinction rates to the ecological and/or genetic features of lineages, thereby providing a formalisation of the only figure included in Darwin's “The origin of species”. Our results reinforce the view that the long-term advantages of sex and lineage selection may provide the most satisfactory explanations for the maintenance of sex in eukaryotes, which is still poorly recognized, and provide figures and a simulation website for training and educational purposes. Short-term benefits may play a role, but it is also essential to take into account the selection of lineages for a thorough understanding of the maintenance of sex. PMID:23825582

  19. Oral sex, oral health and orogenital infections

    Directory of Open Access Journals (Sweden)

    Rajiv Saini

    2010-01-01

    Full Text Available Oral sex is commonly practiced by sexually active male-female and same-gender couples of various ages, including adolescents. The various type of oral sex practices are fellatio, cunnilingus and analingus. Oral sex is infrequently examined in research on adolescents; oral sex can transmit oral, respiratory, and genital pathogens. Oral health has a direct impact on the transmission of infection; a cut in your mouth, bleeding gums, lip sores or broken skin increases chances of infection. Although oral sex is considered a low risk activity, it is important to use protection and safer sex precautions. There are various methods of preventing infection during oral sex such as physical barriers, health and medical issues, ethical issues and oral hygiene and dental issues. The lesions or unhealthy periodontal status of oral cavity accelerates the phenomenon of transmission of infections into the circulation. Thus consequences of unhealthy or painful oral cavity are significant and oral health should be given paramount importance for the practice of oral sex.

  20. Children in Same-Sex Marriages

    Science.gov (United States)

    Solodnikov, V. V.; Chkanikova, A. M.

    2009-01-01

    In Russia, sociologists do not have reliable statistical data as to the number of same-sex unions and the number of children being brought up in these families, and non-Russian studies on the topic are flawed and misleading. Russians are said to be antagonistic to the idea of children being raised in same-sex households. People are concerned over…

  1. Conflicting Philosophies of School Sex Education.

    Science.gov (United States)

    Reiss, Michael J.

    1995-01-01

    Explores the strengths and weaknesses of the five main philosophical positions currently found in school sex education. Argues that valid sex education promotes rational sexual autonomy, requires pupils to consider the needs and wishes of others, and occurs within a moral framework. Suggests teachers adopt a supportive but neutral position. (MJP)

  2. Participation in Sex Work: Students' Views

    Science.gov (United States)

    Roberts, Ron; Sanders, Teela; Myers, Ellie; Smith, Debbie

    2010-01-01

    Increasing evidence points to student involvement in the sex industry. The current study comprised a cross-sectional sample of 315 undergraduates at a London university. Using a semi-structured questionnaire, data were gathered on students' financial and employment circumstances and their views on participation in sex work. Results suggested…

  3. Inherent Dangers in Orogenital Sex During Pregnancy

    African Journals Online (AJOL)

    Coitus and cunnilingus during pregnancy are generally safe; whereas orogenital sex involving vaginal air insufflations can be very dangerous, causing even the death of the women. We carried out a search of case reports and reviews concerning air embolism during pregnancy due to orogenital sex. Physicians ...

  4. What's Missing? Anti-Racist Sex Education!

    Science.gov (United States)

    Whitten, Amanda; Sethna, Christabelle

    2014-01-01

    Contemporary sexual health curricula in Canada include information about sexual diversity and queer identities, but what remains missing is any explicit discussion of anti-racist sex education. Although there exists federal and provincial support for multiculturalism and anti-racism in schools, contemporary Canadian sex education omits crucial…

  5. Can Sex Education Delay Early Sexual Debut?

    Science.gov (United States)

    Erkut, Sumru; Grossman, Jennifer M.; Frye, Alice A.; Ceder, Ineke; Charmaraman, Linda; Tracy, Allison J.

    2013-01-01

    In this study, we examine whether a nine-lesson sex education intervention, "Get Real: Comprehensive Sex Education That Works," implemented in sixth grade, can reduce the number of adolescents who might otherwise become "early starters" of sexual activity (defined as heterosexual intercourse) by seventh grade. Participants were…

  6. The Gestalt Experiment in Sex Therapy.

    Science.gov (United States)

    Mosher, Donald L.

    1979-01-01

    The Gestalt experiment is applicable to sex therapy. Familiarity with modes and methods of experimenting permits the therapist's creativity to emerge. Applications of sexual metaphors and sex dysfunction as a nightmare are presented, using methods drawn from Gestalt dream work. The use of Gestalt experiments are illustrated in a client-therapist…

  7. Dangerous Liaisons: Substance Abuse and Sex.

    Science.gov (United States)

    Columbia Univ., New York, NY. National Center on Addiction and Substance Abuse.

    This report takes a comprehensive look at the connections between alcohol, drug use, and sex. Two national data sets on more than 34,000 teenagers and two sets on arrested and incarcerated sex offenders were analyzed. A review of the literature, interviews with experts, and an examination of programs aimed at prevention of abuse were included in…

  8. Sex Role Stereotypes Are Alive and Well.

    Science.gov (United States)

    Snodgrass, Sara E.

    Two studies, in late 1988 and early 1990, examined sex-role stereotypes held by northeastern liberal arts college students (N=719) and southern state university college students (N=145). The first study used the Personal Attributes Questionnaire (PAQ) and compared ratings of men and women with the traditional sex-roles represented by the PAQ in…

  9. Occupational Segregation by Sex: Determinants and Changes.

    Science.gov (United States)

    Beller, Andrea H.

    1982-01-01

    This study found that occupational sex segregation began to diminish during the 1970s, in conjunction with enforcement of the equal employment opportunity laws against sex discrimination in employment. The success of these laws suggests that discrimination was originally a determinant of occupational segregation. (Author/SK)

  10. 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.

  11. Questions and Answers about Sex (For Parents)

    Science.gov (United States)

    ... español Preguntas y respuestas sobre sexo Answering their kids' questions about sex is a responsibility that many parents dread. Otherwise ... avoided. Parents can help foster healthy feelings about sex if they answer kids' questions in an age-appropriate way. When do ...

  12. 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 ...

  13. Sex Parties: Female Teen Sexual Experimentation

    Science.gov (United States)

    Toscano, Sharyl Eve

    2006-01-01

    Adolescent participants in a study aimed at exploring the nature and characteristics of girls' dating relationships revealed the phenomenon of sex parties. These teens defined a "sex party" as an opportunity to engage in sexual contact outside of typical dating relationships. Sexual activity could involve actual intercourse, but usually involved…

  14. Sex Roles among Married and Unmarried Couples.

    Science.gov (United States)

    Kotkin, Mark

    1983-01-01

    An investigation of sex roles among married and cohabitating couples showed: (1) that male career success, male career precedence, the decision to marry, and conventional allocation of household tasks are all concomitant and (2) that marriage crystallizes sex roles and behaviorally solidifies male career precedence, facilitating the husband's…

  15. Sex Trait Stereotypes in Malaysian Children.

    Science.gov (United States)

    Ward, Colleen

    1985-01-01

    To examine the development of sex-role stereotyping in Malaysia, 80 children were tested with the Sex Stereotype Measurement II. Results revealed that stereotyping increases with age, that the male stereotype is more easily recognized than the female, and that boys are more familiar with the male stereotype than are girls. (KH)

  16. Sex Differences in the Adolescent Brain

    Science.gov (United States)

    Lenroot, Rhoshel K.; Giedd, Jay N.

    2010-01-01

    Adolescence is a time of increased divergence between males and females in physical characteristics, behavior, and risk for psychopathology. Here we will review data regarding sex differences in brain structure and function during this period of the lifespan. The most consistent sex difference in brain morphometry is the 9-12% larger brain size…

  17. Teaching Sex Education to Multiply Handicapped Adolescents.

    Science.gov (United States)

    Smigielski, Patricia A.; Steinmann, Mary J.

    1981-01-01

    A sex education program for an adolescent who is mentally retarded or blind must emphasize concrete teaching, visual compensators, resource persons, repetition of content, and opportunities for social learning. Nurses and special educators can serve as consultants to health educators in planning a sex education program. (JN)

  18. Licensed Practical Nurses' Sex Role Stereotypes.

    Science.gov (United States)

    Wallston, Barbara Strudler; And Others

    1983-01-01

    Examined whether sex-role stereotypes would affect nurses' (N=32) attitudes toward simulations of male and female patients. Emotional style and patients' diagnosis were manipulated. Results showed significant sex-role differences and stereotypical attitudes. Male patients were rated more positively, and were more likely to possess traditional male…

  19. 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.

  20. Perceived control and communication about sex: A study of South ...

    African Journals Online (AJOL)

    Caregiver–youth communication about sex protects youth against HIV/AIDS, and caregivers who believe that sex knowledge is important are more likely to talk to their youth about sex. However, caregivers who experience barriers to communication about sex may not talk to their youth about sex even if the caregiver ...

  1. The accuracy of 2D ultrasound prenatal sex determination ...

    African Journals Online (AJOL)

    Most of the women were happy even when the sex differed from that which they desired. Conclusion: Prenatal sonographic sex determination has a high sensitivity index. Consequently we advocate its use prior to more invasive sex tests. Keywords: Accuracy, gender determination, prenatal gender, prenatal sex, sex ...

  2. Need for Studies of Sex Discrimination in Public Schools.

    Science.gov (United States)

    1972

    This paper was designed to aid organizations seeking to eliminate sex discrimination in the public schools. Major emphasis was placed on the need for studies of sex discrimination. Six areas of investigation should include: 1) one sex schools; 2) one sex or practically one sex courses in co-ed schools; 3) physical education, sports and other extra…

  3. Resources for Achieving Sex Equity: An Annotated Bibliography.

    Science.gov (United States)

    Miller, Susan W., Comp.

    This annotated bibliography provides a list of resources dealing with sex equity in vocational education. The bibliography first provides operational definitions of "sexism,""sex fair,""sex affirmative,""sex bias," and "affirmative action." It then lists resources under the following topics and/or bibliographic forms: (1) sex role definition, (2)…

  4. How sex work becomes an option: Experiences of female sex workers in Kerman, Iran.

    Science.gov (United States)

    Karamouzian, Mohammad; Foroozanfar, Zohre; Ahmadi, Azal; Haghdoost, Ali Akbar; Vogel, Joanna; Zolala, Farzaneh

    2016-01-01

    Sex work is rarely an occupation of choice for Iranian women and is often described as a last resort. While several factors play a role in creating an environment where individuals become involved in sex work, female sex workers' experiences regarding entry into sex work in Iran are poorly understood. In this qualitative study, a convenience sample of 24 participants was recruited from a drop-in centre for vulnerable women in Kerman, Iran. Through in-depth interviews, participants were asked about their personal lived experiences of initiating sex work. Grounded theory was used to analyse findings from this research. We learned that major factors impacting on women's initiation into sex work circulated around their vulnerability and chronic poverty. Participants continued to sell sex due to their limited opportunities, drug dependence and financial needs. Improving sex workers' economic status could be a vital intervention in providing vulnerable women with options other than sex work. Female sex workers should be provided with government support and educational programmes delivered through special centres. Despite the illegal status of their work, sex workers' needs should be recognised across all aspects of policy and legislation.

  5. Why we should consider sex (and study sex differences) in addiction research.

    Science.gov (United States)

    Sanchis-Segura, Carla; Becker, Jill B

    2016-09-01

    Among mammals, every cell has a biological sex, and the sex of an individual pervades its body and brain. In this review, we describe the processes through which mammals become phenotypically male or female by organizational and activational influences of genes and hormones throughout development. We emphasized that the molecular and cellular changes triggered by sex chromosomes and steroid hormones may generate sex differences in overt physiological functions and behavior, but they may alternatively promote end-point convergences between males and females. Clinical and pre-clinical evidences suggest that sex and gender differences modulate drug consumption as well as of the transition towards drug-promoted pathological states such as dependence and addiction. Additionally, sex differences in drug pharmacokinetics and pharmacodynamics will also influence dependence and addiction as well as side effects of drugs. These effects will further interact with socially gendered factors to result in sex differences in the access to, engagement in and efficacy of any therapeutic attempt. Finally, we maintain that 'sex sameness' is as important as 'sex differences' when building a complete understanding of biology for both males and females and provide a framework with which to classify and guide investigation into the mechanisms mediating sex differences and sex sameness. © 2016 Society for the Study of Addiction.

  6. Sex steroids and glucose metabolism

    Directory of Open Access Journals (Sweden)

    Carolyn A Allan

    2014-04-01

    Full Text Available Testosterone levels are lower in men with metabolic syndrome and type 2 diabetes mellitus (T2DM and also predict the onset of these adverse metabolic states. Body composition (body mass index, waist circumference is an important mediator of this relationship. Sex hormone binding globulin is also inversely associated with insulin resistance and T2DM but the data regarding estrogen are inconsistent. Clinical models of androgen deficiency including Klinefelter's syndrome and androgen deprivation therapy in the treatment of advanced prostate cancer confirm the association between androgens and glucose status. Experimental manipulation of the insulin/glucose milieu and suppression of endogenous testicular function suggests the relationship between androgens and insulin sensitivity is bidirectional. Androgen therapy in men without diabetes is not able to differentiate the effect on insulin resistance from that on fat mass, in particular visceral adiposity. Similarly, several small clinical studies have examined the efficacy of exogenous testosterone in men with T2DM, however, the role of androgens, independent of body composition, in modifying insulin resistance is uncertain.

  7. [Neuroendocrine effect of sex hormones].

    Science.gov (United States)

    Babichev, V N

    2005-01-01

    The paper provides a generalization of data and the results of own experiments on influence ovarian steroids on the hypothalamus and other brain areas related to reproduction. Ovarian hormones have widespread effects throughout the brain: on catecholaminergic neurons and serotonergic pathways and the basal forebrain cholinergic system, as well as the hipocampus, spinal cord, nigrostriatal and mesolimbic system, in addition to glial cells and blood-brain barrier. The widespread influences of these various neuronal systems ovarian steroids have measurable effects on mood and affect as well as on cognition, with implications for dementia. There are developmentally programmed sex differenced in hippocampal structure that may help to explain differences in the strategies which male and female rats use to solve spatial navigation problems. The multiple sites and mechanisms of estrogen action in brain underlie a variety of importants effects on cognitive and other brain functions--coordination of movement, pain, affective state, as well as possible protection in Alzheimer's disease. Estrogen withdrawal after natural or surgical menopause can lead to a host of changes in brain function and behavior.

  8. 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.

  9. Perceptions of sources of sex education and targets of sex communication: sociodemographic and cohort effects.

    Science.gov (United States)

    Sprecher, Susan; Harris, Gardenia; Meyers, Adena

    2008-01-01

    As part of a larger survey study on young adult sexuality conducted over a 17-year period at a Midwest U.S. university, more than 6,000 college students completed questions on the sources of their sex education and the degree to which they have communicated about sex with various types of individuals. Participants reported receiving more sex education from peers and media than from parents (and mothers more than fathers). Respondents also reported communicating more about sex with peers than with parents or any other categories of individuals. Differences were found in the degree of sex education from various sources and in communication with various targets based on gender, ethnic background, and social class. Furthermore, changes were found over the 17-year period. More recent cohorts of students perceived that they received more sex education from media, peers, and professionals, and communicated more about sex with professionals, relative to earlier cohorts.

  10. Apomixis and the problem of obtaining haploids and homozygote diploids in pear (Pyrus communis L.

    Directory of Open Access Journals (Sweden)

    Є. О. Долматов

    2013-02-01

    Full Text Available The article highlights results of research over simulative apomixes in pear and its utilization for obtaining haploids and homozygote diploids. It has been established that over 50% pear varieties with failed remote hybridization are capable of generating seeds of apomictic origin producing diploid plants. Genotypes displaying maximal inclination to apomixes have been singled out. Apomictic pear seedlings obtained from foreign pollination within the limits of the same combination are inherent in profound morphological diversity. Fruit-bearing apomicts originated from one and the same maternal plant differ to the same extent as hybrid seedlings of the same family. Genetic markers have enabled to establish that these are embryo sacs in which meiosis has completed that give rise to apomictic seeds. In vitro method as used for the purpose of increasing apomictic plants output has been illustrated. The greatest induction of apomictic shoots in vitro has been reached by alternation of BAP cytokinin at concentration of 1mg/l and 2 mg/l on the background of GA3 amounting to 1,5 mg/l. Grafting with shoots in vitro on non-sterile rootstocks of pear (Pyrus communis has increased the output of plants up to 80%. A cytological assessment of 9 apomictic samples is provided. The cytological analysis of samples of apomictic forms has certified the presence of simulative haploid parthenogenesis in pear.

  11. Complex Interspecific Hybridization in Barley (Hordeum vulgare L.) and the Possible Occurrence of Apomixis

    DEFF Research Database (Denmark)

    Bothmer, R. von; Bengtsson, M.; Flink, J.

    1988-01-01

    Several complex hybrids were produced from the combination [(Hordeum lechleri, 6 .times. .times. H. procerum, 6 .times.) .times. H. vulgare, 2 .times.]. Crosses with six diploid barley lines resulted in triple hybrids, most of which had a full complement of barley chromosomes (no. 1-7), but were...

  12. Exploring dynamics of anal sex among female sex workers in Andhra Pradesh.

    Science.gov (United States)

    Tucker, Saroj; Krishna, Rama; Prabhakar, Parimi; Panyam, Swarup; Anand, Pankaj

    2012-01-01

    The anal sex among heterosexual couples is on the rise as reported in many scientific studies. Considering that unprotected anal sex has higher risk of human immunodeficiency virus (HIV) transmission than the vaginal sex, we undertook a study to understand the anal sex practices among Female Sex Workers (FSW). The study was conducted among FSW attending 11 randomly selected sexually transmitted infection (STI) clinics in Bill and Melinda Gates supported targeted interventions in Andhra Pradesh. A structured questionnaire was administered to the 555 FSW attending these clinics by project clinic counselors. Informed consent was obtained from all the study participants. Engaging in anal sex was self reported by 22% of sex workers, though demand from clients was reported to be much higher (40%). The reasons for anal sex practices included more money (61%), clout/influence of the client (45%), risk of losing client (27%), and forced sex (1.2%). Factors associated with anal sex were higher number of clients, higher duration of sex work, higher income, and older age group. Associated risks perceived by FSW were bleeding and injury to anal canal (98%) while only 28% associated it with higher HIV transmission risk. Reported Condom and lubricant use was about 88% and 39% respectively. The study shows that there is frequent anal sex, inconsistent condom and infrequent lubricant usage, economic and physical coercion, and low awareness of STI/HIV transmission risk among FSW, which have serious implications for HIV prevention programmes. There is a need to focus on anal sex education and use of lubricants along with condoms during anal sex in FSW-targeted interventions in AP.

  13. The evolution of female sex pheromones

    Directory of Open Access Journals (Sweden)

    Ally R. HARARI, Hadass STEINITZ

    2013-08-01

    Full Text Available The role of female sex pheromones in natural selection, particularly as a means for species recognition to avoid the generation of hybrid offspring with low fitness, has been widely explored and is generally accepted by scholars. However, the significance of sex pheromones in shaping mate choice (sexual selection and in competition over breeding resources (social selection has been largely ignored. The effect of sexual selection on sex pheromones as a sexually dimorphic signaling trait has been discounted because the amount of pheromone released by females is typically minute, while the role of sex pheromones in competition over breeding resources (other than mates has not yet been considered. As a result of natural selection, variation in sex pheromones among females is expected to be low, and males are not expected to choose their mates among pheromone-releasing conspecific females. Sexual selection, on the other hand, should drive the increase in pheromone variance among females, and males are expected to choose females based on this variation. Moreover, social selection resulting from more general social interactions, for example competition among females for breeding sites and food, should also promote variance among female sex pheromones. Here, we review the current evidence for each of the three selection processes acting on sex pheromones of female moths as an advertising trait. We suggest that the three selection types are not mutually exclusive but rather act together to promote different fitness components in diverse ecological situations [Current Zoology 59 (4: 569–578, 2013].

  14. Putting sex education in its place.

    Science.gov (United States)

    Cassell, C

    1981-04-01

    In order to help reduce fears and anxieties regarding the influence of sex education in a public school setting, school and community sexuality educators need to better articulate the difference between formal and structured sex education and non-formal, informal and incidental sex learning. Sex education is only 1 aspect of the sexual learning process. 2 main points have to be clarified for parents and the general public to set the stage for a new way to view the school and community involvement in the sexual learning process: the schools' sexuality education courses constitute only a small portion of the sexual learning process; and sexual learning is not an event for youth only, but a process spanning life. Sex education (the process) connotates an academic setting with a specific curricula taught by a trained instructor, but sexual learning relates to environmental, non-formal incidental learning from a multitude of sources. Studies indicate that teenagers receive about 90% of their contraceptive and sexuality informaation from peers and mass media and that these sources of information are becoming their preferred sources of sex education. What is needed is a way to address and improve the conditions of sexual learning in the community. As home is the ideal environment for primary and positive sexual learning, parents need support in their role as sex educators. Classroom sexuality education curricula in all school settings have a solid place in the process of sexual learning.

  15. Sexual Murderers: Sex Offender, Murderer, or Both?

    Science.gov (United States)

    Beauregard, Eric; DeLisi, Matt; Hewitt, Ashley

    2017-06-01

    Sexual murderers perpetrate homicide and rape/sexual abuse, but it is unclear whether they should primarily be considered homicide offenders, sexual offenders, or both. Most studies have merged together different types of non-homicidal sex offenders (NHSOs), neglecting to consider the potential differences between the nonviolent and violent sex offenders. Here, we suggest it is important to isolate those violent sex offenders who inflict severe physical injuries that could potentially lead to a lethal outcome. Therefore, the aim of the current study is to compare different measures of the criminal career on three groups of sex offenders: NHSOs, violent NHSOs, and sexual homicide offenders (SHOs) using data from 616 incarcerated male sex offenders in a Federal penitentiary in Canada. Interestingly, the group of sex offenders with the worst criminal career profile was not the SHOs, but the violent NHSOs. Violent NHSOs had the greatest number of prior convictions and the most varied and versatile criminal career. Therefore, we suggest that based on their criminal career, SHOs should be considered more as murderers than sex offenders. However, to fully answer this question, future studies should include a group of non-sexual homicide offenders.

  16. Sex and Management of Rheumatoid Arthritis.

    Science.gov (United States)

    Favalli, Ennio Giulio; Biggioggero, Martina; Crotti, Chiara; Becciolini, Andrea; Raimondo, Maria Gabriella; Meroni, Pier Luigi

    2018-01-26

    Rheumatoid arthritis (RA) is a chronic and progressive autoimmune disease more common in women than men (3:1). Although sex-based differences may play a complex role in promoting an autoimmune dysfunction, to date the comprehensive knowledge of the link between sex and RA is still partially lacking. Furthermore, males and females have been demonstrated to differently deal with their chronic pathologies, modifying the perceived sex-based burden of disease. Gender medicine is a newly approach focusing on the impact of gender differences on human physiology, pathophysiology, and clinical features of diseases, analyzing the complex interrelation and integration of sex and psychological and cultural behavior. A better comprehension of possible factors influencing sexual dimorphism in RA susceptibility, pattern of presentation, disease activity, and outcome could contribute to a tailored approach, in order to limit the morbidity of the disease. RA disease activity seems to be higher in women, whereas the response rate to synthetic and biologic disease-modifying therapies appears to be better in males. Moreover, the common strategies for RA management may be affected by concomitant pregnancy or childbearing desire, with particular regard to treatments with potential teratogenic effects or impact on fertility. Finally, comorbidities, such as fibromyalgia, major depression, and osteoporosis, are more frequent in females, while the impact of sex on cardiovascular risk is still controversial. Moving from the role of sex in influencing RA pathogenesis, epidemiology, and disease characteristics, this review explores the evidence on how sex can have an impact on strategies for managing patients with RA.

  17. Sex education vital for Chinese adolescents.

    Science.gov (United States)

    Zhang, Z

    1997-02-01

    This article summarizes findings from a survey conducted among adolescents in Beijing and Tianjin, China. Findings indicate that 89.3% of sex offenders were adolescents. Many high school students were engaged in premarital sexual relations, but lacked knowledge about sex and contraception. Premarital sex and sexually transmitted diseases are considered a social evil. The central government has direct jurisdiction in Tianjin and its population of 9 million. By 1989 there were 540,000, or 12% of total population, aged 12-16 years. A survey of 3231 junior middle school students aged 11-14 years revealed that 35% of girls did not know why menstruation occurred at a certain age. About 55% of boys did not know about erections. 35% considered an erect penis a part of normal physical development, but over 50% were confused. 30-50% of students who had reached menarche and sexual maturity found it difficult to find knowledgeable people. 50% received information from the mass media. 44% of girls learned from their mothers. 25% of boys and girls aged 11-12 years already had girlfriends and boyfriends. About 30% desired friends of the opposite sex and desired intimacy, love, and dependability among friends. It is argued that the backward notions of sex originated in a once feudal society that considered sex a taboo. Parents, teachers, and school authorities are resistant to introducing sex education; teachers are embarrassed by the subject matter. In Beijing about 4000 students aged 11-14 years were interviewed. These students had limited information on sex-related issues and misconceptions. Attitudes must be changed and teachers must be trained before adolescent health and sex education can be introduced into schools. The government can play a role in promoting programs for adolescents and coordinating the efforts of nongovernmental groups.

  18. Risk of sex-specific cancers in opposite-sex and same-sex twins in Denmark and Sweden

    DEFF Research Database (Denmark)

    Ahrenfeldt, Linda Juel; Skytthe, Axel; Möller, Sören

    2015-01-01

    -scale prospective twin study compared opposite-sex (OS) and same-sex (SS) twins to test the impact of intrauterine exposures on cancer risk. Based on the Danish and Swedish twin and cancer registries, we calculated incidence rate ratios for OS and SS twins while standardized incidence ratios (SIRs) with 95......% confidence intervals (CIs) were calculated for OS/SS twins compared with the general population. RESULTS: A total of 18,001 cancers were identified during 1943-2009. No significant differences were observed between OS and SS twins, neither for the sex-specific cancers nor for cancer at all sites. All...... to prenatal testosterone - does not increase the risk of sex-specific cancers in OS females. Furthermore, the study supports that twinning per se is not a risk factor of cancer. IMPACT: Findings are reassuring as they fail to provide evidence for the hypothesis that endocrine or other difference...

  19. Molecular study of developmental sex disorders in children

    African Journals Online (AJOL)

    Soheir S. AboElella

    2015-03-07

    Mar 7, 2015 ... development, causing divergences between genetic sex, gonadal sex and phenotypic sex ... neonatal history of failure to thrive, vomiting, skin pigmen- tations and .... of them (12 & 14) suffered from hypoglycemia. Hormonal ...

  20. Genetics Home Reference: 46,XX testicular disorder of sex development

    Science.gov (United States)

    ... 46,XX testicular disorder of sex development 46,XX testicular disorder of sex development Printable PDF Open ... to view the expand/collapse boxes. Description 46,XX testicular disorder of sex development is a condition ...

  1. Globalization and male sex trade in Ghana: Modernity or Immorality ...

    African Journals Online (AJOL)

    Globalization and male sex trade in Ghana: Modernity or Immorality? ... apolitical and less hypocritical way of discussing the issue devoid of criminalization, in the ... Key words: Globalization, homosexuality, male sex trade, sex culture, Ghana.

  2. Sex Robots: Between Human and Artificial

    OpenAIRE

    Richardson, Kathleen

    2017-01-01

    Despite a surplus of human beings in the world, new estimates total 7 and a half billion, we appear to be at the start of an attachment crisis - a crisis in how human beings make intimate relationships. Enter the sex robots, built out of the bodies of sex dolls to help humans, particularly males escape their inability to connect. What does the rise of sex robots tell us about the way that women and girls are imagined, are they persons or property? And to what extent is porn, prostitution and ...

  3. Treating infidelity in same-sex couples.

    Science.gov (United States)

    Martell, Christopher R; Prince, Stacey E

    2005-11-01

    Psychotherapy with same-sex couples does not differ markedly from standard couple therapies; this is also true for treating couples facing infidelity. However, same-sex couples often design their relationships differently, without tradition and formal marital contracts to prescribe behavior. Based on clinical experience and the empirical research, this article addresses the differing norms involved in affirmatively treating infidelity in gay and lesbian couples within the framework of integrative behavioral couple therapy (IBCT). Two cases illustrate the process and outcome of IBCT with same-sex couples.

  4. Same-sex marriage and mental health.

    Science.gov (United States)

    Liangas, Georgios; Athanasou, James A

    2016-12-01

    It has been proposed that legislation for same-sex marriage has a positive mental health benefit. The purpose of this paper is to review and evaluate the empirical and conceptual links between same-sex marriage and mental health. There are substantive methodological issues in the four surveys and comparisons undertaken. Difficulties with the validity of the evidence are discussed. Conceptual difficulties in the arguments relating to victimisation as well as the psychology of marriage are highlighted. It was concluded that it is premature to make claims of causality vis-a-vis same-sex marriage legislation and mental health. © The Royal Australian and New Zealand College of Psychiatrists 2016.

  5. 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.

  6. 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

  7. 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...

  8. 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...

  9. Have sex or not? Lessons from bacteria.

    Science.gov (United States)

    Lodé, T

    2012-01-01

    Sex is one of the greatest puzzles in evolutionary biology. A true meiotic process occurs only in eukaryotes, while in bacteria, gene transcription is fragmentary, so asexual reproduction in this case really means clonal reproduction. Sex could stem from a signal that leads to increased reproductive output of all interacting individuals and could be understood as a secondary consequence of primitive metabolic reactions. Meiotic sex evolved in proto-eukaryotes to solve a problem that bacteria did not have, namely a large amount of DNA material, occurring in an archaic step of proto-cell formation and genetic exchanges. Rather than providing selective advantages through reproduction, sex could be thought of as a series of separate events which combines step-by-step some very weak benefits of recombination, meiosis, gametogenesis and syngamy. Copyright © 2012 S. Karger AG, Basel.

  10. Sex determination: insights from the silkworm

    Indian Academy of Sciences (India)

    2010-09-06

    determination pathway that controls most sex-specific phenotypes, is a .... Sports and Culture, Government of Japan, grant-in-aid for Young. Scientists ... Berghammer A. J., Klingler M. and Wimmer E. A. 1999 A universal marker for ...

  11. Sex determination: ways to evolve a hermaphrodite.

    OpenAIRE

    Braendle , Christian; Félix , Marie-Anne

    2006-01-01

    Most species of the nematode genus Caenorhabditis reproduce through males and females; C. elegans and C. briggsae, however, produce self-fertile hermaphrodites instead of females. These transitions to hermaphroditism evolved convergently through distinct modifications of germline sex determination mechanisms.

  12. Sexing code subversion, theory and representation

    CERN Document Server

    Herbst, Claudia

    2008-01-01

    Critically investigating the gender of programming in popular culture, Sexing Code proposes that the de facto representation of technical ability serves to perpetuate the age-old association of the male with intellect and reason, while identifying the fem

  13. Sex hormone replacement in Turner syndrome

    DEFF Research Database (Denmark)

    Trolle, Christian; Hjerrild, Britta; Cleemann, Line Hartvig

    2012-01-01

    The cardinal features of Turner syndrome (TS) are short stature, congenital abnormalities, infertility due to gonadal dysgenesis, with sex hormone insufficiency ensuing from premature ovarian failure, which is involved in lack of proper development of secondary sex characteristics and the frequent...... osteoporosis seen in Turner syndrome. But sex hormone insufficiency is also involved in the increased cardiovascular risk, state of physical fitness, insulin resistance, body composition, and may play a role in the increased incidence of autoimmunity. Severe morbidity and mortality affects females with Turner...... syndrome. Recent research emphasizes the need for proper sex hormone replacement therapy (HRT) during the entire lifespan of females with TS and new hypotheses concerning estrogen receptors, genetics and the timing of HRT offers valuable new information. In this review, we will discuss the effects...

  14. Genetic sexing of the Mediterranean fruit fly

    International Nuclear Information System (INIS)

    1990-01-01

    In the early 1980s, it was recognized by the FAO and the IAEA that a genetic sexing method for the Mediterranean fruit fly (medfly) would greatly improve the efficacy of the medfly sterile insect technique (SIT) and reduce its costs. These Proceedings summarize the research and development findings of the Agency's co-operators in the co-ordinated research programme to develop a genetic sexing method for the medfly. Great progress has been made in many aspects of medfly genetics. including the development of a number of genetic sexing strains. Contents: Genetics, Cytogenetics and Population Genetics. Genetic Sexing of Ceratitis Capitata by Morphological, Biochemical and other means. Recommendations. Refs, figs and tabs

  15. 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...

  16. Sex work on the rise. International news.

    Science.gov (United States)

    1996-01-01

    The AIDS epidemic has brought to the fore many social injustices; for instance, inappropriate laws. The groups of people most at risk of HIV/AIDS are women, young people, and sex workers. More appropriate laws are needed to protect their rights. In many instances sex workers are prosecuted for selling their services, but their clients are not prosecuted for seeking these services. Most people become sex workers so they can feed, clothe, and supply the basic needs for themselves and their families. Many sex workers are abandoned wives, mothers with no means of support, and poverty stricken people. A Health Ministry commission in Sweden proposed that prostitutes, clients, and pimps be prosecuted and be liable to imprisonment. Authorities in Scotland, where prostitution is illegal, have granted licenses to more than 20 clubs in Edinburgh in which sex is for sale. In the UK, the Royal College of Nursing called for a measure to decriminalize prostitution and to introduce licensed, regulated brothels. The legalization of sex clubs and brothels will occur soon in the Netherlands. In Poland, 30,000-50,000 youth, 33% of whom are underage, sell sex during holidays. Organizations are beginning to work only with male prostitutes in Belgium. In the countries of the former Soviet Union and China, prostitution is becoming more and more common. Some young girls in these countries practice currency prostitution. In almost all Asian countries except Thailand condom use is low; yet prostitution and sexually transmitted diseases are very common. Some people participate in the corrupt trade in women from Nepal to supply the sex market in Bombay, India. Sex tourism is still common in cities of Eastern Europe and the former USSR and in areas where tourism is increasing. There are more than 1 million prostitutes aged under 16 in eight Asian countries, with 400,000 in India. Sweden and the UK have taken steps to prosecute natives who have sex with children abroad. Philippine authorities

  17. Invited review: sex ratio and rheumatic disease.

    Science.gov (United States)

    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

  18. Gender Stereotypes in Same-Sex Relationships

    OpenAIRE

    Bro, Jesper Koch; Jensen, Ditte; Stokholm, Martin Valdemar Sachse; Kristoffersen, Simone Ryegaard; Tranberg, Line Falk

    2008-01-01

    Abstract Through five qualitative interviews with people that currently are or have been in same-sex relationship, analyzed by applying the theories of social constructivism by Peter L. Berger and Thomas Luckmann and Queer theorist Judith Butler, the project explores heterosexual stereotypes in same-sex relationships. The result is a thoroughgoing analysis where it appears from the interviews as if the interviewed people reproduce heterosexual stereotypical gender roles in their relationships...

  19. 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.

  20. Atomoxetine in abstinent cocaine users: Sex differences

    Directory of Open Access Journals (Sweden)

    Elise E. DeVito

    2017-10-01

    Full Text Available Data presented are from a sex-differences secondary analysis of a human laboratory investigation of single doses of atomoxetine (40 mg and 80 mg versus placebo in abstinent individuals with cocaine use disorders (CUD. Subjective drug effects, cognitive performance and cardiovascular measures were assessed. The primary atomoxetine dose analyses (which do not consider sex as a factor are reported in full elsewhere (DeVito et al., 2017 [1].