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Sample records for fitting aga asexual

  1. A simple algorithm for optimization and model fitting: AGA (asexual genetic algorithm)

    Science.gov (United States)

    Cantó, J.; Curiel, S.; Martínez-Gómez, E.

    2009-07-01

    Context: Mathematical optimization can be used as a computational tool to obtain the optimal solution to a given problem in a systematic and efficient way. For example, in twice-differentiable functions and problems with no constraints, the optimization consists of finding the points where the gradient of the objective function is zero and using the Hessian matrix to classify the type of each point. Sometimes, however it is impossible to compute these derivatives and other type of techniques must be employed such as the steepest descent/ascent method and more sophisticated methods such as those based on the evolutionary algorithms. Aims: We present a simple algorithm based on the idea of genetic algorithms (GA) for optimization. We refer to this algorithm as AGA (asexual genetic algorithm) and apply it to two kinds of problems: the maximization of a function where classical methods fail and model fitting in astronomy. For the latter case, we minimize the chi-square function to estimate the parameters in two examples: the orbits of exoplanets by taking a set of radial velocity data, and the spectral energy distribution (SED) observed towards a YSO (Young Stellar Object). Methods: The algorithm AGA may also be called genetic, although it differs from standard genetic algorithms in two main aspects: a) the initial population is not encoded; and b) the new generations are constructed by asexual reproduction. Results: Applying our algorithm in optimizing some complicated functions, we find the global maxima within a few iterations. For model fitting to the orbits of exoplanets and the SED of a YSO, we estimate the parameters and their associated errors.

  2. A simple algorithm for optimization and model fitting: AGA (asexual genetic algorithm)

    CERN Document Server

    Canto, J; Martinez-Gomez, E; 10.1051/0004-6361/200911740

    2009-01-01

    Context. Mathematical optimization can be used as a computational tool to obtain the optimal solution to a given problem in a systematic and efficient way. For example, in twice-differentiable functions and problems with no constraints, the optimization consists of finding the points where the gradient of the objective function is zero and using the Hessian matrix to classify the type of each point. Sometimes, however it is impossible to compute these derivatives and other type of techniques must be employed such as the steepest descent/ascent method and more sophisticated methods such as those based on the evolutionary algorithms. Aims. We present a simple algorithm based on the idea of genetic algorithms (GA) for optimization. We refer to this algorithm as AGA (Asexual Genetic Algorithm) and apply it to two kinds of problems: the maximization of a function where classical methods fail and model fitting in astronomy. For the latter case, we minimize the chi-square function to estimate the parameters in two e...

  3. Genetic diversity and fitness in small populations of partially asexual, self-incompatible plants.

    Science.gov (United States)

    Navascués, M; Stoeckel, S; Mariette, S

    2010-05-01

    How self-incompatibility systems are maintained in plant populations is still a debated issue. Theoretical models predict that self-incompatibility systems break down according to the intensity of inbreeding depression and number of S-alleles. Other studies have explored the function of asexual reproduction in the maintenance of self-incompatibility. However, the population genetics of partially asexual, self-incompatible populations are poorly understood and previous studies have failed to consider all possible effects of asexual reproduction or could only speculate on those effects. In this study, we investigated how partial asexuality may affect genetic diversity at the S-locus and fitness in small self-incompatible populations. A genetic model including an S-locus and a viability locus was developed to perform forward simulations of the evolution of populations of various sizes. Drift combined with partial asexuality produced a decrease in the number of alleles at the S-locus. In addition, an excess of heterozygotes was present in the population, causing an increase in mutation load. This heterozygote excess was enhanced by the self-incompatibility system in small populations. In addition, in highly asexual populations, individuals produced asexually had some fitness advantages over individuals produced sexually, because sexual reproduction produces homozygotes of the deleterious allele, contrary to asexual reproduction. Our results suggest that future research on the function of asexuality for the maintenance of self-incompatibility will need to (1) account for whole-genome fitness (mutation load generated by asexuality, self-incompatibility and drift) and (2) acknowledge that the maintenance of self-incompatibility may not be independent of the maintenance of sex itself.

  4. Mutation accumulation and fitness effects in hybridogenetic populations: a comparison to sexual and asexual systems

    Directory of Open Access Journals (Sweden)

    Bagheri Homayoun C

    2007-05-01

    Full Text Available Abstract Background Female only unisexual vertebrates that reproduce by hybridogenesis show an unusual genetic composition. They are of hybrid origin but show no recombination between the genomes of their parental species. Instead, the paternal genome is discarded from the germline prior to meiosis, and gametes (eggs only contain solely unrecombined maternal genomes. Hence hybridogens only transmit maternally inherited mutations. Hybridity is restored each generation by backcrossing with males of the sexual parental species whose genome was eliminated. In contrast, recombining sexual species propagate an intermixed pool of mutations derived from the maternal and paternal parts of the genome. If mutation rates are lower in female gametes than males, it raises the possibility for lower mutation accumulation in a hybridogenetic population, and consequently, higher population fitness than its sexual counterpart. Results We show through Monte-Carlo simulations that at higher male to female mutation ratios, and sufficiently large population sizes, hybridogenetic populations can carry a lower mutation load than sexual species. This effect is more pronounced with synergistic forms of epistasis. Mutations accumulate faster on the sexual part of the genome, and with the purifying effects of epistasis, it makes it more difficult for mutations to be transmitted on the clonal part of the genome. In smaller populations, the same mechanism reduces the speed of Muller's Ratchet and the number of fixed mutations compared to similar asexual species. Conclusion Since mutation accumulation can be less pronounced in hybridogenetic populations, the question arises why hybridogenetic organisms are so scarce compared to sexual species. In considering this, it is likely that comparison of population fitnesses is not sufficient. Despite competition with the sexual parental species, hybrid populations are dependent on the maintenance of – and contact with – their

  5. Appropriate for gestational age (AGA)

    Science.gov (United States)

    Fetal age; Gestation; Development - AGA; Growth - AGA; Neonatal care - AGA; Newborn care - AGA ... can range from 38 to 42 weeks. Gestational age can be determined before or after birth. Before birth, your health care provider will use ultrasound to measure the size ...

  6. Genetic causes of transitions from sexual reproduction to asexuality in plants and animals.

    Science.gov (United States)

    Neiman, M; Sharbel, T F; Schwander, T

    2014-07-01

    The persistence of sexual reproduction in the face of competition from asexual invaders is more likely if asexual lineages are produced infrequently or have low fitness. The generation rate and success of new asexual lineages will be influenced by the proximate mechanisms underlying transitions to asexuality. As such, characterization of these mechanisms can help explain the distribution of reproductive modes among natural populations. Here, we synthesize the literature addressing proximate causes of transitions from sexual to asexual reproduction in plants and animals. In cyclical and facultatively asexual taxa, individual mutations can cause obligate asexuality. The evolution of asexuality in obligately sexual groups is more complex, requiring the simultaneous acquisition of two traits generally controlled by different genetic factors: unreduced gamete formation and spontaneous development of unfertilized gametes. At least three 'pre-adaptations' could favour transitions to obligate asexuality in obligate sexuals. First, linkage among loci affecting separate key components of asexuality facilitates its spread, with evidence for these linkage blocks in plants. Second, asexuality should evolve more readily in haplodiploids; support for this hypothesis comes from two examples where a single locus causes transitions to asexuality. Third, standing genetic variation for the production of unreduced gametes could facilitate transitions to asexuality, but whether the ability to produce unreduced gametes contributes to the evolution of obligate asexuality remains unclear. We close by reviewing the associations between asexuality, hybridization and polyploidy, and argue that current data suggest that hybridization is more likely to play a causal role in transitions to asexuality than polyploidy.

  7. Asexual Reproduction in Holothurians

    OpenAIRE

    Igor Yu. Dolmatov

    2014-01-01

    Aspects of asexual reproduction in holothurians are discussed. Holothurians are significant as fishery and aquaculture items and have high commercial value. The last review on holothurian asexual reproduction was published 18 years ago and included only 8 species. An analysis of the available literature shows that asexual reproduction has now been confirmed in 16 holothurian species. Five additional species are also most likely capable of fission. The recent discovery of new fissiparous holot...

  8. Mutation-selection balance and mixed mating with asexual reproduction.

    Science.gov (United States)

    Marriage, Tara N; Orive, Maria E

    2012-09-07

    The effects of asexual reproduction on both the number of deleterious mutations per gamete and the mean fitness under mutation-selection balance are investigated. We use two simulation models, considering both finite and infinite populations. The two models incorporate asexual reproduction with varying levels of outcrossing and selfing, degrees of dominance and selection coefficients. The values for mean fitness and number of deleterious mutations per gamete are compared within and among finite and infinite populations to identify the effect of asexual reproduction on levels of load, and how asexual reproduction may interact with genetic drift (population size). Increasing asexual reproduction resulted in an increase in mean fitness and a decrease in the average number of deleterious mutations per gamete for both nearly recessive and additive alleles in both the infinite and finite simulations. Increased mean fitness with increasing asexuality is possibly due to two interacting forces: a greater opportunity for selection to act on heterozygous versus homozygous mutations and the shielding of a proportion of the population from meiotic mutations due to asexual reproduction. The results found here highlight the need to consider asexual reproduction along with mixed mating in models of genetic load and mutation-selection balance.

  9. Asexual reproduction in holothurians.

    Science.gov (United States)

    Dolmatov, Igor Yu

    2014-01-01

    Aspects of asexual reproduction in holothurians are discussed. Holothurians are significant as fishery and aquaculture items and have high commercial value. The last review on holothurian asexual reproduction was published 18 years ago and included only 8 species. An analysis of the available literature shows that asexual reproduction has now been confirmed in 16 holothurian species. Five additional species are also most likely capable of fission. The recent discovery of new fissiparous holothurian species indicates that this reproduction mode is more widespread in Holothuroidea than previously believed. New data about the history of the discovery of asexual reproduction in holothurians, features of fission, and regeneration of anterior and posterior fragments are described here. Asexual reproduction is obviously controlled by the integrated systems of the organism, primarily the nervous system. Special molecular mechanisms appear to determine the location where fission occurs along the anterior-posterior axis of the body. Alteration of the connective tissue strength of the body wall may play an important role during fission of holothurians. The basic mechanism of fission is the interaction of matrix metalloproteinases, their inhibitors, and enzymes forming cross-link complexes between fibrils of collagen. The population dynamics of fissiparous holothurians are discussed.

  10. LAPAROSCOPIC CHOLECYSTECTOMY AT THE AGA KHAN ...

    African Journals Online (AJOL)

    hi-tech

    2000-04-04

    Apr 4, 2000 ... After initial proper training, a unit to perform this procedure was set up at the Aga Khan ... and confidence developed, the registrar and senior house officer working in our unit ... obesity was no contraindication. We followed the ...

  11. Male sterility in triploid dandelions: asexual females vs. asexual hermaphrodites.

    Science.gov (United States)

    Meirmans, P G; Den Nijs, J C M; Van Tienderen, P H

    2006-01-01

    Male reproductive output, pollen in plants and sperm in animals has been shown to constitute a substantial cost for many organisms. In parthenogenetic hermaphrodites, selection is therefore expected to reduce the allocation of resources to male reproductive output. However, sustained production of pollen or sperm has been observed in numerous asexual hermaphrodites. We studied the widespread production of pollen by triploid asexual dandelions, Taraxacum sect. Ruderalia, comparing rare male sterile individuals with pollen producing asexuals. We found that individuals can show plasticity in the production of pollen, but that it is nevertheless possible to distinguish between (facultatively) male sterile asexuals and male fertile asexuals. Based on evidence from genetic markers and crosses, we conclude that the male sterility in asexual dandelions is caused by nuclear genes, in contrast to the cytoplasmically inherited male sterility previously found in sexual dandelions. Male sterile lineages did not produce more seeds per flower head, heavier seeds or seeds that were more viable. However, male sterile plants did produce more seed heads and hence more seeds than pollen producing ones, indicating that they were able to reallocate resources toward seed production. Considering the difference in seed production, it remains puzzling that not more asexual dandelions are male sterile.

  12. Coevolution of robustness, epistasis, and recombination favors asexual reproduction.

    Science.gov (United States)

    MacCarthy, Thomas; Bergman, Aviv

    2007-07-31

    The prevalence of sexual reproduction remains one of the most perplexing phenomena in evolutionary biology. The deterministic mutation hypothesis postulates that sexual reproduction will be advantageous under synergistic epistasis, a condition in which mutations cause a greater reduction in fitness when combined than would be expected from their individual effects. The inverse condition, antagonistic epistasis, correspondingly is predicted to favor asexual reproduction. To assess this hypothesis, we introduce a finite population evolutionary process that combines a recombination modifier formalism with a gene-regulatory network model. We demonstrate that when reproductive mode and epistasis are allowed to coevolve, asexual reproduction outcompetes sexual reproduction. In addition, no correlation is found between the level of synergistic epistasis and the fixation time of the asexual mode. However, a significant correlation is found between the level of antagonistic epistasis and asexual mode fixation time. This asymmetry can be explained by the greater reduction in fitness imposed by sexual reproduction as compared with asexual reproduction. Our findings present evidence and suggest plausible explanations that challenge both the deterministic mutation hypothesis and recent arguments asserting the importance of emergent synergistic epistasis in the maintenance of sexual reproduction.

  13. Stories about asexuality: a qualitative study on asexual women.

    Science.gov (United States)

    Van Houdenhove, Ellen; Gijs, Luk; T'Sjoen, Guy; Enzlin, Paul

    2015-01-01

    This study aimed to explore how asexual women experience their asexual identity, sexuality, and relationships. The authors recruited participants through the Asexuality Visibility and Education Network's website and posts on several health- and lifestyle-related websites. Interviewees were 9 women between 20 and 42 years of age. Data were collected through semi-structured interviews and analyzed using interpretative phenomenological analysis. The authors discuss 3 main themes that arose from the data: coming to an (a)sexual identity, experiencing physical intimacy and sexuality, and experiencing love and relationships. Participants described how they have always felt different and how they experienced their process of coming out. The authors found a great variation in the experience of (a) sex and physical intimacy and (b) love and relationships. Engaging in sexual behavior was mainly based on a willingness to comply with partner wishes. Whereas some longed for a relationship, aromantic asexual women did not. Some participants separated love from sex. Theoretical and clinical implications of these findings are discussed.

  14. A population of sexual Daphnia pulex resists invasion by asexual clones.

    Science.gov (United States)

    Innes, David J; Ginn, Michael

    2014-08-07

    Asexual reproduction avoids the costs associated with sex, predicting that invading asexual clones can quickly replace sexual populations. Daphnia pulex populations in the Great Lakes area are predominately asexual, but the elimination of sexual populations by invading clones is poorly understood. Asexual clones were detected at low frequency in one rare sexual population in 1995, with some increase in frequency during 2003 and 2004. However, these clones remained at low frequency during further yearly sampling (2005-2013) with no evidence that the resident sexual population was in danger of elimination. There was evidence for hybridization between rare males produced by asexual clones and sexual females with the potential to produce new asexual genotypes and spread the genetic factors for asexuality. In a short-term laboratory competition experiment, the two most common asexual clones did not increase in frequency relative to a genetically diverse sexual population due in part to a greater investment in diapausing eggs that trades-off current population growth for increased contribution to the egg bank. Our results suggest that a successful invasion can be prolonged, requiring a combination of clonal genotypes with high fitness, persistence of clones in the egg bank and negative factors affecting the sexual population such as inbreeding depression resulting from population bottlenecks.

  15. Epigenetic variation in asexually reproducing organisms

    NARCIS (Netherlands)

    Verhoeven, K.J.F.; Preite, V.

    2014-01-01

    The role that epigenetic inheritance can play in adaptation may differ between sexuals and asexuals because (1) the dynamics of adaptation differ under sexual and asexual reproduction and the opportunities offered by epigenetic inheritance may affect these dynamics differently; and (2) in asexual re

  16. Constraints on the evolution of asexual reproduction.

    Science.gov (United States)

    Engelstädter, Jan

    2008-11-01

    Sexual reproduction is almost ubiquitous among multicellular organisms even though it entails severe fitness costs. To resolve this apparent paradox, an extensive body of research has been devoted to identifying the selective advantages of recombination that counteract these costs. Yet, how easy is it to make the transition to asexual reproduction once sexual reproduction has been established for a long time? The present review approaches this question by considering factors that impede the evolution of parthenogenesis in animals. Most importantly, eggs need a diploid chromosome set in most species in order to develop normally. Next, eggs may need to be activated by sperm, and sperm may also contribute centrioles and other paternal factors to the zygote. Depending on how diploidy is achieved mechanistically, further problems may arise in offspring that stem from 'inbreeding depression' or inappropriate sex determination systems. Finally, genomic imprinting is another well-known barrier to the evolution of asexuality in mammals. Studies on species with occasional, deficient parthenogenesis indicate that the relative importance of these constraints may vary widely. The intimate evolutionary relations between haplodiploidy and parthenogenesis as well as implications for the clade selection hypothesis of the maintenance of sexual reproduction are also discussed.

  17. Coevolution of robustness, epistasis, and recombination favors asexual reproduction

    OpenAIRE

    MacCarthy, Thomas; Bergman, Aviv

    2007-01-01

    The prevalence of sexual reproduction remains one of the most perplexing phenomena in evolutionary biology. The deterministic mutation hypothesis postulates that sexual reproduction will be advantageous under synergistic epistasis, a condition in which mutations cause a greater reduction in fitness when combined than would be expected from their individual effects. The inverse condition, antagonistic epistasis, correspondingly is predicted to favor asexual reproduction. To assess this hypothe...

  18. Screening strategies for gestational diabetes mellitus at the Aga ...

    African Journals Online (AJOL)

    Screening strategies for gestational diabetes mellitus at the Aga Khan University ... both strategies and the prevalence of risk factors for gestational diabetes. ... significant for fasting glucose levels (Pearson correlation coefficient, r = -0.06, ...

  19. Asexual reproduction: genetics and evolutionary aspects.

    Science.gov (United States)

    de Meeûs, T; Prugnolle, F; Agnew, P

    2007-06-01

    Reproduction is essential to all organisms if they are to contribute to the next generation. There are various means and ways of achieving this goal. This review focuses on the role of asexual reproduction for eukaryotic organisms and how its integration in a life cycle can influence their population genetics and evolution. An important question for evolutionary biologists as to why some organisms reproduce sexually, as opposed to asexually, is addressed. We also discuss the economic and medical importance of asexual organisms.

  20. Public goods dilemma in asexual ant societies.

    Science.gov (United States)

    Dobata, Shigeto; Tsuji, Kazuki

    2013-10-01

    Cooperation in biological, social, and economic groups is underpinned by public goods that are generated by group members at some personal cost. Theory predicts that public goods will be exploited by cheaters who benefit from the goods by not paying for them, thereby leading to the collapse of cooperation. This situation, described as the "public goods dilemma" in game theory, makes the ubiquity of cooperation a major evolutionary puzzle. Despite this generalization, the demonstration of genetic background and fitness effects of the public goods dilemma has been limited to interactions between viruses and between cells, and thus its relevance at higher levels of organismal complexity is still largely unexplored. Here we provide experimental evidence for the public goods dilemma in a social insect, the ant Pristomyrmex punctatus. In this species, all workers are involved in both asexual reproduction and cooperative tasks. Genetic cheaters infiltrate field colonies, reproducing more than the workers but shunning cooperative tasks. In laboratory experiments, cheaters outcompeted coexisting workers in both survival and reproduction, although a group composed only of cheaters failed to produce offspring. The operations of the public goods dilemma in P. punctatus showed a remarkable convergence with those in microbial societies, not only in fitness consequences but also in behavioral mechanisms. Our study reinforces the evolutionary impact of cheaters on diverse cooperative systems in the laboratory and in the field.

  1. Asexual Plant Reproduction. Agricultural Lesson Plans.

    Science.gov (United States)

    Southern Illinois Univ., Carbondale. Dept. of Agricultural Education and Mechanization.

    These lesson plans are intended for use in conducting classes on asexual plant reproduction. Presented first are an attention step/problem statement and a series of questions and answers designed to convey general information about asexual plant reproduction/propagation. The following topics are among those discussed: plant reproduction methods,…

  2. KONFLIK LINGKUNGAN DI KAMPUNG AGAS, TANJUNG UMA, BATAM (Environmental Conflict in Kampung Agas, Tanjung Uma, Batam

    Directory of Open Access Journals (Sweden)

    Saprial Saprial

    2004-11-01

    Full Text Available ABSTRAK Perkembangan kota Batam sebagai kawasan industri, perdagangan, pelabuhan, dan pariwisata, membawa tidak saja dampak positip, melainkan juga dampak negatif. Salah satu dampak negatif yang muncul adalah konffik lingkungan dalam bentuk pencemaran air di sungai Jodoh yang menganggu pemukiman liar di Kampung Agas, Tanjung Uma. Penelitian ini bertujuan untuk mengkaji akar masalah konflik dan resolusinya. Penelitian ini merupakan studi deskriptif-kualitatip, dengan data yang dikumpulkan melalui wawancara mendalam dengan pihak-pihak yang terlibat dalam konflik. Penelitian ini menemukan bahwa akar masalah konffik adalah konflik spasial antara permukiman liar dan pembangunan ruko yang menimbulkan limbah di sekitar permukiman liar. Tidak dibangunnya IPAL memicu protes warga di permukiman liar dan terjadilah konflik. Penelitian ini melihat bahwa penyelesaian konflik dalam bentuk kompensasi atau “sagu hati" tidak menyelesaikan akar masalah konflik. Walaupun begitu, penyelesaian ini dipandang oleh pihak-pihak yang berkonflik sebagai hasil mufakat yang dimungkinkan untuk menghindari konflik sosial yang lebih besar. Penelitian ini juga menemukan bahwa bentuk penyelesaian konflik melalui musyawarah dan mufakat dapat dilakukan secara efektif sejauh ada mediator yang dipercaya oleh pihak-pihak yang bersengketa.   ABSTRACT The development of Batam City as an area for industry, trade, ship transit, and tourism activities brings not only positive impacts, but negative impact as well. One of the negative impacts is environmental conflict in the form of water pollution in Sei Jodoh downstream which affected informal settlement in Kampung Agas, Tanjung Uma. This research aimed to study the roots of the conflict and evaluated the resolution. It adopted a descriptive, qualitative research method. Data were collected through in-depth interviews with parties involved in the conflict. The research founded that the root causes of the environmental conflict was the

  3. Sexual reproduction with variable mating systems can resist asexuality in a rock-paper-scissors dynamics.

    Science.gov (United States)

    Carranza, Juan; Polo, Vicente

    2015-07-01

    While sex can be advantageous for a lineage in the long term, we still lack an explanation for its maintenance with the twofold cost per generation. Here we model an infinite diploid population where two autosomal loci determine, respectively, the reproductive mode, sexual versus asexual and the mating system, polygynous (costly sex) versus monogamous (assuming equal contribution of parents to offspring, i.e. non-costly sex). We show that alleles for costly sex can spread when non-costly sexual modes buffer the interaction between asexual and costly sexual strategies, even without twofold benefit of recombination with respect to asexuality. The three interacting strategies have intransitive fitness relationships leading to a rock-paper-scissors dynamics, so that alleles for costly sex cannot be eliminated by asexuals in most situations throughout the parameter space. Our results indicate that sexual lineages with variable mating systems can resist the invasion of asexuals and allow for long-term effects to accumulate, thus providing a solution to the persisting theoretical question of why sex was not displaced by asexuality along evolution.

  4. Sexual reproduction with variable mating systems can resist asexuality in a rock–paper–scissors dynamics

    Science.gov (United States)

    Carranza, Juan; Polo, Vicente

    2015-01-01

    While sex can be advantageous for a lineage in the long term, we still lack an explanation for its maintenance with the twofold cost per generation. Here we model an infinite diploid population where two autosomal loci determine, respectively, the reproductive mode, sexual versus asexual and the mating system, polygynous (costly sex) versus monogamous (assuming equal contribution of parents to offspring, i.e. non-costly sex). We show that alleles for costly sex can spread when non-costly sexual modes buffer the interaction between asexual and costly sexual strategies, even without twofold benefit of recombination with respect to asexuality. The three interacting strategies have intransitive fitness relationships leading to a rock–paper–scissors dynamics, so that alleles for costly sex cannot be eliminated by asexuals in most situations throughout the parameter space. Our results indicate that sexual lineages with variable mating systems can resist the invasion of asexuals and allow for long-term effects to accumulate, thus providing a solution to the persisting theoretical question of why sex was not displaced by asexuality along evolution. PMID:26587254

  5. Asexual reproduction : genetics and evolutionary aspects

    OpenAIRE

    DE Meeûs, Thierry; Prugnolle, Franck; Agnew, Philip

    2007-01-01

    Reproduction is essential to all organisms if they are to contribute to the next generation. There are various means and ways of achieving this goal. This review focuses on the role of asexual reproduction for eukaryotic organisms and how its integration in a life cycle can influence their population genetics and evolution. An important question for evolutionary biologists as to why some organisms reproduce sexually, as opposed to asexually, is addressed. We also discuss the economic and medi...

  6. Aga sellepärast, et on po... / Aleksandr Astrov

    Index Scriptorium Estoniae

    Astrov, Aleksandr

    2005-01-01

    Arutledes venekeelse valija hääletuskäitumise ümber juhib autor tähelepanu, et Eestis sätestab üks konkreetne seadus venelastele valimisõiguse, andes neile reaalse poliitilise jõu, teine aga piirab nende juurdepääsu ainult keele kaudu ligipääsetavatele eetikaressurssidele, mis võimaldaksid teha teadlikku valikut

  7. Revisiting Reuter: Symbolic and material economies in Bali aga society

    Directory of Open Access Journals (Sweden)

    Alexander R. Cuthbert

    2017-05-01

    Full Text Available The objective of this paper is to analyse Thomas Reuter’s seminal text The Custodians of the Sacred Mountains and to discuss some of the theoretical and other issues that flow from the reading. Indirectly it is also intended to assist many local scholars who find the text somewhat impenetrable, let alone making connections to its extensive implications. The book is the second study to emerge that covers the regional basis for the Bali Aga, the first being that of Wälty (1997. The text is one of a kind - erudite, complex and intellectually challenging. The paper begins with historical interventions since the status economy of Bali Aga is wholly dependent on a mythical past. Next, the use of theory, focussing on anthropology and Bali studies is discussed to place Reuter’s work in context. Then his basic concepts are analysed, those of precedence, status, and representation. Subsequently, we focus on place and space since geography is a defining feature of Bali Aga. Finally the mental (symbolic and material (political economy dimensions are contrasted with the observation that omission of any consideration of the latter weakens an otherwise seminal work.

  8. Environmental challenges improve resource utilization for asexual reproduction and maintenance in hydra.

    Science.gov (United States)

    Schaible, Ralf; Ringelhan, Felix; Kramer, Boris H; Miethe, Tanja

    2011-10-01

    Variation in life history can reflect genetic differences, and may be caused by environmental effects on phenotypes. Understanding how these two sources of life history variation interact to express an optimal allocation of resources in a changing environment is central to life history theory. This study addresses variation in the allocation of resources to asexual reproduction and to maintenance of Hydra magnipapillata in relation to differences in temperature and food availability. Hydra is a non-senescent, persistent species with primarily clonal reproduction. We recorded changes in budding rate and mean survival under starvation, which indicate changes in the allocation of resources to asexual reproduction and maintenance. In constant conditions we observed a clear trade-off between asexual reproduction and maintenance, where budding increased linearly with food intake while starvation survival stayed rather constant. In contrast, an environment with fluctuations in temperature or food availability promotes maintenance and increases the survival chances of hydra under starvation. Surprisingly, asexual reproduction also tends to be positively affected by fluctuating environmental conditions, which suggests that in this case there is no clear trade-off between asexual reproduction and maintenance in hydra. Environmental stresses have a beneficial impact on the fitness-related phenotypical traits of the basal metazoan hydra. The results indicate that, if the stress occurs in hormetic doses, variable stressful and fluctuating environments can be salutary for hydra. A closer examination of this dynamic can therefore enable us to develop a deeper understanding of the evolution of aging and longevity.

  9. Adaptive molecular evolution of a defence gene in sexual but not functionally asexual evening primroses.

    Science.gov (United States)

    Hersch-Green, E I; Myburg, H; Johnson, M T J

    2012-08-01

    Theory predicts that sexual reproduction provides evolutionary advantages over asexual reproduction by reducing mutational load and increasing adaptive potential. Here, we test the latter prediction in the context of plant defences against pathogens because pathogens frequently reduce plant fitness and drive the evolution of plant defences. Specifically, we ask whether sexual evening primrose plant lineages (Onagraceae) have faster rates of adaptive molecular evolution and altered gene expression of a class I chitinase, a gene implicated in defence against pathogens, than functionally asexual evening primrose lineages. We found that the ratio of amino acid to silent substitutions (K(a) /K(s) = 0.19 vs. 0.11 for sexual and asexual lineages, respectively), the number of sites identified to be under positive selection (four vs. zero for sexual and asexual lineages, respectively) and the expression of chitinase were all higher in sexual than in asexual lineages. Our results are congruent with the conclusion that a loss of sexual recombination and segregation in the Onagraceae negatively affects adaptive structural and potentially regulatory evolution of a plant defence protein.

  10. Queen succession through asexual reproduction in termites.

    Science.gov (United States)

    Matsuura, Kenji; Vargo, Edward L; Kawatsu, Kazutaka; Labadie, Paul E; Nakano, Hiroko; Yashiro, Toshihisa; Tsuji, Kazuki

    2009-03-27

    The evolution and maintenance of sexual reproduction may involve important tradeoffs because asexual reproduction can double an individual's contribution to the gene pool but reduces diversity. Moreover, in social insects the maintenance of genetic diversity among workers may be important for colony growth and survival. We identified a previously unknown termite breeding system in which both parthenogenesis and sexual reproduction are conditionally used. Queens produce their replacements asexually but use normal sexual reproduction to produce other colony members. These findings show how eusociality can lead to extraordinary reproductive systems and provide important insights into the advantages and disadvantages of sex.

  11. Bounding The Rate of Adaptation In A Large Asexually Reproducing Population With Fast Mutation Rates

    CERN Document Server

    Kelly, Michael

    2011-01-01

    We consider a model of asexually reproducing individuals. The birth and death rates of the individuals are affected by a fitness parameter. The rate of mutations that cause the fitnesses to change is proportional to the population size, $N$. The mutations may be either beneficial or deleterious. In a paper by Yu, Etheridge and Cuthbertson (2009) it was shown that the average rate at which the mean fitness increases in this model is bounded below by $\\log^{1-\\delta} N$ for any $\\delta > 0$. We achieve an upper bound on the average rate at which the mean fitness increases of $O(\\log N/\\log \\log N)$.

  12. Environmental factors influencing asexual reproductive processes in echinoderms

    OpenAIRE

    Mladenov, Pv

    1996-01-01

    This review provides a brief update of the occurrence and adaptive significance of asexual reproduction in echinoderms. It then focuses on the state of knowledge of biotic and abiotic factors that influence asexual processes in this group, particularly factors that may play a role in regulating the expression and relative proportion of asexual versus sexual phenotypes within populations of species, as well as factors modulating and triggering asexual processes. The information presented in th...

  13. Molecular Evidence for Ancient Asexuality in Timema Stick Insects

    NARCIS (Netherlands)

    Schwander, Tanja; Henry, Lee; Crespi, Bernard J.

    2011-01-01

    Asexuality is rare in animals in spite of its apparent advantage relative to sexual reproduction, indicating that it must be associated with profound costs [1-9]. One expectation is that reproductive advantages gained by new asexual lineages will be quickly eroded over time [3, 5-7]. Ancient asexual

  14. Molecular Evidence for Ancient Asexuality in Timema Stick Insects

    NARCIS (Netherlands)

    Schwander, Tanja; Henry, Lee; Crespi, Bernard J.

    2011-01-01

    Asexuality is rare in animals in spite of its apparent advantage relative to sexual reproduction, indicating that it must be associated with profound costs [1-9]. One expectation is that reproductive advantages gained by new asexual lineages will be quickly eroded over time [3, 5-7]. Ancient asexual

  15. Independently evolving species in asexual bdelloid rotifers.

    Directory of Open Access Journals (Sweden)

    Diego Fontaneto

    2007-04-01

    Full Text Available Asexuals are an important test case for theories of why species exist. If asexual clades displayed the same pattern of discrete variation as sexual clades, this would challenge the traditional view that sex is necessary for diversification into species. However, critical evidence has been lacking: all putative examples have involved organisms with recent or ongoing histories of recombination and have relied on visual interpretation of patterns of genetic and phenotypic variation rather than on formal tests of alternative evolutionary scenarios. Here we show that a classic asexual clade, the bdelloid rotifers, has diversified into distinct evolutionary species. Intensive sampling of the genus Rotaria reveals the presence of well-separated genetic clusters indicative of independent evolution. Moreover, combined genetic and morphological analyses reveal divergent selection in feeding morphology, indicative of niche divergence. Some of the morphologically coherent groups experiencing divergent selection contain several genetic clusters, in common with findings of cryptic species in sexual organisms. Our results show that the main causes of speciation in sexual organisms, population isolation and divergent selection, have the same qualitative effects in an asexual clade. The study also demonstrates how combined molecular and morphological analyses can shed new light on the evolutionary nature of species.

  16. Extreme genetic diversity in asexual grass thrips populations.

    Science.gov (United States)

    Fontcuberta García-Cuenca, A; Dumas, Z; Schwander, T

    2016-05-01

    The continuous generation of genetic variation has been proposed as one of the main factors explaining the maintenance of sexual reproduction in nature. However, populations of asexual individuals may attain high levels of genetic diversity through within-lineage diversification, replicate transitions to asexuality from sexual ancestors and migration. How these mechanisms affect genetic variation in populations of closely related sexual and asexual taxa can therefore provide insights into the role of genetic diversity for the maintenance of sexual reproduction. Here, we evaluate patterns of intra- and interpopulation genetic diversity in sexual and asexual populations of Aptinothrips rufus grass thrips. Asexual A. rufus populations are found throughout the world, whereas sexual populations appear to be confined to few locations in the Mediterranean region. We found that asexual A. rufus populations are characterized by extremely high levels of genetic diversity, both in comparison with their sexual relatives and in comparison with other asexual species. Migration is extensive among asexual populations over large geographic distances, whereas close sexual populations are strongly isolated from each other. The combination of extensive migration with replicate evolution of asexual lineages, and a past demographic expansion in at least one of them, generated high local clone diversities in A. rufus. These high clone diversities in asexual populations may mimic certain benefits conferred by sex via genetic diversity and could help explain the extreme success of asexual A. rufus populations.

  17. Who runs fastest in an adaptive landscape: sexual versus asexual reproduction

    Science.gov (United States)

    Holmström, Kerstin; Jensen, Henrik Jeldtoft

    2004-06-01

    We compare the speed with which a sexual, respectively, an asexual, population is able to respond to a biased selective pressure. Our model focuses on the Weismann hypothesis that the extra variation caused by crossing-over and recombination during sexual reproduction allows a sexual population to adapt faster. We find, however, that the extra variation amongst the progeny produced during sexual reproduction for most model parameters is unable to overcome the effect that parents with a high individual fitness in general must mate with individuals of lower individual fitness resulting in a moderate reproductive fitness for the pair.

  18. Comparison of Patent Claim Construction between Netherlands and Germany on Basis of AGA v. Occlutech

    NARCIS (Netherlands)

    Tsoutsanis, A.; Kau, C.

    2013-01-01

    This article provides a brief overview on how the Dutch and German courts interpret the claims of a patent. It briefly compares each national approach on the basis of the recent AGA v Occlutech litigation in both countries. The dispute between AGA and Occlutech involved socalled ‘‘occluders’’, a

  19. Comparison of Patent Claim Construction between Netherlands and Germany on Basis of AGA v. Occlutech

    NARCIS (Netherlands)

    Tsoutsanis, A.; Kau, C.

    2013-01-01

    This article provides a brief overview on how the Dutch and German courts interpret the claims of a patent. It briefly compares each national approach on the basis of the recent AGA v Occlutech litigation in both countries. The dispute between AGA and Occlutech involved socalled ‘‘occluders’’, a col

  20. Dynamics of asexual reproduction in flatworms

    Science.gov (United States)

    Schoetz, Eva-Maria; Talbot, Jared; Dunkel, Joern

    2010-03-01

    Planarians (flatworms) are one of the simplest bilaterally symmetric organisms and famous for their extraordinary regenerative capabilities. One can cut a worm in 100 pieces and after a few weeks one obtains 100 new worms that have reconstructed their entire body, including a central nervous system. This amazing regenerative capability is due to a population of stem cells distributed throughout the planarian body. These stem cells do not only allow the worms to heal without scarring after wounding, they also allow for asexual reproduction: Planarians can split themselves in two, and then regenerate the missing body parts within about a week. Naively, one would think that this kind of asexual reproduction could be captured by simple models that describe cell growth in bacteria or other lower organisms. However, we find that there is much more to the story by monitoring >15 generations of many individuals, as well as the long-term behavior (> 9 months) of worm populations under different environmental conditions, such as population density, temperature, and feeding frequency. Surprisingly, we observe that reproduction decreases with increasing food supply, opposite to the relationship between food and reproduction in other asexually reproducing organisms (e.g. bacteria, yeast), and causing obese worms. Finally, our data allows us to address the question of aging in an organism that is thought to be ``forever young''.

  1. On the Genealogy of Asexual Diploids

    Science.gov (United States)

    Lam, Fumei; Langley, Charles H.; Song, Yun S.

    Given molecular genetic data from diploid individuals that, at present, reproduce mostly or exclusively asexually without recombination, an important problem in evolutionary biology is detecting evidence of past sexual reproduction (i.e., meiosis and mating) and recombination (both meiotic and mitotic). However, currently there is a lack of computational tools for carrying out such a study. In this paper, we formulate a new problem of reconstructing diploid genealogies under the assumption of no sexual reproduction or recombination, with the ultimate goal being to devise genealogy-based tools for testing deviation from these assumptions. We first consider the infinite-sites model of mutation and develop linear-time algorithms to test the existence of an asexual diploid genealogy compatible with the infinite-sites model of mutation, and to construct one if it exists. Then, we relax the infinite-sites assumption and develop an integer linear programming formulation to reconstruct asexual diploid genealogies with the minimum number of homoplasy (back or recurrent mutation) events. We apply our algorithms on simulated data sets with sizes of biological interest.

  2. Do clones degenerate over time? Explaining the genetic variability of asexuals through population genetic models

    Directory of Open Access Journals (Sweden)

    Drozd Pavel

    2011-03-01

    Full Text Available Abstract Background Quest for understanding the nature of mechanisms governing the life span of clonal organisms lasts for several decades. Phylogenetic evidence for recent origins of most clones is usually interpreted as proof that clones suffer from gradual age-dependent fitness decay (e.g. Muller's ratchet. However, we have shown that a neutral drift can also qualitatively explain the observed distribution of clonal ages. This finding was followed by several attempts to distinguish the effects of neutral and non-neutral processes. Most recently, Neiman et al. 2009 (Ann N Y Acad Sci.:1168:185-200. reviewed the distribution of asexual lineage ages estimated from a diverse array of taxa and concluded that neutral processes alone may not explain the observed data. Moreover, the authors inferred that similar types of mechanisms determine maximum asexual lineage ages in all asexual taxa. In this paper we review recent methods for distinguishing the effects of neutral and non-neutral processes and point at methodological problems related with them. Results and Discussion We found that contemporary analyses based on phylogenetic data are inadequate to provide any clear-cut answer about the nature and generality of processes affecting evolution of clones. As an alternative approach, we demonstrate that sequence variability in asexual populations is suitable to detect age-dependent selection against clonal lineages. We found that asexual taxa with relatively old clonal lineages are characterised by progressively stronger deviations from neutrality. Conclusions Our results demonstrate that some type of age-dependent selection against clones is generally operational in asexual animals, which cover a wide taxonomic range spanning from flatworms to vertebrates. However, we also found a notable difference between the data distribution predicted by available models of sequence evolution and those observed in empirical data. These findings point at the

  3. Origins of asexuality in Bryobia mites (Acari: Tetranychidae

    Directory of Open Access Journals (Sweden)

    Menken Steph BJ

    2008-05-01

    Full Text Available Abstract Background Obligate asexual reproduction is rare in the animal kingdom. Generally, asexuals are considered evolutionary dead ends that are unable to radiate. The phytophagous mite genus Bryobia contains a large number of asexual species. In this study, we investigate the origin and evolution of asexuality using samples from 111 populations in Europe, South Africa and the United States, belonging to eleven Bryobia species. We also examine intraspecific clonal diversity for one species, B. kissophila, by genotyping individuals from 61 different populations. Knowledge on the origin of asexuality and on clonal diversity can contribute to our understanding of the paradox of sex. Results The majority (94% of 111 sampled populations reproduces asexually. Analysis of part of nuclear 28S rDNA shows that these asexuals do not form a monophyletic clade. Analysis of the mitochondrial COI region shows that intraspecific variation is extensive (up to 8.8%. Within B. kissophila, distinct clades are found, which are absent at the nuclear 28S rDNA level. Moreover, paraphyletic patterns are found at the mitochondrial DNA. Conclusion Asexuality is widespread in the genus Bryobia, signifying that some animal taxa do contain a high number of asexuals. We argue that asexuality originated multiple times within Bryobia. Wolbachia bacteria cause asexuality in at least two Bryobia species and may have infected different species independently. The high intraspecific clonal diversity and the patterns of paraphyly at the mitochondrial DNA in B. kissophila might be explained by a high mutation fixation rate and past hybridization events. Reproductive parasites like Wolbachia and Cardinium might influence these processes. We discuss the role these bacteria could play in the evolutionary success of asexual species.

  4. Asexual and sexual reproductive strategies in clonal plants

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yufen; ZHANG Dayong

    2007-01-01

    Most plants can reproduce both sexually and asexually (or vegetatively),and the balance between the two reproductive modes may vary widely between and within species.Extensive clonal growth may affect the evolution of life history traits in many ways.First,in some clonal species,sexual reproduction and sex ratio vary largely among populations.Variation in sexual reproduction may strongly affect plant's adaptation to local environments and the evolution of the geographic range.Second,clonal growth can increase floral display,and thus pollinator attraction,while it may impose serious constraints and evolutionary challenges on plants through geitonogamy that may strongly influence pollen dispersal.Geitonogamous pollination can bring a cost to plant fitness through both female and male functions.Some co-evolutionary interactions,therefore,may exist between the spatial structure and the mating behavior of clonal plants.Finally,a trade-off may exist between sexual reproduction and clonal growth.Resource allocation to the two reproductive modes may depend on environmental conditions,competitive dominance,life span,and genetic factors.If different reproductive modes represent adaptive strategies for plants in different environments,we expect that most of the resources should be allocated to sexual reproduction in habitats with fluctuating environmental conditions and strong competition,while clonal growth should be dominant in stable habitats.Yet we know little about the consequence of natural selection on the two reproductive modes and factors which control the balance of the two reproductive modes.Future studies should investigate the reproductive strategies of clonal plants simultaneously from both sexual and asexual perspectives.

  5. Implicit and Explicit Attitudes Toward Sex and Romance in Asexuals.

    Science.gov (United States)

    Bulmer, Maria; Izuma, Keise

    2017-03-31

    Despite the recent surge of interest in sexuality, asexuality has remained relatively underresearched. Distinct from abstinence or chastity, asexuality refers to a lack of sexual attraction toward others. Past research suggests asexuals have negative attitudes toward sex, though no research has examined implicit attitudes. While preliminary evidence suggests that many asexuals are interested in engaging in romantic relationships, these attitudes have yet to be examined thoroughly, implicitly, or compared with a control group. This study investigated explicit and implicit attitudes toward sex and romance in a group of asexuals (N = 18, age M = 21.11) and a group of controls (N = 27, age M = 21.81), using the Asexuality Identification Scale (AIS), the Triangular Love Scale (TLS), semantic differentials, an Implicit Association Task (IAT), and two Single Category IATs. It was found that asexuals exhibited more negative explicit and implicit attitudes toward sex, as well as more negative explicit attitudes toward romance, relative to controls. There was no significant difference between groups on implicit romantic attitudes. Moreover, aromantic asexuals demonstrated significantly more negative explicit attitudes toward romance than romantic asexuals, though there was no significant difference between groups on implicit measures. Explanations and implications of these findings are discussed.

  6. [Asexual reproduction of planarians: metric studies].

    Science.gov (United States)

    Sheĭman, I M; Sedel'nikov, Z V; Shkutin, M F; Kreshchenko, N D

    2006-01-01

    A relationship was studied between fission and restoration of body and its individual parts under different experimental conditions in planarians of the Dugesia tigrina asexual race. The body and its fragments were studied morphomterically. After fission, the growth of planarians demonstrated topographic differences. The separated tail fragments and postpharyngeal area, in which the zone of fission is formed, were growing at the highest rate. More active growth was also noted over the long body axis. Fission and growth were more active in isolated planarians, as compared to those kept in groups.

  7. On the asexual reproduction of Plagiochila pluma Steph.

    OpenAIRE

    Piippo, Sinikka

    1992-01-01

    Four types of asexual reproduction in Plagiochila and the Plagiochilaceae are known: propagules, caducous leaves, gemmae and cladia. Plagiochila pluma Steph. has caducous leaves and teeth with regenerants. The terms for asexual reproduction modes in liverworts are briefly discussed and new definitions proposed.

  8. Deleterious mutation accumulation in asexual Timema stick insects.

    Science.gov (United States)

    Henry, Lee; Schwander, Tanja; Crespi, Bernard J

    2012-01-01

    Sexual reproduction is extremely widespread in spite of its presumed costs relative to asexual reproduction, indicating that it must provide significant advantages. One postulated benefit of sex and recombination is that they facilitate the purging of mildly deleterious mutations, which would accumulate in asexual lineages and contribute to their short evolutionary life span. To test this prediction, we estimated the accumulation rate of coding (nonsynonymous) mutations, which are expected to be deleterious, in parts of one mitochondrial (COI) and two nuclear (Actin and Hsp70) genes in six independently derived asexual lineages and related sexual species of Timema stick insects. We found signatures of increased coding mutation accumulation in all six asexual Timema and for each of the three analyzed genes, with 3.6- to 13.4-fold higher rates in the asexuals as compared with the sexuals. In addition, because coding mutations in the asexuals often resulted in considerable hydrophobicity changes at the concerned amino acid positions, coding mutations in the asexuals are likely associated with more strongly deleterious effects than in the sexuals. Our results demonstrate that deleterious mutation accumulation can differentially affect sexual and asexual lineages and support the idea that deleterious mutation accumulation plays an important role in limiting the long-term persistence of all-female lineages.

  9. Molecular evidence for ancient asexuality in timema stick insects.

    Science.gov (United States)

    Schwander, Tanja; Henry, Lee; Crespi, Bernard J

    2011-07-12

    Asexuality is rare in animals in spite of its apparent advantage relative to sexual reproduction, indicating that it must be associated with profound costs [1-9]. One expectation is that reproductive advantages gained by new asexual lineages will be quickly eroded over time [3, 5-7]. Ancient asexual taxa that have evolved and adapted without sex would be "scandalous" exceptions to this rule, but it is often difficult to exclude the possibility that putative asexuals deploy some form of "cryptic" sex, or have abandoned sex more recently than estimated from divergence times to sexual relatives [10]. Here we provide evidence, from high intraspecific divergence of mitochondrial sequence and nuclear allele divergence patterns, that several independently derived Timema stick-insect lineages have persisted without recombination for more than a million generations. Nuclear alleles in the asexual lineages displayed significantly higher intraindividual divergences than in related sexual species. In addition, within two asexuals, nuclear allele phylogenies suggested the presence of two clades, with sequences from the same individual appearing in both clades. These data strongly support ancient asexuality in Timema and validate the genus as an exceptional opportunity to attack the question of how asexual reproduction can be maintained over long periods of evolutionary time.

  10. Habitat heterogeneity favors asexual reproduction in natural populations of grassthrips.

    Science.gov (United States)

    Lavanchy, Guillaume; Strehler, Marie; Llanos Roman, Maria Noemi; Lessard-Therrien, Malie; Humbert, Jean-Yves; Dumas, Zoé; Jalvingh, Kirsten; Ghali, Karim; Fontcuberta García-Cuenca, Amaranta; Zijlstra, Bart; Arlettaz, Raphaël; Schwander, Tanja

    2016-08-01

    Explaining the overwhelming success of sex among eukaryotes is difficult given the obvious costs of sex relative to asexuality. Different studies have shown that sex can provide benefits in spatially heterogeneous environments under specific conditions, but whether spatial heterogeneity commonly contributes to the maintenance of sex in natural populations remains unknown. We experimentally manipulated habitat heterogeneity for sexual and asexual thrips lineages in natural populations and under seminatural mesocosm conditions by varying the number of hostplants available to these herbivorous insects. Asexual lineages rapidly replaced the sexual ones, independently of the level of habitat heterogeneity in mesocosms. In natural populations, the success of sexual thrips decreased with increasing habitat heterogeneity, with sexual thrips apparently only persisting in certain types of hostplant communities. Our results illustrate how genetic diversity-based mechanisms can favor asexuality instead of sex when sexual lineages co-occur with genetically variable asexual lineages.

  11. Asexuality development among middle aged and older men.

    Directory of Open Access Journals (Sweden)

    Yan-Ping Huang

    Full Text Available OBJECTIVES: To assess erectile function in middle-aged and older men with asexuality status and further analyze their specific reasons for this condition. SUBJECTS AND METHODS: Men who had regular sexual intercourse attempts (sex frequency ≥ 1 time per month were classified into mild erectile dysfunction (ED, moderate to severe ED and non-ED according to International Index of Erectile Function-5, and men having no sexual intercourse attempts for at least 6 months were defined as having an asexuality status. The risk factors associated with ED were collected in a sample of 1,531 Chinese men aged 40 to 80 years, and the self-report reasons for asexuality were recorded in asexual cohort individually. Comparative analyses and multivariate regression models were conducted among these groups. RESULTS: The prevalence rates of ED and asexuality status were 49.9% and 37.2%. The asexuality status group had higher risk factors than the moderate to severe ED group in terms of old age (age ≥ 65, adjusted odds ratio (OR 17.69 versus (Vs. 7.19, diabetes (crude OR: 2.40 Vs. 2.36 and hypertension (crude OR: 1.78 Vs. 1.72. The specific reasons for the asexuality status were "erectile difficulty" (52.9%, "do not care about sexuality" (53.5%", "no longer necessary to have sexuality at this age" (47.7%, "severe stress" (44.4%, "severe fatigue" (26.3% and "masturbation" (26.9%. CONCLUSIONS: Men with an asexual status suffer from higher risk factors for ED than men with moderate to severe ED. The majority of this asexual status could be attributed to a full ED, although the reasons for this transient asexuality also involved sexual attitudes and interests, sexual partners and masturbation.

  12. Origination of asexual plantlets in three species of Crassulaceae.

    Science.gov (United States)

    Guo, Jiansheng; Liu, Hailiang; He, Yangyang; Cui, Xianghuan; Du, Xiling; Zhu, Jian

    2015-03-01

    During asexual plant reproduction, cells from different organs can be reprogrammed to produce new individuals, a process that requires the coordination of cell cycle reactivation with the acquisition of other cellular morphological characteristics. However, the factors that influence the variety of asexual reproduction have not yet been determined. Here, we report on plantlet formation in Kalanchoe daigremontiana, Graptopetalum paraguayense, and Crassula portulacea (Crassulaceae) and analyse the effect of initiating cells on asexual reproduction in these three species. Additionally, the roles of WUSCHEL (WUS) and CUP-SHAPED COTYLEDON 1 (CUC1) in the asexual reproduction of these species were analysed through qRT-PCR. Our results indicated that pre-existing stem cell-like cells at the sites of asexual reproduction were responsible for the formation of plantlets. These cells were arrested in different phases of the cell cycle and showed different cell morphological characteristics and cell counts. The accumulation of auxin and cytokinin at the sites of asexual plantlet formation indicated their important functions, particularly for cell cycle reactivation. These differences may influence the pattern and complexity of asexual reproduction in these Crassulaceae species. Additionally, the dynamic expression levels of CUC1 and WUS may indicate that CUC1 functions in the formation of callus and shoot meristems; whereas, WUS was only associated with shoot induction.

  13. Gonad establishment during asexual reproduction in the annelid Pristina leidyi

    National Research Council Canada - National Science Library

    Özpolat, B Duygu; Bely, Alexandra E

    2015-01-01

    .... We investigated germ line development in the annelid Pristina leidyi, a species that typically reproduces asexually by paratomic fission, intercalating a new tail and head in the middle of the body...

  14. Hybridization and the Origin of Contagious Asexuality in Daphnia pulex

    OpenAIRE

    Xu, Sen; Spitze, Ken; Ackerman, Matthew S.; Ye, Zhiqiang; Bright, Lydia; Keith, Nathan; Jackson, Craig E.; Shaw, Joseph R.; Lynch, Michael

    2015-01-01

    Hybridization plays a potentially important role in the origin of obligate parthenogenesis (OP) in many organisms. However, it remains controversial whether hybridization directly triggers the transition from sexual reproduction to obligate asexuality or a hybrid genetic background enables asexual species to persist. Furthermore, we know little about the specific genetic elements from the divergent, yet still hybridizing lineages responsible for this transition and how these elements are furt...

  15. Chromosome length scaling in haploid, asexual reproduction

    Science.gov (United States)

    de Oliveira, P. M. C.

    2007-02-01

    We study the genetic behaviour of a population formed by haploid individuals which reproduce asexually. The genetic information for each individual is stored along a bit-string (or chromosome) with L bits, where 0-bits represent the wild allele and 1-bits correspond to harmful mutations. Each newborn inherits this chromosome from its parent with a few random mutations: on average a fixed number m of bits are flipped. Selection is implemented according to the number N of 1-bits counted along the individual's chromosome: the smaller N the higher the probability an individual has to survive a new time step. Such a population evolves, with births and deaths, and its genetic distribution becomes stabilized after sufficiently many generations have passed. The question we pose concerns the procedure of increasing L. The aim is to get the same distribution of genetic loads N/L among the equilibrated population, in spite of a larger L. Should we keep the same mutation rate m/L for different values of L? The answer is yes, which intuitively seems to be plausible. However, this conclusion is not trivial, according to our simulation results: the question also involves the population size.

  16. Chromosome length scaling in haploid, asexual reproduction

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, P M C de [Instituto de Fisica, Universidade Federal Fluminense, avenida Litoranea s/n, Boa Viagem, Niteroi 24210-340 (Brazil)

    2007-02-14

    We study the genetic behaviour of a population formed by haploid individuals which reproduce asexually. The genetic information for each individual is stored along a bit-string (or chromosome) with L bits, where 0-bits represent the wild allele and 1-bits correspond to harmful mutations. Each newborn inherits this chromosome from its parent with a few random mutations: on average a fixed number m of bits are flipped. Selection is implemented according to the number N of 1-bits counted along the individual's chromosome: the smaller N the higher the probability an individual has to survive a new time step. Such a population evolves, with births and deaths, and its genetic distribution becomes stabilized after sufficiently many generations have passed. The question we pose concerns the procedure of increasing L. The aim is to get the same distribution of genetic loads N/L among the equilibrated population, in spite of a larger L. Should we keep the same mutation rate m/L for different values of L? The answer is yes, which intuitively seems to be plausible. However, this conclusion is not trivial, according to our simulation results: the question also involves the population size.

  17. Kepemimpinan Lokal dan Kehidupan Sosial Politik Perempuan di Dua Desa Bali Aga Kabupaten Buleleng

    Directory of Open Access Journals (Sweden)

    Ni Wayan Arini

    2015-01-01

    Full Text Available Penelitian ini bertujuan (1 menganalisis strategi pemimpin lokal melibatkan perempuan pada  bidang sosial dan politik dalam institusi keluarga, masyarakat, dan lembaga politik di Desa Julah, Desa Tigawasa  sebagai Desa Bali Aga di Kabupaten Buleleng, (2 menganalisis hambatan dan solusi pemimpin lokal melibatkan perempuan pada bidang sosial politik dalam institusi keluarga, masyarakat dan politik di Desa Julah, Desa Tigawasa  sebagai Desa Bali Aga di Kabupaten Buleleng, dan (3  menganalisis pendidikan politik yang ideal dikehendaki oleh perempuan pascaotonomi di Desa Julah, Desa Tigawasa sebagai Desa Bali Aga di Kabupaten Buleleng. Penelitian ini adalah penelitian etnografis naturalisitik untuk mendeskripsikan secara aktual, faktual, alamiah, dan holistik tentang keterlibatan perempuan dalam bidang sosial politik. Subjek penelitian ini adalah prajuru desa pakraman, kepala desa, tokoh masyarakat, teruna-teruni, PKK, dan anggota masyarakat yang ditentukan secara purposive. Data dikumpulkan dengan prinsip “human instrument”, yaitu peneliti merupakan instrumen peneliti yang utama, di samping menggunakan  kuesioner. Data yang terkumpul dianalisis dengan analisis deskriptif. Hasil penelitian menunjukkan bahwa pemimpin lokal desa prakraman Julah dan  Tigawasa menerapkan beberapa strategi untuk melibatkan perempuan dalam bidang sosial politik. Penerapan strategi ini berjalan lancar, sehingga perempuan memperoleh kesempatan belajar berpolitik melalui berbagai organisasi yang ada di desa. Atas dasar itu, disarankan agar pemimpin lokal memberikan kontribusi terhadap kehidupan sosial politik perempuan di dua Desa Bali Aga di Kabupaten Buleleng dalam upaya memberdayakan perempuan yang berwawasan dan berkeadilan gender.

  18. Antigliadin Antibodies (AGA IgG Are Related to Neurochemistry in Schizophrenia

    Directory of Open Access Journals (Sweden)

    Laura M. Rowland

    2017-06-01

    Full Text Available Inflammation may play a role in schizophrenia; however, subgroups with immune regulation dysfunction may serve as distinct illness phenotypes with potential different treatment and prevention strategies. Emerging data show that about 30% of people with schizophrenia have elevated antigliadin antibodies of the IgG type, representing a possible subgroup of schizophrenia patients with immune involvement. Also, recent data have shown a high correlation of IgG-mediated antibodies between the periphery and cerebral spinal fluid in schizophrenia but not healthy controls, particularly AGA IgG suggesting that these antibodies may be crossing the blood–brain barrier with resulting neuroinflammation. Proton magnetic resonance spectroscopy (MRS is a non-invasive technique that allows the quantification of certain neurochemicals in vivo that may proxy inflammation in the brain such as myoinositol and choline-containing compounds (glycerophosphorylcholine and phosphorylcholine. The objective of this exploratory study was to examine the relationship between serum AGA IgG levels and MRS neurochemical levels. We hypothesized that higher AGA IgG levels would be associated with higher levels of myoinositol and choline-containing compounds (glycerophosphorylcholine plus phosphorylcholine; GPC + PC in the anterior cingulate cortex. Thirty-three participants with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder had blood drawn and underwent neuroimaging using MRS within 9 months. We found that 10/33 (30% had positive AGA IgG (≥20 U similar to previous findings. While there were no significant differences in myoinositol and GPC + PC levels between patients with and without AGA IgG positivity, there were significant relationships between both myoinositol (r = 0.475, p = 0.007 and GPC + PC (r = 0.36, p = 0.045 with AGA IgG levels. This study shows a possible connection of AGA IgG antibodies to putative brain

  19. Biological markers of asexuality: Handedness, birth order, and finger length ratios in self-identified asexual men and women.

    Science.gov (United States)

    Yule, Morag A; Brotto, Lori A; Gorzalka, Boris B

    2014-02-01

    Human asexuality is defined as a lack of sexual attraction to anyone or anything and it has been suggested that it may be best conceptualized as a sexual orientation. Non-right-handedness, fraternal birth order, and finger length ratio (2D:4D) are early neurodevelopmental markers associated with sexual orientation. We conducted an Internet study investigating the relationship between self-identification as asexual, handedness, number of older siblings, and self-measured finger-lengths in comparison to individuals of other sexual orientation groups. A total of 325 asexuals (60 men and 265 women; M age, 24.8 years), 690 heterosexuals (190 men and 500 women; M age, 23.5 years), and 268 non-heterosexuals (homosexual and bisexual; 64 men and 204 women; M age, 29.0 years) completed online questionnaires. Asexual men and women were 2.4 and 2.5 times, respectively, more likely to be non-right-handed than their heterosexual counterparts and there were significant differences between sexual orientation groups in number of older brothers and older sisters, and this depended on handedness. Asexual and non-heterosexual men were more likely to be later-born than heterosexual men, and asexual women were more likely to be earlier-born than non-heterosexual women. We found no significant differences between sexual orientation groups on measurements of 2D:4D ratio. This is one of the first studies to test and provide preliminary empirical support for an underlying neurodevelopmental basis to account for the lack of sexual attraction characteristic of asexuality.

  20. Hybridization and the Origin of Contagious Asexuality in Daphnia pulex

    Science.gov (United States)

    Xu, Sen; Spitze, Ken; Ackerman, Matthew S.; Ye, Zhiqiang; Bright, Lydia; Keith, Nathan; Jackson, Craig E.; Shaw, Joseph R.; Lynch, Michael

    2015-01-01

    Hybridization plays a potentially important role in the origin of obligate parthenogenesis (OP) in many organisms. However, it remains controversial whether hybridization directly triggers the transition from sexual reproduction to obligate asexuality or a hybrid genetic background enables asexual species to persist. Furthermore, we know little about the specific genetic elements from the divergent, yet still hybridizing lineages responsible for this transition and how these elements are further spread to create other OP lineages. In this study, we address these questions in Daphnia pulex, where cyclically parthenogenetic (CP) and OP lineages coexist. Ancestry estimates and whole-genome association mapping using 32 OP isolates suggest that a complex hybridization history between the parental species D. pulex and D. pulicaria is responsible for the introgression of a set of 647 D. pulicaria single nucleotide polymorphism alleles that show perfect association with OP. Crossing experiments using males of OP lineages and females of CP lineages strongly support a polygenic basis for OP. Single-sperm analyses show that although normal meiotic recombination occurs in the production of haploid sperm by males of OP lineages, a significant proportion of such sperm are polyploid, suggesting that the spread of asexual elements through these males (i.e., contagious asexuality) is much less efficient than previously envisioned. Although the current Daphnia genome annotation does not provide mechanistic insight into the nature of the asexuality-associated alleles, these alleles should be considered as candidates for future investigations on the genetic underpinnings of OP. PMID:26351296

  1. OncoSimulR: genetic simulation with arbitrary epistasis and mutator genes in asexual populations.

    Science.gov (United States)

    Diaz-Uriarte, Ramon

    2017-06-15

    OncoSimulR implements forward-time genetic simulations of biallelic loci in asexual populations with special focus on cancer progression. Fitness can be defined as an arbitrary function of genetic interactions between multiple genes or modules of genes, including epistasis, restrictions in the order of accumulation of mutations, and order effects. Mutation rates can differ among genes, and can be affected by (anti)mutator genes. Also available are sampling from simulations (including single-cell sampling), plotting the genealogical relationships of clones and generating and plotting fitness landscapes. Implemented in R and C ++, freely available from BioConductor for Linux, Mac and Windows under the GNU GPL license. Version 2.5.9 or higher available from: http://www.bioconductor.org/packages/devel/bioc/html/OncoSimulR.html . GitHub repository at: https://github.com/rdiaz02/OncoSimul. ramon.diaz@iib.uam.es. Supplementary data are available at Bioinformatics online.

  2. A validated measure of no sexual attraction: the Asexuality Identification Scale.

    Science.gov (United States)

    Yule, Morag A; Brotto, Lori A; Gorzalka, Boris B

    2015-03-01

    Human asexuality has been described as a lack of sexual attraction toward anyone or anything. One percent of the adult population is thought to be asexual, and research suggests that asexuality is best conceptualized as a sexual orientation. A serious limitation in past research on asexuality has been the complete lack of a validated tool to measure asexuality. Due to limitations in recruiting sufficiently powered local samples, most studies have relied on recruiting via online web-based asexual communities. This is problematic because it limits the sample to individuals who have been recruited through established asexuality networks/communities. The present study aimed to develop and validate a self-report questionnaire to assess asexuality. The questionnaire was intended to provide a valid measure independent of whether the individual self-identified as asexual and was developed in several stages, including: development and administration of open-ended questions (209 participants: 139 asexual and 70 sexual); administration and analysis of resulting 111 items (917 participants: 165 asexual and 752 sexual); administration and analysis of 37 retained items (1,242 participants: 316 asexual and 926 sexual); and validity analysis of the final items. The resulting Asexuality Identification Scale (AIS), a 12-item questionnaire, is a brief, valid, and reliable self-report instrument for assessing asexuality. It is psychometrically sound, easy to administer, and has demonstrated ability to discriminate between sexual and asexual individuals. It should prove useful to allow researchers to recruit more representative samples of the asexual population, permitting for an increased understanding of asexuality.

  3. What Asexuality Contributes to the Same-Sex Marriage Discussion.

    Science.gov (United States)

    Scherrer, Kristin S

    2010-01-01

    While same-sex marriage debates have captured public attention, it is but one component of a broader discussion regarding the role of marriage in a changing society. To inform this discussion, I draw on qualitative, Internet survey data from 102 self-identified asexual individuals. I find that asexual relationships are complicated and nuanced in ways that have implications for a GLBTQ political agenda, including same-sex marriage recognition. In addition, findings indicate that assumptions of sex and sexuality in relationships are problematic and that present language for describing relationships is limiting. Findings suggest a social justice agenda for marginalized sexualities should be broader in scope than same-sex marriage.

  4. Coexistence of sexual individuals and genetically isolated asexual counterparts in a thrips.

    OpenAIRE

    Kazuya Kobayashi; Jin Yoshimura; Eisuke Hasegawa

    2013-01-01

    Sex is a paradoxical phenomenon because it is less efficient compared with asexual reproduction. To resolve this paradox we need a direct comparison between sexual and asexual forms. In many organisms, however, sexual and asexual forms do not occur in the same habitat, or at the same time. In a few cases where sexual and asexual forms are found in a single population, some (though rare) genetic exchange is usually detected between the two forms. When genetic exchange occurs a direct compariso...

  5. Multigenerational demographic responses of sexual and asexual Artemia to chronic genotoxicity by a reference mutagen.

    Science.gov (United States)

    Sukumaran, Sandhya; Grant, Alastair

    2013-11-15

    Genotoxins are capable of multigenerational impacts on natural populations via DNA damage and mutations. Sexual reproduction is assumed to reduce the long term consequences of genotoxicity for individual fitness and should therefore reduce population level effects. However, rather few empirical studies have quantified the magnitude of this effect. We tried to analyse the multigenerational demographic responses of sexual Artemia franciscana and asexual Artemia parthenogenetica due to chronic genotoxicity by a reference mutagen, ethyl methane sulfonate (EMS). A prospective (elasticity analysis) and retrospective (differences and contributions) perturbation analysis was carried out to understand the interactions of life history traits with population growth rate λ by comparing elasticities, differences and contributions of vital rates to λ. None of the previous studies have compared the effects of chronic genotoxicity using prospective and retrospective perturbation analyses in a sexual and asexual species over generations. The behaviour of a population with lower growth rate in the presence of genotoxicants in the field was studied by simulating reduced fertilities in the LTRE design. The results of prospective and retrospective perturbation analyses of effects on λ showed that population growth rate was proportionally more sensitive to juvenile survival whereas the effect of EMS on juvenile fertility contributed more to the variations in population growth rate in both the species and this effect was due to the high growth rate of Artemia. Simulations of lower population growth rate in the model showed that adult fertility and survival are also of importance. Sexual reproduction substantially mitigated the long term consequences of genetic damage, although these would be greater if population growth rate were lower. So multigenerational population level consequences of genotoxicity were much greater in an asexual species. So asexual species, and those with a

  6. What can asexual lineage age tell us about the maintenance of sex?

    Science.gov (United States)

    Neiman, Maurine; Meirmans, Stephanie; Meirmans, Patrick G

    2009-06-01

    Sexual reproduction is both extremely costly and extremely common relative to asexuality, indicating that it must confer profound benefits. This in turn points to major disadvantages of asexual reproduction, which is usually given as an explanation for why almost all asexual lineages are apparently quite short-lived. However, a growing body of evidence suggests that some asexual lineages are actually quite old. Insight into why sex is so common may come from understanding why asexual lineages persist in some places or taxa but not others. Here, we review the distribution of asexual lineage ages estimated from a diverse array of taxa, and we discuss our results in light of the main mutational and environmental hypotheses for sex. Along with strengthening the case for wide variation in asexual lineage age and the existence of many old asexual taxa, we also found that the distribution of asexual lineage age estimates follows a surprisingly regular distribution, to the extent that asexual taxa viewed as "scandalously" ancient merely fall on the high end of this distribution. We interpret this result to mean that similar mechanisms may determine asexual lineage age across eukaryotic taxa. We also derive some qualitative predictions for asexual lineage age under different theories for sex and discuss empirical evidence for these predictions. Ultimately, we were limited in the extent to which we could use these data to make inferences about the maintenance of sex by the absence of both clear theoretical expectations and estimates of key parameters.

  7. The effect of population bottlenecks on mutation rate evolution in asexual populations.

    Science.gov (United States)

    Raynes, Y; Halstead, A L; Sniegowski, P D

    2014-01-01

    In the absence of recombination, a mutator allele can spread through a population by hitchhiking with beneficial mutations that appear in its genetic background. Theoretical studies over the past decade have shown that the survival and fixation probability of beneficial mutations can be severely reduced by population size bottlenecks. Here, we use computational modelling and evolution experiments with the yeast S. cerevisiae to examine whether population bottlenecks can affect mutator dynamics in adapting asexual populations. In simulation, we show that population bottlenecks can inhibit mutator hitchhiking with beneficial mutations and are most effective at lower beneficial mutation supply rates. We then subjected experimental populations of yeast propagated at the same effective population size to three different bottleneck regimes and observed that the speed of mutator hitchhiking was significantly slower at smaller bottlenecks, consistent with our theoretical expectations. Our results, thus, suggest that bottlenecks can be an important factor in mutation rate evolution and can in certain circumstances act to stabilize or, at least, delay the progressive elevation of mutation rates in asexual populations. Additionally, our findings provide the first experimental support for the theoretically postulated effect of population bottlenecks on beneficial mutations and demonstrate the usefulness of studying mutator frequency dynamics for understanding the underlying dynamics of fitness-affecting mutations.

  8. Hassan Aga and his Government in Algiers. The Consolidation of a Mediterranean Myth

    Directory of Open Access Journals (Sweden)

    Fernando FERNÁNDEZ LANZA

    2014-12-01

    Full Text Available This work tries to describe graphically the consolidation of a social myth in the unsettled Mediterranean of the 16th century, through a personage: the Spanish convert to Islam Hassan Aga (Azan Aga, the Sardinian renegade who succeeded Hayreddin Barbarrosa at the helms of Algiers from 1533 till his death ten years later. This was a period of intense activity, with the climax that came with the expedition of Charles to Algiers in 1541, whose spectacular defeat can be considered as the principal nucleus of the myth of this popular personage who as a Sardinian slave came to defeat the Emperor. A myth of social ascension with maquiavelical profiles of a new prince of the frontiers.

  9. Deleterious Mutation Accumulation in Asexual Timema Stick Insects

    NARCIS (Netherlands)

    Henry, Lee; Schwander, Tanja; Crespi, Bernard J.

    2012-01-01

    Sexual reproduction is extremely widespread in spite of its presumed costs relative to asexual reproduction, indicating that it must provide significant advantages. One postulated benefit of sex and recombination is that they facilitate the purging of mildly deleterious mutations, which would accumu

  10. Does an asexual endophyte symbiont alter life stage and long-term survival in a perennial host grass?

    Science.gov (United States)

    Faeth, Stanley H; Hamilton, Cyd E

    2006-11-01

    Asexual, seedborne endophytic fungi in perennial grasses are often viewed as strong mutualists because fitness of the symbiont and host grass are closely coupled. However, at least for some native grasses, the asexual endophyte, Neotyphodium, acts parasitically, yet remains at high frequencies in natural populations. Most previous studies of Neotyphodium effects on host survival have been short term relative to the long life span of the perennial grass host. We therefore tested the hypothesis that Neotyphodium alters the survival in various life stages and long-term survival of adult native Arizona fescue (Festuca arizonica). To test the former, we planted 40 infected (E+) and 40 uninfected (E-, endophyte removed) seeds from four different maternal plants in the field under ambient conditions. We followed survival of seeds, seedlings, and adult plants over a 5-year period. To test the latter, we determined the infection of 1633 adult plants and followed their survival over the next 5-7 years. E+ seeds did not differ from uninfected seeds in terms of overall survival from seed germination to seedling to adult. However, the shape of the survival curve differed, with E+ plants showing higher mortality in early life stages. E+ adult plants did not differ from E- plants in long-term survival. Survival was generally very high during the study, which included a severe and prolonged drought. Infection by asexual Neotyphodium does not increase survival in early life stages or that of adult plants. Because asexual, vertically transmitted symbionts are predicted by evolutionary theory to be strong mutualists, the persistence of high infection frequencies in natural populations without long-term benefits to the host remains enigmatic. One possible explanation is that the long life span of the perennial host and low seedling recruitment may obscure either the costs or benefits of endophyte infection.

  11. Cryptic species in putative ancient asexual darwinulids (Crustacea, Ostracoda.

    Directory of Open Access Journals (Sweden)

    Isa Schön

    Full Text Available BACKGROUND: Fully asexually reproducing taxa lack outcrossing. Hence, the classic Biological Species Concept cannot be applied. METHODOLOGY/PRINCIPAL FINDINGS: We used DNA sequences from the mitochondrial COI gene and the nuclear ITS2 region to check species boundaries according to the evolutionary genetic (EG species concept in five morphospecies in the putative ancient asexual ostracod genera, Penthesilenula and Darwinula, from different continents. We applied two methods for detecting cryptic species, namely the K/θ method and the General Mixed Yule Coalescent model (GMYC. We could confirm the existence of species in all five darwinulid morphospecies and additional cryptic diversity in three morphospecies, namely in Penthesilenula brasiliensis, Darwinula stevensoni and in P. aotearoa. The number of cryptic species within one morphospecies varied between seven (P. brasiliensis, five to six (D. stevensoni and two (P. aotearoa, respectively, depending on the method used. Cryptic species mainly followed continental distributions. We also found evidence for coexistence at the local scale for Brazilian cryptic species of P. brasiliensis and P. aotearoa. Our ITS2 data confirmed that species exist in darwinulids but detected far less EG species, namely two to three cryptic species in P. brasiliensis and no cryptic species at all in the other darwinulid morphospecies. CONCLUSIONS/SIGNIFICANCE: Our results clearly demonstrate that both species and cryptic diversity can be recognized in putative ancient asexual ostracods using the EG species concept, and that COI data are more suitable than ITS2 for this purpose. The discovery of up to eight cryptic species within a single morphospecies will significantly increase estimates of biodiversity in this asexual ostracod group. Which factors, other than long-term geographic isolation, are important for speciation processes in these ancient asexuals remains to be investigated.

  12. Hybridization and the Origin of Contagious Asexuality in Daphnia pulex.

    Science.gov (United States)

    Xu, Sen; Spitze, Ken; Ackerman, Matthew S; Ye, Zhiqiang; Bright, Lydia; Keith, Nathan; Jackson, Craig E; Shaw, Joseph R; Lynch, Michael

    2015-12-01

    Hybridization plays a potentially important role in the origin of obligate parthenogenesis (OP) in many organisms. However, it remains controversial whether hybridization directly triggers the transition from sexual reproduction to obligate asexuality or a hybrid genetic background enables asexual species to persist. Furthermore, we know little about the specific genetic elements from the divergent, yet still hybridizing lineages responsible for this transition and how these elements are further spread to create other OP lineages. In this study, we address these questions in Daphnia pulex, where cyclically parthenogenetic (CP) and OP lineages coexist. Ancestry estimates and whole-genome association mapping using 32 OP isolates suggest that a complex hybridization history between the parental species D. pulex and D. pulicaria is responsible for the introgression of a set of 647 D. pulicaria single nucleotide polymorphism alleles that show perfect association with OP. Crossing experiments using males of OP lineages and females of CP lineages strongly support a polygenic basis for OP. Single-sperm analyses show that although normal meiotic recombination occurs in the production of haploid sperm by males of OP lineages, a significant proportion of such sperm are polyploid, suggesting that the spread of asexual elements through these males (i.e., contagious asexuality) is much less efficient than previously envisioned. Although the current Daphnia genome annotation does not provide mechanistic insight into the nature of the asexuality-associated alleles, these alleles should be considered as candidates for future investigations on the genetic underpinnings of OP. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Noored soovivad töötada erasektoris, vanemad aga avalikus sektoris / Ülle Pärnoja

    Index Scriptorium Estoniae

    Pärnoja, Ülle

    2008-01-01

    TNS Emori tööandjate maine uuring näitab, et 37% palgatöötajatena leiba teenivatest noorematest inimestest eelistab töötada erasektoris, ligi 40% keskealistest ja vanematest inimestest aga avalikus sektoris

  14. Asexuality: Sexual Orientation, Paraphilia, Sexual Dysfunction, or None of the Above?

    Science.gov (United States)

    Brotto, Lori A; Yule, Morag

    2017-04-01

    Although lack of sexual attraction was first quantified by Kinsey, large-scale and systematic research on the prevalence and correlates of asexuality has only emerged over the past decade. Several theories have been posited to account for the nature of asexuality. The goal of this review was to consider the evidence for whether asexuality is best classified as a psychiatric syndrome (or a symptom of one), a sexual dysfunction, or a paraphilia. Based on the available science, we believe there is not sufficient evidence to support the categorization of asexuality as a psychiatric condition (or symptom of one) or as a disorder of sexual desire. There is some evidence that a subset of self-identified asexuals have a paraphilia. We also considered evidence supporting the classification of asexuality as a unique sexual orientation. We conclude that asexuality is a heterogeneous entity that likely meets conditions for a sexual orientation, and that researchers should further explore evidence for such a categorization.

  15. Ex-vivo assessment and non-invasive in vivo imaging of internal hemorrhages in Aga2/+ mutant mice

    Energy Technology Data Exchange (ETDEWEB)

    Ermolayev, Vladimir [Institute for Biological and Medical Imaging, Helmholtz Zentrum München, Building 56, Ingolstädter Landstraße 1, D-85764 Neuherberg (Germany); Cohrs, Christian M. [Institute for Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, D-85764 Neuherberg (Germany); Mohajerani, Pouyan; Ale, Angelique [Institute for Biological and Medical Imaging, Helmholtz Zentrum München, Building 56, Ingolstädter Landstraße 1, D-85764 Neuherberg (Germany); Hrabé de Angelis, Martin [Institute for Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, D-85764 Neuherberg (Germany); Ntziachristos, Vasilis, E-mail: v.ntziachristos@tum.de [Institute for Biological and Medical Imaging, Helmholtz Zentrum München, Building 56, Ingolstädter Landstraße 1, D-85764 Neuherberg (Germany)

    2013-03-08

    Highlights: ► Aga2/+ mice, model for Osteogenesis imperfecta, have type I collagen mutation. ► Aga2/+ mice display both moderate and severe phenotypes lethal 6–11th postnatal. ► Internal hemorrhages studied in Aga2/+ vs. control mice at 6 and 9 days postnatal. ► Anatomical and functional findings in-vivo contrasted to the ex-vivo appearance. -- Abstract: Mutations in type I collagen genes (COL1A1/2) typically lead to Osteogenesis imperfecta, the most common heritable cause of skeletal fractures and bone deformation in humans. Heterozygous Col1a1{sup Aga2/+}, animals with a dominant mutation in the terminal C-propeptide domain of type I collagen develop typical skeletal hallmarks and internal hemorrhages starting from 6 day after birth. The disease progression for Aga2/+ mice, however, is not uniform differing between severe phenotype lethal at the 6–11th day of life, and moderate-to-severe one with survival to adulthood. Herein we investigated whether a new modality that combines X-ray computer tomography with fluorescence tomography in one hybrid system can be employed to study internal bleedings in relation to bone fractures and obtain insights into disease progression. The disease phenotype was characterized on Aga2/+ vs. wild type mice between 6 and 9 days postnatal. Anatomical and functional findings obtained in-vivo were contrasted to the ex-vivo appearance of the same tissues under cryo-slicing.

  16. Do asexual polyploid lineages lead short evolutionary lives? A case study from the fern genus Astrolepis.

    Science.gov (United States)

    Beck, James B; Windham, Michael D; Pryer, Kathleen M

    2011-11-01

    A life-history transition to asexuality is typically viewed as leading to a heightened extinction risk, and a number of studies have evaluated this claim by examining the relative ages of asexual versus closely related sexual lineages. Surprisingly, a rigorous assessment of the age of an asexual plant lineage has never been published, although asexuality is extraordinarily common among plants. Here, we estimate the ages of sexual diploids and asexual polyploids in the fern genus Astrolepis using a well-supported plastid phylogeny and a relaxed-clock dating approach. The 50 asexual polyploid samples we included were conservatively estimated to comprise 19 distinct lineages, including a variety of auto- and allopolyploid genomic combinations. All were either the same age or younger than the crown group comprising their maternal sexual-diploid parents based simply on their phylogenetic position. Node ages estimated with the relaxed-clock approach indicated that the average maximum age of asexual lineages was 0.4 My, and individual lineages were on average 7 to 47 times younger than the crown- and total-ages of their sexual parents. Although the confounding association between asexuality and polyploidy precludes definite conclusions regarding the effect of asexuality, our results suggest that asexuality limits evolutionary potential in Astrolepis.

  17. Physiological and subjective sexual arousal in self-identified asexual women.

    Science.gov (United States)

    Brotto, Lori A; Yule, Morag A

    2011-08-01

    Asexuality can be defined as a lifelong lack of sexual attraction. Empirical research on asexuality reveals significantly lower self-reported sexual desire and arousal and lower rates of sexual activity; however, the speculation that there may also be an impaired psychophysiological sexual arousal response has never been tested. The aim of this study was to compare genital (vaginal pulse amplitude; VPA) and subjective sexual arousal in asexual and non-asexual women. Thirty-eight women between the ages of 19 and 55 years (10 heterosexual, 10 bisexual, 11 homosexual, and 7 asexual) viewed neutral and erotic audiovisual stimuli while VPA and self-reported sexual arousal and affect were measured. There were no significant group differences in the increased VPA and self-reported sexual arousal response to the erotic film between the groups. Asexuals showed significantly less positive affect, sensuality-sexual attraction, and self-reported autonomic arousal to the erotic film compared to the other groups; however, there were no group differences in negative affect or anxiety. Genital-subjective sexual arousal concordance was significantly positive for the asexual women and non-significant for the other three groups, suggesting higher levels of interoceptive awareness among asexuals. Taken together, the findings suggest normal subjective and physiological sexual arousal capacity in asexual women and challenge the view that asexuality should be characterized as a sexual dysfunction.

  18. Insertion Polymorphisms of Mobile Genetic Elements in Sexual and Asexual Populations of Daphnia pulex

    Science.gov (United States)

    Ye, Zhiqiang; Lynch, Michael

    2017-01-01

    Transposable elements (TEs) constitute a substantial portion of many eukaryotic genomes, and can in principle contribute to evolutionary innovation as well as genomic deterioration. Daphnia pulex serves as a useful model for studying TE dynamics as a potential cause and/or consequence of asexuality. We analyzed insertion polymorphisms of TEs in 20 sexual and 20 asexual isolates of D. pulex across North American from their available whole-genome sequencing data. Our results show that the total fraction of the derived sequences of TEs is not substantially different between asexual and sexual D. pulex isolates. However, in general, sexual clones contain fewer fixed TE insertions but more total insertion polymorphisms than asexual clones, supporting the hypothesis that sexual reproduction facilitates the spread and elimination of TEs. We identified nine asexual-specific fixed TE insertions, eight long terminal repeat retrotransposons, and one DNA transposon. By comparison, no sexual-specific fixed TE insertions were observed in our analysis. Furthermore, except one TE insertion located on a contig from chromosome 7, the other eight asexual-specific insertion sites are located on contigs from chromosome 9 that is known to be associated with obligate asexuality in D. pulex. We found that all nine asexual-specific fixed TE insertions can also be detected in some Daphnia pulicaria isolates, indicating that a substantial number of TE insertions in asexual D. pulex have been directly inherited from D. pulicaria during the origin of obligate asexuals. PMID:28057730

  19. Insertion polymorphisms of mobile genetic elements in sexual and asexual populations of Daphnia pulex.

    Science.gov (United States)

    Jiang, Xiaoqian; Tang, Haixu; Ye, Zhiqiang; Lynch, Michael

    2017-01-04

    Transposable elements (TEs) constitute a substantial portion of many eukaryotic genomes, and can in principle contribute to evolutionary innovation as well as genomic deterioration. Daphnia pulex serves as a useful model for studying TE dynamics as a potential cause and/or consequence of asexuality. We analyzed insertion polymorphisms of TEs in 20 sexual and 20 asexual isolates of D. pulex across North American from their available whole-genome sequencing data. Our results show that the total fraction of the derived sequences of TEs is not substantially different between asexual and sexual D. pulex isolates. However, in general, sexual clones contain fewer fixed TE insertions but more total insertion polymorphisms than asexual clones, supporting the hypothesis that sexual reproduction facilitates the spread and elimination of TEs. We identified 9 asexual-specific fixed TE insertions, 8 LTR retrotransposons and 1 DNA transposon. By comparison, no sexual-specific fixed TE insertions were observed in our analysis. Furthermore, except 1 TE insertion located on a contig from chromosome 7, the other 8 asexual-specific insertion sites are located on contigs from chromosome 9 that is known to be associated with obligate asexuality in D. pulex. We found that all 9 asexual-specific fixed TE insertions can also be detected in some D. pulicaria isolates, indicating that a substantial number of TE insertions in asexual D. pulex have been directly inherited from D. pulicaria during the origin of obligate asexuals.

  20. Sexual Fantasy and Masturbation Among Asexual Individuals: An In-Depth Exploration.

    Science.gov (United States)

    Yule, Morag A; Brotto, Lori A; Gorzalka, Boris B

    2017-01-01

    Human asexuality is generally defined as a lack of sexual attraction. We used online questionnaires to investigate reasons for masturbation, and explored and compared the contents of sexual fantasies of asexual individuals (identified using the Asexual Identification Scale) with those of sexual individuals. A total of 351 asexual participants (292 women, 59 men) and 388 sexual participants (221 women, 167 men) participated. Asexual women were significantly less likely to masturbate than sexual women, sexual men, and asexual men. Asexual women were less likely to report masturbating for sexual pleasure or fun than their sexual counterparts, and asexual men were less likely to report masturbating for sexual pleasure than sexual men. Both asexual women and men were significantly more likely than sexual women and men to report that they had never had a sexual fantasy. Of those who have had a sexual fantasy, asexual women and men were significantly more likely to endorse the response "my fantasies do not involve other people" compared to sexual participants, and consistently scored each sexual fantasy on a questionnaire as being less sexually exciting than did sexual participants. When using an open-ended format, asexual participants were more likely to report having fantasies about sexual activities that did not involve themselves, and were less likely to fantasize about topics such as group sex, public sex, and having an affair. Interestingly, there was a large amount of overlap between sexual fantasies of asexual and sexual participants. Notably, both asexual and sexual participants (both men and women) were equally likely to fantasize about topics such as fetishes and BDSM.

  1. Gonad establishment during asexual reproduction in the annelid Pristina leidyi.

    Science.gov (United States)

    Özpolat, B Duygu; Bely, Alexandra E

    2015-09-01

    Animals that can reproduce by both asexual agametic reproduction and sexual reproduction must transmit or re-establish their germ line post-embryonically. Although such a dual reproductive mode has evolved repeatedly among animals, how asexually produced individuals establish their germ line remains poorly understood in most groups. We investigated germ line development in the annelid Pristina leidyi, a species that typically reproduces asexually by paratomic fission, intercalating a new tail and head in the middle of the body followed by splitting. We found that in fissioning individuals, gonads occur in anterior segments in the anterior-most individual as well as in new heads forming within fission zones. Homologs of the germ line/multipotency genes piwi, vasa, and nanos are expressed in the gonads, as well as in proliferative tissues including the posterior growth zone, fission zone, and regeneration blastema. In fissioning animals, certain cells on the ventral nerve cord express a homolog of piwi, are abundant near fission zones, and sometimes make contact with gonads. Such cells are typically undetectable near the blastema and posterior growth zone. Time-lapse imaging provides direct evidence that cells on the ventral nerve cord migrate preferentially towards fission zones. Our findings indicate that gonads form routinely in fissioning individuals, that a population of piwi-positive cells on the ventral nerve cord is associated with fission and gonads, and that cells resembling these piwi-positive cells migrate along the ventral nerve cord. We suggest that the piwi-positive ventral cells are germ cells that transmit the germ line across asexually produced individuals via migration along the ventral nerve cord. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. The Genetic Control of Apomixis: Asexual Seed Formation

    OpenAIRE

    Hand, Melanie L; Koltunow, Anna M. G.

    2014-01-01

    Apomixis (asexual seed formation) is the result of a plant gaining the ability to bypass the most fundamental aspects of sexual reproduction: meiosis and fertilization. Without the need for male fertilization, the resulting seed germinates a plant that develops as a maternal clone. This dramatic shift in reproductive process has been documented in many flowering plant species, although no major seed crops have been shown to be capable of apomixis. The ability to generate maternal clones and t...

  3. "Parim" on subjektiivne, aga kõhutundest ka ei piisa / Inga Kuusik

    Index Scriptorium Estoniae

    Kuusik, Inga, 1961-

    2007-01-01

    Ilmunud ka: Finansovõi Menedzhment : infovõpusk nr. 13 apr. lk. 6-7. Saku Õlletehase uus finantsjuht oma tööst tubakatootja Imperial Tobacco Grupi Kesk-Aasia regiooni finantsdirektorina Kõrgõzstanis, Saku Õlletehase kapitali struktuurist, finantsdirektori rollist ettevõttes ja tööjõu värbamisest Saku Õlletehases. Lisad: Saku Õlletehas 2006: mõõdukas käibe-, aga suur kasumikasv; Tabel: Saku Õlletehase dividendimaksed 1997-2007

  4. "Parim" on subjektiivne, aga kõhutundest ka ei piisa / Inga Kuusik

    Index Scriptorium Estoniae

    Kuusik, Inga, 1961-

    2007-01-01

    Ilmunud ka: Finansovõi Menedzhment : infovõpusk nr. 13 apr. lk. 6-7. Saku Õlletehase uus finantsjuht oma tööst tubakatootja Imperial Tobacco Grupi Kesk-Aasia regiooni finantsdirektorina Kõrgõzstanis, Saku Õlletehase kapitali struktuurist, finantsdirektori rollist ettevõttes ja tööjõu värbamisest Saku Õlletehases. Lisad: Saku Õlletehas 2006: mõõdukas käibe-, aga suur kasumikasv; Tabel: Saku Õlletehase dividendimaksed 1997-2007

  5. Morphogenesis during asexual reproduction in Pygospio elegans Claparede (Annelida, Polychaeta).

    Science.gov (United States)

    Gibson, G D; Harvey, J M

    2000-08-01

    The spionid Pygospio elegans reproduces both asexually and sexually. Using scanning electron and bright field microscopy, we examined morphogenesis following asexual reproduction to determine how "lost" body regions were regenerated after a worm spontaneously divided. Asexual reproduction occurred through transverse fission and divided the parent worm into 2 to 6 fragments (architomy). All fragments retained their original anterior-posterior polarity. Regeneration in all fragments followed a specific series of events: wound healing (day 1); extension of the blastema to generate lost body regions-specifically, the head and thorax for posterior fragments and the tail and pygidium for anterior fragments (days 2-3); segmentation (days 3-6); and differentiation of segment- or region-specific structures (days 4-8). This pattern occurred regardless of where the original division took place. Subsequent growth occurred through addition of terminal setigers anterior to the pygidium followed by differentiation of tail setigers into abdominal setigers, leaving the tail region about 6 to 10 setigers in size. Division rates were compared in worms from three populations in Nova Scotia, Canada. Worms from two populations (Conrad's Beach, Starr's Point) divided more frequently (about 1.2 and 1.3 weeks between divisions, respectively) than worms from Bon Portage Island (3.5 weeks between divisions). Fragments containing the original head (original mouth intact, generally much larger fragment) had a higher survivorship than fragments containing the original tail.

  6. Genetic variation in organisms with sexual and asexual reproduction.

    Science.gov (United States)

    Bengtsson, B O

    2003-03-01

    The genetic variation in a partially asexual organism is investigated by two models suited for different time scales. Only selectively neutral variation is considered. Model 1 shows, by the use of a coalescence argument, that three sexually derived individuals per generation are sufficient to give a population the same pattern of allelic variation as found in fully sexually reproducing organisms. With less than one sexual event every third generation, the characteristic pattern expected for asexual organisms appear, with strong allelic divergence between the gene copies in individuals. At intermediary levels of sexuality, a complex situation reigns. The pair-wise allelic divergence under partial sexuality exceeds, however, always the corresponding value under full sexuality. These results apply to large populations with stable reproductive systems. In a more general framework, Model 2 shows that a small number of sexual individuals per generation is sufficient to make an apparently asexual population highly genotypically variable. The time scale in terms of generations needed to produce this effect is given by the population size and the inverse of the rate of sexuality.

  7. Coexistence of sexual individuals and genetically isolated asexual counterparts in a thrips.

    Science.gov (United States)

    Kobayashi, Kazuya; Yoshimura, Jin; Hasegawa, Eisuke

    2013-11-21

    Sex is a paradoxical phenomenon because it is less efficient compared with asexual reproduction. To resolve this paradox we need a direct comparison between sexual and asexual forms. In many organisms, however, sexual and asexual forms do not occur in the same habitat, or at the same time. In a few cases where sexual and asexual forms are found in a single population, some (though rare) genetic exchange is usually detected between the two forms. When genetic exchange occurs a direct comparison is impossible. Here we investigate a thrips exhibiting both sexual and asexual forms (lineages) that are morphologically indistinguishable. We examine if the two forms are genetically isolated. Phylogeny based on nuclear genes confirms that the sexual and asexual lineages are genetically differentiated. Thus we demonstrate that the current system has certain advantages over existing and previously used model systems in the evolution of sexual reproduction.

  8. Morphological characterization of the asexual reproduction in the acorn worm Balanoglossus simodensis.

    Science.gov (United States)

    Miyamoto, Norio; Saito, Yasunori

    2010-09-01

    The acorn worm Balanoglossus simodensis reproduces asexually by fragmentation and subsequent regeneration from the body fragments. We examined the morphogenesis of its asexual reproduction. At first, we collected asexually reproducing specimens and observed their morphogenesis. Then, we succeeded in inducing the asexual reproduction artificially by cutting the worm at the end of the genital region. The process of morphogenesis is completely the same between naturally collected and artificially induced specimens. The stages during morphogenesis were established on the basis of the external features of the asexually reproducing fragments. The internal features of the fragments were also examined at each stage. In a separate phase of the study, the capacity for regeneration of some body parts was also examined by dividing intact worms into about 10 fragments. Although the capacity for regeneration varied among the different body parts, some fragments regenerated into complete individuals in 1 month. The process of regeneration was the same as that in the asexually produced fragments.

  9. Single-locus recessive inheritance of asexual reproduction in a parasitoid wasp.

    Science.gov (United States)

    Sandrock, Christoph; Vorburger, Christoph

    2011-03-08

    The evolutionary maintenance of sex is one of the big unresolved puzzles in biology. All else being equal, all-female asexual populations should enjoy a two-fold reproductive advantage over sexual relatives consisting of male and female individuals. However, the "all else being equal" assumption rarely holds in real organisms because asexuality tends to be confounded with altered genomic constitutions such as hybridization and polyploidization or to be associated with parthenogenesis-inducing microbes. This limits the ability to draw general conclusions from any particular system. Here we describe a new system that permits unbiased comparisons of sexual and asexual reproduction: the parasitic wasp Lysiphlebus fabarum. Crossing experiments demonstrated that asexual reproduction has a simple genetic basis in this species and is consistently inherited as a single-locus recessive trait. We further show that the asexuality-inducing allele exhibits complete linkage to a specific allele at a microsatellite marker: all asexual lines in the field were homozygous for this allele, and the allele cosegregated perfectly with asexual reproduction in our experimental crossings. This novel system of contagious asexuality allows the production of closely related individuals with different reproductive modes, as well as the monitoring of the asexuality-inducing allele in natural and experimental populations.

  10. Existence of two sexual races in the planarian species switching between asexual and sexual reproduction.

    Science.gov (United States)

    Kobayashi, Kazuya; Maezawa, Takanobu; Nakagawa, Haruka; Hoshi, Motonori

    2012-04-01

    In certain planarian species that are able to switch between asexual and sexual reproduction, determining whether a sexual has the ability to switch to the asexual state is problematic, which renders the definition of sexuals controversial. We experimentally show the existence of two sexual races, acquired and innate, in the planarian Dugesia ryukyuensis. Acquired sexuals used in this study were experimentally switched from asexuals. Inbreeding of acquired sexuals produced both innate sexuals and asexuals, but inbreeding of innate sexuals produced innate sexuals only and no asexuals. Acquired sexuals, but not innate sexuals, were forced to become asexuals by ablation and regeneration (asexual induction). This suggests that acquired sexuals somehow retain asexual potential, while innate sexuals do not. We also found that acquired sexuals have the potential to develop hyperplastic and supernumerary ovaries, while innate sexuals do not. In this regard, acquired sexuals were more prolific than innate sexuals. The differences between acquired and innate sexuals will provide a structure for examining the mechanism underlying asexual and sexual reproduction in planarians.

  11. AGA: Interactive pipeline for reproducible gene expression and DNA methylation data analyses [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Michael Considine

    2015-10-01

    Full Text Available Automated Genomics Analysis (AGA is an interactive program to analyze high-throughput genomic data sets on a variety of platforms. An easy to use, point and click, guided pipeline is implemented to combine, define, and compare datasets, and customize their outputs. In contrast to other automated programs, AGA enables flexible selection of sample groups for comparison from complex sample annotations. Batch correction techniques are also included to further enable the combination of datasets from diverse studies in this comparison. AGA also allows users to save plots, tables and data, and log files containing key portions of the R script run for reproducible analyses. The link between the interface and R supports collaborative research, enabling advanced R users to extend preliminary analyses generated from bioinformatics novices.

  12. Ribosome can resume the translation in both +1 or -1 frames after encountering an AGA cluster in Escherichia coli.

    Science.gov (United States)

    Lainé, Sébastien; Thouard, Anne; Komar, Anton A; Rossignol, Jean-Michel

    2008-04-15

    In Escherichia coli the rare codons AGG, AGA and CGA are reported to have a detrimental effect on protein synthesis, especially during the expression of heterologous proteins. In the present work, we have studied the impact of successive clusters of these rare codons on the accuracy of mRNA translation in E. coli. For this purpose, we have analyzed the expression of an mRNA which contains in its 3' region a triplet and a tandem of AGA codons. This mRNA is derived from the human hepatitis B virus (HBV) preC gene. Both in eukaryotic cells and in eukaryotic cell-free translation system, this mRNA, directs the synthesis of a single 25 kDa protein. However, in a conventional E. coli strain BL 21 (DE3), transformed with a plasmid expressing this protein the synthesis of four polypeptides ranging from 30 to 21.5 kDa can be observed. Using different approaches, notably expression of i) precore mutated proteins or ii) chimeric proteins containing HA- and Myc-tags downstream of the AGA clusters (respectively in the -1 or +1 frame), we have found that when the ribosome encounters the AGA clusters, it can then resume the translation in both +1 and -1 frames. This result is in agreement with the model proposed recently by Baranov et al. (Baranov, P.V., Gesteland, R.F., Atkins, J.F., 2004. P-site tRNA is a crucial initiator of ribosomal frameshifting. RNA 10, 221-230), thus confirming that AGA/AGG codons can serve as sites for -1 frameshifting events. Only +1 frameshifting was suggested previously to occur at the AGA/AGG clusters.

  13. Evaluation of elevated ploidy and asexual reproduction as alternative explanations for geographic parthenogenesis in Eucypris virens ostracods.

    Science.gov (United States)

    Adolfsson, Sofia; Michalakis, Yannis; Paczesniak, Dorota; Bode, Saskia N S; Butlin, Roger K; Lamatsch, Dunja K; Martins, Maria J F; Schmit, Olivier; Vandekerkhove, Jochen; Jokela, Jukka

    2010-04-01

    Transitions from sexual to asexual reproduction are often coupled with elevations in ploidy. As a consequence, the importance of ploidy per se for the maintenance and spread of asexual populations is unclear. To examine the effects of ploidy and asexual reproduction as independent determinants of the success of asexual lineages, we sampled diploid sexual, diploid asexual, and triploid asexual Eucypris virens ostracods across a European wide range. Applying nuclear and mitochondrial markers, we found that E. virens consists of genetically highly differentiated diploid sexual populations, to the extent that these sexual clades could be considered as cryptic species. All sexual populations were found in southern Europe and North Africa and we found that both diploid asexual and triploid asexual lineages have originated multiple times from several sexual lineages. Therefore, the asexual lineages show a wide variety of genetic backgrounds and very strong population genetic structure across the wide geographic range. Finally, we found that triploid, but not diploid, asexual clones dominate habitats in northern Europe. The limited distribution of diploid asexual lineages, despite their shared ancestry with triploid asexual lineages, strongly suggests that the wider geographic distribution of triploids is due to elevated ploidy rather than to asexuality.

  14. Morphology offers no clues to asexual vs. sexual origin of small Acropora cervicornis (Scleractinia: Acroporidae colonies

    Directory of Open Access Journals (Sweden)

    D. E Williams

    2006-12-01

    Full Text Available Sexual recruitment of the staghorn coral, Acropora cervicornis, is accepted to be very rare. Instead, these branching corals proliferate through fragmentation leading to dense mono-specific and possibly monoclonal stands. For acroporid corals, which have suffered drastic population declines, dominance of asexual reproduction results in low levels of genotypic diversity and limited ability to re-colonize extirpated areas. Small colonies with a single encrusting, symmetrical base, and few incipient branches are frequently presumed to be the result of a settled planula (i.e. sexual reproduction. Here, we show that colonies fitting this description (i.e., presumed sexual recruits can result from asexual fragmentation. Acropora cervicornis colonies (~20 cm diameter were tagged and observed over eighteen months. In several cases, colony offshoots fused with the adjacent substrate forming secondary disc-like attachment points. Following natural fragmentation, these discs of tissue became separated from the original colony, and were observed to heal and give rise to smaller colonies with striking similarity to the expected morphology of a sexual recruit. Thus, presuming a colony is a sexual recruit based on appearance is unreliable and may lead to inflated expectations of genetic diversity among populations. The accurate assessment of recruitment and genetic diversity is crucial to predicting the recovery potential of these imperiled and ecologically irreplaceable reef corals. Rev. Biol. Trop. 54 (Suppl. 3: 145-151. Epub 2007 Jan. 15.Se ha aceptado que el reclutamiento sexual del coral asta de venado, Acropora cervicornis, es muy raro. Por el contrario, estos corales ramificados proliferan a través de fragmentación, generando densas bases monoespecíficas e incluso monoclonales. Para corales acropóridos, los cuales han sufrido disminuciones de población drásticas, la dominancia de reproducción asexual resulta en bajos niveles de diversidad genot

  15. An extracellular inducer of asexual plasmodium formation in Physarum polycephalum.

    Science.gov (United States)

    Youngman, P J; Adler, P N; Shinnick, T M; Holt, C E

    1977-01-01

    Asexual conversion of amoebae to plasmodia was studied in the Colonia isolate of the myxomycete, Physarum polycephalum. When a culture of Colonia amoebae is grown on a bacterial lawn, a period of amoebic growth precedes the appearance of cells committed to the plasmodial state. The onset of plasmodium production appears to be related to amoebic nutrition since cultures supplied with fewer bacteria display earlier differentiation. For a period of time after differentiation is initiated, conversion of amoebae to plasmodia is rapid and proceeds as an exponential function of time. A filter-transmissible substance, apparently released by differentiating cells, is implicated in the control of this rapid conversion. Images PMID:265558

  16. Simulated emergence of cyclic sexual-asexual reproduction

    Science.gov (United States)

    Sá Martins, J. S.; Racco, A.

    2001-08-01

    Motivated by the cyclic pattern of reproductive regimes observed in some species of green flies (“ aphids”), we simulate the evolution of a population enduring harsh seasonal conditions for survival. The reproductive regime of each female is also seasonal in principle and genetically acquired, and can mutate for each newborn with some small probability. The results show a sharp transition at a critical value of the survival probability in the winter, between a reproductive regime in the fall that is predominantly sexual, for low values of this probability, or asexual, for high values.

  17. [Regulation of asexual reproduction in the planarian Dugesia tigrina].

    Science.gov (United States)

    Sheĭman, I M; Sakharova, N Iu; Tiras, Kh P; Shkutin, M F; Isaeva, V V

    2003-01-01

    We studied asexual reproduction of planarians under the natural and artificial photoperiodic conditions. It was shown that light inhibits the fission of planarians, while darkness stimulates it. The diurnal dynamics of the fission of planarians demonstrated a circadian rhythm. This rhythm is stable, which is expressed when the conditions are experimentally changed: constant darkness, unnatural rhythm of light-darkness succession). However, this stability is affected at the time zone change. The planarians are adapted to new conditions and begin to fission at once in correspondence with the new diurnal regime.

  18. Increasing transcultural awareness: the McMaster-Aga Khan-CIDA Project workshop model.

    Science.gov (United States)

    Smith, S E

    1997-01-01

    McMaster-Aga Khan-CIDA Project personnel at McMaster University School of Nursing over a period of four years designed and conducted eight one-day introductory workshops for nurses, faculty, staff, host families, and others involved with Pakistani nurses and Lady Health Visitors studying in Canada. The workshops (entitled Increasing Intercultural Awareness) assisted the Canadian and international participants to improve their awareness and knowledge of transcultural communication in preparation for working and socializing together. Using a participatory and active-learning approach, the workshop method introduced participants to transcultural communication; emphasized appreciation of cultural values, similarities and differences; and provided country-specific information on Pakistan. This article outlines the workshop design and rationale and describes specific examples of the transcultural nursing principles, practices, and teaching activities included in the one-day event.

  19. On the origin of asexual species by means of hybridization and drift

    DEFF Research Database (Denmark)

    Hartfield, Matthew

    2016-01-01

    Several species of asexuals appear to have existed for millions of years. This is despite the prevalent view that natural selection is weakened without gene exchange, which should cause these organisms to rapidly go extinct. In theory, one can identify evolutionary long-lived asexuals from...

  20. The exact distributions of F(IS under partial asexuality in small finite populations with mutation.

    Directory of Open Access Journals (Sweden)

    Solenn Stoeckel

    Full Text Available Reproductive systems like partial asexuality participate to shape the evolution of genetic diversity within populations, which is often quantified by the inbreeding coefficient F IS. Understanding how those mating systems impact the possible distributions of F IS values in theoretical populations helps to unravel forces shaping the evolution of real populations. We proposed a population genetics model based on genotypic states in a finite population with mutation. For populations with less than 400 individuals, we assessed the impact of the rates of asexuality on the full exact distributions of F IS, the probabilities of positive and negative F IS, the probabilities of fixation and the probabilities to observe changes in the sign of F IS over one generation. After an infinite number of generations, we distinguished three main patterns of effects of the rates of asexuality on genetic diversity that also varied according to the interactions of mutation and genetic drift. Even rare asexual events in mainly sexual populations impacted the balance between negative and positive F IS and the occurrence of extreme values. It also drastically modified the probability to change the sign of F IS value at one locus over one generation. When mutation prevailed over genetic drift, increasing rates of asexuality continuously increased the variance of F IS that reached its highest value in fully asexual populations. In consequence, even ancient asexual populations showed the entire F IS spectrum, including strong positive F IS. The prevalence of heterozygous loci only occurred in full asexual populations when genetic drift dominated.

  1. Evolution of asexuality via different mechanisms in grass thrips (Thysanoptra: Aptinothrips)

    NARCIS (Netherlands)

    van der Kooi, Casper J.; Schwander, Tanja

    2014-01-01

    Asexual lineages can derive from sexual ancestors via different mechanisms and at variable rates, which affects the diversity of the asexual population and thereby its ecological success. We investigated the variation and evolution of reproductive systems in Aptinothrips, a genus of grass thrips com

  2. Comparative toxicant sensitivity of sexual and asexual reproduction in the rotifer Brachionus calyciflorus

    Energy Technology Data Exchange (ETDEWEB)

    Snell, T.W. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Biology; Carmona, M.J. [Univ. de Valencia (Spain). Area de Ecologia

    1995-03-01

    Cyclically parthenogenetic zooplankters like rotifers are important tools for assessing toxicity in aquatic environments. Sexual reproduction is an essential component of rotifer life cycles, but current toxicity tests utilize only asexual reproduction. The authors compared the effects of four toxicants on asexual and sexual reproduction of the rotifer Brachionus calyciflorus. Toxicants had a differential effect on sexual and asexual reproduction, with sexual reproduction consistently the most sensitive. Concentrations of 0.2 {mu}g/ml PCP (sodium pentachlorophenate) had no effect on the asexual reproductive rate, but significantly reduced sexual reproduction. Likewise, chlorpyrifos concentrations of 0.3 {mu}g/ml had no significant effect on asexual reproduction, but sexual reproduction was significantly reduced. There was no difference in NOECs, LOECs, and chronic values for asexual and sexual reproduction for cadmium and naphthol tests. However, comparison of toxicant effect levels revealed that sexual reproduction was more strongly reduced at each toxicant concentration. The four toxicants tested inhibited sexual reproduction 2 to 68 times more than asexual reproduction at the lowest observed effect concentrations. Toxicants inhibited sexual reproduction in its initial step: sexual female production. Because sexual reproduction is more sensitive, toxicity tests based exclusively on asexual reproduction may not be protective of rotifer life cycles.

  3. Identification of Phytophthora sojae genes involved in asexual sporogenesis

    Indian Academy of Sciences (India)

    Ziying Wang; Xhaoxia Wang; Jie Shen; Guangyue Wang; Xiaoxi Zhu; Hongxia Lu

    2009-08-01

    To explore the molecular mechanisms involved in asexual spore development in Phytophthora sojae, the zoospores of strain PS26 were treated with ultraviolet (UV) irradiation. After selection, a mutant progeny, termed PS26-U03, was obtained and demonstrated to exhibit no oospore production. A suppression subtractive hybridization (SSH) approach was developed to investigate differences in gene expression between PS26 and PS26-U03 during asexual sporogenesis. Of the 126 sequences chosen for examination, 39 putative unigenes were identified that exhibit high expression in PS26. These sequences are predicted to encode proteins involved in metabolism, cell cycle, protein biosynthesis, cell signalling, cell defence, and transcription regulation. Seven clones were selected for temporal expression analysis using RT-PCR based on the results of the dot-blot screens. Three of the selected genes, developmental protein DG1037 (UB88), glycoside hydrolase (UB149) and a hypothetical protein (UB145), were expressed only in PS26, whereas the transcripts of phosphatidylinositol-4-phosphate 5-kinase (UB36), FAD-dependent pyridine nucleotide-disulphide oxidoreductase (UB226) and sugar transporter (UB256) were expressed at very low levels in PS26-U03 but at high levels in PS26.

  4. Sexual and asexual reproduction in the colonial ascidian Botryllus schlosseri.

    Science.gov (United States)

    Gasparini, Fabio; Manni, Lucia; Cima, Francesca; Zaniolo, Giovanna; Burighel, Paolo; Caicci, Federico; Franchi, Nicola; Schiavon, Filippo; Rigon, Francesca; Campagna, Davide; Ballarin, Loriano

    2015-01-01

    The colonial tunicate Botryllus schlosseri is a widespread filter-feeding ascidian that lives in shallow waters and is easily reared in aquaria. Its peculiar blastogenetic cycle, characterized by the presence of three blastogenetic generations (filtering adults, buds, and budlets) and by recurrent generation changes, has resulted in over 60 years of studies aimed at understanding how sexual and asexual reproduction are coordinated and regulated in the colony. The possibility of using different methodological approaches, from classical genetics to cell transplantation, contributed to the development of this species as a valuable model organism for the study of a variety of biological processes. Here, we review the main studies detailing rearing, staging methods, reproduction and colony growth of this species, emphasizing the asymmetry in sexual and asexual reproduction potential, sexual reproduction in the field and the laboratory, and self- and cross-fertilization. These data, opportunely matched with recent tanscriptomic and genomic outcomes, can give a valuable help to the elucidation of some important steps in chordate evolution.

  5. Skeletogenesis and asexual reproduction in the earliest biomineralizing animal Cloudina

    Science.gov (United States)

    Hua, Hong; Chen, Zhe; Yuan, Xunlai; Zhang, Luyi; Xiao, Shuhai

    2005-04-01

    The tubular fossil Cloudina is emerging as an important Ediacaran index fossil. However, its morphology, skeletogenesis, reproduction, and phylogenetic affinity have not been fully resolved. New material from the Dengying Formation of south China confirms that Cloudina tubes consist of eccentrically and sometimes deeply nested funnels and that the tubes lack transverse cross-walls, inconsistent with the traditional cone-in-cone morphological reconstruction. Tube walls are composed of micrometer-sized, more or less equant crystals. A number of Cloudina tubes branch dichotomously, in which daughter funnels split within parent ones. The Cloudina animal is interpreted to have been able to initiate biomineralization of new funnels within old ones. Its skeleton was probably secreted as calcite crystals suspended in organic matrix; the crystals do not appear to have nucleated and grown on a sheeted substrate. It was clearly capable of asexual reproduction, through budding within parent funnels rather than at the apertural end. The morphology, skeletogenesis, and asexual reproduction of Cloudina are broadly similar to modern serpulid annelids, indicating possible phylogenetic relationships or morphological convergence.

  6. The AGC Ser/Thr kinase Aga1 is essential for appressorium formation and maintenance of the actin cytoskeleton in the smut fungus Ustilago maydis.

    Science.gov (United States)

    Berndt, Patrick; Lanver, Daniel; Kahmann, Regine

    2010-12-01

    On the plant surface the dimorphic fungus Ustilago maydis switches from budding to hyphal growth and differentiates appressoria. To get more insight into these highly regulated processes we report on the role of a conserved Ser/Thr kinase of the AGC kinase family, Aga1. U. maydis Aga1 could functionally replace Ypk1p in Saccharomyces cerevisiae. aga1 deletion mutants were affected in growth, cell wall integrity, mating as well as the ability to form appressoria and showed defects in actin organization and actin-dependent endocytosis. With respect to appressorium formation and endocytosis, the aga1 deletion phenotype could be mimicked by inhibiting the formation of actin filaments with Latrunculin A. These data suggest a critical role of Aga1 in F-actin organization during the morphological changes accompanying the development of appressoria.

  7. PFRU, a single dominant locus regulates the balance between sexual and asexual plant reproduction in cultivated strawberry.

    Science.gov (United States)

    Gaston, Amèlia; Perrotte, Justine; Lerceteau-Köhler, Estelle; Rousseau-Gueutin, Mathieu; Petit, Aurélie; Hernould, Michel; Rothan, Christophe; Denoyes, Béatrice

    2013-04-01

    Strawberry (Fragaria sp.) stands as an interesting model for studying flowering behaviour and its relationship with asexual plant reproduction in polycarpic perennial plants. Strawberry produces both inflorescences and stolons (also called runners), which are lateral stems growing at the soil surface and producing new clone plants. In this study, the flowering and runnering behaviour of two cultivated octoploid strawberry (Fragaria × ananassa Duch., 2n = 8× = 56) genotypes, a seasonal flowering genotype CF1116 and a perpetual flowering genotype Capitola, were studied along the growing season. The genetic bases of the perpetual flowering and runnering traits were investigated further using a pseudo full-sibling F1 population issued from a cross between these two genotypes. The results showed that a single major quantitative trait locus (QTL) named FaPFRU controlled both traits in the cultivated octoploid strawberry. This locus was not orthologous to the loci affecting perpetual flowering (SFL) and runnering (R) in Fragaria vesca, therefore suggesting different genetic control of perpetual flowering and runnering in the diploid and octoploid Fragaria spp. Furthermore, the FaPFRU QTL displayed opposite effects on flowering (positive effect) and on runnering (negative effect), indicating that both traits share common physiological control. These results suggest that this locus plays a major role in strawberry plant fitness by controlling the balance between sexual and asexual plant reproduction.

  8. Origin, divergence, and phylogeny of asexual Epichloë endophyte in Elymus species from western China.

    Science.gov (United States)

    Song, Hui; Nan, Zhibiao

    2015-01-01

    Asexual Epichloë species are likely derived directly from sexual Epichloë species that then lost their capacity for sexual reproduction or lost sexual reproduction because of interspecific hybridization between distinct lineages of sexual Epichloë and/or asexual Epichloë species. In this study we isolated asexual Epichloë endophytes from Elymus species in western China and sequenced intron-rich regions in the genes encoding β-tubulin (tubB) and translation elongation factor 1-α (tefA). Our results showed that there are no gene copies of tubB and tefA in any of the isolates. Phylogenetic analysis showed that sequences in this study formed a single clade with asexual Epichloë bromicola from Hordeum brevisubulatum, which implies asexual Epichloë endophytes that are symbionts in a western Chinese Elymus species likely share a common ancestor with asexual E. bromicola from European H. brevisubulatum. In addition, our results revealed that asexual E. bromicola isolates that are symbionts in a western Chinese Elymus species and sexual Epichloë species that are symbionts in a North American Elymus species have a different origin. Further analysis found that Epichloë species likely originated in Eurasia. In addition, the results support the hypothesis that migratory birds or humans might have aided the dispersal of these fungal endophytes to other continents.

  9. Origin, divergence, and phylogeny of asexual Epichloe endophyte in Elymus species from western China.

    Directory of Open Access Journals (Sweden)

    Hui Song

    Full Text Available Asexual Epichloë species are likely derived directly from sexual Epichloë species that then lost their capacity for sexual reproduction or lost sexual reproduction because of interspecific hybridization between distinct lineages of sexual Epichloë and/or asexual Epichloë species. In this study we isolated asexual Epichloë endophytes from Elymus species in western China and sequenced intron-rich regions in the genes encoding β-tubulin (tubB and translation elongation factor 1-α (tefA. Our results showed that there are no gene copies of tubB and tefA in any of the isolates. Phylogenetic analysis showed that sequences in this study formed a single clade with asexual Epichloë bromicola from Hordeum brevisubulatum, which implies asexual Epichloë endophytes that are symbionts in a western Chinese Elymus species likely share a common ancestor with asexual E. bromicola from European H. brevisubulatum. In addition, our results revealed that asexual E. bromicola isolates that are symbionts in a western Chinese Elymus species and sexual Epichloë species that are symbionts in a North American Elymus species have a different origin. Further analysis found that Epichloë species likely originated in Eurasia. In addition, the results support the hypothesis that migratory birds or humans might have aided the dispersal of these fungal endophytes to other continents.

  10. The paf gene product modulates asexual development in Penicillium chrysogenum.

    Science.gov (United States)

    Hegedüs, Nikoletta; Sigl, Claudia; Zadra, Ivo; Pócsi, Istvan; Marx, Florentine

    2011-06-01

    Penicillium chrysogenum secretes a low molecular weight, cationic and cysteine-rich protein (PAF). It has growth inhibitory activity against the model organism Aspergillus nidulans and numerous zoo- and phytopathogenic fungi but shows only minimal conditional antifungal activity against the producing organism itself. In this study we provide evidence for an additional function of PAF which is distinct from the antifungal activity against putative ecologically concurrent microorganisms. Our data indicate that PAF enhances conidiation in P. chrysogenum by modulating the expression of brlA, the central regulatory gene for mitospore development. A paf deletion strain showed a significant impairment of mitospore formation which sustains our hypothesis that PAF plays an important role in balancing asexual differentiation in P. chrysogenum.

  11. Overexpression and secretion of AgaA7 from Pseudoalteromonas hodoensis sp. nov in Bacillus subtilis for the depolymerization of agarose.

    Science.gov (United States)

    Ramos, Kristine Rose M; Valdehuesa, Kris Niño G; Cabulong, Rhudith B; Moron, Llewelyn S; Nisola, Grace M; Hong, Soon-Kwang; Lee, Won-Keun; Chung, Wook-Jin

    2016-08-01

    Interest in agar or agarose-based pharmaceutical products has driven the search for potent agarolytic enzymes. An extracellular β-agarase (AgaA7) recently isolated from Pseudoalteromonas hodoensis sp. nov was expressed in Bacillus subtilis, which was chosen due to its capability to overproduce and secrete functional enzymes. Phenotypic analysis showed that the engineered B. subtilis secreted a functional AgaA7 when fused with the aprE signal peptide (SP) at the amino-terminus. The maximum agarolytic activity was observed during the late logarithmic phase. To further improve the secretion of AgaA7, an expression library of AgaA7 fused to different naturally occurring B. subtilis SPs was created. The amount of AgaA7 secreted by the clones was compared through activity assay, immuno-blot, and purification via affinity chromatography. Although the aprE SP can readily facilitate the secretion of AgaA7, other SPs such as yqgA, pel, and lipA were relatively more efficient. Among these SPs, lipA was the most efficient in improving the secretion of AgaA7.The use of B. subtilis as host for the expression and secretion of agarolytic and other hydrolytic enzymes can be a useful tool in the field of white biotechnology.

  12. Cloning, Expression, and Biochemical Characterization of a Novel Acidic GH16 β-Agarase, AgaJ11, from Gayadomonas joobiniege G7.

    Science.gov (United States)

    Jung, Subin; Jeong, Byeong-Chul; Hong, Soon-Kwang; Lee, Chang-Ro

    2017-03-01

    A novel β-agarase AgaJ11 belonging to the glycoside hydrolase (GH) 16 family was identified from an agar-degrading bacterium Gayadomonas joobiniege G7. AgaJ11 was composed of 317 amino acids (35 kDa), including a 26-amino acid signal peptide, and had the highest similarity (44 % identity) to a putative β-agarase from an agarolytic marine bacterium Agarivorans albus MKT 106. The agarase activity of purified AgaJ11 was confirmed by zymogram analysis. The optimum pH and temperature for AgaJ11 activity were determined to be 4.5 and 40 °C, respectively. Notably, AgaJ11 is an acidic β-agarase that was active only at a narrow pH range from 4 to 5, and less than 30 % of its enzymatic activity was retained at other pH conditions. The K m and V max of AgaJ11 for agarose were 21.42 mg/ml and 25 U/mg, respectively. AgaJ11 did not require metal ions for its activity, but severe inhibition by several metal ions was observed. Thin layer chromatography and agarose-liquefying analyses revealed that AgaJ11 is an endo-type β-agarase that hydrolyzes agarose into neoagarohexaose, neoagarotetraose, and neoagarobiose. Therefore, this study shows that AgaJ11 from G. joobiniege G7 is a novel GH16 β-agarase with an acidic enzymatic feature that may be useful for industrial applications.

  13. Morbility, clinical data and proteomic analysis of IUGR and AGA newborns at different gestational ages

    Directory of Open Access Journals (Sweden)

    M.D. Ruiz-González

    2016-12-01

    Full Text Available The data are related to the proteomic analysis of 43 newborns with intrauterine growth retardation (IUGR and 45 newborns with appropriate weight for gestational age (AGA carried out by separation via 2DE and analyzed by MS–TOF/TOF. All newborns were separated into three gestational age groups, "Very Preterm" 29–32 weeks, "Moderate Preterm" 33–36 weeks, and, "Term" ≥37weeks. From each newborn, blood was drawn three times from birth to 1 month life. High-abundant serum proteins were depleted, and the minority ones were separated by 2DE and analyzed for significant expression differences. The data reflect analytic and clinic variables analyzed globally and categorized by gestational age in relation to IUGR and the optimization of conditions for 2-DE separation. The data from this study are related to the research article entitled "Alterations of Protein Expression in Serum of Infants with Intrauterine Growth Restriction and Different Gestational Ages" (M.D. Ruis-González, M.D. Cañete, J.L. Gómez-Chaparro, N. Abril, R. Cañete, J. López-Barea, 2015 [1]. The present dataset of serum IUGR newborn proteome can be used as a reference for any study involving intrauterine growth restriction during the first month of life.

  14. Students’ perception of educational environment at Aga Khan University Medical College, Karachi, Pakistan

    Science.gov (United States)

    Rehman, Rehana; Ghias, Kulsoom; Fatima, Syeda Sadia; Hussain, Mehwish; Alam, Faiza

    2016-01-01

    Objective: To assess educational environment in Aga Khan University Medical College (AKUMC) by Dundee Ready Educational Environmental Measure (DREEM) scale. Methods: A cross-sectional survey of students at the AKUMC with simple random sampling was carried out from June 2014 till March 2015. Responses in five subscales were used to calculate DREEM scores. Results: The average DREEM score was 125.77±16.8 with a reliability of 91.3%. With regards to subscales, on the 12-item students’ perceptions of learning (PoL) subscale, the maximum score was 48; 11 items of students’ perceptions of teachers (PoT) had a maximum score of 44; students’ academic self-perceptions (ASP) identified by 8 items showed maximum score of 32; students’ perceptions of atmosphere (PoA) with 12 items obtained maximum score 48 and students’ social self-perceptions (SSP) subscale of 7 items had a maximum score of 28. Conclusion: Students perceived a positive learning environment at AKUMC Karachi. PMID:27375721

  15. The gynogenetic reproduction of diploid and triploid hybrid spined loaches (Cobitis: Teleostei), and their ability to establish successful clonal lineages--on the evolution of polyploidy in asexual vertebrates.

    Science.gov (United States)

    Janko, Karel; Bohlen, Jörg; Lamatsch, Dunja; Flajshans, Martin; Epplen, Jörg T; Ráb, Petr; Kotlík, Petr; Slechtová, Vera

    2007-10-01

    Polyploidisation is assumed to have played a significant role in the evolution of hybrid asexual lineages. The virtual absence of natural asexual systems in which more than a single ploidy level successfully establishes successful independent clonal lineages is generally explained by the strong effects of polyploidisation on fitness. Experimental crosses were made between diploid and triploid asexual Cobitis elongatoides x C. taenia hybrids (female) and both parental spined loach species (male). Genotyping of the progeny using allozymes and multilocus DNA fingerprinting, along with flow cytometric measurement of ploidy level, demonstrated the occurrence of gynogenetic reproduction in both female biotypes. The incorporation of the sperm genome occurred in some progeny, giving rise to a higher ploidy level, but the rate of polyploidisation differed significantly between the diploid and triploid females. These outcomes are consistent with the existence of developmental constraints on tetraploidy, which determine the rarity of tetraploids in natural populations. No cases of ploidy level reduction were observed. Since diploid and triploid hybrid populations occur where the lack of potential progenitor excludes the possibility of de novo origin, it is probable that both diploid and triploid females can establish successful clonal lineages. Spined loaches represent a unique example, among asexual vertebrates, where more than one ploidy level can establish persistent clonal lineages, which are reproductively independent of one another.

  16. Natural epigenetic variation contributes to heritable flowering divergence in a widespread asexual dandelion lineage

    NARCIS (Netherlands)

    Wilschut, Rutger; Oplaat, C.; Snoek, L.B.; Kirschner, J.; Verhoeven, K.J.F.

    2016-01-01

    Epigenetic variation has been proposed to contribute to the success of asexual plants, either as a contributor to phenotypic plasticity or by enabling transient adaptation via selection on transgenerationally stable, but reversible, epialleles. While recent studies in experimental plant populations

  17. Fitness club

    CERN Multimedia

    Fitness club

    2011-01-01

    General fitness Classes Enrolments are open for general fitness classes at CERN taking place on Monday, Wednesday, and Friday lunchtimes in the Pump Hall (building 216). There are shower facilities for both men and women. It is possible to pay for 1, 2 or 3 classes per week for a minimum of 1 month and up to 6 months. Check out our rates and enrol at: http://cern.ch/club-fitness Hope to see you among us! CERN Fitness Club fitness.club@cern.ch  

  18. Sexual versus Asexual Reproduction: Distinct Outcomes in Relative Abundance of Parthenogenetic Mealybugs following Recent Colonization.

    Science.gov (United States)

    Tabata, Jun; Ichiki, Ryoko T; Tanaka, Hirotaka; Kageyama, Daisuke

    2016-01-01

    Asexual reproduction, including parthenogenesis in which embryos develop within a female without fertilization, is assumed to confer advantages over sexual reproduction, which includes a "cost of males." Sexual reproduction largely predominates in animals, however, indicating that this cost is outweighed by the genetic and/or ecological benefits of sexuality, including the acquisition of advantageous mutations occurring in different individuals and the elimination of deleterious mutations. But the evolution of sexual reproduction remains unclear, because we have limited examples that demonstrate the relative success of sexual lineages in the face of competition from asexual lineages in the same environment. Here we investigated a sympatric occurrence of sexual and asexual reproduction in the pineapple mealybug, Dysmicoccus brevipes. This pest invaded southwestern Japan, including Okinawa and Ishigaki Islands, in the 1930s in association with imported pineapple plants. Our recent censuses demonstrated that on Okinawa sexually reproducing individuals can coexist with and even dominate asexual individuals in the presence of habitat and resource competition, which is considered to be severe for this nearly immobile insect. Molecular phylogeny based on partial DNA sequences in the mitochondrial and nuclear genomes, as well as the endosymbiotic bacterial genome, revealed that the asexual lineage diverged from a common sexual ancestor in the relatively recent past. In contrast, only the asexual lineage exhibiting obligate apomictic thelytoky was discovered on Ishigaki. Co-existence of the two lineages cannot be explained by the results of laboratory experiments, which showed that the intrinsic rate of increase in the sexual lineage was not obviously superior to that of the asexual lineage. Differences in biotic and/or abiotic selective forces operating on the two islands might be the cause of this discrepancy. This biological system offers a unique opportunity to assess

  19. Sexual versus Asexual Reproduction: Distinct Outcomes in Relative Abundance of Parthenogenetic Mealybugs following Recent Colonization.

    Directory of Open Access Journals (Sweden)

    Jun Tabata

    Full Text Available Asexual reproduction, including parthenogenesis in which embryos develop within a female without fertilization, is assumed to confer advantages over sexual reproduction, which includes a "cost of males." Sexual reproduction largely predominates in animals, however, indicating that this cost is outweighed by the genetic and/or ecological benefits of sexuality, including the acquisition of advantageous mutations occurring in different individuals and the elimination of deleterious mutations. But the evolution of sexual reproduction remains unclear, because we have limited examples that demonstrate the relative success of sexual lineages in the face of competition from asexual lineages in the same environment. Here we investigated a sympatric occurrence of sexual and asexual reproduction in the pineapple mealybug, Dysmicoccus brevipes. This pest invaded southwestern Japan, including Okinawa and Ishigaki Islands, in the 1930s in association with imported pineapple plants. Our recent censuses demonstrated that on Okinawa sexually reproducing individuals can coexist with and even dominate asexual individuals in the presence of habitat and resource competition, which is considered to be severe for this nearly immobile insect. Molecular phylogeny based on partial DNA sequences in the mitochondrial and nuclear genomes, as well as the endosymbiotic bacterial genome, revealed that the asexual lineage diverged from a common sexual ancestor in the relatively recent past. In contrast, only the asexual lineage exhibiting obligate apomictic thelytoky was discovered on Ishigaki. Co-existence of the two lineages cannot be explained by the results of laboratory experiments, which showed that the intrinsic rate of increase in the sexual lineage was not obviously superior to that of the asexual lineage. Differences in biotic and/or abiotic selective forces operating on the two islands might be the cause of this discrepancy. This biological system offers a unique

  20. Toxic effects of bisphenol A on sexual and asexual reproduction in Hydra oligactis.

    Science.gov (United States)

    Fukuhori, N; Kitano, M; Kimura, H

    2005-05-01

    Hydra oligactis, an evolutionarily primitive invertebrate, produced eggs or testes (sexual reproduction) when starved at 10 degrees C, and produced buds (asexual reproduction) when fed at 20 degrees C. Bisphenol A (BPA) at 2-4 mg/L given to male or female hydra had adverse effects on both sexual and asexual reproduction. Despite the estrogenic nature of BPA, testis formation and egg formation were similarly affected. The doses causing these acute toxicities were comparable to those reported earlier in aquatic invertebrates and were much higher than environmentally detected doses, at which the disruption of the endocrine system has been reported in fishes. All these facts indicate that the adverse effects are the results of general toxicity and may not be due to the estrogenic function of the compound. On the other hand, we found that BPA at 1 mg/L (a dose still much higher than environmental doses) stimulated asexual reproduction. No such stimulation of sexual reproduction was seen. When male hydras were fed at 10 degrees C, they produced both buds and testes simultaneously. BPA at 0.5 and 1 mg/L under this condition also stimulated asexual reproduction, whereas it suppressed sexual reproduction more severely than BPA at 2-3 mg/L. There may be some interaction between processes involved in sexual and asexual reproduction under this condition, and the stimulation of asexual reproduction by BPA may cause suppression of sexual reproduction.

  1. Molecular phylogenetics and asexuality in the brine shrimp Artemia.

    Science.gov (United States)

    Baxevanis, Athanasios D; Kappas, Ilias; Abatzopoulos, Theodore J

    2006-09-01

    Explaining cases of long-term persistence of parthenogenesis has proven an arduous task for evolutionary biologists. Interpreting sexual-asexual interactions though has recently advanced owing to methodological design, increased taxon sampling and choice of model organisms. We inferred the phylogeny of Artemia, a halophilic branchiopod genus of sexual and parthenogenetic forms with cosmopolitan distribution, marked geographic patterns and ecological partitioning. Joint analysis of newly derived ITS1 sequences and 16S RFLP markers from global isolates indicates significant interspecific divergence as well as pronounced diversity for parthenogens, matching that of sexual ancestors. Maximum parsimony, maximum likelihood, and Bayesian methods were largely congruent in reconstructing the phylogeny of the genus. Given the current sampling, at least four independent origins of parthenogenesis are deduced. Molecular clock calibrations based on biogeographic landmarks indicate that the lineage leading to A. persimilis diverged from the common ancestor of all Artemia species between 80 and 90 MYA at the time of separation of Africa from South America, whereas parthenogenesis first appeared at least 3 MYA. Common mitochondrial DNA haplotypes delineate A. urmiana and A. tibetiana as possible maternal parents of several clonal lineages. A novel topological placement of A. franciscana as a sister clade to all Asian Artemia and parthenogenetic forms is proposed and also supported by ITS1 length and other existing data.

  2. The genetic control of apomixis: asexual seed formation.

    Science.gov (United States)

    Hand, Melanie L; Koltunow, Anna M G

    2014-06-01

    Apomixis (asexual seed formation) is the result of a plant gaining the ability to bypass the most fundamental aspects of sexual reproduction: meiosis and fertilization. Without the need for male fertilization, the resulting seed germinates a plant that develops as a maternal clone. This dramatic shift in reproductive process has been documented in many flowering plant species, although no major seed crops have been shown to be capable of apomixis. The ability to generate maternal clones and therefore rapidly fix desirable genotypes in crop species could accelerate agricultural breeding strategies. The potential of apomixis as a next-generation breeding technology has contributed to increasing interest in the mechanisms controlling apomixis. In this review, we discuss the progress made toward understanding the genetic and molecular control of apomixis. Research is currently focused on two fronts. One aims to identify and characterize genes causing apomixis in apomictic species that have been developed as model species. The other aims to engineer or switch the sexual seed formation pathway in non-apomictic species, to one that mimics apomixis. Here we describe the major apomictic mechanisms and update knowledge concerning the loci that control them, in addition to presenting candidate genes that may be used as tools for switching the sexual pathway to an apomictic mode of reproduction in crops.

  3. Ultrastructural changes during asexual multiple reproduction in Trichomonas vaginalis.

    Science.gov (United States)

    Yusof, A; Kumar, S

    2012-05-01

    Trichomonas vaginalis, a flagellated protozoan parasite, is commonly found in the genitourinary tract of humans. Its mode of reproduction has always been reported to be binary fission. The high parasite numbers seen in a relatively short period in in vitro cultures led us to believe that there must be other modes of reproduction. The present study for the first time provides transformational evidence at the ultrastructural level seen in tropohozoites of T. vaginalis undergoing a multiple asexual mode of reproduction. The findings show that the single cell with a nucleus is capable of dividing to as many as eight nuclei within the cytoplasmic body. Before the commencement of division, the nucleus remained round or ovoid in shape with condensed chromatin masses and only a few endoplasmic reticula surrounding the nucleus. During the division, the nucleus started to elongate and become irregular in shape with visible chromatin masses condensing with the accumulation of numerous endoplasmic reticula. Nuclear division gave rise to as many as eight nuclei within a cell, which could be seen to be connected by numerous endoplasmic reticula. In addition, a high number of hydrogenosomes and vacuoles can be seen in multinucleated T. vaginalis compared with single nucleated T. vaginalis. This study confirms that multiple modes of nuclear division do exist in T. vaginalis and are a precursor to progeny formation.

  4. Fitness Club

    CERN Multimedia

    Fitness Club

    2011-01-01

    The CERN Fitness Club is organising Zumba Classes on the first Wednesday of each month, starting 7 September (19.00 – 20.00). What is Zumba®? It’s an exhilarating, effective, easy-to-follow, Latin-inspired, calorie-burning dance fitness-party™ that’s moving millions of people toward joy and health. Above all it’s great fun and an excellent work out. Price: 22 CHF/person Sign-up via the following form: https://espace.cern.ch/club-fitness/Lists/Zumba%20Subscription/NewForm.aspx For more info: fitness.club@cern.ch

  5. Sexual and asexual oogenesis require the expression of unique and shared sets of genes in the insect Acyrthosiphon pisum

    Directory of Open Access Journals (Sweden)

    Gallot Aurore

    2012-02-01

    Full Text Available Abstract Background Although sexual reproduction is dominant within eukaryotes, asexual reproduction is widespread and has evolved independently as a derived trait in almost all major taxa. How asexuality evolved in sexual organisms is unclear. Aphids, such as Acyrthosiphon pisum, alternate between asexual and sexual reproductive means, as the production of parthenogenetic viviparous females or sexual oviparous females and males varies in response to seasonal photoperiodism. Consequently, sexual and asexual development in aphids can be analyzed simultaneously in genetically identical individuals. Results We compared the transcriptomes of aphid embryos in the stages of development during which the trajectory of oogenesis is determined for producing sexual or asexual gametes. This study design aimed at identifying genes involved in the onset of the divergent mechanisms that result in the sexual or asexual phenotype. We detected 33 genes that were differentially transcribed in sexual and asexual embryos. Functional annotation by gene ontology (GO showed a biological signature of oogenesis, cell cycle regulation, epigenetic regulation and RNA maturation. In situ hybridizations demonstrated that 16 of the differentially-transcribed genes were specifically expressed in germ cells and/or oocytes of asexual and/or sexual ovaries, and therefore may contribute to aphid oogenesis. We categorized these 16 genes by their transcription patterns in the two types of ovaries; they were: i expressed during sexual and asexual oogenesis; ii expressed during sexual and asexual oogenesis but with different localizations; or iii expressed only during sexual or asexual oogenesis. Conclusions Our results show that asexual and sexual oogenesis in aphids share common genetic programs but diverge by adapting specificities in their respective gene expression profiles in germ cells and oocytes.

  6. Sexual and Asexual Reproduction of Salix sitchensis and the Influence of Beaver (Castor canadensis) Herbivory on Reproductive Success

    OpenAIRE

    Travis G. Gerwing; Alyssa M. Allen Gerwing; Rapaport, Eric; Alström-Rapaport, Cecilia

    2012-01-01

    The influence of beaver (Castor canadensis Kuhl) herbivory on Salix reproduction, specifically the stimulation of asexual reproduction via browsed stem fragments, is relatively unknown. This study aimed to determine if beaver herbivory stimulates asexual reproduction of riparian willows and results in mature populations dominated by clones. The survival of seedlings and asexual propagules produced by beaver browse in populations of the riparian willow Salix sitchensis (Sanson in Bongard) were...

  7. Advantage or Disadvantage: Is Asexual Reproduction Beneficial to Survival of the Tunicate, Polyandrocarpa misakiensis.

    Science.gov (United States)

    Kawamura, K; Fujiwara, S

    2000-04-01

    It has been believed that clonal propagation by asexual reproduction has serious disadvantages for long-term survival, because asexual reproduction seems not to remove harmful mutations, it seems not to give rise to genetic variations upon which evolution depends and it seems not to reset cell aging. In this article, we re-consider those arguments, by reviewing asexual reproduction of the tunicate, Polyandrocarpa misakiensis. Tracer experiments of bud formation and growth using morphological and chimeric phenotypes showed that the parental epithelial tissues surrounding the bud primordium do not enter the growing bud. It is possible, therefore, to assume that budding involves the purge of a large number of parental somatic cells and tissues. Unlike sexuals, asexuals do not carry out meiotic recombination nor gene shuffling that are two major sources of genetic variation, but we can show that in P. misakiensis at least two genes have significant redundancy and genetic variation even in a clonal colony. Telomerase expressed in germlines is thought to reset the molecular clock executed by telomere shortening. In our Polyandrocarpa cDNA projects, four out of about 2,000 cDNAs examined were matched with retroviral reverse transcriptase that is the catalytic subunit of telomerase, suggesting that telomerase might work in asexual reproduction. In P. misakiensis, dedifferentiation system is used to make new asexual generations. TC14 lectin plays an important role in the maintenance of multipotent but differentiated state of the formative tissue. It is antagonized by tunicate serine protease (TRAMP) that has striking mitogenic and dedifferentiation-inducing activities on the multipotent cells. This system would serve to delay aging of somatic cells. In conclusion, empirical arguments that asexual reproduction is disadvantageous to long-term life do not appear to be tenable to budding of P. misakiensis.

  8. Discordance between nuclear and mitochondrial genomes in sexual and asexual lineages of the freshwater snail Potamopyrgus antipodarum.

    Science.gov (United States)

    Paczesniak, Dorota; Jokela, Jukka; Larkin, Katelyn; Neiman, Maurine

    2013-09-01

    The presence and extent of mitonuclear discordance in coexisting sexual and asexual lineages provides insight into 1) how and when asexual lineages emerged, and 2) the spatial and temporal scales at which the ecological and evolutionary processes influencing the evolution of sexual and asexual reproduction occur. Here, we used nuclear single-nucleotide polymorphism (SNP) markers and a mitochondrial gene to characterize phylogeographic structure and the extent of mitonuclear discordance in Potamopyrgus antipodarum. This New Zealand freshwater snail is often used to study the evolution and maintenance of sex because obligately sexual and obligately asexual individuals often coexist. While our data indicate that sexual and asexual P. antipodarum sampled from the same lake population are often genetically similar, suggesting recent origin of these asexuals from sympatric sexual P. antipodarum, we also found significantly more population structure in sexuals vs. asexuals. This latter result suggests that some asexual lineages originated in other lakes and/or in the relatively distant past. When comparing mitochondrial and nuclear population genetic structure, we discovered that one mitochondrial haplotype ('1A') was rare in sexuals, but common and widespread in asexuals. Haplotype 1A frequency and nuclear genetic diversity were not associated, suggesting that the commonness of this haplotype cannot be attributed entirely to genetic drift and pointing instead to a role for selection.

  9. Horizontal transfer generates genetic variation in an asexual pathogen

    Directory of Open Access Journals (Sweden)

    Xiaoqiu Huang

    2014-10-01

    Full Text Available There are major gaps in the understanding of how genetic variation is generated in the asexual pathogen Verticillium dahliae. On the one hand, V. dahliae is a haploid organism that reproduces clonally. On the other hand, single-nucleotide polymorphisms and chromosomal rearrangements were found between V. dahliae strains. Lineage-specific (LS regions comprising about 5% of the genome are highly variable between V. dahliae strains. Nonetheless, it is unknown whether horizontal gene transfer plays a major role in generating genetic variation in V. dahliae. Here, we analyzed a previously sequenced V. dahliae population of nine strains from various geographical locations and hosts. We found highly homologous elements in LS regions of each strain; LS regions of V. dahliae strain JR2 are much richer in highly homologous elements than the core genome. In addition, we discovered, in LS regions of JR2, several structural forms of nonhomologous recombination, and two or three homologous sequence types of each form, with almost each sequence type present in an LS region of another strain. A large section of one of the forms is known to be horizontally transferred between V. dahliae strains. We unexpectedly found that 350 kilobases of dynamic LS regions were much more conserved than the core genome between V. dahliae and a closely related species (V. albo-atrum, suggesting that these LS regions were horizontally transferred recently. Our results support the view that genetic variation in LS regions is generated by horizontal transfer between strains, and by chromosomal reshuffling reported previously.

  10. Light-regulated asexual reproduction in Paecilomyces fumosoroseus.

    Science.gov (United States)

    Sánchez-Murillo, Rosa Icela; de la Torre-Martínez, Mayra; Aguirre-Linares, Jesús; Herrera-Estrella, Alfredo

    2004-02-01

    The entomopathogenic fungus Paecilomyces fumosoroseus has been successfully used in the control of several insect pests. Asexually produced spores (conidia) are the means for dispersal and transmission of the entomopathogen; upon contact with the insect cuticle they germinate and penetrate the host. In model fungal systems it has been found that phototropism, resetting of the circadian rhythm, the induction of carotenogenesis and the development of reproductive structures are controlled by blue light. The effect of light quality on conidial yield of P. fumosoroseus was investigated. Incubation in total darkness resulted in continued vegetative growth and lack of reproductive structures. In contrast, growth of the fungus in continuous illumination or under a night-day regime resulted in prolific formation of conidiophores bearing abundant mature conidia. Conidiation was photoinduced in competent mycelia by a single pulse of blue light and colonies were competent only after they had grown at least 72 h under total darkness. The fluence-response curves generated with blue light indicated that the minimal fluence required for the photomorphogenetic response was 180 micro mol m(-2) and the half-maximal response was at 400 micro mol m(-2). A fluence of 540 micro mol m(-2) was enough to saturate the system, inducing the maximum production of 2.12x10(8) conidia per colony. Higher light intensities markedly decreased conidiation, suggesting the occurrence of a process of adaptation. The authors propose the existence of a dual light-perception system with at least two photoreceptors in P. fumosoroseus, one promoting and one inhibiting conidiation.

  11. Infection dynamics in coexisting sexual and asexual host populations: support for the Red Queen hypothesis.

    Science.gov (United States)

    Vergara, Daniela; Jokela, Jukka; Lively, Curtis M

    2014-08-01

    The persistence of sexual reproduction is a classic problem in evolutionary biology. The problem stems from the fact that, all else equal, asexual lineages should rapidly replace coexisting sexual individuals due to the cost of producing males in sexual populations. One possible countervailing advantage to sexual reproduction is that, on average, outcrossed offspring are more resistant than common clones to coevolving parasites, as predicted under the Red Queen hypothesis. In this study, we evaluated the prevalence of infection by a sterilizing trematode (Microphallus sp.) in a natural population of freshwater snails that was composed of both sexual and asexual individuals (Potamopyrgus antipodarum). More specifically, we compared the frequency of infection in sexual and asexual individuals over a 5-year period at four sites at a natural glacial lake (Lake Alexandrina, South Island, New Zealand). We found that at most sites and over most years, the sexual population was less infected than the coexisting asexual population. Moreover, the frequency of uninfected sexual females was periodically greater than two times the frequency of uninfected asexual females. These results give clear support for a fluctuating parasite-mediated advantage to sexual reproduction in a natural population.

  12. Exploring the role of asexual multiplication in poplar rust epidemics: impact on diversity and genetic structure.

    Science.gov (United States)

    Barrès, Benoît; Dutech, Cyril; Andrieux, Axelle; Halkett, Fabien; Frey, Pascal

    2012-10-01

    Fungal plant pathogens, especially rust fungi (Pucciniales), are well known for their complex life cycles, which include phases of sexual and asexual reproduction. The effect of asexual multiplication on population genetic diversity has been investigated in the poplar rust fungus Melampsora larici-populina using a nested hierarchical sampling scheme. Four hierarchical levels were considered: leaf, twig, tree and site. Both cultivated and wild poplar stands were sampled at two time points at the start and end of rust epidemics. A total of 641 fungal isolates was analysed using nine microsatellite markers. This study revealed that the genetic signature of asexual multiplication in the wild poplar stand was seen only at lower hierarchical levels (leaf and twig). Moreover, we observed an erosion of clonal structure through time, with an increase in both gene and genotypic diversity. New genotypes contributed to host infection over time, which demonstrates the importance of allo-infection in the epidemic process in this host-pathogen system. Compared with the wild stands, the nearly lack of detection of clonal structure in the cultivated stands reflects the higher infection level on cultivated poplars. More generally, this genetic analysis illustrates the utility of population genetics approach for elucidating the proportion of asexual reproduction in the multiplication of isolates during an epidemic, and for proper quantification of asexual dispersal in plant pathogens.

  13. Neutral and selection-driven decay of sexual traits in asexual stick insects.

    Science.gov (United States)

    Schwander, Tanja; Crespi, Bernard J; Gries, Regine; Gries, Gerhard

    2013-08-07

    Environmental shifts and lifestyle changes may result in formerly adaptive traits becoming non-functional or maladaptive. The subsequent decay of such traits highlights the importance of natural selection for adaptations, yet its causes have rarely been investigated. To study the fate of formerly adaptive traits after lifestyle changes, we evaluated sexual traits in five independently derived asexual lineages, including traits that are specific to males and therefore not exposed to selection. At least four of the asexual lineages retained the capacity to produce males that display normal courtship behaviours and are able to fertilize eggs of females from related sexual species. The maintenance of male traits may stem from pleiotropy, or from these traits only regressing via drift, which may require millions of years to generate phenotypic effects. By contrast, we found parallel decay of sexual traits in females. Asexual females produced altered airborne and contact signals, had modified sperm storage organs, and lost the ability to fertilize their eggs, impeding reversals to sexual reproduction. Female sexual traits were decayed even in recently derived asexuals, suggesting that trait changes following the evolution of asexuality, when they occur, proceed rapidly and are driven by selective processes rather than drift.

  14. Fitness Club

    CERN Multimedia

    Fitness Club

    2012-01-01

    Open to All: http://cern.ch/club-fitness  fitness.club@cern.ch Boxing Your supervisor makes your life too tough ! You really need to release the pressure you've been building up ! Come and join the fit-boxers. We train three times a week in Bd 216, classes for beginners and advanced available. Visit our website cern.ch/Boxing General Fitness Escape from your desk with our general fitness classes, to strengthen your heart, muscles and bones, improve you stamina, balance and flexibility, achieve new goals, be more productive and experience a sense of well-being, every Monday, Wednesday and Friday lunchtime, Tuesday mornings before work and Thursday evenings after work – join us for one of our monthly fitness workshops. Nordic Walking Enjoy the great outdoors; Nordic Walking is a great way to get your whole body moving and to significantly improve the condition of your muscles, heart and lungs. It will boost your energy levels no end. Pilates A body-conditioning technique de...

  15. The Key Role of Epigenetics in the Persistence of Asexual Lineages

    Directory of Open Access Journals (Sweden)

    Emilie Castonguay

    2012-01-01

    Full Text Available Asexual organisms, often perceived as evolutionary dead ends, can be long-lived and geographically widespread. We propose that epigenetic mechanisms could play a crucial role in the evolutionary persistence of these lineages. Genetically identical organisms could rely on phenotypic plasticity to face environmental variation. Epigenetic modifications could be the molecular mechanism enabling such phenotypic plasticity; they can be influenced by the environment and act at shorter timescales than mutation. Recent work on the asexual vertebrate Chrosomus eos-neogaeus (Pisces: Cyprinidae provides broad insights into the contribution of epigenetics in genetically identical individuals. We discuss the extension of these results to other asexual organisms, in particular those resulting from interspecific hybridizations. We finally develop on the evolutionary relevance of epigenetic variation in the context of heritability.

  16. Oxidative Stress Promotes Asexual Reproduction and Apogamy in the Red Seaweed Pyropia yezoensis.

    Science.gov (United States)

    Takahashi, Megumu; Mikami, Koji

    2017-01-01

    The marine red seaweed Pyropia yezoensis has a haploid-diploid life cycle wherein two heteromorphic generations, a haploid gametophyte and a diploid sporophyte, are reciprocally generated from conchospores and carpospores, respectively. When we treated gametophytic blades of P. yezoensis with H2O2, discharge of asexual monospores was accelerated, resulting in increased numbers of gametophytic clones. Production of sporophytes without fertilization of male and female gametes was also observed. These findings indicate that oxidative stress can induce vegetative cells to develop into monospores that produce gametophytes asexually and can sometimes prompt carpospores to develop into sporophytes. The discovery of oxidative stress-triggered asexual reproduction and -apogamy will stimulate progress in studies of life-cycle regulation in P. yezoensis.

  17. [Morphofunctional organization of reserve stem cells providing for asexual and sexual reproduction of invertebrates].

    Science.gov (United States)

    Isaeva, V V; Akhmadieva, A V; Aleksandriova, Ia N; Shukaliuk, A I

    2009-01-01

    Published and original data indicating evolutionary conservation of the morphofunctional organization of reserve stem cells providing for asexual and sexual reproduction of invertebrates are reviewed. Stem cells were studied in representatives of five animal types: archeocytes in sponge Oscarella malakhovi (Porifera), large interstitial cells in colonial hydroid Obelia longissima (Cnidaria), neoblasts in an asexual race of planarian Girardia tigrina (Platyhelmintes), stem cells in colonial rhizocephalans Peltogasterella gracilis, Polyascus polygenea, and Thylacoplethus isaevae (Arthropoda), and colonial ascidian Botryllus tuberatus (Chordata). Stem cells in animals of such diverse taxa feature the presence of germinal granules, are positive for proliferating cell nuclear antigen, demonstrate alkaline phosphatase activity (at marker of embryonic stem cells and primary germ cells in vertebrates), and rhizocephalan stem cells express the vasa-like gene (such genes are expressed in germline cells of different metazoans). The self-renewing pool of stem cells is the cellular basis of the reproductive strategy including sexual and asexual reproduction.

  18. Induction of cell death on Plasmodium falciparum asexual blood stages by Solanum nudum steroids

    DEFF Research Database (Denmark)

    López, Mary Luz; Vommaro, Rossiane; Zalis, Mariano

    2010-01-01

    . The Mitochondria presented no morphological alterations and the nuclei showed no abnormal chromatin condensation. By the use of S. nudum compounds, cell death in P. falciparum was evident by a decrease in mitochondrial membrane potential, DNA fragmentation and cytoplasmic acidification. The asexual blood stages......-87 μM. However, their mode of action is unknown. Steroids regulate important cellular functions including cell growth, differentiation and death. Thus, the aim of this work was to determine the effects of S. nudum compounds on P. falciparum asexual blood stages and their association with cell death. We...... of P. falciparum showed some apoptotic-like and autophagic-like cell death characteristics induced by SNs treatment....

  19. Genetic tests of ancient asexuality in Root Knot Nematodes reveal recent hybrid origins

    Directory of Open Access Journals (Sweden)

    Lunt David H

    2008-07-01

    Full Text Available Abstract Background The existence of "ancient asexuals", taxa that have persisted for long periods of evolutionary history without sexual recombination, is both controversial and important for our understanding of the evolution and maintenance of sexual reproduction. A lack of sex has consequences not only for the ecology of the asexual organism but also for its genome. Several genetic signatures are predicted from long-term asexual (apomictic reproduction including (i large "allelic" sequence divergence (ii lack of phylogenetic clustering of "alleles" within morphological species and (iii decay and loss of genes specific to meiosis and sexual reproduction. These genetic signatures can be hard to assess since it is difficult to demonstrate the allelic nature of very divergent sequences, divergence levels may be complicated by processes such as inter-specific hybridization, and genes may have secondary roles unrelated to sexual reproduction. Apomictic species of Meloidogyne root knot nematodes have been suggested previously to be ancient asexuals. Their relatives reproduce by meiotic parthenogenesis or facultative sexuality, which in combination with the abundance of nematode genomic sequence data, makes them a powerful system in which to study the consequences of reproductive mode on genomic divergence. Results Here, sequences from nuclear protein-coding genes are used to demonstrate that the first two predictions of ancient asexuality are found within the apomictic root knot nematodes. Alleles are more divergent in the apomictic taxa than in those species exhibiting recombination and do not group phylogenetically according to recognized species. In contrast some nuclear alleles, and mtDNA, are almost identical across species. Sequencing of Major Sperm Protein, a gamete-specific gene, from both meiotic and ameiotic species reveals no increase in evolutionary rate nor change in substitution pattern in the apomictic taxa, indicating that the locus

  20. Different Responses of Sexual and Asexual Reproduction of Arundinella hirta to Flooding

    Institute of Scientific and Technical Information of China (English)

    Zeng Bo; Fu Tianfei; Ulrich Schurr; Arnd J.Kuhn

    2006-01-01

    The sexual and asexual reproductive features of the graminoid species Arundinella hirta growing at riversides of the Jialing River were analyzed.It was found that the total seed mass,seed number per plant,and sexual reproductive allocation of A.hirta decreased with decreasing bank elevation,and plants growing at the lowest elevations of banks subjected to intense flooding did not show sexual reproduction.The total plant biomass and the number of ramifications per plant increased with flooding intensity,which implies that,contrary to sexual reproduction,asexual reproduction of A.hirta was enhanced by flooding.

  1. Is biomass a reliable estimate of plant fitness?1

    Science.gov (United States)

    Younginger, Brett S.; Sirová, Dagmara; Cruzan, Mitchell B.; Ballhorn, Daniel J.

    2017-01-01

    The measurement of fitness is critical to biological research. Although the determination of fitness for some organisms may be relatively straightforward under controlled conditions, it is often a difficult or nearly impossible task in nature. Plants are no exception. The potential for long-distance pollen dispersal, likelihood of multiple reproductive events per inflorescence, varying degrees of reproductive growth in perennials, and asexual reproduction all confound accurate fitness measurements. For these reasons, biomass is frequently used as a proxy for plant fitness. However, the suitability of indirect fitness measurements such as plant size is rarely evaluated. This review outlines the important associations between plant performance, fecundity, and fitness. We make a case for the reliability of biomass as an estimate of fitness when comparing conspecifics of the same age class. We reviewed 170 studies on plant fitness and discuss the metrics commonly employed for fitness estimations. We find that biomass or growth rate are frequently used and often positively associated with fecundity, which in turn suggests greater overall fitness. Our results support the utility of biomass as an appropriate surrogate for fitness under many circumstances, and suggest that additional fitness measures should be reported along with biomass or growth rate whenever possible. PMID:28224055

  2. Fitness cost

    DEFF Research Database (Denmark)

    Nielsen, Karen L.; Pedersen, Thomas M.; Udekwu, Klas I.

    2012-01-01

    of each isolate was determined in a growth competition assay with a reference isolate. Significant fitness costs of 215 were determined for the MRSA isolates studied. There was a significant negative correlation between number of antibiotic resistances and relative fitness. Multiple regression analysis...... to that seen in Denmark. We propose a significant fitness cost of resistance as the main bacteriological explanation for the disappearance of the multiresistant complex 83A MRSA in Denmark following a reduction in antibiotic usage.......Denmark and several other countries experienced the first epidemic of methicillin-resistant Staphylococcus aureus (MRSA) during the period 196575, which was caused by multiresistant isolates of phage complex 83A. In Denmark these MRSA isolates disappeared almost completely, being replaced by other...

  3. "And Now I'm Just Different, but There's Nothing Actually Wrong With Me": Asexual Marginalization and Resistance.

    Science.gov (United States)

    Gupta, Kristina

    2017-01-01

    This article explores the relationship between contemporary asexual lives and compulsory sexuality, or the privileging of sexuality and the marginalizing of nonsexuality. Drawing on 30 in-depth interviews, I identify four ways the asexually identified individuals in this study saw themselves as affected by compulsory sexuality: pathologization, isolation, unwanted sex and relationship conflict, and the denial of epistemic authority. I also identify five ways these asexually identified individuals disrupted compulsory sexuality: adopting a language of difference and a capacity to describe asexuality; deemphasizing the importance of sexuality in human life; developing new types of nonsexual relationships; constituting asexuality as a sexual orientation or identity; and engaging in community building and outreach. I argue that some of these practices offer only a limited disruption of compulsory sexuality, but some of these practices pose a radical challenge to sexual norms by calling into question the widespread assumption that sexuality is a necessary part of human flourishing.

  4. Fitness Club

    CERN Multimedia

    Fitness Club

    2012-01-01

    Get in Shape for Summer with the CERN Fitness Club Saturday 23 June 2012 from 14:30 to 16.30 (doors open at 14.00) Germana’s Fitness Workshop. Build strength and stamina, sculpt and tone your body and get your heart pumping with Germana’s workout mixture of Cardio Attack, Power Pump, Power Step, Cardio Combat and Cross-Training. Where: 216 (Pump room – equipped with changing rooms and showers). What to wear: comfortable clothes and indoor sports shoes + bring a drink! How much: 15 chf Sign up here: https://espace.cern.ch/club-fitness/Lists/Test_Subscription/NewForm.aspx? Join the Party and dance yourself into shape at Marco + Marials Zumba Masterclass. Saturday 30 June 2012 from 15:00 to 16:30 Marco + Mariel’s Zumba Masterclass Where: 216 (Pump room – equipped with changing rooms and showers). What to wear: comfortable clothes and indoor sports shoes + bring a drink! How much: 25 chf Sign up here: https://espace.cern.ch/club-fitness/Lists/Zumba%20...

  5. Fitness Club

    CERN Multimedia

    Fitness Club

    2012-01-01

      The CERN Fitness Club is pleased to announce its new early morning class which will be taking place on: Tuesdays from 24th April 07:30 to 08:15 216 (Pump Hall, close to entrance C) – Facilities include changing rooms and showers. The Classes: The early morning classes will focus on workouts which will help you build not only strength and stamina, but will also improve your balance, and coordination. Our qualified instructor Germana will accompany you throughout the workout  to ensure you stay motivated so you achieve the best results. Sign up and discover the best way to start your working day full of energy! How to subscribe? We invite you along to a FREE trial session, if you enjoy the activity, please sign up via our website: https://espace.cern.ch/club-fitness/Activities/SUBSCRIBE.aspx. * * * * * * * * Saturday 28th April Get in shape for the summer at our fitness workshop and zumba dance party: Fitness workshop with Germana 13:00 to 14:30 - 216 (Pump Hall) Price...

  6. Fitness club

    CERN Multimedia

    Fitness club

    2013-01-01

      Nordic Walking Classes Come join the Nordic walking classes and outings offered by the CERN Fitness Club starting September 2013. Our licensed instructor Christine offers classes for people who’ve never tried Nordic Walking and who would like to learn the technique, and outings for people who have completed the classes and enjoy going out as a group. Course 1: Tuesdays 12:30 - 13:30 24 September, 1 October, 8 October, 15 October Course 2: Tuesdays 12:30 - 13:30 5 November, 12 November, 19 November, 26 November Outings will take place on Thursdays (12:30 to 13:30) from 12 September 2013. We meet at the CERN Club Barracks car park (close to Entrance A) 10 minutes before departure. Prices: 50 CHF for 4 classes, including the 10 CHF Club membership. Payments made directly to instructor. Renting Poles: Poles can be rented from Christine at 5 CHF / hour. Subscription: Please subscribe at: http://cern.ch/club-fitness Looking forward to seeing you among us! Fitness Club FitnessClub@c...

  7. Biochemical characterization of a novel cold-adapted GH39 β-agarase, AgaJ9, from an agar-degrading marine bacterium Gayadomonas joobiniege G7.

    Science.gov (United States)

    Jung, Subin; Lee, Chang-Ro; Chi, Won-Jae; Bae, Chang-Hwan; Hong, Soon-Kwang

    2017-03-01

    Gayadomonas joobiniege G7 is an agar-degrading marine bacterium belonging to a novel genus. Genomic sequencing of G. joobiniege revealed that AgaJ9 (formerly YjdB) belonging to the glycoside hydrolase (GH) 39 family. It showed the highest similarity (47% identity) to a putative β-agarase from Catenovulum agarivorans DS-2, an agar-degrading marine bacterium sharing the highest similarity in the nucleotide sequence of 16s rRNA gene with G. joobiniege G7. The agaJ9 gene encodes a protein (134 kDa) of 1205 amino acids, including a 23-amino acid signal peptide. The agarase activity of purified AgaJ9 was confirmed by zymogram analysis. The optimum pH and temperature for AgaJ9 activity were determined as 5 and 25 °C, respectively. Notably, AgaJ9 is a cold-adapted β-agarase retaining more than 80% of its activity even at a temperature of 5 °C. In addition, gel filtration chromatography revealed that AgaJ9 exists as two forms, dimer and monomer. Although the two forms had similar enzymatic properties, their kinetic parameters were different. The K m and V max of dimeric AgaJ9 for agarose was 0.68 mg/ml (5.7 × 10(-6) M) and 17.2 U/mg, respectively, whereas the monomeric form had a K m of 1.43 mg/ml (1.2 × 10(-5) M) and V max of 10.7 U/mg. Thin-layer chromatography and agarose-liquefying analyses revealed that AgaJ9 is an endo-type β-agarase that hydrolyzes agarose into neoagarotetraose and neoagarobiose. This study is the first report of a GH39 β-agarase with a cold-adapted enzymatic feature, a unique attribute, which may be useful for industrial applications.

  8. Cognitive fitness.

    Science.gov (United States)

    Gilkey, Roderick; Kilts, Clint

    2007-11-01

    Recent neuroscientific research shows that the health of your brain isn't, as experts once thought, just the product of childhood experiences and genetics; it reflects your adult choices and experiences as well. Professors Gilkey and Kilts of Emory University's medical and business schools explain how you can strengthen your brain's anatomy, neural networks, and cognitive abilities, and prevent functions such as memory from deteriorating as you age. The brain's alertness is the result of what the authors call cognitive fitness -a state of optimized ability to reason, remember, learn, plan, and adapt. Certain attitudes, lifestyle choices, and exercises enhance cognitive fitness. Mental workouts are the key. Brain-imaging studies indicate that acquiring expertise in areas as diverse as playing a cello, juggling, speaking a foreign language, and driving a taxicab expands your neural systems and makes them more communicative. In other words, you can alter the physical makeup of your brain by learning new skills. The more cognitively fit you are, the better equipped you are to make decisions, solve problems, and deal with stress and change. Cognitive fitness will help you be more open to new ideas and alternative perspectives. It will give you the capacity to change your behavior and realize your goals. You can delay senescence for years and even enjoy a second career. Drawing from the rapidly expanding body of neuroscience research as well as from well-established research in psychology and other mental health fields, the authors have identified four steps you can take to become cognitively fit: understand how experience makes the brain grow, work hard at play, search for patterns, and seek novelty and innovation. Together these steps capture some of the key opportunities for maintaining an engaged, creative brain.

  9. "Asexual propagation of a virulent clone complex in human and feline outbreak of sporotrichosis"

    NARCIS (Netherlands)

    Teixeira, Marcus de Melo; Rodrigues, Anderson Messias; Tsui, Clement K M; de Almeida, Luiz Gonzaga Paulo; Van Diepeningen, Anne D; Gerrits van den Ende, Bert; Fernandes, Geisa Ferreira; Kano, Rui; Hamelin, Richard C; Lopes-Bezerra, Leila Maria; Ribeiro Vasconcelos, Ana Tereza; de Hoog, Sybren; de Camargo, Zoilo Pires; Felipe, Maria Sueli Soares

    2014-01-01

    Sporotrichosis is one of the most frequent subcutaneous fungal infections to human and animals caused by members of the plant-associated, dimorphic genus Sporothrix. Three of the four medically important Sporothrix species found in Brazil have been considered asexual, as no sexual stage has ever bee

  10. Vegetative Compatibility and Asexual Recombination in Magnaporthe grisea from Jiangsu Province, China

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-li; ZHANG Zheng-guang; ZHENG Xiao-bo

    2003-01-01

    Vegetative compatibility among isolates of different races in Magnaporthe grisea collectedfrom Jiangsu Province and asexual recombination among compatible isolates by anastomosis were tested.Twenty isolates involving seven races from diseased rice plants were paired on polished rice rose bengal mediumand incubated at 25℃ in darkness for 18 days. Among 173 pairings tested, solid hyphai fusion lines formed byanastomosis between 124 pairings, indicated that these isolates were vegetative compatible with each other.The result showed that most M. grisea isolates were vegetative compatible. Furthermore, 17 vegetative com-patible pairings between monoconidial isolates with MBCsIPTr marker and isolates with MBCrIPTs markerwere selected to detect the asexual recombination between the compatible isolates of different races. The asexu-al recombinants with MBCrIPTr marker were detected in single hyphal fragment progenies in thirteen of theseventeen pairings. The percentage of recombinants was about 0.6 - 11.3%. Results showed that vegetative com-patibility was prevailing among isolates of M. grisea in Jiangsu Province in vitro. These results also suggested thatasexual recombination may be an important mechanism for M. grisea to maintain genetic diversity in nature.

  11. Comparative studies of jaw morphology and ontogeny in two species of asexually reproducing Dorvilleidae (Annelida)

    DEFF Research Database (Denmark)

    Macnaughton, Martin Oliver; Eibye-Jacobsen, Danny; Worsaae, Katrine

    2011-01-01

    The jaw ontogeny of Dorvillea albomaculata and D. bermudensis was studied in cultured specimens, reproducing asexually by transverse fission. Mandibular growth was found to occur by lateral apposition. Maxillary development exhibited a gradual growth pattern, as opposed to the maxillary moults fo...

  12. Ontology for the asexual development and anatomy of the colonial chordate Botryllus schlosseri.

    Directory of Open Access Journals (Sweden)

    Lucia Manni

    Full Text Available Ontologies provide an important resource to integrate information. For developmental biology and comparative anatomy studies, ontologies of a species are used to formalize and annotate data that are related to anatomical structures, their lineage and timing of development. Here, we have constructed the first ontology for anatomy and asexual development (blastogenesis of a bilaterian, the colonial tunicate Botryllus schlosseri. Tunicates, like Botryllus schlosseri, are non-vertebrates and the only chordate taxon species that reproduce both sexually and asexually. Their tadpole larval stage possesses structures characteristic of all chordates, i.e. a notochord, a dorsal neural tube, and gill slits. Larvae settle and metamorphose into individuals that are either solitary or colonial. The latter reproduce both sexually and asexually and these two reproductive modes lead to essentially the same adult body plan. The Botryllus schlosseri Ontology of Development and Anatomy (BODA will facilitate the comparison between both types of development. BODA uses the rules defined by the Open Biomedical Ontologies Foundry. It is based on studies that investigate the anatomy, blastogenesis and regeneration of this organism. BODA features allow the users to easily search and identify anatomical structures in the colony, to define the developmental stage, and to follow the morphogenetic events of a tissue and/or organ of interest throughout asexual development. We invite the scientific community to use this resource as a reference for the anatomy and developmental ontology of B. schlosseri and encourage recommendations for updates and improvements.

  13. Potato (Solanum tuberosum) greenhouse tuber production as an assay for asexual reproduction effects from herbicides

    Science.gov (United States)

    The present study determined whether young potato plants can be used as an assay to indicate potential effects of pesticides on asexual reproduction. Solanum tuberosum (Russet Burbank) plants were grown from seed pieces in a mineral soil in pots under greenhouse conditions. Plant...

  14. Spatial and temporal escape from fungal parasitism in natural communities of anciently asexual bdelloid rotifers.

    Science.gov (United States)

    Wilson, Christopher G; Sherman, Paul W

    2013-08-22

    Sexual reproduction is costly, but it is nearly ubiquitous among plants and animals, whereas obligately asexual taxa are rare and almost always short-lived. The Red Queen hypothesis proposes that sex overcomes its costs by enabling organisms to keep pace with coevolving parasites and pathogens. If so, the few cases of stable long-term asexuality ought to be found in groups whose coevolutionary interactions with parasites are unusually weak. In theory, antagonistic coevolution will be attenuated if hosts disperse among patches within a metapopulation separately from parasites and more rapidly. We examined whether these conditions are met in natural communities of bdelloid rotifers, one of the longest-lived asexual lineages. At any life stage, these microscopic invertebrates can tolerate the complete desiccation of their ephemeral freshwater habitats, surviving as dormant propagules that are readily carried by the wind. In our field experiments, desiccation and wind transport enabled bdelloids to disperse independently of multiple fungal parasites, in both time and space. Surveys of bdelloid communities in unmanipulated moss patches confirmed that fungal parasitism was negatively correlated with extended drought and increasing height (exposure to wind). Bdelloid ecology therefore matches a key condition of models in which asexuals persist through spatio-temporal decoupling from coevolving enemies.

  15. Detection of Gene Flow from Sexual to Asexual Lineages in Thrips tabaci (Thysanoptera: Thripidae).

    Science.gov (United States)

    Li, Xiao-Wei; Wang, Ping; Fail, Jozsef; Shelton, Anthony M

    2015-01-01

    Populations of Thrips tabaci are known to have two sympatric but genetically isolated reproductive modes, arrhenotoky (sexual reproduction) and thelytoky (asexual reproduction). Herein, we report behavioral, ecological and genetic studies to determine whether there is gene flow between arrhenotokous and thelytokous T. tabaci. We did not detect significant preference by arrhenotokous males to mate with females of a particular reproductive mode, nor did we detect significant behavioral differences between arrhenotokous males mated with arrhenotokous or thelytokous females in their pre-copulation, copulation duration and mating frequency. Productive gene transfer resulting from the mating between the two modes was experimentally confirmed. Gene transfer from arrhenotokous T. tabaci to thelytokous T. tabaci was further validated by confirmation of the passage of the arrhenotokous male-originated nuclear gene (histone H3 gene) allele to the F2 generation. These behavioral, ecological and genetic studies confirmed gene transfer from the sexual arrhenotokous mode to the asexual thelytokous mode of T. tabaci in the laboratory. These results demonstrate that asexual T. tabaci populations may acquire genetic variability from sexual populations, which could offset the long-term disadvantage of asexual reproduction.

  16. Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger

    NARCIS (Netherlands)

    Wadman, Mayken W; de Vries, Ronald P; Kalkhove, Stefanie I C; Veldink, Gerrit A; Vliegenthart, Johannes F G

    2009-01-01

    BACKGROUND: Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction 1. An example of such genes are the dio

  17. Potato (Solanum tuberosum) greenhouse tuber production as an assay for asexual reproduction effects from herbicides

    Science.gov (United States)

    The present study determined whether young potato plants can be used as an assay to indicate potential effects of pesticides on asexual reproduction. Solanum tuberosum (Russet Burbank) plants were grown from seed pieces in a mineral soil in pots under greenhouse conditions. Plant...

  18. Sexual vs. asexual reproduction in an ecosystem engineer: the massive coral Montastraea annularis.

    Science.gov (United States)

    Foster, Nicola L; Baums, Iliana B; Mumby, Peter J

    2007-03-01

    1. Long-lived sedentary organisms with a massive morphology are often assumed to utilize a storage effect whereby the persistence of a small group of adults can maintain the population when sexual recruitment fails. However, employing storage effects could prove catastrophic if, under changing climatic conditions, the time period between favourable conditions becomes so prolonged that the population cannot be sustained solely be sexual recruitment. When a species has multiple reproductive options, a rapidly changing environment may favour alternative asexual means of propagation. 2. Here, we revisit the importance of asexual dispersal in a massive coral subject to severe climate-induced disturbance. Montastraea annularis is a major framework-builder of Caribbean coral reefs but its survival is threatened by the increasing cover of macroalgae that prevents settlement of coral larvae. 3. To estimate levels of asexual recruitment within populations of M. annularis, samples from three sites in Honduras were genotyped using four, polymorphic microsatellite loci. 4. A total of 114 unique genets were identified with 8% consisting of two or more colonies and an exceptionally large genet at the third site comprising 14 colonies. 5. At least 70% of multicolony genets observed were formed by physical breakage, consistent with storm damage. 6. Our results reveal that long-lived massive corals can propagate using asexual methods even though sexual strategies predominate.

  19. Detection of Gene Flow from Sexual to Asexual Lineages in Thrips tabaci (Thysanoptera: Thripidae.

    Directory of Open Access Journals (Sweden)

    Xiao-Wei Li

    Full Text Available Populations of Thrips tabaci are known to have two sympatric but genetically isolated reproductive modes, arrhenotoky (sexual reproduction and thelytoky (asexual reproduction. Herein, we report behavioral, ecological and genetic studies to determine whether there is gene flow between arrhenotokous and thelytokous T. tabaci. We did not detect significant preference by arrhenotokous males to mate with females of a particular reproductive mode, nor did we detect significant behavioral differences between arrhenotokous males mated with arrhenotokous or thelytokous females in their pre-copulation, copulation duration and mating frequency. Productive gene transfer resulting from the mating between the two modes was experimentally confirmed. Gene transfer from arrhenotokous T. tabaci to thelytokous T. tabaci was further validated by confirmation of the passage of the arrhenotokous male-originated nuclear gene (histone H3 gene allele to the F2 generation. These behavioral, ecological and genetic studies confirmed gene transfer from the sexual arrhenotokous mode to the asexual thelytokous mode of T. tabaci in the laboratory. These results demonstrate that asexual T. tabaci populations may acquire genetic variability from sexual populations, which could offset the long-term disadvantage of asexual reproduction.

  20. Extensive chromosomal reshuffling drives evolution of virulence in an asexual pathogen

    Science.gov (United States)

    Pathogen populations that undergo regular sexual reproduction are thought to pose a greater risk to plant breeders than pathogens limited to asexual reproduction because they can recombine alleles that contribute to virulence in the face of dynamic environmental conditions. Despite this, many devas...

  1. Evolution of the asexual queen succession system and its underlying mechanisms in termites.

    Science.gov (United States)

    Matsuura, Kenji

    2017-01-01

    One major advantage of sexual reproduction over asexual reproduction is its promotion of genetic variation, although it reduces the genetic contribution to offspring. Queens of social insects double their contribution to the gene pool, while overuse of asexual reproduction may reduce the ability of the colony to adapt to environmental stress because of the loss of genetic diversity. Recent studies have revealed that queens of some termite species can solve this tradeoff by using parthenogenesis to produce the next generation of queens and sexual reproduction to produce other colony members. This reproductive system, known as asexual queen succession (AQS), has been identified in the subterranean termites Reticulitermes speratus, Reticulitermes virginicus and Reticulitermes lucifugus and in the Neotropical higher termites Embiratermes neotenicus and Cavitermes tuberosus The studies presented here have uncovered the unusual modes of reproduction in termites and have aimed to identify their underlying mechanisms. The study of AQS, the mixed use of sexual and asexual reproduction, is of fundamental importance as it may provide a key to solve the evolutionary paradox of sex.

  2. Asexual reproduction in a close relative of Arabidopsis: a genetic investigation of apomixis in Boechera ( Brassicaceae).

    NARCIS (Netherlands)

    Schranz, M.E.; Kantama, L.; Jong, de J.H.S.G.M.; Mitchell-Olds, T.

    2006-01-01

    Understanding apomixis (asexual reproduction through seeds) is of great interest to both plant breeders and evolutionary biologists. The genus Boechera is an excellent system for studying apomixis because of its close relationship to Arabidopsis, the occurrence of apomixis at the diploid level, and

  3. Fitness Club

    CERN Multimedia

    Fitness Club

    2012-01-01

    Nordic Walking Classes Sessions of four classes of one hour each are held on Tuesdays. RDV barracks parking at Entrance A, 10 minutes before class time. Session 1 =  11.09 / 18.09 / 25.09 / 02.10, 18:15 - 19:15 Session 2 = 25.09 / 02.10 / 09.10 / 16.10, 12:30 - 13:30 Session 3 = 23.10 / 30.10 / 06.11 / 13.11, 12:30 - 13:30 Session 4 = 20.11 / 27.11 / 04.12 / 11.12, 12:30 - 13:30 Prices 40 CHF per session + 10 CHF club membership 5 CHF/hour pole rental Check out our schedule and enroll at http://cern.ch/club-fitness   Hope to see you among us!  fitness.club@cern.ch In spring 2012 there was a long-awaited progress in CERN Fitness club. We have officially opened a Powerlifting @ CERN, and the number of members of the new section has been increasing since then reaching 70+ people in less than 4 months. Powerlifting is a strength sport, which is simple as 1-2-3 and efficient. The "1-2-3" are the three basic lifts (bench press...

  4. Coalescence with Background and Balancing Selection in Systems with Bi- and Uniparental Reproduction: Contrasting Partial Asexuality and Selfing.

    Science.gov (United States)

    Agrawal, Aneil F; Hartfield, Matthew

    2016-01-01

    Uniparental reproduction in diploids, via asexual reproduction or selfing, reduces the independence with which separate loci are transmitted across generations. This is expected to increase the extent to which a neutral marker is affected by selection elsewhere in the genome. Such effects have previously been quantified in coalescent models involving selfing. Here we examine the effects of background selection and balancing selection in diploids capable of both sexual and asexual reproduction (i.e., partial asexuality). We find that the effect of background selection on reducing coalescent time (and effective population size) can be orders of magnitude greater when rates of sex are low than when sex is common. This is because asexuality enhances the effects of background selection through both a recombination effect and a segregation effect. We show that there are several reasons that the strength of background selection differs between systems with partial asexuality and those with comparable levels of uniparental reproduction via selfing. Expectations for reductions in Ne via background selection have been verified using stochastic simulations. In contrast to background selection, balancing selection increases the coalescence time for a linked neutral site. With partial asexuality, the effect of balancing selection is somewhat dependent upon the mode of selection (e.g., heterozygote advantage vs. negative frequency-dependent selection) in a manner that does not apply to selfing. This is because the frequency of heterozygotes, which are required for recombination onto alternative genetic backgrounds, is more dependent on the pattern of selection with partial asexuality than with selfing.

  5. The maintenance of sex, clonal dynamics, and host-parasite coevolution in a mixed population of sexual and asexual snails.

    Science.gov (United States)

    Jokela, Jukka; Dybdahl, Mark F; Lively, Curtis M

    2009-07-01

    Sexual populations should be vulnerable to invasion and replacement by ecologically similar asexual females because asexual lineages have higher per capita growth rates. However, as asexual genotypes become common, they may also become disproportionately infected by parasites. The Red Queen hypothesis postulates that high infection rates in the common asexual clones could periodically favor the genetically diverse sexual individuals and promote the short-term coexistence of sexual and asexual populations. Testing this idea requires comparison of competing sexual and asexual lineages that are attacked by natural parasites. To date no such data have been available. Here, we report on long-term dynamics and parasite coevolution in a "mixed" (sexual and asexual) population of snails (Potamopyrgus antipodarum). We found that, within 7-10 years, the most common clones were almost completely replaced by initially rare clones in two different habitats, while sexuals persisted throughout the study period. The common clones, which were initially more resistant to infection, also became more susceptible to infection by sympatric (but not allopatric) parasites over the course of the study. These results are consistent with the Red Queen hypothesis and show that the coevolutionary dynamics predicted by the theory may also favor sexual reproduction in natural populations.

  6. Persistent Copulation in Asexual Female   Potamopyrgus antipodarum: Evidence for Male Control with Size-Based Preferences

    Directory of Open Access Journals (Sweden)

    Amanda E. Nelson

    2011-01-01

    Full Text Available Transitions from sexual to asexual reproduction provide a useful context for investigating the evolutionary loss of nonfunctional traits. It is often assumed that useless behaviors or structures will degrade, but this process is poorly understood. Potamopyrgus antipodarum is an ancestrally sexual New Zealand freshwater snail characterized by numerous independent transitions to asexual all-female lineages. The availability of multiple independently-derived asexual lineages of various time since derivation from sexual ancestors means that the P. antipodarum system is well-suited for the study of trait loss related to mating behavior and copulation. Here, we asked whether mating behavior in asexual female P. antipodarum degrades with increasing asexual lineage age. While copulation frequency did not differ in females from old versus young asexual lineages, post hoc analyses indicated that it was instead positively associated with mean lineage female size. We observed that female P. antipodarum take a passive physical role in copulatory interactions, indicating that female behavior may not be a useful variable for detection of sex-related vestigialization in this system. Instead, males seem to be in proximate control of copulation frequencies, meaning that male mating behavior may be a primary determinant of the expression of mating behavior in asexual female P. antipodarum.

  7. Role of epistasis on the fixation probability of a non-mutator in an adapted asexual population.

    Science.gov (United States)

    James, Ananthu

    2016-10-21

    The mutation rate of a well adapted population is prone to reduction so as to have a lower mutational load. We aim to understand the role of epistatic interactions between the fitness affecting mutations in this process. Using a multitype branching process, the fixation probability of a single non-mutator emerging in a large asexual mutator population is analytically calculated here. The mutator population undergoes deleterious mutations at constant, but at a much higher rate than that of the non-mutator. We find that antagonistic epistasis lowers the chances of mutation rate reduction, while synergistic epistasis enhances it. Below a critical value of epistasis, the fixation probability behaves non-monotonically with variation in the mutation rate of the background population. Moreover, the variation of this critical value of the epistasis parameter with the strength of the mutator is discussed in the appendix. For synergistic epistasis, when selection is varied, the fixation probability reduces overall, with damped oscillations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Cryptic sexual populations account for genetic diversity and ecological success in a widely distributed, asexual fungus-growing ant.

    Science.gov (United States)

    Rabeling, Christian; Gonzales, Omar; Schultz, Ted R; Bacci, Maurício; Garcia, Marcos V B; Verhaagh, Manfred; Ishak, Heather D; Mueller, Ulrich G

    2011-07-26

    Sex and recombination are central processes in life generating genetic diversity. Organisms that rely on asexual propagation risk extinction due to the loss of genetic diversity and the inability to adapt to changing environmental conditions. The fungus-growing ant species Mycocepurus smithii was thought to be obligately asexual because only parthenogenetic populations have been collected from widely separated geographic localities. Nonetheless, M. smithii is ecologically successful, with the most extensive distribution and the highest population densities of any fungus-growing ant. Here we report that M. smithii actually consists of a mosaic of asexual and sexual populations that are nonrandomly distributed geographically. The sexual populations cluster along the Rio Amazonas and the Rio Negro and appear to be the source of independently evolved and widely distributed asexual lineages, or clones. Either apomixis or automixis with central fusion and low recombination rates is inferred to be the cytogenetic mechanism underlying parthenogenesis in M. smithii. Males appear to be entirely absent from asexual populations, but their existence in sexual populations is indicated by the presence of sperm in the reproductive tracts of queens. A phylogenetic analysis of the genus suggests that M. smithii is monophyletic, rendering a hybrid origin of asexuality unlikely. Instead, a mitochondrial phylogeny of sexual and asexual populations suggests multiple independent origins of asexual reproduction, and a divergence-dating analysis indicates that M. smithii evolved 0.5-1.65 million years ago. Understanding the evolutionary origin and maintenance of asexual reproduction in this species contributes to a general understanding of the adaptive significance of sex.

  9. Length of adaptive walk on uncorrelated and correlated fitness landscapes.

    Science.gov (United States)

    Seetharaman, Sarada; Jain, Kavita

    2014-09-01

    We consider the adaptation dynamics of an asexual population that walks uphill on a rugged fitness landscape which is endowed with a large number of local fitness peaks. We work in a parameter regime where only those mutants that are a single mutation away are accessible, as a result of which the population eventually gets trapped at a local fitness maximum and the adaptive walk terminates. We study how the number of adaptive steps taken by the population before reaching a local fitness peak depends on the initial fitness of the population, the extreme value distribution of the beneficial mutations, and correlations among the fitnesses. Assuming that the relative fitness difference between successive steps is small, we analytically calculate the average walk length for both uncorrelated and correlated fitnesses in all extreme value domains for a given initial fitness. We present numerical results for the model where the fitness differences can be large and find that the walk length behavior differs from that in the former model in the Fréchet domain of extreme value theory. We also discuss the relevance of our results to microbial experiments.

  10. Fitness club

    CERN Multimedia

    Fitness club

    2013-01-01

    Nordic Walking Classes New session of 4 classes of 1 hour each will be held on Tuesdays in May 2013. Meet at the CERN barracks parking at Entrance A, 10 minutes before class time. Dates and time: 07.05, 14.05, 21.05 and 28.05, fom  12 h 30 to 13 h 30 Prices: 40 CHF per session + 10 CHF club membership – 5 CHF / hour pole rental Check out our schedule and enroll at http://cern.ch/club-fitness Hope to see you among us! 

  11. Isolation, characterization, and localization of AgaSGNH cDNA: a new SGNH-motif plant hydrolase specific to Agave americana L. leaf epidermis.

    Science.gov (United States)

    Reina, José J; Guerrero, Consuelo; Heredia, Antonio

    2007-01-01

    GDSL and SGNH hydrolases are lipases involved in a wide range of functions, behaving in many cases as bifunctional enzymes. In this work, the isolation and characterization of AgaSGNH, a cDNA encoding a member of the SGNH-hydrolase superfamily from young leaf epidermis of the monocot Agave americana L., is reported. The protein possesses a typical signal peptide at its N-terminus that allows its secretion to the epidermis cell wall, as verified by immunolocalization experiments. In addition, the AgaSGNH sequence contains a His-Leu-Gly-Ala-Glu (HLGAE) motif which is similar to that observed in other plant acyltransferases. Expression levels by northern blot and in situ localization of the corresponding mRNA, as well as the immunolocalization of the protein in Agave young leaves indicate that the protein is specifically present in the epidermal cells. The detailed study performed in different parts of the Agave leaf confirms two aspects: first, the expression of AgaSGNH is limited to the epidermis, and second, the maximum mRNA levels are found in the epidermis of the youngest zones of the leaf which are especially active in cutin biosynthesis. These levels dramatically decrease in the oldest zone of the leaf, where the presence of AgaSGNH mRNA is undetectable, and the biosynthesis of different cuticle components is severely reduced. These data could be compatible with the hypothesis that AgaSGNH could carry out both the hydrolysis and the transfer, from an activated acyl-CoA to a crescent cutin in Agave americana leaves and, therefore, be involved in the still unknown mechanism of plant cutin biosynthesis.

  12. Differential responses of sexual and asexual Artemia to genotoxicity by a reference mutagen: Is the comet assay a reliable predictor of population level responses?

    Science.gov (United States)

    Sukumaran, Sandhya; Grant, Alastair

    2013-05-01

    The impact of chronic genotoxicity to natural populations is always questioned due to their reproductive surplus. We used a comet assay to quantify primary DNA damage after exposure to a reference mutagen ethyl methane sulfonate in two species of crustacean with different reproductive strategies (sexual Artemia franciscana and asexual Artemia parthenogenetica). We then assessed whether this predicted individual performance and population growth rate over three generations. Artemia were exposed to different chronic concentrations (0.78mM, 1.01mM, 1.24mM and 1.48mM) of ethyl methane sulfonate from instar 1 onwards for 3 h, 24 h, 7 days, 14 days and 21 days and percentage tail DNA values were used for comparisons between species. The percentage tail DNA values showed consistently elevated values up to 7 days and showed a reduction from 14 days onwards in A. franciscana. Whilst in A. parthenogenetica such a reduction was evident on 21 days assessment. The values of percentage tail DNA after 21 days were compared with population level fitness parameters, growth, survival, fecundity and population growth rate to know whether primary DNA damage as measured by comet assay is a reliable biomarker. Substantial increase in tail DNA values was associated with substantial reductions in all the fitness parameters in the parental generation of A. franciscana and parental, F1 and F2 generations of A. parthenogenetica. So comet results were more predictive in asexual species over generations. These results pointed to the importance of predicting biomarker responses from multigenerational consequences considering life history traits and reproductive strategies in ecological risk assessments.

  13. The conservation of redundancy in genetic systems: effects of sexual and asexual reproduction

    Indian Academy of Sciences (India)

    J A Morris; R D Morris

    2003-12-01

    The relationship between probability of survival and the number of deleterious mutations in the genome is investigated using three different models of highly redundant systems that interact with a threatening environment. Model one is a system that counters a potentially lethal infection; it has multiple identical components that act in sequence and in parallel. Model two has many different overlapping components that provide threefold coverage of a large number of vital functions. The third model is based on statistical decision theory: an ideal detector, following an optimum decision strategy, makes crucial decisions in an uncertain world. The probability of a fatal error is reduced by a redundant sampling system, but the chance of error rises as the system is impaired by deleterious mutations. In all three cases the survival profile shows a synergistic pattern in that the probability of survival falls slowly and then more rapidly. This is different than the multiplicative or independent survival profile that is often used in mathematical models. It is suggested that a synergistic profile is a property of redundant systems. Model one is then used to study the conservation of redundancy during sexual and asexual reproduction. A unicellular haploid organism reproducing asexually retains redundancy when the mutation rate is very low (0.001 per cell division), but tends to lose high levels of redundancy if the mutation rate is increased (0.01 to 0.1 per cell division). If a similar unicellular haploid organism has a sexual phase then redundancy is retained for mutation rates between 0.001 and 0.1 per cell division. The sexual organism outgrows the asexual organism when the above mutation rates apply. If they compete for finite resources the asexual organism will be extinguished. Variants of the sexual organism with increased redundancy will outgrow those with lower levels of redundancy and the sexual process facilitates the evolution of more complex forms. There is a

  14. The conservation of redundancy in genetic systems: effects of sexual and asexual reproduction.

    Science.gov (United States)

    Morris, J A; Morris, R D

    2003-12-01

    The relationship between probability of survival and the number of deleterious mutations in the genome is investigated using three different models of highly redundant systems that interact with a threatening environment. Model one is a system that counters a potentially lethal infection; it has multiple identical components that act in sequence and in parallel. Model two has many different overlapping components that provide threefold coverage of a large number of vital functions. The third model is based on statistical decision theory: an ideal detector, following an optimum decision strategy, makes crucial decisions in an uncertain world. The probability of a fatal error is reduced by a redundant sampling system, but the chance of error rises as the system is impaired by deleterious mutations. In all three cases the survival profile shows a synergistic pattern in that the probability of survival falls slowly and then more rapidly. This is different than the multiplicative or independent survival profile that is often used in mathematical models. It is suggested that a synergistic profile is a property of redundant systems. Model one is then used to study the conservation of redundancy during sexual and asexual reproduction. A unicellular haploid organism reproducing asexually retains redundancy when the mutation rate is very low (0.001 per cell division), but tends to lose high levels of redundancy if the mutation rate is increased (0.01 to 0.1 per cell division). If a similar unicellular haploid organism has a sexual phase then redundancy is retained for mutation rates between 0.001 and 0.1 per cell division. The sexual organism outgrows the asexual organism when the above mutation rates apply. If they compete for finite resources the asexual organism will be extinguished. Variants of the sexual organism with increased redundancy will outgrow those with lower levels of redundancy and the sexual process facilitates the evolution of more complex forms. There is a

  15. A multi-stage malaria vaccine candidate targeting both transmission and asexual parasite life-cycle stages

    DEFF Research Database (Denmark)

    Theisen, Michael; Roeffen, Will; Singh, Susheel K

    2014-01-01

    Effective control and eventual eradication of malaria drives the imperative need for clinical development of a malaria vaccine. Asexual parasite forms are responsible for clinical disease and death while apathogenic gametocytes are responsible for transmission from man to mosquito. Vaccines...

  16. Fitness seascapes and adaptive evolution of the influenza virus

    Science.gov (United States)

    Lassig, Michael

    2014-03-01

    The seasonal human influenza A virus undergoes rapid genome evolution. This process is triggered by interactions with the host immune system and produces significant year-to-year sequence turnover in the population of circulating viral strains. We develop a dynamical fitness model that predicts the evolution of the viral population from one year to the next. Two factors are shown to determine the fitness of a viral strain: adaptive changes, which are under positive selection, and deleterious mutations, which affect conserved viral functions such as protein stability. Combined with the influenza strain tree, this fitness model maps the adaptive history of influenza A. We discuss the implications of our results for the statistical theory of adaptive evolution in asexual populations. Based on this and related systems, we touch upon the fundamental question of when evolution can be predicted. Joint work with Marta Luksza, Columbia University.

  17. Using a meiosis detection toolkit to investigate ancient asexual "scandals" and the evolution of sex.

    Science.gov (United States)

    Schurko, Andrew M; Logsdon, John M

    2008-06-01

    Sexual reproduction is the dominant reproductive mode in eukaryotes but, in many taxa, it has never been observed. Molecular methods that detect evidence of sex are largely based on the genetic consequences of sexual reproduction. Here we describe a powerful new approach to directly search genomes for genes that function in meiosis. We describe a "meiosis detection toolkit", a set of meiotic genes that represent the best markers for the presence of meiosis. These genes are widely present in eukaryotes, function only in meiosis and can be isolated by degenerate PCR. The presence of most, or all, of these genes in a genome would suggest they have been maintained for meiosis and, implicitly, sexual reproduction. In contrast, their absence would be consistent with the loss of meiosis and asexuality. This approach will help to understand both meiotic gene evolution and the capacity for meiosis and sex in putative obligate asexuals.

  18. Evolution of Population with Sexual and Asexual Reproduction in Changing Environment

    Science.gov (United States)

    He, Mingfeng; Yu, Changliang; Ruan, Hongbo; Yao, Lei

    Using a lattice model based on Monte Carlo simulations, we study the role of the reproduction pattern on the fate of an evolving population. Each individual is under the selection pressure from the environment and random mutations. The habitat ("climate") is changing periodically. Evolutions of populations following two reproduction patterns are compared, asexual and sexual. We show, via Monte Carlo simulations, that sexual reproduction by keeping more diversified populations gives them better chances to adapt themselves to the changing environment. However, in order to obtain a greater chance to mate, the birth rate should be high. In the case of low birth rate and high mutation probability there is a preference for the asexual reproduction.

  19. Profiling the repertoire of phenotypes influenced by environmental cues that occur during asexual reproduction.

    Science.gov (United States)

    Dombrovsky, Aviv; Arthaud, Laury; Ledger, Terence N; Tares, Sophie; Robichon, Alain

    2009-11-01

    The aphid Acyrthosiphon pisum population is composed of different morphs, such as winged and wingless parthenogens, males, and sexual females. The combined effect of reduced photoperiodicity and cold in fall triggers the apparition of sexual morphs. In contrast they reproduce asexually in spring and summer. In our current study, we provide evidence that clonal individuals display phenotypic variability within asexual morph categories. We describe that clones sharing the same morphological features, which arose from the same founder mother, constitute a repertoire of variants with distinct behavioral and physiological traits. Our results suggest that the prevailing environmental conditions influence the recruitment of adaptive phenotypes from a cohort of clonal individuals exhibiting considerable molecular diversity. However, we observed that the variability might be reduced or enhanced by external factors, but is never abolished in accordance with a model of stochastically produced phenotypes. This overall mechanism allows the renewal of colonies from a few adapted individuals that survive drastic episodic changes in a fluctuating environment.

  20. Population genomics of sexual and asexual lineages in fissiparous ribbon worms (Lineus, Nemertea): hybridization, polyploidy and the Meselson effect.

    Science.gov (United States)

    Ament-Velásquez, S L; Figuet, E; Ballenghien, M; Zattara, E E; Norenburg, J L; Fernández-Álvarez, F A; Bierne, J; Bierne, N; Galtier, N

    2016-07-01

    Comparative population genetics in asexual vs. sexual species offers the opportunity to investigate the impact of asexuality on genome evolution. Here, we analyse coding sequence polymorphism and divergence patterns in the fascinating Lineus ribbon worms, a group of marine, carnivorous nemerteans with unusual regeneration abilities, and in which asexual reproduction by fissiparity is documented. The population genomics of the fissiparous L. pseudolacteus is characterized by an extremely high level of heterozygosity and unexpectedly elevated πN /πS ratio, in apparent agreement with theoretical expectations under clonal evolution. Analysis of among-species allele sharing and read-count distribution, however, reveals that L. pseudolacteus is a triploid hybrid between Atlantic populations of L. sanguineus and L. lacteus. We model and quantify the relative impact of hybridity, polyploidy and asexuality on molecular variation patterns in L. pseudolacteus and conclude that (i) the peculiarities of L. pseudolacteus population genomics result in the first place from hybridization and (ii) the accumulation of new mutations through the Meselson effect is more than compensated by processes of heterozygosity erosion, such as gene conversion or gene copy loss. This study illustrates the complexity of the evolutionary processes associated with asexuality and identifies L. pseudolacteus as a promising model to study the first steps of polyploid genome evolution in an asexual context. © 2016 John Wiley & Sons Ltd.

  1. Toward monophyletic generic concepts in Magnaporthales: species with Harpophora asexual states.

    Science.gov (United States)

    Luo, Jing; Walsh, Emily; Zhang, Ning

    2015-01-01

    We investigated the phylogenetic relationships among Magnaporthales fungi with harpophora-like asexual states based on DNA sequences of ITS, MCM7, RPB1 and TEF1 genes. The results indicated that these species are polyphyletic. Based on the four-gene phylogeny, the type species of Harpophora, H. radicicola, belongs to Gaeumannomyces and thus Harpophora is treated as a synonym of Gaeumannomyces. In addition, a monotypic new genus, Falciphora, is established based on F. oryzae, previous referred as Harpophora oryzae.

  2. Monophyletic origin of multiple clonal lineages in an asexual fish (Poecilia formosa).

    Science.gov (United States)

    Stöck, Matthias; Lampert, Kathrin P; Möller, Dirk; Schlupp, Ingo; Schartl, Manfred

    2010-12-01

    Despite the advantage of avoiding the costs of sexual reproduction, asexual vertebrates are very rare and often considered evolutionarily disadvantaged when compared to sexual species. Asexual species, however, may have advantages when colonizing (new) habitats or competing with sexual counterparts. They are also evolutionary older than expected, leaving the question whether asexual vertebrates are not only rare because of their 'inferior' mode of reproduction but also because of other reasons. A paradigmatic model system is the unisexual Amazon molly, Poecilia formosa, that arose by hybridization of the Atlantic molly, Poecilia mexicana, as the maternal ancestor, and the sailfin molly, Poecilia latipinna, as the paternal ancestor. Our extensive crossing experiments failed to resynthesize asexually reproducing (gynogenetic) hybrids confirming results of previous studies. However, by producing diploid eggs, female F(1) -hybrids showed apparent preadaptation to gynogenesis. In a range-wide analysis of mitochondrial sequences, we examined the origin of P. formosa. Our analyses point to very few or even a single origin(s) of its lineage, which is estimated to be approximately 120,000 years old. A monophyletic origin was supported from nuclear microsatellite data. Furthermore, a considerable degree of genetic variation, apparent by high levels of clonal microsatellite diversity, was found. Our molecular phylogenetic evidence and the failure to resynthesize the gynogenetic P. formosa together with the old age of the species indicate that some unisexual vertebrates might be rare not because they suffer the long-term consequences of clonal reproduction but because they are only very rarely formed as a result of complex genetic preconditions necessary to produce viable and fertile clonal genomes and phenotypes ('rare formation hypothesis').

  3. Implication of a Plasmodium falciparum gene in the switch between asexual reproduction and gametocytogenesis.

    Science.gov (United States)

    Gardiner, Donald L; Dixon, Matthew W A; Spielmann, Tobias; Skinner-Adams, Tina S; Hawthorne, Paula L; Ortega, Maria R; Kemp, David J; Trenholme, Katharine R

    2005-04-01

    Gametocytogenesis is fundamental for transmission of the malaria parasite Plasmodium falciparum from the human host to the mosquito vector, yet very little is understood about what triggers the switch between asexual reproduction and gametocytogenesis. Arresting the progression through the sexual cycle would block transmission of this disease. Here we identify a novel gene in P. falciparum that when genetically silenced reduces gametocyte production by a factor of 6, and when complemented up-regulates gametocyte-specific gene transcription.

  4. Characterization of transcriptomes from sexual and asexual lineages of a New Zealand snail (Potamopyrgus antipodarum).

    Science.gov (United States)

    Wilton, Peter R; Sloan, Daniel B; Logsdon, John M; Doddapaneni, Harshavardhan; Neiman, Maurine

    2013-03-01

    Understanding the evolution and maintenance of sexual reproduction is one of the central challenges of evolutionary biology, yet we know very little about how sex influences molecular evolution. The New Zealand freshwater snail Potamopyrgus antipodarum is ideally suited to address this knowledge gap because obligately sexual individuals often coexist with multiple independently derived obligately asexual lineages. This unusual situation allows direct comparisons both between sexual and asexual P. antipodarum and across populations that differ in the relative frequency of sexual individuals. As such, P. antipodarum has received a great deal of attention as a model system for the maintenance of sex in nature and is also used as a model for environmental toxicology and biological invasions. Molecular genetic resources for P. antipodarum will thus be useful to investigators in a variety of biological fields. We used 454 sequencing of cDNA libraries to generate transcriptomes from two sexual and two asexual P. antipodarum lineages. A de novo assembly of 116.7 Mb of sequence reads produced 41 396 contigs, and sequence similarity-based Gene Ontology annotations were obtained for 3740 contigs. We detected 408 315 SNP loci and 7315 microsatellite loci, which together represent the first genome-scale resource available for P. antipodarum. Raw 454 read sequences, contig sequences, annotation data and polymorphism data are publicly available in a searchable online database and for download at http://www.biology.uiowa.edu/neiman/transcriptome.php.

  5. Plant Growth-Promoting Rhizobacteria Stimulate Vegetative Growth and Asexual Reproduction of Kalanchoe daigremontiana

    Directory of Open Access Journals (Sweden)

    Yong-Soon Park

    2015-09-01

    Full Text Available Certain bacterial species associate with plant roots in soil. The plant growth-promoting rhizobacteria (PGPR stimulate plant growth and yield in greenhouse and field. Here, we examined whether application of known bacilli PGPR strains stimulated growth and asexual reproduction in the succulent plant Kalanchoe daigremontiana. Four PGPR strains B. amyloliquefaciens IN937a, B. cereus BS107, B. pumilus INR7, and B. subtilis GB03 were applied to young plantlets by soil-drenching, and plant growth and development was monitored for three months. Aerial growth was significantly stimulated in PGPR-inoculated plants, which was observed as increases in plant height, shoot weight, and stem width. The stimulated growth influenced plant development by increasing the total number of leaves per plant. Treatment with bacilli also increased the total root biomass compared with that of control plants, and led to a 2-fold increase in asexual reproduction and plantlet formation on the leaf. Collectively, our results firstly demonstrate that Bacillus spp. promote vegetative development of K. daigremontiana, and the enhanced growth stimulates asexual reproduction and plantlet formation.

  6. Evidence of parasexual activity in "asexual amoebae" Cochliopodium spp. (Amoebozoa): extensive cellular and nuclear fusion.

    Science.gov (United States)

    Tekle, Yonas I; Anderson, O Roger; Lecky, Ariel F

    2014-09-01

    The majority of microbial eukaryotes have long been considered asexual, though new evidence indicates sex, or sexual-like (parasexual) behaviors that deviate from the usual union of two gametes, among other variant aspects. Over a dozen amoebozoans are implicated to have sexual stages. However, the exact mechanism by which sex occurs in these lineages remains elusive. This is mainly due to the diverse quality and cryptic nature of their life cycle. In this study we present evidence of some previously unreported aspects of the life cycle of an amoeba, Cochliopodium, that undergoes unusual intraspecific interactions using light microscopy and immunocytochemistry. Similar to other amoebozoans, Cochliopodium, is considered asexual with no published reports of sex or parasexuality. We also investigated environmental conditions that govern the observed intraspecific interactions. Both light microscopic and immunocytochemistry evidence demonstrates Cochliopodium undergoes cellular fusion (plasmogamy) and nuclear fusion (karyogamy). Large plasmodia eventually undergo karyogamy and contain large fused, polyploid, nuclei. These are observed to fragment, subsequently, by karyotomy (nuclear fission) and cytoplasmic fission to yield uninucleated amoebae. This process could lead to a non-meiotic, parasexual exchange of chromosomes in Cochliopodium. These findings strongly suggest that Cochliopodium is involved in parasexual activity and should no longer be considered strictly asexual.

  7. Plant Growth-Promoting Rhizobacteria Stimulate Vegetative Growth and Asexual Reproduction of Kalanchoe daigremontiana.

    Science.gov (United States)

    Park, Yong-Soon; Park, Kyungseok; Kloepper, Joseph W; Ryu, Choong-Min

    2015-09-01

    Certain bacterial species associate with plant roots in soil. The plant growth-promoting rhizobacteria (PGPR) stimulate plant growth and yield in greenhouse and field. Here, we examined whether application of known bacilli PGPR strains stimulated growth and asexual reproduction in the succulent plant Kalanchoe daigremontiana. Four PGPR strains B. amyloliquefaciens IN937a, B. cereus BS107, B. pumilus INR7, and B. subtilis GB03 were applied to young plantlets by soil-drenching, and plant growth and development was monitored for three months. Aerial growth was significantly stimulated in PGPR-inoculated plants, which was observed as increases in plant height, shoot weight, and stem width. The stimulated growth influenced plant development by increasing the total number of leaves per plant. Treatment with bacilli also increased the total root biomass compared with that of control plants, and led to a 2-fold increase in asexual reproduction and plantlet formation on the leaf. Collectively, our results firstly demonstrate that Bacillus spp. promote vegetative development of K. daigremontiana, and the enhanced growth stimulates asexual reproduction and plantlet formation.

  8. Observations of asexual reproductive strategies in Antarctic hexactinellid sponges from ROV video records

    Science.gov (United States)

    Teixidó, Núria; Gili, Josep-Maria; Uriz, María-J.; Gutt, Julian; Arntz, Wolf E.

    2006-04-01

    Hexactinellid sponges are one of the structuring taxa of benthic communities on the Weddell Sea shelf (Antarctica). However, little is known about their reproduction patterns (larval development, release, settlement, and recruitment), particularly in relation to sexual and asexual processes in sponge populations. Video stations obtained during several expeditions covering a wide depth range and different areas recorded a high frequency of asexual reproductive strategies (ARS) (bipartition and budding) among hexactinellids. Analysis of seabed video strips between 108 and 256 m depth, representing an area of 1400 m 2, showed that about 28% of these sponges exhibited ARS. The Rossella nuda type dominated most of the video stations and exhibited the highest proportion of budding (35%). This proportion increased with the size class. Size class >20 cm exhibited in all the stations a mean value of 8.3±0.7 (SE) for primary and of 2.5±0.2 (SE) for secondary propagules per sponge, respectively. Results from a shallow station (Stn 059, 117 m depth) showed the highest relative abundance of R. nuda type and budding (>20 cm ˜72%, 10-20 cm ˜60%, 5-10 cm ˜12%, and asexual reproduction in hexactinellid sponges may be more frequent than has been thought before and it may greatly influence the genetic structure of populations.

  9. Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica.

    Directory of Open Access Journals (Sweden)

    Osamu Nishimura

    Full Text Available We established a laboratory clonal strain of freshwater planarian (Dugesia japonica that was derived from a single individual and that continued to undergo autotomous asexual reproduction for more than 20 years, and we performed large-scale genome sequencing and transcriptome analysis on it. Despite the fact that a completely clonal strain of the planarian was used, an unusually large number of mutations were detected. To enable quantitative genetic analysis of such a unique organism, we developed a new model called the Reference Gene Model, and used it to conduct large-scale transcriptome analysis. The results revealed large numbers of mutations not only outside but also inside gene-coding regions. Non-synonymous SNPs were detected in 74% of the genes for which valid ORFs were predicted. Interestingly, the high-mutation genes, such as metabolism- and defense-related genes, were correlated with genes that were previously identified as diverse genes among different planarian species. Although a large number of amino acid substitutions were apparently accumulated during asexual reproduction over this long period of time, the planarian maintained normal body-shape, behaviors, and physiological functions. The results of the present study reveal a unique aspect of asexual reproduction.

  10. Feeding and asexual reproduction of the jellyfish Sarsia gemmifera in response to resource enrichment.

    Science.gov (United States)

    Stibor, Herwig; Tokle, Nils

    2003-04-01

    Jellyfish are ubiquitous predators in marine pelagic environments and can sometimes control their zooplankton prey populations. Recent considerations of the fertilization of entire food webs in coastal areas make it important to investigate the response of jellyfish to resource enrichment. We investigated feeding, assimilation and life history parameters in the hydromedusa species Sarsia gemmifera. S. gemmifera was able to ingest up to 3 micro g carbon per hour, which corresponds to a daily carbon ingestion that exceeds the individual's body weight (carbon). Conversion of ingested carbon into tissue was less than 30%. The assimilated carbon was allocated such that approximately 65% was used for growth and the remainder for asexual reproduction. Carbon from food was allocated to asexually produced offspring within hours. The numerical response of S. gemmifera reached saturation at prey levels of 100 or more copepods per liter. Propagule quality was influenced by maternal effects: higher net production of the mothers in higher food environments resulted in higher carbon content of individual propagules. Starvation resistance of propagules was therefore positively related to food density in the maternal environment. The food concentrations which S. gemmifera normally experiences in the field are much lower than the food levels at which this species had its maximum asexual reproductive output in the laboratory. Therefore, S. gemmifera may potentially benefit from food web perturbations which increase crustacean zooplankton densities.

  11. Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica.

    Science.gov (United States)

    Nishimura, Osamu; Hosoda, Kazutaka; Kawaguchi, Eri; Yazawa, Shigenobu; Hayashi, Tetsutaro; Inoue, Takeshi; Umesono, Yoshihiko; Agata, Kiyokazu

    2015-01-01

    We established a laboratory clonal strain of freshwater planarian (Dugesia japonica) that was derived from a single individual and that continued to undergo autotomous asexual reproduction for more than 20 years, and we performed large-scale genome sequencing and transcriptome analysis on it. Despite the fact that a completely clonal strain of the planarian was used, an unusually large number of mutations were detected. To enable quantitative genetic analysis of such a unique organism, we developed a new model called the Reference Gene Model, and used it to conduct large-scale transcriptome analysis. The results revealed large numbers of mutations not only outside but also inside gene-coding regions. Non-synonymous SNPs were detected in 74% of the genes for which valid ORFs were predicted. Interestingly, the high-mutation genes, such as metabolism- and defense-related genes, were correlated with genes that were previously identified as diverse genes among different planarian species. Although a large number of amino acid substitutions were apparently accumulated during asexual reproduction over this long period of time, the planarian maintained normal body-shape, behaviors, and physiological functions. The results of the present study reveal a unique aspect of asexual reproduction.

  12. The importance of sexual and asexual reproduction in the recent evolution of Allium vineale.

    Science.gov (United States)

    Ceplitis, A

    2001-08-01

    In the weedy plant species Allium vineale (wild garlic), individuals may simultaneously produce sexually and asexually derived offspring, by seed and bulbils, respectively. In this study, genetic and genotypic diversity was determined in samples from 14 European A. vineale populations using nuclear (RAPD) and cytoplasmic (PCR-RFLP of cpDNA) markers to investigate the importance of the different reproductive modes. In the whole sample, 77 nuclear multilocus genotypes and four chloroplast haplotypes (chlorotypes) were found. Populations exhibited a high degree of subdivision for nuclear and cytoplasmic markers as estimated from hierarchical F-statistics; at the same time, identical chlorotypes could be found in populations separated by large distances. Genotypic diversity was significantly lower than expected under free recombination in almost all populations, indicating that recruitment into populations is mostly by asexually produced offspring. Nevertheless, within each chlorotype, the distribution of markers from pairs of nuclear loci was incompatible with a purely clonal structure, suggesting that many multilocus genotypes have originated by sexual recombination rather than by mutation within asexual lineages. It is argued that the weedy habit of A. vineale is likely to have favored bulbil reproduction, whereas sexually generated genotypes may have facilitated local adaptation during the species' expansion across Europe.

  13. Association of cord blood des-acyl ghrelin with birth weight, and placental GHS-R1 receptor expression in SGA, AGA, and LGA newborns.

    Science.gov (United States)

    González-Domínguez, Martha I; Lazo-de-la-Vega-Monroy, Maria-Luisa; Zaina, Silvio; Sabanero, Myrna; Daza-Benítez, Leonel; Malacara, Juan Manuel; Barbosa-Sabanero, Gloria

    2016-07-01

    Although ghrelin in cord blood has been associated to birth weight, its role in fetal and postnatal growth has not been elucidated. The aim of this study was to analyze total ghrelin, acyl ghrelin (AG), and des-acyl ghrelin (DAG) in cord blood of newborns with idiopathic birth weight alterations, and to evaluate protein expression of placental GHS-R1, in order to investigate their correlation with birth weight and placental weight. We performed a cross-sectional comparative study in umbilical cord blood and placentas from healthy mothers of SGA, AGA, and LGA (small, adequate and large for gestational age) term newborns (n = 20 per group). Cord blood total ghrelin, AG, and DAG were measured by ELISA, and placental GHS-R1 expression was evaluated by Western blot. Cord blood DAG was higher in SGA compared to AGA newborns (902.1 ± 109.1 and 597.4 ± 58.2 pg/ml, respectively, p = 0.01) while LGA and AGA showed similar values (627.2 ± 76.4 pg/ml for LGA, p = 0.80). DAG negatively correlated with birthweight (r = -0.31, p = 0.02) and placental weight (r = -0.33, p = 0.02). No differences in AG or total ghrelin were found. GHS-R1 protein in placenta was not differentially expressed among SGA, AGA, and LGA. Our results suggest a role of DAG in intrauterine growth. Further studies are needed in order to elucidate the mechanisms by which DAG participates in fetal growth.

  14. Enzymatic liquefaction of agarose above the sol-gel transition temperature using a thermostable endo-type β-agarase, Aga16B.

    Science.gov (United States)

    Kim, Jung Hyun; Yun, Eun Ju; Seo, Nari; Yu, Sora; Kim, Dong Hyun; Cho, Kyung Mun; An, Hyun Joo; Kim, Jae-Han; Choi, In-Geol; Kim, Kyoung Heon

    2017-02-01

    The main carbohydrate of red macroalgae is agarose, a heterogeneous polysaccharide composed of D-galactose and 3,6-anhydro-L-galactose. When saccharifying agarose by enzymes, the unique physical properties of agarose, namely the sol-gel transition and the near-insolubility of agarose in water, limit the accessibility of agarose to the enzymes. Due to the lower accessibility of agarose to enzymes in the gel state than to the sol state, it is important to prevent the sol-gel transition by performing the enzymatic liquefaction of agarose at a temperature higher than the sol-gel transition temperature of agarose. In this study, a thermostable endo-type β-agarase, Aga16B, originating from Saccharophagus degradans 2-40(T), was characterized and introduced in the liquefaction process. Aga16B was thermostable up to 50 °C and depolymerized agarose mainly into neoagarooligosaccharides with degrees of polymerization 4 and 6. Aga16B was applied to enzymatic liquefaction of agarose at 45 °C, which was above the sol-gel transition temperature of 1 % (w/v) agarose (∼35 °C) when cooling agarose. This is the first systematic demonstration of enzymatic liquefaction of agarose, enabled by determining the sol-gel temperature of agarose under specific conditions and by characterizing the thermostability of an endo-type β-agarase.

  15. Metabolism of medium- and long-chain fatty acids by isolated hepatocytes from small-for-gestational-age (SGA) and appropriate for-gestational-age (AGA) piglets

    Energy Technology Data Exchange (ETDEWEB)

    Odle, J.; Benevenga, N.J.; Crenshaw, T.D. (Univ. of Wisconsin, Madison (United States))

    1990-02-26

    Hepatocytes were isolated from full-term, SGA and AGA piglets at 6 or 48 hours postpartum and were incubated with 1 mM (1-{sup 14}C)-octanoate (C8), -nonanoate (C9) or-oleate (C18:1). The cells oxidized (natom 1-C/(h 10{sup 6} cells)) C9 to Co{sub 2} (12.5) and acid soluble products (28.9) faster than C8 (10.9, 20.6, respectively), and both were oxidized faster than C18:1 (3.9, 9.9) regardless of the piglet age or weight. Oleate accumulated in lipid products 8-fold faster than C8 and C9. No differences between cells from SGA and AGA piglets were detected. Recovery of 1-C in CO{sub 2} was 48% higher in incubations with cells from 48 hours old than from 6 hour old piglets. This increase was attributable to a 70% higher oxygen consumption by 48 hour old cells. Theoretical oxygen consumption rates were computed from the fatty acid flux data and compared to measured oxygen consumption. hepatocytes from SGA and AGA piglets were equally capable of satisfying more that 57% of their energy needs from fatty acid oxidation. The oxygen consumption attributable to C9 metabolism was 30% higher than observed for C8 and C18:1. All fatty acids apparently spared endogenous fuels to a greater degree in 6 hour than in 48 hour piglets.

  16. Greedy adaptive walks on a correlated fitness landscape.

    Science.gov (United States)

    Park, Su-Chan; Neidhart, Johannes; Krug, Joachim

    2016-05-21

    We study adaptation of a haploid asexual population on a fitness landscape defined over binary genotype sequences of length L. We consider greedy adaptive walks in which the population moves to the fittest among all single mutant neighbors of the current genotype until a local fitness maximum is reached. The landscape is of the rough mount Fuji type, which means that the fitness value assigned to a sequence is the sum of a random and a deterministic component. The random components are independent and identically distributed random variables, and the deterministic component varies linearly with the distance to a reference sequence. The deterministic fitness gradient c is a parameter that interpolates between the limits of an uncorrelated random landscape (c=0) and an effectively additive landscape (c→∞). When the random fitness component is chosen from the Gumbel distribution, explicit expressions for the distribution of the number of steps taken by the greedy walk are obtained, and it is shown that the walk length varies non-monotonically with the strength of the fitness gradient when the starting point is sufficiently close to the reference sequence. Asymptotic results for general distributions of the random fitness component are obtained using extreme value theory, and it is found that the walk length attains a non-trivial limit for L→∞, different from its values for c=0 and c=∞, if c is scaled with L in an appropriate combination.

  17. Evolution of reproductive mode variation and host associations in a sexual-asexual complex of aphid parasitoids

    Directory of Open Access Journals (Sweden)

    Sandrock Christoph

    2011-12-01

    Full Text Available Abstract Background The Lysiphlebus fabarum group is a taxonomically poorly resolved complex of aphid parasitoids, presently split into three described species that comprise sexual (arrhenotokous and asexual (thelytokous lineages of unknown relationship. Specifically, it is unclear how asexuals evolved from sexuals in this system, to what extent reproductive modes are still connected by genetic exchange, how much the complex is structured by geography or by host-associated differentiation, and whether species designations are valid. Using a combination of population genetic and phylogenetic approaches, we addressed these issues in a comprehensive sample of parasitoid wasps from across Europe. Results Asexual reproduction predominated in parasitoids of the L. fabarum group, with asexual populations exhibiting high genotypic diversity. Sexual populations were only common in southern France; elsewhere sexual reproduction was restricted to specific aphid hosts. Although reproductive modes were aggregated on the mitochondrial genealogy and significantly differentiated at nuclear microsatellite loci, there was clear evidence for genetic exchange, especially on hosts attacked by sexual and asexual parasitoids. The microsatellite data further revealed that parasitoids collected from certain host aphids were significantly differentiated, yet the mitochondrial sequence variation across the entire L. fabarum group did not exceed 1.32% and exhibited a very shallow topology. Morphological characters used for delineation of described species were found to be phylogenetically non-conservative. Conclusions Our results suggest that the sexual-asexual L. fabarum group represents a young complex of lineages with incomplete isolation between reproductive modes. We propose three mechanisms of genetic exchange that may jointly explain the high genotypic diversity observed in asexual parasitoids: (i the formation of new asexual lineages via 'contagious parthenogenesis

  18. Gene flow between sexual and facultatively asexual lineages of an aphid species and the maintenance of reproductive mode variation.

    Science.gov (United States)

    Halkett, F; Plantegenest, M; Bonhomme, J; Simon, J-C

    2008-06-01

    Many organisms considered as strictly clonal may in fact experience some rare events of sexual reproduction with their sexual relatives. However, the rate of sexual-asexual gene flow has rarely been assessed mainly because its evaluation is difficult to achieve in the field. In the cyclically parthenogenetic aphid Rhopalosiphum padi, two main sets of lineages, differing in their investment in sexual reproduction and in their genetic attributes, co-exist even at a very fine scale: the 'sexual' lineages which have a full commitment to the sexual reproduction, and the 'facultatively asexual' lineages, which allocate investment in the sexual and parthenogenetic reproduction. This system offers a unique opportunity to tackle the genetic interactions between two contrasting reproductive modes. Here, we provide evidence that gene flow occurred between sexual and facultatively asexual lineages of R. padi. We carefully examined the shuffling in phenotypic and genotypic variation following a sexual reproduction event that took place in the field. Combining genotypic data and phenotypic measurements showed that this gene mixing led to the production of a wide array of reproductive modes, including strictly asexual lineages. Finally, we discuss the central role played by facultatively asexual lineages on the maintenance of reproductive mode variation.

  19. The roles of sexual and asexual reproduction in the origin and dissemination of strains causing fungal infectious disease outbreaks.

    Science.gov (United States)

    Ashu, Eta Ebasi; Xu, Jianping

    2015-12-01

    Sexual reproduction commonly refers to the reproductive process in which genomes from two sources are combined into a single cell through mating and then the zygote genomes are partitioned to progeny cells through meiosis. Reproduction in the absence of mating and meiosis is referred to as asexual or clonal reproduction. One major advantage of sexual reproduction is that it generates genetic variation among progeny which may allow for faster adaptation of the population to novel and/or stressful environments. However, adaptation to stressful or new environments can still occur through mutation, in the absence of sex. In this review, we analyzed the relative contributions of sexual and asexual reproduction in the origin and spread of strains causing fungal infectious diseases outbreaks. The necessity of sex and the ability of asexual fungi to initiate outbreaks are discussed. We propose a framework that relates the modes of reproduction to the origin and propagation of fungal disease outbreaks. Our analyses suggest that both sexual and asexual reproduction can play critical roles in the origin of outbreak strains and that the rapid spread of outbreak strains is often accomplished through asexual expansion. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Identification of genes associated with asexual reproduction in Phyllosticta citricarpa mutants obtained through Agrobacterium tumefaciens transformation.

    Science.gov (United States)

    Goulin, Eduardo Henrique; Savi, Daiani Cristina; Petters, Desirrê Alexia Lourenço; Kava, Vanessa; Galli-Terasawa, Lygia; Silva, Geraldo José; Glienke, Chirlei

    2016-11-01

    Phyllosticta citricarpa is the epidemiological agent of Citrus Black Spot (CBS) disease, which is responsible for large economic losses worldwide. CBS is characterized by the presence of spores (pycnidiospores) in dark lesions of fruit, which are also responsible for short distance dispersal of the disease. The identification of genes involved in asexual reproduction of P. citricarpa can be an alternative for directional disease control. We analyzed a library of mutants obtained through Agrobacterium tumefaciens transformation system, looking for alterations in growth and reproductive structure formation. Two mutant strains were found to have lost the ability to form pycnidia. The flanking T-DNA insertion regions were identified on P. citricarpa genome by using blast analysis and further gene prediction. The predicted genes containing the T-DNA insertions were identified as Spindle Poison Sensitivity Scp3, Ion Transport protein, and Cullin Binding proteins. The Ion Transport and Cullin Binding proteins are known to be correlated with sexual and asexual reproduction in fungi; however, the exact mechanism by which these proteins act on spore formation in P. citricarpa needs to be better characterized. The Scp3 proteins are suggested here for the first time as being associated with asexual reproduction in fungus. This protein is associated with microtubule formation, and as microtubules play an essential role as spindle machinery for chromosome segregation and cytokinesis, insertions in this gene can lead to abnormal formations, such as that observed here in P. citricarpa. We suggest these genes as new targets for fungicide development and CBS disease control, by iRNA.

  1. Asexual Reproduction of Phytophthora capsici as Affected by Extracts from Agricultural and Nonagricultural Soils.

    Science.gov (United States)

    Sanogo, S

    2007-07-01

    ABSTRACT Formation of sporangia and zoospores in species of Phytophthora is known to be influenced by soil microbial and chemical composition. In Phytophthora capsici, the study of the relationship of soil chemical composition to production of sporangia and zoospores has been limited. P. capsici is a soilborne pathogen of a wide array of vegetable crops, including chile pepper (Capsicum annuum) in New Mexico. Production of sporangia and zoospores by P. capsici was evaluated in extracts of soils from three different environments in New Mexico: (i) agricultural environments with a long history of chile pepper cropping and occurrence of P. capsici (CP), (ii) agricultural environments with no history of chile pepper cropping and no occurrence of P. capsici (Non-CP), and (iii) nonagricultural environments consisting of forests and rangelands (Non-Ag). There was a significant difference in production of P. capsici asexual propagules, expressed as natural log (number of sporangia x number of zoospores), among the three environments (P = 0.0298). Production of propagules was 9 to 13% greater in Non-Ag than in CP or Non-CP environments. Stepwise multiple discriminant analysis and canonical discriminant analysis identified the edaphic variables Na, pH, P, organic matter content, and asexual propagule production as contributing the most to the separation of the three environments. Two significant (P < 0.0001) canonical discriminant functions were derived with the first function, accounting for approximately 75% of the explained variance. Based on the two discriminant functions, approximately 93, 86, and 89% of observations in CP, Non-CP, and Non-Ag environments, respectively, were classified correctly. Soils from agricultural and nonagricultural environments differentially influence production of sporangia and zoospores in P. capsici, and soil samples could be effectively classified into agricultural and nonagricultural environments based on soil chemical properties and the

  2. Effects of Ethephon, Ethylene, and 2,4-Dichlorophenoxyacetic Acid on Asexual Embryogenesis in Vitro12

    Science.gov (United States)

    Tisserat, Brent; Murashige, Toshio

    1977-01-01

    Asexual embryogenesis in Daucus carota L. `Queen Anne's Lace' callus was suppressed by Ethephon, ethylene, and 2,4-dichlorophenoxyacetic acid (2,4-D). The Ethephon effect could be attributed to volatile and nonvolatile substances. The volatile component was probably entirely ethylene. Ethylene was liberated in the cultures in direct proportion to Ethephon added to the medium. Autoclaving of Ethephon caused a substantial decrease of measurable ethylene. Continuous exposure of callus to 5 μl/l ethylene depressed somatic cell embryogenesis, but not markedly. Depression of embryogenesis by 2,4-D was unrelated to ethylene evolution. PMID:16660109

  3. Intriguing asexual life in marginal populations of the brown seaweed Fucus vesiculosus.

    Science.gov (United States)

    Tatarenkov, A; Bergström, L; Jönsson, R B; Serrão, E A; Kautsky, L; Johannesson, K

    2005-02-01

    Reproduction of attached large brown algae is known to occur only by sexual zygotes. Using microsatellites we show evolution of asexual reproduction in the bladder wrack promoting population persistence in the brackish water Baltic Sea (Fucus vesiculosus is dominated by a single clone but clonal reproduction is also present in the common form of the species. We describe a possible mechanism for vegetative reproduction of attached algae, and conclude that clonality plays an important role in persistence and dispersal of these marginal populations, in which sexual reproduction is impaired by low salinity.

  4. "In vitro" activity of gentian violet against asexual Plasmodium falciparum parasites

    Directory of Open Access Journals (Sweden)

    Shen Lin Yang

    1988-02-01

    Full Text Available In order to investigate whether gentian violet exhibited "in vitro" inhibitory activity against Plasmodium falciparum, the Authors have carried out 20 sensitivity tests according to the microtechnique described by RIECK MANN et al.5. Results have shown inhibition of schizonts'maturation at the following concentration: 1/1000; 1/1500; 1/2000; 1/2500; 1/3000 and 1/4000, thus demonstrating inhibitory activity of the tested dye against asexual blood parasites. The present data suggest gentain violet may be possibly used in the prophylaxis of transfusion-acquired malaria.

  5. On the Uselessness of Men - Comparison of Sexual and Asexual Reproduction

    Science.gov (United States)

    Stauffer, D.; Sá Martins, J. S.; de Oliveira, S. Moss

    A comparison of sexual with asexual reproduction in the Penna aging model for a single species shows the separation into males and females at a disadvantage due to the halved number of births. Also meiotic and apomictic parthenogenesis and hermaphroditism seem better than sex, even when the individuals follow the suggestion of Jan et al. to engage in sex only when their lifes are endangered by a large number of harmful mutations. In our comparison, we looked only for intrinsic effects, not for external influences like parasites or environmental catastrophes.

  6. Asexual reproduction and molecular systematics of the sea anemone Anthopleura krebsi (Actiniaria: Actiniidae).

    Science.gov (United States)

    Gomes, Paula Braga; Zamponi, Mauricio Oscar; Solé-Cava, Antonio Mateo

    2003-03-01

    In this paper we use allozyme analyses to demonstrate that individuals in Anthopleura krebsi aggregates are monoclonal. Additionally, sympatric samples of the red and the green colour-morphs of A. krebsi from Pernambuco, Brazil were genetically compared and no significant differences were observed between them (gene identity = 0.992), indicating that they do not belong to different biological species. All individuals within aggregates of the green colour-morph were found to be identical over the five polymorphic loci analysed. Such results would be extremely unlikely (P asexual reproduction in this species.

  7. Natural epigenetic variation contributes to heritable flowering divergence in a widespread asexual dandelion lineage.

    Science.gov (United States)

    Wilschut, Rutger A; Oplaat, Carla; Snoek, L Basten; Kirschner, Jan; Verhoeven, Koen J F

    2016-04-01

    Epigenetic variation has been proposed to contribute to the success of asexual plants, either as a contributor to phenotypic plasticity or by enabling transient adaptation via selection on transgenerationally stable, but reversible, epialleles. While recent studies in experimental plant populations have shown the potential for epigenetic mechanisms to contribute to adaptive phenotypes, it remains unknown whether heritable variation in ecologically relevant traits is at least partially epigenetically determined in natural populations. Here, we tested the hypothesis that DNA methylation variation contributes to heritable differences in flowering time within a single widespread apomictic clonal lineage of the common dandelion (Taraxacum officinale s. lat.). Apomictic clone members of the same apomictic lineage collected from different field sites showed heritable differences in flowering time, which was correlated with inherited differences in methylation-sensitive AFLP marker profiles. Differences in flowering between apomictic clone members were significantly reduced after in vivo demethylation using the DNA methyltransferase inhibitor zebularine. This synchronization of flowering times suggests that flowering time divergence within an apomictic lineage was mediated by differences in DNA methylation. While the underlying basis of the methylation polymorphism at functional flowering time-affecting loci remains to be demonstrated, our study shows that epigenetic variation contributes to heritable phenotypic divergence in ecologically relevant traits in natural plant populations. This result also suggests that epigenetic mechanisms can facilitate adaptive divergence within genetically uniform asexual lineages. © 2015 John Wiley & Sons Ltd.

  8. Bacterial symbiosis maintenance in the asexually reproducing and regenerating flatworm Paracatenula galateia.

    Science.gov (United States)

    Dirks, Ulrich; Gruber-Vodicka, Harald R; Leisch, Nikolaus; Bulgheresi, Silvia; Egger, Bernhard; Ladurner, Peter; Ott, Jörg A

    2012-01-01

    Bacteriocytes set the stage for some of the most intimate interactions between animal and bacterial cells. In all bacteriocyte possessing systems studied so far, de novo formation of bacteriocytes occurs only once in the host development, at the time of symbiosis establishment. Here, we present the free-living symbiotic flatworm Paracatenula galateia and its intracellular, sulfur-oxidizing bacteria as a system with previously undescribed strategies of bacteriocyte formation and bacterial symbiont transmission. Using thymidine analogue S-phase labeling and immunohistochemistry, we show that all somatic cells in adult worms - including bacteriocytes - originate exclusively from aposymbiotic stem cells (neoblasts). The continued bacteriocyte formation from aposymbiotic stem cells in adult animals represents a previously undescribed strategy of symbiosis maintenance and makes P. galateia a unique system to study bacteriocyte differentiation and development. We also provide morphological and immunohistochemical evidence that P. galateia reproduces by asexual fragmentation and regeneration (paratomy) and, thereby, vertically transmits numerous symbiont-containing bacteriocytes to its asexual progeny. Our data support the earlier reported hypothesis that the symbiont population is subjected to reduced bottleneck effects. This would justify both the codiversification between Paracatenula hosts and their Candidatus Riegeria symbionts, and the slow evolutionary rates observed for several symbiont genes.

  9. Genetic structure of two protist species (Myxogastria, Amoebozoa suggests asexual reproduction in sexual Amoebae.

    Directory of Open Access Journals (Sweden)

    Anna Maria Fiore-Donno

    Full Text Available Plasmodial slime molds (Myxogastria or Myxomycetes are common and widespread unicellular organisms that are commonly assumed to have a sexual life cycle culminating with the formation of often macroscopic fruiting bodies that efficiently disseminate spores. However, laboratory studies based on mating compatibility revealed the coexistence of asexual as well as sexual strains. To test this hypothesis in natural populations, we investigated the genetic variability of two species of the genus Lamproderma. Detailed ecological relevés were carried out in 2007 and 2009 in several deep ravines in the Elbsandsteingebirge (Saxony, south-eastern Germany. Morphological characters of 93 specimens of Lamproderma were recorded and genetic analyses, based on the small subunit ribosomal gene, the internal transcribed spacer 1 and partial elongation factor 1α sequences were carried out for 52 specimens. Genetic analyses showed the existence of two major clades, each composed of several discrete lineages. Most of these lineages were composed of several identical sequences (SSU, ITS 1 and EF-1α which is explained best by an asexual mode of reproduction. Detrended Correspondence Analysis of morphological characters revealed two morphospecies that corresponded to the two major clades, except for one genotype (Lc6, thus challenging the morphospecies concept. Genetic patterns were not related to the geographical distribution: specimens belonging to the same genotype were found in distinct ravines, suggesting effective long-distance dispersal via spores, except for the Lc6 genotype which was found only in one ravine. Implications for the morphological and biological species concept are discussed.

  10. Ribosomal RNA gene diversity, effective population size, and evolutionary longevity in asexual glomeromycota.

    Science.gov (United States)

    Vankuren, Nicholas W; den Bakker, Henk C; Morton, Joseph B; Pawlowska, Teresa E

    2013-01-01

    Arbuscular mycorrhizal fungi (phylum Glomeromycota) are among the oldest and most successful symbionts of land plants. With no evidence of sexual reproduction, their evolutionary success is inconsistent with the prediction that asexual taxa are vulnerable to extinction due to accumulation of deleterious mutations. To explore why Glomeromycota defy this prediction, we studied ribosomal RNA (rRNA) gene evolution in the Claroideoglomus lineage and estimated effective population size, N(e) , in C. etunicatum. We found that rRNA genes of these fungi exhibit unusual and complex patterns of molecular evolution. In C. etunicatum, these patterns can be collectively explained by an unexpectedly large N(e) combined with imperfect genome-wide and population-level rRNA gene repeat homogenization. The mutations accumulated in rRNA gene sequences indicate that natural selection is effective at purging deleterious mutations in the Claroideoglomus lineage, which is also consistent with the large N(e) of C. etunicatum. We propose that in the near absence of recombination, asexual reproduction involving massively multinucleate spores typical for Glomeromycota is responsible for the improved efficacy of selection relative to drift. We postulate that large effective population sizes contribute to the evolutionary longevity of Glomeromycota.

  11. Clonality and recombination in the life history of an asexual arbuscular mycorrhizal fungus.

    Science.gov (United States)

    den Bakker, Henk C; Vankuren, Nicholas W; Morton, Joseph B; Pawlowska, Teresa E

    2010-11-01

    Arbuscular mycorrhizal (AM) fungi in the phylum Glomeromycota colonize roots of the majority of land plants and assist them in the uptake of mineral nutrients in exchange for plant-assimilated carbon. In the absence of sexual reproductive structures and with asexual spore morphology conserved since the Ordovician, Glomeromycota may be one of the oldest eukaryotic lineages that rely predominantly on asexual reproduction for gene transmission. Clonal population structure detected in the majority of AM fungi examined to date supports this hypothesis. However, evidence of recombination found in few local populations suggests that genetic exchanges may be more common in these organisms than is currently recognized. To explore the significance of clonal expansion versus genetic recombination in the life history of modern Glomeromycota, we examined the global population of a cosmopolitan fungus Glomus etunicatum and made inferences about the population structure and the occurrence of recombination in the history of this species. We sampled eight loci from 84 isolates. We found that although the global population of G. etunicatum showed a pattern of significant differentiation, several haplotypes had a broad geographic distribution spanning multiple continents. Molecular variation among the sampled isolates indicated an overwhelmingly clonal population structure and suggested that clonal expansion plays an important role in the ecological success of modern Glomeromycota. In contrast, a pattern of homoplasy consistent with a history of recombination suggested that gene exchanges are not completely absent from the life history of these organisms, although they are likely to be very rare.

  12. Memory and obesity affect the population dynamics of asexual freshwater planarians

    Science.gov (United States)

    Dunkel, Jörn; Talbot, Jared; Schötz, Eva-Maria

    2011-04-01

    Asexual reproduction in multicellular organisms is a complex biophysical process that is not yet well understood quantitatively. Here, we report a detailed population study for the asexual freshwater planarian Schmidtea mediterranea, which can reproduce via transverse fission due to a large stem cell contingent. Our long-term observations of isolated non-interacting planarian populations reveal that the characteristic fission waiting time distributions for head and tail fragments differ significantly from each other. The stochastic fission dynamics of tail fragments exhibits non-negligible memory effects, implying that an accurate mathematical description of future data should be based on non-Markovian tree models. By comparing the effective growth of non-interacting planarian populations with those of self-interacting populations, we are able to quantify the influence of interactions between flatworms and physical conditions on the population growth. A surprising result is the non-monotonic relationship between effective population growth rate and nutrient supply: planarians exhibit a tendency to become 'obese' if the feeding frequency exceeds a critical level, resulting in a decreased reproduction activity. This suggests that these flatworms, which possess many genes homologous to those of humans, could become a new model system for studying dietary effects on reproduction and regeneration in multicellular organisms.

  13. [The diversity of ontogeny in animals with asexual reproduction and plasticity of early development].

    Science.gov (United States)

    Isaeva, V V

    2010-01-01

    Diversity of blastogenesis and embryogenesis in animals with different reproductive strategy and different variants of the isolation of germ lineage cells, defined in the literature as preformation, epigenesis, and somatic embryogenesis, is discussed. In the course of somatic embryogenesis (or, more precisely, blastogenesis), the oozooid that has developed from the egg is naturally cloned and forms numerous genetically and morphologically identical clonal individuals or modular units of a colony. This cloning results in amplification of the parent genotype; the subsequent sexual reproduction provides for genetic recombination, and the emergence of a huge number of larvae with dispersal function provides for reproductive success. In invertebrates that reproduce asexually, no isolation of the germ cell lineage takes place; the population of stem cell capable of realizing the complete developmental program, which includes gametogenesis and blastogenesis, is represented by a diaspora of cells dispersed in the organism and possessing evolutionarily conservative features of morphofunctional organization typical to cells of the germ lineage. The plasticity of early animal embryogenesis is revealed in experiments with embryonic cells cultivated in vitro. Asexual reproduction emerged repeatedly in the course of metazoan evolution; blastogenesis in animals of different taxa is more variable and less conservative than embryogenesis, but the installation of blastogenesis into the process of early embryogenesis undermines the conservatism of embryonic development.

  14. Asexual reproduction in introduced and native populations of the ant Cerapachys biroi.

    Science.gov (United States)

    Kronauer, Daniel J C; Pierce, Naomi E; Keller, Laurent

    2012-11-01

    Asexual reproduction is particularly common among introduced species, probably because it helps to overcome the negative effects associated with low population densities during colonization. The ant Cerapachys biroi has been introduced to tropical and subtropical islands around the world since the beginning of the last century. In this species, workers can reproduce via thelytokous parthenogenesis. Here, we use genetic markers to reconstruct the history of anthropogenic introductions of C. biroi, and to address the prevalence of female parthenogenesis in introduced and native populations. We show that at least four genetically distinct lineages have been introduced from continental Asia and have led to the species' circumtropical establishment. Our analyses demonstrate that asexual reproduction dominates in the introduced range and is also common in the native range. Given that C. biroi is the only dorylomorph ant that has successfully become established outside of its native range, this unusual mode of reproduction probably facilitated the species' worldwide spread. On the other hand, the rare occurrence of haploid males and at least one clear case of sexual recombination in the introduced range show that C. biroi has not lost the potential for sex. Finally, we show that thelytoky in C. biroi probably has a genetic rather than an infectious origin, and that automixis with central fusion is the most likely underlying cytological mechanism. This is in accordance with what is known for other thelytokous eusocial Hymenoptera.

  15. Mixed asexual and sexual reproduction in the Indo-Pacific reef coral Pocillopora damicornis.

    Science.gov (United States)

    Combosch, David J; Vollmer, Steven V

    2013-09-01

    Pocillopora damicornis is one of the best studied reef-building corals, yet it's somewhat unique reproductive strategy remains poorly understood. Genetic studies indicate that P. damicornis larvae are produced almost exclusively parthenogenetically, and yet population genetic surveys suggest frequent sexual reproduction. Using microsatellite data from over 580 larvae from 13 colonies, we demonstrate that P. damicornis displays a mixed reproductive strategy where sexual and asexual larvae are produced simultaneously within the same colony. The majority of larvae were parthenogenetic (94%), but most colonies (10 of the 13) produced a subset of their larvae sexually. Logistic regression indicates that the proportion of sexual larvae varied significantly with colony size, cycle day, and calendar day. In particular, the decrease in sexual larvae with colony size suggests that the mixed reproductive strategy changes across the life of the coral. This unique shift in reproductive strategy leads to increasingly asexual replications of successful genotypes, which (in contrast to exclusive parthenogens) have already contributed to the recombinant gene pool.

  16. Genetic structure of two protist species (Myxogastria, Amoebozoa) suggests asexual reproduction in sexual Amoebae.

    Science.gov (United States)

    Fiore-Donno, Anna Maria; Novozhilov, Yuri K; Meyer, Marianne; Schnittler, Martin

    2011-01-01

    Plasmodial slime molds (Myxogastria or Myxomycetes) are common and widespread unicellular organisms that are commonly assumed to have a sexual life cycle culminating with the formation of often macroscopic fruiting bodies that efficiently disseminate spores. However, laboratory studies based on mating compatibility revealed the coexistence of asexual as well as sexual strains. To test this hypothesis in natural populations, we investigated the genetic variability of two species of the genus Lamproderma. Detailed ecological relevés were carried out in 2007 and 2009 in several deep ravines in the Elbsandsteingebirge (Saxony, south-eastern Germany). Morphological characters of 93 specimens of Lamproderma were recorded and genetic analyses, based on the small subunit ribosomal gene, the internal transcribed spacer 1 and partial elongation factor 1α sequences were carried out for 52 specimens. Genetic analyses showed the existence of two major clades, each composed of several discrete lineages. Most of these lineages were composed of several identical sequences (SSU, ITS 1 and EF-1α) which is explained best by an asexual mode of reproduction. Detrended Correspondence Analysis of morphological characters revealed two morphospecies that corresponded to the two major clades, except for one genotype (Lc6), thus challenging the morphospecies concept. Genetic patterns were not related to the geographical distribution: specimens belonging to the same genotype were found in distinct ravines, suggesting effective long-distance dispersal via spores, except for the Lc6 genotype which was found only in one ravine. Implications for the morphological and biological species concept are discussed.

  17. A lotka-volterra model of coexistence between a sexual population and multiple asexual clones.

    Science.gov (United States)

    Pound, Graeme E; Doncaster, C Patrick; Cox, Simon J

    2002-08-21

    At carrying capacity, small advantages in competitive ability can compensate a sexual population for its two-fold disadvantage in growth capacity when facing invasion by asexual mutants. In this paper, we develop a generic analytical model to consider the ecology of a sexual population comprising equal numbers of males and females, competing for shared prey resources with multiple female-only clones. We assume that the clones arise from the sexual population and are distinguished from it only by having narrower resource niches and twice the growth capacity. For sexual populations, at density-dependent carrying capacity, intra-specific competition between clonal individuals prevents them from realizing their two-fold advantage in intrinsic growth. This prediction leads to three novel outcomes: (i) a sexual population can coexist with any number of clones, provided their combined competitive impact remains less than the impact of the clones on each other; (ii) a sexual species can immediately exclude asexual invaders if it is a fast growing and strong competitor of shared resources and also has refuge in an abundant alternative resource; (iii) the rate of accumulation of clones in a sexual population will be slowed by intra and inter-specific competition amongst the clones themselves, in addition to the competitive impact from the original sexual population.

  18. Evolution of asexual reproduction in leaves of the genus Kalanchoë.

    Science.gov (United States)

    Garcês, Helena M P; Champagne, Connie E M; Townsley, Brad T; Park, Soomin; Malhó, Rui; Pedroso, Maria C; Harada, John J; Sinha, Neelima R

    2007-09-25

    Plant somatic cells have the remarkable ability to regenerate an entire organism. Many species in the genus Kalanchoë, known as "mother of thousands," develop plantlets on the leaf margins. Using key regulators of organogenesis (STM) and embryogenesis (LEC1 and FUS3) processes, we analyzed asexual reproduction in Kalanchoë leaves. Suppression of STM abolished the ability to make plantlets. Here, we report that constitutive plantlet-forming species, like Kalanchoë daigremontiana, form plantlets by coopting both organogenesis and embryogenesis programs into leaves. These species have a defective LEC1 gene and produce nonviable seed, whereas species that produce plantlets only upon stress induction have an intact LEC1 gene and produce viable seed. The latter species are basal in the genus, suggesting that induced-plantlet formation and seed viability are ancestral traits. We provide evidence that asexual reproduction likely initiated as a process of organogenesis and then recruited an embryogenesis program into the leaves in response to loss of sexual reproduction within this genus.

  19. Multipotent epithelial cells in the process of regeneration and asexual reproduction in colonial tunicates.

    Science.gov (United States)

    Kawamura, Kazuo; Sugino, Yasuo; Sunanaga, Takeshi; Fujiwara, Shigeki

    2008-01-01

    The cellular and molecular features of multipotent epithelial cells during regeneration and asexual reproduction in colonial tunicates are described in the present study. The epicardium has been regarded as the endodermal tissue-forming epithelium in the order Enterogona, because only body fragments having the epicardium exhibit the regenerative potential. Epicardial cells in Polycitor proliferus have two peculiar features; they always accompany coelomic undifferentiated cells, and they contain various kinds of organelles in the cytoplasm. During strobilation a large amount of organelles are discarded in the lumen, and then, each tissue-forming cell takes an undifferentiated configuration. Septum cells in the stolon are also multipotent in Enterogona. Free cells with a similar configuration to the septum inhabit the hemocoel. They may provide a pool for epithelial septum cells. At the distal tip of the stolon, septum cells are columnar in shape and apparently undifferentiated. They are the precursor of the stolonial bud. In Pleurogona, the atrial epithelium of endodermal origin is multipotent. In Polyandrocarpa misakiensis, it consists of pigmented squamous cells. The cells have ultrastructurally fine granules in the cytoplasm. During budding, coelomic cells with similar morphology become associated with the atrial epithelium. Then, cells of organ placodes undergo dedifferentiation, enter a cell division cycle, and commence morphogenesis. Retinoic acid-related molecules are involved in this dedifferentiation process of multipotent cells. We conclude that in colonial tunicates two systems support the flexibility of tissue remodeling during regeneration and asexual reproduction; dedifferentiation of epithelial cells and epithelial transformation of coelomic free cells.

  20. Patterns of asexual reproduction in the fissiparous seastar Coscinasterias acutispina (Asteroidea: Echinodermata) in Japan.

    Science.gov (United States)

    Haramoto, Shinji; Komatsu, Miéko; Yamazaki, Yuji

    2007-11-01

    The morphological and anatomical characteristics of the fissiparous seastar Coscinasterias acutispina were investigated at 23 sites around Japan in order to clarify the environmental factors determining asexual reproduction. The frequency of recent fission among the sites differed, although no significant differences were evident among the three major sea areas around Japan (the Sea of Japan, Seto Inland Sea, and Pacific Ocean), indicating that the spatial variability in incidence of fission might be determined on a local scale. Morphological observations revealed that the seastars endoparasitized by Dendrogaster okadai had not undergone fission recently, suggesting that fission was suppressed by parasitism. Stepwise multiple regression analysis of the frequency of seastars that had recently undergone fission revealed that nutrient conditions affected the incidence of fission. The relationships between the pyloric caeca index and arm length ratio at the individual level suggested that good nutritional conditions were required before the occurrence of fission. Additionally, regression analysis showed that high temperature was one of the triggers of fission in C. acutispina. Thus, the process of asexual reproduction in C. acutispina appears to be governed by intricate interactions among several factors, including parasitism by D. okadai, nutrient conditions, and high temperature.

  1. Botryllus schlosseri: a model ascidian for the study of asexual reproduction.

    Science.gov (United States)

    Manni, L; Zaniolo, G; Cima, F; Burighel, P; Ballarin, L

    2007-02-01

    Botryllus schlosseri, a cosmopolitan colonial ascidian reared in the laboratory for more than 50 years, reproduces both sexually and asexually and is used as a model organism for studying a variety of biological problems. Colonies are formed of numerous, genetically identical individuals (zooids) and undergo cyclical generation changes in which the adult zooids die and are replaced by their maturing buds. Because the progression of the colonial life cycle is intimately correlated with blastogenesis, a shared staging method of bud development is required to compare data coming from different laboratories. With the present review, we aim (1) to introduce B. schlosseri as a valuable chordate model to study various biological problems and, especially, sexual and asexual development; (2) to offer a detailed description of bud development up to adulthood and the attainment of sexual maturity; (3) to re-examine Sabbadin's (1955) staging method and re-propose it as a simple tool for in vivo recognition of the main morphogenetic events and recurrent changes in the blastogenetic cycle, as it refers to the developmental stages of buds and adults.

  2. Fit for purpose: Australia's National Fitness Campaign.

    Science.gov (United States)

    Collins, Julie A; Lekkas, Peter

    2011-12-19

    During a time of war, the federal government passed the National Fitness Act 1941 to improve the fitness of the youth of Australia and better prepare them for roles in the armed services and industry. Implementation of the National Fitness Act made federal funds available at a local level through state-based national fitness councils, which coordinated promotional campaigns, programs, education and infrastructure for physical fitness, with volunteers undertaking most of the work. Specifically focused on children and youth, national fitness councils supported the provision of children's playgrounds, youth clubs and school camping programs, as well as the development of physical education in schools and its teaching and research in universities. By the time the Act was repealed in 1994, fitness had become associated with leisure and recreation rather than being seen as equipping people for everyday life and work. The emergence of the Australian National Preventive Health Agency Act 2010 offers the opportunity to reflect on synergies with its historic precedent.

  3. ProFit: Bayesian galaxy fitting tool

    Science.gov (United States)

    Robotham, A. S. G.; Taranu, D.; Tobar, R.

    2016-12-01

    ProFit is a Bayesian galaxy fitting tool that uses the fast C++ image generation library libprofit (ascl:1612.003) and a flexible R interface to a large number of likelihood samplers. It offers a fully featured Bayesian interface to galaxy model fitting (also called profiling), using mostly the same standard inputs as other popular codes (e.g. GALFIT ascl:1104.010), but it is also able to use complex priors and a number of likelihoods.

  4. Penicillium oxalicum PoFlbC regulates fungal asexual development and is important for cellulase gene expression.

    Science.gov (United States)

    Yao, Guangshan; Li, Zhonghai; Wu, Ruimei; Qin, Yuqi; Liu, Guodong; Qu, Yinbo

    2016-01-01

    Filamentous fungi can initiate vegetative growth on complex plant polysaccharides in nature through secreting a large amount of lignocellulose-degrading enzymes. These fungi develop a large amount of asexual spores to disperse and survive under harsh conditions, such as carbon and nitrogen depletion. Numerous studies report the presence of a cross-talk between asexual development and extracellular enzyme production, especially at the regulation level. This study identified and characterized a C2H2-type transcription factor called PoFlbC, which is an Aspergillus FlbC ortholog, in cellulolytic fungus Penicillium oxalicum. Results showed that the native level of PoFlbC was crucial for the normal growth and asexual development of P. oxalicum. Importantly, deletion of the PoflbC gene substantially reduced cellulase and hemicellulase productions. Comparative transcriptome analysis by RNA sequencing revealed a global downregulation of genes encoding cellulases, hemicellulases, and other proteins with functions in lignocellulose degradation. A similar defect was also observed in the OEPoflbC strain, suggesting that the production of cellulolytic enzymes was maintained by native expression of the PoflbC. In this study, an essential activator for both fungal asexual development and cellulase production was established in P. oxalicum.

  5. Protein Kinase A subunits of the ascomycete pathogen Mycosphaerella graminicola regulate asexual fructification, filamentation, melanization and osmosensing

    NARCIS (Netherlands)

    Mehrabi, R.; Kema, G.H.J.

    2006-01-01

    As in many fungi, asexual reproduction of Mycosphaerella graminicola in planta is a complex process that requires proper differentiation of the infectious hyphae in the substomatal cavities of foliar tissue before pycnidia with conidia can be formed. In this study, we have investigated the role of t

  6. Indomethacin induction of metamorphosis from the asexual stage to sexual stage in the moon jellyfish, Aurelia aurita.

    Science.gov (United States)

    Kuniyoshi, Hisato; Okumura, Izumi; Kuroda, Rie; Tsujita, Natsumi; Arakawa, Kenji; Shoji, Jun; Saito, Tamio; Osada, Hiroyuki

    2012-01-01

    We found while screening a chemical library that indomethacin, an inhibitor of prostaglandin biosynthesis, induced strobilation (metamorphosis from the asexual to sexual stage) in the moon jellyfish, Aurelia aurita. Indomethacin initiated strobilation in a dose-dependent manner, but was not involved in the progression of strobilation. Pharmacological experiments suggested that indomethacin could induce strobilation independently of prostaglandin biosynthesis.

  7. Protein Kinase A subunits of the ascomycete pathogen Mycosphaerella graminicola regulate asexual fructification, filamentation, melanization and osmosensing

    NARCIS (Netherlands)

    Mehrabi, R.; Kema, G.H.J.

    2006-01-01

    As in many fungi, asexual reproduction of Mycosphaerella graminicola in planta is a complex process that requires proper differentiation of the infectious hyphae in the substomatal cavities of foliar tissue before pycnidia with conidia can be formed. In this study, we have investigated the role of

  8. Protein Kinase A subunits of the ascomycete pathogen Mycosphaerella graminicola regulate asexual fructification, filamentation, melanization and osmosensing

    NARCIS (Netherlands)

    Mehrabi, R.; Kema, G.H.J.

    2006-01-01

    As in many fungi, asexual reproduction of Mycosphaerella graminicola in planta is a complex process that requires proper differentiation of the infectious hyphae in the substomatal cavities of foliar tissue before pycnidia with conidia can be formed. In this study, we have investigated the role of t

  9. Radical modification of the A-P axis and the evolution of asexual reproduction in Convolutriloba acoels.

    Science.gov (United States)

    Sikes, James M; Bely, Alexandra E

    2008-01-01

    Acoel worms in the genus Convolutriloba are remarkable in that closely related, morphologically very similar species reproduce asexually by dramatically different processes. Transverse fission, longitudinal fission, and reversed-polarity budding all occur within this genus, indicating an unparalleled ability to alter the A-P axis. Convolutriloba thus offers an exceptional opportunity to investigate the development and evolution of asexual reproduction. Molecular phylogenetic analysis indicates that reversed-polarity budding is ancestral and fission is derived for the genus. A clear difference between budding and fission is indicated by the development of the nervous system, which forms de novo during budding, but regenerates largely by extensions of remaining components of the nervous system during both types of fission. Despite this and other differences between fission and budding, localized muscle disorganization coupled with behaviorally mediated tearing are characteristic of both transverse fission and reversed-polarity budding (though not longitudinal fission), suggesting that a homologous tissue-separation mechanism underlies these two outwardly quite different asexual reproductive modes. We suggest that the ability to split the posterior axis field into two adjacent fields, manifested during both reversed-polarity budding and longitudinal fission, may have been a driving force behind the diversification of asexual reproductive mode in this group.

  10. Asexual propagation in the coral reef macroalga Halimeda (Chlorophyta, Bryopsidales) : production, dispersal and attachment of small fragments

    NARCIS (Netherlands)

    Walters, LJ; Coyer, JA; Hunter, CL; Beach, KS; Vroom, PS

    2002-01-01

    Siphonous, green macroalgae of the genus Halimeda are ubiquitous and ecologically important in tropical and subtropical marine environments. It has been hypothesized that the abundance of Halimeda on coral reefs is in part due to the ability of this genus to propagate asexually via vegetative fragme

  11. A Pretty Good Fit

    Science.gov (United States)

    Erickson, Tim

    2008-01-01

    We often look for a best-fit function to a set of data. This article describes how a "pretty good" fit might be better than a "best" fit when it comes to promoting conceptual understanding of functions. In a pretty good fit, students design the function themselves rather than choosing it from a menu; they use appropriate variable names; and they…

  12. Unge, sundhed og fitness

    DEFF Research Database (Denmark)

    Jensen, Jens-Ole

    2003-01-01

    Artiklen redegør for udbredelsen af fitness blandt unge og diskuterer, hvor det er blevet så populært at dyrke fitness.......Artiklen redegør for udbredelsen af fitness blandt unge og diskuterer, hvor det er blevet så populært at dyrke fitness....

  13. Fitness World - Fremtidig overlevelse

    OpenAIRE

    Rice, Kasper; Klink, Nikolaj; Nielsen, Mie; Carlson, Andre; Boy, Mikkel; Hansen, Alexander

    2015-01-01

    Our project is a case study with Fitness World as a baseline. Our project will enhance Fitness Worlds penetration on their current position on the market. Our empiricism includes both qualitative and quantitative methodical approaches by the use of an expert interview and a questionnaire survey. These methods contribute and generate general knowledge about the fitness culture in Denmark and the customers in the fitness industry. We have stated a possible strategic opportunity for Fitness Worl...

  14. Genomic analyses of primitive, wild and cultivated citrus provide insights into asexual reproduction.

    Science.gov (United States)

    Wang, Xia; Xu, Yuantao; Zhang, Siqi; Cao, Li; Huang, Yue; Cheng, Junfeng; Wu, Guizhi; Tian, Shilin; Chen, Chunli; Liu, Yan; Yu, Huiwen; Yang, Xiaoming; Lan, Hong; Wang, Nan; Wang, Lun; Xu, Jidi; Jiang, Xiaolin; Xie, Zongzhou; Tan, Meilian; Larkin, Robert M; Chen, Ling-Ling; Ma, Bin-Guang; Ruan, Yijun; Deng, Xiuxin; Xu, Qiang

    2017-05-01

    The emergence of apomixis-the transition from sexual to asexual reproduction-is a prominent feature of modern citrus. Here we de novo sequenced and comprehensively studied the genomes of four representative citrus species. Additionally, we sequenced 100 accessions of primitive, wild and cultivated citrus. Comparative population analysis suggested that genomic regions harboring energy- and reproduction-associated genes are probably under selection in cultivated citrus. We also narrowed the genetic locus responsible for citrus polyembryony, a form of apomixis, to an 80-kb region containing 11 candidate genes. One of these, CitRWP, is expressed at higher levels in ovules of polyembryonic cultivars. We found a miniature inverted-repeat transposable element insertion in the promoter region of CitRWP that cosegregated with polyembryony. This study provides new insights into citrus apomixis and constitutes a promising resource for the mining of agriculturally important genes.

  15. Obsessive compulsive disorder with psychosis NOS, in an asexual male: a diagnostic challenge.

    Science.gov (United States)

    Smigas, Thomas; Nevue, Joannie; Gadit, Amin Muhammad

    2011-10-28

    A 28-year-old asexual Malaysian male presented for emergency assessment with suicidal thoughts, paranoid delusions and increasing time spent on ritualistic behaviours that included hand washing, door checking and religious chanting. His obsessions were primarily related to counting, perfectionism, contamination and chanting. The patient found himself compelled to complete numerous rituals including chanting religiously to 1000, having to restart in the event of an error during such and also described delusions of being followed by a woman who was analysing his life pattern in order to steal from him. He then started to proclaim himself to be Buddha as he believed this would keep his dead grandmother away from him, thus avoiding supposed persecution from her. Following optimisation of both escitalpram and olanzapine, a slight reduction in the patient's ritualistic behaviour and psychotic phenomenon were witnessed.

  16. Dietary niche overlap in sympatric asexual and sexual livebearing fishes Poecilia spp.

    Science.gov (United States)

    Scharnweber, K; Plath, M; Winemiller, K O; Tobler, M

    2011-12-01

    The present study investigated the spatiotemporal patterns in trophic resource use in a system of a gynogenetic poeciliid fish, the Amazon molly Poecilia formosa, and its sexual congeners the sailfin molly Poecilia latipinna and the Atlantic molly Poecilia mexicana using gut contents analysis. No statistically significant differences in trophic resource use were found between sexual and gynogenetic species, but gut contents varied significantly across sites and over time. In addition, variation in trophic morphology (i.e. gut length) was significant across sites but not species, and laboratory experiments indicated that gut length is phenotypically plastic. Overall, trophic differentiation between coexisting asexual and sexual Poecilia appears to be minimal, and it is unlikely that niche differentiation contributes to a stable coexistence of the two reproductive forms.

  17. Candida sergipensis, a new asexual yeast species isolated from frozen pulps of tropical fruits.

    Science.gov (United States)

    Trindade, Rita C; Resende, Maria A; Pimenta, Raphael S; Lachance, Marc-André; Rosa, Carlos A

    2004-07-01

    Sixteen strains of the new yeast species Candida sergipensis have been isolated from frozen pulps of the tropical fruits umbú ( Spondias tuberosa Avr. Cam.) and mangaba ( Hancornia speciosa Gom.). Candida sergipensis was one of the prevalent species in the yeast community of these substrates. The new asexual ascomycetous yeast is phylogenetically related to Candida spandovensis and Candida sorbophila, species belonging to the Wickerhamiella clade, as evidenced by the sequences of the D1/D2 domains of their large subunit ribosomal DNAs. The species C. sergipensis and C. spandovensis can be separated on the basis of growth on 50% glucose agar, xylose and succinate, negative for the first species and positive for the second. The type culture is strain UFMG-R188 (CBS 9567).

  18. The More the Merrier?. Entropy and Statistics of Asexual Reproduction in Freshwater Planarians

    Science.gov (United States)

    Quinodoz, Sofia; Thomas, Michael A.; Dunkel, Jörn; Schötz, Eva-Maria

    2011-04-01

    The trade-off between traits in life-history strategies has been widely studied for sexual and parthenogenetic organisms, but relatively little is known about the reproduction strategies of asexual animals. Here, we investigate clonal reproduction in the freshwater planarian Schmidtea mediterranea, an important model organism for regeneration and stem cell research. We find that these flatworms adopt a randomized reproduction strategy that comprises both asymmetric binary fission and fragmentation (generation of multiple offspring during a reproduction cycle). Fragmentation in planarians has primarily been regarded as an abnormal behavior in the past; using a large-scale experimental approach, we now show that about one third of the reproduction events in S. mediterranea are fragmentations, implying that fragmentation is part of their normal reproductive behavior. Our analysis further suggests that certain characteristic aspects of the reproduction statistics can be explained in terms of a maximum relative entropy principle.

  19. Plant germline formation: common concepts and developmental flexibility in sexual and asexual reproduction.

    Science.gov (United States)

    Schmidt, Anja; Schmid, Marc W; Grossniklaus, Ueli

    2015-01-15

    The life cycle of flowering plants alternates between two heteromorphic generations: a diploid sporophytic generation and a haploid gametophytic generation. During the development of the plant reproductive lineages - the germlines - typically, single sporophytic (somatic) cells in the flower become committed to undergo meiosis. The resulting spores subsequently develop into highly polarized and differentiated haploid gametophytes that harbour the gametes. Recent studies have provided insights into the genetic basis and regulatory programs underlying cell specification and the acquisition of reproductive fate during both sexual reproduction and asexual (apomictic) reproduction. As we review here, these recent advances emphasize the importance of transcriptional, translational and post-transcriptional regulation, and the role of epigenetic regulatory pathways and hormonal activity.

  20. Transmission of a heterologous clade C Symbiodinium in a model anemone infection system via asexual reproduction.

    Science.gov (United States)

    Chen, Wan-Nan U; Hsiao, Ya-Ju; Mayfield, Anderson B; Young, Ryan; Hsu, Ling-Lan; Peng, Shao-En

    2016-01-01

    Anemones of genus Exaiptasia are used as model organisms for the study of cnidarian-dinoflagellate (genus Symbiodinium) endosymbiosis. However, while most reef-building corals harbor Symbiodinium of clade C, Exaiptasia spp. anemones mainly harbor clade B Symbiodinium (ITS2 type B1) populations. In this study, we reveal for the first time that bleached Exaiptasia pallida anemones can establish a symbiotic relationship with a clade C Symbiodinium (ITS2 type C1). We further found that anemones can transmit the exogenously supplied clade C Symbiodinium cells to their offspring by asexual reproduction (pedal laceration). In order to corroborate the establishment of stable symbiosis, we used microscopic techniques and genetic analyses to examine several generations of anemones, and the results of these endeavors confirmed the sustainability of the system. These findings provide a framework for understanding the differences in infection dynamics between homologous and heterologous dinoflagellate types using a model anemone infection system.

  1. Genetic and environmental effects on morphology and asexual reproduction in the moss, Bryum bicolor

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, A.J. (Ithaca College, NY (USA))

    A distinctive form of Bryum bicolor, characterized by stoutly excurrent costae and abundant asexual gemmae, occurs on heavy metal-contaminated tailings of the Conrad Hill Mine in the Piedmont of North Carolina. Plants from two mine site populations, plus two other populations from Richmond, Virginia, were grown on three types of soil in order to determine the degree to which morphological traits, including the number of gemmae per plant, can be modified by substrate. All populations grew equally well in the mine soil, and there was no evidence that plants from the mine site populations were physiologically adapted for growth on the contaminated tailings. Leaf dimensions, costa length, and number of gemmae per stem were strongly influenced by substrate, although some differences between populations were maintained under experimental conditions. Populations also differed in the efficacy with which plants regenerated from gametophytic fragments.

  2. Effects of genotoxicity and its consequences at the population level in sexual and asexual Artemia assessed by analysis of inter-simple sequence repeats (ISSR).

    Science.gov (United States)

    Sukumaran, Sandhya; Grant, Alastair

    2013-09-18

    There is considerable evidence that genetic damage in organisms occurs in the environment as a result of exposure to genotoxins and ionising radiation, but we have limited understanding of the extent to which this results in adverse consequences at a population level. We used inter-simple sequence repeat (ISSR) markers to quantify genotoxic effects of the mutagen ethylmethane sulfonate (EMS) on a sexual (Artemia franciscana) and an asexual (Artemia parthenogenetica) species of brine shrimp. The method provides information similar to that obtained with assessment of RAPD (random amplification of polymorphic DNA) but is more robust. Genetic damage was transmitted to the F1 generation in both Artemia species, but the sexual species showed a greater degree of recovery, as shown by higher values of genomic template stability. There was a strong correlation between DNA damage and effects on individual fitness parameters: size, survival, reproduction and population growth. These effects persisted into the F2 generation in A. parthenogenetica, but in the sexual A. franciscana only effects on fecundity continued beyond the exposed generation, even though there were substantial alterations in ISSR patterns in the F1 generation. Genetic biomarkers can thus be indicative of effects at the population level, but sexually reproducing species have a considerable assimilative capacity for the effects of genotoxins.

  3. RACK1 regulates mesenchymal cell recruitment during sexual and asexual reproduction of budding tunicates.

    Science.gov (United States)

    Tatzuke, Yuki; Sunanaga, Takeshi; Fujiwara, Shigeki; Kawamura, Kaz

    2012-08-15

    A homolog of receptor for activated protein kinase C1 (RACK1) was cloned from the budding tunicate Polyandrocarpa misakiensis. By RT-PCR and in situ hybridization analyses, PmRACK1 showed biphasic gene expression during asexual and sexual reproduction. In developing buds, the signal was exclusively observed in the multipotent atrial epithelium and undifferentiated mesenchymal cells that contributed to morphogenesis by the mesenchymal-epithelial transition (MET). In juvenile zooids, the signal was first observable in germline precursor cells that arose as mesenchymal cell aggregated in the ventral hemocoel. In mature zooids, the germinal epithelium in the ovary and the pharynx were the most heavily stained parts. GFP reporter assay indicated that the ovarian expression of PmRACK1 was constitutive from germline precursor cells to oocytes. To elucidate the in vivo function of PmRACK1, RNA interference was challenged. When growing buds were incubated with 5 nmol/mL siRNA, most mesenchymal cells remained round and appeared to have no interactions with the extracellular matrix (ECM), causing lower activity of MET without any apparent effects on cell proliferation. The resultant zooids became growth-deficient. The dwarf zooids did not form buds or mature gonads. Prior to RNAi, buds were treated with human BMP4 that could induce PmRACK1 expression, which resulted in MET activity. We conclude that in P. misakiensis, PmRACK1 plays roles in mesenchymal cell recruitment during formation of somatic and gonad tissues, which contributes to zooidal growth and sexual and asexual reproduction.

  4. Potato (Solanum tuberosum) greenhouse tuber production as an assay for asexual reproduction effects from herbicides.

    Science.gov (United States)

    Olszyk, David; Pfleeger, Thomas; Lee, E Henry; Plocher, Milton

    2010-01-01

    The present study determined whether young potato plants can be used as an assay to indicate potential effects of pesticides on asexual reproduction. Solanum tuberosum (Russet Burbank) plants were grown from seed pieces in a mineral soil in pots under greenhouse conditions. Plants were treated with herbicides (cloransulam, dicamba, glyphosate, imazapyr, primsulfuron, sulfometuron, or tribenuron) at simulated drift levels [asexual reproductive responses to herbicides, especially acetolactate synthase inhibitors.

  5. MUNI-FITS-Utils

    Science.gov (United States)

    Chrastina, M.; Zejda, M.; Mikulášek, Z.

    2010-12-01

    The FITS standard allows arbitrary use of name-space for keywords, except some reserved keywords. Result of this freedom is that several keywords have the same meaning. Similar problem is that values of keywords have different physical units. These facts complicate automated data processing and also creation of FITS file archives with simple structure. MUNI-FITS-Utils is a package of Python scripts which have been developed in PyFITS, a Python FITS Module. Scripts are user-friendly and allow manipulating FITS headers to get uniform shape. Further functions will be added soon.

  6. FIT3D: Fitting optical spectra

    Science.gov (United States)

    Sánchez, S. F.; Pérez, E.; Sánchez-Blázquez, P.; González, J. J.; Rosales-Ortega, F. F.; Cano-Díaz, M.; López-Cobá, C.; Marino, R. A.; Gil de Paz, A.; Mollá, M.; López-Sánchez, A. R.; Ascasibar, Y.; Barrera-Ballesteros, J.

    2016-09-01

    FIT3D fits optical spectra to deblend the underlying stellar population and the ionized gas, and extract physical information from each component. FIT3D is focused on the analysis of Integral Field Spectroscopy data, but is not restricted to it, and is the basis of Pipe3D, a pipeline used in the analysis of datasets like CALIFA, MaNGA, and SAMI. It can run iteratively or in an automatic way to derive the parameters of a large set of spectra.

  7. The Plasmodium falciparum, Nima-related kinase Pfnek-4: a marker for asexual parasites committed to sexual differentiation

    Directory of Open Access Journals (Sweden)

    Reininger Luc

    2012-07-01

    Full Text Available Abstract Background Malaria parasites undergo, in the vertebrate host, a developmental switch from asexual replication to sexual differentiation leading to the formation of gametocytes, the only form able to survive in the mosquito vector. Regulation of the onset of the sexual phase remains largely unknown and represents an important gap in the understanding of the parasite’s complex biology. Methods The expression and function of the Nima-related kinase Pfnek-4 during the early sexual development of the human malaria parasite Plasmodium falciparum were investigated, using three types of transgenic Plasmodium falciparum 3D7 lines: (i episomally expressing a Pfnek-4-GFP fusion protein under the control of its cognate pfnek-4 promoter; (ii episomally expressing negative or positive selectable markers, yeast cytosine deaminase-uridyl phosphoribosyl transferase, or human dihydrofolate reductase, under the control of the pfnek-4 promoter; and (iii lacking a functional pfnek-4 gene. Parasite transfectants were analysed by fluorescence microscopy and flow cytometry. In vitro growth rate and gametocyte formation were determined by Giemsa-stained blood smears. Results The Pfnek-4-GFP protein was found to be expressed in stage II to V gametocytes and, unexpectedly, in a subset of asexual-stage parasites undergoing schizogony. Culture conditions stimulating gametocyte formation resulted in significant increase of this schizont subpopulation. Moreover, sorted asexual parasites expressing the Pfnek-4-GFP protein displayed elevated gametocyte formation when returned to in vitro culture in presence of fresh red blood cells, when compared to GFP- parasites from the same initial population. Negative selection of asexual parasites expressing pfnek-4 showed a marginal reduction in growth rate, whereas positive selection caused a marked reduction in parasitaemia, but was not sufficient to completely abolish proliferation. Pfnek-4- clones are not affected in their

  8. Family Activities for Fitness

    Science.gov (United States)

    Grosse, Susan J.

    2009-01-01

    This article discusses how families can increase family togetherness and improve physical fitness. The author provides easy ways to implement family friendly activities for improving and maintaining physical health. These activities include: walking, backyard games, and fitness challenges.

  9. Reciprocal sign epistasis between frequently experimentally evolved adaptive mutations causes a rugged fitness landscape.

    Directory of Open Access Journals (Sweden)

    Daniel J Kvitek

    2011-04-01

    Full Text Available The fitness landscape captures the relationship between genotype and evolutionary fitness and is a pervasive metaphor used to describe the possible evolutionary trajectories of adaptation. However, little is known about the actual shape of fitness landscapes, including whether valleys of low fitness create local fitness optima, acting as barriers to adaptive change. Here we provide evidence of a rugged molecular fitness landscape arising during an evolution experiment in an asexual population of Saccharomyces cerevisiae. We identify the mutations that arose during the evolution using whole-genome sequencing and use competitive fitness assays to describe the mutations individually responsible for adaptation. In addition, we find that a fitness valley between two adaptive mutations in the genes MTH1 and HXT6/HXT7 is caused by reciprocal sign epistasis, where the fitness cost of the double mutant prohibits the two mutations from being selected in the same genetic background. The constraint enforced by reciprocal sign epistasis causes the mutations to remain mutually exclusive during the experiment, even though adaptive mutations in these two genes occur several times in independent lineages during the experiment. Our results show that epistasis plays a key role during adaptation and that inter-genic interactions can act as barriers between adaptive solutions. These results also provide a new interpretation on the classic Dobzhansky-Muller model of reproductive isolation and display some surprising parallels with mutations in genes often associated with tumors.

  10. Reciprocal sign epistasis between frequently experimentally evolved adaptive mutations causes a rugged fitness landscape.

    Directory of Open Access Journals (Sweden)

    Daniel J Kvitek

    2011-04-01

    Full Text Available The fitness landscape captures the relationship between genotype and evolutionary fitness and is a pervasive metaphor used to describe the possible evolutionary trajectories of adaptation. However, little is known about the actual shape of fitness landscapes, including whether valleys of low fitness create local fitness optima, acting as barriers to adaptive change. Here we provide evidence of a rugged molecular fitness landscape arising during an evolution experiment in an asexual population of Saccharomyces cerevisiae. We identify the mutations that arose during the evolution using whole-genome sequencing and use competitive fitness assays to describe the mutations individually responsible for adaptation. In addition, we find that a fitness valley between two adaptive mutations in the genes MTH1 and HXT6/HXT7 is caused by reciprocal sign epistasis, where the fitness cost of the double mutant prohibits the two mutations from being selected in the same genetic background. The constraint enforced by reciprocal sign epistasis causes the mutations to remain mutually exclusive during the experiment, even though adaptive mutations in these two genes occur several times in independent lineages during the experiment. Our results show that epistasis plays a key role during adaptation and that inter-genic interactions can act as barriers between adaptive solutions. These results also provide a new interpretation on the classic Dobzhansky-Muller model of reproductive isolation and display some surprising parallels with mutations in genes often associated with tumors.

  11. Distribution, phenology and demography of sympatric sexual and asexual dandelions (Taraxacum officinale s.l.): geographic parthenogenesis on a small scale

    NARCIS (Netherlands)

    Verduijn, M.H.; van Dijk, P.J.; Van Damme, J.M.M.

    2004-01-01

    In many plant and animal species, sexual and asexual forms have different geographical distributions ('geographic parthenogenesis'). The common dandelion Taraxacum officinale s.l. provides a particularly clear example of differing distributions: diploid sexuals are restricted to southern and central

  12. Distribution, phenology and demography of sympatric sexual and asexual dandelions (Taraxacum officinale s.l.): geographic parthenogenesis on a small scale

    NARCIS (Netherlands)

    Verduijn, M.H.; van Dijk, P.J.; Van Damme, J.M.M.

    2004-01-01

    In many plant and animal species, sexual and asexual forms have different geographical distributions ('geographic parthenogenesis'). The common dandelion Taraxacum officinale s.l. provides a particularly clear example of differing distributions: diploid sexuals are restricted to southern and central

  13. Effect of mutators on adaptability in time-varying fitness landscapes

    Science.gov (United States)

    Gorodetsky, Pavel; Tannenbaum, Emmanuel

    2008-04-01

    This Brief Report studies the quasispecies dynamics of a population capable of genetic repair evolving on a time-dependent fitness landscape. We develop a model that considers an asexual population of single-stranded, conservatively replicating genomes, whose only source of genetic variation is due to copying errors during replication. We consider a time-dependent, single-fitness-peak landscape where the master sequence changes by a single point mutation at every time τ . We are able to analytically solve for the evolutionary dynamics of the population in the point-mutation limit. In particular, our model provides an analytical expression for the fraction of mutators in the dynamic fitness landscape that agrees well with results from stochastic simulations.

  14. Quasispecies on Fitness Landscapes.

    Science.gov (United States)

    Schuster, Peter

    2016-01-01

    Selection-mutation dynamics is studied as adaptation and neutral drift on abstract fitness landscapes. Various models of fitness landscapes are introduced and analyzed with respect to the stationary mutant distributions adopted by populations upon them. The concept of quasispecies is introduced, and the error threshold phenomenon is analyzed. Complex fitness landscapes with large scatter of fitness values are shown to sustain error thresholds. The phenomenological theory of the quasispecies introduced in 1971 by Eigen is compared to approximation-free numerical computations. The concept of strong quasispecies understood as mutant distributions, which are especially stable against changes in mutations rates, is presented. The role of fitness neutral genotypes in quasispecies is discussed.

  15. Evidence of pheromonal constancy among sexual and asexual females in a population of fall cankerworm,Alsophila pometaria (Lepidoptera: Geometridae).

    Science.gov (United States)

    Mitter, C; Klun, J A

    1987-08-01

    The compounds (Z,Z,Z)-3,6,9-nonadecatriene (I), (Z,Z,Z,E)-(II), and (Z,Z,Z,Z)-3,6,9,11-nonadecatetraene (III) have been implicated as components of the female sex pheromone of the fall cankerworm. Chromatographie determination of the proportions of these compounds in individual females of sympatric asexual and sexual reproductive forms of the species, with concurrent analysis of the electrophoretic profiles of the same females, showed that the I: II: III proportion of compounds was constant across electrophoretically differing asexual genotypes and between these and the sexual form. Life-history characters, in contrast, typically show great variation among these genetic groups. The results indicate that pheromonal constancy is maintained in a reproductive system that is theoretically vulnerable to selective pressures that would lead to heterogeneity in the species' pheromonal communication channel.

  16. speciation through asexuality in fish: postzygotic reproductive isolation may be completed in spite of fertility of hybrids

    Directory of Open Access Journals (Sweden)

    Karel Janko

    2015-12-01

    Altogether, it appears that initiation of hybrid asexuality and the completion of speciation process through formation of postRIMs are interconnected phenomena. Both processes are linked to the genetic divergence of hybridizing taxa: initially, hybridization between little diverged species leads to recombinant and fertile hybrids allowing intensive gene flow. As the hybridizing taxa continue to diverge, clonally reproducing hybrid females and sterile males become dominant and the gene flow ceases. The speciation may therefore be completed through asexuality of hybrids The work was supported by grant no. 13-12580S provided by the Czech Science Foundation (www.gacr.cz. Further support was provided by the Academy of Sciences of the Czech Republic (www.cas.cz by the grant no. RVO 67985904

  17. Asexual reproduction does not produce clonal populations of the brooding coral Pocillopora damicornis on the Great Barrier Reef, Australia

    Science.gov (United States)

    Sherman, C. D. H.; Ayre, D. J.; Miller, K. J.

    2006-03-01

    We have investigated the relationship between genotypic diversity, the mode of production of brooded larvae and disturbance in a range of reef habitats, in order to resolve the disparity between the reproductive mode and population structure reported for the brooding coral Pocillopora damicornis. Within 14 sites across six habitats, the ratio of the observed ( G o) to the expected ( G e) genotypic diversity ranged from 69 to 100% of that expected for random mating. At three other sites in two habitats the G o /G e ranged from 35 to 53%. Two of these sites were recently bleached, suggesting that asexual recruitment may be favoured after disturbance. Nevertheless, our data suggest that brooded larvae, from each of five habitats surveyed, were asexually produced. While clonal recruitment may be important in disturbed habitats, the lack of clonality detected, both in this and earlier surveys of 40 other sites, implies that a disturbance is normally insufficient to explain this species’ continued investment in clonal reproduction.

  18. La correlación entre la poliploidía y la reproducción asexual

    OpenAIRE

    M. Vallejo-Marín

    2014-01-01

    La poliploidía, la existencia de más de dos juegos de cromosomas apareados u homólogos, en un individuo, y la reproducción asexual por vías apomíctica o vegetativa, están fuertemente correlacionadas. Sin embargo hasta la fecha, pocos estudios han investigado directamente las hipótesis que intentan explicar el origen evolutivo de esta correlación. En esta nota, presentaré algunas de las hipótesis propuestas para explicar la correlación entre poliploidía y la reproducción asexual, y discutiré d...

  19. Genotyping an Emiliania huxleyi (Prymnesiophyceae bloom event in the North Sea reveals evidence of asexual reproduction

    Directory of Open Access Journals (Sweden)

    S. A. Krueger-Hadfield

    2014-03-01

    Full Text Available Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm. Hay and Mohler (Prymnesiophyceae is likely to be such a species as it is the most conspicuous extant calcareous phytoplankton species in our oceans with generation times of 1 day−1. Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 UK Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited Psex values of less than 0.05 indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloom-forming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges our current assumption that sex is the predominant mode of reproduction during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these

  20. Genotyping an Emiliania huxleyi (prymnesiophyceae) bloom event in the North Sea reveals evidence of asexual reproduction

    Science.gov (United States)

    Krueger-Hadfield, S. A.; Balestreri, C.; Schroeder, J.; Highfield, A.; Helaouët, P.; Allum, J.; Moate, R.; Lohbeck, K. T.; Miller, P. I.; Riebesell, U.; Reusch, T. B. H.; Rickaby, R. E. M.; Young, J.; Hallegraeff, G.; Brownlee, C.; Schroeder, D. C.

    2014-09-01

    Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) is likely to be such a species, as it is the most conspicuous extant calcareous phytoplankton species in our oceans with growth rates of 1 day-1. Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 United Kingdom Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs) encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited Psex values of less than 0.05, indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloom-forming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges the current assumption that sexual reproduction predominates during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these populations still

  1. Omics data reveal the unusual asexual-fruiting nature and secondary metabolic potentials of the medicinal fungus Cordyceps cicadae.

    Science.gov (United States)

    Lu, Yuzhen; Luo, Feifei; Cen, Kai; Xiao, Guohua; Yin, Ying; Li, Chunru; Li, Zengzhi; Zhan, Shuai; Zhang, Huizhan; Wang, Chengshu

    2017-08-30

    Ascomycete Cordyceps species have been using as valued traditional Chinese medicines. Particularly, the fruiting bodies of Cordyceps cicadae (syn. Isaria cicadae) have long been utilized for the treatment of chronic kidney disease. However, the genetics and bioactive chemicals in this fungus have been largely unexplored. In this study, we performed comprehensive omics analyses of C. cicadae, and found that, in contrast to other Cordyceps fungi, C. cicadae produces asexual fruiting bodies with the production of conidial spores instead of the meiotic ascospores. Genome sequencing and comparative genomic analysis indicate that the protein families encoded by C. cicadae are typical of entomopathogenic fungi, including the expansion of proteases and chitinases for targeting insect hosts. Interestingly, we found that the MAT1-2 mating-type locus of the sequenced strain contains an abnormally truncated MAT1-1-1 gene. Gene deletions revealed that asexual fruiting of C. cicadae is independent of the MAT locus control. RNA-seq transcriptome data also indicate that, compared to growth in a liquid culture, the putative genes involved in mating and meiosis processes were not up-regulated during fungal fruiting, further supporting asexual reproduction in this fungus. The genome of C. cicadae encodes an array of conservative and divergent gene clusters for secondary metabolisms. Based on our analysis, the production of known carcinogenic metabolites by this fungus could be potentially precluded. However, the confirmed production of oosporein raises health concerns about the frequent consumption of fungal fruiting bodies. The results of this study expand our knowledge of fungal genetics that asexual fruiting can occur independent of the MAT locus control. The obtained genomic and metabolomic data will benefit future investigations of this fungus for medicinal uses.

  2. Dynamic formation of asexual diploid and polyploid lineages: multilocus analysis of Cobitis reveals the mechanisms maintaining the diversity of clones.

    Directory of Open Access Journals (Sweden)

    Karel Janko

    Full Text Available Given the hybrid genomic constitutions and increased ploidy of many asexual animals, the identification of processes governing the origin and maintenance of clonal diversity provides useful information about the evolutionary consequences of interspecific hybridization, asexuality and polyploidy. In order to understand the processes driving observed diversity of biotypes and clones in the Cobitis taenia hybrid complex, we performed fine-scale genetic analysis of Central European hybrid zone between two sexual species using microsatellite genotyping and mtDNA sequencing. We found that the hybrid zone is populated by an assemblage of clonally (gynogenetically reproducing di-, tri- and tetraploid hybrid lineages and that successful clones, which are able of spatial expansion, recruit from two ploidy levels, i.e. diploid and triploid. We further compared the distribution of observed estimates of clonal ages to theoretical distributions simulated under various assumptions and showed that new clones are most likely continuously recruited from ancestral populations. This suggests that the clonal diversity is maintained by dynamic equilibrium between origination and extinction of clonal lineages. On the other hand, an interclonal selection is implied by nonrandom spatial distribution of individual clones with respect to the coexisting sexual species. Importantly, there was no evidence for sexually reproducing hybrids or clonally reproducing non-hybrid forms. Together with previous successful laboratory synthesis of clonal Cobitis hybrids, our data thus provide the most compelling evidence that 1 the origin of asexuality is causally linked to interspecific hybridization; 2 successful establishment of clones is not restricted to one specific ploidy level and 3 the initiation of clonality and polyploidy may be dynamic and continuous in asexual complexes.

  3. Relative importance of sexual and asexual reproduction for range expansion of Spartina alterniflora in different tidal zones on Chinese coast

    Science.gov (United States)

    Liu, Huiyu; Lin, Zhenshan; Zhang, Mingyang; Qi, Xiangzhen

    2017-02-01

    In this paper, based on spatially explicit individual-based model and global sensitivity analysis, the relative importance of sexual and asexual reproduction for range expansion of Spartina alterniflora in different tidal zones during different invasion stages has been revealed. The results showed that: 1) sexual reproduction is thought to accelerate the range expansion in middle and high tidal zones; 2) seed dispersal and adult survival rate are the two most important for range expansion of S. alterniflora during most invasion stages in all tidal zones. However, in high tidal zone, the importance of seed dispersal distance is much less than in low and middle tidal zones, and that of sexual reproduction is also great, which cannot be ignored. In middle tidal zone, the importance of adult survival rate is less important than in high and low tidal zones, and is very close to asexual reproduction. Moreover, there are significant fluctuations among the importance of different parameters except seed dispersal distance, indicating strong interactions. 3) the importance of adult survival rate and asexual reproduction is much greater than seed dispersal distance during early invasion. Especially, their importance is much higher during early and middle invasion stages in high tidal zone. During early invasion stages, the interactions among different parameters are very strong. To enhance the invasion control efficiency, it is necessary to take different control measures according to different tidal zones and invasion stages.

  4. Distribution of Phoxinus eos, Phoxinus neogaeus, and their asexually-reproducing hybrids (Pisces: Cyprinidae in Algonquin Provincial Park, Ontario.

    Directory of Open Access Journals (Sweden)

    Jonathan A Mee

    Full Text Available Hybrid Phoxinus are one of the few asexually reproducing vertebrates species. The distribution of hybrid Phoxinus among lakes in Algonquin Park, Ontario, was evaluated relative to the distribution of parental species and relative to physiochemical lake characteristics. No association between the distribution of hybrids and the distribution of parental species was found, suggesting that the hybrids can successfully coexist with either parental species. In addition, we found no association between hybrid distribution and the physiochemical characteristics of lakes, suggesting that the hybrids are generalists with respect to the ecological niches available in Algonquin Park. There was a difference between the physiochemical characteristics of lakes with and without the parental species P. neogaeus. The lakes containing P. neogaeus were lower elevation than the lakes containing the other parental species, P. eos. The difference in distribution between the parental species may therefore be due to different dispersal abilities, to later arrival following post-glacial dispersal, or to differences in ecology. These results suggest that asexual reproduction is a successful strategy for hybrid Phoxinus in Algonquin Park because these sperm-dependent asexual hybrids are able to survive and persist regardless of which parental species is present, and regardless of the physiochemical characteristics of their habitat.

  5. Effect of tropical storms on sexual and asexual reproduction in coral Pocillopora verrucosa subpopulations in the Gulf of California

    Science.gov (United States)

    Aranceta-Garza, F.; Balart, E. F.; Reyes-Bonilla, H.; Cruz-Hernández, P.

    2012-12-01

    Pocillopora verrucosa is a branching, reef-building coral, and a simultaneous hermaphrodite that reproduces sexually and asexually by fragmentation. In the Gulf of California, local P. verrucosa populations have mixed modes of reproduction which vary in frequency by site. Sexual and asexual reproductions were assessed using multi-locus genotypes deriving from six microsatellite loci at every location. Clone frequencies varied from 0.30 at Loreto to 0.96 in the San Lorenzo Channel. Isla Espíritu Santo and the San Lorenzo Channel were mostly asexual subpopulations, presented the lowest genotypic richness ( N g / N = 0.1-0.12) and genotypic diversity ( G o / G e = 0.04), and were dominated by one or two multi-loci genotypes ( G o / N g = 0.35-0.45). Loreto, El Portugués, and Cabo Pulmo were mostly sexual with high Ng/ N (0.80-0.74) and G o / G e (0.52-0.58) and did not show domination by a single multi-locus genotype ( G o / N g = 0.70-0.74). There was a significant relationship ( P reproduction modes has different maintenance strategies at a regional and even local level among populations indicating the crucial role that storms play in population structure.

  6. La correlación entre la poliploidía y la reproducción asexual

    Directory of Open Access Journals (Sweden)

    M. Vallejo-Marín

    2014-01-01

    Full Text Available La poliploidía, la existencia de más de dos juegos de cromosomas apareados u homólogos, en un individuo, y la reproducción asexual por vías apomíctica o vegetativa, están fuertemente correlacionadas. Sin embargo hasta la fecha, pocos estudios han investigado directamente las hipótesis que intentan explicar el origen evolutivo de esta correlación. En esta nota, presentaré algunas de las hipótesis propuestas para explicar la correlación entre poliploidía y la reproducción asexual, y discutiré de qué forma los análisis filogenéticos nos pueden ayudar para establecer la fuerza y la causalidad de esta asociación. Adicionalmente, presentaré un ejemplo de cómo sistemas alopoliploides de evolución reciente pueden servir para estudiar la interacción entre poliploidía y la reproducción asexual, y para probar hipótesis específicas derivadas de estudios correlativos y comparativos.

  7. A novel invertebrate trophic factor related to invertebrate neurotrophins is involved in planarian body regional survival and asexual reproduction.

    Science.gov (United States)

    Bueno, David; Fernàndez-Rodríguez, Juana; Cardona, Albert; Hernàndez-Hernàndez, Victor; Romero, Rafael

    2002-12-15

    Trophic factors are a heterogeneous group of molecules that promote cell growth and survival. In freshwater planarians, the small secreted protein TCEN49 is linked to the regional maintenance of the planarian central body region. To investigate its function in vivo, we performed loss-of-function and gain-of-function experiments by RNA interference and by the implantation of microbeads soaked in TCEN49, respectively. We show that TCEN49 behaves as a trophic factor involved in central body region neuron survival. In planarian tail regenerates, tcen49 expression inhibition by double-stranded RNA interference causes extensive apoptosis in various cell types, including nerve cells. This phenotype is rescued by the implantation of microbeads soaked in TCEN49 after RNA interference. On the other hand, in organisms committed to asexual reproduction, both tcen49 mRNA and its protein are detected not only in the central body region but also in the posterior region, expanding from cells close to the ventral nerve chords. In some cases, the implantation of microbeads soaked in TCEN49 in the posterior body region drives organisms to reproduce asexually, and the inhibition of tcen49 expression obstructs this process, suggesting a link between the central nervous system, TCEN49, regional induction, and asexual reproduction. Finally, the distribution of TCEN49 cysteine and tyrosine residues also points to a common evolutionary origin for TCEN49 and molluscan neurotrophins.

  8. The role of sexual and asexual reproduction in structuring high latitude populations of the reef coral Pocillopora damicornis.

    Science.gov (United States)

    Miller, K J; Ayre, D J

    2004-06-01

    The genotypic composition of populations of the asexually viviparous coral Pocillopora damicornis varies in a manner that challenges classical models of the roles of sexual and asexual reproduction. On the geographically isolated Hawaiian reefs and high latitude reefs in Western Australia, P. damicornis populations are highly clonal although it has been argued that sexual reproduction via broadcast spawning generates widely dispersed colonists. In contrast, on eastern Australia's tropical Great Barrier Reef populations show little evidence of clonality. Here, we compare the genotypic diversity of adult and juvenile colonies of P. damicornis at seven sites on eastern Australia's high latitude Lord Howe Island reefs to determine if levels of clonality vary with habitat heterogeneity and age of colonies (as predicted by theory) or alternatively if clonality is again always high as for other isolated reef systems. We found 55-100% of the genotypic diversity expected for random mating at all seven sites and little evidence of asexual recruitment irrespective of habitat heterogeneity (sheltered versus wave exposed) or colony age. We found reduced levels of genetic diversity compared with tropical reefs (2.75 versus 4 alleles/locus), which supports earlier findings that Lord Howe Island is an isolated reef system. Furthermore, heterozygote deficits coupled with significant genetic subdivision among sites (FST=0.102+/-0.03) is typical of populations that have limited larval connections and are inbred. We conclude that the genetic structure of P. damicornis at Lord Howe Island reflects populations that are maintained through localised recruitment of sexually produced larvae.

  9. TECHNOLOGICAL ASPECTS CONCERNING PRODUCTION ON ASEXUAL TRACK OF ORNAMENTAL CULTURE OF ALOE ARBORESCENS

    Directory of Open Access Journals (Sweden)

    Mădălina Doltu

    2012-12-01

    Full Text Available Research conducted in culture of Aloe arborescens Mill., in conditions of protected area (greenhouse, had to watch some of technological aspects to obtain some in pot ornamentals plants, competitive plants for european market. Experience has included plants of Aloe arborescens Mill., aged 1-5 years, obtained by vegetative multiplying, asexual. Production technology was applied to aloe plants (multiplying, transplanting, maintenance, taking into account the ecological requirements of specie and possibilities of using automated artificial factors influencing microclimate (shading, ventilation, cooling of production space. Researches has established technological aspects concerning production of plants, to satisfy requirements of specie, for obtained some specimens by superior decorative quality. The results of experienced technology indicate quality of morphological characters, growth increases important of decorative elements (height, leaves, shoots, appearance of flowering at plants aged two years. Culture of Aloe arborescens Mill. in pot, can be practiced all year, just in conditions of protected areas. This culture, realized in the purpose for obtain decorative plants, is a valuable activity of horticulture.

  10. Defining pheromone-receptor signaling in Candida albicans and related asexual Candida species.

    Science.gov (United States)

    Lin, Ching-Hsuan; Choi, Anthony; Bennett, Richard J

    2011-12-01

    Candida albicans is an important human fungal pathogen in which sexual reproduction is under the control of the novel white-opaque switch. Opaque cells are the mating-competent form, whereas white cells do not mate but can still respond to pheromones, resulting in biofilm formation. In this study, we first define the domains of the α-pheromone receptor Ste2 that are necessary for signaling in both white and opaque forms. Both cell states require the IC loop 3 (IC3) and the C-terminal tail of Ste2 for the cellular response, whereas the first IC loop (IC1) of Ste2 is dispensable for signaling. To also address pheromone-receptor interactions in related species, including apparently asexual Candida species, Ste2 orthologues were heterologously expressed in Candida albicans. Ste2 receptors from multiple Candida clade species were functional when expressed in C. albicans, whereas the Ste2 receptor of Candida lusitaniae was nonfunctional. Significantly, however, expression of a chimeric C. lusitaniae Ste2 receptor containing the C-terminal tail of Ste2 from C. albicans generated a productive response to C. lusitaniae pheromone. This system has allowed us to characterize pheromones from multiple Candida species and indicates that functional pheromone-receptor couples exist in fungal species that have yet to be shown to undergo sexual mating.

  11. La identidad asexual: de la masculinización social a las redes sociales virtuales

    Directory of Open Access Journals (Sweden)

    Mª Teresa López Ruiz

    2015-01-01

    Full Text Available En el marco de una tesis doctoral a propósito de la aparición, en la escena social, de la nueva identidad asexual, el presente trabajo indaga en los principales factores socio-culturales que pueden haber incidido en su desarrollo. Una identidad que se elabora intersubjetivamente ante nuestros ojos en el seno de una comunidad virtual y a la que, por tanto, no le pueden ser ajenos factores como las posibilidades que ofrecen actualmente las tecnologías de la información y la comunicación. Las nuevas redes sociales comienzan así a mostrarse, no sólo como instrumentos útiles para impulsar algunos cambios en las políticas públicas, o no sólo como generadoras de nuevas formas de comunicación, conocimiento y saber, sino como espacios donde se elaboran y se transmiten cambios, incluso en los aspectos que parecerían más íntimos del ser humano, como la propia sexualidad, en cuya normatividad ha enraizado siempre el deber ser- esto es, la identidad- de mujeres y hombres.

  12. Changes in Plasmodium falciparum gametocytaemia in children with chloroquine-sensitive asexual infections

    Directory of Open Access Journals (Sweden)

    Sowunmi A.

    2003-12-01

    Full Text Available A non-compartmental pharmacokinetic model was used to describe the changes in gametocytaemia in nine children with chloroquine-sensitive Plasmodium falciparum malaria in whom asexual parasitaemia cleared within 72 h of chloroquine treatment. Peak gametocytaemia was 74 ± 19.9 (se, range 24-198, géométrie mean 58 sf (sexual forms/ul. Time to peak gametocytaemia was 43.2 ± 14.4, range 0-120 h. Following peak gametocytaemia, gametocytes persisted in blood for a period of 168-504 h. The décline from peak gametocytaemia was exponential with a half-life of gametocytaemia of 43.2 ± 20.4, range 1 3.1-206 h. The mean pre-treatment sex ratio was male-biased and remained so til! complete elimination of gametocytaemia. Peak microgametocytaemia, area under the curve of microgametocytaemia versus time, and the half-life of microgametocytaemia were significantly higher than those of macrogametocytaemia. The volume of blood completely cleared of macrogametocytaemia per unit time was significantly higher than that of microgametocytaemia. Macrogametocytes are cleared from the circulation faster than microgametocytes but chloroquine treatment of chloroquine-sensitive infections has little or no significant effect on gametocyte sex ratios in this group of children.

  13. Recombination in Glomus intraradices, a supposed ancient asexual arbuscular mycorrhizal fungus

    Directory of Open Access Journals (Sweden)

    Sanders Ian R

    2009-01-01

    Full Text Available Abstract Background Arbuscular mycorrhizal fungi (AMF are important symbionts of most plant species, promoting plant diversity and productivity. This symbiosis is thought to have contributed to the early colonisation of land by plants. Morphological stasis over 400 million years and the lack of an observed sexual stage in any member of the phylum Glomeromycota led to the controversial suggestion of AMF being ancients asexuals. Evidence for recombination in AMF is contradictory. Results We addressed the question of recombination in the AMF Glomus intraradices by sequencing 11 polymorphic nuclear loci in 40 morphologically identical isolates from one field. Phylogenetic relationships among genotypes showed a reticulate network pattern providing a rationale to test for recombination. Five statistical tests predicted multiple recombinant regions in the genome of a core set of isolates. In contrast, five clonal lineages had fixed a large number of differences. Conclusion Our data show that AMF from one field have undergone recombination but that clonal lineages coexist. This finding has important consequences for understanding AMF evolution, co-evolution of AMF and plants and highlights the potential for commercially introduced AMF inoculum recombining with existing local populations. Finally, our results reconcile seemingly contradictory studies on whether AMF are clonal or form recombining populations.

  14. Stem cell system in asexual and sexual reproduction of Enchytraeus japonensis (Oligochaeta, Annelida).

    Science.gov (United States)

    Yoshida-Noro, Chikako; Tochinai, Shin

    2010-01-01

    Enchytraeus japonensis is a small oligochaete species that proliferates asexually via fragmentation and regeneration. As sexual reproduction can also be induced, it is a good model system for the study of both regenerative and germline stem cells. It has been shown by histological study that putative mesodermal stem cells called neoblasts, and dedifferentiated epidermal and endodermal cells are involved in blastema formation. Recently, we isolated three region-specific marker genes expressed in the digestive tract and showed by in situ hybridization that morphallactic as well as epimorphic regulation of the body patterning occurs during regeneration. We also cloned two vasa-related genes and analyzed their expression during development and in mature worms that undergo sexual reproduction. The results arising form these studies suggest that the origin and development of germline stem cells and neoblasts may be independent. Furthermore, we carried out functional analysis using RNA interference (RNAi) and showed that a novel gene termed grimp is required for mesodermal cell proliferation at the initial stages of regeneration. These findings indicate that the stem cell system in E. japonensis is regulated by both internal and external environmental factors.

  15. Facultative asexual reproduction and genetic diversity of populations in the humivorous termite Cavitermes tuberosus.

    Science.gov (United States)

    Fournier, Denis; Hellemans, Simon; Hanus, Robert; Roisin, Yves

    2016-06-15

    Termite colonies are typically founded by a pair of sexually reproducing dispersers, which can sometimes be replaced by some of their offspring. Some Reticulitermes and Embiratermes species routinely practice asexual queen succession (AQS): the queen is replaced by neotenic daughters produced by parthenogenesis, which mate with the primary king. Here, to cast light on the evolution of AQS, we investigated another candidate species, Cavitermes tuberosus (Termitinae). Of 95 nests, 39 contained a primary queen and 28 contained neotenic females (2-667 individuals), usually with the primary king. Microsatellite analyses confirmed that colonies were initiated by single pairs after large dispersal flights. More than 80% of the neotenic females were of exclusively maternal origin and completely homozygous, suggesting automictic parthenogenesis with gamete duplication. Conversely, workers, soldiers, and most alates and primary reproductives were produced sexually. AQS often occurs late, after colonies have reached maturity, whereas early AQS in other species may boost the young colony's growth rate. We suggest additional benefits of AQS in C. tuberosus, related with a smaller size, lesser stability and higher mobility of colonies. Our data add to the phylogenetical dispersion and diversity of modalities of AQS in termites, supporting a multiple evolutionary origin of this process.

  16. Expression and function of myc during asexual reproduction of the budding ascidian Polyandrocarpa misakiensis.

    Science.gov (United States)

    Fujiwara, Shigeki; Isozaki, Takaomi; Mori, Kyoko; Kawamura, Kazuo

    2011-12-01

    The budding ascidian Polyandrocarpa misakiensis proliferates asexually by budding. The atrial epithelium is a multipotent but differentiated tissue, which transdifferentiates into various tissues and organs after the bud separates from the parental body. We isolated cDNA clones homologous to the myc proto-oncogene from P. misakiensis. The cDNA, named Pm-myc, encoded a polypeptide of 639 amino acid residues, containing Myc-specific functional motifs, Myc box I and Myc box II, and the basic helix-loop-helix domain. Expression of Pm-myc was observed in the atrial epithelium in the organ-forming region of the developing bud, where the epithelial cells dedifferentiate and re-enter the cell cycle. The expression was also observed in fibroblast-like cells, which are known to participate in the organogenesis together with the epithelial cells. Unexpectedly, the atrial epithelium expressed Pm-myc more than one day before the dedifferentiation. The organogenesis was disturbed by Pm-myc-specific double-stranded RNA. In situ hybridization revealed that Pm-myc-positive fibroblast-like cells disappeared around the organ primordium of the dsRNA-treated bud. The results suggest that the mesenchymal-epithelial transition of fibroblast-like cells is important for the organogenesis in this budding ascidian species.

  17. Asexual reproduction in a close relative of Arabidopsis: a genetic investigation of apomixis in Boechera (Brassicaceae).

    Science.gov (United States)

    Schranz, M Eric; Kantama, Laksana; de Jong, Hans; Mitchell-Olds, Thomas

    2006-01-01

    Understanding apomixis (asexual reproduction through seeds) is of great interest to both plant breeders and evolutionary biologists. The genus Boechera is an excellent system for studying apomixis because of its close relationship to Arabidopsis, the occurrence of apomixis at the diploid level, and its potentially simple inheritance by transmission of a heterochromatic (Het) chromosome. Diploid sexual Boechera stricta and diploid apomictic Boechera divaricarpa (carrying a Het chromosome) were crossed. Flow cytometry, karyotype analysis, genomic in situ hybridization, pollen staining and seed-production measurements were used to analyse the parents and resulting F1, F2 and selected F3 and test-cross (TC) generations. The F1 plant was a low-fertility triploid that produced a swarm of aneuploid and polyploid F2 progeny. Two of the F2 plants were fertile near-tetraploids, and analysis of their F3 and TC progeny revealed that they were sexual and genomically stabilized. The apomictic phenotype was not transmitted by genetic crossing as a single dominant locus on the Het chromosome, suggesting a complex genetic control of apomixis that has implications for future genetic and evolutionary analyses in this group.

  18. Mutualism and asexual reproduction influence recognition genes in a fungal symbiont.

    Science.gov (United States)

    van der Nest, Magriet A; Steenkamp, Emma T; Wilken, Markus P; Stenlid, Jan; Wingfield, Mike J; Wingfield, Brenda D; Slippers, Bernard

    2013-06-01

    Mutualism between microbes and insects is common and alignment of the reproductive interests of microbial symbionts with this lifestyle typically involves clonal reproduction and vertical transmission by insect partners. Here the Amylostereum fungus-Sirex woodwasp mutualism was used to consider whether their prolonged association and predominance of asexuality have affected the mating system of the fungal partner. Nucleotide information for the pheromone receptor gene rab1, as well as the translation elongation factor 1α gene and ribosomal RNA internal transcribed spacer region were utilized. The identification of rab1 alleles in Amylostereum chailletii and Amylostereum areolatum populations revealed that this gene is more polymorphic than the other two regions, although the diversity of all three regions was lower than what has been observed in free-living Agaricomycetes. Our data suggest that suppressed recombination might be implicated in the diversification of rab1, while no evidence of balancing selection was detected. We also detected positive selection at only two codons, suggesting that purifying selection is important for the evolution of rab1. The symbiotic relationship with their insect partners has therefore influenced the diversity of this gene and influenced the manner in which selection drives and maintains this diversity in A. areolatum and A. chailletii.

  19. Boxer crabs induce asexual reproduction of their associated sea anemones by splitting and intraspecific theft

    Directory of Open Access Journals (Sweden)

    Yisrael Schnytzer

    2017-01-01

    Full Text Available Crabs of the genus Lybia have the remarkable habit of holding a sea anemone in each of their claws. This partnership appears to be obligate, at least on the part of the crab. The present study focuses on Lybia leptochelis from the Red Sea holding anemones of the genus Alicia (family Aliciidae. These anemones have not been found free living, only in association with L. leptochelis. In an attempt to understand how the crabs acquire them, we conducted a series of behavioral experiments and molecular analyses. Laboratory observations showed that the removal of one anemone from a crab induces a “splitting” behavior, whereby the crab tears the remaining anemone into two similar parts, resulting in a complete anemone in each claw after regeneration. Furthermore, when two crabs, one holding anemones and one lacking them, are confronted, the crabs fight, almost always leading to the “theft” of a complete anemone or anemone fragment by the crab without them. Following this, crabs “split” their lone anemone into two. Individuals of Alicia sp. removed from freshly collected L. leptochelis were used for DNA analysis. By employing AFLP (Fluorescence Amplified Fragments Length Polymorphism it was shown that each pair of anemones from a given crab is genetically identical. Furthermore, there is genetic identity between most pairs of anemone held by different crabs, with the others showing slight genetic differences. This is a unique case in which one animal induces asexual reproduction of another, consequently also affecting its genetic diversity.

  20. Boxer crabs induce asexual reproduction of their associated sea anemones by splitting and intraspecific theft.

    Science.gov (United States)

    Schnytzer, Yisrael; Giman, Yaniv; Karplus, Ilan; Achituv, Yair

    2017-01-01

    Crabs of the genus Lybia have the remarkable habit of holding a sea anemone in each of their claws. This partnership appears to be obligate, at least on the part of the crab. The present study focuses on Lybia leptochelis from the Red Sea holding anemones of the genus Alicia (family Aliciidae). These anemones have not been found free living, only in association with L. leptochelis. In an attempt to understand how the crabs acquire them, we conducted a series of behavioral experiments and molecular analyses. Laboratory observations showed that the removal of one anemone from a crab induces a "splitting" behavior, whereby the crab tears the remaining anemone into two similar parts, resulting in a complete anemone in each claw after regeneration. Furthermore, when two crabs, one holding anemones and one lacking them, are confronted, the crabs fight, almost always leading to the "theft" of a complete anemone or anemone fragment by the crab without them. Following this, crabs "split" their lone anemone into two. Individuals of Alicia sp. removed from freshly collected L. leptochelis were used for DNA analysis. By employing AFLP (Fluorescence Amplified Fragments Length Polymorphism) it was shown that each pair of anemones from a given crab is genetically identical. Furthermore, there is genetic identity between most pairs of anemone held by different crabs, with the others showing slight genetic differences. This is a unique case in which one animal induces asexual reproduction of another, consequently also affecting its genetic diversity.

  1. Getting CSR communication fit

    DEFF Research Database (Denmark)

    Schmeltz, Line

    2017-01-01

    Companies experience increasing legal and societal pressure to communicate about their corporate social responsibility (CSR) engagements from a number of different publics. One very important group is that of young consumers who are predicted to be the most important and influential consumer group...... in the near future. From a value- theoretical base, this article empirically explores the role and applicability of ‘fit’ in strategic CSR communication targeted at young consumers. Point of departure is taken in the well-known strategic fit (a logical link between a company’s CSR commitment and its core...... values) and is further developed by introducing two additional fits, the CSR- Consumer fit and the CSR-Consumer-Company fit (Triple Fit). Through a sequential design, the three fits are empirically tested and their potential for meeting young consumers’ expectations for corporate CSR messaging...

  2. Improving NEC Fit

    Science.gov (United States)

    2015-09-01

    Fill cannot. NEC Fit NEC Fit measures more than the crew’s total skill sets. It also accounts for how these sailors are used by crediting an NEC...Abstract Navy enlisted classifications (NECs) denote special skills beyond those associated with a rating. They are used in defining manpower...requirements and in managing personnel by tracking sailors who have acquired these skills . NEC Fit is one of two primary metrics that Navy leadership

  3. Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei).

    Science.gov (United States)

    Majtánová, Zuzana; Choleva, Lukáš; Symonová, Radka; Ráb, Petr; Kotusz, Jan; Pekárik, Ladislav; Janko, Karel

    2016-01-01

    Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction.

  4. The universal Higgs fit

    DEFF Research Database (Denmark)

    Giardino, P. P.; Kannike, K.; Masina, I.

    2014-01-01

    Higgs models, models with extra Higgs doublets, supersymmetry, extra particles in the loops, anomalous top couplings, and invisible Higgs decays into Dark Matter. Best fit regions lie around the Standard Model predictions and are well approximated by our 'universal' fit. Latest data exclude the dilaton...

  5. Fit 2-B FATHERS.

    Science.gov (United States)

    Maiorano, Joseph J.

    2001-01-01

    Fit 2-B FATHERS is a parenting-skills education program for incarcerated adult males. The goals of this program are for participants to have reduced recidivism rates and a reduced risk of their children acquiring criminal records. These goals are accomplished by helping participants become physically, practically, and socially fit for the demands…

  6. Best Fit for 'Bounce'

    Science.gov (United States)

    2004-01-01

    The mineralogy of 'Bounce' rock was determined by fitting spectra from a library of laboratory minerals to the spectrum of Bounce taken by the Mars Exploration Rover Opportunity's miniature thermal emission spectrometer. The minerals that give the best fit include pyroxene, plagioclase and olivine -- minerals commonly found in basaltic volcanic rocks -- and typical martian dust produced by the rover's rock abrasion tool.

  7. Fitness Test and Tips

    Institute of Scientific and Technical Information of China (English)

    Karen; Clark

    2005-01-01

    Summer is a time to exercise and keep fit.Ask yourself these quick questions and check your score below.How fit are you? 1.What is your pulse[脉搏]?Find your pulse in your wrist[手腕], count the number of beats[跳动] in one minute,Now

  8. The Quality Fit.

    Science.gov (United States)

    Vertiz, Virginia C.; Downey, Carolyn J.

    This paper proposes a two-pronged approach for examining an educational program's "quality of fit." The American Association of School Administrators' (AASA's) Curriculum Management Audit for quality indicators is reviewed, using the Downey Quality Fit Framework and Deming's 4 areas of profound knowledge and 14 points. The purpose is to…

  9. Mn(II) oxidation by an ascomycete fungus is linked to superoxide production during asexual reproduction

    Energy Technology Data Exchange (ETDEWEB)

    Hansel, C. M.; Zeiner, C. A.; Santelli, C. M.; Webb, S. M.

    2012-07-16

    Manganese (Mn) oxides are among the most reactive minerals within the environment, where they control the bioavailability of carbon, nutrients, and numerous metals. Although the ability of microorganisms to oxidize Mn(II) to Mn(III/IV) oxides is scattered throughout the bacterial and fungal domains of life, the mechanism and physiological basis for Mn(II) oxidation remains an enigma. Here, we use a combination of compound-specific chemical assays, microspectroscopy, and electron microscopy to show that a common Ascomycete filamentous fungus, Stilbella aciculosa, oxidizes Mn(II) to Mn oxides by producing extracellular superoxide during cell differentiation. The reactive Mn oxide phase birnessite and the reactive oxygen species superoxide and hydrogen peroxide are colocalized at the base of asexual reproductive structures. Mn oxide formation is not observed in the presence of superoxide scavengers (e.g., Cu) and inhibitors of NADPH oxidases (e.g., diphenylene iodonium chloride), enzymes responsible for superoxide production and cell differentiation in fungi. Considering the recent identification of Mn(II) oxidation by NADH oxidase-based superoxide production by a common marine bacterium (Roseobacter sp.), these results introduce a surprising homology between some prokaryotic and eukaryotic organisms in the mechanisms responsible for Mn(II) oxidation, where oxidation appears to be a side reaction of extracellular superoxide production. Finally, given the versatility of superoxide as a redox reactant and the widespread ability of fungi to produce superoxide, this microbial extracellular superoxide production may play a central role in the cycling and bioavailability of metals (e.g., Hg, Fe, Mn) and carbon in natural systems.

  10. An anatomical description of a miniaturized acorn worm (hemichordata, enteropneusta) with asexual reproduction by paratomy.

    Science.gov (United States)

    Worsaae, Katrine; Sterrer, Wolfgang; Kaul-Strehlow, Sabrina; Hay-Schmidt, Anders; Giribet, Gonzalo

    2012-01-01

    The interstitial environment of marine sandy bottoms is a nutrient-rich, sheltered habitat whilst at the same time also often a turbulent, space-limited, and ecologically challenging environment dominated by meiofauna. The interstitial fauna is one of the most diverse on earth and accommodates miniaturized representatives from many macrofaunal groups as well as several exclusively meiofaunal phyla. The colonization process of this environment, with the restrictions imposed by limited space and low Reynolds numbers, has selected for great morphological and behavioral changes as well as new life history strategies.Here we describe a new enteropneust species inhabiting the interstices among sand grains in shallow tropical waters of the West Atlantic. With a maximum body length of 0.6 mm, it is the first microscopic adult enteropneust known, a group otherwise ranging from 2 cm to 250 cm in adult size. Asexual reproduction by paratomy has been observed in this new species, a reproductive mode not previously reported among enteropneusts. Morphologically, Meioglossus psammophilus gen. et sp. nov. shows closest resemblance to an early juvenile stage of the acorn worm family Harrimaniidae, a result congruent with its phylogenetic placement based on molecular data. Its position, clearly nested within the larger macrofaunal hemichordates, suggests that this represents an extreme case of miniaturization. The evolutionary pathway to this simple or juvenile appearance, as chiefly demonstrated by its small size, dense ciliation, and single pair of gill pores, may be explained by progenesis. The finding of M. psammophilus gen. et sp. nov. underscores the notion that meiofauna may constitute a rich source of undiscovered metazoan diversity, possibly disguised as juveniles of other species.

  11. Mn(II) oxidation by an ascomycete fungus is linked to superoxide production during asexual reproduction.

    Science.gov (United States)

    Hansel, Colleen M; Zeiner, Carolyn A; Santelli, Cara M; Webb, Samuel M

    2012-07-31

    Manganese (Mn) oxides are among the most reactive minerals within the environment, where they control the bioavailability of carbon, nutrients, and numerous metals. Although the ability of microorganisms to oxidize Mn(II) to Mn(III/IV) oxides is scattered throughout the bacterial and fungal domains of life, the mechanism and physiological basis for Mn(II) oxidation remains an enigma. Here, we use a combination of compound-specific chemical assays, microspectroscopy, and electron microscopy to show that a common Ascomycete filamentous fungus, Stilbella aciculosa, oxidizes Mn(II) to Mn oxides by producing extracellular superoxide during cell differentiation. The reactive Mn oxide phase birnessite and the reactive oxygen species superoxide and hydrogen peroxide are colocalized at the base of asexual reproductive structures. Mn oxide formation is not observed in the presence of superoxide scavengers (e.g., Cu) and inhibitors of NADPH oxidases (e.g., diphenylene iodonium chloride), enzymes responsible for superoxide production and cell differentiation in fungi. Considering the recent identification of Mn(II) oxidation by NADH oxidase-based superoxide production by a common marine bacterium (Roseobacter sp.), these results introduce a surprising homology between some prokaryotic and eukaryotic organisms in the mechanisms responsible for Mn(II) oxidation, where oxidation appears to be a side reaction of extracellular superoxide production. Given the versatility of superoxide as a redox reactant and the widespread ability of fungi to produce superoxide, this microbial extracellular superoxide production may play a central role in the cycling and bioavailability of metals (e.g., Hg, Fe, Mn) and carbon in natural systems.

  12. Asexual endophytes in a native grass: tradeoffs in mortality, growth, reproduction, and alkaloid production.

    Science.gov (United States)

    Faeth, Stanley H; Hayes, Cinnamon J; Gardner, Dale R

    2010-10-01

    Neotyphodium endophytes are asexual, seed-borne fungal symbionts that are thought to interact mutualistically with their grass hosts. Benefits include increased growth, reproduction, and resistance to herbivores via endophytic alkaloids. Although these benefits are well established in infected introduced, agronomic grasses, little is known about the cost and benefits of endophyte infection in native grass populations. These populations exist as mosaics of uninfected and infected plants, with the latter often comprised of plants that vary widely in alkaloid content. We tested the costs and benefits of endophyte infections with varying alkaloids in the native grass Achnatherum robustum (sleepygrass). We conducted a 4-year field experiment, where herbivory and water availability were controlled and survival, growth, and reproduction of three maternal plant genotypes [uninfected plants (E-), infected plants with high levels of ergot alkaloids (E+A+), and infected plants with no alkaloids (E+A-)] were monitored over three growing seasons. Generally, E+A+ plants had reduced growth over the three growing seasons and lower seed production than E- or E+A- plants, suggesting a cost of alkaloid production. The reduction in vegetative biomass in E+A+ plants was most pronounced under supplemented water, contrary to the prediction that additional resources would offset the cost of alkaloid production. Also, E+A+ plants showed no advantage in growth, seed production, or reproductive effort under full herbivory relative to E- or E+A- grasses, contrary to the predictions of the defensive mutualism hypothesis. However, E+A+ plants had higher overwintering survival than E+A- plants in early plant ontogeny, suggesting that alkaloids associated with infection may protect against below ground herbivory or harsh winter conditions. Our results suggest that the mosaic of E-, E+A+, and E+A- plants observed in nature may result from varying biotic and abiotic selective factors that maintain

  13. Stem cells in asexual reproduction of Enchytraeus japonensis (Oligochaeta, Annelid): proliferation and migration of neoblasts.

    Science.gov (United States)

    Sugio, Mutsumi; Yoshida-Noro, Chikako; Ozawa, Kaname; Tochinai, Shin

    2012-05-01

    Enchytraeus japonensis is a small oligochaete that reproduces mainly asexually by fragmentation (autotomy) and regeneration. As sexual reproduction can also be induced, it is a good animal model for the study of both somatic and germline stem cells. To clarify the features of stem cells in regeneration, we investigated the proliferation and lineage of stem cells in E. japonensis. Neoblasts, which have the morphological characteristics of undifferentiated cells, were found to firmly adhere to the posterior surface of septa in each trunk segment. Also, smaller neoblast-like cells, which are designated as N-cells in this study, were located dorsal to the neoblasts on the septa. By conducting 5-bromo-2'-deoxyuridine (BrdU)-labeling-experiments, we have shown that neoblasts are slow-cycling (or quiescent) in intact growing worms, but proliferate rapidly in response to fragmentation. N-cells proliferate more actively than do neoblasts in intact worms. The results of pulse-chase experiments indicated that neoblast and N-cell lineage mesodermal cells that incorporated BrdU early in regeneration migrated toward the autotomized site to form the mesodermal region of the blastema, while the epidermal and intestinal cells also contributed to the blastema locally near the autotomized site. We have also shown that neoblasts have stem cell characteristics by expressing Ej-vlg2 and by the activity of telomerase during regeneration. Telomerase activity was high in the early stage of regeneration and correlated with the proliferation activity in the neoblast lineage of mesodermal stem cells. Taken together, our results indicate that neoblasts are mesodermal stem cells involved in the regeneration of E. japonensis.

  14. The planarian P2X homolog in the regulation of asexual reproduction.

    Science.gov (United States)

    Sakurai, Toshihide; Lee, Hayoung; Kashima, Makoto; Saito, Yumi; Hayashi, Tetsutaro; Kudome-Takamatsu, Tomomi; Nishimura, Osamu; Agata, Kiyokazu; Shibata, Norito

    2012-01-01

    The growth in size of freshwater planarians in response to nutrient intake is limited by the eventual separation of tail and body fragments in a process called fission. The resulting tail fragment regenerates the entire body as an artificially amputated tail fragment would do, and the body fragment regenerates a tail, resulting in two whole planarians. This regenerative ability is supported by pluripotent somatic stem cells, called neoblasts, which are distributed throughout almost the entire body of the planarian. Neoblasts are the only planarian cells with the ability to continuously proliferate and give rise to all types of cells during regeneration, asexual reproduction, homeostasis, and growth. In order to investigate the molecular characteristics of neoblasts, we conducted an extensive search for neoblast-specific genes using the High Coverage Expression Profiling (HiCEP) method, and tested the function of the resulting candidates by RNAi. Disruption of the expression of one candidate gene, DjP2X-A (Dugesia japonica membrane protein P2X homologue), resulted in a unique phenotype. DjP2X-A RNAi leads to an increase of fission events upon feeding. We confirmed by immunohistochemistry that DjP2X-A is a membrane protein, and elucidated its role in regulating neoblast proliferation, thereby explaining its unique phenotype. We found that DjP2X-A decreases the burst of neoblast proliferation that normally occurs after feeding. We also found that DjP2X-A is required for normal proliferation in starved animals. We propose that DjP2X-A modulates stem cell proliferation in response to the nutritional condition.

  15. Truncation of LEAFY COTYLEDON1 protein is required for asexual reproduction in Kalanchoë daigremontiana.

    Science.gov (United States)

    Garcês, Helena M P; Koenig, Daniel; Townsley, Brad T; Kim, Minsung; Sinha, Neelima R

    2014-05-01

    Kalanchoë daigremontiana reproduces asexually by generating numerous plantlets on its leaf margins. The formation of plantlets requires the somatic initiation of organogenic and embryogenic developmental programs in the leaves. However, unlike normal embryogenesis in seeds, leaf somatic embryogenesis bypasses seed dormancy to form viable plantlets. In Arabidopsis (Arabidopsis thaliana), seed dormancy and embryogenesis are initiated by the transcription factor LEAFY COTYLEDON1 (LEC1). The K. daigremontiana ortholog of LEC1 is expressed during leaf somatic embryo development. However, KdLEC1 encodes for a LEC1-type protein that has a unique B domain, with 11 unique amino acids and a premature stop codon. Moreover, the truncated KdLEC1 protein is not functional in Arabidopsis. Here, we show that K. daigremontiana transgenic plants expressing a functional, chimeric KdLEC1 gene under the control of Arabidopsis LEC1 promoter caused several developmental defects to leaf somatic embryos, including seed dormancy characteristics. The dormant plantlets also behaved as typical dormant seeds. Transgenic plantlets accumulated oil bodies and responded to the abscisic acid biosynthesis inhibitor fluridone, which broke somatic-embryo dormancy and promoted their normal development. Our results indicate that having a mutated form of LEC1 gene in K. daigremontiana is essential to bypass dormancy in the leaf embryos and generate viable plantlets, suggesting that the loss of a functional LEC1 promotes viviparous leaf somatic embryos and thus enhances vegetative propagation in K. daigremontiana. Mutations resulting in truncated LEC1 proteins may have been of a selective advantage in creating somatic propagules, because such mutations occurred independently in several Kalanchoë species, which form plantlets constitutively.

  16. Limitations of inclusive fitness.

    Science.gov (United States)

    Allen, Benjamin; Nowak, Martin A; Wilson, Edward O

    2013-12-10

    Until recently, inclusive fitness has been widely accepted as a general method to explain the evolution of social behavior. Affirming and expanding earlier criticism, we demonstrate that inclusive fitness is instead a limited concept, which exists only for a small subset of evolutionary processes. Inclusive fitness assumes that personal fitness is the sum of additive components caused by individual actions. This assumption does not hold for the majority of evolutionary processes or scenarios. To sidestep this limitation, inclusive fitness theorists have proposed a method using linear regression. On the basis of this method, it is claimed that inclusive fitness theory (i) predicts the direction of allele frequency changes, (ii) reveals the reasons for these changes, (iii) is as general as natural selection, and (iv) provides a universal design principle for evolution. In this paper we evaluate these claims, and show that all of them are unfounded. If the objective is to analyze whether mutations that modify social behavior are favored or opposed by natural selection, then no aspect of inclusive fitness theory is needed.

  17. Comparison of three replication strategies in complex multicellular organisms: Asexual replication, sexual replication with identical gametes, and sexual replication with distinct sperm and egg gametes

    Science.gov (United States)

    Tannenbaum, Emmanuel

    2008-01-01

    This paper studies the mutation-selection balance in three simplified replication models. The first model considers a population of organisms replicating via the production of asexual spores. The second model considers a sexually replicating population that produces identical gametes. The third model considers a sexually replicating population that produces distinct sperm and egg gametes. All models assume diploid organisms whose genomes consist of two chromosomes, each of which is taken to be functional if equal to some master sequence, and defective otherwise. In the asexual population, the asexual diploid spores develop directly into adult organisms. In the sexual populations, the haploid gametes enter a haploid pool, where they may fuse with other haploids. The resulting immature diploid organisms then proceed to develop into mature organisms. Based on an analysis of all three models, we find that, as organism size increases, a sexually replicating population can only outcompete an asexually replicating population if the adult organisms produce distinct sperm and egg gametes. A sexual replication strategy that is based on the production of large numbers of sperm cells to fertilize a small number of eggs is found to be necessary in order to maintain a sufficiently low cost for sex for the strategy to be selected for over a purely asexual strategy. We discuss the usefulness of this model in understanding the evolution and maintenance of sexual replication as the preferred replication strategy in complex, multicellular organisms.

  18. BIBLIOMETRICS ON ONE OF THE LARGEST TERMITE INVENTORIES IN THE CERRADO: "STUDIES ON TERMITES FROM THE MATO GROSSO STATE, BRAZIL BY AGA MATHEWS 1977"

    Directory of Open Access Journals (Sweden)

    HÉLIDA FERREIRA DA CUNHA

    2015-01-01

    Full Text Available ABSTRACT This paper consists on a bibliometric analysis of the international influences of the book "Studies on termites from the Mato Grosso State, Brazil", by AGA Mathews (1977. The number of citations has increased over the years after the first citation. Mathews book was cited in articles, reviews, theses, dissertations, books, book chapters, abstracts in conference proceedings, comments and scientific notes. Most these studies are empirical and descriptive. The studies were conducted in 35 countries of the Neotropical, Palearctic, Afrotropical, Nearctic, Australasia and Indomalaya regions. 55% of the studies were carried out in Brazil. The journals Sociobiology and Insectes Sociaux, have social insect studies within its scope, and the highest number of articles citing Mathews. Most of the 71 authors that cited Mathews more than twice are Brazilian. Constrictotermes cyphergaster was the most studied in over 80% of the studies addressing Isoptera. The most frequent keywords were termite, Isoptera and taxonomy, generalist terms indexed in most publications carried out in different countries. Most of the research studies were carried out in laboratories and native vegetation areas. Studies in agroecosystems were implemented predominantly in Brazil. This study shows the diversity of application (citations of Mathews' book, and that the number of citations will continue to increase due to the large amount of information presented by the author.

  19. The Role of Aga Khan Rural Support Programme in Rural Development in the Karakorum, Hindu Kush & Himalayan Region: Examples from the Northern Mountainous Belt of Pakistan

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Pakistan is predominantly a mountainous country where rural development activities are characterised by inconsistency, politically motivated short-term projects without proper feedback. Since the inception of the country, the top-down approach has been followed, and the same development plans that were formulated for the plain areas have been extended to the mountains without any modification.In doing so, neither the participation of the local communities was cared for, nor the mountain specificities were considered in the planning process.Moreover, the representation of the local inhabitants was improper and contradictory to the facts. This biased approach has been one of the main causes for the failure of development projects carried out by different agencies of the Government. Contrary to the perception of the state authorities, the mountain communities proved to be more open to accept new approaches and demonstrated the capacity and capability of being a dependable development partner.In this paper, a detailed account of the Aga Khan Rural Support Programme (AKRSP) has been presented to assess and evaluate the approach followed by this non-governmental organisation (NGO), and the response of the local inhabitants as collaborators in the development process. The achievements of the AKRSP from project planning,implementation and monitoring can be adopted as a model for rural development not only in the plains,but also in the mountainous areas of the developing countries in the world.

  20. 雄激素源性脱发的中医治疗进展%TCM Treatment Developments to Androgenetic Alopecia(AGA)

    Institute of Scientific and Technical Information of China (English)

    任芳; 魏跃钢

    2012-01-01

    AGA is the most common alopecia in clinic, showing gradual alopecia with thinner hairs on forehead and front top of the head, then to the top head, belonging to the androgen-depending autosome dominant heredity polytrope disease. TCM has advantages on it. The article sums up the treatment of the disease in recent years on therapy based on differentiation, special formula, outer therapy and acupuncture, etc.%雄激素源性脱发是临床上最常见的脱发类型,表现为前额及前顶部的毛发稀疏变细的渐进性脱发,继而形成高额,为雄激素依赖的常染色体显性遗传性多变性疾病,中医药治疗有明显的优势.本文分别从其辩证论治、经验专方、外治法、针灸疗法等方面就近年来的治疗进展加以综述.

  1. The putative protein methyltransferase LAE1 of Trichoderma atroviride is a key regulator of asexual development and mycoparasitism.

    Directory of Open Access Journals (Sweden)

    Razieh Karimi Aghcheh

    Full Text Available In Ascomycota the protein methyltransferase LaeA is a global regulator that affects the expression of secondary metabolite gene clusters, and controls sexual and asexual development. The common mycoparasitic fungus Trichoderma atroviride is one of the most widely studied agents of biological control of plant-pathogenic fungi that also serves as a model for the research on regulation of asexual sporulation (conidiation by environmental stimuli such as light and/or mechanical injury. In order to learn the possible involvement of LAE1 in these two traits, we assessed the effect of deletion and overexpression of lae1 gene on conidiation and mycoparasitic interaction. In the presence of light, conidiation was 50% decreased in a Δ lae1 and 30-50% increased in lae1-overexpressing (OElae1 strains. In darkness, Δ lae1 strains did not sporulate, and the OElae1 strains produced as much spores as the parent strain. Loss-of-function of lae1 also abolished sporulation triggered by mechanical injury of the mycelia. Deletion of lae1 also increased the sensitivity of T. atroviride to oxidative stress, abolished its ability to defend against other fungi and led to a loss of mycoparasitic behaviour, whereas the OElae1 strains displayed enhanced mycoparasitic vigor. The loss of mycoparasitic activity in the Δ lae1 strain correlated with a significant underexpressionn of several genes normally upregulated during mycoparasitic interaction (proteases, GH16 ß-glucanases, polyketide synthases and small cystein-rich secreted proteins, which in turn was reflected in the partial reduction of formation of fungicidal water soluble metabolites and volatile compounds. Our study shows T. atroviride LAE1 is essential for asexual reproduction in the dark and for defense and parasitism on other fungi.

  2. Resilience of Zostera muelleri seagrass to small-scale disturbances: the relative importance of asexual versus sexual recovery.

    Science.gov (United States)

    Macreadie, Peter I; York, Paul H; Sherman, Craig Dh

    2014-02-01

    Resilience is the ability of an ecosystem to recover from disturbance without loss of essential function. Seagrass ecosystems are key marine and estuarine habitats that are under threat from a variety of natural and anthropogenic disturbances. The ability of these ecosystems to recovery from disturbance will to a large extent depend on the internsity and scale of the disturbance, and the relative importance of sexual versus asexual reproduction within populations. Here, we investigated the resilience of Zostera muelleri seagrass (Syn. Zostera capricorni) to small-scale disturbances at four locations in Lake Macquarie - Australia's largest coastal lake - and monitored recovery over a 65-week period. Resilience of Z. muelleri varied significantly with disturbance intensity; Z. muelleri recovered rapidly (within 2 weeks) from low-intensity disturbance (shoot loss), and rates of recovery appeared related to initial shoot length. Recovery via rhizome encroachment (asexual regeneration) from high-intensity disturbance (loss of entire plant) varied among locations, ranging from 18-35 weeks, whereas the ability to recover was apparently lost (at least within the time frame of this study) when recovery depended on sexual regeneration, suggesting that seeds do not provide a mechanism of recovery against intense small-scale disturbances. The lack of sexual recruits into disturbed sites is surprising as our initial surveys of genotypic diversity (using nine polymorphic microsatellite loci) at these location indicate that populations are maintained by a mix of sexual and asexual reproduction (genotypic diversity [R] varied from 0.24 to 0.44), and populations consisted of a mosaic of genotypes with on average 3.6 unique multilocus genotypes per 300 mm diameter plot. We therefore conclude that Z. muelleri populations within Lake Macquarie rely on clonal growth to recover from small-scale disturbances and that ongoing sexual recruitment by seeds into established seagrass beds

  3. ACSM Fit Society Page

    Science.gov (United States)

    ... 2011 -- Exercise for Special Populations 2011 -- Behavior Change & Exercise Adherence 2011 -- Nutrition 2011 -- Winter Health 2010 -- Healthy Aging 2010 -- Weight Loss & Weight Management 2010 -- Fitness Assessment & Injury Prevention 2009 -- Strength Training 2009 -- Menopause ...

  4. Getting Fit Before Pregnancy

    Science.gov (United States)

    ... Global Map Premature birth report card Careers Archives Pregnancy Before or between pregnancies Nutrition, weight & fitness Prenatal ... virus and pregnancy Folic acid Medicine safety and pregnancy Birth defects prevention Learn how to help reduce ...

  5. Fitting Galaxies on GPUs

    Science.gov (United States)

    Barsdell, B. R.; Barnes, D. G.; Fluke, C. J.

    2011-07-01

    Structural parameters are normally extracted from observed galaxies by fitting analytic light profiles to the observations. Obtaining accurate fits to high-resolution images is a computationally expensive task, requiring many model evaluations and convolutions with the imaging point spread function. While these algorithms contain high degrees of parallelism, current implementations do not exploit this property. With ever-growing volumes of observational data, an inability to make use of advances in computing power can act as a constraint on scientific outcomes. This is the motivation behind our work, which aims to implement the model-fitting procedure on a graphics processing unit (GPU). We begin by analysing the algorithms involved in model evaluation with respect to their suitability for modern many-core computing architectures like GPUs, finding them to be well-placed to take advantage of the high memory bandwidth offered by this hardware. Following our analysis, we briefly describe a preliminary implementation of the model fitting procedure using freely-available GPU libraries. Early results suggest a speed-up of around 10× over a CPU implementation. We discuss the opportunities such a speed-up could provide, including the ability to use more computationally expensive but better-performing fitting routines to increase the quality and robustness of fits.

  6. Cryptic fitness advantage: diploids invade haploid populations despite lacking any apparent advantage as measured by standard fitness assays.

    Directory of Open Access Journals (Sweden)

    Aleeza C Gerstein

    Full Text Available Ploidy varies tremendously within and between species, yet the factors that influence when or why ploidy variants are adaptive remains poorly understood. Our previous work found that diploid individuals repeatedly arose within ten replicate haploid populations of Saccharomyces cerevisiae, and in each case we witnessed diploid takeover within ~1800 asexual generations of batch culture evolution in the lab. The character that allowed diploids to rise in frequency within haploid populations remains unknown. Here we present a number of experiments conducted with the goal to determine what this trait (or traits might have been. Experiments were conducted both by sampling a small number of colonies from the stocks frozen every two weeks (~ 93 generations during the original experiment, as well through sampling a larger number of colonies at the two time points where polymorphism for ploidy was most prevalent. Surprisingly, none of our fitness component measures (lag phase, growth rate, biomass production indicated an advantage to diploidy. Similarly, competition assays against a common competitor and direct competition between haploid and diploid colonies isolated from the same time point failed to indicate a diploid advantage. Furthermore, we uncovered a tremendous amount of trait variation among colonies of the same ploidy level. Only late-appearing diploids showed a competitive advantage over haploids, indicating that the fitness advantage that allowed eventual takeover was not diploidy per se but an attribute of a subset of diploid lineages. Nevertheless, the initial rise in diploids to intermediate frequency cannot be explained by any of the fitness measures used; we suggest that the resolution to this mystery is negative frequency-dependent selection, which is ignored in the standard fitness measures used.

  7. Sex in an uncertain world: environmental stochasticity helps restore competitive balance between sexually and asexually reproducing populations.

    Science.gov (United States)

    Park, A W; Vandekerkhove, J; Michalakis, Y

    2014-08-01

    Like many organisms, individuals of the freshwater ostracod species Eucypris virens exhibit either obligate sexual or asexual reproductive modes. Both types of individual routinely co-occur, including in the same temporary freshwater pond (their natural habitat in which they undergo seasonal diapause). Given the well-known two-fold cost of sex, this begs the question of how sexually reproducing individuals are able to coexist with their asexual counterparts in spite of such overwhelming costs. Environmental stochasticity in the form of 'false dawn' inundations (where the first hydration is ephemeral and causes loss of early hatching individuals) may provide an advantage to the sexual subpopulation, which shows greater variation in hatching times following inundation. We explore the potential role of environmental stochasticity in this system using life-history data analysis, climate data, and matrix projection models. In the absence of environmental stochasticity, the population growth rate is significantly lower in sexual subpopulations. Climate data reveal that 'false dawn' inundations are common. Using matrix projection modelling with and without environmental stochasticity, we demonstrate that this phenomenon can restore appreciable balance to the system, in terms of population growth rates. This provides support for the role of environmental stochasticity in helping to explain the maintenance of sex and the occurrence of geographical parthenogenesis. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  8. Polymorphism and methylation patterns in Agave tequilana Weber var. 'Azul' plants propagated asexually by three different methods.

    Science.gov (United States)

    Díaz-Martínez, Miriam; Nava-Cedillo, Alejandro; Guzmán-López, José Alfredo; Escobar-Guzmán, Rocío; Simpson, June

    2012-04-01

    Genetic variation in three forms of asexually propagated Agave tequilana Weber var. 'Azul' plants namely offsets, bulbils and in vitro cultured individuals was studied by AFLP analysis. Low levels of variation were observed between mother plants and offsets and a higher level between mother plant and bulbils. Families obtained from commercial plantations showed lower levels of variation in comparison to families grown as ornamentals. No variation was observed between the original explant and four generations of in vitro cultured plants. Epigenetic variation was also studied by analyzing changes in methylation patterns between mother plants and offspring in each form of asexual reproduction. Offsets and bulbils showed an overall decrease in methylation whereas in vitro cultured plants showed patterns specific to each generation: Generations 1 and 4 showed overall demethylation whereas Generations 2 and 3 showed increased methylation. Analysis of ESTs associated with transposable elements revealed higher proportions of ESTs from Ty1-copia-like, Gypsy and CACTA transposable elements in cDNA libraries obtained from pluripotent tissue suggesting a possible correlation between methylation patterns, expression of transposable element associated genes and somaclonal variation.

  9. Size Matters!. Birth Size and a Size-Independent Stochastic Term Determine Asexual Reproduction Dynamics in Freshwater Planarians

    Science.gov (United States)

    Thomas, Michael A.; Quinodoz, Sofia; Schötz, Eva-Maria

    2012-09-01

    Asexual reproduction by division in higher organisms is rare, because a prerequisite is the ability to regenerate an entire organism from a piece of the original body. Freshwater planarians are one of the few animals that can reproduce this way, but little is known about the regulation of their reproduction cycles or strategies. We have previously shown that a planarian's reproduction strategy is randomized to include fragmentations, producing multiple offspring, as well as binary fissions, and can be partially explained by a maximum relative entropy principle. In this study we attempt to decompose the factors controlling their reproduction cycle. Based on recent studies on the cell cycle of budding yeast, which suggest that molecular noise in gene expression and cell size at birth together control cell cycle variability, we investigated whether the variability in planarian reproduction waiting times could be similarly regulated. We find that such a model can indeed explain the observed distribution of waiting times between birth and next reproductive event, suggesting that birth size and a stochastic noise term govern the reproduction dynamics of asexual planarians.

  10. Comparative transcriptional analysis of asexual and sexual morphs reveals possible mechanisms in reproductive polyphenism of the cotton aphid.

    Directory of Open Access Journals (Sweden)

    Li-Jun Liu

    Full Text Available Aphids, the destructive insect pests in the agriculture, horticulture and forestry, are capable of reproducing asexually and sexually upon environmental change. However, the molecular basis of aphid reproductive mode switch remains an enigma. Here we report a comparative analysis of differential gene expression profiling among parthenogenetic females, gynoparae and sexual females of the cotton aphid Aphis gossypii, using the RNA-seq approach with next-generation sequencing platforms, followed by RT-qPCR. At the cutoff criteria of fold change ≥2 and P<0.01, we identified 741 up- and 879 down-regulated genes in gynoparae versus parthenogenetic females, 2,101 up- and 2,210 down-regulated genes in sexual females compared to gynoparae, and 1,614 up- and 2,238 down-regulated genes in sexual females relative to parthenogenetic females. Gene ontology category and KEGG pathway analysis suggest the involvement of differentially expressed genes in multiple cellular signaling pathways into the reproductive mode transition, including phototransduction, cuticle composition, progesterone-mediated oocyte maturation and endocrine regulation. This study forms a basis for deciphering the molecular mechanisms underlying the shift from asexual to sexual reproduction in the cotton aphid. It also provides valuable resources for future studies on this host-alternating aphid species, and the insight into the understanding of reproductive mode plasticity in different aphid species.

  11. Alternative Astronomical FITS imaging

    CERN Document Server

    Varsaki, Eleni E; Fotopoulos, Vassilis; Skodras, Athanassios N

    2012-01-01

    Astronomical radio maps are presented mainly in FITS format. Astronomical Image Processing Software (AIPS) uses a set of tables attached to the output map to include all sorts of information concerning the production of the image. However this information together with information on the flux and noise of the map is lost as soon as the image of the radio source in fits or other format is extracted from AIPS. This information would have been valuable to another astronomer who just uses NED, for example, to download the map. In the current work, we show a method of data hiding inside the radio map, which can be preserved under transformations, even for example while the format of the map is changed from fits to other lossless available image formats.

  12. Fitting Galaxies on GPUs

    CERN Document Server

    Barsdell, Benjamin R; Fluke, Christopher J

    2011-01-01

    Structural parameters are normally extracted from observed galaxies by fitting analytic light profiles to the observations. Obtaining accurate fits to high-resolution images is a computationally expensive task, requiring many model evaluations and convolutions with the imaging point spread function. While these algorithms contain high degrees of parallelism, current implementations do not exploit this property. With evergrowing volumes of observational data, an inability to make use of advances in computing power can act as a constraint on scientific outcomes. This is the motivation behind our work, which aims to implement the model-fitting procedure on a graphics processing unit (GPU). We begin by analysing the algorithms involved in model evaluation with respect to their suitability for modern many-core computing architectures like GPUs, finding them to be well-placed to take advantage of the high memory bandwidth offered by this hardware. Following our analysis, we briefly describe a preliminary implementa...

  13. Fitting the Phenomenological MSSM

    CERN Document Server

    AbdusSalam, S S; Quevedo, F; Feroz, F; Hobson, M

    2010-01-01

    We perform a global Bayesian fit of the phenomenological minimal supersymmetric standard model (pMSSM) to current indirect collider and dark matter data. The pMSSM contains the most relevant 25 weak-scale MSSM parameters, which are simultaneously fit using `nested sampling' Monte Carlo techniques in more than 15 years of CPU time. We calculate the Bayesian evidence for the pMSSM and constrain its parameters and observables in the context of two widely different, but reasonable, priors to determine which inferences are robust. We make inferences about sparticle masses, the sign of the $\\mu$ parameter, the amount of fine tuning, dark matter properties and the prospects for direct dark matter detection without assuming a restrictive high-scale supersymmetry breaking model. We find the inferred lightest CP-even Higgs boson mass as an example of an approximately prior independent observable. This analysis constitutes the first statistically convergent pMSSM global fit to all current data.

  14. The universal Higgs fit

    DEFF Research Database (Denmark)

    Giardino, P. P.; Kannike, K.; Masina, I.;

    2014-01-01

    We perform a state-of-the-art global fit to all Higgs data. We synthesise them into a 'universal' form, which allows to easily test any desired model. We apply the proposed methodology to extract from data the Higgs branching ratios, production cross sections, couplings and to analyse composite H...... as an alternative to the Higgs, and disfavour fits with negative Yukawa couplings. We derive for the first time the SM Higgs boson mass from the measured rates, rather than from the peak positions, obtaining M-h = 124.4 +/- 1.6 GeV....

  15. Linking the Fits, Fitting the Links: Connecting Different Types of PO Fit to Attitudinal Outcomes

    Science.gov (United States)

    Leung, Aegean; Chaturvedi, Sankalp

    2011-01-01

    In this paper we explore the linkages among various types of person-organization (PO) fit and their effects on employee attitudinal outcomes. We propose and test a conceptual model which links various types of fits--objective fit, perceived fit and subjective fit--in a hierarchical order of cognitive information processing and relate them to…

  16. Talking Sport and Fitness

    Science.gov (United States)

    Dixon-Watmough, Rebecca; Keogh, Brenda; Naylor, Stuart

    2012-01-01

    For some time the Association for Science Education (ASE) has been aware that it would be useful to have some resources available to get children talking and thinking about issues related to health, sport and fitness. Some of the questions about pulse, breathing rate and so on are pretty obvious to everyone, and there is a risk of these being…

  17. Water Fit to Drink.

    Science.gov (United States)

    Donovan, Edward P.

    The major objective of this module is to help students understand how water from a source such as a lake is treated to make it fit to drink. The module, consisting of five major activities and a test, is patterned after Individualized Science Instructional System (ISIS) modules. The first activity (Planning) consists of a brief introduction and a…

  18. Fit for Life.

    Science.gov (United States)

    Vail, Kathleen

    1999-01-01

    Children who hate gym grow into adults who associate physical activity with ridicule and humiliation. Physical education is reinventing itself, stressing enjoyable activities that continue into adulthood: aerobic dance, weight training, fitness walking, mountain biking, hiking, inline skating, karate, rock-climbing, and canoeing. Cooperative,…

  19. Finding What Fits

    Science.gov (United States)

    Casey, Stephanie A.

    2016-01-01

    Statistical association between two variables is one of the fundamental statistical ideas in school curricula. Reasoning about statistical association has been deemed one of the most important cognitive activities that humans perform. Students are typically introduced to statistical association through the study of the line of best fit because it…

  20. Fitting a Gompertz curve

    NARCIS (Netherlands)

    Ph.H.B.F. Franses (Philip Hans)

    1994-01-01

    textabstractIn this paper, a simple Gompertz curve-fitting procedure is proposed. Its advantages include the facts that the stability of the saturation level over the sample period can be checked, and that no knowledge of its value is necessary for forecasting. An application to forecasting the stoc

  1. Kids Weigh to Fitness.

    Science.gov (United States)

    Maione, Mary Jane

    A description is given of a program that provides preventive measures to check obesity in children and young people. The 24-week program is divided into two parts--a nutrition component and an exercise component. At the start and end of the program, tests are given to assess the participants' height, weight, body composition, fitness level, and…

  2. Manual for physical fitness

    Science.gov (United States)

    Coleman, A. E.

    1981-01-01

    Training manual used for preflight conditioning of NASA astronauts is written for audience with diverse backgrounds and interests. It suggests programs for various levels of fitness, including sample starter programs, safe progression schedules, and stretching exercises. Related information on equipment needs, environmental coonsiderations, and precautions can help readers design safe and effective running programs.

  3. Extensive fitness and human cooperation.

    Science.gov (United States)

    van Hateren, J H

    2015-12-01

    Evolution depends on the fitness of organisms, the expected rate of reproducing. Directly getting offspring is the most basic form of fitness, but fitness can also be increased indirectly by helping genetically related individuals (such as kin) to increase their fitness. The combined effect is known as inclusive fitness. Here it is argued that a further elaboration of fitness has evolved, particularly in humans. It is called extensive fitness and it incorporates producing organisms that are merely similar in phenotype. The evolvability of this mechanism is illustrated by computations on a simple model combining heredity and behaviour. Phenotypes are driven into the direction of high fitness through a mechanism that involves an internal estimate of fitness, implicitly made within the organism itself. This mechanism has recently been conjectured to be responsible for producing agency and goals. In the model, inclusive and extensive fitness are both implemented by letting fitness increase nonlinearly with the size of subpopulations of similar heredity (for the indirect part of inclusive fitness) and of similar phenotype (for the phenotypic part of extensive fitness). Populations implementing extensive fitness outcompete populations implementing mere inclusive fitness. This occurs because groups with similar phenotype tend to be larger than groups with similar heredity, and fitness increases more when groups are larger. Extensive fitness has two components, a direct component where individuals compete in inducing others to become like them and an indirect component where individuals cooperate and help others who are already similar to them.

  4. Rõve kuubis, aga... / Tiit Tuumalu

    Index Scriptorium Estoniae

    Tuumalu, Tiit, 1971-

    2006-01-01

    Dokumentaalfilm "Aristokraadid", kus ühte roppu habemega anekdooti jutustavad meelelahutustööstusest tuntud tegijad : režissöör Paul Provenza : Ameerika Ühendriigid 2006. Filmi näitab Tallinna Kinomaja

  5. Usalda, aga kontrolli / Manuela Pihlap

    Index Scriptorium Estoniae

    Pihlap, Manuela

    2008-01-01

    Uuest isikuandmete kaitse seadusest. Ilmunud ka Harju Ekspress 22. veeb. 2008, lk. 6 ; Meie Maa 26. veeb. 2008, lk. 2 ; Pärnu Postimees 28. veeb. 2008, lk. 15 ; LõunaLeht 28. veeb. 2008, lk. 4 ; Valgamaalane 28. veeb. 2008, lk. 2

  6. Usalda, aga kontrolli / Manuela Pihlap

    Index Scriptorium Estoniae

    Pihlap, Manuela

    2008-01-01

    Uuest isikuandmete kaitse seadusest. Ilmunud ka Harju Ekspress 22. veeb. 2008, lk. 6 ; Meie Maa 26. veeb. 2008, lk. 2 ; Pärnu Postimees 28. veeb. 2008, lk. 15 ; LõunaLeht 28. veeb. 2008, lk. 4 ; Valgamaalane 28. veeb. 2008, lk. 2

  7. The role of sexual vs. asexual recruitment of Artemisia wudanica in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

    Science.gov (United States)

    Wang, Yongcui; Alberto, Busso Carlos; Jiang, Deming; Ala, Musa; Li, Xuehua; Zhou, Quanlai; Lin, Jixiang; Ren, Guohua; Jia, Lian

    2016-04-01

    Artemisia wudanica is an endemic, perennial, pioneering psammophyte species in the sand dune ecosystems of western Horqin Sand Land in northern China. However, no studies have addressed how sexual and asexual reproduction modes of A. wudanica perform at the transitional zones between active dune inter-dune lowlands and active dunes. In early spring, quadrats were randomly set up in the study area to monitor surviving seedling and/or ramet density and frequency coming from sexual/asexual reproduction of A. wudanica. Iron sticks were inserted near each quadrat to determine wind erosion intensity (WE). Additionally, soil samples were collected nearby each quadrat to test for soil moisture (SM), organic matter (OM) and pH. Surviving seedlings of A. wudanica showed an inverse response in comparison with ramets to SM, OM and WE. Soil moisture showed the most positive effect, and WE the negative effect, on surviving, sexual reproduction seedlings. Contrarily, WE had the most positive effect, and SM the negative effect, on asexual reproduction ramets. This suggests that increases in SM and decreases in WE should benefit recruitment of A. wudanica seedlings. On the contrary, ramets coming from asexual reproduction showed a different response to environmental factors in transition zone habitats. While SM was not a key constraint for the survival of seedlings, they showed a better, positive response to wind erosion environments. Overall, various study environmental parameters could be improved to foster A. wudanica invasion and settlement in the plant community through different reproductive modes, thereby promoting vegetation restoration and rehabilitation.

  8. Variation in the strength of male mate choice allows long-term coexistence of sperm-dependent asexuals and their sexual hosts.

    Science.gov (United States)

    Mee, Jonathan A; Otto, Sarah P

    2010-10-01

    In several asexual taxa, reproduction requires mating with related sexual species to stimulate egg development, even though genetic material is not incorporated from the sexuals (gynogenesis). In cases in which gynogens do not invest in male function, they can potentially have a twofold competitive advantage over sexuals because the asexuals avoid the cost of producing males. If unmitigated, however, the competitive success of the asexuals would ultimately lead to their own demise, following the extinction of the sexual species that stimulate egg development. We have studied a model of mate choice among sexual individuals and asexual gynogens, where males of the sexual species preferentially mate with sexual females over gynogenetic females, to determine if such mating preferences can stably maintain both gynogenetic and sexual individuals within a community. Our model shows that stable coexistence of gynogens and their sexual hosts can occur when there is variation among males in the degree of preference for mating with sexual females and when pickier males pay a higher cost of preference.

  9. Mechanisms of immune protection in the asexual blood stage infection by Plasmodium falciparum: analysis by in vitro and ex-vivo assays

    Directory of Open Access Journals (Sweden)

    Jurg Gysin

    1992-01-01

    Full Text Available Mechanisms of immune protection against the asexual blood stage infection by Plasmodium falciparum are reviewed. Recent studies of two independent lines of research developed at the Institute Pasteur, in humans and primate infections clearly indicate an obligatory interaction of antibodies and effector cells to express the anti-parasitic effect.

  10. A Puf RNA-binding protein encoding gene PlM90 regulates the sexual and asexual life stages of the litchi downy blight pathogen Peronophythora litchii.

    Science.gov (United States)

    Jiang, Liqun; Ye, Wenwu; Situ, Junjian; Chen, Yubin; Yang, Xinyu; Kong, Guanghui; Liu, Yaya; Tinashe, Runyanga J; Xi, Pinggen; Wang, Yuanchao; Jiang, Zide

    2017-01-01

    Sexual and asexual reproduction are two key processes in the pathogenic cycle of many filamentous pathogens. However in Peronophythora litchii, the causal pathogen for the litchi downy blight disease, critical regulator(s) of sexual or asexual differentiation has not been elucidated. In this study, we cloned a gene named PlM90 from P. litchii, which encodes a putative Puf RNA-binding protein. We found that PlM90 was highly expressed during asexual development, and much higher than that during sexual development, while relatively lower during cyst germination and plant infection. By polyethylene glycol (PEG)-mediated protoplast transformation, we generated three PlM90-silenced transformants and found a severely impaired ability in sexual spore production and a delay in stages of zoospore release and encystment. However, the pathogenicity of P. litchii was not affected by PlM90-silencing. Therefore we conclude that PlM90 specifically regulates the sexual and asexual differentiation of P. litchii.

  11. Sex pheromone of a coccoid insect with sexual and asexual lineages: fate of an ancestrally essential sexual signal in parthenogenetic females.

    Science.gov (United States)

    Tabata, Jun; Ichiki, Ryoko T; Moromizato, Chie; Mori, Kenji

    2017-03-01

    Sex pheromones play a central role in intersexual communication for reproduction in many organisms. Particularly in insects, reproductive isolation that leads to speciation is often achieved by shifts of pheromone chemistries. However, the divergence and evolution of pheromones remain largely unknown. This study reveals a unique evolutionary consequence for terpenoid pheromones in coccoid insects. Coccoids, such as mealybugs, show clear sexual dimorphism: males are dwarf and short-lived, whereas females are wingless and almost immobile. Female pheromones are therefore indispensable for males to navigate for sexual reproduction, but some females can reproduce asexually. Interestingly, a derived asexual lineage that reproduces by parthenogenesis coexists with its ancestral lineage that reproduces sexually in a population of the pineapple mealybug, Dysmicoccus brevipes Here, we isolated, characterized and synthesized a novel monoterpene, (-)-(anti-1,2-dimethyl-3-methylenecyclopentyl)acetaldehyde, as a pheromone of the sexual females of Dbrevipes This monoterpene aldehyde, with an irregular linkage of isoprene units, is notable, because all mealybug pheromones previously reported are carboxylic esters of terpenols. This compound was, however, never produced by the asexual females. As a consequence of acquiring parthenogenetic reproduction, the asexual females appear to have abandoned the production of the sex pheromone, which had been essential to attracting males in their ancestors.

  12. Extensive fitness and human cooperation

    NARCIS (Netherlands)

    van Hateren, J. H.

    2015-01-01

    Evolution depends on the fitness of organisms, the expected rate of reproducing. Directly getting offspring is the most basic form of fitness, but fitness can also be increased indirectly by helping genetically related individuals (such as kin) to increase their fitness. The combined effect is known

  13. MixFit

    DEFF Research Database (Denmark)

    Haller, Toomas; Leitsalu, Liis; Fischer, Krista

    2017-01-01

    Ancestry information at the individual level can be a valuable resource for personalized medicine, medical, demographical and history research, as well as for tracing back personal history. We report a new method for quantitatively determining personal genetic ancestry based on genome-wide data....... Numerical ancestry component scores are assigned to individuals based on comparisons with reference populations. These comparisons are conducted with an existing analytical pipeline making use of genotype phasing, similarity matrix computation and our addition-multidimensional best fitting by Mix......Fit. The method is demonstrated by studying Estonian and Finnish populations in geographical context. We show the main differences in the genetic composition of these otherwise close European populations and how they have influenced each other. The components of our analytical pipeline are freely available...

  14. Return to fitness.

    Science.gov (United States)

    Dinubile, Nicholas A

    2008-12-01

    The cornerstone of personal health is prevention. The concept of exercise as medicine is a lesson I have preached throughout my career, both with my patients in my private practice as well as through my years working with athletes at all levels including the Philadelphia 76ers basketball team and the Pennsylvania Ballet. It is also a message I relayed as a Special Advisor to the President's Council on Physical Fitness and Sports (PCPFS) during the first Bush administration, working closely with my old friend-and fitness advocate and visionary himself-Governor Arnold Schwarzenegger, who served as Chairman to the PCPFS. Arnold's impact on our nation's health was an extremely positive one that was felt in communities from coast-to-coast. Exercise, activity, and prevention were key components of his prescription for change and improved health for our country. He has also always personally inspired me to see my role as a physician and "healer" in a much broader context.

  15. Virtual Fitting Rooms

    OpenAIRE

    Becerra Rodríguez, Carlos Alfredo

    2016-01-01

    In the last decade a considerable number of efforts have been devoted into developing Virtual Fitting Rooms (VFR) due to the great popularity of Virtual Reality (VR) and Augmented Reality (AR) in the fashion design industry. The existence of new technologies such as Kinect, powerful web cameras and smartphones permit us to examine new ways to try on clothes without doing it physically in a store center. This research is primarily dedicated to review some important aspects about...

  16. BESⅢ track fitting algorithm

    Institute of Scientific and Technical Information of China (English)

    WANG Ji-Ke; MAO Ze-Pu; BIAN Jian-Ming; CAO Guo-Fu; CAO Xue-Xiang; CHEN Shen-Jian; DENG Zi-Yan; FU Cheng-Dong; GAO Yuan-Ning; HE Kang-Lin; HE Miao; HUA Chun-Fei; HUANG Bin; HUANG Xing-Tao; JI Xiao-Sin; LI Fei; LI Hai-Bo; LI Wei-Dong; LIANG Yu-Tie; LIU Chun-Xiu; LIU Huai-Min; LIU Suo; LIU Ying-Jie; MA Qiu-Mei; MA Xiang; MAO Ya-Jun; MO Xiao-Hu; PAN Ming-Hua; PANG Cai-Ying; PING Rong-Gang; QIN Ya-Hong; QIU Jin-Fa; SUN Sheng-Sen; SUN Yong-Zhao; WANG Liang-Liang; WEN Shuo-Pin; WU Ling-Hui; XIE Yu-Guang; XU Min; YAN Liang; YOU Zheng-Yun; YUAN Chang-Zheng; YUAN Ye; ZHANG Bing-Yun; ZHANG Chang-Chun; ZHANG Jian-Yong; ZHANG Xue-Yao; ZHANG Yao; ZHENG Yang-Heng; ZHU Ke-Jun; ZHU Yong-Sheng; ZHU Zhi-Li; ZOU Jia-Heng

    2009-01-01

    A track fitting algorithm based on the Kalman filter method has been developed for BESⅢ of BEPCⅡ.The effects of multiple scattering and energy loss when the charged particles go through the detector,non-uniformity of magnetic field (NUMF) and wire sag, etc., have been carefully handled.This algorithm works well and the performance satisfies the physical requirements tested by the simulation data.

  17. Made to fit

    DEFF Research Database (Denmark)

    Bjerck, Mari; Klepp, Ingun Grimstad; Skoland, Eli

    Denne rapporten formidler funn fra en litteraturstudie, brukerundersøkelse og markedsundersøkelse gjort i prosjektet Made to Fit. Rapporten svarer på prosjektets hovedmål og delmål som retter seg mot å formidle kunnskap om tilpasning og fremstilling av funksjonelle og gode produkter for handikapp......Denne rapporten formidler funn fra en litteraturstudie, brukerundersøkelse og markedsundersøkelse gjort i prosjektet Made to Fit. Rapporten svarer på prosjektets hovedmål og delmål som retter seg mot å formidle kunnskap om tilpasning og fremstilling av funksjonelle og gode produkter...... for handikappede. Herunder potensialet for å utvikle spesialtilpassede klær i konseptet «Made to Fit», utprøving av metoder og identifisering av kunnskapsstatus på feltet. Rapporten er således delt inn i tre hoveddeler. Første delen bygger videre på prosjektnotatet til Vestvik, Hebrok og Klepp (2013) fra...

  18. [Effect of weak and superweak magnetic fields on intensity and asexual reproduction of the planarian Dugesia tigrina].

    Science.gov (United States)

    Novikov, V V; Sheĭman, I M; Fesenko, E E

    2002-01-01

    It was shown that the exposure to combined weak and extraweak magnetic fields (permanent component 42 microT; variable component of an amplitude of 100 nT, frequency 1-60 Hz) increases the intensity of asexual propagation of planarians Dugesia tigrina. The effect of combined magnetic fields is most pronounced at frequencies of 1, 3.7, and 32 Hz. The presence of concomitant technogeneous fields (50 Hz, 30 nT) does not markedly influence the effects of weak magnetic fields with a small variable component. Upon realization of effects of weak magnetic fields, their both components are of great importance; the absence of one (permanent) component changes the sing of the effect to the opposite. The transfer of the effect to planarians through water pretreated with magnetic fields probably indicates that aqueous medium is involved in the realization of biological effects of weak magnetic fields.

  19. Life cycle of the multiarmed sea star Coscinasterias acutispina (Stimpson, 1862) in laboratory culture: sexual and asexual reproductive pathways.

    Science.gov (United States)

    Shibata, Daisuke; Hirano, Yoshiaki; Komatsu, Miéko

    2011-05-01

    The multiarmed sea star Coscinasterias acutispina generally has 7-10 arms and 2-5 madreporites. It is known to be able to reproduce by asexual fission, and we have previously observed that this species also has the ability to reproduce sexually; however, there has been no report until now of spawning in this species. We succeeded in establishing a long-term culture of juveniles produced by artificial fertilization. Twelve months after the completion of metamorphosis, three individuals had six arms of the same length and a madreporite. At this time, fission occurred in two of these individuals, while the remaining individual underwent fission four months later. Each sea star divided into two halves, provided with three arms each. Thereafter, four or five new arms and two or four madreporites were formed anew in each of the six daughter sea-stars, so that by 30 days after the first fission the number of arms and madreporites in each was similar to that in adults. A second fission occurred in four of these six individuals, four or five months after the first fission, and in three of them the plane of division was the same as that of the first fission. The original three individuals eventually proliferated to 12 by undergoing fission. All individuals had fully developed gonads by 1-3 months after the second fission. Some of them eventually spawned under laboratory culture, and the resulting larvae metamorphosed into juveniles. Our observations demonstrate that individuals of C. acutispina possess the potential for both sexual and asexual reproduction.

  20. Investment choices in post-embryonic development: quantifying interactions among growth, regeneration, and asexual reproduction in the annelid Pristina leidyi.

    Science.gov (United States)

    Zattara, Eduardo E; Bely, Alexandra E

    2013-12-01

    Animals capable of multiple forms of post-embryonic development, such as growth, regeneration, and asexual reproduction, must make choices about which processes to invest in. What strategies guide post-embryonic resource allocation investments? We investigated this question in the annelid Pristina leidyi, which can grow continuously, regenerates well, and reproduces asexually by fission. We found that in this species growth is concentrated in three zones: a subterminal posterior zone (forming new segments), a mid-body zone (forming fission zones), and a previously undescribed subterminal anterior zone at the base of the prostomium (which we suggest continually builds the prostomium through a "conveyor-belt" like process). Body-wide counts of proliferating cells are greater under high food than low food conditions but proliferation patterns themselves are independent of feeding level. Proliferation patterns are strongly affected by amputation, however, with proliferation rapidly shutting-down throughout the body, except at the wound site, following injury. Relative investment to fission and regeneration is highly context-dependent, being sensitive to the position of the cut and the stage of fission. Outcomes range from fission acceleration and regeneration stalling (high fission:regeneration investment) to resorption of fission zones and progression of regeneration (low fission:regeneration investment). Our findings reveal strong interactions between growth, regeneration, and fission and demonstrate a particularly important effect of injury on resource allocation patterns. Patterns of resource investment in P. leidyi show similarities to those described in two other groups that evolved fission independently (naidine annelids and catenulid flatworms), suggesting that similar developmental and physiological contexts may drive convergent evolution of resource allocation strategies. © 2013 Wiley Periodicals, Inc.

  1. Asexual genome evolution in the apomictic Ranunculus auricomus complex: examining the effects of hybridization and mutation accumulation.

    Science.gov (United States)

    Pellino, Marco; Hojsgaard, Diego; Schmutzer, Thomas; Scholz, Uwe; Hörandl, Elvira; Vogel, Heiko; Sharbel, Timothy F

    2013-12-01

    Asexual lineages are thought to be prone to extinction because of deleterious mutation accumulation (Muller's ratchet). Here, we analyse genomic effects of hybridity, polyploidy and allelic divergence in apomictic plants, and identify loci under divergent selection among sexual/apomictic lineages. RNAseq was used to sequence the flower-specific transcriptomes of five genotypes of the Ranunculus auricomus complex, representing three sexual and two apomictic reproductive biotypes. The five sequence libraries were pooled and de novo assembly performed, and the resultant assembly was used as a backbone for a subsequent alignment of each separate library. High-quality single-nucleotide (SNP) and insertion-deletion (indel) polymorphisms were mined from each library. Annotated genes for which open reading frames (ORF) could be determined were analysed for signatures of divergent versus stabilizing selection. A comparison between all genotypes supports the hypothesis of Pleistocene hybrid origin of both apomictic genotypes from R. carpaticola and R. cassubicifolius, with subsequent allelic divergence of apomictic lineages (Meselson effect). Pairwise comparisons of nonsynonymous (dN) to synonymous (dS) substitution rate ratios between apomictic and sexual genotypes for 1231 genes demonstrated similar distributions for all comparisons, although 324 genes demonstrated outlier (i.e. elevated) dN/dS ratios. Gene ontology analyses of these outliers revealed significant enrichment of genes associated with reproduction including meiosis and gametogenesis, following predictions of divergent selection between sexual and apomictic reproduction, although no significant signal of genome-wide mutation accumulation could be identified. The results suggest that gene function should be considered in order to understand effects of mutation accumulation in asexual lineages.

  2. F-statistics under alternation of sexual and asexual reproduction: a model and data from schistosomes (platyhelminth parasites).

    Science.gov (United States)

    Prugnolle, Franck; Roze, Denis; Théron, André; DE Meeûs, Thierry

    2005-04-01

    Accurate inferences on population genetics data require a sound underlying theoretical null model. Nearly nothing is known about the gene dynamics of organisms with complex life cycles precluding any biological interpretation of population genetics parameters. In this article, we used an infinite island model to derive the expectations of those parameters for the life cycle of a dioecious organism obligatorily alternating sexual and asexual reproductions as it is the case for schistosomes (plathyhelminth parasites). This model allowed us to investigate the effects of the degree of mixing among individuals coming from different subpopulations at each new generation (represented in the model by the migration rates before and after clonal reproductions) and the variance in the reproductive success of individuals during the clonal phase. We also consider the effects of different migration rates and degrees of clonal reproductive skew between male and female individuals. Results show that the variance in the reproductive success of clones is very important in shaping the distribution of the genetic variability both within and among subpopulations. Thus, higher variance in the reproductive success of clones generates heterozygous excesses within subpopulations and also increases genetic differentiation between them. Migration occurring before and after asexual reproduction has different effects on the patterns of F(IS) and F(ST). When males and females display different degrees of reproductive skew or migration rates, we observe differences in their respective population genetic structure. While results of the model apply to any organism alternating sexual and clonal reproductions (e.g. all parasitic trematodes, many plants, and all aphididae), we finally confront some of these theoretical expectations to empirical data from Schistosoma mansoni infecting Rattus rattus in Guadeloupe.

  3. Invasion fitness, inclusive fitness, and reproductive numbers in heterogeneous populations.

    Science.gov (United States)

    Lehmann, Laurent; Mullon, Charles; Akçay, Erol; Van Cleve, Jeremy

    2016-08-01

    How should fitness be measured to determine which phenotype or "strategy" is uninvadable when evolution occurs in a group-structured population subject to local demographic and environmental heterogeneity? Several fitness measures, such as basic reproductive number, lifetime dispersal success of a local lineage, or inclusive fitness have been proposed to address this question, but the relationships between them and their generality remains unclear. Here, we ascertain uninvadability (all mutant strategies always go extinct) in terms of the asymptotic per capita number of mutant copies produced by a mutant lineage arising as a single copy in a resident population ("invasion fitness"). We show that from invasion fitness uninvadability is equivalently characterized by at least three conceptually distinct fitness measures: (i) lineage fitness, giving the average individual fitness of a randomly sampled mutant lineage member; (ii) inclusive fitness, giving a reproductive value weighted average of the direct fitness costs and relatedness weighted indirect fitness benefits accruing to a randomly sampled mutant lineage member; and (iii) basic reproductive number (and variations thereof) giving lifetime success of a lineage in a single group, and which is an invasion fitness proxy. Our analysis connects approaches that have been deemed different, generalizes the exact version of inclusive fitness to class-structured populations, and provides a biological interpretation of natural selection on a mutant allele under arbitrary strength of selection.

  4. 不同无性繁殖造林小黑杨生物量模型研究%Study on biomass models of Populus×xiaohei with different asexual propagation afforestation

    Institute of Scientific and Technical Information of China (English)

    姜鹏; 秦召文; 王永明; 谷建才; 王桂真

    2014-01-01

    In order to investigate the biomass state of Populus×xiaohei which was afforested by different ways of asexual reproduction in Bashang region of Zhangjiakou city, by taking Populus×xiaohei plantation afforested by asexual reproduction in Zhangbei county and Guyuan county as study objects, the biomass data of Populus×xiaohei were measured by stem analysis and harvesting methods, which were afforested by cuttage, mark-and-sweep and pile anchoring, and the biomass models of Populus×xiaohei afforested by the three ways were fitted by adopting SPSS18.0. The results indicate that (1) The coefficients of determination (R2) of nonlinear regression models were all greater than 0.96, D1.3 and D1.32H can account for biomass of each organ very well;(2) The Logistic equation model for Populus×xiaohei afforested by cottage, the power function model for Populus×xiaohei afforested by mark-and-sweep, and the Logistic equation model for Populus×xiaohei afforested by pile anchoring has been built.%旨在研究张家口坝上地区不同无性繁殖造林小黑杨生物量状况,以张家口坝上张北、沽源的无性繁殖造林小黑杨为研究对象,采用树干解析和收割的方法获取插条、断根和埋桩造林的小黑杨的生物量实测数据,利用SPSS18.0拟合3种无性繁殖造林小黑杨的生物量模型,其结果表明:(1)非线性回归模型的判定系数R2都大于0.96,D1.3和D1.32H能够很好解释各器官生物量。(2)分别建立了插条造林小黑杨生物量的Logistic方程模型、断根造林小黑杨生物量的幂函数模型和埋桩造林小黑杨生物量的Logistic方程模型。

  5. Fit for work

    DEFF Research Database (Denmark)

    Brorholt, Grete

    "Fit for work - Attraktiv sundhed og sikkerhed på en hospitalsafdeling i Region Hovedstaden" undersøger hvorledes sundhedsvæsenets forandringer påvirker medarbejdere, ledere og organisation. Udgangspunktet for afhandlingen er en interesse for psykisk arbejdsmiljø, og hvordan reformerne i kølvandet...... også belastende arbejdsmiljø. Afhandlingen er baseret på 8 måneders deltagerobservation og interviews på en anæstesiologisk afdeling kombineret med omfattende dokumentlæsning....

  6. Adaptive Vertex Fitting

    CERN Document Server

    Frühwirth, R; Vanlaer, Pascal

    2007-01-01

    Vertex fitting frequently has to deal with both mis-associated tracks and mis-measured track errors. A robust, adaptive method is presented that is able to cope with contaminated data. The method is formulated as an iterative re-weighted Kalman filter. Annealing is introduced to avoid local minima in the optimization. For the initialization of the adaptive filter a robust algorithm is presented that turns out to perform well in a wide range of applications. The tuning of the annealing schedule and of the cut-off parameter is described, using simulated data from the CMS experiment. Finally, the adaptive property of the method is illustrated in two examples.

  7. Absence of Helicobacter pylori high tetracycline resistant 16S rDNA AGA926-928TTC genotype in gastric biopsy specimens from dyspeptic patients of a city in the interior of São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Suzuki Rodrigo

    2012-05-01

    Full Text Available Abstract Background Treatment effectiveness of Helicobacter pylori varies regionally and is decreasing worldwide, principally as a result of antibiotic resistant bacterium. Tetracycline is generally included in second line H. pylori eradication regimens. In Brazil, a high level of tetracycline resistance (TetR is mainly associated with AGA926-928TTC 16 S rDNA nucleotide substitutions. As H. pylori culture is fastidious, we investigated the primary occurrence of H. pylori 16 S rDNA high level TetR genotype using a molecular approach directly on gastric biopsies of dyspeptic patients attending consecutively at Hospital das Clinicas of Marilia, São Paulo, Brazil. Methods Gastric biopsy specimens of 68 peptic ulcer disease (PUD and 327 chronic gastritis (CG patients with a positive histological diagnosis of H. pylori were investigated for TetR 16 S rDNA genotype through a molecular assay based on amplification of a 16 S rDNA 545 bp fragment by polymerase chain reaction and HinfI restriction fragment length polymorphism (PCR/RFLP. Through this assay, AGA926-928TTC 16 S rDNA TetR genotype resulted in a three DNA fragment restriction pattern (281, 227 and 37 bp and its absence originated two DNA fragments (264 and 281 bp due to a 16 S rDNA conserved Hinf I restriction site. Results The 545 bp 16 S rDNA PCR fragment was amplified from 90% of gastric biopsies from histological H. pylori positive patients. HinfI RFLP revealed absence of the AGA926–928TTC H. pylori genotype and PCR products of two patients showed absence of the conserved 16 S rDNA HinfI restriction site. BLASTN sequence analysis of four amplicons (two conserved and two with an unpredicted HinfI restriction pattern revealed a 99% homology to H. pylori 16 S rDNA from African, North and South American bacterial isolates. A nucleotide substitution abolished the conserved HinfI restriction site in the two PCR fragments with unpredicted HinfI RFLP, resulting in an

  8. Asexual reproduction induces a rapid and permanent loss of sexual reproduction capacity in the rice fungal pathogen Magnaporthe oryzae: results of in vitro experimental evolution assays

    Directory of Open Access Journals (Sweden)

    Saleh Dounia

    2012-03-01

    Full Text Available Abstract Background Sexual reproduction is common in eukaryotic microorganisms, with few species reproducing exclusively asexually. However, in some organisms, such as fungi, asexual reproduction alternates with episodic sexual reproduction events. Fungi are thus appropriate organisms for studies of the reasons for the selection of sexuality or clonality and of the mechanisms underlying this selection. Magnaporthe oryzae, an Ascomycete causing blast disease on rice, reproduces mostly asexually in natura. Sexual reproduction is possible in vitro and requires (i two strains of opposite mating types including (ii at least one female-fertile strain (i.e. a strain able to produce perithecia, the female organs in which meiosis occurs. Female-fertile strains are found only in limited areas of Asia, in which evidence for contemporary recombination has recently been obtained. We induced the forced evolution of four Chinese female-fertile strains in vitro by the weekly transfer of asexual spores (conidia between Petri dishes. We aimed to determine whether female fertility was rapidly lost in the absence of sexual reproduction and whether this loss was controlled genetically or epigenetically. Results All the strains became female-sterile after 10 to 19 rounds of selection under asexual conditions. As no single-spore isolation was carried out, the observed decrease in the production of perithecia reflected the emergence and the invasion of female-sterile mutants. The female-sterile phenotype segregated in the offspring of crosses between female-sterile evolved strains and female-fertile wild-type strains. This segregation was maintained in the second generation in backcrosses. Female-sterile evolved strains were subjected to several stresses, but none induced the restoration of female fertility. This loss of fertility was therefore probably due to genetic rather than epigenetic mechanisms. In competition experiments, female-sterile mutants produced similar

  9. Quantifying the role of population subdivision in evolution on rugged fitness landscapes.

    Science.gov (United States)

    Bitbol, Anne-Florence; Schwab, David J

    2014-08-01

    Natural selection drives populations towards higher fitness, but crossing fitness valleys or plateaus may facilitate progress up a rugged fitness landscape involving epistasis. We investigate quantitatively the effect of subdividing an asexual population on the time it takes to cross a fitness valley or plateau. We focus on a generic and minimal model that includes only population subdivision into equivalent demes connected by global migration, and does not require significant size changes of the demes, environmental heterogeneity or specific geographic structure. We determine the optimal speedup of valley or plateau crossing that can be gained by subdivision, if the process is driven by the deme that crosses fastest. We show that isolated demes have to be in the sequential fixation regime for subdivision to significantly accelerate crossing. Using Markov chain theory, we obtain analytical expressions for the conditions under which optimal speedup is achieved: valley or plateau crossing by the subdivided population is then as fast as that of its fastest deme. We verify our analytical predictions through stochastic simulations. We demonstrate that subdivision can substantially accelerate the crossing of fitness valleys and plateaus in a wide range of parameters extending beyond the optimal window. We study the effect of varying the degree of subdivision of a population, and investigate the trade-off between the magnitude of the optimal speedup and the width of the parameter range over which it occurs. Our results, obtained for fitness valleys and plateaus, also hold for weakly beneficial intermediate mutations. Finally, we extend our work to the case of a population connected by migration to one or several smaller islands. Our results demonstrate that subdivision with migration alone can significantly accelerate the crossing of fitness valleys and plateaus, and shed light onto the quantitative conditions necessary for this to occur.

  10. Methodology review: evaluating person fit

    NARCIS (Netherlands)

    Meijer, R.R.; Sijtsma, Klaas

    2001-01-01

    Person-fit methods based on classical test theory-and item response theory (IRT), and methods investigating particular types of response behavior on tests, are examined. Similarities and differences among person-fit methods and their advantages and disadvantages are discussed. Sound person-fit

  11. SE-FIT

    Science.gov (United States)

    Chen, Yongkang; Weislogel, Mark; Schaeffer, Ben; Semerjian, Ben; Yang, Lihong; Zimmerli, Gregory

    2012-01-01

    The mathematical theory of capillary surfaces has developed steadily over the centuries, but it was not until the last few decades that new technologies have put a more urgent demand on a substantially more qualitative and quantitative understanding of phenomena relating to capillarity in general. So far, the new theory development successfully predicts the behavior of capillary surfaces for special cases. However, an efficient quantitative mathematical prediction of capillary phenomena related to the shape and stability of geometrically complex equilibrium capillary surfaces remains a significant challenge. As one of many numerical tools, the open-source Surface Evolver (SE) algorithm has played an important role over the last two decades. The current effort was undertaken to provide a front-end to enhance the accessibility of SE for the purposes of design and analysis. Like SE, the new code is open-source and will remain under development for the foreseeable future. The ultimate goal of the current Surface Evolver Fluid Interface Tool (SEFIT) development is to build a fully integrated front-end with a set of graphical user interface (GUI) elements. Such a front-end enables the access to functionalities that are developed along with the GUIs to deal with pre-processing, convergence computation operation, and post-processing. In other words, SE-FIT is not just a GUI front-end, but an integrated environment that can perform sophisticated computational tasks, e.g. importing industry standard file formats and employing parameter sweep functions, which are both lacking in SE, and require minimal interaction by the user. These functions are created using a mixture of Visual Basic and the SE script language. These form the foundation for a high-performance front-end that substantially simplifies use without sacrificing the proven capabilities of SE. The real power of SE-FIT lies in its automated pre-processing, pre-defined geometries, convergence computation operation

  12. Research on the Technique of Fault Diagnosis Based on Adaptive Genetic Algorithm and BP Neural Network%基于AGA-BP算法的智能故障诊断技术研究

    Institute of Scientific and Technical Information of China (English)

    焦爱红; 袁力哲; 陈燕生

    2011-01-01

    Fault diagnosis algorithm based on adaptive genetic algorithm and BP neural network (AGA-BP) was presented to avoid the defect of tradition BP neural networks. The adaptive genetic algorithm was used to optimize initial weights and thresholds of the BP neural network in earlier stage of iterative calculation, and the error hack propagation algorithm with self study speed was used to improve the network problems of slow convergence speed in the later stage. The AGA-BP algorithm was used to diagnose grinding bum fault. The result was compared with that of the general network algorithm. It testifies the method is correct and valid.%针对传统BP神经网络的不足,提出基于自适应遗传算法的BP神经网络故障诊断算法.在迭代计算前期,采用自适应遗传算法对神经网络的权值和阈值进行全局优化;在迭代计算后期,利用改进的BP算法在近似最优解附近进行局部寻优.将该算法用于磨削烧伤的故障诊断之中,并将结果与基于改进BP网络的诊断结果进行比较,证明该方法的正确性和有效性.

  13. A Gene Expressed during Sexual and Asexual Sporulation in Phytophthora infestans is a Member of the Puf Family of Translational Regulators

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Judelson, Howard S.

    2003-01-01

    A gene from Phytophthora infestans that was previously identified as being induced during the development of sexual spores was also found to be active during asexual sporulation. The gene, M90, was expressed as a 3.1-kb primary transcript containing two introns and was predicted to encode a member...... of the Puf family of translational regulators. The protein showed up to 51% amino acid identity to other Puf proteins within its 353-amino-acid RNA-binding domain. Little similarity extended beyond this region, as noted for other members of the family. Expression of M90 was measured by using RNA blots....... Potential roles for a translational regulator during both sexual development and asexual sporulation are discussed....

  14. Definitions of fitness in age-structured populations: Comparison in the haploid case.

    Science.gov (United States)

    Lessard, Sabin; Soares, Cintia

    2016-02-21

    Fisher's (1930) Fundamental Theorem of Natural Selection (FTNS), and in particular the development of an explicit age-structured version of the theorem, is of everlasting interest. In a recent paper, Grafen (2015a) argues that Fisher regarded his theorem as justifying individual rather than population fitness maximization. The argument relies on a new definition of fitness in age-structured populations in terms of individual birth and death rates and age-specific reproductive values in agreement with a principle of neutrality. The latter are frequency-dependent and defined without reference to genetic variation. In the same paper, it is shown that the rate of increase in the mean of the breeding values of fitness weighted by the reproductive values, but keeping the breeding values constant as in Price (1972) is equal to the additive genetic variance in fitness. Therefore, this partial change is obtained by keeping constant not only the genotypic birth and death rates but also the mean age-specific birth and death rates from which the age-specific reproductive values are defined. In this paper we reaffirm that the Malthusian parameter which measures the relative rate of increase or decrease in reproductive value of each genotype in a continuous-time age-structured population is the definition of fitness used in Fisher's (1930) FTNS. This is shown by considering an age-structured asexual haploid population with constant age-specific birth and death (or survival) parameters for each type. Although the original statement of the FTNS is for a diploid population, this simplified haploid model allows us to address the definition of fitness meant in this theorem without the complexities and effects of a changing genic environment. In this simplified framework, the rate of change in mean fitness in continuous time is expected to be exactly equal to the genetic variance in fitness (or to the genetic variance in fitness divided by the mean fitness in discrete time), which can

  15. Carriage of sub-microscopic sexual and asexual Plasmodium falciparum stages in the dry season at Navrongo, Ghana.

    Science.gov (United States)

    Atelu, Geoffrey R; Duah, Nancy O; Wilson, Michael D

    2016-12-01

    We investigated the prevalence of sub-microscopic Plasmodium falciparum infections and gametocyte carriage in asymptomatic individuals in Navrongo in northern Ghana, an area of seasonal malaria transmission. A cross sectional study of 209 randomly selected participants of all age-groups was conducted in February and March, 2015. Capillary blood samples collected from these individuals were used for the detection of both asexual and gametocyte stage parasites by microscopy, reverse transcriptase polymerase chain reaction (RT-PCR) and conventional nested PCR methods. The prevalence data as determined by microscopy and molecular methods were compared using chi-square tests. Parasitaemia from these asymptomatic infections ranged from 40 to 3,520 parasites/µl of blood (geometric mean parasitaemia = 732 parasites/µl). The prevalence of asymptomatic P. falciparum carriage was 4.8% (10/209) and 13.9% (29/209) using microscopy and RT-PCR respectively. The overall prevalence of sub-microscopic infections in the total number of samples analysed was 9.1% (19/209) and 66% (19/29) of the asymptomatic infections. P. falciparum gametocytemia detected by microscopy was 1% (2/209) and 3.8% (8/209) by PCR. This is the first report of sub-microscopic asexual and gametocytes infections in the dry season in a seasonal malaria transmission area in Ghana. It has established that persistent latent malaria infections occur and that these could supply the source of parasites for the next transmission season. The findings highlight the presence of sub-microscopic infections and therefore the need for active case detection surveillance to eliminate "asymptomatic reservoir" parasites and consequently break the transmission of the disease in Ghana. Bill and Melinda Gates Foundation grant awarded to Noguchi Memorial Institute for Medical Research Postdoctoral and Postgraduate Training in Infectious Diseases Research (Global Health Grant # OPP52155); National Institutes of Health grant (NIH

  16. Fusion: a tale of recombination in an asexual fungus: The role of nuclear dynamics and hyphal fusion in horizontal chromosome transfer in Fusarium oxysporum

    OpenAIRE

    Shahi, S.

    2016-01-01

    Recent studies have shown that not only meiotic recombination is responsible for the fast evolution of fungal pathogens. In the asexual fungus F. oxysporum (Fo) the "fast" evolving part of the genome is organized into small chromosomes and one such chromosome houses all effector genes and is referred to as the "pathogenicity" chromosome. This pathogenicity chromosome can be horizontally transferred to a non-pathogenic strain, conferring pathogenicity. Here we use Fo as a model organism to add...

  17. Isolation and analysis of differentially expressed genes during asexual sporulation in liquid static culture of Ganoderma lucidum by suppression subtractive hybridization.

    Science.gov (United States)

    Xu, Jun-Wei; Zhao, Wei; Xu, Yi-Ning; Zhong, Jian-Jiang

    2012-04-01

    Ganoderma lucidum differentiates in liquid static culture by forming aerial mycelia and asexual spores, and this differentiation process is accompanied by higher production of anti-tumor compounds ganoderic acids. To gain an insight into the molecular events during asexual sporulation of G. lucidum, comparative transcriptome analysis using suppression subtractive hybridization (SSH) technique was performed to identify preferentially expressed genes in liquid static culture vs. in traditional shaking culture. After macroarray analysis of 1920 cDNAs from SSH library, 147 unigenes which exhibited high expression in static culture were identified. Among these sequences, putative translations of 88 unigenes possessed much similarity to known proteins involved in cell organization, signal transduction, cell metabolism, protein biosynthesis and transcription regulation; 13 had significant similarity to hypothetical proteins; the remaining 46 showed little or no similarity to GenBank sequences. RT-qPCR analysis confirmed increases in transcripts of selected genes under liquid static culture condition. The results of this study present the useful application of EST analysis on G. lucidum and provide preliminary indication of gene expression putatively involved in asexual sporulation process.

  18. The pattern of genetic variability in apomictic clones of Taraxacum officinale indicates the alternation of asexual and sexual histories of apomicts.

    Directory of Open Access Journals (Sweden)

    Luboš Majeský

    Full Text Available Dandelions (genus Taraxacum comprise a group of sexual diploids and apomictic polyploids with a complicated reticular evolution. Apomixis (clonal reproduction through seeds in this genus is considered to be obligate, and therefore represent a good model for studying the role of asexual reproduction in microevolutionary processes of apomictic genera. In our study, a total of 187 apomictic individuals composing a set of nine microspecies (sampled across wide geographic area in Europe were genotyped for six microsatellite loci and for 162 amplified fragment length polymorphism (AFLP markers. Our results indicated that significant genetic similarity existed within accessions with low numbers of genotypes. Genotypic variability was high among accessions but low within accessions. Clustering methods discriminated individuals into nine groups corresponding to their phenotypes. Furthermore, two groups of apomictic genotypes were observed, which suggests that they had different asexual histories. A matrix compatibility test suggests that most of the variability within accession groups was mutational in origin. However, the presence of recombination was also detected. The accumulation of mutations in asexual clones leads to the establishment of a network of clone mates. However, this study suggests that the clones primarily originated from the hybridisation between sexual and apomicts.

  19. The pattern of genetic variability in apomictic clones of Taraxacum officinale indicates the alternation of asexual and sexual histories of apomicts.

    Science.gov (United States)

    Majeský, Luboš; Vašut, Radim J; Kitner, Miloslav; Trávníček, Bohumil

    2012-01-01

    Dandelions (genus Taraxacum) comprise a group of sexual diploids and apomictic polyploids with a complicated reticular evolution. Apomixis (clonal reproduction through seeds) in this genus is considered to be obligate, and therefore represent a good model for studying the role of asexual reproduction in microevolutionary processes of apomictic genera. In our study, a total of 187 apomictic individuals composing a set of nine microspecies (sampled across wide geographic area in Europe) were genotyped for six microsatellite loci and for 162 amplified fragment length polymorphism (AFLP) markers. Our results indicated that significant genetic similarity existed within accessions with low numbers of genotypes. Genotypic variability was high among accessions but low within accessions. Clustering methods discriminated individuals into nine groups corresponding to their phenotypes. Furthermore, two groups of apomictic genotypes were observed, which suggests that they had different asexual histories. A matrix compatibility test suggests that most of the variability within accession groups was mutational in origin. However, the presence of recombination was also detected. The accumulation of mutations in asexual clones leads to the establishment of a network of clone mates. However, this study suggests that the clones primarily originated from the hybridisation between sexual and apomicts.

  20. Robust inducible Cre recombinase activity in the human malaria parasite Plasmodium falciparum enables efficient gene deletion within a single asexual erythrocytic growth cycle.

    Science.gov (United States)

    Collins, Christine R; Das, Sujaan; Wong, Eleanor H; Andenmatten, Nicole; Stallmach, Robert; Hackett, Fiona; Herman, Jean-Paul; Müller, Sylke; Meissner, Markus; Blackman, Michael J

    2013-05-01

    Asexual blood stages of the malaria parasite, which cause all the pathology associated with malaria, can readily be genetically modified by homologous recombination, enabling the functional study of parasite genes that are not essential in this part of the life cycle. However, no widely applicable method for conditional mutagenesis of essential asexual blood-stage malarial genes is available, hindering their functional analysis. We report the application of the DiCre conditional recombinase system to Plasmodium falciparum, the causative agent of the most dangerous form of malaria. We show that DiCre can be used to obtain rapid, highly regulated site-specific recombination in P. falciparum, capable of excising loxP-flanked sequences from a genomic locus with close to 100% efficiency within the time-span of a single erythrocytic growth cycle. DiCre-mediated deletion of the SERA5 3' UTR failed to reduce expression of the gene due to the existence of alternative cryptic polyadenylation sites within the modified locus. However, we successfully used the system to recycle the most widely used drug resistance marker for P. falciparum, human dihydrofolate reductase, in the process producing constitutively DiCre-expressing P. falciparum clones that have broad utility for the functional analysis of essential asexual blood-stage parasite genes.

  1. Evolutionary dynamics of the most populated genotype on rugged fitness landscapes

    Science.gov (United States)

    Jain, Kavita

    2007-09-01

    We consider an asexual population evolving on rugged fitness landscapes which are defined on the multidimensional genotypic space and have many local optima. We track the most populated genotype as it changes when the population jumps from a fitness peak to a better one during the process of adaptation. This is done using the dynamics of the shell model which is a simplified version of the quasispecies model for infinite populations and standard Wright-Fisher dynamics for large finite populations. We show that the population fraction of a genotype obtained within the quasispecies model and the shell model match for fit genotypes and at short times, but the dynamics of the two models are identical for questions related to the most populated genotype. We calculate exactly several properties of the jumps in infinite populations, some of which were obtained numerically in previous works. We also present our preliminary simulation results for finite populations. In particular, we measure the jump distribution in time and find that it decays as t-2 as in the quasispecies problem.

  2. Termite queens close the sperm gates of eggs to switch from sexual to asexual reproduction.

    Science.gov (United States)

    Yashiro, Toshihisa; Matsuura, Kenji

    2014-12-02

    Males and females are in conflict over genetic transmission in the evolution of parthenogenesis, because it enhances female reproductive output but deprives the males' genetic contribution. For males, any trait that coerces females into sexual reproduction should increase their fitness. However, in the termite Reticulitermes speratus, queens produce their replacements (neotenic queens) parthenogenetically while using normal sexual reproduction to produce other colony members. Here, we show that termite queens produce parthenogenetic offspring in the presence of kings by closing the micropyles (sperm gates; i.e., openings for sperm entry) of their eggs. Our field survey showed that termite eggs show large variation in numbers of micropyles, with some having none. Microsatellite analysis showed that embryos of micropyleless eggs develop parthenogenetically, whereas those of eggs with micropyles are fertilized and develop sexually. Surveys of eggs among queens of different age groups showed that queens begin to lay micropyleless eggs when they are older and thus, need to produce their replacements parthenogenetically. In addition, we found clear seasonality in new neotenic queen differentiation and micropyleless egg production. This micropyle-dependent parthenogenesis is the first identification, to our knowledge, of the mechanism through which females control egg fertilization over time in diploid animals, implying a novel route of the evolution of parthenogenesis in favor of female interests without interference from males.

  3. LAMMER Kinase LkhA plays multiple roles in the vegetative growth and asexual and sexual development of Aspergillus nidulans.

    Directory of Open Access Journals (Sweden)

    Eun-Hye Kang

    Full Text Available LAMMER kinase plays pivotal roles in various physiological processes in eukaryotes; however, its function in filamentous fungi is not known. We performed molecular studies on the function of the Aspergillus nidulans LAMMER kinase, LkhA, and report its involvement in multiple developmental processes. The gene for LkhA was highly expressed during reproductive organ development, such as that of conidiophores and cleistothecia. During vegetative growth, the patterns of germ tube emergence and hyphal polarity were changed and septation was increased by lkhA deletion. Northern analyses showed that lkhA regulated the transcription of brlA, csnD, and ppoA, which supported the detrimental effect of lkhA-deletion on asexual and sexual differentiation. LkhA also affected expression of cyclin-dependent kinase NimX(cdc2, a multiple cell cycle regulator, and StuA, an APSES family of fungal transcription factors that play pivotal roles in multiple differentiation processes. Here, for the first time, we present molecular evidence showing that LAMMER kinase is involved in A. nidulans development by modulating the expression of key regulators of developmental processes.

  4. Genomic and metabolic characterisation of alkaloid biosynthesis by asexual Epichloë fungal endophytes of tall fescue pasture grasses.

    Science.gov (United States)

    Ekanayake, Piyumi N; Kaur, Jatinder; Tian, Pei; Rochfort, Simone J; Guthridge, Kathryn M; Sawbridge, Timothy I; Spangenberg, German C; Forster, John W

    2017-01-04

    Symbiotic associations between tall fescue grasses and asexual Epichloë fungal endophytes exhibit biosynthesis of alkaloid compounds causing both beneficial and detrimental effects. Candidate novel endophytes with favourable chemotypic profiles have been identified in germplasm collections by screening for genetic diversity, followed by metabolite profile analysis in endogenous genetic backgrounds. A subset of candidates was subjected to genome survey sequencing to detect the presence or absence and structural status of known genes for biosynthesis of the major alkaloid classes. The capacity to produce specific metabolites was directly predictable from metabolic data. In addition, study of duplicated gene structure in heteroploid genomic constitutions provided further evidence for the origin of such endophytes. Selected strains were inoculated into meristem-derived callus cultures from specific tall fescue genotypes to perform isogenic comparisons of alkaloid profile in different host backgrounds, revealing evidence for host-specific quantitative control of metabolite production, consistent with previous studies. Certain strains were capable of both inoculation and formation of longer-term associations with a nonhost species, perennial ryegrass (Lolium perenne L.). Discovery and primary characterisation of novel endophytes by DNA analysis, followed by confirmatory metabolic studies, offers improvements of speed and efficiency and hence accelerated deployment in pasture grass improvement programs.

  5. Invasion of an asexual American water flea clone throughout Africa and rapid displacement of a native sibling species.

    Science.gov (United States)

    Mergeay, Joachim; Verschuren, Dirk; De Meester, Luc

    2006-11-22

    The huge ecological and economic impact of biological invasions creates an urgent need for knowledge of traits that make invading species successful and factors helping indigenous populations to resist displacement by invading species or genotypes. High genetic diversity is generally considered to be advantageous in both processes. Combined with sex, it allows rapid evolution and adaptation to changing environments. We combined paleogenetic analysis with continent-wide survey of genetic diversity at nuclear and mitochondrial loci to reconstruct the invasion history of a single asexual American water flea clone (hybrid Daphnia pulexxDaphnia pulicaria) in Africa. Within 60 years of the original introduction of this invader, it displaced the genetically diverse, sexual population of native D. pulex in Lake Naivasha (Kenya), despite a formidable numerical advantage of the local population and continuous replenishment from a large dormant egg bank. Currently, the invading clone has spread throughout the range of native African D. pulex, where it appears to be the only occurring genotype. The absence of genetic variation did not hamper either the continent-wide establishment of this exotic lineage or the effective displacement of an indigenous and genetically diverse sibling species.

  6. Enhancement of neutrophil-mediated killing of Plasmodium falciparum asexual blood forms by fatty acids: importance of fatty acid structure.

    Science.gov (United States)

    Kumaratilake, L M; Ferrante, A; Robinson, B S; Jaeger, T; Poulos, A

    1997-10-01

    Effects of fatty acids on human neutrophil-mediated killing of Plasmodium falciparum asexual blood forms were investigated by using a quantitative radiometric assay. The results showed that the antiparasitic activity of neutrophils can be greatly increased (>threefold) by short-term treatment with fatty acids with 20 to 24 carbon atoms and at least three double bonds. In particular, the n-3 polyenoic fatty acids, eicosapentaenoic and docosahexaenoic acids, and the n-6 fatty acid, arachidonic acid, significantly enhanced neutrophil antiparasitic activity. This effect was >1.5-fold higher than that induced by an optical concentration of the known agonist cytokine tumor necrosis factor alpha (TNF-alpha). At suboptimal concentrations, the combination of arachidonic acid and TNF-alpha caused a synergistic increase in neutrophil-mediated parasite killing. The fatty acid-induced effect was independent of the availability of serum opsonins but dependent on the structure of the fatty acids. The length of the carbon chain, degree of unsaturation, and availability of a free carboxyl group were important determinants of fatty acid activity. The fatty acids which increased neutrophil-mediated killing primed the enhanced superoxide radical generation of neutrophils in response to P. falciparum as detected by chemiluminescence. Scavengers of oxygen radicals significantly reduced the fatty acid-enhanced parasite killing, but cyclooxygenase and lipoxygenase inhibitors had no effect. These findings have identified a new class of immunoenhancers that could be exploited to increase resistance against Plasmodium species.

  7. Homogeneous population of the brown alga Sargassum polycystum in Southeast Asia: possible role of recent expansion and asexual propagation.

    Directory of Open Access Journals (Sweden)

    Sze Wai Chan

    Full Text Available Southeast Asia has been known as one of the biodiversity hotspots in the world. Repeated glacial cycles during Pleistocene were believed to cause isolation of marine taxa in refugia, resulting in diversification among lineages. Recently, ocean current was also found to be another factor affecting gene flow by restricting larval dispersal in animals. Macroalgae are unique in having mode of reproduction that differs from that of animals. Our study on the phylogeographical pattern of the brown macroalga Sargassum polycystum using nuclear Internal Transcribed Spacer 2 (ITS2, plastidal RuBisCO spacer (Rub spacer and mitochondrial cytochrome oxidase subunit-III (Cox3 as molecular markers revealed genetic homogeneity across 27 sites in Southeast Asia and western Pacific, in sharp contrast to that revealed from most animal studies. Our data suggested that S. polycystum persisted in single refugium during Pleistocene in a panmixia pattern. Expansion occurred more recently after the Last Glacial Maximum and recolonization of the newly flooded Sunda Shelf could have involved asexual propagation of the species. High dispersal ability through floating fronds carrying developing germlings may also contribute to the low genetic diversity of the species.

  8. Homogeneous population of the brown alga Sargassum polycystum in Southeast Asia: possible role of recent expansion and asexual propagation.

    Science.gov (United States)

    Chan, Sze Wai; Cheang, Chi Chiu; Chirapart, Anong; Gerung, Grevo; Tharith, Chea; Ang, Put

    2013-01-01

    Southeast Asia has been known as one of the biodiversity hotspots in the world. Repeated glacial cycles during Pleistocene were believed to cause isolation of marine taxa in refugia, resulting in diversification among lineages. Recently, ocean current was also found to be another factor affecting gene flow by restricting larval dispersal in animals. Macroalgae are unique in having mode of reproduction that differs from that of animals. Our study on the phylogeographical pattern of the brown macroalga Sargassum polycystum using nuclear Internal Transcribed Spacer 2 (ITS2), plastidal RuBisCO spacer (Rub spacer) and mitochondrial cytochrome oxidase subunit-III (Cox3) as molecular markers revealed genetic homogeneity across 27 sites in Southeast Asia and western Pacific, in sharp contrast to that revealed from most animal studies. Our data suggested that S. polycystum persisted in single refugium during Pleistocene in a panmixia pattern. Expansion occurred more recently after the Last Glacial Maximum and recolonization of the newly flooded Sunda Shelf could have involved asexual propagation of the species. High dispersal ability through floating fronds carrying developing germlings may also contribute to the low genetic diversity of the species.

  9. Virulence and Molecular Analyses Support Asexual Reproduction of Puccinia striiformis f. sp. tritici in the U.S. Pacific Northwest.

    Science.gov (United States)

    Cheng, P; Chen, X M

    2014-11-01

    Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, occurs every year and causes significant yield losses in the U.S. Pacific Northwest (PNW). A large number of P. striiformis f. tritici races are identified every year and predominant races have changed rapidly. Barberry and mahonia plants, which have been identified under controlled conditions as alternate hosts for the fungus, are found in the region. However, whether sexual reproduction occurs in the P. striiformis f. sp. tritici population under natural conditions is not clear. To determine the reproduction mode of the P. striiformis f. sp. tritici population using virulence and molecular markers, a systematic collection of leaf samples with a single stripe of uredia was made in 26 fields in the PNW in 2010. In total, 270 isolates obtained from the PNW collection, together with 66 isolates from 20 other states collected in the same year, were characterized by virulence tests and simple sequence repeat (SSR) markers. In total, 21 races and 66 multilocus genotypes (MLGs) were detected, of which 15 races and 32 MLGs were found in the PNW. Cluster analysis with the SSR marker data revealed two genetic groups, which were significantly correlated to the two virulence groups. The analyses of genotype/individual ratio, multilocus linkage disequilibrium, and heterozygosity strongly supported asexual reproduction for the pathogen population in the PNW, as well as other regions of the United States.

  10. FgFlbD regulates hyphal differentiation required for sexual and asexual reproduction in the ascomycete fungus Fusarium graminearum.

    Science.gov (United States)

    Son, Hokyoung; Kim, Myung-Gu; Chae, Suhn-Kee; Lee, Yin-Won

    2014-11-01

    Fusarium graminearum is a filamentous fungal plant pathogen that infects major cereal crops. The fungus produces both sexual and asexual spores in order to endure unfavorable environmental conditions and increase their numbers and distribution across plants. In a model filamentous fungus, Aspergillus nidulans, early induction of conidiogenesis is orchestrated by the fluffy genes. The objectives of this study were to characterize fluffy gene homologs involved in conidiogenesis and their mechanism of action in F. graminearum. We characterized five fluffy gene homologs in F. graminearum and found that FlbD is the only conserved regulator for conidiogenesis in A. nidulans and F. graminearum. Deletion of fgflbD prevented hyphal differentiation and the formation of perithecia. Successful interspecies complementation using A. nidulans flbD demonstrated that the molecular mechanisms responsible for FlbD functions are conserved in F. graminearum. Moreover, abaA-wetA pathway is positively regulated by FgFlbD during conidiogenesis in F. graminearum. Deleting fgflbD abolished morphological effects of abaA overexpression, which suggests that additional factors for FgFlbD or an AbaA-independent pathway for conidiogenesis are required for F. graminearum conidiation. Importantly, this study led to the construction of a genetic pathway of F. graminearum conidiogenesis and provides new insights into the genetics of conidiogenesis in fungi.

  11. Efficient production of bioactive metabolites from Antrodia camphorata ATCC 200183 by asexual reproduction-based repeated batch fermentation.

    Science.gov (United States)

    Li, Hua-Xiang; Lu, Zhen-Ming; Geng, Yan; Gong, Jin-Song; Zhang, Xiao-Juan; Shi, Jin-Song; Xu, Zheng-Hong; Ma, Yan-He

    2015-10-01

    Large-scale submerged fermentation (SmF) of Antrodia camphorata (A. camphorata) usually encounters challenges including tedious preparation of mycelial inoculum, long fermentation period (10-14 d), and poor repeatability. Here we developed an asexual reproduction-based repeated batch fermentation (RBF) process for bioactive metabolites production by A. camphorata ATCC 200183. Compared with traditional batch fermentation, production time was shortened to 58 d from 80 d (overall time for eight cycles) using the RBF process established in this study, and accordingly, the productivities of bioactive metabolites (including antrodins) were improved by 40-60%. Kinetic parameters (α is 2.1-18.7 times as β) indicated that the cell growth was the major contribution for bioactive metabolites production. The RBF shows excellent batch-repeatability (Pearson correlation coefficient of 0.998±0.001), together with advantages of energy-efficient, low cost, and labor-saving, RBF process can be implemented to SmF by other filamentous fungi.

  12. Regeneration and asexual reproduction share common molecular changes: upregulation of a neural glycoepitope during morphallaxis in Lumbriculus.

    Science.gov (United States)

    Martinez, Veronica G; Menger, Gus J; Zoran, Mark J

    2005-05-01

    Neural morphallaxis is a regenerative process characterized by wide-spread anatomical and physiological changes in an adult nervous system. During segmental regeneration of the annelid worm, Lumbriculus variegatus, neural morphallaxis involved a reorganization of sensory, interneuronal, and motor systems as posterior fragments gained a more anterior body position. A monoclonal antibody, Lan 3-2, which labels a neural glyco-domain in the leech, was reactive in Lumbriculus. In the worm, this antibody labeled neural structures, particularly axonal tracts and giant fiber pathways of the central nervous system. A 60kDa protein, possessing a lumbriculid mannose-rich glycoepitope, was upregulated during neural morphallaxis, peaking in its expression at 3 weeks post-amputation. Peak upregulation of the Lan 3-2 epitope, or the protein possessing it, corresponded to the time of major neurobehavioral plasticity during regeneration. Analyses of asexually reproducing animals also revealed induction of the Lan 3-2 epitope. In this developmental context, Lan 3-2 epitope upregulation was also confined to segments expressing both changes in positional identity and neurobehavioral plasticity, but these molecular and behavioral changes occurred prior to body fragmentation. These results suggest that the lumbriculid Lan 3-2 glycoepitope and proteins that bear them have been co-opted for neural morphallactic programs, induced both in anticipation of reproductive fragmentation and in compensation for injury-induced fragmentation.

  13. Evolution and architecture of the inner membrane complex in asexual and sexual stages of the malaria parasite.

    Science.gov (United States)

    Kono, Maya; Herrmann, Susann; Loughran, Noeleen B; Cabrera, Ana; Engelberg, Klemens; Lehmann, Christine; Sinha, Dipto; Prinz, Boris; Ruch, Ulrike; Heussler, Volker; Spielmann, Tobias; Parkinson, John; Gilberger, Tim W

    2012-09-01

    The inner membrane complex (IMC) is a unifying morphological feature of all alveolate organisms. It consists of flattened vesicles underlying the plasma membrane and is interconnected with the cytoskeleton. Depending on the ecological niche of the organisms, the function of the IMC ranges from a fundamental role as reinforcement system to more specialized roles in motility and cytokinesis. In this article, we present a comprehensive evolutionary analysis of IMC components, which exemplifies the adaptive nature of the IMCs' protein composition. Focusing on eight structurally distinct proteins in the most prominent "genus" of the Alveolata-the malaria parasite Plasmodium-we demonstrate that the level of conservation is reflected in phenotypic characteristics, accentuated in differential spatial-temporal patterns of these proteins in the motile stages of the parasite's life cycle. Colocalization studies with the centromere and the spindle apparatus reveal their discriminative biogenesis. We also reveal that the IMC is an essential structural compartment for the development of the sexual stages of Plasmodium, as it seems to drive the morphological changes of the parasite during the long and multistaged process of sexual differentiation. We further found a Plasmodium-specific IMC membrane matrix protein that highlights transversal structures in gametocytes, which could represent a genus-specific structural innovation required by Plasmodium. We conclude that the IMC has an additional role during sexual development supporting morphogenesis of the cell, which in addition to its functions in the asexual stages highlights the multifunctional nature of the IMC in the Plasmodium life cycle.

  14. Focal fits during chlorambucil therapy

    Science.gov (United States)

    Naysmith, A.; Robson, R. H.

    1979-01-01

    An elderly man receiving chlorambucil for chronic lymphatic leukaemia developed focal fits. The onset and frequency were dose related. There was no evidence of metabolic disturbance or of meningeal leukaemia. Although reported in children and well recognized in animals, chlorambucil-induced fits in an adult have not been previously recorded. PMID:118440

  15. Optimization of military garment fit

    NARCIS (Netherlands)

    Daanen, H.A.M.

    2014-01-01

    In the Dutch armed forces clothing sizes are determined using 3D body scans. To evaluate if the predicted size based on the scan analysis matches the best fit, 35 male soldiers fitted a combat jacket and combat pants. It was shown that the predicted jacket size was slightly too large. Therefore, an

  16. Reeling of tight fit pipe

    NARCIS (Netherlands)

    Focke, E.S.

    2007-01-01

    If it would be possible to install Tight Fit Pipe by means of reeling, it would be an attractive new option for the exploitation of offshore oil and gas fields containing corrosive hydrocarbons. Tight Fit Pipe is a mechanically bonded double walled pipe where a corrosion resistant alloy liner pipe

  17. Definitions of Health Terms: Fitness

    Science.gov (United States)

    ... this page: https://medlineplus.gov/definitions/fitnessdefinitions.html Definitions of Health Terms: Fitness To use the sharing features on ... the most of your exercise routine. Find more definitions on Fitness | General Health | Minerals | Nutrition | Vitamins Activity Count Physical activity is ...

  18. ProFit: Bayesian Profile Fitting of Galaxy Images

    CERN Document Server

    Robotham, A S G; Tobar, R; A,; Moffett,; Driver, S P

    2016-01-01

    We present ProFit, a new code for Bayesian two-dimensional photometric galaxy profile modelling. ProFit consists of a low-level C++ library (libprofit), accessible via a command-line interface and documented API, along with high-level R (ProFit) and Python (PyProFit) interfaces (available at github.com/ICRAR/ libprofit, github.com/ICRAR/ProFit, and github.com/ICRAR/pyprofit respectively). R ProFit is also available pre-built from CRAN, however this version will be slightly behind the latest GitHub version. libprofit offers fast and accurate two- dimensional integration for a useful number of profiles, including Sersic, Core-Sersic, broken-exponential, Ferrer, Moffat, empirical King, point-source and sky, with a simple mechanism for adding new profiles. We show detailed comparisons between libprofit and GALFIT. libprofit is both faster and more accurate than GALFIT at integrating the ubiquitous Serrsic profile for the most common values of the Serrsic index n (0.5 < n < 8). The high-level fitting code Pr...

  19. Female Fitness in the Blogosphere

    Directory of Open Access Journals (Sweden)

    Jesper Andreasson

    2013-07-01

    Full Text Available This article analyzes self-portrayals and gender constructions among female personal trainers within an Internet-mediated framework of fitness culture. The empirical material comes from a close examination of three strategically selected blogs. The result shows that some of the blogs clearly build upon what Connell calls emphasized femininity, as a means of legitimizing and constructing appropriate female fitness. In addition, there are also tendencies of sexualization in text and imagery present. As such, these self-representations are framed within a cultural history of body fitness dominated by stereotypical ways of perceiving masculinity and femininity. However, this does not capture the entire presentation of the self among the analyzed fitness bloggers. The blogs also point in the direction of ongoing negotiations and subversions of traditional gender norms. Among other things, they show how irony and humor are used as a means of questioning normative gender constructions while empowering female fitness and bodyliness.

  20. Marginal coral populations: the densest known aggregation of Pocillopora in the Galápagos Archipelago is of asexual origin

    Directory of Open Access Journals (Sweden)

    Iliana B Baums

    2014-11-01

    Full Text Available Coral populations at distributional margins frequently experience suboptimal and variable conditions. Recurrent El Niño-Southern Oscillation (ENSO warming events have caused extensive mortality of reef-building corals in the Eastern Pacific, and particularly impacted branching pocilloporid corals in the Galápagos Islands. Pocillopora spp. were previously more common and formed incipient reefs at several locations in the Archipelago but now occur as scattered colonies. Here, we report an unusually concentrated aggregation of colonies and evaluate their current genetic diversity. In particular we focus on a large population of 1614 live Pocillopora colonies found in a volcanic lagoon along the southern shore of Isabela Island. Forty seven colonies were sampled, primarily using a spatially explicit sampling design, and all colonies belonged to Pocillopora mitochondrial open reading frame lineage type 3a. Typing of additional Pocillopora samples (n = 40 from three other islands indicated that this stand is the only known representative of type 3a in the Galápagos Islands. The Isabela Pocillopora type 3a colonies harbored Symbiodinium ITS-2 clade C1d. Multilocus genotyping (n = 6 microsatellites capable of resolving individual clones indicated that this stand is monogenotypic and thus the high density of colonies is a result of asexual reproduction, likely via fragmentation. Colony size distribution, while imperfect, suggested the stand regrew from remnant colonies that survived the 1997/98 ENSO event but may postdate the 1982/83 ENSO. The community of Pocillopora colonies at Isabela is of particular ecological value due to its high density and support of associated organisms such as fish and benthic invertebrates. The Galapagos Pocillopora corals will continue to provide insights into the genetic structure and population dynamics of marginal coral populations.

  1. Environmental control of asexual reproduction and somatic growth of Aurelia spp. (Cnidaria, Scyphozoa) polyps from the Adriatic Sea.

    Science.gov (United States)

    Hubot, Nathan; Lucas, Cathy H; Piraino, Stefano

    2017-01-01

    Polyps of two moon jellyfish species, Aurelia coerulea and A. relicta, from two Adriatic Sea coastal habitats were incubated under multiple combinations of temperature (14, 21°C), salinity (24, 37 ppt) and food regime (9.3, 18.6, 27.9 μg C ind-1 week-1) to comparatively assess how these factors may influence major asexual reproduction processes in the two species. Both species exhibited a shared pattern of budding mode (Directly Budded Polyps: DBP; Stolonal Budded Polyps: SBP), with DBP favoured under low food supply (9.3 μg C ind -1 week-1) and low temperature (14°C), and SBP dominant under high temperature (21°C). However, A. coerulea showed an overall higher productivity than A. relicta, in terms of budding and podocyst production rates. Further, A. coerulea exhibited a wide physiological plasticity across different temperatures and salinities as typical adaptation to ecological features of transitional coastal habitats. This may support the hypothesis that the invasion of A. coerulea across coastal habitats worldwide has been driven by shellfish aquaculture, with scyphistoma polyps and resting stages commonly found on bivalve shells. On the contrary, A. relicta appears to be strongly stenovalent, with cold, marine environmental optimal preferences (salinity 37 ppt, T ranging 14-19°C), corroborating the hypothesis of endemicity within the highly peculiar habitat of the Mljet lake. By exposing A. relicta polyps to slightly higher temperature (21°C), a previously unknown developmental mode was observed, by the sessile polyp regressing into a dispersive, temporarily unattached and tentacle-less, non-feeding stage. This may allow A. relicta polyps to escape climatic anomalies associated to warming of surface layers and deepening of isotherms, by moving into deeper, colder layers. Overall, investigations on species-specific eco-physiological and ontogenetic potentials of polyp stages may contribute to clarify the biogeographic distribution of jellyfish and the

  2. Population genetic structure of Titanotrichum oldhamii (Gesneriaceae), a subtropical bulbiliferous plant with mixed sexual and asexual reproduction.

    Science.gov (United States)

    Wang, Chun-neng; Moller, Michael; Cronk, Quentin C B

    2004-02-01

    Titanotrichum oldhamii is a monotypic genus distributed in Taiwan, adjacent regions of China and the Ryukyu Isands of Japan. Its conservation status is vulnerable as most populations are small and widely scattered. Titanotrichum has a mixed system of reproduction with vegetative bulbils and seeds. The aim of this study was to understand the population genetic structure of Titanotrichum in relation to its specific reproductive behaviour and to determine possible implications for conservation strategies. After an extensive inventory of most wild populations of Titanotrichum in East Asia, samples from 25 populations within its major distribution were carried out utilizing RAPD and inter-SSR molecular fingerprinting analysis. The findings support the conclusion that many populations reproduce predominantly asexually but that some genetic variation still exists within populations. However, significant amounts of variation exist between populations, perhaps reflecting population differentiation by drift. This partitioning of genetic diversity indicates that the level of inter-population gene exchange is extremely low. These findings are consistent with field observations of very limited seed production. The Chinese populations are similar to those of Northern Taiwan, while the Ryukyu populations fall within the range of variation of the north-central Taiwan populations. The Taiwanese populations are relatively variable and differentiation between north, east and south Taiwan is evident. The distribution of Titanotrichum seems to be consistent with a former land connection between China, Taiwan and the Ryukyu Islands at a glacial maximum during the Quaternary, followed by progressive fragmentation of the populations. North-central Taiwan is the centre of genetic diversity, possibly due to the proximity of the former land bridge between the regions, together with the variety of suitable habitats in north Taiwan. The significance of these findings for conservation is

  3. Influences of Different Habitats on Asexual Propagation of Wild Gastrodia elata f. glauca being Domesticated in Ganzi

    Institute of Scientific and Technical Information of China (English)

    Xueqiang XIE

    2015-01-01

    Objective] The influences of different habitats on asexual propagation of wild Geg (abbreviation for Gastrodia elata Bl. f. glauca S. Chow) being domesticat-ed in Ganzi prefecture was studied. [Method] The research trial was carried out in the fol owing three kinds of habitats at the same time: the plastic greenhouses, the birch forest of shady slope and the shrubbery of sunny slope, and the results were analyzed with group data average hypothesis test method. [Result] The overal tuber (the juvenile tuber, the immature tuber and the mature tuber) yield and the mature tuber yield were both very significantly higher in the plastic greenhouses than in the other two types of habitats, and respectively reached 9.52 and 6.70 kg/m2; the ma-ture tuber drying rate was dramatical y or very dramatical y lower in the plastic greenhouses than in the other two types of habitats, and was 23.84%; the stabilities of the overal tuber yield, the mature tuber yield and the drying rate were al re-duced in the order of greenhouses, birch forest and shrubbery; and the dry mature tuber yield of the plastic greenhouses was the highest in the three kinds of habi-tats, and was 1.60 kg/m2. [Conclusion] A good habitat had to be created or chosen in the domesticating cultivation of the wild Geg in Ganzi prefecture. The preferred choice was the plastic greenhouse, the alternative one was the deciduous broad-leaved forest of shady slope. The imitating wild planting of the wild Geg should be done in the warm moist deciduous broad-leaved forest of shady slope.

  4. Aspergillus asexual reproduction and sexual reproduction are differentially affected by transcriptional and translational mechanisms regulating stunted gene expression.

    Science.gov (United States)

    Wu, J; Miller, B L

    1997-10-01

    The Stunted protein (StuAp) is a member of a family of transcription factors that regulate fungal development and cell cycle progression. Regulated stuA gene expression is required for correct cell pattern formation during asexual reproduction (conidiation) and for initiation of the sexual reproductive cycle in Aspergillus nidulans. Transcriptional initiation from two different promoters yields overlapping mRNAs (stuA alpha and stuAbeta) that upon translation yield the same protein. Here we show that multiple regulatory mechanisms interact to control (i) developmental competence-dependent expression of both transcripts and (ii) induction-dependent expression of stuA alpha, but not stuAbeta, by the conidiation-specific Bristle (BrlAp) transcriptional activator. Quantitative levels of both mRNAs are further modulated by (i) an activator(s) located at a far-upstream upstream activation sequence, (ii) feedback regulation by StuAp, and (iii) positive translational regulation that requires the peptide product of a micro-open reading frame unique to the stuA alpha mRNA 5' untranslated region. Gradients in stuA alpha expression were most important for correct cell and tissue type development. Threshold requirements were as follows: metula-phialide differentiation < ascosporogenesis < cleistothecial shell-Hülle cell differentiation. Altered stuA expression affected conidiophore morphology and conidial yields quantitatively but did not alter the temporal development of cell types or conidiophore density. By contrast, the sexual cycle showed both temporal delay and quantitative reduction in the number of cleistothecial initials but normal morphogenesis of tissue types.

  5. The 'mother of thousands' (Kalanchoë daigremontiana): a plant model for asexual reproduction and CAM studies.

    Science.gov (United States)

    Garcês, Helena; Sinha, Neelima

    2009-10-01

    The genus Kalanchoë plays an important role in the investigation of biochemical, physiological and phylogenetic aspects of Crassulacean acid metabolism (CAM) in plants, which is an important evolutionary adaptation of the photosynthetic carbon assimilation pathway to arid environments. In addition, natural compounds extracted from tissues of Kalanchoë have potential applicability in treating tumors and inflammatory and allergic diseases, and have been shown to have insecticidal properties. Kalanchoë daigremontiana (Hamet & Perrier) originated in Madagascar and reproduces asexually by spontaneously forming whole plantlets on leaves. Plantlets develop symmetrically along the leaf margins on leaf notches, closely resembling zygotic embryos in development, and once the root system is formed, they detach from the mother-leaf, fall to the ground, and grow into new plants. This phenomenon is also found in other species from this same genus; however, the formation of leaf-plantlets is variable among species. Nevertheless, all species illustrate the remarkable ability of plant somatic cells to regenerate an entire organism, which has fascinated the scientific community for many years. It was only recently that the morphogenic process involved in the origin of K. daigremontiana plantlets was determined using molecular and genetic tools: K. daigremontiana forms plantlets by co-opting both organogenesis and embryogenesis programs into leaves. The ability of K. daigremontiana species to form somatic embryos outside of a seed environment provides an attractive model system to study somatic embryogenesis in nature, particularly the molecular mechanism involved in the acquisition of competence by vegetative cells to make embryos without fertilization.

  6. Colonization history and clonal richness of asexual Daphnia in periglacial habitats of contrasting age in West Greenland.

    Science.gov (United States)

    Haileselasie, Tsegazeabe H; Mergeay, Joachim; Weider, Lawrence J; Jeppesen, Erik; De Meester, Luc

    2016-07-01

    Due to climate change, Arctic ice sheets are retreating. This leads to the formation of numerous new periglacial ponds and lakes, which are being colonized by planktonic organisms such as the water flea Daphnia. This system provides unique opportunities to test genotype colonization dynamics and the genetic assemblage of populations. Here, we studied clonal richness of the Daphnia pulex species complex in novel periglacial habitats created by glacial retreat in the Jakobshavn Isbrae area of western Greenland. Along a 10 km transect, we surveyed 73 periglacial habitats out of which 61 were colonized by Daphnia pulex. Hence, for our analysis, we used 21 ponds and 40 lakes in two clusters of habitats differing in age (estimated 150 years). We tested the expectation that genetic diversity would be low in recently formed (i.e. young), small habitats, but would increase with increasing age and size. We identified a total of 42 genetically distinct clones belonging to two obligately asexual species of the D. pulex species complex: D. middendorffiana and the much more abundant D. pulicaria. While regional clonal richness was high, most clones were rare: 16 clones were restricted to a single habitat and the five most widespread clones accounted for 68% of all individuals sampled. On average, 3·2 clones (range: 1-12) coexisted in a given pond or lake. There was no relationship between clonal richness and habitat size when we controlled for habitat age. Whereas clonal richness was statistically higher in the cluster of older habitats when compared with the cluster of younger ponds and lakes, most young habitats were colonized by multiple genotypes. Our data suggest that newly formed (periglacial) ponds and lakes are colonized within decades by multiple genotypes via multiple colonization events, even in the smallest of our study systems (4 m(2) ).

  7. AKLSQF - LEAST SQUARES CURVE FITTING

    Science.gov (United States)

    Kantak, A. V.

    1994-01-01

    The Least Squares Curve Fitting program, AKLSQF, computes the polynomial which will least square fit uniformly spaced data easily and efficiently. The program allows the user to specify the tolerable least squares error in the fitting or allows the user to specify the polynomial degree. In both cases AKLSQF returns the polynomial and the actual least squares fit error incurred in the operation. The data may be supplied to the routine either by direct keyboard entry or via a file. AKLSQF produces the least squares polynomial in two steps. First, the data points are least squares fitted using the orthogonal factorial polynomials. The result is then reduced to a regular polynomial using Sterling numbers of the first kind. If an error tolerance is specified, the program starts with a polynomial of degree 1 and computes the least squares fit error. The degree of the polynomial used for fitting is then increased successively until the error criterion specified by the user is met. At every step the polynomial as well as the least squares fitting error is printed to the screen. In general, the program can produce a curve fitting up to a 100 degree polynomial. All computations in the program are carried out under Double Precision format for real numbers and under long integer format for integers to provide the maximum accuracy possible. AKLSQF was written for an IBM PC X/AT or compatible using Microsoft's Quick Basic compiler. It has been implemented under DOS 3.2.1 using 23K of RAM. AKLSQF was developed in 1989.

  8. Opas CrossFit -harjoitteluun

    OpenAIRE

    Knaapi, Matti

    2014-01-01

    CrossFit on laji, joka pyrkii edistämään terveyttä ja kuntoa. CrossFit saleja löytyy mailmalta yli 10 000 kappaletta. CrossFit -harjoittelussa pyritään parantamaan ihmisen kuntoa mahdollisimman laajalla skaalalla kehittämällä mm. voimaa, kestävyyttä, tarkkuutta, tasapainoa ja eri aineenvaihduntareittejä samanaikaisesti. Terveyden ja kunnon kehittämiseen kuuluu kuntoilun lisäksi myös muita osa-alueita. Ruokavalio ja kehonhuolto ovat tärkeitä osa-alueita hyvän kunnon saavuttamiseksi. Ruokav...

  9. Opas CrossFit -harjoitteluun

    OpenAIRE

    Knaapi, Matti

    2014-01-01

    CrossFit on laji, joka pyrkii edistämään terveyttä ja kuntoa. CrossFit saleja löytyy mailmalta yli 10 000 kappaletta. CrossFit -harjoittelussa pyritään parantamaan ihmisen kuntoa mahdollisimman laajalla skaalalla kehittämällä mm. voimaa, kestävyyttä, tarkkuutta, tasapainoa ja eri aineenvaihduntareittejä samanaikaisesti. Terveyden ja kunnon kehittämiseen kuuluu kuntoilun lisäksi myös muita osa-alueita. Ruokavalio ja kehonhuolto ovat tärkeitä osa-alueita hyvän kunnon saavuttamiseksi. Ruokav...

  10. The fitness value of information

    CERN Document Server

    Bergstrom, Carl T

    2007-01-01

    Biologists measure information in different ways. Neurobiologists and researchers in bioinformatics often measure information using information-theoretic measures such as Shannon's entropy or mutual information. Behavioral biologists and evolutionary ecologists more commonly use decision-theoretic measures, such the value of information, which assess the worth of information to a decision maker. Here we show that these two kinds of measures are intimately related in the context of biological evolution. We present a simple model of evolution in an uncertain environment, and calculate the increase in Darwinian fitness that is made possible by information about the environmental state. This fitness increase -- the fitness value of information -- is a composite of both Shannon's mutual information and the decision-theoretic value of information. Furthermore, we show that in certain cases the fitness value of responding to a cue is exactly equal to the mutual information between the cue and the environment. In gen...

  11. Strength Training: For Overall Fitness

    Science.gov (United States)

    ... Accessed Jan. 11, 2016. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: Guidance for prescribing exercise. American College of ...

  12. Dance Your Way to Fitness

    Science.gov (United States)

    ... Better heart health Stronger muscles Better balance and coordination Stronger bones Lower risk of dementia Improved memory Reduced stress More energy Improved mood Types of Dance There are dance styles to fit almost anyone ...

  13. Kinematic Fitting of Detached Vertices

    Energy Technology Data Exchange (ETDEWEB)

    Mattione, Paul [Rice Univ., Houston, TX (United States)

    2007-05-01

    The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

  14. Flow cytometric readout based on Mitotracker Red CMXRos staining of live asexual blood stage malarial parasites reliably assesses antibody dependent cellular inhibition

    DEFF Research Database (Denmark)

    Jogdand, Prajakta S; Singh, Susheel K; Christiansen, Michael;

    2012-01-01

    ABSTRACT: BACKGROUND: Functional in vitro assays could provide insights into the efficacy of malaria vaccine candidates. For estimating the anti-parasite effect induced by a vaccine candidate, an accurate determination of live parasite count is an essential component of most in vitro bioassays...... asynchronous and tightly synchronized asexual blood stage cultures of Plasmodium falciparum were stained with CMXRos and subjected to detection by flow cytometry and fluorescence microscopy. The parasite counts obtained by flow cytometry were compared to standard microscopic counts obtained through examination...

  15. Sexual and asexual reproduction in Didemnum rodriguesi (Ascidiacea, Didemnidae Reprodução sexuada e assexuada em Didemnum rodriguesi (Ascidiacea, Didemnidae

    Directory of Open Access Journals (Sweden)

    Nicole F. Ritzmann

    2009-03-01

    Full Text Available Sexual and asexual reproduction and associated population dynamics were investigated in the colonial ascidian Didemnum rodriguesi Rocha & Monniot, 1993 (Didemnidae in southern Brazil. Investment in sexual (production of new individuals and asexual (colony growth reproduction was compared between seasons. Permanently marked quadrats were repeatedly photographed to measure changes in colonies. Eggs and larvae were counted monthly in collected colonies. This species alternates seasonally between sexual (summer and asexual (winter reproduction. In summer, colonies were smaller, brooded eggs and larvae and recruitment rates were greater, while in winter, colony size was larger and eggs and larvae were absent. There is a relationship between fecundity and colony area. Fragmentation and fusion of colonies were similar in summer and winter, as well as mortality. In conclusion, D. rodriguesi has a lifecycle usual for high latitude ascidians with a limited time length for sexual reproduction and alternate investment in sexual and asexual reproduction along the year.Reprodução sexuada e assexuada, mortalidade e a dinâmica de fusões e fissões de colônias de Didemnum rodriguesi Rocha & Monniot, 1993 foram investigados e comparados no sul do Brasil, no inverno e verão. Tais eventos foram analisados por fotografias de áreas permanentemente demarcadas e coletas mensais de colônias. Os resultados indicam que esta espécie alterna sazonalmente a reprodução sexuada (verão e assexuada (inverno. Durante o verão as colônias são mais abundantes e menores, com ovos e larvas incubados e taxas de recrutamento maiores. No inverno há um menor número de colônias, porém de maior tamanho e inférteis. Existe uma relação entre fecundidade e tamanho da colônia. Não foram encontradas diferenças estatísticas no número de eventos de fragmentação e fusão entre o verão e inverno, bem como para mortalidade. Conclui-se que esta espécie tem um ciclo de

  16. Morfología vegetativa y reproducción asexual de Draparnaldia mutabilis (Chaetophoraceae, Chlorophyta), primer registro fundamentado para Argentina

    OpenAIRE

    Karina M. Michetti; Leonardi, Patricia I.; Eduardo J. Cáceres

    2007-01-01

    Draparnaldia mutabilis posee un talo compuesto por un sistema rizoidal postrado reducido y un sistema erguido que muestra una marcada diferenciación entre filamentos axiales y laterales, estos últimos agrupados en fascículos densos, altamente ramificados. La reproducción asexual ocurre por medio de zoósporas que poseen un patrón de germinación erguido. El registro de esta especie constituye la primera cita cierta para la República Argentina. Se presenta además, una clave con las e...

  17. Physical Fitness in the Army

    Science.gov (United States)

    1977-03-17

    situations, deal with the day to day duty demands, and maintain a trim physical appearance. But if it has been years since you exercised , do not run right...how much exercise is required to achieve and maintain a fit unit and secondly, how is this fitness requirement modified by age and sex . The Training...as the activity in which you are involved becomes easier, increase the amount. You can do 7 this by varying the intensity (how hard you exercise as

  18. Implementation of Health Fitness Exercise Programs.

    Science.gov (United States)

    Cundiff, David E., Ed.

    This monograph includes the following articles to aid in implementation of fitness concepts: (1) "Trends in Physical Fitness: A Personal Perspective" (H. Harrison Clarke); (2) "A Total Health-Fitness Life-Style" (Steven N. Blair); (3) "Objectives for the Nation--Physical Fitness and Exercise" (Jack H. Wilmore); (4) "A New Physical Fitness Test"…

  19. Ligand fitting with CCP4

    Science.gov (United States)

    2017-01-01

    Crystal structures of protein–ligand complexes are often used to infer biology and inform structure-based drug discovery. Hence, it is important to build accurate, reliable models of ligands that give confidence in the interpretation of the respective protein–ligand complex. This paper discusses key stages in the ligand-fitting process, including ligand binding-site identification, ligand description and conformer generation, ligand fitting, refinement and subsequent validation. The CCP4 suite contains a number of software tools that facilitate this task: AceDRG for the creation of ligand descriptions and conformers, Lidia and JLigand for two-dimensional and three-dimensional ligand editing and visual analysis, Coot for density interpretation, ligand fitting, analysis and validation, and REFMAC5 for macromolecular refinement. In addition to recent advancements in automatic carbohydrate building in Coot (LO/Carb) and ligand-validation tools (FLEV), the release of the CCP4i2 GUI provides an integrated solution that streamlines the ligand-fitting workflow, seamlessly passing results from one program to the next. The ligand-fitting process is illustrated using instructive practical examples, including problematic cases such as post-translational modifications, highlighting the need for careful analysis and rigorous validation. PMID:28177312

  20. 薄壳山核桃无性繁殖技术研究进展%Research Progress of Asexual Propagation Techniques of Carya illinoensis

    Institute of Scientific and Technical Information of China (English)

    李俊南; 李莲芳; 熊新武; 陈宏伟; 习学良

    2012-01-01

    综述了薄壳山核桃无性繁殖技术的研究进展,指出薄壳山核桃是国外引进的高档干果树种和特色新产业.薄壳山核桃无性繁殖技术研究现状包括砧木培育,嫁接技术及影响嫁接成活的因素,扦插繁殖,分株繁殖等栽培研究现状,提出目前薄壳山核桃无性繁殖存在的问题,旨在为薄壳山核桃的良种繁育提供参考.%The research progress of Carya illinoensis asexual propagation technology was summarized. The research status of asexual propagation technique Of Carya illinoensis include rootstock cultivation, grafting techniques and influencing factors, cutting propagation, division propagation. The main existing problems were put forward, so as to provide reference for fine variety breeding of Carya illinoensis.

  1. Co-evolutionary patterns and diversification of ant-fungus associations in the asexual fungus-farming ant Mycocepurus smithii in Panama.

    Science.gov (United States)

    Kellner, K; Fernández-Marín, H; Ishak, H D; Sen, R; Linksvayer, T A; Mueller, U G

    2013-06-01

    Partner fidelity through vertical symbiont transmission is thought to be the primary mechanism stabilizing cooperation in the mutualism between fungus-farming (attine) ants and their cultivated fungal symbionts. An alternate or additional mechanism could be adaptive partner or symbiont choice mediating horizontal cultivar transmission or de novo domestication of free-living fungi. Using microsatellite genotyping for the attine ant Mycocepurus smithii and ITS rDNA sequencing for fungal cultivars, we provide the first detailed population genetic analysis of local ant-fungus associations to test for the relative importance of vertical vs. horizontal transmission in a single attine species. M. smithii is the only known asexual attine ant, and it is furthermore exceptional because it cultivates a far greater cultivar diversity than any other attine ant. Cultivar switching could permit the ants to re-acquire cultivars after garden loss, to purge inferior cultivars that are locally mal-adapted or that accumulated deleterious mutations under long-term asexuality. Compared to other attine ants, symbiont choice and local adaptation of ant-fungus combinations may play a more important role than partner-fidelity feedback in the co-evolutionary process of M. smithii and its fungal symbionts.

  2. Effects of Cd, Co, Cu, Ni and Zn on asexual reproduction and early development of the tropical sea anemone Aiptasia pulchella.

    Science.gov (United States)

    Howe, Pelli L; Reichelt-Brushett, Amanda J; Clark, Malcolm W

    2014-11-01

    Currently few studies present sub-lethal toxicity data for tropical marine species, and there are no routine toxicity tests using marine cnidarians. The symbiotic sea anemone Aiptasia pulchella has been identified as a useful species for ecotoxicological risk assessment, and would provide a tropical marine cnidarian representative. Chronic sub-lethal toxicity tests assessing the effects of 28-day trace metal exposure on asexual reproduction in A. pulchella were investigated, and concentration-dependant reductions in the number of offspring that were produced were evident for all metal exposures. Metal concentration estimates causing 50% reductions in the numbers of asexually-reproduced juveniles after 28-day exposures (28-day effect concentrations 50%: EC50s) were 14 µg/L for copper, 63 µg/L for zinc, 107 µg/L for cobalt, 145 µg/L for cadmium, and 369 µg/L for nickel. Slightly higher 28-day EC50s of 16 µg/L for copper, 192 µg/L for zinc, 172 µg/L for cobalt, 185 µg/L for cadmium, and 404 µg/L for nickel exposures and were estimated based on reductions in the total number of live developed and undeveloped offspring. These sensitive and chronic sub-lethal toxicity estimates help fill the knowledge gap related to metal effects on cnidarians over longer exposure periods, and this newly-developed bioassay may provide a much needed tool for ecotoxicological risk assessment relevant to tropical marine environments.

  3. The HEX1 gene of Fusarium graminearum is required for fungal asexual reproduction and pathogenesis and for efficient viral RNA accumulation of Fusarium graminearum virus 1.

    Science.gov (United States)

    Son, Moonil; Lee, Kyung-Mi; Yu, Jisuk; Kang, Minji; Park, Jin Man; Kwon, Sun-Jung; Kim, Kook-Hyung

    2013-09-01

    The accumulation of viral RNA depends on many host cellular factors. The hexagonal peroxisome (Hex1) protein is a fungal protein that is highly expressed when the DK21 strain of Fusarium graminearum virus 1 (FgV1) infects its host, and Hex1 affects the accumulation of FgV1 RNA. The Hex1 protein is the major constituent of the Woronin body (WB), which is a peroxisome-derived electron-dense core organelle that seals the septal pore in response to hyphal wounding. To clarify the role of Hex1 and the WB in the relationship between FgV1 and Fusarium graminearum, we generated targeted gene deletion and overexpression mutants. Although neither HEX1 gene deletion nor overexpression substantially affected vegetative growth, both changes reduced the production of asexual spores and reduced virulence on wheat spikelets in the absence of FgV1 infection. However, the vegetative growth of deletion and overexpression mutants was increased and decreased, respectively, upon FgV1 infection compared to that of an FgV1-infected wild-type isolate. Viral RNA accumulation was significantly decreased in deletion mutants but was significantly increased in overexpression mutants compared to the viral RNA accumulation in the virus-infected wild-type control. Overall, these data indicate that the HEX1 gene plays a direct role in the asexual reproduction and virulence of F. graminearum and facilitates viral RNA accumulation in the FgV1-infected host fungus.

  4. Sponge budding is a spatiotemporal morphological patterning process: Insights from synchrotron radiation-based x-ray microtomography into the asexual reproduction of Tethya wilhelma

    Directory of Open Access Journals (Sweden)

    Nickel Michael

    2009-09-01

    Full Text Available Abstract Background Primary agametic-asexual reproduction mechanisms such as budding and fission are present in all non-bilaterian and many bilaterian animal taxa and are likely to be metazoan ground pattern characters. Cnidarians display highly organized and regulated budding processes. In contrast, budding in poriferans was thought to be less specific and related to the general ability of this group to reorganize their tissues. Here we test the hypothesis of morphological pattern formation during sponge budding. Results We investigated the budding process in Tethya wilhelma (Demospongiae by applying 3D morphometrics to high resolution synchrotron radiation-based x-ray microtomography (SR-μCT image data. We followed the morphogenesis of characteristic body structures and identified distinct morphological states which indeed reveal characteristic spatiotemporal morphological patterns in sponge bud development. We discovered the distribution of skeletal elements, canal system and sponge tissue to be based on a sequential series of distinct morphological states. Based on morphometric data we defined four typical bud stages. Once they have reached the final stage buds are released as fully functional juvenile sponges which are morphologically and functionally equivalent to adult specimens. Conclusion Our results demonstrate that budding in demosponges is considerably more highly organized and regulated than previously assumed. Morphological pattern formation in asexual reproduction with underlying genetic regulation seems to have evolved early in metazoans and was likely part of the developmental program of the last common ancestor of all Metazoa (LCAM.

  5. Mutation of FVS1, encoding a protein with a sterile alpha motif domain, affects asexual reproduction in the fungal plant pathogen Fusarium oxysporum.

    Science.gov (United States)

    Iida, Yuichiro; Fujiwara, Kazuki; Yoshioka, Yosuke; Tsuge, Takashi

    2014-02-01

    Fusarium oxysporum produces three kinds of asexual spores: microconidia, macroconidia and chlamydospores. We previously analysed expressed sequence tags during vegetative growth and conidiation in F. oxysporum and found 42 genes that were markedly upregulated during conidiation compared to vegetative growth. One of the genes, FVS1, encodes a protein with a sterile alpha motif (SAM) domain, which functions in protein-protein interactions that are involved in transcriptional or post-transcriptional regulation and signal transduction. Here, we made FVS1-disrupted mutants from the melon wilt pathogen F. oxysporum f. sp. melonis. Although the mutants produced all three kinds of asexual spores with normal morphology, they formed markedly fewer microconidia and macroconidia than the wild type. The mutants appeared to have a defect in the development of the conidiogenesis cells, conidiophores and phialides, required for the formation of microconidia and macroconidia. In contrast, chlamydospore formation was dramatically promoted in the mutants. The growth rates of the mutants on media were slightly reduced, indicating that FVS1 is also involved in, but not essential for, vegetative growth. We also observed that mutation of FVS1 caused defects in conidial germination and virulence, suggesting that the Fvs1 has pleiotropic functions in F. oxysporum.

  6. Desirable design of hose fittings

    DEFF Research Database (Denmark)

    Voigt, Kristian

    1998-01-01

    This paper describes the primary functionality of a hose fitting. There has been made a discussion about the different parts of the hose assembly - the nipple, the hose and the outer compression parts. The last subject covered is which criteria should be put up for determining what is a good hose...... fittings. There has been made an uncompleted list of 'Voice of Customer' to this respect. Observations and interviews in industry should expand this list.......This paper describes the primary functionality of a hose fitting. There has been made a discussion about the different parts of the hose assembly - the nipple, the hose and the outer compression parts. The last subject covered is which criteria should be put up for determining what is a good hose...

  7. Accelerated Fitting of Stellar Spectra

    CERN Document Server

    Ting, Yuan-Sen; Rix, Hans-Walter

    2016-01-01

    Stellar spectra are often modeled and fit by interpolating within a rectilinear grid of synthetic spectra to derive the stars' labels: stellar parameters and elemental abundances. However, the number of synthetic spectra needed for a rectilinear grid grows exponentially with the label space dimensions, precluding the simultaneous and self-consistent fitting of more than a few elemental abundances. Shortcuts such as fitting subsets of parameters separately can introduce unknown systematics and do not produce correct error covariances in the derived labels. In this paper we present a new approach -- CHAT (Convex Hull Adaptive Tessellation) -- which includes several new ideas for inexpensively generating a sufficient stellar synthetic library, using linear algebra and the concept of an adaptive, data-driven grid. A convex hull approximates the region where the data lie in the label space. A variety of tests with mock datasets demonstrate that CHAT can reduce the number of required synthetic model calculations by...

  8. Fitness Doping and Body Management

    DEFF Research Database (Denmark)

    Thualagant, Nicole

    This PhD thesis examines in a first paper the conceptualization of fitness doping and its current limitations. Based on a review of studies on bodywork and fitness doping it is emphasised that the definition of doping does not provide insights into bodywork of both men and women. Moreover......, it is argued that the social and a cultural context are missing in the many epidemiological studies on the prevalence of doping. The second paper explores the difficulties of implementing an anti-doping policy, which was originally formulated in an elite sport context, in a fitness context and more...... specifically in a sport-for-all context. It is questioned whether the anti-doping policy contradicts some of the national sport-for-all organisation, DGI’s values of fostering fellowship, challenge and health. Last but not least, this thesis examines in a third paper the bodywork of the users’ of the club...

  9. Fit;o) - A M\\"ossbauer spectrum fitting program

    CERN Document Server

    Hjøllum, Jari í

    2009-01-01

    Fit;o) is a M\\"ossbauer fitting and analysis program written in Borland Delphi. It has a complete graphical user interface that allows all actions to be carried out via mouse clicks or key shortcut operations in a WYSIWYG fashion. The program does not perform complete transmission integrals, and will therefore not be suited for a complete analysis of all types of M\\"ossbauer spectra and e.g. low temperature spectra of ferrous silicates. Instead, the program is intended for application on complex spectra resulting from typical mineral samples, in which many phases and different crystallite sizes are often present at the same time. The program provides the opportunity to fit the spectra with Gaussian, Lorentzian, Split-Lorentzian, Pseudo-Voigt, Pseudo-Lorentz and Pearson-VII line profiles for individual components of the spectra. This feature is particularly useful when the sample contains components, that are affected by effects of either relaxation or interaction among particles. Fitted spectra may be printed...

  10. The Model Characteristics of Physical Fitness in CrossFit

    Directory of Open Access Journals (Sweden)

    Vasilii V. Volkov

    2014-06-01

    Full Text Available The aim of the study is to work out the model characteristics of the physical fitness of CrossFit athletes based on laboratory functional testing (n=10. The analysis of the body composition was conducted using the dual-energy absorptiometry method. The morpho-functional characteristics of the heart were explored using a high-resolution ultrasound scanner. Oxygen consumption at the aerobic-anaerobic threshold and maximum oxygen consumption were determined in a step test on arm and leg cycle ergometers using a gas-analyzer. The level of the physical fitness of leg muscles in the males and females who took part in the study was satisfactory. However, it was considerably higher than the norm for untrained people. The level of the physical fitness of arm muscles was higher than the average and matched the Master of Sport of International Class standards. The productivity of the cardio-vascular system was much higher than in healthy males and females who do not work out and comparable to the standards for advanced soccer players.

  11. Quantum algorithm for data fitting.

    Science.gov (United States)

    Wiebe, Nathan; Braun, Daniel; Lloyd, Seth

    2012-08-03

    We provide a new quantum algorithm that efficiently determines the quality of a least-squares fit over an exponentially large data set by building upon an algorithm for solving systems of linear equations efficiently [Harrow et al., Phys. Rev. Lett. 103, 150502 (2009)]. In many cases, our algorithm can also efficiently find a concise function that approximates the data to be fitted and bound the approximation error. In cases where the input data are pure quantum states, the algorithm can be used to provide an efficient parametric estimation of the quantum state and therefore can be applied as an alternative to full quantum-state tomography given a fault tolerant quantum computer.

  12. Fitness Doping and Body Management

    DEFF Research Database (Denmark)

    Thualagant, Nicole

    -based fitness centres. Based on a survey in ten Danish club-based fitness centres and on narratives from semi-structured interviews, it is highlighted that the objectives of bodywork differ according to the users’ age and gender. Two different ways of investing in the body are explored in the paper, namely...... a work on the body and a work with the body. As it is concluded, different orientations towards bodywork imply various uses of body enhancing strategies. Although the objectives of bodywork and the body investments are different, these practices seem to be based on the same quest, namely the search...

  13. Physical fitness assessment: an update.

    Science.gov (United States)

    Wilder, Robert P; Greene, Jill Amanda; Winters, Kathryne L; Long, William B; Gubler, K; Edlich, Richard F

    2006-01-01

    The American College of Sports Medicine (ACSM) gives the following definition of health-related physical fitness: Physical fitness is defined as a set of attributes that people have or achieve that relates to the ability to perform physical activity. It is also characterized by (1) an ability to perform daily activities with vigor, and (2) a demonstration of traits and capacities that are associated with a low risk of premature development of hypokinetic diseases (e.g., those associated with physical inactivity). Information from an individual's health and medical records can be combined with information from physical fitness assessment to meet the specific health goals and rehabilitative needs of that individual. Attaining adequate informed consent from participants prior to exercise testing is mandatory because of ethical and legal considerations.A physical fitness assessment includes measures of body composition, cardiorespiratory endurance, muscular fitness, and musculoskeletal flexibility. The three common techniques for assessing body composition are hydrostatic weighing, and skinfold measurements, and anthropometric measurements. Cardiorespiratory endurance is a crucial component of physical fitness assessment because of its strong correlation with health and health risks. Maximal oxygen uptake (VO2max) is the traditionally accepted criterion for measuring cardiorespiratory endurance. Although maximal-effort tests must be used to measure VO2max, submaximal exercise can be used to estimate this value. Muscular fitness has historically been used to describe an individual's integrated status of muscular strength and muscular endurance. An individual's muscular strength is specific to a particular muscle or muscle group and refers to the maximal force (N or kg) that the muscle or muscle group can generate. Dynamic strength can be assessed by measuring the movement of an individual's body against an external load. Isokinetic testing may be performed by assessing

  14. Chinese Hailed "National Fitness Program"

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    IN March, 1994, Liu Ji, Vice Minister of the State Physical Culture and Sports Commission (SPCSC) announced the "National Fitness Program" on behalf of Chinese government at the World Sports-for-All Congress in Uruguay. Almost all the participants thought it important to carry out the program in a country with a population of 1.2 billion. It not only helps improve Chinese people’s health but also the world’s average standard of health. The "National Fitness Program" is an overall, century-spanning, systematic project, which is snowballing. In 1994, the SPCSC issued the One-Two-One Project of the

  15. Decision making on fitness landscapes

    Science.gov (United States)

    Arthur, R.; Sibani, P.

    2017-04-01

    We discuss fitness landscapes and how they can be modified to account for co-evolution. We are interested in using the landscape as a way to model rational decision making in a toy economic system. We develop a model very similar to the Tangled Nature Model of Christensen et al. that we call the Tangled Decision Model. This is a natural setting for our discussion of co-evolutionary fitness landscapes. We use a Monte Carlo step to simulate decision making and investigate two different decision making procedures.

  16. Decision Making on Fitness Landscapes

    DEFF Research Database (Denmark)

    Arthur, Rudy; Sibani, Paolo

    2017-01-01

    We discuss fitness landscapes and how they can be modified to account for co-evolution. We are interested in using the landscape as a way to model rational decision making in a toy economic system. We develop a model very similar to the Tangled Nature Model of Christensen et. al. that we call...... the Tangled Decision Model. This is a natural setting for our discussion of co-evolutionary fitness landscapes. We use a Monte Carlo step to simulate decision making and investigate two different decision making procedures....

  17. Descision Making on Fitness Landscapes

    CERN Document Server

    Arthur, Rudy

    2016-01-01

    We discuss fitness landscapes and how they can be modified to account for co-evolution. We are interested in using the landscape as a way to model rational decision making in a toy economic system. We develop a model very similar to the Tangled Nature Model of Christensen et. al. that we call the Tangled Decision Model. This is a natural setting for our discussion of co-evolutionary fitness landscapes. We use a Monte Carlo step to simulate decision making and investigate two different decision making procedures.

  18. Fitness measures and health outcomes in youth

    National Research Council Canada - National Science Library

    Pate, Russell R; Oria, Maria; Pillsbury, Laura

    2012-01-01

    .... Physical fitness testing in American youth was established on a large scale in the 1950s with an early focus on performance-related fitness that gradually gave way to an emphasis on health-related fitness...

  19. A multigenerational effect of parental age on offspring size but not fitness in common duckweed (Lemna minor).

    Science.gov (United States)

    Barks, P M; Laird, R A

    2016-04-01

    Classic theories on the evolution of senescence make the simplifying assumption that all offspring are of equal quality, so that demographic senescence only manifests through declining rates of survival or fecundity. However, there is now evidence that, in addition to declining rates of survival and fecundity, many organisms are subject to age-related declines in the quality of offspring produced (i.e. parental age effects). Recent modelling approaches allow for the incorporation of parental age effects into classic demographic analyses, assuming that such effects are limited to a single generation. Does this 'single-generation' assumption hold? To find out, we conducted a laboratory study with the aquatic plant Lemna minor, a species for which parental age effects have been demonstrated previously. We compared the size and fitness of 423 laboratory-cultured plants (asexually derived ramets) representing various birth orders, and ancestral 'birth-order genealogies'. We found that offspring size and fitness both declined with increasing 'immediate' birth order (i.e. birth order with respect to the immediate parent), but only offspring size was affected by ancestral birth order. Thus, the assumption that parental age effects on offspring fitness are limited to a single generation does in fact hold for L. minor. This result will guide theorists aiming to refine and generalize modelling approaches that incorporate parental age effects into evolutionary theory on senescence.

  20. Walking Shoes: Features and Fit

    Science.gov (United States)

    ... be snug, not tight. If you're a woman with wide feet, consider men's or boys' shoes, which are cut a bit larger through the heel and the ball of the foot. Walk in the shoes before buying them. They should feel comfortable right away. Make sure your heel fits snugly in ...

  1. Self-reported cardiorespiratory fitness

    DEFF Research Database (Denmark)

    Holtermann, Andreas; Marott, Jacob Louis; Gyntelberg, Finn;

    2015-01-01

    BACKGROUND: The predictive value and improved risk classification of self-reported cardiorespiratory fitness (SRCF), when added to traditional risk factors on cardiovascular disease (CVD) and longevity, are unknown. METHODS AND RESULTS: A total of 3843 males and 5093 females from the Copenhagen...

  2. Inclusive fitness theory and eusociality

    DEFF Research Database (Denmark)

    Abbot, P.; Wrangham, R.; Abe, J.

    2011-01-01

    Arising from M. A. Nowak, C. E. Tarnita & E. O. Wilson 466, 1057-1062 (2010); Nowak et al. reply. Nowak et al. argue that inclusive fitness theory has been of little value in explaining the natural world, and that it has led to negligible progress in explaining the evolution of eusociality. Howev...

  3. Preparation of Police Fitness Instructors.

    Science.gov (United States)

    Collingwood, Thomas R.; And Others

    1979-01-01

    Concern about the declining level of physical fitness of police officers has led the Bureau of Training of the Kentucky Department of Justice and the Department of Physical Education at Eastern Kentucky University to implement a training course for police instructors. (LH)

  4. Self-Fitting Hearing Aids

    Directory of Open Access Journals (Sweden)

    Gitte Keidser

    2016-04-01

    Full Text Available A self-contained, self-fitting hearing aid (SFHA is a device that enables the user to perform both threshold measurements leading to a prescribed hearing aid setting and fine-tuning, without the need for audiological support or access to other equipment. The SFHA has been proposed as a potential solution to address unmet hearing health care in developing countries and remote locations in the developed world and is considered a means to lower cost and increase uptake of hearing aids in developed countries. This article reviews the status of the SFHA and the evidence for its feasibility and challenges and predicts where it is heading. Devices that can be considered partly or fully self-fitting without audiological support were identified in the direct-to-consumer market. None of these devices are considered self-contained as they require access to other hardware such as a proprietary interface, computer, smartphone, or tablet for manipulation. While there is evidence that self-administered fitting processes can provide valid and reliable results, their success relies on user-friendly device designs and interfaces and easy-to-interpret instructions. Until these issues have been sufficiently addressed, optional assistance with the self-fitting process and on-going use of SFHAs is recommended. Affordability and a sustainable delivery system remain additional challenges for the SFHA in developing countries. Future predictions include a growth in self-fitting products, with most future SFHAs consisting of earpieces that connect wirelessly with a smartphone and providers offering assistance through a telehealth infrastructure, and the integration of SFHAs into the traditional hearing health-care model.

  5. Industrial Psychology: Goodness of fit? Fit for goodness?

    Directory of Open Access Journals (Sweden)

    Leon J. van Vuuren

    2010-12-01

    Full Text Available Orientation: This theoretical opinion-based paper represents a critical reflection on the relevance of industrial psychology.Research purpose: Against a historical-developmental background of the discipline, the inquiry questions its goodness of fit, that is its contribution to organisation and society.Motivation for the study: Regular introspection in the discipline ensures that it remains relevant in both science and practice. As such, such introspection calls for a meta-theoretical imperative, to ensure that industrial psychology is fully aware of how the theoretical models applied in the discipline influence people and the society that they form part of.Research design, approach and method: The question of industrial psychology’s potential fit for goodness that is broader than what is merely good for the organisation and its employees is explored with a view to enhancing its relevance. The exploration is conducted through the utilisation of theoretical argumentation in which industrial psychology is analysed in terms of contextual considerations that require the discipline to evaluate its real versus its potential contribution to society.Main findings: It is found that the fit is limited to its relevance for inwardly focused organisational behaviour due to its endorsement of the instrumental (strategic motives of organisations that subscribe to an owner and/or shareholder agenda.Practical/managerial implications: In light of the main finding, industrial psychology’s potential fit for goodness is explored with a view to enhancing its relevance in an era of goodness. The creation of a scientific and practical interface between industrial psychology and business ethics is suggested to facilitate movement away from a descriptive approach.Contribution/value-add: The heuristics of reflection, reform, research and resources are suggested to facilitate movement towards a normative (multiple stakeholder paradigm aimed at broad based goodness and

  6. Industrial Psychology: Goodness of fit? Fit for goodness?

    OpenAIRE

    Leon J. van Vuuren

    2010-01-01

    Orientation: This theoretical opinion-based paper represents a critical reflection on the relevance of industrial psychology.Research purpose: Against a historical-developmental background of the discipline, the inquiry questions its goodness of fit, that is its contribution to organisation and society.Motivation for the study: Regular introspection in the discipline ensures that it remains relevant in both science and practice. As such, such introspection calls for a meta-theoretical imperat...

  7. Benefit segmentation of the fitness market.

    Science.gov (United States)

    Brown, J D

    1992-01-01

    While considerate attention is being paid to the fitness and wellness needs of people by healthcare and related marketing organizations, little research attention has been directed to identifying the market segments for fitness based upon consumers' perceived benefits of fitness. This article describes three distinct segments of fitness consumers comprising an estimated 50 percent of households. Implications for marketing strategies are also presented.

  8. Youth Physical Fitness: Ten Key Concepts

    Science.gov (United States)

    Corbin, Charles B.; Welk, Gregory J.; Richardson, Cheryl; Vowell, Catherine; Lambdin, Dolly; Wikgren, Scott

    2014-01-01

    The promotion of physical fitness has been a key objective of physical education for more than a century. During this period, physical education has evolved to accommodate changing views on fitness and health. The purpose of this article is to discuss issues with fitness assessment and fitness education central to the new Presidential Youth…

  9. Youth Physical Fitness: Ten Key Concepts

    Science.gov (United States)

    Corbin, Charles B.; Welk, Gregory J.; Richardson, Cheryl; Vowell, Catherine; Lambdin, Dolly; Wikgren, Scott

    2014-01-01

    The promotion of physical fitness has been a key objective of physical education for more than a century. During this period, physical education has evolved to accommodate changing views on fitness and health. The purpose of this article is to discuss issues with fitness assessment and fitness education central to the new Presidential Youth…

  10. Seeing How Fitting Process Works

    CERN Document Server

    Montalbano, Vera

    2016-01-01

    A common problem in teaching Physics in secondary school is due to the gap in terms of difficulty between the physical concepts and the mathematical tools which are necessary to study them quantitatively. Advanced statistical estimators are commonly introduced only a couple of years later than some common physical topics, such as e.g. the electronic circuit analysis. Filling this gap with alternative methods appears to be opportune, in order to let the students reach a full comprehension of the issue they are facing with. In this work we use a smartphone camera and GeoGebra to propose a visual method for understanding the physical meaning of a fitting process. The time constant of an RC circuit is estimated by fitting the discharge curve of a capacitor visualized on the screen of an oscilloscope.

  11. The Andersen aerobic fitness test

    DEFF Research Database (Denmark)

    Aadland, Eivind; Terum, Torkil; Mamen, Asgeir

    2014-01-01

    of agreement) were 26.7±125.2 m for test 2 vs. test 1 (ptest 3 vs. test 2 (p = .514 for mean difference). The equation to estimate VO2peak suggested by Andersen et al. (2008) showed a poor fit in the present sample; thus, we suggest a new equation: VO2peak = 23......BACKGROUND: High aerobic fitness is consistently associated with a favorable metabolic risk profile in children. Direct measurement of peak oxygen consumption (VO2peak) is often not feasible, thus indirect tests such as the Andersen test are required in many settings. The present study seeks...... to determine the reliability and validity of the Andersen test in 10-year-old children. METHODS: A total of 118 10-year-old children (67 boys and 51 girls) were recruited from one school and performed four VO2peak tests over three weeks: three Andersen tests (indirect) and one continuous progressive treadmill...

  12. Hearing Aid Fitting & Electrophysiologic Procedure

    Directory of Open Access Journals (Sweden)

    Bahram Jalaei

    2001-05-01

    Full Text Available Rehabilitation of deaf individual is one of the important subjects that has attracted attention of many researchers during past centuries. Different opinions have been established in this direction. Electrophysiologic tests were established and developed parallel to developments in rehabilitation. Therefore, opinion of using electrophysiologic test for evaluation and fitting of hearing aid became gradually popular. Ultimately, the electrophysiologic tests are used in evaluation and fitting of hearing aid in two ways: 1-Direct way 2- Indirect way "nIn direct way aided ABR is obtained and special attention is paid to wave V. This technique has many difficulties. Inindirect way, electrophysiologic tests such, ECochG, OAE and ABR, AMLR, ALR and P300 and other objective tests are used, especially in infants and neonates for evaluating the state of hearing. Researches are continuing in this field. It is probable to have aided electrophysiologic responses with speech stimuli in near future.

  13. [Aerobic fitness in police officers].

    Science.gov (United States)

    Capodaglio, E M; Imbriani, M; Criffò, A; Tronconi, E

    1996-01-01

    According to act n. 626, individual assessment of fitness and absence of contraindications for carrying on a job is fundamental. We considered a group of 44 Urban Police officers (36 males, 8 females), age 39.7 +/- 9.1, whose principal job requirement is a good energetic and motor availability, for a fitness evaluation through a submaximal treadmill test, with subsequent steps of 6 minutes. During the test, physiological variables (VO2, VE, QR through a metabograph, Hr trough an Ec-monitor and Pa through a manual sphygmomanometer) and subjective evaluations of fatigue and dyspnea were monitored. Studying the individual variables trend it was possible to identify the critical metabolic level that was easily tolerated by each individual. This level, an average of 6.8 MET corresponding to a heavy activity, is an endurance predictor and can be utilized in subsequent controls.

  14. Leading a Culture of Fitness

    Science.gov (United States)

    2011-03-24

    Program. As shown earlier, VO2max is a good indicator of cardio respiratory fitness. A maximum effort test on a treadmill is one of the most...accepted and accurate methods to determine VO2max , but the test is lengthy, complicated, and comes with risks. To avoid these drawbacks, the Air Force 9...adopted a sub-maximal cycle ergometry test (SCET) designed to estimate VO2max . These tests were accurate within the range of ten to twenty percent

  15. Fit to Electroweak Precision Data

    CERN Document Server

    Erler, J

    2006-01-01

    A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively light Higgs boson. I will also give an outlook on future developments at the Tevatron Run II, CEBAF, the LHC, and the ILC.

  16. Physical Work Demands and Fitness

    DEFF Research Database (Denmark)

    Larsen, Mette Korshøj

    resting and sleeping heart rate, relative aerobic workload and level of high sensitive C-reactive protein. However, the intervention also elevated resting and 24-hour ambulatory blood pressure. Secondary analysis, stratified on high vs low (≥/... exposed to high relative aerobic workloads obtained more pronounced increases of resting and 24-hour ambulatory blood pressure, an unaltered cardiorespiratory fitness and a reduced sleeping heart rate. The enhanced resting and 24-hour ambulatory blood pressure may be explained as a potential...

  17. Profound effects of population density on fitness-related traits in an invasive freshwater snail.

    Directory of Open Access Journals (Sweden)

    Nicholas Zachar

    Full Text Available Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum, a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum. These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology.

  18. The expansion of Ulva prolifera O.F. Müller macroalgal blooms in the Yellow Sea, PR China, through asexual reproduction.

    Science.gov (United States)

    Zhang, Jianheng; Kim, Jang Kyun; Yarish, Charles; He, Peimin

    2016-03-15

    Since 2007, Ulva macroalgal blooms have occurred along the coastal areas of the Yellow Sea, China. These blooms are dominated by fragments of Ulva prolifera in the early stages of development. The objectives of this study were to identify the primary mode of asexual reproduction for U. prolifera and to evaluate the contribution of these thalli fragments to the formation of blooms. Four different growth and reproductive strategies of U. prolifera segments were found including: 1) tubular diameter becoming larger; 2) formation of new branches; 3) release of zoids; and 4) polarized growth. This is the first report showing the development of numerous blade-lets from a single segment, which is remarkably different from previous studies on other Ulva species. The results in the present study provide critical information to understand how this species is able to support its explosive growth during a bloom.

  19. 西藏野生薄荷的无性繁殖研究%Research on asexual reproduction of Tibetan wild mint

    Institute of Scientific and Technical Information of China (English)

    米玛潘多; 泽仁旺姆; 尼珍; 郭尚磊; 达娃旺姆

    2011-01-01

    In this Paper, asexual reproduction of Tibetan wild mint was researched and, the effect of different concentrations of hormones and ratio of different hormones on induction of differentiation and rooting were analyzed as well. The results showed that the%文章对西藏野生薄荷进行了无性繁殖研究,分析了不同浓度的激素和不同激素配比对野生薄荷分化诱导和生根诱导影响,并认为最佳分化培养基为:MS+6BA0.5+IAA0.5mg/L+pH5.8;最佳生根培养基为:MS+NAAlmg/L+pH5.8。

  20. MoVrp1, a putative verprolin protein, is required for asexual development and infection in the rice blast fungus Magnaporthe oryzae

    Science.gov (United States)

    Huang, Lin; Zhang, Shengpei; Yin, Ziyi; Liu, Muxing; Li, Bing; Zhang, Haifeng; Zheng, Xiaobo; Wang, Ping; Zhang, Zhengguang

    2017-01-01

    Endocytosis is a crucial cellular process in eukaryotic cells which involves clathrin and/or adaptor proteins, lipid kinases, phosphatases and the actin cytoskeleton. Verprolin proteins, such as Vrp1 in Saccharomyces cerevisiae, are conserved family proteins that regulate actin binding and endocytosis. Here, we identified and characterized MoVrp1 as the yeast Vrp1 homolog in Magnaporthe oryzae. Deletion of the MoVRP1 gene resulted in defects in vegetative growth, asexual development, and infection of the host plant. The ∆Movrp1 mutants also exhibited decreased extracellular peroxidase and laccase activities and showed defects in colony pigmentation, hyphal surface hydrophobicity, cell wall integrity, autophagy, endocytosis, and secretion of avirulent effector. Our studies provided new evidences that MoVrp1 involved in actin cytoskeleton is important for growth, morphogenesis, cellular trafficking, and fungal pathogenesis. PMID:28117435

  1. The first multi-gene phylogeny of the Macrostomorpha sheds light on the evolution of sexual and asexual reproduction in basal Platyhelminthes.

    Science.gov (United States)

    Janssen, Toon; Vizoso, Dita B; Schulte, Gregor; Littlewood, D Timothy J; Waeschenbach, Andrea; Schärer, Lukas

    2015-11-01

    The Macrostomorpha-an early branching and species-rich clade of free-living flatworms-is attracting interest because it contains Macrostomum lignano, a versatile model organism increasingly used in evolutionary, developmental, and molecular biology. We elucidate the macrostomorphan molecular phylogeny inferred from both nuclear (18S and 28S rDNA) and mitochondrial (16S rDNA and COI) marker genes from 40 representatives. Although our phylogeny does not recover the Macrostomorpha as a statistically supported monophyletic grouping, it (i) confirms many taxa previously proposed based on morphological evidence, (ii) permits the first placement of many families and genera, and (iii) reveals a number of unexpected placements. Specifically, Myozona and Bradynectes are outside the three classic families (Macrostomidae, Microstomidae and Dolichomacrostomidae) and the asexually fissioning Myomacrostomum belongs to a new subfamily, the Myozonariinae nov. subfam. (Dolichomacrostomidae), rather than diverging early. While this represents the first evidence for asexuality among the Dolichomacrostomidae, we show that fissioning also occurs in another Myozonariinae, Myozonaria fissipara nov. sp. Together with the placement of the (also fissioning) Microstomidae, namely as the sister taxon of Dolichomacrostomidae, this suggests that fissioning is not basal within the Macrostomorpha, but rather restricted to the new taxon Dolichomicrostomida (Dolichomacrostomidae+Microstomidae). Furthermore, our phylogeny allows new insights into the evolution of the reproductive system, as ancestral state reconstructions reveal convergent evolution of gonads, and male and female genitalia. Finally, the convergent evolution of sperm storage organs in the female genitalia appears to be linked to the widespread occurrence of hypodermic insemination among the Macrostomorpha. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. A Brazilian population of the asexual fungus-growing ant Mycocepurus smithii (Formicidae, Myrmicinae, Attini) cultivates fungal symbionts with gongylidia-like structures.

    Science.gov (United States)

    Masiulionis, Virginia E; Rabeling, Christian; De Fine Licht, Henrik H; Schultz, Ted; Bacci, Maurício; Bezerra, Cintia M Santos; Pagnocca, Fernando C

    2014-01-01

    Attine ants cultivate fungi as their most important food source and in turn the fungus is nourished, protected against harmful microorganisms, and dispersed by the ants. This symbiosis evolved approximately 50-60 million years ago in the late Paleocene or early Eocene, and since its origin attine ants have acquired a variety of fungal mutualists in the Leucocoprineae and the distantly related Pterulaceae. The most specialized symbiotic interaction is referred to as "higher agriculture" and includes leafcutter ant agriculture in which the ants cultivate the single species Leucoagaricus gongylophorus. Higher agriculture fungal cultivars are characterized by specialized hyphal tip swellings, so-called gongylidia, which are considered a unique, derived morphological adaptation of higher attine fungi thought to be absent in lower attine fungi. Rare reports of gongylidia-like structures in fungus gardens of lower attines exist, but it was never tested whether these represent rare switches of lower attines to L. gonglyphorus cultivars or whether lower attine cultivars occasionally produce gongylidia. Here we describe the occurrence of gongylidia-like structures in fungus gardens of the asexual lower attine ant Mycocepurus smithii. To test whether M. smithii cultivates leafcutter ant fungi or whether lower attine cultivars produce gongylidia, we identified the M. smithii fungus utilizing molecular and morphological methods. Results shows that the gongylidia-like structures of M. smithii gardens are morphologically similar to gongylidia of higher attine fungus gardens and can only be distinguished by their slightly smaller size. A molecular phylogenetic analysis of the fungal ITS sequence indicates that the gongylidia-bearing M. smithii cultivar belongs to the so-called "Clade 1"of lower Attini cultivars. Given that M. smithii is capable of cultivating a morphologically and genetically diverse array of fungal symbionts, we discuss whether asexuality of the ant host maybe

  3. Where does fitness fit in theories of perception?

    Science.gov (United States)

    Anderson, Barton L

    2015-12-01

    Interface theory asserts that neither our perceptual experience of the world nor the scientific constructs used to describe the world are veridical. The primary argument used to uphold this claim is that (1) evolution is driven by a process of natural selection that favors fitness over veridicality, and (2) payoffs do not vary monotonically with truth. I argue that both the arguments used to bolster this claim and the conclusions derived from it are flawed. Interface theory assumes that perception evolved to directly track fitness but fails to consider the role of adaptation on ontogenetic time scales. I argue that the ubiquity of nonmonotonic payoff functions requires that (1) perception tracks "truth" for species that adapt on ontogenetic time scales and (2) that perception should be distinct from utility. These conditions are required to pursue an adaptive strategy to mitigate homeostatic imbalances. I also discuss issues with the interface metaphor, the particular formulation of veridicality that is considered, and the relationship of interface theory to the history of ideas on these topics.

  4. A causal dispositional account of fitness.

    Science.gov (United States)

    Triviño, Vanessa; Nuño de la Rosa, Laura

    2016-09-01

    The notion of fitness is usually equated to reproductive success. However, this actualist approach presents some difficulties, mainly the explanatory circularity problem, which have lead philosophers of biology to offer alternative definitions in which fitness and reproductive success are distinguished. In this paper, we argue  that none of these alternatives is satisfactory and, inspired by Mumford and Anjum's dispositional theory of causation, we offer a definition of fitness as a causal dispositional property. We argue that, under this framework, the distinctiveness that biologists usually attribute to fitness-namely, the fact that fitness is something different from both the physical traits of an organism and the number of offspring it leaves-can be explained, and the main problems associated with the concept of fitness can be solved. Firstly, we introduce Mumford and Anjum's dispositional theory of causation and present our definition of fitness as a causal disposition. We explain in detail each of the elements involved in our definition, namely: the relationship between fitness and the functional dispositions that compose it, the emergent character of fitness, and the context-sensitivity of fitness. Finally, we explain how fitness and realized fitness, as well as expected and realized fitness are distinguished in our approach to fitness as a causal disposition.

  5. The iFit: an integrated physical fitness testing system to evaluate the degree of physical fitness of the elderly.

    Science.gov (United States)

    Tseng, Kevin C; Wong, Alice May-Kuen; Hsu, Chien-Lung; Tsai, Tsai-Hsuan; Han, Chang-Mu; Lee, Ming-Ren

    2013-01-01

    This paper presents an integrated physical fitness testing system (iFit) that evaluates the physical fitness of older adults. The intent of the test is to help them manage and promote their health and mitigate the effects of aging. National protocols of physical fitness were implemented to support the assessment. The proposed system encompasses four modules of physical fitness assessment for both users and medical professionals. The test information will be recorded and managed through a wireless sensor network that will enable a better understanding of users' fitness states. Furthermore, the iFit has been validated by a test session attended by elderly participants. The results show that there is a significant correlation between iFit use in the test of flexibility, grip strength, and balance, compared to conventional methods.

  6. Social personality trait and fitness.

    Science.gov (United States)

    Cote, J; Dreiss, A; Clobert, J

    2008-12-22

    Several recent studies have explored various aspects of animal personality and their ecological consequences. However, the processes responsible for the maintenance of personality variability within a population are still largely unknown. We have recently demonstrated that social personality traits exist in the common lizard (Lacerta vivipara) and that the variation in sociability provides an explanation for variable dispersal responses within a given species. However, we need to know the fitness consequences of variation in sociability across environmental contexts in order to better understand the maintenance of such variation. In order to achieve this, we investigated the relationship between sociability and survival, body growth and fecundity, in one-year-old individuals in semi-natural populations with varying density. 'Asocial' and 'social' lizards displayed different fitness outcomes in populations of different densities. Asocial lizards survived better in low-density populations, while social females reproduced better. Spatiotemporal variation in environmental conditions might thus be the process underlying the maintenance of these personality traits within a population. Finally, we also discuss the position of sociability in a more general individual behavioural pattern including boldness, exploration and aggressiveness.

  7. Alternative Forms of Fit in Contingency Theory.

    Science.gov (United States)

    Drazin, Robert; Van de Ven, Andrew H.

    1985-01-01

    This paper examines the selection, interaction, and systems approaches to fit in structural contingency theory. The concepts of fit evaluated may be applied not only to structural contingency theory but to contingency theories in general. (MD)

  8. President's Council on Fitness, Sports and Nutrition

    Science.gov (United States)

    ... A Print Share President's Council on Fitness, Sports & Nutrition (PCFSN) Fitness Homepage Intro Tile PCFSN engages, educates, ... lifestyle that includes regular physical activity and good nutrition. Since 1956, the Council has created and promoted ...

  9. Tile-Compressed FITS Kernel for IRAF

    Science.gov (United States)

    Seaman, R.

    2011-07-01

    The Flexible Image Transport System (FITS) is a ubiquitously supported standard of the astronomical community. Similarly, the Image Reduction and Analysis Facility (IRAF), developed by the National Optical Astronomy Observatory, is a widely used astronomical data reduction package. IRAF supplies compatibility with FITS format data through numerous tools and interfaces. The most integrated of these is IRAF's FITS image kernel that provides access to FITS from any IRAF task that uses the basic IMIO interface. The original FITS kernel is a complex interface of purpose-built procedures that presents growing maintenance issues and lacks recent FITS innovations. A new FITS kernel is being developed at NOAO that is layered on the CFITSIO library from the NASA Goddard Space Flight Center. The simplified interface will minimize maintenance headaches as well as add important new features such as support for the FITS tile-compressed (fpack) format.

  10. Sun Jinfang Establishes A Fitness Network

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    HIRING a fitness consultant for one year is as easy as filling in a form and paying 10 yuan to get a membership. You will receive a bulletin entitled Fitness Guide and therefore after the bulletin provides free health

  11. Betoonviimistlus on kaunis, aga kulukas / Monica Raud

    Index Scriptorium Estoniae

    Raud, Monica, 1981-

    2005-01-01

    Betooni kasutamisest siseviimistluses. Kakumäel asuvast eramust, mis koosneb valdavas osas klaasist ja betoonist, kommenteerivad sisekujundaja Raina Lillepõld, arhitekt Indrek Tiigi, arhitekt Emil Urbel

  12. Edasi loodusesse! Aga kuhu? / Riina Oruaas

    Index Scriptorium Estoniae

    Oruaas, Riina

    2007-01-01

    Tantsulavastustest: Oksana Titova, Päär Pärenson ja Juhan Ulfsak "Roots", Kaja Kanni sooloetendus "There are Laika dogs living in Estonia", Tiina Mölder, Kaja Kann ja Bush Hartshor "Naine ja Hunt"

  13. Hiilgav, aga... / Alar Niineväli

    Index Scriptorium Estoniae

    Niineväli, Alar

    2008-01-01

    Ameerika telesarjad, mis on heatasemelised, kuid tootjate poolt liiga vara ära lõpetatud, enamasti kasumlikkusest lähtudes : "Earth 2" (1994), "EZ Streets" (1996), "Profit" (1996), "Strange World" (1999), "The Inside" (2005), "Drive" (2007), "Aliens in America" (2007)

  14. Edasi loodusesse! Aga kuhu? / Riina Oruaas

    Index Scriptorium Estoniae

    Oruaas, Riina

    2007-01-01

    Tantsulavastustest: Oksana Titova, Päär Pärenson ja Juhan Ulfsak "Roots", Kaja Kanni sooloetendus "There are Laika dogs living in Estonia", Tiina Mölder, Kaja Kann ja Bush Hartshor "Naine ja Hunt"

  15. Hiilgav, aga... / Alar Niineväli

    Index Scriptorium Estoniae

    Niineväli, Alar

    2008-01-01

    Ameerika telesarjad, mis on heatasemelised, kuid tootjate poolt liiga vara ära lõpetatud, enamasti kasumlikkusest lähtudes : "Earth 2" (1994), "EZ Streets" (1996), "Profit" (1996), "Strange World" (1999), "The Inside" (2005), "Drive" (2007), "Aliens in America" (2007)

  16. A Fitness Center for Senior Citizens

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    APHYSICALfitnesscenterforseniorcitizenshasrecentlybeenopenedinBeijing’sYuetanGym."Ourcenterisaschool,akeyandabank,"saysLiuXuecheng,manageroftheBeijingYinxuanFitnessCenterfortheElderly."Itisaschoolbecauseourcenterteachestheelderlyabouthealth;itisakeyb...

  17. HRM and Fit: Survival of the fittest!?

    NARCIS (Netherlands)

    C.T. Boon (Corine)

    2008-01-01

    textabstractWhat is the nature of ‘fit’ in strategic HRM? This is the question guiding this thesis. Although the idea of fit is theoretically convincing, empirical evidence to support the role of fit is limited. Previous studies on fit have mainly focused on the alignment between HRM and strategy

  18. 48 CFR 752.7033 - Physical fitness.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Physical fitness. 752.7033... FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Texts of USAID Contract Clauses 752.7033 Physical fitness. For use in all USAID contracts involving performance overseas. Physical Fitness (JUL 1997)...

  19. Having a Ball with Fitness Balls

    Science.gov (United States)

    McNulty, Betty

    2011-01-01

    Fitness programs can be greatly enhanced with the addition of fitness balls. They are a fun, challenging, economical, and safe way to incorporate a cardiovascular, strength, and stretching program for all fitness levels in a physical education setting. The use of these balls has become more popular during the last decade, and their benefits and…

  20. Fit - The Key to Organizational Design

    Directory of Open Access Journals (Sweden)

    Lex Donaldson

    2014-12-01

    Full Text Available The design of an organization needs to fit its situation. Designs that fit produce higher organizational performance than designs that do not.  This article uses the concept of fit to show how to align organizational designs to three important situational factors: competitive strategy, organization size, and task uncertainty.

  1. HRM and Fit: Survival of the fittest!?

    NARCIS (Netherlands)

    C.T. Boon (Corine)

    2008-01-01

    textabstractWhat is the nature of ‘fit’ in strategic HRM? This is the question guiding this thesis. Although the idea of fit is theoretically convincing, empirical evidence to support the role of fit is limited. Previous studies on fit have mainly focused on the alignment between HRM and strategy (s

  2. In a Peak Fitness Condition?

    DEFF Research Database (Denmark)

    Storm, Rasmus K.; Nielsen, Klaus

    2010-01-01

    managerial efforts with regard to Danish elite sports? The analysis finds the Danish elite sports organization, Team Danmark, well prepared and fit for the future challenges. Still, though, areas such as talent identification and development and division of roles and responsibilities, are in need...... increased, the market has adapted by raising the overall price of a medal. As a direct consequence managerial efficiency can be a 'non-financial' tool for nations to enhance the chances of success. The purpose of this article is to describe the internationalisation of elite sports together with analysing...... of improvement in order to strengthen the managerial efficiency. Furthermore the question of more funding is discussed.  Recently the Danish medal standings have been deteriorating which has initiated requests for more funding and the political response could be increased public funds....

  3. Physical Work Demands and Fitness

    DEFF Research Database (Denmark)

    Larsen, Mette Korshøj

    Cardiovascular disease is the most frequent cause of death, accounting for more than 30 % of all annual deaths. Elevated incidence of cardiovascular disease is seen among occupational groups exposed to high occupational physical activity, like cleaners. Conversely, moderate to high leisure time...... physical activity reduces risk factors for cardiovascular disease. However, it is not known whether this also holds for workers exposed to high occupational physical activity, or whether it will lead to a cardiovascular overload. The study therefore investigated whether an aerobic exercise worksite....... The effects were evaluated with objective physiological or diurnal data in an intention-to-treat analysis using multi-adjusted mixed models. The results indicated that the intervention led to several improvements in risk factors for cardiovascular disease, e.g. enhanced cardiorespiratory fitness, reduced...

  4. AMS-02 fits Dark Matter

    CERN Document Server

    Balázs, Csaba

    2015-01-01

    In this work we perform a comprehensive statistical analysis of the AMS-02 electron, positron fluxes and the antiproton-to-proton ratio in the context of a simplified dark matter model. We include known, standard astrophysical sources and a dark matter component in the cosmic ray injection spectra. To predict the AMS-02 observables we use propagation parameters extracted from observed fluxes of heavier nuclei and the low energy part of the AMS-02 data. We assume that the dark matter particle is a Majorana fermion coupling to third generation fermions via a spin-0 mediator, and annihilating to multiple channels at once. The simultaneous presence of various annihilation channels provides the dark matter model with additional flexibility, and this enables us to simultaneously fit all cosmic ray spectra using a simple particle physics model and coherent astrophysical assumptions. Our results indicate that AMS-02 observations are not only consistent with the dark matter hypothesis within the uncertainties, but add...

  5. The Goodness of Simultaneous Fits in ISIS

    CERN Document Server

    Kühnel, Matthias; Grossberger, Christoph; Ballhausen, Ralf; Dauser, Thomas; Schwarm, Fritz-Walter; Kreykenbohm, Ingo; Nowak, Michael A; Pottschmidt, Katja; Ferrigno, Carlo; Rothschild, Richard E; Martínez-Núñez, Silvia; Torrejón, José Miguel; Fürst, Felix; Klochkov, Dmitry; Staubert, Rüdiger; Kretschmar, Peter; Wilms, Jörn

    2016-01-01

    In a previous work, we introduced a tool for analyzing multiple datasets simultaneously, which has been implemented into ISIS. This tool was used to fit many spectra of X-ray binaries. However, the large number of degrees of freedom and individual datasets raise an issue about a good measure for a simultaneous fit quality. We present three ways to check the goodness of these fits: we investigate the goodness of each fit in all datasets, we define a combined goodness exploiting the logical structure of a simultaneous fit, and we stack the fit residuals of all datasets to detect weak features. These tools are applied to all RXTE-spectra from GRO 1008-57, revealing calibration features that are not detected significantly in any single spectrum. Stacking the residuals from the best-fit model for the Vela X-1 and XTE J1859+083 data evidences fluorescent emission lines that would have gone undetected otherwise.

  6. THE GOODNESS OF SIMULTANEOUS FITS IN ISIS

    Directory of Open Access Journals (Sweden)

    Matthias Kühnel

    2016-02-01

    Full Text Available In a previous work, we introduced a tool for analyzing multiple datasets simultaneously, which has been implemented into ISIS. This tool was used to fit many spectra of X-ray binaries. However, the large number of degrees of freedom and individual datasets raise an issue about a good measure for a simultaneous fit quality. We present three ways to check the goodness of these fits: we investigate the goodness of each fit in all datasets, we define a combined goodness exploiting the logical structure of a simultaneous fit, and we stack the fit residuals of all datasets to detect weak features. These tools are applied to all RXTE-spectra from GRO 1008−57, revealing calibration features that are not detected significantly in any single spectrum. Stacking the residuals from the best-fit model for the Vela X-1 and XTE J1859+083 data evidences fluorescent emission lines that would have gone undetected otherwise.

  7. Properties of Rasch residual fit statistics.

    Science.gov (United States)

    Wu, Margaret; Adams, Richard J

    2013-01-01

    This paper examines the residual-based fit statistics commonly used in Rasch measurement. In particular, the paper analytically examines some of the theoretical properties of the residual-based fit statistics with a view to establishing the inferences that can be made using these fit statistics. More specifically, the relationships between the distributional properties of the fit statistics and sample size are discussed; some research that erroneously concludes that residual-based fit statistics are unstable is reviewed; and finally, it is analytically illustrated that, for dichotomous items, residual-based fit statistics provide a measure of the relative slope of empirical item characteristic curves. With a clear understanding of the theoretical properties of the fit statistics, the use and limitations of these statistics can be placed in the right light.

  8. Viral fitness: definitions, measurement, and current insights

    Science.gov (United States)

    Wargo, Andrew R.; Kurath, Gael

    2012-01-01

    Viral fitness is an active area of research, with recent work involving an expanded number of human, non-human vertebrate, invertebrate, plant, and bacterial viruses. Many publications deal with RNA viruses associated with major disease emergence events, such as HIV-1, influenza virus, and Dengue virus. Study topics include drug resistance, immune escape, viral emergence, host jumps, mutation effects, quasispecies diversity, and mathematical models of viral fitness. Important recent trends include increasing use of in vivo systems to assess vertebrate virus fitness, and a broadening of research beyond replicative fitness to also investigate transmission fitness and epidemiologic fitness. This is essential for a more integrated understanding of overall viral fitness, with implications for disease management in the future.

  9. Los mitos de origen en la génesis de las identidades nacionales. La batalla de Arrigorríaga y el surgimiento del particularismo vasco (ss. XIV-XVI

    Directory of Open Access Journals (Sweden)

    Jon JUARISTI

    2010-02-01

    Full Text Available RESUMEN: Autores como Poliakov, Anthony D. Smith o Paul Veyne han escrito páginas muy interesantes sobre los mitos o relatos de origen y el papel que éstos han jugado en el surgimiento de las identidades étnicas y nacionales. En línea con estos trabajos, en el presente ensayo se analiza el mito vasco y la cronología de la formación de los rasgos definitorios de la etnia vasca. El análisis de los relatos de García de Salazar y del Nobiliario del conde don Pedro Alfonso permiten extraer interesantes conclusiones sobre las leyendas de don Zuría, los orígenes de la Casa de Haro y la etnia vasca. Las transformaciones en la sociedad hidalga vizcaína del siglo XVI que motivaron cambios en el enunciado del mito de la batalla de Arrigorríaga, las causas que explican la leyenda del licenciado Andrés de Poza o la reescritura que de ese mismo mito de origen llevará a cabo mucho después el fundador del nacionalismo vasco son otros tantos temas tratados en este artículo. ABSTRACT: Authors such as Poliakov, Anthony D. Smith or Paul Veyne have written some very interesting pages on myths or stories of origins and the roles these have played in the forming of ethnic or national identities. In line with this work, the present essay analyzes the Basque myth and the chronology of the formation of the distinctive traits of the Basque ethnic group. Analysis of the stories of García de Salazar and of the genealogical work of Conde Don Pedro Alfonso allows us to draw interesting conclusions about the legends of Don Zuría, the origins of the House of Haro and the Basque ethnic group. The transformations in the noble society of Biscay in the 16th century that motivated changes in the telling of the myth of the Battle of Arrigoriaga, the causes explaining the legend of the gradúate Andrés de Poza or the rewriting of the same myth of origin that the founder of Basque nationalism would undertake much later are some of the other topics dealt with in this

  10. Parameterization for fitting triangular mesh

    Institute of Scientific and Technical Information of China (English)

    LIN Hongwei; WANG Guojin; LIU Ligang; BAO Hujun

    2006-01-01

    In recent years, with the development of 3D data acquisition equipments, the study on reverse engineering has become more and more important. However, the existing methods for parameterization can hardly ensure that the parametric domain is rectangular, and the parametric curve grid is regular. In order to overcome these limitations, we present a novel method for parameterization of triangular meshes in this paper. The basic idea is twofold: first, because the isotherms in the steady temperature do not intersect with each other, and are distributed uniformly, no singularity (fold-over) exists in the parameterization; second, a 3D harmonic equation is solved by the finite element method to obtain the steady temperature field on a 2D triangular mesh surface with four boundaries. Therefore, our proposed method avoids the embarrassment that it is impossible to solve the 2D quasi-harmonic equation on the 2D triangular mesh without the parametric values at mesh vertices. Furthermore, the isotherms on the temperature field are taken as a set of iso-parametric curves on the triangular mesh surface. The other set of iso-parametric curves can be obtained by connecting the points with the same chord-length on the isotherms sequentially. The obtained parametric curve grid is regular, and distributed uniformly, and can map the triangular mesh surface to the unit square domain with boundaries of mesh surface to boundaries of parametric domain, which ensures that the triangular mesh surface or point cloud can be fitted with the NURBS surface.

  11. Hierarchy, leadership, and construal fit.

    Science.gov (United States)

    Berson, Yair; Halevy, Nir

    2014-09-01

    Three studies tested the hypothesis, derived from construal-level theory, that hierarchical distance between leaders and followers moderates the effectiveness of leader behaviors such that abstract behaviors produce more positive outcomes when enacted across large hierarchical distances, whereas concrete behaviors produce more positive outcomes when enacted across small hierarchical distances. In Study 1 (N = 2,206 employees of a telecommunication organization), job satisfaction was higher when direct supervisors provided employees with concrete feedback and hierarchically distant leaders shared with them their abstract vision rather than vice versa. Study 2 orthogonally crossed hierarchical distances with communication type, operationalized as articulating abstract values versus sharing a detailed story exemplifying the same values; construal misfit mediated the interactive effects of hierarchical distance and communication type on organizational commitment and social bonding. Study 3 similarly manipulated hierarchical distances and communication type, operationalized as concrete versus abstract calls for action in the context of a severe professional crisis. Group commitment and participation in collective action were higher when a hierarchically proximate leader communicated a concrete call for action and a hierarchically distant leader communicated an abstract call for action rather than vice versa. These findings highlight construal fit's positive consequences for individuals and organizations.

  12. Nonlinear fitness landscape of a molecular pathway.

    Directory of Open Access Journals (Sweden)

    Lilia Perfeito

    2011-07-01

    Full Text Available Genes are regulated because their expression involves a fitness cost to the organism. The production of proteins by transcription and translation is a well-known cost factor, but the enzymatic activity of the proteins produced can also reduce fitness, depending on the internal state and the environment of the cell. Here, we map the fitness costs of a key metabolic network, the lactose utilization pathway in Escherichia coli. We measure the growth of several regulatory lac operon mutants in different environments inducing expression of the lac genes. We find a strikingly nonlinear fitness landscape, which depends on the production rate and on the activity rate of the lac proteins. A simple fitness model of the lac pathway, based on elementary biophysical processes, predicts the growth rate of all observed strains. The nonlinearity of fitness is explained by a feedback loop: production and activity of the lac proteins reduce growth, but growth also affects the density of these molecules. This nonlinearity has important consequences for molecular function and evolution. It generates a cliff in the fitness landscape, beyond which populations cannot maintain growth. In viable populations, there is an expression barrier of the lac genes, which cannot be exceeded in any stationary growth process. Furthermore, the nonlinearity determines how the fitness of operon mutants depends on the inducer environment. We argue that fitness nonlinearities, expression barriers, and gene-environment interactions are generic features of fitness landscapes for metabolic pathways, and we discuss their implications for the evolution of regulation.

  13. Generation of an antibody that recognizes Plasmodium chabaudi cysteine protease (chabaupain-1) in both sexual and asexual parasite life cycle and evaluation of chabaupain-1 vaccine potential.

    Science.gov (United States)

    Armada, Ana; Gazarini, Marcos L; Gonçalves, Lídia M; Antunes, Sandra; Custódio, Ana; Rodrigues, Armanda; Almeida, António J; Silveira, Henrique; Rosário, Virgílio do; Santos-Gomes, Gabriela; Domingos, Ana

    2013-09-01

    Malaria cysteine proteases have been shown to be immunogenic and are being exploited as serodiagnostic markers, drug and vaccine targets. Several Plasmodium spp. cysteine proteases have been described and the best characterized of these are the falcipains, a family of papain-family enzymes. Falcipain-2 and falcipain-3 act in concert with other proteases to hydrolyze host erythrocyte hemoglobin in the parasite food vacuole. Falcipain-1 has less similarity to the other falcipains and its physiological role in parasite asexual blood stage still remains uncertain. Immunolocalization studies using an antibody developed against the Plasmodium chabaudi recombinant chabaupain-1, the falcipain-1 ortholog, were performed confirming its cellular localization in both erythrocyte and mosquito ookinete stage. Immunostaining of chabaupain-1 preferentially in apical portion of parasite ookinete suggests that this protease may be related with parasite egression from mosquito midgut. Immune responses to chabaupain-1 were evaluated using two different adjuvants, chitosan nanoparticles and hydroxide aluminum. Mice immunized with the recombinant protein alone or in association with nanoparticles were challenged with P. chabaudi showing that immunization with the recombinant protein confers partial protection to blood stage infection in BALB/c animal model.

  14. Mating type gene homologues and putative sex pheromone-sensing pathway in arbuscular mycorrhizal fungi, a presumably asexual plant root symbiont.

    Science.gov (United States)

    Halary, Sébastien; Daubois, Laurence; Terrat, Yves; Ellenberger, Sabrina; Wöstemeyer, Johannes; Hijri, Mohamed

    2013-01-01

    The fungal kingdom displays a fascinating diversity of sex-determination systems. Recent advances in genomics provide insights into the molecular mechanisms of sex, mating type determination, and evolution of sexual reproduction in many fungal species in both ancient and modern phylogenetic lineages. All major fungal groups have evolved sexual differentiation and recombination pathways. However, sexuality is unknown in arbuscular mycorrhizal fungi (AMF) of the phylum Glomeromycota, an ecologically vital group of obligate plant root symbionts. AMF are commonly considered an ancient asexual lineage dating back to the Ordovician, approximately 460 M years ago. In this study, we used genomic and transcriptomic surveys of several AMF species to demonstrate the presence of conserved putative sex pheromone-sensing mitogen-activated protein (MAP) kinases, comparable to those described in Ascomycota and Basidiomycota. We also find genes for high mobility group (HMG) transcription factors, homologous to SexM and SexP genes in the Mucorales. The SexM genes show a remarkable sequence diversity among multiple copies in the genome, while only a single SexP sequence was detected in some isolates of Rhizophagus irregularis. In the Mucorales and Microsporidia, the sexM gene is flanked by genes for a triosephosphate transporter (TPT) and a RNA helicase, but we find no evidence for synteny in the vicinity of the Sex locus in AMF. Nonetheless, our results, together with previous observations on meiotic machinery, suggest that AMF could undergo a complete sexual reproduction cycle.

  15. Mating type gene homologues and putative sex pheromone-sensing pathway in arbuscular mycorrhizal fungi, a presumably asexual plant root symbiont.

    Directory of Open Access Journals (Sweden)

    Sébastien Halary

    Full Text Available The fungal kingdom displays a fascinating diversity of sex-determination systems. Recent advances in genomics provide insights into the molecular mechanisms of sex, mating type determination, and evolution of sexual reproduction in many fungal species in both ancient and modern phylogenetic lineages. All major fungal groups have evolved sexual differentiation and recombination pathways. However, sexuality is unknown in arbuscular mycorrhizal fungi (AMF of the phylum Glomeromycota, an ecologically vital group of obligate plant root symbionts. AMF are commonly considered an ancient asexual lineage dating back to the Ordovician, approximately 460 M years ago. In this study, we used genomic and transcriptomic surveys of several AMF species to demonstrate the presence of conserved putative sex pheromone-sensing mitogen-activated protein (MAP kinases, comparable to those described in Ascomycota and Basidiomycota. We also find genes for high mobility group (HMG transcription factors, homologous to SexM and SexP genes in the Mucorales. The SexM genes show a remarkable sequence diversity among multiple copies in the genome, while only a single SexP sequence was detected in some isolates of Rhizophagus irregularis. In the Mucorales and Microsporidia, the sexM gene is flanked by genes for a triosephosphate transporter (TPT and a RNA helicase, but we find no evidence for synteny in the vicinity of the Sex locus in AMF. Nonetheless, our results, together with previous observations on meiotic machinery, suggest that AMF could undergo a complete sexual reproduction cycle.

  16. The Novel Oomycide Oxathiapiprolin Inhibits All Stages in the Asexual Life Cycle of Pseudoperonospora cubensis - Causal Agent of Cucurbit Downy Mildew.

    Directory of Open Access Journals (Sweden)

    Yigal Cohen

    Full Text Available Oxathiapiprolin is a new oomycide (piperidinyl thiazole isoxazoline class discovered by DuPont which controls diseases caused by oomycete plant pathogens. It binds in the oxysterol-binding protein domain of Oomycetes. Growth chambers studies with detached leaves and potted plants showed remarkable activity of oxathiapiprolin against Pseudoperonospora cubensis in cucurbits. The compound affected all stages in the asexual life cycle of the pathogen. It inhibited zoospore release, cystospore germination, lesion formation, lesion expansion, sporangiophore development and sporangial production. When applied to the foliage as a preventive spray no lesions developed due to inhibition of zoospore release and cystospore germination, and when applied curatively, at one or two days after inoculation, small restricted lesions developed but no sporulation occurred. When applied later to mature lesions, sporulation was strongly inhibited. Oxathiapiprolin suppressed sporulation of P. cubensis in naturally-infected leaves. It exhibited trans-laminar activity, translocated acropetaly from older to younger leaves, and moved from the root system to the foliage. Seed coating was highly effective in protecting the developed cucumber plants against downy mildew. UV microscopy observations made with cucumber leaves infected with P. cubensis revealed that inhibition of mycelium growth and sporulation induced by oxathiapiprolin was associated with callose encasement of the haustoria.

  17. Phosphorylated and Nonphosphorylated PfMAP2 Are Localized in the Nucleus, Dependent on the Stage of Plasmodium falciparum Asexual Maturation

    Directory of Open Access Journals (Sweden)

    Farah Aida Dahalan

    2016-01-01

    Full Text Available Plasmodium falciparum mitogen-activated protein (MAP kinases, a family of enzymes central to signal transduction processes including inflammatory responses, are a promising target for antimalarial drug development. Our study shows for the first time that the P. falciparum specific MAP kinase 2 (PfMAP2 is colocalized in the nucleus of all of the asexual erythrocytic stages of P. falciparum and is particularly elevated in its phosphorylated form. It was also discovered that PfMAP2 is expressed in its highest quantity during the early trophozoite (ring form stage and significantly reduced in the mature trophozoite and schizont stages. Although the phosphorylated form of the kinase is always more prevalent, its ratio relative to the nonphosphorylated form remained constant irrespective of the parasites’ developmental stage. We have also shown that the TSH motif specifically renders PfMAP2 genetically divergent from the other plasmodial MAP kinase activation sites using Neighbour Joining analysis. Furthermore, TSH motif-specific designed antibody is crucial in determining the location of the expression of the PfMAP2 protein. However, by using immunoelectron microscopy, PPfMAP2 were detected ubiquitously in the parasitized erythrocytes. In summary, PfMAP2 may play a far more important role than previously thought and is a worthy candidate for research as an antimalarial.

  18. Phosphorylated and Nonphosphorylated PfMAP2 Are Localized in the Nucleus, Dependent on the Stage of Plasmodium falciparum Asexual Maturation

    Science.gov (United States)

    Dahalan, Farah Aida; Sidek, Hasidah Mohd; Murtey, Mogana Das; Embi, Mohammed Noor; Ibrahim, Jamaiah; Fei Tieng, Lim; Zakaria, Nurul Aiezzah

    2016-01-01

    Plasmodium falciparum mitogen-activated protein (MAP) kinases, a family of enzymes central to signal transduction processes including inflammatory responses, are a promising target for antimalarial drug development. Our study shows for the first time that the P. falciparum specific MAP kinase 2 (PfMAP2) is colocalized in the nucleus of all of the asexual erythrocytic stages of P. falciparum and is particularly elevated in its phosphorylated form. It was also discovered that PfMAP2 is expressed in its highest quantity during the early trophozoite (ring form) stage and significantly reduced in the mature trophozoite and schizont stages. Although the phosphorylated form of the kinase is always more prevalent, its ratio relative to the nonphosphorylated form remained constant irrespective of the parasites' developmental stage. We have also shown that the TSH motif specifically renders PfMAP2 genetically divergent from the other plasmodial MAP kinase activation sites using Neighbour Joining analysis. Furthermore, TSH motif-specific designed antibody is crucial in determining the location of the expression of the PfMAP2 protein. However, by using immunoelectron microscopy, PPfMAP2 were detected ubiquitously in the parasitized erythrocytes. In summary, PfMAP2 may play a far more important role than previously thought and is a worthy candidate for research as an antimalarial. PMID:27525262

  19. Glycoside Hydrolase MoGls2 Controls Asexual/Sexual Development, Cell Wall Integrity and Infectious Growth in the Rice Blast Fungus

    Science.gov (United States)

    Li, Mengying; Liu, Xinyu; Liu, Zhixi; Sun, Yi; Liu, Muxing; Wang, Xiaoli; Zhang, Haifeng; Zheng, Xiaobo; Zhang, Zhengguang

    2016-01-01

    N-linked glycosylation is a way of glycosylation for newly synthesized protein, which plays a key role in the maturation and transport of proteins. Glycoside hydrolases (GHs) are essential in this process, and are involved in processing of N-linked glycoproteins or degradation of carbohydrate structures. Here, we identified and characterized MoGls2 in Magnaporthe oryzae, which is a yeast glucosidase II homolog Gls2 and is required for trimming the final glucose in N-linked glycans and normal cell wall synthesis. Target deletion of MoGLS2 in M. oryzae resulted in a reduced mycelial growth, an increased conidial production, delayed conidial germination and loss the ability of sexual reproduction. Pathogenicity assays revealed that the ΔMogls2 mutant showed significantly decreased in virulence and infectious growth. Further studies showed that the mutant was less sensitive to salt and osmotic stress, and increased sensitivity to cell wall stresses. Additionally, the ΔMogls2 mutant showed a defect in cell wall integrity. Our results indicate that MoGls2 is a key protein for the growth and development of M. oryzae, involving in the regulation of asexual/sexual development, stress response, cell wall integrity and infectious growth. PMID:27607237

  20. Asexual reproduction in Pygospio elegans claparède (Annelida, Polychaeta) in relation to parasitism by Lepocreadium setiferoides (Miller and Northup) (Platyhelminthes, Trematoda).

    Science.gov (United States)

    McCurdy, D G

    2001-08-01

    Life-history theory predicts that parasitized hosts should alter their investment in reproduction in ways that maximize host reproductive success. I examined the timing of asexual reproduction (fragmentation and regeneration) in the polychaete annelid Pygospio elegans experimentally exposed to cercariae of the trematode Lepocreadium setiferoides. Consistent with adaptive host response, polychaetes that became infected by metacercariae of trematodes fragmented sooner than unexposed controls. Parasites were not directly associated with fission in that exposed polychaetes that did not become infected also fragmented earlier than controls. For specimens of P. elegans that were not exposed to trematodes, new fragments that contained original heads were larger than those that contained original tails, whereas original head and tail fragments did not differ in size for infected polychaetes. In infected specimens, metacercariae were equally represented in original head and tail fragments and were more likely to be found in whichever fragment was larger. Despite early reproduction, parasitism was still costly because populations of P. elegans exposed to parasites were smaller than controls when measured 8 weeks later and because exposure to cercariae reduced survivorship of newly divided polychaetes. Taken together, my results suggest that early fragmentation is a host response to minimize costs associated with parasitism.

  1. The disruption of GDP-fucose de novo biosynthesis suggests the presence of a novel fucose-containing glycoconjugate in Plasmodium asexual blood stages.

    Science.gov (United States)

    Sanz, Sílvia; López-Gutiérrez, Borja; Bandini, Giulia; Damerow, Sebastian; Absalon, Sabrina; Dinglasan, Rhoel R; Samuelson, John; Izquierdo, Luis

    2016-11-16

    Glycosylation is an important posttranslational protein modification in all eukaryotes. Besides glycosylphosphatidylinositol (GPI) anchors and N-glycosylation, O-fucosylation has been recently reported in key sporozoite proteins of the malaria parasite. Previous analyses showed the presence of GDP-fucose (GDP-Fuc), the precursor for all fucosylation reactions, in the blood stages of Plasmodium falciparum. The GDP-Fuc de novo pathway, which requires the action of GDP-mannose 4,6-dehydratase (GMD) and GDP-L-fucose synthase (FS), is conserved in the parasite genome, but the importance of fucose metabolism for the parasite is unknown. To functionally characterize the pathway we generated a PfGMD mutant and analyzed its phenotype. Although the labelling by the fucose-binding Ulex europaeus agglutinin I (UEA-I) was completely abrogated, GDP-Fuc was still detected in the mutant. This unexpected result suggests the presence of an alternative mechanism for maintaining GDP-Fuc in the parasite. Furthermore, PfGMD null mutant exhibited normal growth and invasion rates, revealing that the GDP-Fuc de novo metabolic pathway is not essential for the development in culture of the malaria parasite during the asexual blood stages. Nonetheless, the function of this metabolic route and the GDP-Fuc pool that is generated during this stage may be important for gametocytogenesis and sporogonic development in the mosquito.

  2. Effect of vacuolar ATPase subunit H (VmaH) on cellular pH, asexual cycle, stress tolerance and virulence in Beauveria bassiana.

    Science.gov (United States)

    Zhu, Jing; Zhu, Xiao-Guan; Ying, Sheng-Hua; Feng, Ming-Guang

    2017-01-01

    Vacuolar ATPase (V-ATPase) is a conserved multi-subunit protein complex that mediates intracellular acidification in fungi. Here we show functional diversity of V-ATPase subunit H (BbVmaH) in Beauveria bassiana, a filamentous fungal insect pathogen. Deletion of BbvmaH resulted in elevated vacuolar pH, increased Ca(2+) level in cytosol but not in vacuoles, accelerated culture acidification and reduced accumulation of extracellular ammonia. Aerial conidiation and submerged blastospore production were largely delayed and reduced in the deletion mutant, respectively, accompanied with a significant delay in conidial germination, alterations of conidia and blastospores in morphology, size and/or density, and severe growth defects in minimal media with different carbon and nitrogen sources. Despite null responses to osmotic, oxidative and cell wall perturbing stresses, the deletion mutant showed increased sensitivity to Ca(2+), Zn(2+) and Cu(2+) during growth while its conidia were less tolerant to a wet-heat stress at 45°C and UV-B irradiation. Intracellular glycerol and mannitol contents also decreased significantly. Its virulence to Galleria mellonella larvae was significantly attenuated when conidia were topically applied for normal cuticle infection or injected into haemocoel for cuticle-bypassing infection. All phenotypic changes were restored by targeted gene complementation. Our results indicate that BbVmaH plays an important role in sustaining not only vacuolar acidification but also cytosolic calcium accumulation, ambient pH homeostasis, in vitro asexual cycle and virulence in B. bassiana.

  3. 2-bit Flip Mutation Elementary Fitness Landscapes

    OpenAIRE

    Langdon, William

    2010-01-01

    Genetic Programming parity is not elementary. GP parity cannot be represented as the sum of a small number of elementary landscapes. Statistics, including fitness distance correlation, of Parity's fitness landscape are calculated. Using Walsh analysis the eigen values and eigenvectors of the Laplacian of the two bit flip fitness landscape are given and a ruggedness measure for elementary landscapes is proposed. An elementary needle in a haystack (NIH) landscape is g...

  4. Thermoforming of Textile Composite Pipe Fittings

    Science.gov (United States)

    Ozaki, Jun-Ichi; Manabe, Ken-Ichi

    Thermoforming of braided thermoplastic composite tubes was carried out in order to clarify the mechanism of the thermoforming process for pipe fittings such as T-shape fittings, cross fittings and two-branch fittings. The composite tube was made of a cowoven braid that consists of a carbon braid and polyamide resin, and 4-ply tubes with initial fiber orientations of 18° and 26° are used in the experiment. The branch is formed with not only the fisherman's net effect but also with moving yarns along the longitudinal direction in every forming process. The results show that the deformation behavior of the braid is very complex. Therefore, fiber orientation through forming is also greatly changed. Wall thickness at the branch decreases with increasing branch height. From these results, it is found that a fitting with complex shape can be produced by thermoforming. T-shape fittings, cross fittings and two-branch fittings are achieved by this process. It is confirmed that moving yarns along the longitudinal direction plays an important role in branch forming of pipe fittings.

  5. The Obesity Paradox and Cardiorespiratory Fitness

    Directory of Open Access Journals (Sweden)

    Paul A. McAuley

    2012-01-01

    Full Text Available Cardiorespiratory fitness as an explanation for the obesity paradox warrants further examination. We evaluated independent and joint associations of cardiorespiratory fitness and adiposity with all-cause mortality in 811 middle-aged (age, 53.3±7.2 years male never smokers without documented cardiopulmonary disease or diabetes from the Veterans Exercise Testing Study (VETS. Cardiorespiratory fitness was quantified in metabolic equivalents (METs using final treadmill speed and grade achieved on a maximal exercise test. Subjects were grouped for analysis by METs: unfit (lowest third and fit (upper two-thirds; and by body mass index (kg/m2: nonobese (18.5−29.9 and obese (≥30.0. Associations of baseline fitness and adiposity measures with all-cause mortality were determined by Cox proportional hazards analysis adjusted for age, ethnicity, hypertension, hypercholesterolemia, family history of coronary artery disease, and cardiovascular medication use. In multivariate analysis, mortality risk for obese/fit men did not differ significantly from the nonobese/fit reference group. However, compared to the reference group, nonobese and obese unfit men were 2.2 (=0.01 and 1.9 (=0.03 times more likely to die, respectively. Cardiorespiratory fitness altered the obesity paradox such that mortality risk was lower for both obese and nonobese men who were fit.

  6. Acute hernial strangulation following Wii Fit exercises.

    Science.gov (United States)

    Khan, O A; Parvaiz, A C; Vassallo, D J

    2013-01-01

    The Wii Fit is one the most popular fitness games on the market. Although this device has been linked to a number of injuries, the vast majority of these have been relatively minor musculo-skeletal complaints. We present a case of a patient who presented with an acute strangulation of a pre-existing asymptomatic paraumbilical hernia after completing a series of aerobic exercises on her Wii Fit. She required laparotomy and small bowel resection for infarcted bowel. Although a number of minor mechanical and orthopaedic injurieshave been reported with the Wii Fit, this represents the first case of a life-threatening complication associated with the use of this device.

  7. A person-environment fit approach to volunteerism : Volunteer personality fit and culture fit as predictors of affective outcomes

    NARCIS (Netherlands)

    Van Vianen, Annelies E. M.; Nijstad, Bernard A.; Voskuijl, Olga F.

    2008-01-01

    This study employed a person-environment (P-E) fit approach to explaining volunteer satisfaction, affective commitment, and turnover intentions. It was hypothesized that personality fit would explain additional variance in volunteer affective outcomes above and beyond motives to volunteer. This hypo

  8. Modified Fittings Enhance Industrial Safety

    Science.gov (United States)

    2012-01-01

    Kennedy Space Center is not only home to one of the largest buildings in the world - the massive Vehicle Assembly Building - it also hosts a number of one-of-a-kind facilities. The more than 30-mile-long campus has witnessed every launch from the Space Shuttle Launch Pad, as well as many homecomings at the Shuttle Landing Facility. Just as important, the Space Station Processing Facility (SSPF) has seen each element of the International Space Station (ISS) that passes through Kennedy before it goes into orbit. The SSPF is where ISS components are checked, tested, and adjusted before being packed into the Space Shuttle for transport. In an environment like the SSPF - spanning 457,000 square feet of processing areas, operational control rooms, laboratories, logistics areas, and office space - large workstands and equipment used to support the processing of ISS components need to be moved around the facility. One of the devices employed for this task is an air pallet. An air pallet moves on cushions of air instead of wheels. Compressed air inflates the cushions underneath the pallet and is then expelled through exhaust holes. This forms a thin film of air between the cushions and the floor, lifting the platform off the floor and making it easy to move the heavy workstands, equipment, and ISS components. Concerned with the safety of the connections on the pressurized air hoses used for the air pallets, engineers at Kennedy modified an existing commercial cam and groove fitting to control the air supply hose in the event of an accidental release of a pressurized hose. This modification prevented the hose from detaching and, propelled by compressed air, striking workers or equipment. "At the time, these were not available on commercial coupling halves, so NASA made a modification and then put them into use. If a worker were to accidentally try to remove a pressurized hose from the pallet, it no longer rapidly separated, and it safely relieved the pressure," says Paul

  9. Computation of mutual fitness by competing bacteria

    NARCIS (Netherlands)

    Keymer, J.E.; Galajda, P.; Lambert, G.; Liao, D.; Austin, R.H.

    2008-01-01

    Competing populations in shared spaces with nonrenewable resources do not necessarily wage a battle for dominance at the cost of extinction of the less-fit strain if there are fitness advantages to the presence of the other strain. We report on the use of nanofabricated habitat landscapes to study t

  10. Pilates and Physical Education: A Natural Fit

    Science.gov (United States)

    Kloubec, June; Banks, Aaron L.

    2004-01-01

    In a time period characterized by the continual decline of fitness and physical activity among American youths, Pilates can provide physical educators a unique activity that will improve fitness and stimulate the cognitive domain of today's students. Because the Pilates method of exercise encourages the development of strong and flexible muscles…

  11. FiT gets CLEAN local roots

    Energy Technology Data Exchange (ETDEWEB)

    Meehan, Chris

    2012-07-01

    Feed-in tariffs are starting to take root in the US. While there is little to no hope of a national FiT policy, a growing number of cities, like Los Angeles, Gainesville, and Sacramento and states including California and Vermont are creating their own FiTs. (orig.)

  12. United States Ski Team Fitness Testing Program.

    Science.gov (United States)

    Gettman, Larry R.

    Presented is a fitness profile designed to identify the individual athlete's strengths and weaknesses. Specifically, the areas of fitness examined are a) muscular strength; b) cardiovascular respiratory function; c) body composition; and d) motor abilities, agility, and speed. The procedures in the testing program involve the following: a) the…

  13. Physical fitness of schoolgirls with Turner syndrome

    NARCIS (Netherlands)

    Milde, K.; Tomaszewski, P.K.; Stupnicki, R.

    2013-01-01

    The aim of the study was to assess physical fitness of girls with Turner syndrome (TS) and to determine the relative contributions of age, body height, and body mass to performance in fitness tests. Girls with TS aged 10-18 years (n = 184), and age- and stature-matched healthy controls (n = 280) wer

  14. Are Physical Education Majors Models for Fitness?

    Science.gov (United States)

    Kamla, James; Snyder, Ben; Tanner, Lori; Wash, Pamela

    2012-01-01

    The National Association of Sport and Physical Education (NASPE) (2002) has taken a firm stance on the importance of adequate fitness levels of physical education teachers stating that they have the responsibility to model an active lifestyle and to promote fitness behaviors. Since the NASPE declaration, national initiatives like Let's Move…

  15. Epileptic fits under intravenous midazolam sedation.

    Science.gov (United States)

    Robb, N D

    1996-09-07

    A case is presented of a patient who suffered from recurrent epileptic fits while being treated under intravenous sedation with midazolam. Those using sedation are advised to beware of the patient who gives a history of fits being provoked in the dental environment.

  16. Expandable Purge Chambers Would Protect Cryogenic Fittings

    Science.gov (United States)

    Townsend, Ivan I., III

    2004-01-01

    Expandable ice-prevention and cleanliness-preservation (EIP-CP) chambers have been proposed to prevent the accumulation of ice or airborne particles on quick-disconnect (QD) fittings, or on ducts or tubes that contain cryogenic fluids. In the original application for which the EIP-CP chambers were conceived, there is a requirement to be able to disconnect and reconnect the QD fittings in rapid succession. If ice were to form on the fittings by condensation and freezing of airborne water vapor on the cold fitting surfaces, the ice could interfere with proper mating of the fittings, making it necessary to wait an unacceptably long time for the ice to thaw before attempting reconnection. By keeping water vapor away from the cold fitting surfaces, the EIP-CP chambers would prevent accumulation of ice, preserving the ability to reconnect as soon as required. Basically, the role of an EIP-CP chamber would be to serve as an enclosure for a flow of dry nitrogen gas that would keep ambient air away from QD cryogenic fittings. An EIP-CP chamber would be an inflatable device made of a fabriclike material. The chamber would be attached to an umbilical plate holding a cryogenic QD fitting.

  17. Definitions: Health, Fitness, and Physical Activity.

    Science.gov (United States)

    Corbin, Charles B.; Pangrazi, Robert P.; Franks, B. Don

    2000-01-01

    This paper defines a variety of fitness components, using a simple multidimensional hierarchical model that is consistent with recent definitions in the literature. It groups the definitions into two broad categories: product and process. Products refer to states of being such as physical fitness, health, and wellness. They are commonly referred…

  18. Computation of mutual fitness by competing bacteria

    NARCIS (Netherlands)

    Keymer, J.E.; Galajda, P.; Lambert, G.; Liao, D.; Austin, R.H.

    2008-01-01

    Competing populations in shared spaces with nonrenewable resources do not necessarily wage a battle for dominance at the cost of extinction of the less-fit strain if there are fitness advantages to the presence of the other strain. We report on the use of nanofabricated habitat landscapes to study t

  19. FUNdamental Integrative Training (FIT) for Physical Education

    Science.gov (United States)

    Bukowsky, Michael; Faigenbaum, Avery D.; Myer, Gregory D.

    2014-01-01

    There is a growing need for physical education teachers to integrate different types of fitness activities into their lessons in order to provide opportunities for all students to learn and practice a variety of movement skills that will enhance their physical fitness and support free-time physical activity. An increased focus on age-appropriate…

  20. Fitting PAC spectra with a hybrid algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Alves, M. A., E-mail: mauro@sepn.org [Instituto de Aeronautica e Espaco (Brazil); Carbonari, A. W., E-mail: carbonar@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (Brazil)

    2008-01-15

    A hybrid algorithm (HA) that blends features of genetic algorithms (GA) and simulated annealing (SA) was implemented for simultaneous fits of perturbed angular correlation (PAC) spectra. The main characteristic of the HA is the incorporation of a selection criterion based on SA into the basic structure of GA. The results obtained with the HA compare favorably with fits performed with conventional methods.