Sex of College Students Moderates Associations among Bedtime, Time in Bed, and Circadian Phase Angle.

Sex differences in circadian rhythms have been reported with some conflicting results. The timing of sleep and length of time in bed have not been considered, however, in previous such studies. The current study has 3 major aims: (1) replicate previous studies in a large sample of young adults for sex differences in sleep patterns and dim light melatonin onset (DLMO) phase; (2) in a subsample constrained by matching across sex for bedtime and time in bed, confirm sex differences in DLMO and phase angle of DLMO to bedtime; (3) explore sex differences in the influence of sleep timing and length of time in bed on phase angle. A total of 356 first-year Brown University students (207 women) aged 17.7 to 21.4 years (mean = 18.8 years, SD = 0.4 years) were included in these analyses. Wake time was the only sleep variable that showed a sex difference. DLMO phase was earlier in women than men and phase angle wider in women than men. Shorter time in bed was associated with wider phase angle in women and men. In men, however, a 3-way interaction indicated that phase angles were influenced by both bedtime and time in bed; a complex interaction was not found for women. These analyses in a large sample of young adults on self-selected schedules confirm a sex difference in wake time, circadian phase, and the association between circadian phase and reported bedtime. A complex interaction with length of time in bed occurred for men but not women. We propose that these sex differences likely indicate fundamental differences in the biology of the sleep and circadian timing systems as well as in behavioral choices.

Perceived discrimination against diabetics in the workplace and in work-related insurances in Switzerland.

To investigate the prevalence and risk factors of perceived diabetes-related discrimination in the workplace and in work-related insurances in persons with diabetes mellitus in Switzerland. 509 insulin-treated diabetic subjects representative of the northwestern Swiss population responded to a self-report questionnaire on perceived diabetes-related discrimination in the workplace and in work-related insurances (salary loss insurance, supplementary occupational plan). Discrimination was defined as being treated differently at least once in relation to diabetes. The reported rates of different aspects of discrimination in the workplace and in work-related insurances ranged between 5-11% and 4-15% respectively. Risk factors that independently increased the risk of not being hired due to diabetes were the presence of at least two severe hypoglycaemic events/year and relevant diabetic complications (OR 5.6 and OR 2.6 respectively; both<0.05). The presence of at least two severe hypoglycaemic events/year was also associated with an increased risk of losing one's job (OR 6.5, <0.01). Overweight or obesity were related to increased discrimination in work-related insurances (OR for denial 2.1-2.4; OR for reserve 3.9-4.4; all<0.05). Perceived diabetes-related discrimination in the workplace and by work-related insurances is a common problem. In the light of our findings the introduction of effective non-discrimination legislation for patients with chronic illnesses appears to be desirable.

Temperature-dependent turnovers in sex-determination mechanisms: a quantitative model.

Sex determination is often seen as a dichotomous process: individual sex is assumed to be determined either by genetic (genotypic sex determination, GSD) or by environmental factors (environmental sex determination, ESD), most often temperature (temperature sex determination, TSD). We endorse an alternative view, which sees GSD and TSD as the ends of a continuum. Both effects interact a priori, because temperature can affect gene expression at any step along the sex-determination cascade. We propose to define sex-determination systems at the population- (rather than individual) level, via the proportion of variance in phenotypic sex stemming from genetic versus environmental factors, and we formalize this concept in a quantitative-genetics framework. Sex is seen as a threshold trait underlain by a liability factor, and reaction norms allow modeling interactions between genotypic and temperature effects (seen as the necessary consequences of thermodynamic constraints on the underlying physiological processes). As this formalization shows, temperature changes (due to e.g., climatic changes or range expansions) are expected to provoke turnovers in sex-determination mechanisms, by inducing large-scale sex reversal and thereby sex-ratio selection for alternative sex-determining genes. The frequency of turnovers and prevalence of homomorphic sex chromosomes in cold-blooded vertebrates might thus directly relate to the temperature dependence in sex-determination mechanisms.

A cryptic heterogametic transition revealed by sex-linked DNA markers in Palearctic green toads.

In sharp contrast to birds and mammals, most cold-blooded vertebrates have homomorphic (morphologically undifferentiated) sex chromosomes. This might result either from recurrent X-Y recombination (occurring e.g. during occasional events of sex reversal) or from frequent turnovers (during which sex-determining genes are overthrown by new autosomal mutations). Evidence for turnovers is indeed mounting in fish, but very few have so far been documented in amphibians, possibly because of practical difficulties in identifying sex chromosomes. Female heterogamety (ZW) has long been established in Bufo bufo, based on sex reversal and crossing experiments. Here, we investigate a sex-linked marker identified from a laboratory cross between Palearctic green toads (Bufo viridis subgroup). The F(1) offspring produced by a female Bufo balearicus and a male Bufo siculus were phenotypically sexed, displaying an even sex ratio. A sex-specific marker detected in highly reproducible AFLP genotypes was cloned. Sequencing revealed a noncoding, microsatellite-containing fragment. Reamplification and genotyping of families of this and a reciprocal cross showed B. siculus to be male heterogametic (XY) and suggested the same system for B. balearicus. Our results thus reveal a cryptic heterogametic transition within bufonid frogs and help explain patterns of hybrid fitness within the B. viridis subgroup. Turnovers of genetic sex-determination systems may be more frequent in amphibians than previously thought and thus contribute to the prevalence of homomorphic sex chromosomes in this group.

Scale-specific sex-biased dispersal in the Valais shrew unveiled by genetic variation on the Y chromosome, autosomes, and mitochondrial DNA.

We investigated sex specificities in the evolutionary processes shaping Y chromosome, autosomes, and mitochondrial DNA patterns of genetic structure in the Valais shrew (Sorex antinorii), a mountain dwelling species with a hierarchical distribution. Both hierarchical analyses of variance and isolation-by-distance analyses revealed patterns of population structure that were not consistent across maternal, paternal, and biparentally inherited markers. Differentiation on a Y microsatellite was lower than expected from the comparison with autosomal microsatellites and mtDNA, and it was mostly due to genetic variance among populations within valleys, whereas the opposite was observed on other markers. In addition, there was no pattern of isolation by distance for the Y, whereas there was strong isolation by distance on mtDNA and autosomes. We use a hierarchical island model of coancestry dynamics to discuss the relative roles of the microevolutionary forces that may induce such patterns. We conclude that sex-biased dispersal is the most important driver of the observed genetic structure, but with an intriguing twist: it seems that dispersal is strongly male biased at large spatial scale, whereas it is mildly biased in favor of females at local scale. These results add to recent reports of scale-specific sex-biased dispersal patterns, and emphasize the usefulness of the Y chromosome in conjunction with mtDNA and autosomes to infer sex specificities.

Calidad de vida y percepción de la desigualdad de la mujer en la ciudad de Girona = Quality of life and inequality perception’s of women in the city of Girona

La igualdad de oportunidades para las mujeres, como factor clave para avanzar en la consecución de calidad de vida preocupa hoy en día a la sociedad en general y alas instituciones en particular. Antes de la elaboración de programas de intervención social es necesario conocer las percepciones de las propias mujeres acerca de sus problemas y de sus necesidades. Siguiendo esta línea de pensamiento presentamos un trabajo empírico en el que analizamos las percepciones de las mujeres de la ciudad de Girona, centrándonos en dos aspectos de manera particular: la percepción de calidad de vida proporcionada por su ciudad y la percepción de desigualdad de oportunidades y/o de discriminación. Los principales resultados, obtenidos a partir de las respuestas a un cuestionario auto-administrado, y proporcionados por una muestra de mujeres seleccionadas aleatoriamente a partir de un muestreo estratificado geográficamente, indican que en general están satisfechas con su ciudad aunque detectamos las principales causas de insatisfacción. Por otra parte, tas principales fuentes de desigualdad se refieren al mundo laboral (menos salario por el mismo trabajo, dificultades de encontrar trabajo si tienen hijos o si son ya mayores), y en la actitud general de la sociedad en el sentido de tener que cumplir el papel que tradicionalmente se les ha asignado

Sex allocation conflict in ants: when the queen rules.

Insect societies are paramount examples of cooperation, yet they also harbor internal conflicts whose resolution depends on the power of the opponents. The male-haploid, female-diploid sex-determining system of ants causes workers to be more related to sisters than to brothers, whereas queens are equally related to daughters and sons. Workers should thus allocate more resources to females than to males, while queens should favor an equal investment in each sex. Female-biased sex allocation and manipulation of the sex ratio during brood development suggest that workers prevail in many ant species. Here, we show that queens of Formica selysi strongly influenced colony sex allocation by biasing the sex ratio of their eggs. Most colonies specialized in the production of a single sex. Queens in female-specialist colonies laid a high proportion of diploid eggs, whereas queens in male-specialist colonies laid almost exclusively haploid eggs, which constrains worker manipulation. However, the change in sex ratio between the egg and pupae stages suggests that workers eliminated some male brood, and the population sex-investment ratio was between the queens' and workers' equilibria. Altogether, these data provide evidence for an ongoing conflict between queens and workers, with a prominent influence of queens as a result of their control of egg sex ratio.

Sex-differential herbivory in androdioecious Mercurialis annua.

Males of plants with separate sexes are often more prone to attack by herbivores than females. A common explanation for this pattern is that individuals with a greater male function suffer more from herbivory because they grow more quickly, drawing more heavily on resources for growth that might otherwise be allocated to defence. Here, we test this 'faster-sex' hypothesis in a species in which males in fact grow more slowly than hermaphrodites, the wind-pollinated annual herb Mercurialis annua. We expected greater herbivory in the faster-growing hermaphrodites. In contrast, we found that males, the slower sex, were significantly more heavily eaten by snails than hermaphrodites. Our results thus reject the faster-sex hypothesis and point to the importance of a trade-off between defence and reproduction rather than growth.

Modulation in Wistar rats of blood corticosterone compartmentation by sex and prior exposure to a cafeteria diet

In the metabolic syndrome, glucocorticoid activity is increased, but circulating levels show little change. Most of blood glucocorticoids are bound to corticosteroid-binding globulin (CBG), which liver expression and circulating levels are higher in females than in males. Since blood hormones are also bound to blood cells, and the size of this compartment is considerable for androgens and estrogens, we analyzed whether sex or eating a cafeteria diet altered the compartmentation of corticosterone in rat blood. The main corticosterone compartment in rat blood is that specifically bound to plasma proteins, with smaller compartments bound to blood cells or free. Cafeteria diet increased the expression of liver CBG gene, binding plasma capacity and the proportion of blood cell-bound corticosterone. There were marked sex differences in blood corticosterone compartmentation in rats, which were unrelated to testosterone. The use of a monoclonal antibody ELISA and a polyclonal Western blot for plasma CBG compared with both specific plasma binding of corticosterone and CBG gene expression suggested the existence of different forms of CBG, with varying affinities for corticosterone in males and females, since ELISA data showed higher plasma CBG for males, but binding and Western blot analyses (plus liver gene expression) and higher physiological effectiveness for females. Good cross- reactivity to the antigen for polyclonal CBG antibody suggests that in all cases we were measuring CBG.The different immunoreactivity and binding affinity may help explain the marked sex-related differences in plasma hormone binding as sex-linked different proportions of CBG forms.

Body mass index and risk of head and neck cancer in a pooled analysis of case-control studies in the International Head and Neck Cancer Epidemiology (INHANCE) Consortium.

BACKGROUND: Head and neck cancer (HNC) risk is elevated among lean people and reduced among overweight or obese people in some studies; however, it is unknown whether these associations differ for certain subgroups or are influenced by residual confounding from the effects of alcohol and tobacco use or by other sources of biases. METHODS: We pooled data from 17 case-control studies including 12 716 cases and the 17 438 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for associations between body mass index (BMI) at different ages and HNC risk, adjusted for age, sex, centre, race, education, tobacco smoking and alcohol consumption. RESULTS: Adjusted ORs (95% CIs) were elevated for people with BMI at reference (date of diagnosis for cases and date of selection for controls) 25.0-30.0 kg/m(2) (0.52, 0.44-0.60) and BMI >/=30 kg/m(2) (0.43, 0.33-0.57), compared with BMI >18.5-25.0 kg/m(2). These associations did not differ by age, sex, tumour site or control source. Although the increased risk among people with BMI 25 kg/m(2) was present only in smokers and drinkers. CONCLUSIONS: In our large pooled analysis, leanness was associated with increased HNC risk regardless of smoking and drinking status, although reverse causality cannot be excluded. The reduced risk among overweight or obese people may indicate body size is a modifier of the risk associated with smoking and drinking. Further clarification may be provided by analyses of prospective cohort and mechanistic studies.

Sex ratio and Wolbachia infection in the ant Formica exsecta.

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

Sex-chromosome evolution of Palearctic tree frogs in space and time

Sexual reproduction is nearly universal in eukaryotes and genetic determination of sex prevails among animals. The astonishing diversity of sex-determining systems and sex chromosomes is yet bewildering. Some taxonomic groups possess conserved and dimorphic sex chromosomes, involving a functional copy (e.g. mammals' X, birds' Z) and a degenerated copy (mammals' Y, birds' W), implying that sex- chromosomes are expected to decay. In contrast, others like amphibians, reptiles and fishes yet maintained undifferentiated sex chromosomes. Why such different evolutionary trajectories? In this thesis, we empirically test and characterize the main hypotheses proposed to prevent the genetic decay of sex chromosomes, namely occasional X-Y recombination and frequent sex-chromosome transitions, using the Palearctic radiation of Hyla tree frogs as a model system. We take a phylogeographic and phylogenetic approach to relate sex-chromosome recombination, differentiation, and transitions in a spatial and temporal framework. By reconstructing the recent evolutionary history of the widespread European tree frog H. arborea, we showed that sex chromosomes can recombine in males, preventing their differentiation, a situation that potentially evolves rapidly. At the scale of the entire radiation, X-Y recombination combines with frequent transitions to prevent sex-chromosome degeneration in Hyla: we traced several turnovers of sex-determining system within the last 10My. These rapid changes seem less random than usually assumed: we gathered evidences that one chromosome pair is a sex expert, carrying genes with key role in animal sex determination, and which probably specialized through frequent reuse as a sex chromosome in Hyla and other amphibians. Finally, we took advantage of secondary contact zones between closely-related Hyla lineages to evaluate the consequences of sex chromosome homomorphy on the genetics of speciation. In comparison with other systems, the evolution of sex chromosomes in Hyla emphasized the existence of consistent evolutionary patterns within the chaotic diversity of flexibility of cold-blooded vertebrates' sex-determining systems, and provides insights into the evolution of recombination. Beyond sex-chromosome evolution, this work also significantly contributed to speciation, phylogeography and applied conservation research. -- La reproduction sexuée est quasi-universelle chez les eucaryotes et le sexe est le plus souvent déterminé génétiquement au sein du règne animal. L'incroyable diversité des systèmes de reproduction et des chromosomes sexuels est particulièrement étonnante. Certains groupes taxonomiques possèdent des chromosomes sexuels dimorphiques et très conservés, avec une copie entièrement fonctionnelle (ex : le X des mammifères, le Z des oiseaux) et une copie dégénérée (ex : le Y des mammifères, le W des oiseaux), suggérant que les chromosomes sexuels sont voués à se détériorer. Cependant les chromosomes sexuels d'autres groupes tels que les amphibiens, les reptiles et les poissons sont pour la plupart indifférenciés. Comment expliquer des trajectoires évolutives si différentes? Au cours de cette thèse, nous avons étudié empiriquement les processus évolutifs pouvant maintenir les chromosomes sexuels intacts, à savoir la recombinaison X-Y occasionnel ainsi que les substitutions fréquentes de chromosomes sexuels, en utilisant les rainettes Paléarctiques du genre Hyla comme modèle d'étude. Nous avons adopté une approche phylogéographique et phylogénétique pour appréhender les événements de recombinaison, de différenciation et de transitions de chromosomes sexuels dans un contexte spatio-temporel. En retraçant l'histoire évolutive récente de la rainette verte H. arborea, nous avons mis en évidence que les chromosomes sexuels pouvaient recombiner chez les mâles, empêchant ainsi leur différenciation, et que ce processus avait le potentiel d'évoluer très rapidement. A l'échelle plus globale de la radiation, il apparait que les phénomènes de recombinaison X-Y soient également accompagnés de substitutions de chromosomes sexuels, et participent de concert au maintien de chromosomes sexuels intacts dans les populations: le système de détermination du sexe des rainettes a changé plusieurs fois au cours des 10 derniers millions d'années. Ces transitions fréquentes ne semblent pas aléatoires: nous avons identifié une paire de chromosomes qui présente des caractéristiques présageant d'une spécialisation dans le déterminisme du sexe (notamment car elle possède des gènes importants pour cette fonction), et qui a été réutilisée plusieurs fois comme tel chez les rainettes ainsi que d'autres amphibiens. Enfin, nous avons étudié l'hybridation entre différentes espèces dans leurs zones de contact, afin d'évaluer si l'absence de différenciation entre X et Y jouaient un rôle dans les processus génétiques de spéciation. Outre son intérêt pour la compréhension de l'évolution des chromosomes sexuels, ce travail contribue de manière significative à d'autres domaines de recherche tels que la spéciation, la phylogéographie, ainsi que la biologie de la conservation.

Teaching how to learn with a wiki in Primary Education: what classroom interaction can tell us

Understanding how wikis are used to support collaborative learning is an important concern for researchers and teachers. Adopting a discourse analytic approach, this paper attempts to understand the teaching processes when a wiki is embedded in a science project in primary education to foster collaborative learning. Through studying interaction between the teacher and students, our findings identify ways in which the teacher prompts collaborative learning but also shed light on the difficulties for the teacher in supporting student collective collaboration. It is argued that technological wiki features supporting collaborative learning can only be realized if teacher talk and pedagogy are aligned with the characteristics of wiki collaborative work: the freedom of students to organize and participate by themselves, creating dialogic space and promoting student participation. We argue that a dialogic approach for examining interaction can be used to help to design a more effective pedagogic approach in the use of wikis in education, to shift into Web 2.0 learning paradigm and to equip learners with the competences they need to participate in knowledge co-construction.

Wiki-supported collaborative learning in primary education. How a dialogic space is created for thinking together

This paper explores how wikis may be used to support primary education students’ collaborative interaction and how such an interaction process can be characterised. The overall aim of this study is to analyse the collaborative processes of students working together in a wiki environment, in order to see how primary students can actively create a shared context for learning in the wiki. Educational literature has already reported that wikis may support collaborative knowledge-construction processes, but in our study we claim that a dialogic perspective is needed to accomplish this. Students must develop an intersubjective orientation towards each others’ perspectives, to co-construct knowledge about a topic. For this purpose, our project utilised a ‘Thinking Together’ approach to help students develop an intersubjective orientation towards one another and to support the creation of a ‘dialogic space’ to co-construct new understanding in a wiki science project. The students’ asynchronous interaction process in a primary classroom -- which led to the creation of a science text in the wiki -- was analysed and characterised, using a dialogic approach to the study of CSCL practices. Our results illustrate how the Thinking Together approach became embedded within the wiki environment and in the students’ collaborative processes. We argue that a dialogic approach for examining interaction can be used to help design more effective pedagogic approaches related to the use of wikis in education and to equip learners with the competences they need to participate in the global knowledge-construction era.

Qualitative social differentiation in tertiary education in Spain

[cat] En aquest treball, s'estudia si la hipòtesi de la desigualtat efectivament mantinguda “effectively maintained inequality” es cumpleix a Espanya. Es postula que en les transicions terciàries a Espanya, les influències dels pares no es manifesten tant a través de la probabilitat de fer la transició, sinó més aviat a través de les diferències qualitatives associades a aquesta transició en termes de les qualitats dels programes educatius. Analitzem dues característiques qualitatives dels estudis universitaris: la durada del programa i el seu prestigi acadèmic. Identifiquem per a quins individus la influència parental és més important en cada cas.