Genetic clusters and sex-biased gene flow in a unicolonial Formica ant.

BACKGROUND: Animal societies are diverse, ranging from small family-based groups to extraordinarily large social networks in which many unrelated individuals interact. At the extreme of this continuum, some ant species form unicolonial populations in which workers and queens can move among multiple interconnected nests without eliciting aggression. Although unicoloniality has been mostly studied in invasive ants, it also occurs in some native non-invasive species. Unicoloniality is commonly associated with very high queen number, which may result in levels of relatedness among nestmates being so low as to raise the question of the maintenance of altruism by kin selection in such systems. However, the actual relatedness among cooperating individuals critically depends on effective dispersal and the ensuing pattern of genetic structuring. In order to better understand the evolution of unicoloniality in native non-invasive ants, we investigated the fine-scale population genetic structure and gene flow in three unicolonial populations of the wood ant F. paralugubris. RESULTS: The analysis of geo-referenced microsatellite genotypes and mitochondrial haplotypes revealed the presence of cryptic clusters of genetically-differentiated nests in the three populations of F. paralugubris. Because of this spatial genetic heterogeneity, members of the same clusters were moderately but significantly related. The comparison of nuclear (microsatellite) and mitochondrial differentiation indicated that effective gene flow was male-biased in all populations. CONCLUSION: The three unicolonial populations exhibited male-biased and mostly local gene flow. The high number of queens per nest, exchanges among neighbouring nests and restricted long-distance gene flow resulted in large clusters of genetically similar nests. The positive relatedness among clustermates suggests that kin selection may still contribute to the maintenance of altruism in unicolonial populations if competition occurs among clusters.

Wandering, verbally and physically abusive behaviour and their relation with pain in nursing homes residents

Backgrounds:¦Behavioural and psychological symptoms of dementia (BPSD) include, among others, hallucinations, delusions, depression, euphoria, agitation, aggression, sexual desinhibition, sleep disturbances, and apathy (1). To our knowledge, surprisingly few studies looked into the possible association between pain and BPSD in nursing home residents. Given this dearth of studies, we wondered whether or not there is an association, in nursing home residents, between pain and BPSD, in particular wandering as well as verbally and physically abusive behaviour, and whether or not this possible association changes with the degree of cognitive impairment.¦Method:¦All nursing home residents in the three Swiss cantons Aargau, Basel-City, and Solothurn (corresponding to 13.5%¦of the total Swiss population) receive a Resident Assessment Instrument Minimum Data Set (RAI-MDS)¦assessment within the first two weeks upon entry. This yielded a total sample of 16'430 nursing home residents considering that the residents' assessment took place between 1997 and 2007 and that we only took into account the admission RAI-MDS assessment. Only residents for whom data on pain was recorded were included in the study (n = 16'183).¦Results:¦Wandering correlated significantly with pain although the effect size was small (Spearman correlation coefficient = 0.052; p = 0.000), a result very similar to that found for VAB (Spearman correlation coefficient = 0.034; p = 0.000) and PAB (Spearman correlation coefficient = 0.043; p = 0.000). Likewise, using linear regression analyses, pain was very significantly associated with any of the three BPSD considered, but it predicted astonishingly little of the¦variance observed (wandering: B = 0.036; p = 0.000; R2 = 0.002; VAB: B = 0.021; p = 0.000; R2 = 0.001 PAB: B = 0.012; p = 0.000; R2 = 0.001). The interaction of pain and cognition had a significant effect on the three BPSD, suggesting that cognition was a moderator of the relationship between pain and all three behaviours.¦Conclusion:¦Wandering behaviours, VAB and PAB seem to be predicted by many factors. Although pain predicts only a small part of variance of these behaviours, it still remains important to recognise and treat pain in order to reduce these behaviours at least a little both in intensity and frequency. Given the dearth of studies and their somewhat contradictory results, further studies ought to investigate the role, the type and localisation of pain might play on the expression of different BPSD or how residents suffering from dementia perceive pain.

Obstacles à une gestion pertinente et efficace de l'absentéisme

Un processus de réinsertion professionnelle pertinent sous-entend une gestion pertinente des travailleurs absents et leur prise en charge rapide et coordonnée. Dans le cadre d'un projet de recherche, des problèmes lors de l'identification des cas ont été rencontrés. Différents éléments faisant clairement obstacle au processus de sélection instauré dans les entreprises partenaires ont été mis en évidence. Ceux-ci doivent être considérés de manière plus large comme des freins à l'dentification précoce des individus à risque d'invalidité et ainsi au processus de réinsertion professionnelle. [Auteurs]

Association between non-medical prescription drug use and personality traits among young Swiss men.

AIM: To investigate the relationships between six classes of non-medical prescription drug use (NMPDU) and five personality traits. METHODS: Representative baseline data on 5777 Swiss men around 20 years old were taken from the Cohort Study on Substance Use Risk Factors. NMPDU of opioid analgesics, sedatives/sleeping pills, anxiolytics, antidepressants, beta-blockers and stimulants over the previous 12 months was measured. Personality was assessed using the Brief Sensation Seeking Scale; attention deficit-hyperactivity (ADH) using the Adult Attention-Deficit-Hyperactivity Disorder Self-Report Scale; and aggression/hostility, anxiety/neuroticism and sociability using the Zuckerman-Kuhlmann Personality Questionnaire. Logistic regression models for each personality trait were fitted, as were seven multiple logistic regression models predicting each NMPDU adjusting for all personality traits and covariates. RESULTS: Around 10.7% of participants reported NMPDU in the last 12 months, with opioid analgesics most prevalent (6.7%), then sedatives/sleeping pills (3.0%), anxiolytics (2.7%), and stimulants (1.9%). Sensation seeking (SS), ADH, aggression/hostility, and anxiety/neuroticism (but not sociability) were significantly positively associated with at least one drug class (OR varied between 1.24, 95%CI: 1.04-1.48 and 1.86, 95%CI: 1.47-2.35). Aggression/hostility, anxiety/neuroticism and ADH were significantly and positively related to almost all NMPDU. Sociability was inversely related to NMPDU of sedatives/sleeping pills and anxiolytics (OR, 0.70; 95%CI: 0.51-0.96 and OR, 0.64; 95%CI: 0.46-0.90, respectively). SS was related only to stimulant use (OR, 1.74; 95%CI: 1.14-2.65). CONCLUSION: People with higher scores for ADH, aggression/hostility and anxiety/neuroticism are at higher risk of NMPDU. Sociability appeared to protect from NMPDU of sedatives/sleeping pills and anxiolytics.

Individual monitoring of internal exposure for nuclear medicine workers in Switzerland.

Monitoring of internal exposure for nuclear medicine workers requires frequent measurements due to the short physical half-lives of most radionuclides used in this field. The aim of this study was to develop screening measurements performed at the workplace by local staff using standard laboratory instrumentation, to detect whether potential intake has occurred. Such measurements do not enable to determine the committed effective dose, but are adequate to verify that a given threshold is not exceeded. For radioiodine, i.e. (123)I, (124)I, (125)I and (131)I, a calibrated surface contamination monitor is placed in front of the thyroid to detect whether the activity threshold has been exceeded. For radionuclides with very short physical half-lives (≤6 h), such as (99m)Tc and those used in positron emission tomography  imaging, i.e. (11)C, (15)O, (18)F and (68)Ga, screening procedures consist in performing daily measurements of the ambient dose rate in front of the abdomen. Other gamma emitters used for imaging, i.e. (67)Ga, (111)In and (201)Tl, are measured with a scintillation detector located in front of the thorax. For pure beta emitters, i.e. (90)Y and (169)Er, as well as beta emitters with low-intensity gamma rays, i.e. (153)Sm, (177)Lu, (186)Re and (188)Re, the procedure consists in measuring hand contamination immediately after use. In Switzerland, screening procedures have been adopted by most nuclear medicine services since such measurements enable an acceptable monitoring while taking into account practical and economic considerations.

The combination of social and personal contexts affects dominance hierarchy development in shore crabs, Carcinus maenas

Many animals that live in groups maintain competitive relationships, yet avoid continual fighting, by forming dominance hierarchies. We compare predictions of stochastic, individual-based models with empirical experimental evidence using shore crabs to test competing hypotheses regarding hierarchy development. The models test (1) what information individuals use when deciding to fight or retreat, (2) how past experience affects current resource-holding potential, and (3) how individuals deal with changes to the social environment. First, we conclude that crabs assess only their own state and not their opponent's when deciding to fight or retreat. Second, willingness to enter, and performance in, aggressive contests are influenced by previous contest outcomes. Winning increases the likelihood of both fighting and winning future interactions, while losing has the opposite effect. Third, when groups with established dominance hierarchies dissolve and new groups form, individuals reassess their ranks, showing no memory of previous rank or group affiliation. With every change in group composition, individuals fight for their new ranks. This iterative process carries over as groups dissolve and form, which has important implications for the relationship between ability and hierarchy rank. We conclude that dominance hierarchies emerge through an interaction of individual and social factors, and discuss these findings in terms of an underlying mechanism. Overall, our results are consistent with crabs using a cumulative assessment strategy iterated across changes in group composition, in which aggression is constrained by an absolute threshold in energy spent and damage received while fighting.

Bilan de santé à 50 ans: formation des médecins praticiens en prévention clinique

En 1994, l'entreprise Ciba SC située à Monthey (canton du Valais, Suisse) a décidé d'élargir ses actions de promotion de la santé en offrant à ses collaborateurs de 50 ans une consultation médicale intitulée "Bilan de santé". 1.1. Historique. 1.2. Prolongation du projet auprès des praticiens. 2. Population et méthodes. 2.1. Médecins et module de formation : Réalisation du "Module de consultation des 50 ans en pratique ambulatoire, remboursement, évaluation du module de formation. 2.2. Collaborateurs des usines de Monthey. 2.3. Réalisation pratique et déroulement de la consultation. 2.4. Evaluation de l'impact du projet. 3. Résultats. 3.1. Participation, habitudes de vie et santé des participants : tabagisme, alimentation, activité physique, alcool, drogues, médicaments, situation de vie et état psychique, prévention routière, vaccinations, hypercholestérolémie, données cliniques, facteurs de risques identifiés et reportés par le médecin. 3.2. Evaluation, l'opinion des patients : satisfaction, conséquences sur les habitudes de vie. 3.3. Evaluation, l'opinion des praticiens : satisfaction, impact et souhaits perçus chez les médecins, déroulement de la consultation, examens de laboratoire, rémunération. 4. Discussion. 5. Conclusion.

Assessment of particulate exposure and surface characteristics in association with urinary levels of 8-hydroxy-2'-deoxyguanosine, considered as marker of oxidative stress

Epidemiological studies have demonstrated that exposure to fine particles is associated to adverse health effects, including cancer, respiratory and cardiovascular diseases. However, mechanisms by which particles induce health effects remain unclear. According to one of the most investigated hypotheses, particles cause adverse effects through the production of reactive oxygen species (ROS), which are very hazardous compounds able to attack directly biological structures, including the DNA strand or the lipid bilayer of the cells. If the defense mechanisms, constituted of antioxidants, are not able to counter ROS, then these compounds will cause in the body a range of oxidation reactions called "oxidative stress". The aim of the present research project was to better understand mechanisms by which exposure to fine particles induces oxidative stress. The first point of this project was to check whether exposure to high levels of fine particles is directly linked to oxidative stress, and whether this oxidative stress is accompanied by the activation of the defense mechanisms (antioxidants). The second point was to study the role played by the particle surface characteristics in the oxidative stress process. For that purpose, a study was conducted in bus depots with the participation of 40 mechanics. First, occupational exposure to particles (PM4) and to other pollutants (NOx, O3) was measured over a two-day period. Then, urine samples of mechanics were collected in order to measure levels of 8-hydroxy-2'-deoxyguanosine (8OHdG) and antioxidants. 8OHdG is a molecule formed by the oxidation of DNA and allowing to assess the oxidative stress status of the mechanics. Finally, particles were collected on filters, and functional groups located on the particle surface were analyzed in the laboratory using a Knudsen flow reactor. This technique allows not only to quantify functional groups on the particle surface, but also to measure the reaction kinetics. Results obtained during the field campaign in bus depots showed that mechanics were exposed to rather low levels of PM4 (20-85 μg/m3) and of pollutants (NOx: 100-1000 ppb; O3: <15 ppb). However, despite this low exposure, urinary levels of the oxidative stress biomarker (8OHdG) increased significantly for non-smoking workers over a two-day period of shift. This oxidative stress was accompanied by an increase of antioxidants, indicating the activation of defense mechanisms. On the other hand, the analysis of functional groups on the particle surface showed important differences, depending on the workplace, the date and the activities of workers. The particle surface contained simultaneously antagonistic functional groups which did not undergo internal reactions (such as acids and bases), and was usually characterized by a high density of carbonyl functions and a low density of acidic sites. Reaction kinetics measured using the Knudsen flow reactor pointed out fast reactions of oxidizable groups and slow reactions of acidic sites. Several exposure parameters were significantly correlated with the increase of the oxidative stress status: the presence of acidic sites, carbonyl functions and oxidizable groups on the particle surface; reaction kinetics of functional groups on the particle surface; particulate iron and copper concentrations; and NOx concentration.

Epidemiologic study of low back pain in 1398 Swiss conscripts between 1985 and 1992.

The two objectives of this study, based on a sample of 1398 Swiss army conscripts born in 1966 who participated in a first study in 1985, were to measure the prevalence of low back pain (LBP) at age 26 years and its incidence between 19 and 26 years and to analyze the relationship between LBP and occupational, nonoccupational, or physical risk factors. The lifetime prevalence of LBP at age 26 was 69.1% and the incidence of LBP between 19 and 26, 44.7%. A history of LBP or a pathological physical examination result at age 19 did not predict the prevalence or the incidence at age 26. Standing, twisting, vibration, and heavy work were significantly associated with chronic LBP and/or the 1-year prevalence of LBP at age 26 (P<0.05). The evolution of sport and leisure-time activities from age 19 to 26 did not differ between people with or without LBP. The ergonomic organization of the workplace should represent a major element of future strategies to prevent LBP.

Influence of the number of queens on nestmate recognition and attractiveness of queens to workers in the Argentine ant, Iridomyrmex humilis (Mayr)

To investigate the influence of the number of queens per colony on nestmate recognition in Iridomyrmex humilis, comparative assays were performed to study the attraction of workers to queens. These assays demonstrated that a phenomenon of recognition is superimposed on the attraction of workers to queens. Workers could discriminate non-nestmate queens from their nestmate queen to which they were significantly more attracted. This discrimination is probably based on the learning by workers of queen and colony odour. The level of attraction of workers to non-nestmate queens was similar in monogynous and polygynous colonies, whereas the level of attraction of workers to nestmate queens was significantly lower in polygynous colonies. This difference in the level of attraction of workers to nestmate queens almost certainly resulted from a lower efficiency in nestmate recognition in polygynous colonies. It is hypothesized that the mixture of several pheromonal sources produced by less related individuals in polygynous colonies may result in a less distinct colony odour than in monogynous colonies. The results are discussed with regard to some implications of polygyny and particularly to the loss of intercolonial aggression in I. humilis as well as in other polygynous ant species

Impact of social structure variation on population genetics, social conflicts and life histories in ants

Summary The evolution of social structures and breeding systems in animals is a complex process that combines ecological, genetical and social factors. This thesis sheds light on important changes in population genetics, life-history and social behavior that are associated with variation in social structure in ants. The socially polymorphic ant Formica selysi was chosen as the model organism because single- and multiple-queen colonies occur in close proximity within a single large population. The shift from single- to multiple-queen colonies is generally associated with profound changes in dispersal behavior and mode of colony founding. In chapter 1, we examine the genetic consequences of variation in social structure at both the colony and population levels. A detailed microsatellite analysis reveals that both colony types have similar mating systems, with few or no queen turnover. Furthermore, the complete lack of genetic differentiation observed between single- and multiple-queen colonies provides no support to the hypothesis that change in queen number leads to restricted gene flow between social forms. Besides changes in the genetic composition of the colony, the variation in the number of queens per colony is associated with changes in a network of behavioral and life-history traits that have been described as forming a "polygyny syndrome". In chapter 2, we demonstrate that multiple-queen colonies profoundly differ from single-queen ones in terms of size, nest density and lifespan of colonies, in weight of queens produced, as well as in allocation to reproductive individuals relative to workers. These multifaceted changes in life-history traits can provide various fitness benefits to members of multiple-queen colonies. Increasing the number of queens in a colony usually results in a decreased level of aggression towards non-nestmates. The phenotype matching hypothesis predicts that, compared to single-queen colonies, multiple-queen colonies have more diverse genetically-derived cues used for recognition, resulting in a lower ability to discriminate non-nestmates. In sharp contrast to this hypothesis, we show in chapter 3 that single- and multiple-queen colonies exhibit on average similar levels of aggression. Moreover, stronger aggression is recorded between colonies of different social structure than between colonies of the same social structure. Several hypotheses propose that the evolution of multiple-queen colonies is at least partly due to benefits resulting from an increase in colony genetic diversity. The task-efficiency hypothesis holds that genetic variation improves task performance due to a more complete or more sensitive expression of the genetically-based division of labor. In .chapter 4, we evaluate if higher colony genetic diversity increases worker size polymorphism and thus may improve division of labor. We show that despite the fact that worker size has a heritable component, higher levels of genetic diversity do not result in more polymorphic workers. The smaller size and lower polymorphism levels of workers of multiple-queen colonies compared to single-queen ones further indicate that an increase in colony genetic diversity does not increase worker size polymorphism but might improve colony homeostasis. In chapter 5, we provide clear evidence for an ongoing conflict between queens and workers on sex allocation, as predicted by kin selection theory. Our data show that queens of F. selysi strongly influence colony sex allocation by biasing the sex ratio of their eggs. However, there is also evidence that workers eliminated some male brood, resulting in a population sex-investment ratio that is between the queens' and workers' equilibria. Résumé L'évolution des structures sociales et systèmes d'accouplement chez les animaux est un processus complexe combinant à la fois des facteurs écologiques, génétiques et sociaux. Cette thèse met en lumière des changements importants dans la génétique des populations, les traits d'histoire de vie et les comportements sociaux qui sont associés à des variations de structure sociale chez les fourmis. Durant ce travail, nous avons étudié une population de Formica selysi composée à la fois de colonies à une reine et de colonies à plusieurs reines. La transition de colonie à une reine à colonie à plusieurs reines est généralement associée à des changements profonds dans le comportement de dispersion ainsi que le mode de fondation des sociétés. Dans le chapitre 1, nous examinons les conséquences génétiques de la variation de structure sociale tant au niveau de la colonie qu'au niveau de la population. Une analyse détaillée à l'aide de marqueurs microsatellites nous révèle que les deux types de colonies ont des systèmes d'accouplements similaires avec peu ou pas de renouvellement de reines. L'absence totale de différenciation génétique entre les colonies à une et à plusieurs reines n'apporte aucun support à l'hypothèse selon laquelle un changement dans le nombre de reines conduit à un flux de gènes restreint entre les deux formes sociales. A côté de changements dans la composition génétique de la colonie, la variation du nombre de reines dans une colonie est associée à une multitude de changements comportementaux et de traits d'histoire de vie qui ont été décrits comme formant un "syndrome polygyne". Dans le chapitre 2, nous démontrons que les colonies à plusieurs reines diffèrent profondément des colonies à une reine en terme de taille, densité de nids, longévité des colonies, poids des nouvelles reines produites ainsi que dans l'allocation entre les individus reproducteurs et les ouvrières. Ces changements multiples dans les traits d'histoire de vie peuvent apporter des bénéfices variés en terme de fitness aux colonies à plusieurs reines. L'augmentation du nombre de reines dans une colonie est généralement associée à une baisse du degré d'agressivité envers les fourmis étrangères au nid. L'hypothèse "phénotype matching" prédit que les colonies à plusieurs reines ont une plus grande diversité dans les facteurs d'origine génétique utilisés pour la reconnaissance, résultant en une capacité diminuée à discriminer une fourmi étrangère au nid. Contrairement à cette hypothèse, nous montrons dans le chapitre 3 que les colonies à une et à plusieurs reines ont des niveaux d'agressivité similaires. De plus, une agressivité accrue est observée entre colonies de structures sociales différentes comparée à des colonies de même structure sociale. Plusieurs hypothèses ont proposé que l'évolution de colonies ä plusieurs reines soit en partie due aux bénéfices résultant d'une augmentation de la diversité génétique dans la colonie. L'hypothèse "task efficiency" prédit que la diversité génétique améliore l'efficacité à effectuer certaines tâches grâce à une expression plus complète et plus souple d'une division du travail génétiquement déterminée. Nous évaluons dans le chapitre 4 si un accroissement de la diversité génétique augmente le polymorphisme de taille des ouvrières, d'où peut ainsi découler une meilleure division du travail. Nous montrons qu'en dépit du fait que la taille des ouvrières soit un caractère héritable, une forte diversité génétique ne se traduit pas par un plus fort polymorphisme chez les ouvrières. Les ouvrières de colonies à plusieurs reines sont plus petites et moins polymorphes que celles des colonies à une seule reine. Dans le chapitre 5, nous démontrons l'existence d'un conflit ouvert entre reines et ouvrières à propos de l'allocation dans les sexes, comme le prédit la théorie de la sélection de parentèle. Nos données révèlent que les reines de F. selysi influencent fortement l'allocation dans les sexes en biaisant la sexe ratio des oeufs. Cependant, certains indices indiquent que les ouvrières éliminent une partie du couvain mâle, ce qui a pour effet d'avoir un investissement dans les sexes au niveau de la population intermédiaire entre les intérêts des reines et des ouvrières.