73 resultados para breeding period
Resumo:
Investigating macro-geographical genetic structures of animal populations is crucial to reconstruct population histories and to identify significant units for conservation. This approach may also provide information about the intraspecific flexibility of social systems. We investigated the history and current structure of a large number of populations in the communally breeding Bechstein's bat (Myotis bechsteinii). Our aim was to understand which factors shape the species' social system over a large ecological and geographical range. Using sequence data from one coding and one noncoding mitochondrial DNA region, we identified the Balkan Peninsula as the main and probably only glacial refugium of the species in Europe. Sequence data also suggest the presence of a cryptic taxon in the Caucasus and Anatolia. In a second step, we used seven autosomal and two mitochondrial microsatellite loci to compare population structures inside and outside of the Balkan glacial refugium. Central European and Balkan populations both were more strongly differentiated for mitochondrial DNA than for nuclear DNA, had higher genetic diversities and lower levels of relatedness at swarming (mating) sites than in maternity (breeding) colonies, and showed more differentiation between colonies than between swarming sites. All these suggest that populations are shaped by strong female philopatry, male dispersal, and outbreeding throughout their European range. We conclude that Bechstein's bats have a stable social system that is independent from the postglacial history and location of the populations. Our findings have implications for the understanding of the benefits of sociality in female Bechstein's bats and for the conservation of this endangered species.
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Some models of sexual selection predict that individuals vary in their genetic quality and reveal some of this variation in their secondary sexual characteristics. Alpine whitefish (Coregonus sp.) develop breeding tubercles shortly before their spawning season. These tubercles are epidermal structures that are distributed regularly along the body sides of both males and females. There is still much unexplained variation in the size of breeding tubercles within both sexes and with much overlap between the sexes. It has been suggested that breeding tubercles function to maintain body contact between the mating partners during spawning, act as weapons for defence of spawning territories, or are sexual signals that reveal aspects of genetic quality. We took two samples of whitefish from their spawning place, one at the beginning and one around the peak of spawning season. We found that females have on average smaller breeding tubercles than males, and that tubercle size partly reveals the stage of gonad maturation. Two independent full-factorial breeding experiments revealed that embryo mortality was significantly influenced by male and female effects. This finding demonstrates that the males differed in their genetic quality (because offspring get nothing but genes from their fathers). Tubercle size was negatively linked to some aspects of embryo mortality in the first breeding experiment but not significantly so in the second. This lack of consistency adds to inconsistent results that were reported before and suggests that (i) some aspects of genetic quality are not revealed in breeding tubercles while others are, or (ii) individuals vary in their signaling strategies and the information content of breeding tubercles is not always reliable. Moreover, the fact that female whitefish have breeding tubercles of significant size while males seem to have few reasons to be choosy suggests that the tubercles might also serve some functions that are not linked to sexual signaling.
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Background: Transplantation improves quality of life (kidney transplantation), and saves lives (heart, lung or liver transplantation), but few qualitative studies have explored existential questionings before transplantation. Methods: In this phenomenological qualitative study, patients registered for kidney (n¼30), liver (n¼11), lung (n¼15), or heart (n¼15) transplantation participated in a semi-structured interview. Findings: The following aspects were discussed: The dilemma of choice, the evaluation process, the endorsement of the ''good candidate's role'', the modification of objects, time and space perception, the co-existence of life and death, and the challenge of the body integrity and of the person's identity. Transplantation generates paradoxical situations, and challenges the person's life values. Discussion: Anxiety and distress may arise with awareness of existential questionings and the co-existence different worlds' life values. Transplantation further generates a broader societal and ethical debate as how to accompany existential questionings in a pragmatic medical environment.
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PPARs are a family of nuclear hormone receptors involved in various processes that could influence ovarian function. We investigated the cellular localization and expression of PPARs during follicular development in ovarian tissue collected from rats 0, 6, 12, 24, and 48 h post-PMSG. A second group of animals received human CG (hCG) 48 h post-PMSG. Their ovaries were removed 0, 4, 8, 12, and 24 h post-hCG to study the periovulatory period. mRNAs corresponding to the PPAR isotypes (alpha, delta, and gamma) were localized by in situ hybridization. Changes in the levels of mRNA for the PPARs were determined by ribonuclease protection assays. PPAR gamma mRNA was localized primarily to granulosa cells, and levels of expression did not change during follicular development. Four hours post-hCG, levels of mRNA for PPAR gamma decreased (P < 0.05) but not uniformly in all follicles. At 24 h post-hCG, levels of PPAR gamma mRNA were reduced 64%, but some follicles maintained high expression. In contrast, mRNAs for PPAR alpha and delta were located primarily in theca and stroma, and their levels did not change during the intervals studied. To investigate the physiologic significance of PPAR gamma in the ovary, granulosa cells from PMSG-primed rats were cultured for 48 h with prostaglandin J(2) (PGJ(2)) and ciglitazone, PPAR gamma activators. Both compounds increased progesterone and E2 secretion (P < 0.05). These data suggest that PPAR gamma is involved in follicular development, has a negative influence on the luteinization of granulosa cells, and/or regulates the periovulatory shift in steroid production. The more general and steady expression of PPARs alpha and delta indicate that they may play a role in basal ovarian function.
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Investigating the mechanisms underlying female mate choice is important for sexual-selection theory, but also for population-genetic studies, because distinctive breeding strategies affect differently the dynamics of gene diversity within populations. Using field-monitoring, genetic-assignment, and laboratory-rearing methods, we investigated chorus attendance, mating success and offspring fitness in a population of lek-breeding tree-frogs (Hyla arborea) to test whether female choice is driven by good genes or complementary genes. Chorus attendance explained approximately 50% of the variance in male mating success, but did not correlate with offspring fitness. By contrast, offspring body mass and growth rate correlated with male attractiveness, measured as the number of matings obtained per night of calling. Genetic similarity between mating partners did not depart from random, and did not affect offspring fitness. We conclude that females are able to choose good partners under natural settings and obtain benefits from the good genes, rather than compatible genes, their offspring inherit. This heritability of fitness is likely to reduce effective population sizes below values previously estimated.
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The history of tax havens is still little known for the decades before World War II. Up to now the studies that have focused on the 1920s and 30s have presented either a very general perspective on the development of tax havens or a narrow national point of view. Based on unpublished historical archives of four countries, this paper offers therefore a new comparative look on international tax competition during this period in order to answer the following question: was the Swiss case - already considered as a quintessential tax haven at the time - specific in comparison to other banking centres? This research has two results. On the one hand, the 1920s and 30s appear as something of a golden age of opportunity for avoiding taxation through the relocation of assets. Actually, most of the financial centres granted consistent tax benefits for imported capital, while the extremely limited degree of international cooperation and the usual guarantee of banking secrecy in European countries prevented the taxation of exported assets. On the other hand, within this general balance sheet, the fiscal strategies of a tax haven like Switzerland differed from those of a great financial power like Great Britain. Whereas the Swiss administration readily placed itself at the service of the bankers, the British policy was more balanced between the contradictory interests of the Board of Inland Revenue, the Treasury and the English business circles.
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In populations of various ant species, many queens reproduce in the same nest (polygyny), and colony boundaries appear to be absent with individuals able to move fi eely between nests (unicoloniality). Such societies depart strongly from a simple family structure and pose a potential challenge to kin selection theory, because high queen number coupled with unrestricted gene flow among nests should result in levels of relatedness among nestmates close to zero. This study investigated the breeding system and genetic structure of a highly polygynous and largely unicolonial population of the wood ant Formica paralugubris. A microsatellite analysis revealed that nestmate workers, reproductive queens and reproductive males (the queens' mates) are all equally related to each other, with relatedness estimates centring around 0.14. This suggests that most of the queens and males reproducing in the study population had mated within or close to their natal nest, and that the queens did not disperse far after mating. We developed a theoretical model to investigate how the breeding system affects the relatedness structure of polygynous colonies. By combining the model and our empirical data, it was estimated that about 99.8% of the reproducing queens and males originated from within the nest, or from a nearby nest. This high rate of local mating and the rarity of long-distance dispersal maintain significant relatedness among nestmates, and contrast with the common view that unicoloniality is coupled with unrestricted gene flow among nests.
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In 10 moderately obese women, 24-h energy expenditure (24EE) was measured in a respiration chamber under four conditions: 1) before weight loss (body weight = 77.9 kg), 2) during weight loss (63.9 kg), 3) after realimentation (62.5 kg), and 4) 6-15 mo after the study diet with ad libitum diet (67.7 kg). The 14 +/- 8 kg (mean +/- SD) weight loss produced a decrease in 24EE of 1498 +/- 1138 kJ/d (P < 0.001), ie, a decrease of weight of 107 kJ.kg body wt-1.d-1. The subsequent 24EE (conditions 3 and 4) remained lower than the value before weight loss. A significant correlation was found between changes before and after weight regain in basal respiratory quotient (RQ) and the spontaneous rate of body-weight gain after cessation of the period of low energy intake (r = 0.89, P < 0.01); this suggests that the value of the postabsorptive RQ may be a predictor of relapse of weight gain. After discontinuation of the low energy diet, an elevated postabsorptive RQ shows that the endogenous lipid oxidation is low, a condition favoring weight gain.
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While adaptive adjustment of sex ratio in the function of colony kin structure and food availability commonly occurs in social Hymenoptera, long-term studies have revealed substantial unexplained between-year variation in sex ratio at the population level. In order to identify factors that contribute to increased between-year variation in population sex ratio, we conducted a comparative analysis across 47 Hymenoptera species differing in their breeding system. We found that between-year variation in population sex ratio steadily increased as one moved from solitary species, to primitively eusocial species, to single-queen eusocial species, to multiple-queen eusocial species. Specifically, between-year variation in population sex ratio was low (6.6% of total possible variation) in solitary species, which is consistent with the view that in solitary species, sex ratio can vary only in response to fluctuations in ecological factors such as food availability. In contrast, we found significantly higher (19.5%) between-year variation in population sex ratio in multiple-queen eusocial species, which supports the view that in these species, sex ratio can also fluctuate in response to temporal changes in social factors such as queen number and queen-worker control over sex ratio, as well as factors influencing caste determination. The simultaneous adjustment of sex ratio in response to temporal fluctuations in ecological and social factors seems to preclude the existence of a single sex ratio optimum. The absence of such an optimum may reflect an additional cost associated with the evolution of complex breeding systems in Hymenoptera societies.
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In Seychelles, cardiovascular diseases (CVD), notably stroke, ischemic heart disease and hypertensive heart disease has become the largest contributor of deaths (40%) in the entire population. CVD also results in a large burden of disability and also has subsequent social and economic impact. The Unit for Prevention and Control of Cardiovascular Diseases (UPCCD) provides leadership, expertise and capacity at national level for the surveillance, prevention and control of cardiovascular diseases through education, programs and input into policy.
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OBJECTIVES: The aim of the present study is to investigate the demographics, aetiologies, complications, treatments and visual outcomes in paediatric uveitis patients in the French-speaking part of Switzerland. METHODS: Chart review of all patients diagnosed with uveitis before the age of 16 years, presenting to two tertiary referral centres (uveitis and paediatric rheumatology clinics) in Lausanne, Switzerland, between 2000 and 2009. RESULTS: Seventy-nine children (37 girls) were identified, 62 living in Switzerland, 15 in Europe and 2 in North Africa. Median age at first symptoms was 9.0 years (range 1.5-15.8 years), with a median follow-up time of 1.8 years (0-8 years). Both eyes were involved in 51 patients (64.6%). The course was acute in 30.4%, chronic in 60.8% and recurrent in 8.9%. Anterior uveitis occurred in 39.2%, intermediate in 32.9%, posterior in 22.8% and panuveitis in 5.1%. The three main diagnoses were idiopathic uveitis (34.2%), JIA-related uveitis (22.8%) and toxoplasmic retinochoroiditis (15.2%). During the last follow-up visit, the visual acuity (VA) was ≥8/10 in 72% of all eyes with a measurable VA. Cataract (8%), ocular hypertension/glaucoma (8%) and macular fibrosis (4%) were the three most common severe complications. Systemic steroids were given to 56% and biological agents to 24% of patients with inflammatory uveitis. CONCLUSIONS: Uveitis in children can be a devastating disease. A strict classification of aetiologies and a tight collaboration between paediatric rheumatologists and ophthalmologists are important to ensure early control of ocular inflammation and improve long-term visual prognosis.
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The integration of the differential equation of the second law of Fick applied to the diffusion of chemical elements in a semi-infinite solid made it easier to estimate the time of stay of olivine mega-cristals in contact with the host lava The results of this research show the existence of two groups of olivine. The first remained in contact with the magmatic liquid during 19 to 22 days, while the second remained so during only 5 to 9 days. This distinction is correlative to that based on the qualitative observation.
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We investigated how territory quality, settlement date and morphometry affected several components of yearly breeding success of a Swiss population of Savi's Warblers Locustella luscinioides. Territories occupied by males differed from unoccupied sites of similar size and location by having higher and denser reeds, a more extensive straw litter, and a thicker cover of dead sedge leaves. Territories with these characteristics were the ones first chosen by males upon spring arrival. These males, however, did not differ in morphometry from those that arrived later. Availability of suitable nesting sites; rather than food availability, appears to be an important choice criterion for territories. Early arriving males had higher breeding success than late males because of a higher mating success and more successful clutches. The positive correlation between male breeding success and territory quality was thus mediated through their common dependence on occupancy date. Female breeding success decreased with the date of first-clutch laying, mainly because late-nesting females fledged fewer broods. Breeding success in either sex did not correlate with morphometry. Our results provide clear support for territory choice by males, but not for mate or territory choice by females, and show the crucial role played by individual settlement date on many aspects of the breeding cycle of both sexes. We propose a lottery model of mate choice. arriving females obtain the best available territories even without choosing mates or territories; since males occupy territories sequentially and in order of decreasing quality, the few unpaired males available at any moment also occupy the best available territories.
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Pseudomonas aeruginosa, une bactérie environnementale ubiquitaire, est un des pathogènes nosocomiaux les plus fréquents aux soins intensifs. La source de ce microorganisme peut être soit endogène, 2,6 à 24 % des patients hospitalisés étant colonisés au niveau digestif, soit exogène. La proportion des cas d'infections à P. aeruginosa d'origine exogène, donc secondaires à une transmission par manuportage ou par l'eau du réseau utilisée pour la toilette ou d'autres soins, reste débattue. Or une meilleure évaluation du taux d'infections exogènes est importante pour la mise en place de mesures de contrôle appropriées. Le but de cette étude était de déterminer sur une période de 10 ans les rôles respectifs des sources exogènes (robinets, autres patients) et endogène dans la colonisation et/ou l'infection par P.aeruginosa chez les patients des Soins Intensifs, ainsi que de documenter les variations épidémiologiques au cours du temps. L'étude a été menée dans les unités de Soins Intensifs du Centre Hospitalier Universitaire Vaudois (CHUV). Les patients colonisés et/ou infectés par P. aeruginosa entre 1998 et 2007ont été identifiés via la base de données du laboratoire de microbiologie. Ils ont été inclus dans l'étude s'ils étaient hospitalisés dans une des unités de Soins Intensifs, Durant cette période, des prélèvements pour recherche de P. aeruginosa ont été effectués sur des robinets des soins intensifs. Un typage moléculaire a été effectué sur toutes les souches cliniques et environnementales isolées en 1998, 2000, 2003, 2004 et 2007. Les patients inclus dans l'étude ont été répartis en quatre catégories (A-D) selon le résultat du typage moléculaire leur souche de P. aeruginosa. La catégorie A inclut les cas pour lesquels le génotype de P. aeruginosa est identique à un des génotypes retrouvé dans l'environnement. La catégorie B comprend les cas pour lesquels le génotype est identique à celui d'au moins un autre patient. La catégorie C comprend les cas avec un génotype unique et la catégorie D comprend les cas pour lesquels la souche était non disponible pour le typage. Les cas des catégories A et B sont considérés comme ayant une origine exogène. Au cours des années de l'étude, le nombre d'admissions aux soins intensifs est resté stable. En moyenne, 86 patients par année ont été identifiés colonisés ou infectés par P. aeruginosa aux Soins Intensifs. Durant la première année d'investigation, un grand nombre de patients colonisés par une souche de P. aeruginosa identique à une de celles retrouvées dans l'environnement a été mis en évidence. Par la suite, possiblement suite à l'augmentation de la température du réseau d'eau chaude, le nombre de cas dans la catégorie A a diminué. Dans la catégorie B, le nombre de cas varie de 1,9 à 20 cas/1000 admissions selon les années. Ce nombre est supérieur à 10 cas/1000 admissions en 1998, 2003 et 2007 et correspond à des situations épidémiques transitoires. Tout au long des 10 ans de l'étude, le nombre de cas dans la catégorie C (source endogène) est demeuré stable et indépendant des variations du nombre de cas dans les catégories A et B. En conclusion, la contribution relative des réservoirs endogène et exogène dans la colonisation et/ou l'infection des patients de soins Intensifs varie au cours du temps. Les facteurs principaux qui contribuent à de telles variations sont probablement le degré de contamination de l'environnement, la compliance des soignants aux mesures de contrôle des infections et la génétique du pathogène lui-même. Etant donné que ce germe est ubiquitaire dans l'environnement aqueux et colonise jusqu'à 15% des patients hospitalisés, la disparition de son réservoir endogène semble difficile. Cependant, cette étude démontre que son contrôle est possible dans l'environnement, notamment dans les robinets en augmentant la température de l'eau. De plus, si une souche multi-résistante est retrouvée de manière répétée dans l'environnement, des efforts doivent être mis en place pour éliminer cette souche. Des efforts doivent être également entrepris afin de limiter la transmission entre les patients, qui est une cause importante et récurrente de contamination exogène. - Pseudomonas aeruginosa is one of the leading nosocomial pathogens in intensive care units (ICUs). The source of this microorganism can be either endogenous or exogenous. The proportion of cases as a result of transmission is still debated, and its elucidation is important for implementing appropriate control measures. To understand the relative importance of exogenous vs. endogenous sources of P. aeru¬ginosa, molecular typing was performed on all available P. aeruginosa isolated from ICU clinical and environmental specimens in 1998, 2000, 2003, 2004 and 2007. Patient samples were classified according to their P. aeruginosa genotypes into three categories: (A) identical to isolate from faucet; (B) identical to at least one other patient sample and not found in faucet; and (C) unique genotype. Cases in cat¬egories A and Β were considered as possibly exogenous, and cases in category C as possibly endogenous. A mean of 34 cases per 1000 admissions per year were found to be colonized or infected by P. aeruginosa. Higher levels of faucet contamination were correlated with a higher number of cases in category A. The number of cases in category Β varied from 1.9 to 20 cases per 1000 admissions. This num¬ber exceeded 10/1000 admissions on three occasions and was correlated with an outbreak on one occasion. The number of cases con¬sidered as endogenous (category C) was stable and independent of the number of cases in categories A and B. The present study shows that repeated molecular typing can help identify variations in the epidemiology of P. aeruginosa in ICU patients and guide infection control measures.