Estimation of Genetic Divergence and Gene Flow between Culex pipiens and Culex quinquefasciatus (Diptera: Culicidae) in Argentina

Allele frequencies at seven polymorphic loci controlling the synthesis of enzymes were analyzed in six populations of Culex pipiens L. and Cx. quinquefasciatus Say. Sampling sites were situated along a north-south line of about 2,000 km in Argentina. The predominant alleles at Mdh, Idh, Gpdh and Gpi loci presented similar frequencies in all the samples. Frequencies at the Pgm locus were similar for populations pairs sharing the same geographic area. The loci Cat and Hk-1 presented significant geographic variation. The latter showed a marked latitudinal cline, with a frequency for allele b ranging from 0.99 in the northernmost point to 0.04 in the southernmost one, a pattern that may be explained by natural selection (FST = 0.46; p < 0.0001) on heat sensitive alleles. The average value of FST (0.088) and Nm (61.12) indicated a high gene flow between adjacent populations. A high correlation was found between genetic and geographic distance (r = 0.83; p < 0.001). The highest genetic identity (IN = 0.988) corresponded to the geographically closest samples from the central area. In one of these localities Cx. quinquefasciatus was predominant and hybrid individuals were detected, while in the other, almost all the specimens were identified as Cx. pipiens. To verify the fertility between Cx. pipiens and Cx. quinquefasciatus from the northern- and southernmost populations, experimental crosses were performed. Viable egg rafts were obtained from both reciprocal crosses. Hatching ranged from 76.5 to 100%. The hybrid progenies were fertile through two subsequent generations

THE USE OF SIMULATIONS IN EVOLUTIONARY POPULATION GENETICS: APPLICATIONS ON HUMANS, OWLS AND VIRTUAL ORGANISMS

Summary (in English) Computer simulations provide a practical way to address scientific questions that would be otherwise intractable. In evolutionary biology, and in population genetics in particular, the investigation of evolutionary processes frequently involves the implementation of complex models, making simulations a particularly valuable tool in the area. In this thesis work, I explored three questions involving the geographical range expansion of populations, taking advantage of spatially explicit simulations coupled with approximate Bayesian computation. First, the neutral evolutionary history of the human spread around the world was investigated, leading to a surprisingly simple model: A straightforward diffusion process of migrations from east Africa throughout a world map with homogeneous landmasses replicated to very large extent the complex patterns observed in real human populations, suggesting a more continuous (as opposed to structured) view of the distribution of modern human genetic diversity, which may play a better role as a base model for further studies. Second, the postglacial evolution of the European barn owl, with the formation of a remarkable coat-color cline, was inspected with two rounds of simulations: (i) determine the demographic background history and (ii) test the probability of a phenotypic cline, like the one observed in the natural populations, to appear without natural selection. We verified that the modern barn owl population originated from a single Iberian refugium and that they formed their color cline, not due to neutral evolution, but with the necessary participation of selection. The third and last part of this thesis refers to a simulation-only study inspired by the barn owl case above. In this chapter, we showed that selection is, indeed, effective during range expansions and that it leaves a distinguished signature, which can then be used to detect and measure natural selection in range-expanding populations. Résumé (en français) Les simulations fournissent un moyen pratique pour répondre à des questions scientifiques qui seraient inabordable autrement. En génétique des populations, l'étude des processus évolutifs implique souvent la mise en oeuvre de modèles complexes, et les simulations sont un outil particulièrement précieux dans ce domaine. Dans cette thèse, j'ai exploré trois questions en utilisant des simulations spatialement explicites dans un cadre de calculs Bayésiens approximés (approximate Bayesian computation : ABC). Tout d'abord, l'histoire de la colonisation humaine mondiale et de l'évolution de parties neutres du génome a été étudiée grâce à un modèle étonnement simple. Un processus de diffusion des migrants de l'Afrique orientale à travers un monde avec des masses terrestres homogènes a reproduit, dans une très large mesure, les signatures génétiques complexes observées dans les populations humaines réelles. Un tel modèle continu (opposé à un modèle structuré en populations) pourrait être très utile comme modèle de base dans l'étude de génétique humaine à l'avenir. Deuxièmement, l'évolution postglaciaire d'un gradient de couleur chez l'Effraie des clocher (Tyto alba) Européenne, a été examiné avec deux séries de simulations pour : (i) déterminer l'histoire démographique de base et (ii) tester la probabilité qu'un gradient phénotypique, tel qu'observé dans les populations naturelles puisse apparaître sans sélection naturelle. Nous avons montré que la population actuelle des chouettes est sortie d'un unique refuge ibérique et que le gradient de couleur ne peux pas s'être formé de manière neutre (sans l'action de la sélection naturelle). La troisième partie de cette thèse se réfère à une étude par simulations inspirée par l'étude de l'Effraie. Dans ce dernier chapitre, nous avons montré que la sélection est, en effet, aussi efficace dans les cas d'expansion d'aire de distribution et qu'elle laisse une signature unique, qui peut être utilisée pour la détecter et estimer sa force.

Mothers' and Fathers' Early Relationship With Their Infant: Similar Yet Temporally Discordant Themes [La relation initiale des parents avec leur nourrisson: Thèmes similaires quoique temporellement discordants]

Objective: To examine first-time mothers' and fathers' themes in their relationship with their infant, how these themes change during the first four months postpartum, and similarities and differences in mothers' and fathers' themes. Participants: Eighteen first-time mother-father couples were separately interviewed at one; six and 16 weeks postpartum. Data Analysis: Audio-taped, transcribed interviews were analysed using a Grounded Theory approach. Results: Our findings reveal a common set of themes for mothers and fathers in relation to the infant : 1: Discovery, 2: Physical Proximity, 3: Emotional Closeness, 4: Initiation of Complementary Interactions and 5: Commitment to Love and Care. However, there was a striking lack of concordance between mothers and fathers for these themes at each point in time. Conclusions: Mothers' and fathers' experience of the early relationship with their infant is unique. Focussing on maternal as well as paternal ways of experiencing the early relationship with their infant sets the way to understanding early developing relationships in the family context.

AIDS prevention: consensus and dissension regarding the meaning

Aim: In Western Europe, HIV/AIDS prevention has been based on the provision of information intended to lead the public to voluntarily adapt their behaviour so as to avoid the risk of virus transmission. Whether conveyed in a written or oral form, the messages of prevention are essentially verbal. Sociolinguistic research confirms that, even within a given culture, the meaning attributed to lexical items varies. It was hypothesised that understandings of the terms used in HIV/AIDS prevention in French-speaking Switzerland would vary, and research was undertaken to identify the level and nature of this variation both between and among those who transmit (prevention providers) and those who receive (the public) the messages. Method/issue: All HIV/AIDS prevention material available in French-speaking Switzerland in 2004 was assembled and a corpus of 50 key documents identified. Two series of lexical items were generated from this corpus: one composed of technical terms potentially difficult to understand, and the other, of terms used in everyday language with implicit, and therefore potentially variable, meaning. The two lists of terms were investigated in qualitative interviews in stratified purposive samples of the general public (n=60) and prevention providers (n=30), using standard socio-linguistic methodology. A further quantitative study (CATI) in the general population (17 - 49 yrs.; n=500) investigated understandings of 15 key prevention terms found in the qualitative research to have been associated with high levels of dissension. Results/comments: Selected aspects of the results will be presented. In illustration: meanings attributed to the different terms in both the public and the providers varied. For example, when a relationship is described as "stable", this may be understood as implying exclusive sexual relations or long duration, with an interaction between the two traits; the term "sexual intercourse" may or may not be used to refer to oral sex; "making love" may or may not necessarily include an act of penetration; the pre-ejaculate is qualified by some as sperm, and by others not... Understanding of frequently used "technical" terms in prevention was far from universal; for example, around only a half of respondents understood the meaning of "safer sex". Degree of understanding of these terms was linked to education, whereas variability in meaning in everyday language was not linked to socio-economic variables. Discussion: Findings indicate the need for more awareness regarding the heterogeneity of meaning around the terms regularly used in prevention. Greater attention should be paid to the formulation of prevention messages, and providers should take precautions to ensure that the meanings they wish to convey are those perceived by the receivers of their messages. Wherever possible, terms used should be defined and meanings rendered explicit.

Revue des hospitalisations du Service de chirurgie générale du CHUV en 1997

[Table des matières] 1. Matériel et méthode. 1.1. Protocole princeps. 1.2. Protocole adapté. 1.3. Analyse des causes de délai. 2. Résultats : exhaustivité de la cueillette de données. 3. Discussion et conclusions. 4. Annexes : 1. Soins requis (PNR). 2. Formulaire de saisie. 3. Responsabilités des délais. 4. Distribution des critères. 5. Cause de délai.

The significance of pre-existing minority Y181C mutations on virological failure of NNRTI-based, first-line antiretroviral therapy

Background: Reduced re'nal function has been reported with tenofovir disoproxil fumarate (TDF). It is not clear whether TDF co-administered with a boosted protease inhibitor (PI) leads to a greater decline in renal function than TDF co-administered with a non-nucleoside reverse transcriptase inhibitor (NNRTI).Methods: We selected ail antiretroviral therapy-naive patients in the Swiss HIV Cohort Study (SHCS) with calibrated or corrected serum creatinine measurements starting antiretroviral therapy with TDF and either efavirenz (EFV) or the ritonavir-boosted PIs, lopinavir (LPV/r) or atazanavir (ATV/r). As a measure of renal function, we used the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation to estimate the glomerular filtration rate (eGFR). We calculated the difference in eGFR over time between two therapies using a marginal model for repeated measures. In weighted analyses, observations were weighted by the product of their point of treatment and censoring weights to adjust for differences both in the sort of patients starting each therapy and in the sort of patients remaining on each therapy over time.Results: By March 2011, 940 patients with at least one creatinine measurement on a first therapy with either TDF and EFV (n=484), TDF and LPVlr (n=269) or TDF and ATV/r (n=187) had been followed for a median of 1. 7, 1.2 and 1.3 years, respectively. Table 1 shows the difference in average estimated GFR (eGFR) over time since starting cART for two marginal models. The first model was not adjusted for potential confounders; the second mode! used weights to adjust for confounders. The results suggest a greater decline in renal function during the first 6 months if TDF is used with a PI rather than with an NNRTI, but no further difference between these therapies after the first 6 months. TDF and ATV/r may lead to a greater decline in the first 6 months than TDF and LPVlr.Conclusions: TDF co-administered with a boosted PI leads to a greater de cline in renal function over the first 6 months of therapy than TDF co-administered with an NNRTI; this decline may be worse with ATV/r than with LPV/r.

Towards an understanding of the epigenetics of schistosomes: a comparative epigenomic study

As in perhaps all eukaryotes, schistosomes use a supplementary information transmitting system, the epigenetic inheritance system, to shape genetic information and to produce different phenotypes. In contrast to other important parasites, the study of epigenetic phenomena in schistosomes is still in its infancy. Nevertheless, we are beginning to grasp what goes on behind the epigenetic scene in this parasite. We have developed techniques of native chromatin immunoprecipitation (N-ChIP) and associated the necessary bioinformatics tools that allow us to run genome-wide comparative chromatin studies on Schistosoma mansoni at different stages of its life cycle, on different strains and on different sexes. We present here an application of such an approach to study the genetic and epigenetic basis for a phenotypic trait, the compatibility of S. mansoni with its invertebrate host Biomphalaria glabrata. We have applied the ChIP procedure to two strains that are either compatible or incompatible with their intermediate host. The precipitated DNA was sequenced and aligned to a reference genome and this information was used to determine regions in which both strands differ in their genomic sequence and/or chromatin structure. This procedure allowed us to identify candidate genes that display either genetic or epigenetic difference between the two strains.