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

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.

Development of Implantable Flow-Through Left Ventricular Pressure Telemetric Transmitter for small Rodent Animals

Objective: Although 24-hour arterial blood pressure can be monitored in a free-moving animal using pressure telemetric transmitter mostly from Data Science International (DSI), accurate monitoring of 24-hour mouse left ventricular pressure (LVP) is not available because of its insufficient frequency response to a high frequency signal such as the maximum derivative of mouse LVP (LVdP/dtmax and LVdP/dtmin). The aim of the study was to develop a tiny implantable flow-through LVP telemetric transmitter for small rodent animals, which can be potentially adapted for human 24 hour BP and LVP accurate monitoring. Design and Method: The mouse LVP telemetric transmitter (Diameter: _12 mm, _0.4 g) was assembled by a pressure sensor, a passive RF telemetry chip, and to a 1.2F Polyurethane (PU) catheter tip. The device was developed in two configurations and compared with existing DSI system: (a) prototype-I: a new flow-through pressure sensor with wire link and (b) prototype-II: prototype-I plus a telemetry chip and its receiver. All the devices were applied in C57BL/6J mice. Data are mean_SEM. Results: A high frequency response (>100 Hz) PU heparin saline-filled catheter was inserted into mouse left ventricle via right carotid artery and implanted, LV systolic pressure (LVSP), LVdP/dtmax, and LVdP/dtmin were recorded on day2, 3, 4, 5, and 7 in conscious mice. The hemodynamic values were consistent and comparable (139_4 mmHg, 16634_319, - 12283_184 mmHg/s, n¼5) to one recorded by a validated Pebax03 catheter (138_2mmHg, 16045_443 and -12112_357 mmHg/s, n¼9). Similar LV hemodynamic values were obtained with Prototype-I. The same LVP waveforms were synchronically recorded by Notocord wire and Senimed wireless software through prototype-II in anesthetized mice. Conclusion: An implantable flow-through LVP transmitter (prototype-I) is generated for LVP accurate assessment in conscious mice. The prototype-II needs a further improvement on data transmission bandwidth and signal coupling distance to its receiver for accurate monitoring of LVP in a freemoving mouse.

Domestic radon exposure and risk of childhood cancer: a prospective census-based cohort study

BACKGROUND: In contrast with established evidence linking high doses of ionizing radiation with childhood cancer, research on low-dose ionizing radiation and childhood cancer has produced inconsistent results. OBJECTIVE: We investigated the association between domestic radon exposure and childhood cancers, particularly leukemia and central nervous system (CNS) tumors. METHODS: We conducted a nationwide census-based cohort study including all children < 16 years of age living in Switzerland on 5 December 2000, the date of the 2000 census. Follow-up lasted until the date of diagnosis, death, emigration, a child's 16th birthday, or 31 December 2008. Domestic radon levels were estimated for each individual home address using a model developed and validated based on approximately 45,000 measurements taken throughout Switzerland. Data were analyzed with Cox proportional hazard models adjusted for child age, child sex, birth order, parents' socioeconomic status, environmental gamma radiation, and period effects. RESULTS: In total, 997 childhood cancer cases were included in the study. Compared with children exposed to a radon concentration below the median (< 77.7 Bq/m3), adjusted hazard ratios for children with exposure ≥ the 90th percentile (≥ 139.9 Bq/m3) were 0.93 (95% CI: 0.74, 1.16) for all cancers, 0.95 (95% CI: 0.63, 1.43) for all leukemias, 0.90 (95% CI: 0.56, 1.43) for acute lymphoblastic leukemia, and 1.05 (95% CI: 0.68, 1.61) for CNS tumors. CONCLUSIONS: We did not find evidence that domestic radon exposure is associated with childhood cancer, despite relatively high radon levels in Switzerland.

The biogeography of mitochondrial and nuclear discordance in animals.

Combining nuclear (nuDNA) and mitochondrial DNA (mtDNA) markers has improved the power of molecular data to test phylogenetic and phylogeographic hypotheses and has highlighted the limitations of studies using only mtDNA markers. In fact, in the past decade, many conflicting geographic patterns between mitochondrial and nuclear genetic markers have been identified (i.e. mito-nuclear discordance). Our goals in this synthesis are to: (i) review known cases of mito-nuclear discordance in animal systems, (ii) to summarize the biogeographic patterns in each instance and (iii) to identify common drivers of discordance in various groups. In total, we identified 126 cases in animal systems with strong evidence of discordance between the biogeographic patterns obtained from mitochondrial DNA and those observed in the nuclear genome. In most cases, these patterns are attributed to adaptive introgression of mtDNA, demographic disparities and sex-biased asymmetries, with some studies also implicating hybrid zone movement, human introductions and Wolbachia infection in insects. We also discuss situations where divergent mtDNA clades seem to have arisen in the absence of geographic isolation. For those cases where foreign mtDNA haplotypes are found deep within the range of a second taxon, data suggest that those mtDNA haplotypes are more likely to be at a high frequency and are commonly driven by sex-biased asymmetries and/or adaptive introgression. In addition, we discuss the problems with inferring the processes causing discordance from biogeographic patterns that are common in many studies. In many cases, authors presented more than one explanation for discordant patterns in a given system, which indicates that likely more data are required. Ideally, to resolve this issue, we see important future work shifting focus from documenting the prevalence of mito-nuclear discordance towards testing hypotheses regarding the drivers of discordance. Indeed, there is great potential for certain cases of mitochondrial introgression to become important natural systems within which to test the effect of different mitochondrial genotypes on whole-animal phenotypes.

Exposition de l'enfant a des violences domestiques. Un modèle pluridisciplinaire de détection, d'evaluation et de prise en charge [Children's exposure to domestic violence. A multidisciplinary model of detection, assessment and management].

Children psychological abuse is difficult to identify. However, its consequences on child development can be as serious as physical and sexual abuses. It is therefore essential, to implement in our hospitals, structures whose missions are successively to detect victims, evaluate them on somatic and psychological levels, and elaborate a therapy. We propose a model for the achievement of these objectives through collaboration between the Medical Unit of Violence, the Pediatric CAN Team and the Unit of Les Boréales.

Amoeba-resisting Chlamydiales present in domestic drinking water and their potential role in pneumonia

Chlamydia-related bacteria classified in the Chlamydiales order, are strictly intracellular bacteria and are able for the most to replicate in free-living amoebae. Amoebae, ubiquitous in the environment and especially in water, are very resistant to disinfection used in drinking water production. Thus, amoebae may reach easily the distribution and domestic water system, potentially sheltering amoeba-resisting bacteria including Legionella, mycobacteria and Chlamydiales. Indeed, some of these amoeba-resisting bacteria have been shown to cause respiratory infections in people inhaling contaminated water. Therefore, an environmental and clinical study was conducted to determine if Chlamydiales bacteria are also involved in respiratory infections and if a transmission through domestic drinking water could occur. First, large scale molecular and serological tools specific of Chlamydia-related bacteria were developed and then were applied on clinical samples from patients with and without pneumonia. Simultaneously, water and biofilm samples from households of the same patients were investigated using molecular and culture methods for the presence of Chlamydiales bacteria. Chlamydiales were detected in the nasopharyngeal flora from patients with and without pneumonia. However, no significant difference was observed between both groups. Conversely, serological investigations showed that antibody reactivity against members of the Criblamydiaceae was associated with pneumonia. The thesis provided very efficient tools that showed the presence of Chlamydiales in human nasopharyngeal flora as well as in the majority of the domestic drinking water. However, no transmission from domestic drinking water to human could be demonstrated. These tools will help in the future specifying the ecology and pathogenicity of the Chlamydia-re\ated bacteria and especially of the species belonging to the Criblamydiaceae family.

The role of migration and domestic transmission in the spread of HIV-1 non-B subtypes in Switzerland.

BACKGROUND: By analyzing human immunodeficiency virus type 1 (HIV-1) pol sequences from the Swiss HIV Cohort Study (SHCS), we explored whether the prevalence of non-B subtypes reflects domestic transmission or migration patterns. METHODS: Swiss non-B sequences and sequences collected abroad were pooled to construct maximum likelihood trees, which were analyzed for Swiss-specific subepidemics, (subtrees including ≥80% Swiss sequences, bootstrap >70%; macroscale analysis) or evidence for domestic transmission (sequence pairs with genetic distance <1.5%, bootstrap ≥98%; microscale analysis). RESULTS: Of 8287 SHCS participants, 1732 (21%) were infected with non-B subtypes, of which A (n = 328), C (n = 272), CRF01_AE (n = 258), and CRF02_AG (n = 285) were studied further. The macroscale analysis revealed that 21% (A), 16% (C), 24% (CRF01_AE), and 28% (CRF02_AG) belonged to Swiss-specific subepidemics. The microscale analysis identified 26 possible transmission pairs: 3 (12%) including only homosexual Swiss men of white ethnicity; 3 (12%) including homosexual white men from Switzerland and partners from foreign countries; and 10 (38%) involving heterosexual white Swiss men and females of different nationality and predominantly nonwhite ethnicity. CONCLUSIONS: Of all non-B infections diagnosed in Switzerland, <25% could be prevented by domestic interventions. Awareness should be raised among immigrants and Swiss individuals with partners from high prevalence countries to contain the spread of non-B subtypes.

What animals can teach clinicians about the hippocampus

Abnormalities in hippocampal structure and function have been reported in a number of human neuropathological and neurodevelopmental disorders, including Alzheimer's disease, autism spectrum disorders, Down syndrome, epilepsy, and schizophrenia. Given the complexity of these disorders, animal studies are invaluable and remain to date irreplaceable, providing fundamental knowledge regarding the basic mechanisms underlying normal and pathological human brain structure and function. However, there is a prominent ill-conceived view in current research that scientists should be restricted to using animal models of human diseases that can lead to results applicable to humans within a few years. Although there is no doubt that translational studies of this kind are important and necessary, limiting animal studies to applicable questions is counterproductive and will ultimately lead to a lack of knowledge and an inability to address human health problems. Here, we discuss findings regarding the normal postnatal development of the monkey hippocampal formation, which provide an essential framework to consider the etiologies of different neuropathological disorders affecting human hippocampal structure and function. We focus on studies of gene expression in distinct hippocampal regions that shed light on some basic mechanisms that might contribute to the etiology of schizophrenia. We argue that researchers, as well as clinicians, should not consider the use of animals in research only as 'animal models' of human diseases, as they will continue to need and benefit from a better understanding of the normal structure and functions of the hippocampus in 'model animals'.