Hybridization and speciation.

Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near-instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky-Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock-on effects on speciation both within and outside regions of hybridization.

Long-term effects of ACTH combined with angiotensin II on steroidogenesis and adrenal zona glomerulosa morphology in the rat.

To test the hypothesis that the trophic action of angiotensin II on the adrenal zona glomerulosa may allow a sustained stimulation of aldosterone by ACTH by preventing the morphological changes of the zona glomerulosa cells into zona fasciculata-like elements we investigated the effects in rats of a 6-day treatment with ACTH (100 micrograms/kg/day) alone or combined with angiotensin II (300 ng/kg/day) on corticosterone and aldosterone production and adrenal morphology. The responsiveness of both steroids to an acute ACTH dose was also studied on the last day of long-term treatment. Morphologic data showed that prolonged ACTH treatment stimulated the growth of zona glomerulosa cells, though it transformed the tubulo-lamellar cristae of mitochondria into a homogeneous population of vesicles. Angiotensin II furthered the trophic effects of ACTH but prevented the mitochondrial transformation. Despite its ability to conserve the well differentiated aspect of the zona glomerulosa cells, the administration of angiotensin II was unable to prevent the fall in the secretion of aldosterone caused by chronic ACTH treatment and its subsequent unresponsiveness to ACTH stimulation.

Myocardial infarct size and mortality depend on the time of day-a large multicenter study.

BACKGROUND: Different studies have shown circadian variation of ischemic burden among patients with ST-Elevation Myocardial Infarction (STEMI), but with controversial results. The aim of this study was to analyze circadian variation of myocardial infarction size and in-hospital mortality in a large multicenter registry. METHODS: This retrospective, registry-based study was based on data from AMIS Plus, a large multicenter Swiss registry of patients who suffered myocardial infarction between 1999 and 2013. Peak creatine kinase (CK) was used as a proxy measure for myocardial infarction size. Associations between peak CK, in-hospital mortality, and the time of day at symptom onset were modelled using polynomial-harmonic regression methods. RESULTS: 6,223 STEMI patients were admitted to 82 acute-care hospitals in Switzerland and treated with primary angioplasty within six hours of symptom onset. Only the 24-hour harmonic was significantly associated with peak CK (p = 0.0001). The maximum average peak CK value (2,315 U/L) was for patients with symptom onset at 23:00, whereas the minimum average (2,017 U/L) was for onset at 11:00. The amplitude of variation was 298 U/L. In addition, no correlation was observed between ischemic time and circadian peak CK variation. Of the 6,223 patients, 223 (3.58%) died during index hospitalization. Remarkably, only the 24-hour harmonic was significantly associated with in-hospital mortality. The risk of death from STEMI was highest for patients with symptom onset at 00:00 and lowest for those with onset at 12:00. DISCUSSION: As a part of this first large study of STEMI patients treated with primary angioplasty in Swiss hospitals, investigations confirmed a circadian pattern to both peak CK and in-hospital mortality which were independent of total ischemic time. Accordingly, this study proposes that symptom onset time be incorporated as a prognosis factor in patients with myocardial infarction.

Diagnostic de la maladie coronarienne stable par FFR non invasive, mythe ou réalité [Diagnosis of stable coronary artery disease with non-invasive FFR: myth or reality?].

Decision to revascularize a patient with stable coronary artery disease should be based on the detection of myocardial ischemia. If this decision can be straightforward with significant stenosis or in non-significant stenosis, the decision with intermediate stenosis is far more difficult and require invasive measures of functional impact of coronary stenosis on maximal blood (flow fractional flow reserve=FFR). A recent computer based method has been developed and is able to measure FFR with data acquired during a standard coronary CT-scan (FFRcT). Two recent clinical studies (DeFACTO and DISCOVER-FLOW) show that diagnostic performance of FFRcT was associated with improved diagnostic accuracy versus standard coronary CT-scan for the detection of myocardial ischemia although FFRcT need further development.

Developmental time of immature forms of Sabethes aurescens Lutz (Diptera, Culicidae) from artificially perforated bamboo in the rain forest of southern Brazil

The development time of the immature forms of Sabethes aurescens Lutz, 1905, from perforated bamboo in the southern Brazil rain forest was studied under laboratory conditions. Mean development periods were 5±2.23, 10±5.20, 14±8.26, 36±13.90 and 9±2.43 days, respectively, for the four larval instars and pupae. The 4th instar of females was longer than that of males. Implications of the long development time of the immature forms of Sa. aurescens are discussed.

Temporal distribution of Aedes aegypti Linnaeus (Diptera, Culicidae), in a Hospital in Cuiabá, State of Mato Grosso, Brazil

This study aimed at registering and monitoring the presence of Aedes aegypti in the University Hospital Júlio Muller, Cuiabá-MT, as well as investigating the influence of temperature and rainfall on its temporal distribution and egg densities in ovitraps. The study was performed from April/2007 to March/2008, utilizing ovitraps with 10% of hay infusion and a wood paddle as an oviposition substrate. For surveillance, one ovitrap was placed in each of the 12 points distributed throughout the hospital. Ovitraps were collected monthly at the end of a 5-day installation period. After egg counting, wood paddles were immersed in water to allow larval eclosion for species identification through optical microscopy. Egg Density Index (EDI), Positive Ovitraps Index (POI), and Mean Number of Eggs (MNE) were used for data analysis. The presence of A. aegypti in the hospital was registered throughout the study period, except in July. The MNE was proportionally higher in the internal area (n= 8.47 eggs/paddle) when compared to the external area (n= 5.46 eggs/paddle), and was higher in September/October 2007 and January/February 2008. A significant increase in EDI, POI and MNE was registered in periods where the average temperature was higher, and the increase in POI was also concomitant with an increase in rainfall. The continuous presence of A. aegypti in the hospital throughout the study period, points out the need of including this mosquito in the arthropod control list in this environment. This is particularly important, considering that A. aegypti is an important vector of several arboviroses.

Krypton laser photocoagulation induces retinal vascular remodeling rather than choroidal neovascularization.

The purpose of this study is to analyze the retina and choroid response following krypton laser photocoagulation. Ninety-two C57BL6/Sev129 and 32 C57BL/6J, 5-6-week-old mice received one single krypton (630 nm) laser lesion: 50 microm, 0.05 s, 400 mW. On the following day, every day thereafter for 1 week and every 2-3 days for the following 3 weeks, serial sections throughout the lesion were systematically collected and studied. Immunohistology using specific markers or antibodies for glial fibrillary acidic protein (GFAP) (astrocytes, glia and Muller's cells), von Willebrand (vW) (vascular endothelial cells), TUNEL (cells undergoing caspase dependent apoptosis), PCNA (proliferating cell nuclear antigen) p36, CD4 and F4/80 (infiltrating inflammatory and T cells), DAPI (cell nuclei) and routine histology were carried out. Laser confocal microscopy was also performed on flat mounts. Temporal and spatial observations of the created photocoagulation lesions demonstrate that, after a few hours, activated glial cells within the retinal path of the laser beam express GFAP. After 48 h, GFAP-positive staining was also detected within the choroid lesion center. "Movement" of this GFAP-positive expression towards the lasered choroid was preceded by a well-demarcated and localized apoptosis of the retina outer nuclear layer cells within the laser beam path. Later, death of retinal outer nuclear cells and layer thinning at this site was followed by evagination of the inner nuclear retinal layer. Funneling of the entire inner nuclear and the thinned outer nuclear layers into the choroid lesion center was accompanied by "dragging" of the retinal capillaries. Thus, from days 10 to 14 after krypton laser photocoagulation onward, well-formed blood capillaries (of retinal origin) were observed within the lesion. Only a few of the vW-positive capillary endothelial cells stained also for PCNA p36. In the choroid, dilatation of the vascular bed occurred at the vicinity of the photocoagulation site and around it. Confocal microscopy demonstrates that the vessels throughout the path lesion are located within the neuroretina while in the choroid (after separation of the neural retina) only GFAP-positive but no lectin-positive cells can be seen. The involvement of infiltrating inflammatory cells in these remodeling and healing processes remained minimal throughout the study period. During the 4 weeks following krypton laser photocoagulation in the mouse eye, processes of wound healing and remodeling appear to be driven by cells (and vessels) originating from the retina.

Renal tissue oxygenation in essential hypertension and chronic kidney disease.

Animal studies suggest that renal tissue hypoxia plays an important role in the development of renal damage in hypertension and renal diseases, yet human data were scarce due to the lack of noninvasive methods. Over the last decade, blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI), detecting deoxyhemoglobin in hypoxic renal tissue, has become a powerful tool to assess kidney oxygenation noninvasively in humans. This paper provides an overview of BOLD-MRI studies performed in patients suffering from essential hypertension or chronic kidney disease (CKD). In line with animal studies, acute changes in cortical and medullary oxygenation have been observed after the administration of medication (furosemide, blockers of the renin-angiotensin system) or alterations in sodium intake in these patient groups, underlining the important role of renal sodium handling in kidney oxygenation. In contrast, no BOLD-MRI studies have convincingly demonstrated that renal oxygenation is chronically reduced in essential hypertension or in CKD or chronically altered after long-term medication intake. More studies are required to clarify this discrepancy and to further unravel the role of renal oxygenation in the development and progression of essential hypertension and CKD in humans.

Retinal degeneration progression changes lentiviral vector cell targeting in the retina

Ce travail de thèse a été réalisé au sein de l'Unité de Thérapie Génique et Biologie des Cellules Souches de l'Hôpital Jules- Gonin dans le Service d'Ophtalmologie de l'Université de Lausanne. Ce laboratoire recherche des solutions thérapeutiques pour des maladies dégénératives et incurables de la rétine comme les rétinites pigmentaires (RP). Ayant déjà montré certains résultats dans le domaine, la thérapie génique a été notre outil pour ce travail. Cette méthode se base sur le principe de remplacer un gène déficient par sa copie normale, en transportant celle-ci au coeur même du noyau par un vecteur. Il existe à l'heure actuelle différents vecteurs. Un des plus efficaces est un vecteur viral non-réplicatif : le lentivirus, dérivé de HIV-1. Celui-ci a la capacité d'intégrer le génome de la cellule cible, lui conférant ainsi un nouveau matériel génétique. Notre but a été d'établir le tropisme du lentivirus dans une rétine en dégénérescence. Ce lentivirus est connu pour transduire efficacement les cellules de l'épithélium pigmentaire rétinien dans l'oeil adulte sain, ainsi que celles de la neurorétine, mais ce, uniquement durant le développement. On sait aussi que le vecteur lentiviral présente un tropisme différent selon les enveloppes dont il est muni ; par exemple, le lentivirus avec une enveloppe Mokola est connu pour transduire les cellules gliales du système nerveux central. La rétine qui dégénère montre quant à elle des changements de sa structure qui pourraient influencer la diffusion du vecteur et/ou son tropisme. Le postulat de base a été le suivant : chez l'adulte, la transduction des neurones de la rétine via le lentivirus pourrait être facilitée par l'altération de la membrane limitante externe induite par la dégénérescence (meilleure pénétrance du virus). D'un point de vue technique, nous avons utilisé deux types distincts de modèles murins de dégénérescence rétinienne : des souris Balb/C soumises à une dose toxique de lumière et les souris Rhodopsin knockout, animaux génétiquement modifiés. Comme vecteur viral, nous avons employé deux différents pseudotypes de lentivirus (caractérisés par les enveloppes virales) avec différents promoteurs (séquence d'ADN qui initie la transduction et confère la spécificité d'expression d'un gène). En changeant l'enveloppe et le promoteur, nous avons essayé de trouver la meilleure combinaison pour augmenter l'affinité du vecteur vis-à-vis des photorécepteurs d'abord, puis vis-à-vis d'autres cellules de la rétine. Nos résultats ont montré que la membrane limitante externe est effectivement altérée chez les deux modèles de dégénérescence, mais que cette modification ne favorise pas la transduction des photorécepteurs lorsqu'on utilise un vecteur lentiviral contenant une enveloppe VSVG et un promoteur photorécepteur-spécifique ou ubiquitaire. En effet, une forte réaction gliale a été observée. Par contre, en utilisant le lentivirus avec une enveloppe Mokola et un promoteur ubiquitaire, nous avons constaté une très bonne transduction au niveau des cellules de Millier dans la rétine en dégénérescence, phénomène non observé chez les souris sauvages. Ce travail a donc permis de trouver un vecteur viral efficace pour atteindre et transduire les cellules de Miiller, ceci seulement pendant la dégénérescence de la rétine. Ces cellules, une fois transduites, pourraient être utilisées pour sécréter dans la rétine des agents thérapeutiques tels que des facteurs neurotrophiques pour soutenir la survie des photorécepteurs ou des facteurs anti-angiogéniques pour prévenir la néo-vascularisation lors de diabète ou de dégénérescence maculaire liée à l'âge. - In normal mice, the lentiviral vector (LV) is very efficient to target the RPE cells, but transduces retinal neurons well only during development. In the present study, the tropism of LV has been investigated in the degenerating retina of mice, knowing that the retina structure changes during degeneration. We postulated that the viral transduction would be increased by the alteration of the iuter limiting membrane (OLM). Two different LV pseudotypes were tested using the VSVG arid the Mokola envelopes, as well as two animal models of retinal degeneration: light-damaged Balb-C and Rhodopsin knockout (Rho-/-) mice. After light damage, the OLM is altered and no significant increase of the number of transduced photoreceptors can be obtained with a LV-VSVG-Rhop-GFP vector. In the Rho-/- mice, an altération of the OLM was also observed, but the possibility of transducing photoreceptors was decreased, probably by ongoing gliosis. The use of a ubiquitous promoter allows better photoreceptor transduction, suggesting that photoreceptór-specific promoter activity change during late stages of photoreceptor degeneration. However, the number of targeted photoreceptors remains low. In contrast, LV pseudotyped with the tfokola envelope allows a wide dispersion of the ctor into the retina (corresponding to the injection bleb) with preferential targeting of Muller cells, a situation Mc\ does ot occur in the wild- type retina. Mokola-pseudotyped lentiviral vectors may serve to engineer these glial cells to deliver secreted therapeutic factors to a diseased area of the retina.

Comparative testing of a miniature diffusion size classifier to assess airborne ultrafine particles under field conditions

Miniature diffusion size classifiers (miniDiSC) are novel handheld devices to measure ultrafine particles (UFP). UFP have been linked to the development of cardiovascular and pulmonary diseases; thus, detection and quantification of these particles are important for evaluating their potential health hazards. As part of the UFP exposure assessments of highwaymaintenance workers in western Switzerland, we compared a miniDiSC with a portable condensation particle counter (P-TRAK). In addition, we performed stationary measurements with a miniDiSC and a scanning mobility particle sizer (SMPS) at a site immediately adjacent to a highway. Measurements with miniDiSC and P-TRAK correlated well (correlation of r = 0.84) but average particle numbers of the miniDiSC were 30%âeuro"60% higher. This difference was significantly increased for mean particle diameters below 40 nm. The correlation between theminiDiSC and the SMPSduring stationary measurements was very high (r = 0.98) although particle numbers from the miniDiSC were 30% lower. Differences between the three devices were attributed to the different cutoff diameters for detection. Correction for this size dependent effect led to very similar results across all counters.We did not observe any significant influence of other particle characteristics. Our results suggest that the miniDiSC provides accurate particle number concentrations and geometric mean diameters at traffic-influenced sites, making it a useful tool for personal exposure assessment in such settings.