Thermal tolerance, climatic variability and latitude

The greater latitudinal extents of occurrence of species towards higher latitudes has been attributed to the broadening of physiological tolerances with latitude as a result of increases in climatic variation. While there is some support for such patterns in climate, the physiological tolerances of species across large latitudinal gradients have seldom been assessed. Here we report findings for insects based on published upper and lower lethal temperature data. The upper thermal limits show little geographical variation. In contrast, the lower bounds of supercooling points and lower lethal temperatures do indeed decline with latitude. However, this is not the case for the upper bounds, leading to an increase in the variation in lower lethal limits with latitude. These results provide some support for the physiological tolerance assumption associated with Rapoport's rule, but highlight the need for coupled data on species tolerances and range size

Cytochemical techniques and energy-filtering transmission electron microscopy applied to the study of parasitic protozoa

The study of parasitic protozoa plays a major role in cell biology, biochemistry and molecular biology. Numerous cytochemical techniques have been developed in order to unequivocally identify the nature of subcellular compartments. Enzyme and immuno-cytochemistry allow the detection of, respectively, enzymatic activity products and antigens in particular sites within the cell. Energy-filtering transmission electron microscopy permits the detection of specific elements within such compartments. These approaches are particularly useful for studies employing antimicrobial agents where cellular compartments may be destroyed or remarkably altered and thus hardly identified by standard methods of observation. In this regard cytochemical and spectroscopic techniques provide valuable data allowing the determination of the mechanisms of action of such compounds

Table ronde sur la place de la chirurgie dans les douleurs chroniques du membre supérieur

RésuméLa douleur chronique est d’origine plurifactorielle, elle réalise une véritable maladie à la fois neuromusculaire et psychosociale. Elle met en jeu l’individu dans sa globalité. Il ne faut pas limiter la consultation à une approche uniquement physique et ne pas s’abriter derrière des examens complémentaires inutiles. Il faut savoir écouter le patient, rechercher des éléments de catastrophisme, une hypervigilance, une stratégie d’évitement et évaluer le contexte socioprofessionnel. Le rôle des facteurs psychosociaux est déterminant dans le processus de chronicisation de la douleur et quant aux possibilités de réinsertion professionnelle. La place de la chirurgie peut se résumer au traitement d’une épine irritative (facteur déclenchant) sous réserve qu’elle soit toujours active et que sa suppression permette la régression de l’ensemble du tableau. Mais, le plus souvent, les signes sont mal limités avec une hypersensibilisation plus ou moins diffuse et un dysfonctionnement secondaire de l’ensemble du membre supérieur, une exclusion fonctionnelle et des éléments de déconditionnement sont présents et le contexte psychosocial est défavorable. La prise en charge ne peut alors être que pluridisciplinaire et réalisée au mieux en centre de réadaptation

Digestive and appendicular soft-parts, with behavioural implications, in a large Ordovician trilobite from the Fezouata Lagerstätte, Morocco

Trilobites were one of the most successful groups of marine arthropods during the Palaeozoic era, yet their soft-part anatomy is only known from a few exceptionally-preserved specimens found in a handful of localities from the Cambrian to the Devonian. This is because, even if the sclerotized appendages were not destroyed during early taphonomic stages, they are often overprinted by the three-dimensional, mineralised exoskeleton. Inferences about the ventral anatomy and behavioural activities of trilobites can also be derived from the ichnological record, which suggests that most Cruziana and Rusophycus trace fossils were possibly produced by the actions of trilobites. Three specimens of the asaphid trilobite Megistaspis (Ekeraspis) hammondi, have been discovered in the Lower Ordovician Fezouata Konservat-Lagerstätte of southern Morocco, preserving appendages and digestive tract. The digestive structures include a crop with digestive caeca, while the appendages display exopodal setae and slight heteropody (cephalic endopods larger and more spinose than thoracic and pygidial ones). The combination of these digestive structures and the heteropody has never been described together among trilobites, and the latter could assist in the understanding of the production of certain comb-like traces of the Cruziana rugosa group, which are extraordinarily abundant on the shallow marine shelves around Gondwana.This work has been supported by the Spanish Ministry of Economy and Competitiveness, project number CGL2012- 39471/BTE.Peer reviewe

Possible detection of phase changes from the non-transiting planet HD 46375b by CoRoT

The present work deals with the detection of phase changes in an exoplanetary system. HD 46375 is a solar analog known to host a non-transiting Saturn-mass exoplanet with a 3.0236 day period. It was observed by the CoRoT satellite for 34 days during the fall of 2008. We attempt to identify at optical wavelengths, the changing phases of the planet as it orbits its star. We then try to improve the star model by means of a seismic analysis of the same light curve and the use of ground-based spectropolarimetric observations. The data analysis relies on the Fourier spectrum and the folding of the time series. We find evidence of a sinusoidal signal compatible in terms of both amplitude and phase with light reflected by the planet. Its relative amplitude is Delta Fp/F* = [13.0, 26.8] ppm, implying an albedo A=[0.16, 0.33] or a dayside visible brightness temperature Tb ~ [1880,2030] K by assuming a radius R=1.1 R_Jup and an inclination i=45 deg. Its orbital phase differs from that of the radial-velocity signal by at most 2 sigma_RV. However, the tiny planetary signal is strongly blended by another signal, which we attribute to a telluric signal with a 1 day period. We show that this signal is suppressed, but not eliminated, when using the time series for HD 46179 from the same CoRoT run as a reference. This detection of reflected light from a non-transiting planet should be confirmable with a longer CoRoT observation of the same field. In any case, it demonstrates that non-transiting planets can be characterized using ultra-precise photometric lightcurves with present-day observations by CoRoT and Kepler. The combined detection of solar-type oscillations on the same targets (Gaulme et al. 2010a) highlights the overlap between exoplanetary science and asteroseismology and shows the high potential of a mission such as Plato.Comment: 4 pages, 6 figure

Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD 163296: evidence of refractory dust?

This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.We present new long-baseline spectro-interferometric observations of the Herbig Ae star HD 163296 (MWC 275) obtained in the H and K bands with the AMBER instrument at the VLTI. The observations cover a range of spatial resolutions between ∼3 and ∼12 milliarcseconds, with a spectral resolution of ∼30. With a total of 1481 visibilities and 432 closure phases, they represent the most comprehensive (u, v) coverage achieved so far for a young star. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD 163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model in which a dominant contribution to the H and K band emission originates in an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At a distance of 0.45 AU from the star, silicates condense, the disk becomes optically thick and develops a puffed-up rim, whose skewed emission can account for the non-zero closure phases. We discuss the source of the inner disk emission and tentatively exclude dense molecular gas as well as optically thin atomic or ionized gas as its possible origin. We propose instead that the smooth inner emission is produced by very refractory grains in a partially cleared region, extending to at least ∼0.5 AU. If so, we may be observing the disk of HD 163296 just before it reaches the transition disk phase. However, we note that the nature of the refractory grains or, in fact, even the possibility of any grain surviving at the very high temperatures we require (∼2100−2300 K at 0.1 AU from the star) is unclear and should be investigated further.We acknowledge fundings from CNRS and INAF (grant ASI-INAF I/016/07/0). This work was in part performed under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Michelson Fellowship Progra

Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD163296: evidence for refractory dust?

We present new long-baseline spectro-interferometric observations of the HerbigAe star HD163296 obtained in the H and K bands with the AMBER instrument at VLTI. The observations cover a range of spatial resolutions between 3 and 12 milli-arcseconds, with a spectral resolution of ~30. With a total of 1481 visibilities and 432 closure phases, they result in the best (u,v) coverage achieved on a young star so far. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model where a dominant contribution to the H and K band emissions arises from an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At the latter distance from the star, silicates condense, the disk becomes optically thick and develops a puffed-up rim, whose skewed emission can account for the non-zero closure phases. We discuss the nature of the inner disk emission and tentatively rule out dense molecular gas as well as optically thin atomic or ionized gas as its possible origin. We propose instead that the inner emission traces the presence of very refractory grains in a partially cleared region, extending at least to 0.5 AU. If so, we may be observing the disk of HD163296 just before it reaches the transition disk phase. However, we note that the nature of the refractory grains or even the possibility for any grain to survive at the very high temperatures we require (~2100-2300 K at 0.1 AU from the star) is unclear and should be investigated further.Comment: 14 pages; 12 figures; accepted by A&

DETC Induces Leishmania Parasite Killing in Human In Vitro and Murine In Vivo Models: A Promising Therapeutic Alternative in Leishmaniasis

Background: Chemotherapy remains the primary tool for treatment and control of human leishmaniasis. However, currently available drugs present serious problems regarding side-effects, variable efficacy, and cost. Affordable and less toxic drugs are urgently needed for leishmaniasis. Methodology/Principal Findings: We demonstrate, by microscopy and viability assays, that superoxide dismutase inhibitor diethyldithiocarbamate (DETC) dose-dependently induces parasite killing (p,0.001) and is able to ??????sterilize?????? Leishmania amazonensis infection at 2 mM in human macrophages in vitro. We also show that DETC-induced superoxide production (p,0.001) and parasite destruction (p,0.05) were reverted by the addition of the antioxidant N-acetylcysteine, indicating that DETC-induced killing occurs through oxidative damage. Furthermore, ultrastructural analysis by electron microscopy demonstrates a rapid and highly selective destruction of amastigotes in the phagosome upon DETC treatment, without any apparent damage to the host cell, including its mitochondria. In addition, DETC significantly induced parasite killing in Leishmania promastigotes in axenic culture. In murine macrophages infected with Leishmania braziliensis, DETC significantly induced in vitro superoxide production (p = 0.0049) and parasite killing (p = 0.0043). In vivo treatment with DETC in BALB/C mice infected with Leishmania braziliensis caused a significant decrease in lesion size (p,0.0001), paralleled by a 100-fold decrease (p = 0.0087) in parasite burden. Conclusions/Significance: Due to its strong leishmanicidal effect in human macrophages in vitro, its in vivo effectiveness in a murine model, and its previously demonstrated in vivo safety profile in HIV treatment, DETC treatment might be considered as a valuable therapeutic option in human leishmaniasis, including HIV/Leishmania co-infection

Oxygen as a Driver of Early Arthropod Micro-Benthos Evolution

BACKGROUND: We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. METHODOLOGY/PRINCIPAL FINDINGS: The PO(2) of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO(2) of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O(2). Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O(2) levels. The PO(2) of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O(2). Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO(2) gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O(2). Ostracods became the numerically dominant arthropod micro-benthos of the Phanerozoic. CONCLUSIONS/SIGNIFICANCE: Our work has implications from an evolutionary context for understanding how oxygen-level in marine ecosystems drives behaviour