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The present study examined changes in biometric characteristics, osmoregulatory capacity, and seawater (SW) tolerance of juvenile sea lamprey (Petromyzon marinus) throughout the varying thermal changes from late autumn to late spring. Body length, mass, and condition factor were maintained until April, when significant declines in mass and condition factor were observed to correspond with increases in temperature. Nearly 100% survival in SW was maintained through April. In May, after river and estuarine temperatures had increased, significant mortality in SW (up to 50%) was observed. After SW acclimation, plasma chloride was maintained at an elevated set point, and gill [Na.sup.+]/[K.sup.+]-ATPase activity was elevated. Neither parameter appeared to be affected during springtime warming. Together, these results provide a first characterization of the sustained osmoregulatory performance of juvenile sea lamprey after metamorphosis and show that the window of increased hypoosmoregulatory performance for SW entry lasts for at least 5 months but may ultimately be limited by increases in river water temperatures in late spring. Key words: sea lamprey, osmoregulation, salinity, migration, temperature, Introduction Sea lamprey (Petromyzon marinus) is an anadromous fish of North America and Europe. Like all anadromous fishes, sea lamprey make a freshwater (FW)-to-seawater (SW) migration as juveniles to access [...]

Anuran amphibians that breed in ephemeral ponds of unpredictable environments have mechanisms to tolerate or to avoid associated risks of egg and tadpole mortality, such as selection of oviposition sites, plasticity in larval development, and resistance of eggs to desiccation. The Yungas Red-belly Toad (Melanophryniscus rubriventris (Vellard, 1947)) breeds in temporary ponds in the Andean Yungas under unpredictable events of flooding and droughts of reproductive sites. To determine whether this species possesses any developmental mechanisms to deal with the environmental conditions, we experimentally evaluated the resistance of eggs subjected to different times of exposure to air and the tadpoles to different levels of pond desiccation. The species has not developed mechanisms of resistance of its eggs or phenotypic plasticity to the recurrent risks of pond desiccation, and mass mortality is a common event. In such a context, explosive breeding highly synchronized with rainfall, together with fast larval development, seems to be vitally important at these places where the duration of ponds is short and unpredictable. Key words: Anura, developmental plasticity, eggs, Melanophryniscus rubriventris,pond desiccation,tadpoles, unpredictable environmental conditions, Yungas Red-belly Toad. Les anoures amphibiens qui se reproduisent dans des etangs ephemeres de milieux aux conditions imprevisibles ont recours a divers mecanismes leur permettant de tolerer ou d'eviter les risques associes de mortalite des oeufs et des tetards, comme la selection du site de ponte, la plasticite du developpement des larves et la resistance a la dessiccation des oeufs. Le crapaud a ventre rouge (Melanophryniscus rubriventris (Vellard, 1947)) se reproduit dans des etangs provisoires des Yungas andines dans des conditions imprevisibles d'inondation et de dessiccation des sites de reproduction. Afin de determiner si cette espece a recours a des mecanismes developpementaux lui permettant de resister aux conditions ambiantes, nous evaluons de maniere experimentale la resistance a l'exposition a l'air plus ou moins longue desc oeufs et la resistance des tetards a differents degres de dessiccation de l'etang. L'espece n'a pas developpe de mecanisme de resistance des oeufs, ni une plasticite phenotypique lui permettant de s'adapter aux risques recurrents de dessiccation de l'etang, et le phenomene de mortalite massive est chose courante. Dans ce contexte, la reproduction explosive etroitement synchronisee avec les episodes de pluie, combinee au developpement rapide des larves, semble etre d'importance vitale dans les endroits ou la presence d'etangs est courte et imprevisible. [Traduit par la Redaction] Mots-cles : anoures, plasticite developpementale, oeufs, Melanophryniscus rubriventris, dessiccation de l'etang, tetards, conditions ambiantes imprevisibles, crapaud a ventre rouge des Yungas., Introduction From an evolutionary perspective, one of the fundamental issues faced by organisms is the successful use of environmental resources to survive and reproduce. Natural selection favors resource allocation strategies [...]

For freshwater fishes, elevated water temperatures associated with climate warming and hypoxia can co-occur and are likely to interact as both affect oxidative metabolism. We quantified the effects of acclimation to elevated temperature and hypoxia on the thermal tolerance of pugnose shiner (Notropis anogenus), a cyprinid fish threatened in its Canadian range. In one experiment, pugnose shiner underwent two-week sequential acclimations to six increasing temperatures. Fish acclimated to warmer waters increased their critical thermal maximum (C[T.sub.max]), while the agitation temperature ([T.sub.ag]) was 3.4[degrees]C lower than the C[T.sub.max]. In another experiment, fish were acclimated to three dissolved oxygen treatments (>95%, ~56%, or ~40% air saturation) for two weeks and tested under >95% and 40% conditions. C[T.sub.max] was lower when measured under 40% for normoxia-acclimated fish but not for hypoxia-acclimated fish. Hypoxia-acclimated fish had higher [T.sub.ag] and smaller agitation windows than normoxia-acclimated fish, suggesting that hypoxia acclimation improves aspects of thermal tolerance. We examine the plasticity of thermal tolerance of pugnose shiner, showing that they may be more vulnerable to high temperatures compared with other non-imperiled Notropis species. Pour les poissons d'eau douce, des temperatures elevees de l'eau associees au rechauffement climatique et l'hypoxie peuvent se produire simultanement et sont susceptibles d'interagir, puisque les deux phenomenes ont une incidence sur le metabolisme oxydatif. Nous avons quantifie les effets de l'acclimatation a des temperatures elevees et a l'hypoxie sur la tolerance thermique du mene camus (Notropis anogenus), un cyprinide menace dans son aire de repartition canadienne. Dans une experience, des menes camus ont ete assujettis a des acclimatations sequentielles de deux semaines a six temperatures de plus en plus elevees. La temperature maximum critique (C[T.sub.max]) des poissons acclimates a des eaux plus chaudes a augmente, alors que la temperature d'agitation ([T.sub.ag]) etait de 3,4[degrees]C inferieure a la C[T.sub.max]. Dans une autre experience, des poissons ont ete acclimates a trois traitements d'oxygene dissous (saturations en air de >95, ~56 ou ~40 %) pendant deux semaines, puis evalues dans des conditions de saturation en air de >95 % et 40 %. La C[T.sub.max] mesuree a une saturation en air de 40 % etait plus faible pour les poissons acclimates a la normoxie, mais non pour les poissons acclimates a l'hypoxie. Ces derniers presentaient une [T.sub.ag] plus elevee et des fenetres d'agitation plus petites que les poissons acclimates a la normoxie, donnant a penser que l'acclimatation a l'hypoxie ameliore certains aspects de la tolerance thermique. Nous examinons la plasticite de la tolerance thermique des menes camus et demontrons qu'ils pourraient etre plus vulnerables aux temperatures elevees que d'autres especes de Notropis non en peril. [Traduit par la Redaction], Introduction Freshwater organisms face multiple threats associated with land conversion, influx of pollutants and contaminants, hypoxia, overharvesting, and species invasions (Dudgeon et al. 2006; Strayer and Dudgeon 2010; Hermoso 2017). [...]

Phenotypic plasticity and local adaptations are important factors in predicting range expansions and shifts of pest insects in a changing climate. We reared two lepidopteran forest pests, Lymantria monacha (Linnaeus) and Lymantria dispar (Linnaeus), at three climatically different field sites from central Germany to northern Finland to investigate differences among populations in plasticity in the timing of pupation and adult emergence (measured as cumulative temperature sums, degree-days >5 [degrees]C), pupal mass, and duration of the pupal period. We also compared the phenologies of continental and boreal L. monacha populations feeding on Scots pine (Pinus sylvestris L.) to reveal possible local adaptations. Lymantria dispar was reared on different host plants, Quercus robur L., Betula pendula Roth, and Betula pubescens ssp. czerepanovii (Orl.) Hamet-Ahti, to evaluate the possibilities of a range expansion northwards. There was stronger indication of adaptive phenotypic plasticity, which enables species to cope with changing environmental conditions, in continental L. dispar and boreal L. monacha populations than in the continental L. monacha population. Differences between boreal and continental L. monacha populations may denote adaptation to local conditions. All three host plants used for L. dispar proved suitable for the species, revealing that host plant availability would not limit its range expansion in northern Europe. Key words: climate change, local adaptation, Lymantria monacha, Lymantria dispar, phenotypic plasticity. La plasticite phenotypique et les adaptations locales sont des facteurs importants lorsqu'il s'agit de prevoir l'expansion et les modifications de l'aire de repartition des insectes ravageurs dans le contexte du changement climatique. Nous avons eleve deux ravageurs forestiers du groupe des lepidopteres, Lymantria monacha (Linnaeus) et Lymantria dispar (Linnaeus), a trois endroits sur le terrain differents du point de vue climatique, allant du centre de l'Allemagne au nord de la Finlande pour etudier les differences parmi les populations du point de vue de la plasticite dans le moment de la nymphose et de l'emergence des adultes (mesuree par la somme cumulative des temperatures, degres-jours >5 [degrees]C), la masse des nymphes et la duree de la periode nymphale. Nous avons aussi compare la phenologie des populations continentale et boreale de L. monacha qui s'attaquent au pin sylvestre (Pinus sylvestris L.) pour trouver d'eventuelles adaptations locales. Lymantria dispar a ete eleve sur differentes plantes hotes, Quercus robur L., Betula pendula Roth et Betula pubescens ssp. czerepanovii (Orl.) Hamet-Ahti, pour evaluer les possibilites d'expansion de son aire de repartition vers le nord. Les indices de plasticite phenotypique adaptative, qui permet aux especes de faire face aux changements des conditions environnementales, etaient plus significatifs chez les populations continentale de L. dispar et boreale de L. monacha que chez la population continentale de L. monacha. Les differences entre les populations boreale et continentale de L. monacha sont peut-etre un indice d'adaptation aux conditions locales. Les trois plantes hotes utilisees dans le cas de L. dispar se sont averees adequates pour cette espece, indiquant que la disponibilite de plantes hotes ne limiterait pas l'expansion de son aire de repartition dans le nord de l'Europe. [Traduit par la Redaction] Mots-cles : changement climatique, adaptation locale, Lymantria monacha, Lymantria dispar, plasticite phenotypique., Introduction The influence of climate change on butterflies and moths, especially charismatic, conspicuous species and those considered as forest or agricultural pests, has been investigated intensively in recent years (e.g., [...]

Abstract: The small extent of seasonally snow-covered Australian mountains means that there has not been a great selective pressure on the mammalian fauna for adaptations to this environment. Only one [...]

Fluctuating asymmetry (FA), random deviations from perfect symmetry in bilateral traits, is a common inverse measure of developmental stability (DS), which is related to one's ability to buffer against environmental and genetic perturbations. There is a widespread hypothesis that heterozygosity grants an increased ability to compensate for developmental errors caused by genetic and environmental factors, rendering homozygous individuals less symmetric than heterozygous ones. In addition, if natural selection on FA is common, nonessential traits should exhibit higher asymmetry than functionally essential traits. This is especially well tested in haplodiploid organisms, which present a clear distinction between 'homo'zygosity (males) and heterozygosity (females). Relatively few FA studies looked at this relationship in hymenopterans or in haplodiploid organisms in general and the results are rather inconsistent. This study compares FA measurements of seven parts of the maxillary palpus, with sclerotized and membranous parts scored separately, and two wing venation characters for males and females of the Chilean bee Xeromelissa rozeni (Toro and Moldenke, 1979). The results of this study suggest that there is an equally strong selection force for maxillary palp symmetry in both males and females leading to a relatively low FA in both sexes, and that less functional traits exhibit higher FA due to relaxation of selection. Lastly, we stress the importance of testing a larger number of independent traits. Key words: developmental instability, haplodiploidy, maxillary palpomeres, essential structures, new species, morphology, Xeromelissa rozeni, colletid bees. L'asymetrie fluctuante (AF), soit des ecarts aleatoires par rapport a la symetrie parfaite des caracteres bilateraux, est une mesure inverse repandue de la stabilite du developpement (SD), qui est reliee a la capacite d'attenuer les effets de perturbations environnementales et genetiques. Une hypothese repandue veut que l'heterozygotie confere une capacite accrue d'attenuer les erreurs de developpement causees par des facteurs genetiques et environnementaux, rendant les individus homozygotes moins symetriques que les heterozygotes. En outre, si la selection naturelle pour l'AF est repandue, les caracteres non essentiels devraient presenter une plus grande asymetrie que les caracteres essentiels sur le plan fonctionnel. Cela est particulierement bien etabli pour les organismes haplodiploides, caracterises par une distinction claire entre l'<< homo >>zygotie (males) et l'heterozygotie (femelles). Assez peu d'etudes de l'AF se sont penchees sur ce lien chez les hymenopteres ou chez les organismes haplodiploides en general, et les resultats ne sont pas tres coherents. La presente etude compare des mesures de l'AF de sept parties du palpe maxillaire, les parties sclerotisees et membraneuses etant notees separement, et deux caracteres de la nervation alaire pour des abeilles chiliennes Xeromelissa rozeni (Toro et Moldenke, 1979) males et femelles. Les resultats donnent a penser que la force de selection pour la symetrie des palpes maxillaires est similaire pour les males et les femelles, se traduisant par une AF relativement faible pour les deux sexes, et que les caracteres moins fonctionnels presentent une AF plus grande en raison du relachement de la selection. Enfin, nous insistons sur l'importance de verifier un grand nombre de caracteres independants. [Traduit par la Redaction] Mots-cles : instabilite du developpement, haplodiploidie, palpomeres maxillaires, structures essentielles, nouvelle espece, morphologie, Xeromelissa rozeni, colletides., Introduction Fluctuating asymmetry (FA), random deviations from perfect symmetry in bilateral traits, is one of three types of recognized asymmetry (Palmer and Strobeck 1986). The others are directional asymmetry (DA) [...]

Purpose: We tested whether using hearing aids can improve unaided performance in speech perception tasks in older adults with hearing impairment. Method: Unaided performance was evaluated in dichotic listening and speech-in-noise tests in 47 older adults with hearing impairment; 36 participants in 3 study groups were tested before hearing aid fitting and after 4, 8, and 14 weeks of hearing-aid use. The remaining 11 participants served as a control group and were similarly evaluated but were not fitted with hearing aids. Three protocols were compared in the study groups: amplification for the nondominant ear, amplification for the dominant ear, and bilateral amplification. Subsequently, after 4 weeks, all participants were afforded bilateral amplification. Results: In the study groups, unaided dichotic listening scores improved significantly in the nondominant ear by 8 weeks and onward. Significant improvements were also observed for unaided speech identification in noise, with some gains apparent after 4 weeks of hearing-aid use. No gains were observed in the control group. Conclusions: Using hearing aids for a relatively short period can induce changes in the way older adults process auditory inputs in perceptual tasks such as speech identification in noise and dichotic listening. These changes suggest that the central auditory system of older adults retains the potential for behaviorally relevant plasticity., The difficulties faced by older adults when attempting to understand speech in nonoptimal conditions such as noisy and multiple-talker environments are well documented (e.g., Divenyi & Haupt, 1997; Schneider & [...]

Anuran survival is strongly affected by exposure to high environmental temperatures. However, their upper thermal tolerances vary between species and within developmental stages. The aims of this research were to measure the median lethal temperature ([LT.sub.50]) of three anuran developmental stages (Gosner stages 10,20, and 25) at a constant thermal regime, and of developing embryos (stage 10) until they became tadpoles (stage 25) exposed to daily peaks of temperatures between 1000 and 1600. Four Colombian species (Emerald-eyedTreefrog, Hypsiboas crepitans (Wied-Neuwied, 1824); Tungara Frog, Engystomops pustulosus (Cope, 1864); Rivero's Toad, Rhinella humboldti (Gallardo, 1965); Emerald Glassfrog, Espadarana prosoblepon (Boettger, 1892)) were used in these experiments. An ontogenetic increase was observed in the upper thermal tolerance from embryos to tadpoles for all species studied. In addition, developing embryos exposed to peak temperatures showed a [LT.sub.50] fairly close to the mean of the maximum habitat temperatures, particularly in H. crepitans and E. pustulosus that lay egg masses exposed directly to the sun. Environmental temperatures in the microhabitat of species studied showed values remarkably higher than their experimental [LT.sub.50]. Therefore, we postulate that rapid increases in environmental temperatures, as result of global or local changes, might be a critical factor for anuran survival, mainly during the embryonic stages when they are more sensitive to temperature. Key words: amphibians, global warming, [LT.sub.50], survival, temperature. L'exposition a des temperatures ambiantes elevees exerce une forte influence sur la survie des anoures. Toutefois, les seuils maximums de tolerance a la temperature de ces animaux peuvent varier entre especes et au sein de stades de developpement. Les objectifs de la presente recherche consistaient a mesurer la temperature letale mediane ([LT.sub.50]) de trois stades de developpement des anoures (les stades 10, 20 et 25 de Gosner) pour un regime thermique constant, et d'embryons en developpement (stade 10) jusqu'a ce qu'ils soient devenus des tetards (stade 25), exposes a des pointes quotidiennes de temperature entre 10h00 et 16h00. Les epreuves dans le cadre de ces experiences ont porte sur quatre especes colombiennes : la rainette aux yeux emeraudes, Hypsiboas crepitans (WiedNeuwied, 1824), la grenouille tungara, Engystomopspustulosus (Cope, 1864), le crapaud granuleux, Rhinella humboldti (Gallardo, 1965) et la grenouille de verre Espadarana prosoblepon (Boettger, 1892). Nous avons observe une augmentation ontogenique du seuil maximum de tolerance a la temperature du stade d'embryon a celui de tetard pour toutes les especes etudiees. En outre, les embryons en developpement exposes a des pointes de temperature presentment une [LT.sub.50] assez proche de la moyenne des temperatures maximums de l'habitat, particulierement chez H. crepitans et E. pustulosus, dont les pontes sont directement exposees au soleil. Les temperatures ambiantes dans le microhabitat des especes etudiees presentaient des valeurs considerablement plus elevees que leurs [LT.sub.50] experimentales. Nous postulons donc que l'augmentation rapide des temperatures ambiantes decoulant de changements planetaires ou locaux pourrait constituer un facteur critique pour la survie des anoures, principalement durant les stades embryonnaires, quand leur sensibilite a la temperature est la plus grande. [Traduit par la Redaction] Mots-cles: amphibiens, rechauffement planetaire, [LT.sub.50], survie, temperature., Introduction Environmental temperature dramatically impacts all aspects of amphibian life history (Corn 2005; Li et al. 2013) and consequently is one of the most critical factors affecting the survival of [...]

We evaluated training adaptation and physical performance parameters in rats orally supplemented with glycerol, glucose, or saline, and submitted to moderate aerobic exercise. Thirty male rats were trained for 6 weeks and administered the supplements during the last 4 weeks of the experiment. Animals were distributed in a completely randomized factorial 2 x 3 design (with or without exercise and 3 substrates). Data were subjected to analysis of variance (ANOVA) and means were compared using the Student-Newmann-Keuls test at 5%. Among the trained animals, none of the substances caused differences in the percentages of protein, fat, or water content in the carcass. Compared with the sedentary animals, the trained animals supplemented with saline and glucose showed a higher protein percentage in the carcass. The relative mass of the heart and adrenal glands was higher in the trained animals. Glycerol improved the protein content in non-trained animals and increased the relative adrenal mass in both groups. Glycerol reduced the variation in levels of lactate and aspartate aminotransferase (AST) during the last exercise session. There was no difference between groups regarding the relative mass of the thymus and gastrocnemius or with the diameter of muscle fibers or the neutrophil-lymphocyte ratio. Supplementation with glycerol was efficient at attenuating variation in AST and lactate levels during exercise. Key words: glycerin, nutrition, physical activity, athletes, hyper-hydration. Les auteurs ont evalue les parametres lies a l'adaptation a l'entrainement et la performance physique de rats qui ont recu par voie orale un supplement de glycerol, de glucose ou de saline et qui ont ete soumis a un exercice aerobie modere. Trente rats males ont ete entraines pendant six semaines et ont recu le supplement au cours des quatre dernieres semaines de l'experience. Les animaux ont ete repartis de maniere completement aleatoire selon un plan factoriel 2 x 3 (avec ou sans exercice et les trois substrats). Les donnees ont ete soumises a une analyse de variance et les moyennes ont ete comparees par un test Student-Newman-Keuls a 5%. Chez les animaux entraines, aucune des substances ne causait de difference significative sur le plan du contenu en proteines, en graisses ou en eau des carcasses. Comparativement aux animaux sedentaires, les animaux entraines ayant recu un supplement de saline ou de glucose presentaient un pourcentage de proteines plus eleve dans les carcasses. Le poids relatif du creur et des surrenales etait plus eleve chez les animaux entraines. Le glycerol ameliorait le contenu en proteines chez les animaux non entraines et accroissait le poids relatif des surrenales chez les deux groupes. Le glycerol reduisait la variation des niveaux de lactate et d'aspartate aminotransferase (AST) lors de la derniere session d'exercice. Il n'y avait pas de difference entre les groupes sur le plan de poids relatif du thymus et du muscle gastrocnemien, de meme que du diametre des fibres musculaires et du rapport neutrophiles/lymphocytes. La supplementation en glycerol etait efficace pour attenuer la variation des niveaux d'AST et de lactate durant l'exercice. [Traduit par la Redaction] Mots-cles: glycerine, nutrition, activite physique, athletes, hyperhydratation., Introduction Dietary supplements improve energy supply and physical performance during exercise (Jacobson et al. 2012; Hutchins-Wiese et al. 2013). Glycerol (glycerine) can be used as an ergogenic agent owing to [...]

The origin of tetrapods from their fish antecedents, approximately 400 million years ago, was coupled with the origin of terrestrial locomotion and the evolution of supporting limbs. Polypterus is a member of thebasal- most group of ray - finned fish (actinopterygians) and has many plesiomorphic morphologies that are comparable to elpistostegid fishes, which are stem tetrapods. Polypterus therefore serves as an extant analogue of stem tetrapods, allowing us to examine how developmental plasticity affects the 'terrestrialization' of fish. We measured the developmental plasticity of anatomical and biomechanical responses in Polypterus reared on land. Here we show the remarkable correspondence between the environmentally induced phenotypes of terrestrialized Polypterus and the ancient anatomical changes in stem tetrapods, and we provide insight into stem tetrapod behavioural evolution. Our results raise the possibility that environmentally induced developmental plasticity facilitated the origin of the terrestrial traits that led to tetrapods., The evolution of terrestrial locomotion in vertebrates required the appearance of new behaviours and supporting appendicular structures (1-8). The skeletal changes included the origin of supporting limbs, the decoupling of [...]

Changes in environmental temperature can pose considerable challenges to animals and shifts in thermal habitat have been shown to be a major force driving species' adaptation. These adaptations have been the focus of major research efforts to determine the physiological or metabolic constraints related to temperature and to reveal the phenotypic characters that can or should adjust. Considering the current consensus on climate change, the focus of research will likely shift to questioning whether ectothermic organisms will be able to survive future modifications of their thermal niches. Organisms can adjust to temperature changes through physiological plasticity (e.g., acclimation), genetic adaptation, or via dispersal to more suitable thermal habitats. Thus, it is important to understand what genetic and phenotypic attributes--at the individual, population, and species levels--could improve survival success. These issues are particularly important for ectotherms, which are in thermal equilibrium with the surrounding environment. To start addressing these queries, we should consider what physiological or metabolic functions are responsible for the impact of temperature on organisms. Some recent developments indicate that mitochondria are key metabolic structures determining the thermal range that an organism can tolerate. The catalytic capacity of mitochondria is highly sensitive to thermal variation and therefore should partly dictate the temperature dependence of biological functions. Mitochondria contain a complex network of different enzymatic reaction pathways that interact synergistically. The precise regulation of both adenosine triphosphate (ATP) and reactive oxygen species (ROS) production depends on the integration of different enzymes and pathways. Here, we examine the temperature dependence of different parts of mitochondrial pathways and evaluate the evolutionary challenges that need to be overcome to ensure mitochondrial adaptations to new thermal environments. Key words: respiration, temperature, ectotherms, energy metabolism, adaptation, acclimation, reactive oxygen species, mitochondrial DNA. Les changements aux temperatures ambiantes peuvent poser d'importants defis pour les animaux et il a ete demontre que la modification des habitats thermiques est un important moteur d'adaptation des especes. Ces adaptations ont fait l'objet d'efforts de recherche considerables visant a etablir les contraintes physiologiques ou metaboliques associees a la temperature, ainsi qu'a deceler les caracteres phenotypiques qui pourraient ou devraient s'ajuster. Etant donne le consensus actuel sur les changements climatiques, les efforts de recherche futurs s'axeront vraisemblablement sur le potentiel de survie des organismes ectothermes aux modifications futures de leurs niches thermiques. Pour s'ajuster aux changements thermiques, les organismes peuvent faire appel a la plasticite physiologique (p. ex. acclimatation), l'adaptation genetique ou la dispersion vers des habitats thermiques plus convenables. Il importe donc de comprendre les attributs genetiques et phenotypiques--au niveau individuel, de la population et de l'espece--qui pourraient ameliorer la survie. Ces questions sont d'autant plus importantes pour les ectothermes, qui sont en equilibre thermique avec le milieu ambiant. Pour tenter de repondre a ces questions, il convient de se pencher sur les fonctions physiologiques et metaboliques qui pourraient dicter l'incidence de la temperature sur les organismes. Certaines avancees recentes indiquent que les mitochondries constituent des structures metaboliques cles pour la determination de la plage de temperatures qu'un organisme peut tolerer. La capacite catalytique des mitochondries est extremement sensible aux variations thermiques et devrait donc dicter, en partie du moins, l'influence de la temperature sur les fonctions biologiques. Les mitochondries renferment un reseau complexe de voies de reaction enzymatique distinctes qui interagissent de maniere synergetique. La regulation exacte de la production d'adenosine triphosphate (ATP) et de derives reactifs de l'oxygene (DRO) depend de l'integration de differentes enzymes et voies. Nous examinons l'influence de la temperature sur differentes parties de voies mitochondriales et evaluons les deis evolutifs devant etre surmontes pour permettre des adaptations mitochondriales a de nouveaux environnements thermiques. [Traduit par la Redaction] Mots-cles : respiration, temperature, ectothermes, metabolisme energetique, adaptation, acclimatation, derives reactifs de l'oxygene, ADN mitochondrial., Introduction Temperature has been a challenge to which animals have successfully adapted over evolutionary time. These adaptations to a wide range of thermal niches or temperature fluctuations have been the [...]

Fish navigate mazes more quickly and efficiently after a regimen of jumping about on a solid surface. Fish navigate mazes more quickly and efficiently after a regimen of jumping about on a solid surface., Author Affiliations: The mangrove killifish is a quicker study after spending bouts of time in air, experiments show. Credit: Pally/Alamy Mangrove killifish Amphibious fish get smart -- by working out [...]

Increasing dissolution of anthropogenic-released carbon dioxide into the world's oceans is causing ocean acidification (OA). OA is thought to negatively affect most marine-calcifying organisms, notably cold-water corals (CWC), which may be especially sensitive due to the deep and cold waters they normally thrive in. However, the impact of OA on CWC is difficult to predict. Recorded distributions of CWC are rarely linked to in situ water chemistry, and the boundaries of their distributions are not clearly defined. The fjord Comau in Chilean Patagonia features pronounced pH gradients, and up to 0.5 pH units have been recorded both vertically (at some sites within 50 m depth) and less distinct horizontally (from head to mouth). The cosmopolite coral Desmophyllum dianthus grows along the course of the fjord and of the entire pH range. It occurs in shallow depths (below 12 m, pH 8.1) as part of a deep-water emergence community, but also in 225 m depth at a pH of 7.4. Based on pH and total alkalinity, data calculations of the associated carbonate chemistry revealed that this CWC thrives commonly close the aragonite (the orthogonal crystal form of calcium carbonate, the mineral structure of coral skeletons) saturation horizon and even below. This suggests a high adaptation potential of D. dianthus to adjust its calcification performance to conditions thermodynamically unfavourable for the precipitation of aragonite., Introduction The changing conditions of the oceans caused by increasing anthropogenic carbon dioxide (C[O.sub.2]) emissions and the ensuing ocean acidification (OA, Crowley 2000; Caldeira and Wickett 2005)raised growing concern in [...]

Most molluscs perform respiration using gills, but the pulmonate molluscs have developed a primitive lung with which they perform pulmonary respiration. The flow of air into this lung occurs through an opening called the pneumostome, and pulmonate molluscs travel to the surface of the water to obtain oxygen from the surrounding atmosphere. The aerial respiratory behaviour of the pulmonate mollusc, the great pond snail (Lymnaea stagnalis (L., 1758)), has been well studied, and a three-neuron central pattern generator (CPG) controlling this rhythmic behaviour has been identified. The aerial respiratory behaviour of L. stagnalis can be operantly conditioned and plasticity within the CPG has been associated with the conditioned response. In this review, we describe both the aerial respiratory behaviour and the underlying neuronal network of this pulmonate mollusc, and then discuss both the behavioural and network plasticity that results from the conditioning of this behaviour. Key words: Lymnaea stagnalis, great pond snail, central pattern generator, aerial respiration, operant conditioning, neural plasticity. Si la respiration chez la plupart des mollusques s'effectue par l'intermediaire de branchies, les mollusques pulmones ont developpe un poumon primitif qu'ils utilisent pour respirer. L'apport d'air dans ce poumon se fait par une ouverture appelee pneumostome, et les mollusques pulmones se rendent a la surface de l'eau pour obtenir de l'oxygene de l'atmosphere environnant. Le comportement de respiration aerienne du mollusque pulmone, la grande lymnee des etangs (Lymnaea stagnalis (L., 1758)), a ete largement etudie, et un generateur central de patrons (CPG) a trois neurones qui controle ce comportement rythmique a ete cerne. Le comportement de respiration aerienne de L. stagnalis peut faire l'objet d'un conditionnement operant, et une plasticite dans le CPG a ete associee a la reponse conditionnee. Dans la presente synthese, nous decrivons le comportement de respiration aerienne et le reseau neuronal sous-jacent de ce mollusque pulmone, puis discutons de la plasticite comportementale et du reseau qui resulte du conditionnement de ce comportement. [Traduit par la Redaction] Mots-cles : Lymnaea stagnalis, grande lymnee des etangs, generateur central de patrons, respiration aerienne, conditionnement operant, plasticite neuronale., An introduction to molluscan respiration Mollusca is a large phylum of at least 50 000 invertebrate species that inhabit marine, freshwater, and terrestrial environments. The body plan of molluscs is [...]

Over the last three decades, the rusty crayfish (Orconectes rusticus (Girard, 1852)) has been expanding its range northward via human-mediated dispersal. If this species is to continue expanding its range northward, it will move onto the Canadian Shield, where calcium (Ca) availability is low and is predicted to decline further in the future. Dissolved Ca is a vital functional component of mollusc and crustacean physiology, important for exoskeletal condition and strength, as well as metabolic activity. However, some organisms are able to compensate for reduced structural integrity by modifying their behaviour. In this study, we asked if the invasive O. rusticus can survive low levels of ambient Ca and, if it can, whether it exhibits modified antipredator behavior in response to the physiological limitations imposed by low [Ca]. We found that, under reduced Ca levels, O. rusticus reduced the frequency of standard activities (such as grooming and foraging) and was more likely to engage in vigilance and (or) escape behavior. We also found that some individuals, in extremely low [Ca], died while molting. This study suggests that Ca limitation on the Shield, especially where predators are present, may limit the northward expansion of O. rusticus beyond their current range limit. Key words: Orconectes rusticus, rusty crayfish, invasive species, environmental change, low calcium waters, antipredator behavior, abiotic tolerance. Au cours des trois dernieres decennies, l'ecrevisse americaine (Orconectes rusticus (Girard, 1852)) a elargi sa repartition geographique vers le nord grace a la dispersion facilitee par les humains. La poursuite de cette expansion vers le nord se traduirait par l'introduction de l'espece dans le Bouclier canadien, ou la disponibilite du calcium (Ca) est faible et devrait continuer de diminuer. Le Ca dissout est un composant fonctionnel essentiel de la physiologie des mollusques et crustaces et est un facteur important pour l'etat et la force de l'exosquelette, ainsi que l'activite metabolique. Certains organismes peuvent toutefois pallier une reduction de leur integrite structurale en modifiant leur comportement. Dans la presente etude, nous nous sommes demande si O. rusticus introduites peuvent survivre a de faibles teneurs en Ca ambiant et, le cas echeant, si elles presentent un comportement antipredateur modifie en reponse aux limites physiologiques imposees par de faibles [Ca]. Nous avons constate que, dans des conditions de concentrations de Ca reduites, O. rusticus reduisait la frequence de ses activites normales (telles que la toilette et la quete de nourriture) et etait plus susceptible d'adopter des comportements de vigilance ou de fuite. Nous avons egalement note que, dans des conditions de [Ca] extremement faibles, certains individus mourraient lors de la mue. L'etude suggere que la disponibilite limitee du Ca dans le Bouclier canadien, particulierement la ou des predateurs sont presents, pourrait limiter l'expansion vers le nord d'O. rusticus au-dela de la limite actuelle de son aire de repartition. [Traduit par la Redaction] Mots-cles: Orconectes rusticus, ecrevisse americaine, espece envahissante, modification de l'environnement, eaux pauvres en calcium, comportement antipredateur, tolerance abiotique., Introduction Invasive species and environmental change or degradation are recognized as the greatest threats to aquatic ecosystems (reviewed in Geist 2011). When invasive species disperse into a new area, it [...]

Although there is significant genetic diversity among populations of the hydroid Cordylophora caspia, the species has not been split into multiple species or subspecies, in part because its members also show great physiological and morphological plasticity. This plasticity makes new taxonomic units hard to define or identify and obscures the connection between historically used names and the genetically defined clades. We explore variation in nematocysts, a character system not previously assessed in Cordylophora but which has demonstrated phylogenetic signal in other cnidarian taxa. We measured more than 5000 capsules from 112 individuals belonging to 14 populations, including representatives of the major genetic lineages. We found no correlation between the size range of capsules and either clade or salinity. Thus, for C. caspia, nematocysts are neither phenotypically plastic with respect to salinity nor taxonomically informative. Nematocyst size and density in particular tissues may be correlated to other environmental factors (such as prey type, size, and abundance in the location of each population) and may aid in distinguishing more distantly related species., Introduction The Ponto-Caspian invasive hydrozoan Cordylophora caspia (Pallas, 1766) is one of only a handful of cnidarians that live in fresh rather than marine waters (Jankowski et al., 2008). It [...]

Pink salmon (Oncorhynchus gorbuscha) enter seawater earlier and smaller (0.2 g) than any other salmonid following a two-stage salinity tolerance process initiated around yolk-sac absorption and completed with seawater entry. For the first time, this two-stage ontogeny of salinity tolerance was characterized by either holding posthatch pink salmon in fresh water or transferring them to seawater every 2 weeks. A window of salinity tolerance around yolk-sac absorption was evidenced by a period of zero morbidity in seawater compared with 100% morbidity for newly hatched alevins and 25% morbidity for fry (~0.2-0.3 g). Increased hypo-osmoregulatory ability at the time of yolk-sac absorption was indicated in fish held in fresh water under constant photoperiod (12 h light : 12 h dark) and temperature (5 °C) by a switch from catabolic to anabolic growth, increased gill [Na.sup.+]K+-ATPase activity and a-1b/a-1a isoform expression, and a plateau in whole-body water content, implying that pink salmon go through a form of smoltification. A large increase in whole-body [[Na.sup.+]] observed in fresh water at yolk-sac absorption may represent a unique strategy for maintaining water balance once fish enter seawater. Le saumon rose (Oncorhynchus gorbuscha) fait son entree en eau de mer plus tot et a plus petite taille (0,2 g) que tout autre salmonide, apres un processus d'adaptation a la salinite en deux etapes debutant aux alentours de l'absorption du sac vitellin et se terminant avec l'entree en eau de mer. Pour la premiere fois, cette ontogenie en deux etapes de la tolerance a la salinite a ete caracterisee soit en maintenant des saumons roses post-eclosion en eau douce ou en les transferant en eau de mer toutes les deux semaines. La presence d'une fenetre de tolerance a la salinite vers le moment de l'absorption du sac vitellin est indiquee par une periode de morbidite nulle en eau de mer, comparativement a une morbidite de 100 % chez les alevins nouvellement eclos et de 25 % pour le fretin (~0,2-0,3 g). Une capacite accrue d'hypoosmoregulation au moment de l'absorption du vitellin etait indiquee chez les poissons maintenus en eau douce dans des conditions de photoperiode (12 h de lumiere : 12 h d'obscurite) et de temperature (5 °C) constantes par le passage d'une croissance catabolique a une croissance anabolique, des augmentations de la [Na.sup.+]K+-ATPase branchiale et du rapport d'expression d'isoformes a-1b/a-1a, et un plafonnement de la teneur corporelle globale en eau, ce qui signifie que le saumon rose subit une forme de smoltification. Une importante augmentation de la [[Na.sup.+]] corporelle globale observee en eau douce au moment de l'absorption du sac vitellin pourrait representer une strategie particuliere de maintien de l'equilibre hydrique une fois que les poissons entrent en eau de mer. [Traduit par la Redaction], Introduction Pink salmon are the most widely distributed and abundant of the Pacific salmon and by number represent two-thirds of the Pacific salmon caught by Canada, the United States, Russia, [...]

ABSTRACT It is well known that immune defenses of bivalves against environmental and pathogenic stresses are primarily attributable to hemocytes. Hemocyte parameters are being used progressively as indicators to assess [...]

A fundamental question in neuroscience is how entire neural circuits generate behaviour and adapt it to changes in sensory feedback. Here we use two-photon calcium imaging to record the activity of large populations of neurons at the cellular level, throughout the brain of larval zebrafish expressing a genetically encoded calcium sensor, while the paralysed animals interact fictively with a virtual environment and rapidly adapt their motor output to changes in visual feedback. We decompose the network dynamics involved in adaptive locomotion into four types of neuronal response properties, and provide anatomical maps of the corresponding sites. A subset of these signals occurred during behavioural adjustments and are candidates for the functional elements that drive motor learning. Lesions to the inferior olive indicate a specific functional role for olivocerebellar circuitry in adaptive locomotion. This study enables the analysis of brain-wide dynamics at single-cell resolution during behaviour., The generation of motor output and the influence of sensory input on future motor programs engage neural activity in many neurons across multiple brain regions. However, past measurements of neural [...]

Diversity and plasticity are hallmarks of cells of the monocyte-macrophage lineage. In response to IFNs, Toll-like receptor engagement, or IL-4/IL-13 signaling, macrophages undergo M1 (classical) or M2 (alternative) activation, which represent extremes of a continuum in a universe of activation states. Progress has now been made in defining the signaling pathways, transcriptional networks, and epigenetic mechanisms underlying M1-M2 or M2-like polarized activation. Functional skewing of mononuclear phagocytes occurs in vivo under physiological conditions (e.g., ontogenesis and pregnancy) and in pathology (allergic and chronic inflammation, tissue repair, infection, and cancer). However, in selected preclinical and clinical conditions, coexistence of cells in different activation states and unique or mixed phenotypes have been observed, a reflection of dynamic changes and complex tissue-derived signals. The identification of mechanisms and molecules associated with macrophage plasticity and polarized activation provides a basis for macrophage-centered diagnostic and therapeutic strategies., Introduction Macrophages are an essential component of innate immunity and play a central role in inflammation and host defense (1). Moreover, these cells fulfill homeostatic functions beyond defense, including tissue [...]

ABSTRACT Shell growth, survival, and physiology were compared between diploid Suminoe (Crassostrea ariakensis) and eastern oysters (Crassostrea virginica) under conditions simulating a U.S. subtropical estuary. Two age groups (4 mo [...]

The behaviour of intertidal consumers is often tightly constrained to tidal movements, although activity patterns can vary within these constraints. Spatio-temporal variability in behaviour of a limpet, Cellana grata, was analysed over different tidal conditions (spring and neap tides) and during different times of the year (one summer and one winter) at sites in Hong Kong. Activity was generally dictated by tidal movements, being concentrated when animals were awash. Plasticity in behaviour was observed, with some limpets anticipating activity during the summer period and delaying activity during winter time. Limpets were active for a time equal, or slightly less, than time awash. As the time awash exceeded ~14-16 h, however, activity duration decreased. Within this general pattern, tidal variation as well as variation among times of the year was noted, with the lowest dependence on time awash being recorded during winter neap tides. Limpets showed a slight preference for being active during nighttime, which was particularly evident when animals were emersed during the summer period. Although the basic activity in C. grata is constrained to a specific temporal window, this limpet is able to modulate its foraging strategies and resting height, according to local, daily changes in environmental conditions., Author(s): Giacomo Santini [sup.1] , Avis Ngan [sup.2] , Gray A. Williams [sup.2] Author Affiliations: (1) grid.8404.8, 0000000417572304, Department of Evolutionary Biology, University of Florence, , Via Romana 17, 50125, [...]

Urban-adapter species facultatively exploit human-subsidized resources in the urban and suburban matrix. We used the woodchuck (Marmota monax) to study how aspects of autecology in an urban-adapter can vary across a gradient of urbanization. We captured and monitored woodchucks by radiotelemetry in southern Illinois from summer 2007 to spring 2009. We captured 47 woodchucks (19 adults, 19 yearlings, 8 young-of-the-year) during the active seasons, and implanted radiotransmitters in 17 adults and 3 yearlings (13 F, 7 M). Overall annual survival was estimated to be 0.76 ± 0.12, with three confirmed mortalities during the study period. Survival and home-range size did not vary by % urban landcover in a buffer surrounding an individual's home range. Habitat-selection analyses indicated that rural edge was the highest-ranked habitat at the home-range scale, whereas urban cover (specifically, developed areas with human structures) was most highly ranked at the within-home-range scale. Body condition was negatively related to % urban landcover. Overall, our findings indicated no clear relationship between woodchuck ecology and urbanization level within our study area. However, our data on body condition and adipose composition, although preliminary, suggested a possible mechanism for variation in overwinter survival across the urban-rural gradient., INTRODUCTION Anthropogenic effects on landscapes produce major changes in the composition of plant and animal communities as well as the structure and function of ecosystems. Urban development, arguably the longest-lasting [...]

In several murine models of autoimmune arthritis, Th17 cells are the dominant initiators of inflammation. In human arthritis the majority of IL-17--secreting cells within the joint express a cytokine phenotype intermediate between Th17 and Th1. Here we show that Th17/1 cells from the joints of children with inflammatory arthritis express high levels of both Th17 and Th1 lineage-specific transcription factors, RORC2 and T-bet. Modeling the generation of Th17/1 in vitro, we show that Th17 cells 'convert' to Th17/1 under conditions that mimic the disease site, namely low TGF[beta] and high IL-12 levels, whereas Th1 cells cannot convert to Th17. Th17/1 cells from the inflamed joint share T-cell receptor (TCR) clonality with Th17 cells, suggesting a shared clonal origin between Th17 and Th17/1 cells in arthritis. Using CD161, a lectin-like receptor that is a marker of human Th17, we show synovial Th17 and Th17/1 cells, and unexpectedly, a large proportion of Th1 cells express CD161. We provide evidence to support a Th17 origin for Th1 cells expressing CD161. In vitro, Th17 cells that convert to a Th1 phenotype maintain CD161 expression. In the joint CD161+ Th1 cells share features with Th17 cells, with shared TCR clonality, expression of RORC2 and CCR6 and response to IL-23, although they are IL-17 negative. We propose that the Th17 phenotype may be unstable and that Th17 cells may convert to Th17/1 and Th1 cells in human arthritis. Therefore therapies targeting the induction of Th17 cells could also attenuate Th17/1 and Th1 effector populations within the inflamed joint. juvenile | CD161 | RORC2 doi/ 10.1073/pnas.1003852107

CaMKII is an abundant synaptic protein strongly implicated in plasticity. Overexpression of autonomous (T286D) CaMKII in CA1 hippocampal ceils enhances synaptic strength if T305/T306 sites are not phosphorylated, but decreases synaptic strength if they are phosphorylated. It has generally been thought that spine size and synaptic strength covary; however, the ability of CaMKII and its various phosphorylation states to control spine size has not been previously examined. Using a unique method that allows the effects of overexpressed protein to be monitored over time, we found that all autonomous forms of CaMKII increase spine size. Thus, for instance, the T286D/T305D/T306D form increases spine size but decreases synaptic strength. Further evidence for such dissociation is provided by experiments with the T286D form that has been made catalytically dead. This form fails to enhance synaptic strength but increases spine size, presumably by a structural process. Thus very different mechanisms govern how CaMKII affects spine structure and synaptic function. synaptic plasticity | structural plasticity | autophosphorylation | nonenzymatic function doi/ 10.1073/pnas.1009268107

High levels of corticosteroids (as circulate after stress) quickly and reversibly enhance hippocampal glutamatergic transmission via nongenomic actions requiring mineralocorticoid receptors. Subsequently, the hormone slowly and long-lastingly normalizes hippocampal cell function, through nuclear glucocorticoid receptors. Here we describe a rapid mineralocorticoid receptor-dependent enhancement of glutamatergic transmission in basolateral amygdala neurons. Contrary to the hippocampus, this rapid enhancement is long-lasting, potentially allowing an extended window for encoding of emotional aspects during stressful events. Importantly, the long-lasting change in state of amygdala neurons greatly affects the responsiveness to subsequent surges of corticosterone, revealing a quick suppression of glutamatergic transmission, which requires the glucocorticoid receptor. Responses of basolateral amygdala neurons to the stress hormone corticosterone can thus switch from excitatory to inhibitory, depending on the recent stress history of the organism. basolateral amygdala | glucocorticoid receptor | glutamate | miniature excitatory postsynaptic current | mineralocorticoid receptor doi/ 10.1073/pnas.0914381107

Bacillus subtilis, which grows under aerobic conditions, employs fatty acid desaturase (Des) to fluidize its membrane when subjected to temperature downshift. Des requires molecular oxygen for its activity, and its expression is regulated by DesK-DesR, a two-component system. Transcription of des is induced by the temperature downshift and is decreased when membrane fluidity is restored. B. subtilis is also capable of anaerobic growth by nitrate or nitrite respiration. We studied the mechanism of cold adaptation in B. subtilis under anaerobic conditions that were predicted to inhibit Des activity. We found that in anaerobiosis, in contrast to aerobic growth, the induction of des expression after temperature downshift (from 37[degrees]C to 25[degrees]C) was not downregulated. However, the transfer from anaerobic to aerobic conditions rapidly restored the downregulation. Under both aerobic and anaerobic conditions, the induction of des expression was substantially reduced by the addition of external fluidizing oleic acid and was fully dependent on the DesK-DesR two-component regulatory system. Fatty acid analysis proved that there was no desaturation after des induction under anaerobic conditions despite the presence of high levels of the des protein product, which was shown by immunoblot analysis. The cold adaptation of B. subtilis in anaerobiosis is therefore mediated exclusively by the increased anteiso/iso ratio of branched-chain fatty acids and not by the temporarily increased level of unsaturated fatty acids that is typical under aerobic conditions. The degrees of membrane fluidization, as measured by diphenylhexatriene fluorescence anisotropy, were found to be similar under both aerobic and anaerobic conditions. doi: 10.1128/JB.00384-10

Simple sequence repeats (SSRs) and their role in phase variation have been extensively studied in Gram-negative organisms, where they have been associated with antigenic variation and other adaptation strategies. In this study, we apply comparative genomics in order to find evidence of slipped-strand mispairing in the human Gram-positive pathogen Streptococcus agalactiae. In two consecutive screenings, 2,233 (650 + 1,583) SSRs were identified in our reference genome 2603V/R, and these loci were examined in seven other S. agalactiae genomes. A total of 56 SSR loci were found to exhibit variation, where gain or loss of repeat units was observed in at least one other genome, resulting in aberrant genotypes. Homopolymeric adenine tracts predominated among the repeats that varied. Positional analysis revealed that long polyadenine tracts were overrepresented in the 5' ends of open reading frames (ORFs) and underrepresented in the 3' ends. Repeat clustering in ORFs was also examined, and the highest degree of clustering was observed for a capsule biosynthesis gene and a pilus sortase. A statistical analysis of observed over expected ratios suggested a selective pressure against long homopolymeric tracts. Altered phenotypes were verified for three genes encoding surface-attached proteins, in which frameshifts or fusions led to truncation of proteins and/or affected surface localization through loss or gain of the cell wall sorting signal. The data suggest that SSRs contributes to genome plasticity in S. agalactiae but that the bet-hedging strategy is different from Gram-negative organisms. doi: 10.1128/JB.01465-09