89 research outputs found

    It Takes a Mouth to Eat and a Nose to Breathe: Abnormal Oral Respiration Affects Neonates' Oral Competence and Systemic Adaptation.

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    Review ArticleInternational audienceMammalian, including human, neonates are considered to be obligate nose breathers. When constrained to breathe through their mouth in response to obstructed or closed nasal passages, the effects are pervasive and profound, and sometimes last into adulthood. The present paper briefly surveys neonates' and infants' responses to this atypical mobilisation of the mouth for breathing and focuses on comparisons between human newborns and infants and the neonatal rat model. We present the effects of forced oral breathing on neonatal rats induced by experimental nasal obstruction. We assessed the multilevel consequences on physiological, structural, and behavioural variables, both during and after the obstruction episode. The effects of the compensatory mobilisation of oral resources for breathing are discussed in the light of the adaptive development of oromotor functions

    Increased ROS Production: A Component of the Longevity Equation in the Male Mygalomorph, Brachypelma albopilosa

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    The diversity of longevities encountered in wildlife is one of the most intriguing problems in biology. Evolutionary biologists have proposed different theories to explain how longevity variability may be driven by bad genes expression in late life or by gene pleiotropic effects. This reflexion has stimulated, in the last ten years, an active research on the proximal mechanisms that can shape lifespan. Reactive oxygen species (ROS), i.e., the by-products of oxidative metabolism, have emerged as the main proximate cause of ageing. Because ROS are mainly produced by the mitochondria, their production is linked to metabolic rate, and this may explain the differences in longevity between large and small species. However, their implication in the sex difference in longevity within a species has never been tested, despite the fact that these differences are widespread in the animal kingdom.Mitochondrial superoxide production of hemolymph immune cells and antioxidant and oxidative damages plasma levels were measured in adult male and female B. albopilosa at different ages. We found that female spiders are producing less mitochondrial superoxide, are better protected against oxidative attack and are then suffering less oxidative damages than males at adulthood.In tarantulas, once reaching sexual maturity, males have a life expectancy reduced to 1 to 2 years, while females can still live for 20 years, in spite of the fact that females continue to grow and moult. This study evidences an increased exposure of males to oxidative stress due to an increase in mitochondrial superoxide production and a decrease in hemolymph antioxidant defences. Such a phenomenon is likely to be part of the explanation for the sharp reduction of longevity accompanying male tarantula maturity. This opens several fundamental research roads in the future to better understand how reproduction and longevity are linked in an original ageing model

    Au fil des Araignées : les recherches actuelles

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    La receptivite sexuelle de Calliphora vomitoria (Dipteres) au cours du premier cycle gonadotrope : approches comportementale et physiologique

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    SIGLECNRS T 56543 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

    Variation des hydrocarbures cuticulaires pendant la période de gardiennage des jeune chez l'araignée, Pardosa saltans

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    International audienceLes araignées offrent une gamme étendue d’organisations sociales, différant par la complexité des interactions entre congénères ainsi que par leur durée. Cette gamme va des espèces solitaires, où les interactions entre les individus sont limitées au comportement reproducteur, jusqu’aux espèces sociales où un nombre important d’individus de tout âge coexistent au sein de sociétés permanentes. Entre ces deux extrêmes, on rencontre des formes intermédiaires d’organisation chez lesquelles la vie sociale est limitée à une période plus ou moins longue de la vie juvénile (extension temporelle du groupement mère-jeune), ou bien ne se manifeste que dans certaines conditions écologiques (agrégation d'individus adultes favorisée par l'abondance des ressources alimentaires). L'observation de la vie grégaire avec tolérance mutuelle (mère-jeunes et jeunes-jeunes) constitue actuellement une base de travail pour rechercher les facteurs capables d'inciter les jeunes à rester groupés et à se tolérer jusqu'à l'âge adulte. Notre étude sur l'évolution du groupement mère-jeunes chez une araignée vagabonde, Pardosa saltans, montre que le passage de la vie grégaire des jeunes à la vie solitaire est accompagné par un changement des profils chimiques cuticulaires et l'apparition de la prédation

    Chemical Communication and Contact Cuticular Compounds in Spiders

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    International audienceWe review here spider social contact pheromones. Spider contact pheromones are typically associated with the silk, draglines or substrate, and body cuticle. The chemical composition of the cuticle, especially the lipid layer, can be used for information transfer. These substances act as releaser pheromones and are identified by the spider after contact with another animal. Behavioural observations demonstrate that chemical contact compounds are able to inhibit aggressive behaviour between conspecifics (prevent cannibalism). Different studies have shown that qualitative and/or quantitative changes in cuticular lipids could play a role in intra- and interspecific relationships in spiders. Knowledge of the function and mode of action of cuticular compounds is only fragmentary in arachnid groups. The endocrine regulation of contact pheromone synthesis is not known

    Effects of Wolf Spiders’ Captive Environment on Their Locomotor and Exploratory Behaviours

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    International audienceHere I detail the effects of the abiotic/captive environment of an adult wandering spider, Pardosa saltans (Lycosidae) on its behaviour. These studies focused on spiders collected as adults in their natural environment and spiders developed in the laboratory under controlled conditions. Wild-caught spiders were tested either immediately after capture or after being housed for 15 days post-collection. Laboratory reared spiders were kept in different environments: small or large space combined with the presence or absence of litter. Two tests evaluated by sex show the influence of these rearing conditions: an open-field test and a radial-arm maze test. The results show that wild caught spiders of both sexes tested immediately after capture weighed significantly less and were significantly more active than spiders housed in the laboratory for 15 days and spiders reared in the laboratory. Laboratory conditions induced a positive impact on body mass and negative impact on behaviour activities. The locomotor and exploratory activities of spiders of both sexes kept in container without substrate showed lower. My results suggest that the physical enrichment of the environment can reduce these negative effects for females, but not for males that seem to be more affected by being reared under controlled conditions

    Juvenile development, ecdysteroids and hemolymph level of metabolites in the spider Brachypelma albopilosum (Theraphosidae).

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    International audienceIn the present work, juvenile development and physiological state of mygalomorph Brachypelma albopilosum were investigated by means of individual rearing under controlled conditions. Males required 4-5 years for development from first juvenile instar to adulthood, passing through 8 to 12 juvenile molts. Females developed to adults in 5-6 years with a variable juvenile molt number from 9 to 13. The development and growth of males and females took place in a similar way until the last juvenile molt leading to subadults. Ecdysteroids, total lipid, cholesterol, and protein concentrations increased along with the different development instars in both males and females. After the last juvenile molt, spiders presented morphological and biochemical sex differences. Subadult and adulthood males were smaller in size and weight than females; hemolymph levels of ecdysteroids, total lipids, cholesterol, and glucose were higher in males. These physiological and biochemical differences can be correlated to the different sexual development between males and females

    Physiological costs during maternal care in Pardosa saltans (Araneae, Lycosidae)

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    International audienceMany arachnids, like other terrestrial arthropods, provide extensive maternal care. Few studies have quantified the underlying physiological costs of maternalcare. We investigated how maternal care affects the free-moving wolf spider’s (Pardosa saltans) energy requirements. Our aim was to evaluate the contributions of protein, glucose and lipids to the maintenance of female P. saltans’ energy
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