Search results for "MESH : Adaptation"
showing 5 items of 5 documents
Survival cost of an early immune soliciting in nature.
2009
8 pages; International audience; If immune functions confer obvious benefits to hosts, life-history theory assumes that they also induce costs, leading to trade-offs between immunity and other fitness components. However, whether substantial fitness costs are associated with immune systems in the wild is debatable, as numerous factors may influence the costs and benefits associated with immune activation. Here, we explore the survival cost of immune deployment in postfledging birds. We injected Eurasian collared dove nestlings (Streptopelia decaocto) with antigens from Escherichia coli, and examined whether this immune challenge affected survival after fledging. To assess survival, birds we…
Strength training in old age: adaptation of antagonist muscles at the ankle joint.
2005
The purpose of this study was to determine whether strength training could reduce the deficit in plantarflexion (PF) maximal voluntary contraction (MVC) torque observed in previous studies in older subjects relative to young adults. Accordingly, the effects of a 6-month strength training program on the muscle and neural properties of the major muscle groups around the ankle were examined. PF and dorsiflexion (DF) isometric MVC torques were measured and surface electromyographic activity of the triceps surae and tibialis anterior muscles was recorded. The strength training program was very effective in improving strength in PF (+24.5%), and it thus reduced the DF-to-PF MVC torque ratio; in a…
Food Intake Adaptation to Dietary Fat Involves PSA-Dependent Rewiring of the Arcuate Melanocortin System in Mice
2012
International audience; Hormones such as leptin and ghrelin can rapidly rewire hypothalamic feeding circuits when injected into rodent brains. These experimental manipulations suggest that the hypothalamus might reorganize continually in adulthood to integrate the metabolic status of the whole body. In this study, we examined whether hypothalamic plasticity occurs in naive animals according to their nutritional conditions. For this purpose, we fed mice with a short-term high-fat diet (HFD) and assessed brain remodeling through its molecular and functional signature. We found that HFD for 3 d rewired the hypothalamic arcuate nucleus, increasing the anorexigenic tone due to activated pro-opio…
Arabidopsis thaliana nicotianamine synthase 4 is required for proper response to iron deficiency and to cadmium exposure.
2013
International audience; The nicotianamine synthase (NAS) enzymes catalyze the formation of nicotianamine (NA), a non-proteinogenic amino acid involved in iron homeostasis. We undertook the functional characterization of AtNAS4, the fourth member of the Arabidopsis thaliana NAS gene family. A mutant carrying a T-DNA insertion in AtNAS4 (atnas4), as well as lines overexpressing AtNAS4 both in the atnas4 and the wild-type genetic backgrounds, were used to decipher the role of AtNAS4 in NA synthesis, iron homeostasis and the plant response to iron deficiency or cadmium supply. We showed that AtNAS4 is an important source for NA. Whereas atnas4 had normal growth in iron-sufficient medium, it dis…
Modification of hosts' behavior by a parasite: field evidence for adaptive manipulation.
2007
9 pages; International audience; Parasites relying on trophic transmission to complete their life cycles often induce modifications of their host's behavior in ways that may increase their susceptibility to predation by final hosts. These modifications have often been interpreted as parasite adaptations, but very few studies have demonstrated that host manipulation has fitness benefits for the parasite. The aim of the present study was to address the adaptive significance of parasite manipulation by coupling observations of behavioral manipulation to estimates of trophic transmission to the definitive host in the natural environment. We show that the acanthocephalan parasite Pomphorhynchus …