Post-hatching parental care behaviour and hormonal status in a precocial bird

In birds, the link between parental care behaviour and prolactin release during incubation persists after hatching in altricial birds, but has never been precisely studied during the whole rearing period in precocial species, such as ducks. The present study aims to understand how changes in parental care after hatching are related to circulating prolactin levels in mallard hens rearing ducklings. Blood was sampled in hens over at least 13 post-hatching weeks and the behaviour of the hens and the ducklings was recorded daily until fledging. Contacts between hens and the ducklings, leadership of the ducklings and gathering of them steadily decreased over post-hatching time. Conversely, resting, preening and agonistic behaviour of hens towards ducklings increased. Plasma prolactin concentrations remained at high levels after hatching and then fell after week 6 when body mass and structural size of the young were close to those of the hen. Parental care behaviour declined linearly with brood age, showed a disruption of the hen-brood bond at week 6 post-hatching and was related to prolactin concentration according to a sigmoid function. Our results suggest that a definite threshold in circulating prolactin is necessary to promote and/or to maintain post-hatching parental care in ducks.     

The effect of n-3 PUFA on eNOS activity and expression in Ea hy 926 cells

The aim of this study was to evaluate the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on NO synthase (eNOS) activation in Ea hy 926 endothelial cells. EPA or DHA (0-80 microM), added to the culture medium during 24h, were dose-dependently incorporated into the cells. In control medium, eNOS activity (evaluated by the citrulline assay) and eNOS phosphorylation on Ser 1177 were correlated. They were increased by 10 microM histamine and prevented by 20 microM lysophosphatidylcholine (LPC). By contrast, EPA or DHA increased basal phosphorylation without affecting eNOS activity in non-stimulated cells, but dose-dependently decreased this activity in histamine-stimulated cells without modifying the phosphorylation level. Furthermore, EPA and DHA did not prevent the deleterious effects of LPC on histamine stimulation. In conclusion, incorporation of EPA and DHA could be deleterious for endothelial cells by deregulating the activation of eNOS and preventing NO liberation.     

Contribution of toxins to the pathogenesis of inhalational anthrax

Inhalational anthrax is a life-threatening infectious disease of considerable concern, especially as a potential bioterrorism agent. Progress is gradually being made towards understanding the mechanisms used by Bacillus anthracis to escape the immune system and to induce severe septicaemia associated with toxaemia and leading to death. Recent advances in fundamental research have revealed previously unsuspected roles for toxins in various cell types. We summarize here pathological data for animal models and macroscopic histological examination data from recent clinical records, which we link to the effects of toxins. We describe three major steps in infection: (i) an invasion phase in the lung, during which toxins have short-distance effects on lung phagocytes; (ii) a phase of bacillus proliferation in the mediastinal lymph nodes, with local effects of toxins; and (iii) a terminal, diffusion phase, characterized by a high blood bacterial load and by long-distance effects of toxins, leading to host death. The pathophysiology of inhalational anthrax thus involves interactions between toxins and various cell partners, throughout the course of infection.     

A novel mode of bathing behavior of hummingbirds recorded in the Brazilian ruby Heliodoxa rubricauda and allies (Aves: Trochilidae)

acta ethologica - The Brazilian ruby, Heliodoxa rubricauda, is a forest species of hummingbird endemic to the Atlantic Forest. It belongs to an Andean clade of birds with robust and strong legs and...     

Assessing overfishing based on the distance-to-target approach

The International Journal of Life Cycle Assessment - Overfishing has been a global challenge for several decades with severe impacts on biodiversity and ecosystem services. Several approaches for...     

Modifications of cell wall pectin in tomato cell suspension in response to cadmium and zinc

Retention of metal cations by the cell wall is a common process found in plants in response to stress induced by the presence of trace metals (TMs). In this study conducted on a tomato cell suspension culture, cadmium (Cd) and zinc (Zn) were added to the medium at maximal concentrations of 0.5 and 2 mM, respectively. We showed that around 50 % of Zn or Cd was confined into the cell wall of tomato cells. Besides, their accumulation in the cell wall increased with the exogenous concentration in the culture medium. Characterization of cell wall pectins showed a decrease in the highly methylesterified pectin fraction whereas the weakly methylesterified pectin remained stable in response to Cd. Moreover, a significant increase in the degree of methylesterification was observed in both fractions. This was probably associated to the reduced pectin methylesterase (PME) activity in the treated cells. Furthermore, linked to a reduction of pectin content we showed a reduced expression of the galacturonosyltransferase QUA1 gene whereas PME1 expression remained unchanged. Taking together, these data strongly suggest that pectin biosynthesis and its modification in the cell wall are strongly regulated in response to TM exposure in tomato cells.     

Using basic plant traits to predict ungulate seed dispersal potential

Habitat fragmentation contributes to the decline of plant species by decreasing gene flow among populations. Restoring connectivity among habitat patches is therefore a major issue for plant conservation. However, deciding where to focus restoration efforts requires identifying suitable dispersers for each target plant species. We collected data from the literature on wild and domesticated ungulates, known to be effective seed dispersers, and on the plants they dispersed in Europe via epi‐ and/or endozoochory. We performed a systematic literature review to identify plant and animal traits relevant for seed dispersal. We first modeled the relationships between epi‐ or endozoochory and a priori selected plant traits (diaspore releasing height, length, shape and morphology, and habitat openness). The differences we underlined between the two dispersal mechanisms justified splitting our analyses accordingly. Then, for each dispersal mechanism, we asked whether basic plant traits could be used to predict specific traits of ungulates as endozoochorous or epizoochorous seed dispersers. We modeled the relationships between a priori selected ungulate traits for epizoochory (habitat openness, shoulder height, hair curliness, and hair length) and for endozoochory (habitat openness, body mass, feeding type and digestive system) and plant traits. Plant habitat openness and diaspore morphology were the predictors that most often explained differences among ungulates for epizoochory, whereas plant habitat openness and diaspore releasing height most often explained differences for endozoochory. Our trait‐based predictive models can help improve our ability to propose more precise management decisions for the conservation of plant populations worldwide by taking into account ungulate dispersers.