Time domains of the hypoxic ventilatory response in ectothermic vertebrates

Over a decade has passed since Powell et al. (Respir Physiol 112:123–134, 1998) described and defined the time domains of the hypoxic ventilatory response (HVR) in adult mammals. These time domains, however, have yet to receive much attention in other vertebrate groups. The initial, acute HVR of fish, amphibians and reptiles serves to minimize the imbalance between oxygen supply and demand. If the hypoxia is sustained, a suite of secondary adjustments occur giving rise to a more long-term balance (acclimatization) that allows the behaviors of normal life. These secondary responses can change over time as a function of the nature of the stimulus (the pattern and intensity of the hypoxic exposure). To add to the complexity of this process, hypoxia can also lead to metabolic suppression (the hypoxic metabolic response) and the magnitude of this is also time dependent. Unlike the original review of Powell et al. (Respir Physiol 112:123–134, 1998) that only considered the HVR in adult animals, we also consider relevant developmental time points where information is available. Finally, in amphibians and reptiles with incompletely divided hearts the magnitude of the ventilatory response will be modulated by hypoxia-induced changes in intra-cardiac shunting that also improve the match between O2 supply and demand, and these too change in a time-dependent fashion. While the current literature on this topic is reviewed here, it is noted that this area has received little attention. We attempt to redefine time domains in a more ‘holistic’ fashion that better accommodates research on ectotherms. If we are to distinguish between the genetic, developmental and environmental influences underlying the various ventilatory responses to hypoxia, however, we must design future experiments with time domains in mind

Using landscape habitat associations to prioritize areas of conservation action for terrestrial birds

Predicting species distributions has long been a valuable tool to plan and focus efforts for biodiversity conservation, particularly because such an approach allows researchers and managers to evaluate species distribution changes in response to various threats. Utilizing data from a long-term monitoring program and land cover data sets, we modeled the probability of occupancy and colonization for 38 bird Species of Greatest Conservation Need (SGCN) in the robust design occupancy modeling framework, and used results from the best models to predict occupancy and colonization on the Iowa landscape. Bird surveys were conducted at 292 properties from April to October, 2006-2014. We calculated landscape habitat characteristics at multiple spatial scales surrounding each of our surveyed properties to be used in our models and then used kriging in ArcGIS to create predictive maps of species distributions. We validated models with data from 2013 using the area under the receiver operating characteristic curve (AUC). Probability of occupancy ranged from 0.001 (SE 0.70). The most important predictor for occupancy of grassland birds was percentage of the landscape in grassland habitat, and the most important predictor for woodland birds was percentage of the landscape in woodland habitat. This emphasizes the need for managers to restore specific habitats on the landscape. In an era during which funding continues to decrease for conservation agencies, our approach aids in determining where to focus limited resources to best conserve bird species of conservation concern

: Neurotensin and cocaine sensitization

International audienceChronic use of psychostimulants induces enduringly increased responsiveness to a subsequent psychostimulant injection and sensitivity to drug-associated cues, contributing to drug craving and relapse. Neurotensin (NT), a neuropeptide functionally linked to dopaminergic neurons, was suggested to participate in these phenomena. We and others have reported that SR 48692, an NT receptor antagonist, given in pre- or co-treatments with cocaine or amphetamine, alters some behavioral effects of these drugs in rats. However, its efficacy when applied following repeated cocaine administration remains unknown. We, therefore, evaluated the ability of SR 48692, administered after a cocaine regimen, to interfere with the expression of locomotor sensitization and conditioned place preference (CPP) in rats. We demonstrated that the expression of locomotor sensitization, induced by four cocaine injections (15 mg/kg, i.p.) every other day and a cocaine challenge 1 week later, was attenuated by a subsequent 2-week daily administration of SR 48692 (1 mg/kg, i.p.). Furthermore, the expression of cocaine-induced CPP was suppressed by a 10-day SR 48692 treatment started after the conditioning period (four 15 mg/kg cocaine injections every other day). Taken together, our data show that a chronic SR 48692 treatment given after a cocaine regimen partly reverses the expression of locomotor sensitization and CPP in the rat, suggesting that NT participates in the maintenance of these behaviors. Our results support the hypothesis that targeting neuromodulatory systems, such as the NT systems may offer new strategies in the treatment of drug addiction