Tree diversity and species identity effects on soil fungi, protists and animals are context dependent

Plant species richness and the presence of certain influential species (sampling effect) drive the stability and functionality of ecosystems as well as primary production and biomass of consumers. However, little is known about these floristic effects on richness and community composition of soil biota in forest habitats owing to methodological constraints. We developed a DNA metabarcoding approach to identify the major eukaryote groups directly from soil with roughly species-level resolution. Using this method, we examined the effects of tree diversity and individual tree species on soil microbial biomass and taxonomic richness of soil biota in two experimental study systems in Finland and Estonia and accounted for edaphic variables and spatial autocorrelation. Our analyses revealed that the effects of tree diversity and individual species on soil biota are largely context dependent. Multiple regression and structural equation modelling suggested that biomass, soil pH, nutrients and tree species directly affect richness of different taxonomic groups. The community composition of most soil organisms was strongly correlated due to similar response to environmental predictors rather than causal relationships. On a local scale, soil resources and tree species have stronger effect on diversity of soil biota than tree species richness per se

Maternal and fetal endocrine stress response at vaginal delivery with and without an epidural block

Peer Reviewe

Actions of enflurane, isoflurane, vecuronium, atracurium, and pancuronium on pulmonary resistance in dogs.

peer reviewedThe effects of enflurane, isoflurane, vecuronium, atracurium, and pancuronium on pulmonary resistance and heart rate were studied in 30 vagotomized dogs lying supine and anesthetized with chloralose-urethane. None of the five drugs affected pulmonary resistance when the airway was unstimulated. Enflurane and isoflurane significantly attenuated the increase in pulmonary resistance induced by electrical stimulation of the vagus nerves. This effect was dose-dependent and similar for both anesthetics at equivalent multiples of their minimum alveolar concentration. Atracurium significantly (P less than 0.05) enhanced the increase in pulmonary resistance induced by vagus nerve stimulation; vecuronium had no significant effect. Pancuronium, up to a cumulative dose of 0.14 mg/kg, also significantly (P less than 0.05) enhanced the increase in pulmonary resistance induced by vagus nerve stimulation; but this effect was reversed by further increasing the dose. Pancuronium also attenuated the cardiodecelerator response to vagus nerve stimulation in a dose-dependent fashion. The underlying mechanisms for the attenuation of responses to vagus nerve stimulation by enflurane or isoflurane or for the increase in response with atracurium are unknown. Pancuronium at lower doses increases the response most likely by blocking prejunctional muscarinic receptors (M2) that physiologically inhibit vagally mediated increases in pulmonary resistance

Effects of neuromuscular blocking agents on central respiratory chemosensitivity in newborn rats

Neuromuscular blocking agents suppress central respiratory activity through their inhibitory effects on preinspiratory neurons and the synaptic drive from preinspiratory neurons to inspiratory neurons. Central CO2-chemosensitive areas, which partly consist of CO2-excited neurons, in the rostral ventrolateral medulla are thought to provide tonic drive to the central respiratory network and involve cholinergic mechanisms, which led us to hypothesize that neuromuscular blocking agents can inhibit CO2-excited neurons and attenuate respiratory CO2 responsiveness. To test this hypothesis, we used isolated brainstem-spinal cord preparations from newborn rats. The increase of C4 burst frequency induced by a hypercapnic superfusate, i.e. respiratory CO2 responsiveness, was suppressed by the application of neuromuscular blocking agents, either d-tubocurarine (10, 100μM) or vecuronium (100μM). These agents (40μM) also induced hyperpolarization and decreases in firing frequency of CO2-excited neurons in the rostral ventrolateral medulla. Our results demonstrate that neuromuscular blocking agents inhibit CO2-excited tonic firing neurons and attenuate respiratory CO2 responsiveness