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Single Compartment (single + compartment)
Selected AbstractsBioenergetic and pharmacokinetic model for exposure of common loon (Gavia Immer) chicks to methylmercuryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2007William H. Karasov Abstract A bioenergetics model was used to predict food intake of common loon (Gavia immer) chicks as a function of body mass during development, and a pharmacokinetics model, based on first-order kinetics in a single compartment, was used to predict blood Hg level as a function of food intake rate, food Hg content, body mass, and Hg absorption and elimination. Predictions were tested in captive growing chicks fed trout (Salmo gairdneri) with average MeHg concentrations of 0.02 (control), 0.4, and 1.2 ,g/g wet mass (delivered as CH3HgCl). Predicted food intake matched observed intake through 50 d of age but then exceeded observed intake by an amount that grew progressively larger with age, reaching a significant overestimate of 28% by the end of the trial. Respiration in older, nongrowing birds probably was overestimated by using rates measured in younger, growing birds. Close agreement was found between simulations and measured blood Hg, which varied significantly with dietary Hg and age. Although chicks may hatch with different blood Hg levels, their blood level is determined mainly by dietary Hg level beyond approximately two weeks of age. The model also may be useful for predicting Hg levels in adults and in the eggs that they lay, but its accuracy in both chicks and adults needs to be tested in free-living birds. [source] Achromatic Plumage Reflectance, Social Dominance and Female Mate Preference in Black-Capped Chickadees (Poecile atricapillus)ETHOLOGY, Issue 10 2005Elisabeth A. Woodcock Individual variation in achromatic plumage reflectance of male Black-capped Chickadees (Poecile atricapillus) is correlated with social rank and reproductive success, suggesting it may play an important role in sexual signaling. We asked whether female chickadees could assess male quality based on plumage, in the absence of information about relative social dominance. Sexually mature but inexperienced females captured during the pair formation period in late fall and early winter were presented with a choice of two unfamiliar, sexually experienced males in separate compartments of an outdoor mate choice arena. Following each preference trial, we released the males into a single compartment and scored their pairwise dominance interactions. In 10 of 11 trials, females spent significantly more time with the male subsequently identified as dominant, despite not witnessing the males interact. Spectral analysis of male plumage reflectance revealed that UV-chroma of dark body regions (bib, cap and mantle) was significantly greater in dominant, preferred males and that dominant, preferred males had significantly brighter white cheek patches. There were no differences in vocalization rates of preferred and non-preferred males. These results show that female chickadees can rapidly assess unfamiliar males based on visual cues, and suggest that variation in achromatic plumage functions in sexual signaling. [source] Solid emulsion gel as a vehicle for delivery of polyunsaturated fatty acids: implications for tissue repair, dermal angiogenesis and wound healingJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 7 2008Kirill I. Shingel Abstract The paper describes preparation and biological characterization of the solid hybrid biomaterial that was designed for cell-targeted lipid delivery in healing tissues. The material referred to as ,solid emulsion gel' combines a protein-stabilized lipid emulsion and a hydrogel structure in a single compartment. The potential of the omega-3 (n-3)-fatty acids rich solid emulsion gel for tissue repair applications was investigated at the macro-, micro-, molecular and gene expression levels, using human fibroblasts and endothelial cells and a porcine model of full-thickness wounds. Being non-cytotoxic in vitro and in vivo, the biomaterial was found to affect cell metabolism, modulate expression of certain genes, stimulate early angiogenesis and promote wound repair in vivo. The neovascular response in vivo was correlated with upregulated expression of the genes involved in lipid transport (e.g. adipophilin), anti-apoptosis (e.g. heat shock proteins, haem oxygenase 1) and angiogenesis (vascular endothelial growth factor, placental growth factor). Collectively, the results of this study provide first evidence that the angiogenic response provided by solid emulsion gel-mediated delivery of n-3 fatty acids is an alternative to the topical administration of exogenous growth factors or gene therapy, and can be advantageously used for the stimulation of tissue repair in complex wounds. Copyright © 2008 John Wiley & Sons, Ltd. [source] A model of thalamocortical relay cellsTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Paul A. Rhodes It is well established that the main intrinsic electrophysiological properties of thalamocortical relay cells, production of a low threshold burst upon release from hyperpolarized potential and production of a train of single spikes following stimulation from depolarized potentials, can be readily modelled using a single compartment. There is, however, another less well explored intrinsic electrophysiological characteristic of relay cells for which models have not yet accounted: at somatic potentials near spike threshold, relay cells produce a fast ragged high threshold oscillation in somatic voltage. Optical [Ca2+] imaging and pharmacological tests indicate that this oscillation correlates with a high threshold Ca2+ current in the dendrites. Here we present the development of a new compartment model of the thalamic relay cell guided by the simultaneous constraints that it must produce the familiar regular spiking relay mode and low threshold rebound bursts which characterize these cells, as well as the less-studied fast oscillation occurring at near-threshold somatic potentials. We arrive at a model cell which is capable of the production of isolated high threshold Ca2+ spikes in distal branch segments, driven by a rapidly inactivating intermediate threshold Ca2+ channel. Further, the model produces the low threshold spike behaviour of the relay cell without requiring high T-current density in the distal dendritic segments. The results thus support a new picture of the dendritic tree of relay cells which may have implications for the manner in which thalamic relay cells integrate descending input from the cortex. [source] Increased spawning activity of female Nile tilapia (Oreochromis niloticus) (L.) after stocking density and photoperiod manipulationAQUACULTURE RESEARCH, Issue 10 2010Boris Adrien De Lapeyre Abstract This study was conducted to evaluate the effects of stocking density and photoperiod in increasing the reproductive performance of Oreochromis niloticus. In experiment 1, a change in stocking density (from 47.7 to 6.8 kg m,3) was performed, with groups of 48 females moved to single compartments. In experiment 2, 36 females experienced a 6L:18D photoperiod for 21 or 28 days (stocking density: 31.3 kg m,3) before being placed in individual compartments (stocking density of 6.9 kg m,3, 12L:12D photoperiod). The spawning rates in experiment 1 (32.2%) and in experiment 2 (21 days: 65.2%, 28 days: 36.1%) were significantly higher than those in the control (17.7%). On the other hand, hatching and swim-up fry rates were significantly lower in experiment 2 , 21 days (41.3%, 40.4%) but not in experiment 1 (64.0%, 56.3%) compared with the control (67.0%, 62.3%). The spawning rate in experiment 2 , 21-day treatment group was the highest, while the number of eggs collected per female was significantly lower than that in the control. In experiments 1 (20.8%) and 2 (21 days: 44.4%, 28 days: 19.4%), the daily spawning rates were the highest 3 days after maintaining females in single compartments. The current experiment demonstrates how specific stocking density changes can be used to induce higher spawning rates in Nile tilapia. [source] | ||||||||||