Mosher B.P.,University of Alaska Fairbanks |
Taylor B.E.,University of Alaska Fairbanks |
Taylor B.E.,Institute of Arctic Biology |
Harris M.B.,University of Alaska Fairbanks |
Harris M.B.,Institute of Arctic Biology
Respiratory Physiology and Neurobiology
Serotonergic dysfunction compromises ventilatory chemosensitivity and may enhance vulnerability to pathologies such as the Sudden Infant Death Syndrome (SIDS). We have shown raphé contributions to central chemosensitivity involving serotonin (5-HT)-and γ-aminobutyric acid (GABA)-mediated mechanisms. We tested the hypothesis that mild intermittent hypercapnia (IHc) induces respiratory plasticity, due in part to strengthening of GABA mechanisms. Rat pups were IHc-pretreated (eight consecutive cycles; 5min 5% CO2 - air, 10min air) or constant normocapnia-pretreated as a control, each day for 5 consecutive days beginning at P12. We subsequently assessed CO2 responsiveness using the in situ perfused brainstem preparation. Hypercapnic responses were determined with and without pharmacological manipulation. Results show IHc-pretreatment induces plasticity sufficient for responsiveness despite removal of otherwise critical ketanserin-sensitive mechanisms. Responsiveness following IHc-pretreatment was absent if ketanserin was combined with GABAergic antagonism, indicating that plasticity depends on GABAergic mechanisms. We propose that IHc-induced plasticity could reduce the severity of reflex dysfunctions underlying pathologies such as SIDS. © 2014 Elsevier B.V. Source
Post E.,Pennsylvania State University |
Bhatt U.S.,University of Alaska Fairbanks |
Bitz C.M.,University of Washington |
Brodie J.F.,University of British Columbia |
And 8 more authors.
After a decade with nine of the lowest arctic sea-ice minima on record, including the historically low minimum in 2012, we synthesize recent developments in the study of ecological responses to sea-ice decline. Sea-ice loss emerges as an important driver of marine and terrestrial ecological dynamics, influencing productivity, species interactions, population mixing, gene flow, and pathogen and disease transmission. Major challenges in the near future include assigning clearer attribution to sea ice as a primary driver of such dynamics, especially in terrestrial systems, and addressing pressures arising from human use of arctic coastal and near-shore areas as sea ice diminishes. Source
Stimmelmayr R.,University of Trinidad and Tobago |
Stimmelmayr R.,Institute of Arctic Biology |
Stefani L.M.,Santa Catarina State University |
Thrall M.A.,University of Trinidad and Tobago |
And 6 more authors.
We report the first documented occurrence of an outbreak of trichomonosis in a free-ranging small flock of Eurasian collared doves (Streptopelia decaocto) and African collared dove hybrids (Streptopelia risoria) in the Caribbean. In total, 18 birds were examined, including six African collared dove × Eurasian collared dove hybrids and 12 Eurasian collared doves. The affected age class consisted of adults. Sex distribution was equal. With a flock population size of 200 birds, mortality rate for the outbreak was estimated at 1520. Living birds were weak, showing evidence of mucus-stained beaks and open-mouth breathing. Caseous ulcerative yellow lesions were restricted to the upper gastrointestinal tract, with the exception of one bird, which had lesions in the upper gastrointestinal tract and in the liver. Ninety-four percent (17/18) of the affected birds had multiple extensive lesions. Lesions located on the roof of the oral cavity extended in 33 (6/18) into the orbit and in 11 (2/18) into the braincase. Using wet-mount microscopy, we were able to confirm Trichomonas gallinae in 22 (4/18) of the sampled animals. Fifteen samples submitted for PCR analysis tested positive. Sequence analysis of the internal transcribed spacer 1 (ITS-1) region of the ribosomal RNA (rRNA) revealed two distinct genotypes of Trichomonas. One sequence had 100 identity to the prototype T. gallinae isolate, whereas the other sequences had 98100 identity to recently described Trichomonas-like parabasalid. On the basis of gross and histologic findings, along with the sequence results from the columbids in this report, it is likely that this Trichomonas-like parabasalid is pathogenic. © American Association of Avian Pathologists. Source
Nash S.H.,Institute of Arctic Biology |
Nash S.H.,University of Alaska Fairbanks |
Nash S.H.,U.S. National Cancer Institute |
Kristal A.R.,Fred Hutchinson Cancer Research Center |
And 5 more authors.
Journal of Nutrition
Objectively measured biomarkers will help to resolve the controversial role of sugar intake in the etiology of obesity and related chronic diseases. We recently validated a dual-isotope model based on RBC carbon (δ13C) and nitrogen (δ15N) isotope ratios that explained a large percentage of the variation in self-reported sugar intake in a Yup'ik study population. Stable isotope ratios can easily be measured from many tissues, including RBCs, plasma, and hair; however, it is not known how is otopic models of sugar intake compare among these tissues. Here, we compared self-reported sugar intake with models based on RBCs, plasma, and hair δ13C and δ15N in Yup'ik people. We also evaluated associations of sugar intake with fasting plasma glucose d13C. Finally, we evaluated relations between δ13C and δ15N values in hair, plasma, RBCs, and fasting plasma glucose to allow comparison of isotope ratios across tissue types.Models using RBCs, plasma, or hair isotope ratios explained similar amounts of variance in total sugar, added sugar, and sugar-sweetened beverage intake (~53%, 48%, and 34%, respectively); however, the association with δ13C was strongest for models based on RBCs and hair. There were no associations with fasting plasma glucose δ13C (R2 = 0.03). The δ13C and δ15N values of RBCs, plasma, and hair showed strong, positive correlations; the slopes of these relations did not differ from 1. This study demonstrates that RBC, plasma, and hair isotope ratios predict sugar intake and provides data that will allow comparison of studies using different sample types. ©2014 American Society for Nutrition. Source
Sheriff M.J.,Institute of Arctic Biology |
Kenagy G.J.,University of Washington |
Richter M.,University of Alaska Fairbanks |
Richter M.,University of Alaska Anchorage |
And 6 more authors.
Proceedings of the Royal Society B: Biological Sciences
Ecologists need an empirical understanding of physiological and behavioural adjustments that animals can make in response to seasonal and long-term variations in environmental conditions. Because many species experience trade-offs between timing and duration of one seasonal event versus another and because interacting species may also shift phenologies at different rates, it is possible that, in aggregate, phenological shifts could result in mismatches that disrupt ecological communities. We investigated the timing of seasonal events over 14 years in two Arctic ground squirrel populations living 20 km apart in Northern Alaska. At Atigun River, snow melt occurred 27 days earlier and snow cover began 17 days later than at Toolik Lake. This spatial differential was reflected in significant variation in the timing of most seasonal events in ground squirrels living at the two sites. Although reproductive males ended seasonal torpor on the same date at both sites, Atigun males emerged from hibernation 9 days earlier and entered hibernation 5 days later than Toolik males. Atigun females emerged and bred 13 days earlier and entered hibernation 9 days earlier than those at Toolik. We propose that this variation in phenology over a small spatial scale is likely generated by plasticity of physiological mechanisms that may also provide individuals the ability to respond to variation in environmental conditions over time. © 2010 The Royal Society. Source