Surface enlargement in the rumen of free-ranging muskoxen ( Ovibos moschatus )

The intraruminal papillation pattern indicates the degree of rumen contents stratification and is related to the feeding niche of a ruminant. Muskoxen (Ovibos moschatus) display a variety of morphophysiological adaptations typical for grazers. We investigated the intraruminal papillation of 22 free-ranging muskoxen from five different months by comparing the surface enlargement factor both between seasons and between individual rumen regions. The seasonal pattern of rumen papillation indicated a distinct seasonality in food quality. The intraruminal papillation indicated a moderate degree of rumen contents stratification typical for intermediate feeders. The nutritional ecology of muskoxen is characterised by specific morphophysiological adaptations to a grass-dominated diet that nevertheless allow extensive seasonal use of browse forag

A Comparison of digestive Tract Morphology in muskoxen and caribou from Victoria Island, Northwest Territories, Canada

Although caribou and muskoxen coexist in close proximity on southeastern Victoria Island, they appear primarily adapted to different diets and foraging strategies. Visual inspection and analysis of rumen contents for fiber and lignin from the study (unpubl.) also indicate a predominantly graminoid diet in the muskoxen and a more varied diet with a substantial browse component in the caribou.This should reduce the likelihood of competition for limited food resources in winter

Seasonal Patterns in Growth Hormone, Insulin and Insulin-like Growth Factor-1 in Female Muskoxen

Over a year, mean serum growth hormone concentrations ranged from 0.5 to 3 ng/ml in tame muskoxen with the lowest values and fewest pulses between October and January. Serum insulin ranged from 0.25 to 0.92 ng/ml, with minima in summer. There were marked seasonal changes in serum insulin-like growth factor-1 in both tame and wild muskoxen but the late summer peak was higher and more distinct in the tame animals with levels reaching 160-250 ng/ml in September

Estimates of caribou herd size using post-calving surveys in the Northwest Territories and Nunavut, Canada: A meta-analysis

Post-calving surveys to estimate herd size of barren-ground caribou (Rangifer tarandus groenlandicus, R. t. granti, and R. t. caribou) have been used for caribou herds in Alaska, Yukon, Northwest Territories, Nunavut, and Québec/Labrador. The main field procedure uses relocation of collared caribou to locate aggregated groups of hundreds or thousands of caribou during times of high insect harassment that usually occur in July. These groups are then pho­tographed to obtain a count of the caribou in the aggregated groups. Often some caribou are missed, and the count of caribou may be a negatively biased estimate of total herd size, unless a high proportion of the herd is found and photographed. To address this, some previous studies have used the Lincoln-Petersen estimator, which estimates the proportion of the herd counted based on the percentage of available collared caribou found during the survey. However, this estimator assumes equal probabilities of all groups of caribou being found, regardless of group size and the numbers of collared caribou in the group. These assumptions may not be valid, as larger groups are more likely to be found than smaller groups, particularly if there are several collared caribou present. This may lead to estimates that are biased low, along with an estimate of variance that may also be biased low. A two phase estimator developed by Rivest et al., in 1998 became available in R statistical software in 2012. We analyzed 20 data sets from post-calving surveys in the NWT and NU carried out between 2000 and 2015 using the Rivest estimator to explore working characteristics of this estimator. We compared the Rivest estimates with Lincoln-Petersen estimates and total counts on each survey. We considered factors that influence precision of the Rivest estimator with a focus on sampling factors such as the proportion of collars found, the number of collars available, and natural factors such as the degree of aggregation of caribou in each survey (as indexed by the negative binomial dispersion parameter). In general, the Rivest estimator displayed acceptable preci­sion when high proportions of caribou groups with collars were detected and counted, collar numbers were sufficient, and aggregation was adequate. Notable exceptions occurred in years of lower aggregation which resulted in many small groups with 0 or few collared caribou, and in these cases herd estimates had large variances and low precision. Estimates from the Rivest estimator, Lincoln-Petersen estimator, and total counts converged when sampling effort was high, collar numbers relative to herd size were high, and caribou were well aggregated in a limited number of groups. In other cases, estimates of the Rivest estimator were generally higher than Lincoln-Petersen estimates, presumably due to negative bias with the Lincoln-Petersen estimator. We provide a set of working recommendations to optimize field sampling to ensure reliable estimates of herd size using post-calving methods

Genetic diversity, structure and gene flow of migratory barren-ground caribou (Rangifer tarandus groenlandicus) in Canada

Migratory barren-ground caribou (Rangifer tarandus groenlandicus) provide an opportunity to examine the genetic population structure of a migratory large mammal whose movements and distribution, in some instances, have not been heavily influenced by human activities that result in habitat loss or fragmentation. These caribou have likely reached large effective population sizes since their rapid radiation during the early Holocene despite cyclic changes in abundance. Migratory barren-ground caribou are managed as discrete subpopulations. We investigated genetic variation among those subpopulations to determine the patterns of genetic diversity within and among them, and the implications for long-term persistence of caribou. We identified three distinct genetic clusters across the Canadian arctic tundra: the first cluster consisted of all fully-continental migratory barren-ground subpopulations; the second cluster was the Dolphin and Union caribou; and the third cluster was caribou from Southampton Island. The Southampton Island caribou are especially genetically distinct from the other barren-ground type caribou. Gene flow among subpopulations varied across the range. Occasional gene flow across the sea-ice is likely the reason for high levels of genetic variation in the Dolphin and Union subpopulation, which experienced very low numbers in the past. These results suggest that for most migratory caribou subpopulations, connectivity among subpopulations plays an important role in maintaining natural genetic diversity. Our analyses provide insight into the levels of microsatellite genetic diversity and patterns of gene flow that may be common to large subpopulations that historically had a continuous distribution across a large continental range. These data can also be used as a benchmark to compare the effects of habitat fragmentation and bottlenecks on other large caribou populations

Effect of L-thyroxine treatment on peripheral blood dendritic cell subpopulations in patients with Hashimoto’s thyroiditis

Recent reports suggested dendritic cells (DCs) to be important players in the pathogenesis of autoimmune thyroid processes in humans. However, there are virtually no data addressing the influence of thyroid autoaggression-associated disturbances of thyrometabolic conditions on DCs biology. The aim of the study was to evaluate the influence of L-thyroxine supplementation on conventional and plasmacytoid peripheral blood DCs subtypes in patients with hypothyroidism due to Hashimoto’s thyroiditis (HT). Eighteen patients with newly diagnosed hypothyroidism due to HT were included into the study. All patients received L-thyroxine treatment with doses adjusted to reach euthyroidism. Peripheral blood DC subtypes structure and immunoregulatory phenotype were analyzed by flow cytometry in the same patient prospectively at two time points: (i) beforeand (ii) 3 months after beginning of L-thyroxine treatment (hypothyroidism vs. euthyroidism, respectively). Percentage of plasmacytoid DCs in peripheral blood mononuclear cells fraction was significantly decreased in the course of L-thyroxine treatment (0.27 ± 0.19 vs. 0.11 ± 0.08; p < 0.05), whereas we did not observe any changes in the number of conventional DCs. However, the phenotypic analysis showed a significant increase of conventional DCs expressing CD86 and CD91 (64.25 ± 21.6% vs. 86.3 ± 11%; p < 0.05 and 30.75 ± 11.66% vs. 44.5 ± 13.3%; p < 0.05; respectively) in euthyroid patients. Standard L-thyroxine supplementation in HT patients exerted significant immunoregulatory effects, associated with quantitative and phenotypic changes of peripheral blood DC subpopulations