An arctic breeding songbird overheats during intense activity even at low air temperatures.

Birds maintain some of the highest body temperatures among endothermic animals. Often deemed a selective advantage for heat tolerance, high body temperatures also limits birds' thermal safety margin before reaching lethal levels. Recent modelling suggests that sustained effort in Arctic birds might be restricted at mild air temperatures, which may require reductions in activity to avoid overheating, with expected negative impacts on reproductive performance.

Vegetation biomass and topography are associated with seasonal habitat selection and fall translocation behavior in Arctic hares.

Habitat selection theory suggests that environmental features selected at coarse scales reveal fundamental factors affecting animal fitness. When these factors vary across seasons, they may lead to large-scale movements, including long-distance seasonal migrations. We analyzed the seasonal habitat selection of 25 satellite-tracked Arctic hares from a population on Ellesmere Island (Nunavut, Canada) that relocated over 100 km in the fall.

Apelin stimulation of the vascular skeletal muscle stem cell niche enhances endogenous repair in dystrophic mice.

Impaired skeletal muscle stem cell (MuSC) function has long been suspected to contribute to the pathogenesis of muscular dystrophy (MD). Here, we showed that defects in the endothelial cell (EC) compartment of the vascular stem cell niche in mouse models of Duchenne MD, laminin α2-related MD, and collagen VI-related myopathy were associated with inefficient mobilization of MuSCs after tissue damage. Using chemoinformatic analysis, we identified the 13-amino acid form of the peptide hormone apelin (AP-13) as a candidate for systemic stimulation of skeletal muscle ECs.

Under pressure-exploring partner changes, physiological responses and telomere dynamics in northern gannets across varying breeding conditions.

Background: Life history theory predicts trade-offs between reproduction and survival in species like the northern gannet (). During breeding, demanding foraging conditions lead them to expand their foraging range and diversify their diet, increasing the risk of reproductive failure. Changing partners may enhance breeding success but lead to more physiological costs.

Estimated diameter increase from a 4S to a 6S hamstring graft configuration - A cadaveric study.

Purpose: Graft diameter in anterior cruciate ligament reconstructions has been shown to influence the risk of failure. It is therefore important to be able to adjust the graft configuration to modify the diameter. To measure the impact of a 6-strand (6S) hamstring autograft configuration on graft diameter compared to the standard 4-strand (4S) configuration.

Born in the cold: contrasted thermal exchanges and maintenance costs in juvenile and adult snow buntings on their breeding and wintering grounds.

Several species of passerines leave their nest with unfinished feather growth, resulting in lower feather insulation and increased thermoregulatory demands compared to adults. However, feather insulation is essential for avian species breeding at northern latitudes, where cold conditions or even snowstorms can occur during the breeding season. In altricial arctic species, increased heat loss caused by poor feather insulation during growth could be counter-adaptative as it creates additional energy demands for thermoregulation.

Evidence for a maintenance cost for birds maintaining highly flexible basal, but not summit, metabolic rates.

Reversible phenotypic flexibility allows organisms to better match phenotypes to prevailing environmental conditions and may produce fitness benefits. Costs and constraints of phenotypic flexibility may limit the capacity for flexible responses but are not well understood nor documented. Costs could include expenses associated with maintaining the flexible system or with generating the flexible response.

A Partial-Thickness Quadriceps Autograft Reliably Augments the Size of the Hamstring Graft During Anterior Cruciate Ligament Reconstruction.

Purpose: To measure the increase in diameter resulting from the augmentation of a hamstring autograft with a partial width rectus femoris tendon band in anterior cruciate ligament reconstruction.

Methods: Thirty-three cadaveric knees were dissected to harvest semitendinosus and gracilis tendons (4S) along with a 6-mm wide tendon band from the rectus femoris. Harvesting was done according to the usual surgical techniques of both harvests.

How does mitochondrial function relate to thermogenic capacity and basal metabolic rate in small birds?

We investigated the role of mitochondrial function in the avian thermoregulatory response to a cold environment. Using black-capped chickadees (Poecile atricapillus) acclimated to cold (-10°C) and thermoneutral (27°C) temperatures, we expected to observe an upregulation of pectoralis muscle and liver respiratory capacity that would be visible in mitochondrial adjustments in cold-acclimated birds. We also predicted that these adjustments would correlate with thermogenic capacity (Msum) and basal metabolic rate (BMR).

Anterior Cruciate Ligament Sizing Tools Can Be Interchanged Without Affecting Graft Diameter Measurement.

Purpose: To determine whether different types of measurement tools can be interchanged without significantly affecting the resulting graft diameter.

Methods: Hamstrings (gracilis and semitendinosus) and quadriceps tendons in 33 cadaver knees were harvested. Three different anterior cruciate ligament (ACL) graft combinations were created using these tendons, making 99 cadaver grafts samples available to measure.

Long-distance, synchronized and directional fall movements suggest migration in Arctic hares on Ellesmere Island (Canada).

Animal migration contributes largely to the seasonal dynamics of High Arctic ecosystems, linking distant habitats and impacting ecosystem structure and function. In polar deserts, Arctic hares are abundant herbivores and important components of food webs. Their annual migrations have long been suspected, but never confirmed.

Early life neonicotinoid exposure results in proximal benefits and ultimate carryover effects.

Neonicotinoids are insecticides widely used as seed treatments that appear to have multiple negative effects on birds at a diversity of biological scales. Adult birds exposed to a low dose of imidacloprid, one of the most commonly used neonicotinoids, presented reduced fat stores, delayed migration and potentially altered orientation. However, little is known on the effect of imidacloprid on birds growth rate despite studies that have documented disruptive effects of low imidacloprid doses on thyroid gland communication.

Limited heat tolerance in a cold-adapted seabird: implications of a warming Arctic.

The Arctic is warming at approximately twice the global rate, with well-documented indirect effects on wildlife. However, few studies have examined the direct effects of warming temperatures on Arctic wildlife, leaving the importance of heat stress unclear. Here, we assessed the direct effects of increasing air temperatures on the physiology of thick-billed murres (Uria lomvia), an Arctic seabird with reported mortalities due to heat stress while nesting on sun-exposed cliffs.

Poor prey quality is compensated by higher provisioning effort in passerine birds.

In altricial avian species, nutrition can significantly impact nestling fitness by increasing their survival and recruitment chances after fledging. Therefore, the effort invested by parents towards provisioning nestlings is crucial and represents a critical link between habitat resources and reproductive success. Recent studies suggest that the provisioning rate has little or no effect on the nestling growth rate.

Limited heat tolerance in an Arctic passerine: Thermoregulatory implications for cold-specialized birds in a rapidly warming world.

Arctic animals inhabit some of the coldest environments on the planet and have evolved physiological mechanisms for minimizing heat loss under extreme cold. However, the Arctic is warming faster than the global average and how well Arctic animals tolerate even moderately high air temperatures ( ) is unknown.Using flow-through respirometry, we investigated the heat tolerance and evaporative cooling capacity of snow buntings (; ≈31 g,  = 42), a cold specialist, Arctic songbird.

Wintering Snow Buntings Elevate Cold Hardiness to Extreme Levels but Show No Changes in Maintenance Costs.

AbstractResident temperate passerines adjust their phenotypes to cope with winter constraints, with peak performance in metabolic traits typically occurring during the coldest months. However, it is sparsely known whether cold-adapted northern species make similar adjustments when faced with variable seasonal environments. Life in near-constant cold could be associated with limited flexibility in traits underlying cold endurance.

Deltopectoral vs. deltoid split approach for proximal HUmerus fracture fixation with locking plate: a prospective RAndomized study (HURA).

Background: This study aimed to compare the functional and clinical outcomes between the deltoid split (DS) approach and the classic deltopectoral (DP) approach for locking plate fixation of proximal humerus fractures (PHF) in a prospective randomized multicenter study.

Methods: From 2007 to 2015, all patients with a PHF Neer II/III were invited to participate. Exclusion criteria were pre-existing pathology to the limb, patient refusing or too ill to undergo surgery, patient needing another type of treatment (nail, arthroplasty), and axillary nerve impairment.

WHOLE GENOME SEQUENCING OF AN AVIPOXVIRUS ASSOCIATED WITH INFECTIONS IN A GROUP OF AVIARY-HOUSED SNOW BUNTINGS ().

Avipoxvirus infections have been reported in both free-ranging and domestic birds worldwide. Fowlpox and canarypox viruses belong to the genus among the virus family . They cause cutaneous lesions with proliferative growths on the unfeathered parts of the skin and/or diphtheritic lesions generally associated with necrosis in the upper respiratory and digestive tracts.

Physiological and Immune Responses of Free-Living Temperate Birds Provided a Gradient of Food Supplementation.

Food availability might sometimes be unpredictable for wild birds. To alleviate this possible food limitation, millions of households in North America provide food supplementation to bird populations. However, the ecoimmunological impacts of this supplementation on free-living birds are largely unclear.

Large muscles are beneficial but not required for improving thermogenic capacity in small birds.

It is generally assumed that small birds improve their shivering heat production capacity by developing the size of their pectoralis muscles. However, some studies have reported an enhancement of thermogenic capacity in the absence of muscle mass variation between seasons or thermal treatments. We tested the hypothesis that an increase in muscle mass is not a prerequisite for improving avian thermogenic capacity.