Chickadees Faced with Unpredictable Food Increase Fat Reserves but Certain Components of Their Immune Function Decline

In winter, temperate resident birds are often faced with periodic low natural food availability. This reduction or unpredictability in resource availability might then have a negative impact on immune function, given that immune system support is highly resource dependent. We investigated the balance between energetic and immune management in captive black-capped chickadees (Poecile atricapilus) by manipulating the predictability of resources. The control group received food ad lib. every day, while the experimental group received a reduced amount of food on random days and food ad lib. on all other days. We measured two key metrics of energetic management (body and fat mass) as well as a suite of immune system components. Compared with control birds, experimental birds maintained significantly higher total body and fat mass, had lower acute phase protein concentrations, and had decreased body temperature and lost more body mass during the fever response following injection with lipopolysaccharides. Interestingly, birds in both groups had similar levels of complement lysis, delayed-type hypersensitivity response (phytohemagglutinin), and primary antibody production (keyhole limpet hemocyanin). This experiment demonstrates that black-capped chickadees strategically increase their fat mass in response to decreased food availability and that this might allow the birds to maintain most of the immune system unaltered, except some of the most costly immune components

Chickadees faced with unpredictable food increase fat reserves but certain components of their immune function decline

In winter, temperate resident birds are often faced with periodic low natural food availability. This reduction or unpredictability in resource availability might then have a negative impact on immune function, given that immune system support is highly resource dependent. We investigated the balance between energetic and immune management in captive black-capped chickadees (Poecile atricapilus) by manipulating the predictability of resources. The control group received food ad lib. every day, while the experimental group received a reduced amount of food on random days and food ad lib. on all other days. We measured two key metrics of energetic management (body and fat mass) as well as a suite of immune system components. Compared with control birds, experimental birds maintained significantly higher total body and fat mass, had lower acute phase protein concentrations, and had decreased body temperature and lost more body mass during the fever response following injection with lipopolysaccharides. Interestingly, birds in both groups had similar levels of complement lysis, delayed-type hypersensitivity response (phytohemagglutinin), and primary antibody production (keyhole limpet hemocyanin). This experiment demonstrates that black-capped chickadees strategically increase their fat mass in response to decreased food availability and that this might allow the birds to maintain most of the immune system unaltered, except some of the most costly immune components

Movement patterns, spatial distribution and depth preference by individual whitefish, Coregonus lavaretus in a small artificial lake

Using manual acoustic tracking our study quantified (1) the spatial distribution (2) the movement patterns and (3) the depth preference of adult whitefish, Coregonus lavaretus in it small artificial lake of eastern Belgium were the species was introduced in 1978 for recreational fishing. From June to October 2004, n=6 C. lavaretus (LF 285-519 mm) were tracked (pingers and depth sensor transmitters) from a small boat over periods ranging from 98 to 108 days in Robertville Lake (elevation: 490 m; area: 63 ha max. depth: 47 in). Whitefish were consistently mobile but showed quite variable lake use patterns. Two individuals traveled the entire length and breadth of the lake, whereas others remained in movement in the deep zone in the middle part of the lake or near the retaining darn wall. Whitefish occupied positions in the water column ranging front 2.6 to 27.0 m (mean 12.7 +/- 5.6 m) that varied depending on individuals. This first study on individual whitefish behaviour provides a better understanding of the behavioural ecology of the species in small artificial lake

Quantitative analogue modelling of the surface deformation associated with cone-sheet and dyke emplacement

International audienceInclined cone-sheets and sub-vertical dykes constitute the two principal types of magmatic sheet intrusionsproduced by volcanic systems. In active volcanic systems, the emplacement of sheet intrusions causes measurablesurface deformation, which is analyzed through geodetic models. Geodetic model output is classically the shape ofunderlying intrusions causing the surface deformation, however, the results of these models are not testable as thesubsurface intrusion is not accessible. Such test would only be doable with a physical system in which both (1) thesurface deformation pattern and (2) the 3D shape of the underlying intrusion are known. In addition, establishedgeodetic models only consider static magma intrusions, and do not account for emplacement and propagationprocesses. This would require combined good time- and space-resolution, which is not achievable with classicalgeodetic monitoring systems.We present a series of analogue models that may be a way of accurately linking surface deformation to theunderlying intrusions and associated emplacement processes. We systematically varied depth of intrusion, thecohesive properties of the silica powder representing the country rock and the velocity of injected magma.The pressure of the intruding vegetable oil was measured through time, and the model surface topography wasmonitored. The low viscosity magma was simulated by molten vegetable oil, which solidified after intrusion; thesolidified intrusion was then excavated and its shape was measured. By linking the development of the surfaceuplift in height, area, and volume with the pressure data from the onset of intrusion until the time of eruption,we identify characteristic laws of surface deformation. First results indicate that the pattern of uplift over timevaries, depending on whether deformation is caused by a dyke- or a cone-sheet-shaped intrusion. The results fromall experiments may enable us to distinguish the two intrusion types using surface deformation data alone. Inaddition, the different signatures of surface deformation patterns associated with dykes and cone sheets providestrong insights into their contrasting emplacement regimes: dykes mainly inject as open fractures, whereas localshear deformation is likely to control cone-sheet emplacement. This key can then be applied to presently activevolcanic areas where surface deformation is monitored

Movements and depth utilisation by the whithefish Coregonus lavaretus and Coregonus peled in a small artificial lake in eastern Belgium.

Using manual acoustic tracking our study quantified (1) the spatial distribution (2) the movement patterns and (3) the depth preference of adult whitefish in a small artificial lake of eastern Belgium were the species was introduced in 1978 for recreational fishing. From June to October 2004, n=6 C. lavaretus (LF 285-519 mm) were tracked (pingers and depth sensor transmitters) from a small boat over periods ranging from 98 to 108 days in Robertville Lake (elevation: 490 m; area: 63 ha; max. depth: 47 m). Whitefish were consistently mobile but showed quite variable lake use patterns. Two individuals traveled the entire length and breadth of the lake, whereas others remained in movement in the deep zone in the middle part of the lake or near the retaining dam wall. Whitefish occupied positions in the water column ranging from 2.6 to 27.0 m (mean 12.7 m ± 5.6 m) that varied depending on individuals. This first study on individual whitefish behaviour provides a better understanding of the behavioural ecology of the species in small artificial lake

Wintering snow buntings elevate cold hardiness to extreme levels but show no changes in maintenance costs

Resident 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. We investigated this by tracking individual physiological changes over five consecutive winters in snow buntings (Plectrophenax nivalis), an Arctic-breeding migratory passerine typically confronted with nearly constant cold. Buntings were held in an outdoor aviary and exposed to seasonal temperature variation typical of temperate zone climates. We measured phenotypic changes in body composition (body, fat, and lean mass, pectoralis muscle thickness), oxygen transport capacity (hematocrit), metabolic performance (basal metabolic rate [BMR] and summit metabolic rate [Msum]), thermogenic endurance (time to reach Msum), and cold tolerance (temperature at Msum). Snow buntings showed flexibility in functions underlying thermogenic capacity and cold endurance comparable to that observed in temperate resident passerines wintering at similar latitudes. Specifically, they increased body mass (13%), fat mass (246%), hematocrit (23%), pectoralis muscle thickness (8%), and Msum (27%). We also found remarkable cold tolerance in these birds, with individuals reaching Msum in helox at temperatures equivalent to less than 2907C in air. However, in contrast with resident temperate passerines, lean mass decreased by 12%, and there was no clear increase in maintenance costs (BMR). Our results show that the flexibility of traits underlying thermal acclimatization in a cold-adapted northern species is comparable to that of temperate resident species living at lower latitudes and is therefore not limited by life in near-constant cold

Type 1 Diabetes in People Hospitalized for COVID-19: New Insights From the CORONADO Study

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The association between macrovascular complications and intensive care admission, invasive mechanical ventilation, and mortality in people with diabetes hospitalized for coronavirus disease-2019 (COVID-19)

International audienceAbstract Background It is not clear whether pre-existing macrovascular complications (ischemic heart disease, stroke or peripheral artery disease) are associated with health outcomes in people with diabetes mellitus hospitalized for COVID-19. Methods We conducted cohort studies of adults with pre-existing diabetes hospitalized for COVID-19 infection in the UK, France, and Spain during the early phase of the pandemic (between March 2020—October 2020). Logistic regression models adjusted for demographic factors and other comorbidities were used to determine associations between previous macrovascular disease and relevant clinical outcomes: mortality, intensive care unit (ICU) admission and use of invasive mechanical ventilation (IMV) during the hospitalization. Output from individual logistic regression models for each cohort was combined in a meta-analysis. Results Complete data were available for 4,106 (60.4%) individuals. Of these, 1,652 (40.2%) had any prior macrovascular disease of whom 28.5% of patients died. Mortality was higher for people with compared to those without previous macrovascular disease (37.7% vs 22.4%). The combined crude odds ratio (OR) for previous macrovascular disease and mortality for all four cohorts was 2.12 (95% CI 1.83–2.45 with an I 2 of 60%, reduced after adjustments for age, sex, type of diabetes, hypertension, microvascular disease, ethnicity, and BMI to adjusted OR 1.53 [95% CI 1.29–1.81]) for the three cohorts. Further analysis revealed that ischemic heart disease and cerebrovascular disease were the main contributors of adverse outcomes. However, proportions of people admitted to ICU (adjOR 0.48 [95% CI 0.31–0.75], I 2 60%) and the use of IMV during hospitalization (adjOR 0.52 [95% CI 0.40–0.68], I 2 37%) were significantly lower for people with previous macrovascular disease. Conclusions This large multinational study of people with diabetes mellitus hospitalized for COVID-19 demonstrates that previous macrovascular disease is associated with higher mortality and lower proportions admitted to ICU and treated with IMV during hospitalization suggesting selective admission criteria. Our findings highlight the importance correctly assess the prognosis and intensive monitoring in this high-risk group of patients and emphasize the need to design specific public health programs aimed to prevent SARS-CoV-2 infection in this subgroup