Tracking repeat migratory journeys of individual animals is required to assess phenotypic plasticity of individual migration behaviour in space and time. We used light-level geolocators to track the ...long-distance journeys of migratory songbirds (wood thrush, Hylocichla mustelina), and, for the first time, repeat journeys of individuals. We compare between- and within-individual variation in migration to examine flexibility of timing and route in spring and autumn. Date of departure from wintering sites in Central America, along with sex and age factors, explained most of the variation (71%) in arrival date at North American breeding sites. Spring migration showed high within-individual repeatability in timing, but not in route. In particular, spring departure dates of individuals were highly repeatable, with a mean difference between years of just 3 days. Autumn migration timing and routes were not repeatable. Our results provide novel evidence of low phenotypic plasticity in timing of spring migration, which may limit the ability of individuals to adjust migration schedules in response to climate change.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Interventions that lead to earlier liberation from mechanical ventilation can improve patient outcomes. This guideline, a collaborative effort between the American Thoracic Society and the American ...College of Chest Physicians, provides evidence-based recommendations to optimize liberation from mechanical ventilation in critically ill adults.
Two methodologists performed evidence syntheses to summarize available evidence relevant to key questions about liberation from mechanical ventilation. The methodologists appraised the certainty in the evidence (i.e., the quality of evidence) using the Grading of Recommendations, Assessment, Development, and Evaluation approach and summarized the results in evidence profiles. The guideline panel then formulated recommendations after considering the balance of desirable consequences (benefits) versus undesirable consequences (burdens, adverse effects, and costs), the certainty in the evidence, and the feasibility and acceptability of various interventions. Recommendations were rated as strong or conditional.
The guideline panel made four conditional recommendations related to rehabilitation protocols, ventilator liberation protocols, and cuff leak tests. The recommendations were for acutely hospitalized adults mechanically ventilated for more than 24 hours to receive protocolized rehabilitation directed toward early mobilization, be managed with a ventilator liberation protocol, be assessed with a cuff leak test if they meet extubation criteria but are deemed high risk for postextubation stridor, and be administered systemic steroids for at least 4 hours before extubation if they fail the cuff leak test.
The American Thoracic Society/American College of Chest Physicians recommendations are intended to support healthcare professionals in their decisions related to liberating critically ill adults from mechanical ventilation.
Artificial light at night (ALAN) is increasing at a high rate across the globe and can cause shifts in animal phenology due to the alteration of perceived photoperiod. Birds in particular may be ...highly impacted due to their use of extra-retinal photoreceptors, as well as the use of photoperiodic cues to time life events such as reproduction, moult, and migration. For the first time, we used light-logging geolocators to determine the amount of ALAN experienced by long-distance migratory songbirds (purple martin; Progne subis) while at their overwintering sites in South America to measure its potential relationship with spring migration timing. Almost a third of birds (48/155; 31%) were subjected to at least one night with ALAN over 30 days prior to spring migration. Birds that experienced the highest number of nights (10+) with artificial light departed for spring migration on average 8 days earlier and arrived 8 days earlier at their breeding sites compared to those that experienced no artificial light. Early spring migration timing due to pre-migration ALAN experienced at overwintering sites could lead to mistiming with environmental conditions and insect abundance on the migratory route and at breeding sites, potentially impacting survival and/or reproductive success. Such effects would be particularly detrimental to species already exhibiting steep population declines such as purple martins and other migratory aerial insectivores.
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•One third of spring pre-migratory birds experienced at least one night with ALAN.•Light levels were well above levels seen to impact avian reproductive phenology.•Birds with the most ALAN (+10 days) had an advanced spring departure date of over one week.•Birds with high ALAN also arrived over one week earlier than those without ALAN.•Migration duration was not influenced by ALAN at overwintering sites.
Spring migration timing was more than a week earlier for birds experiencing the highest levels of ALAN.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Similar to other jurisdictions across North America, populations of temperate‐nesting giant Canada geese (Branta canadensis maxima) have increased to unprecedented levels in Manitoba, Canada, causing ...extensive damage to crops and property, posing risks to human safety, and mostly avoiding mortality risk from fall hunting seasons. As a result, this population in southern Manitoba was declared overabundant in 2019, through an amendment to the Canada Migratory Birds Regulations. Management authorities sought to increase harvest rates by introducing an additional hunting period in spring, or conservation season, wherein harvest could be concentrated on this population. An important consideration was the need to avoid additional harvest on non‐target populations that do not meet the criteria to be classified as overabundant, specifically, sub‐arctic nesting Canada geese (Branta canadensis interior) and mid‐continent cackling geese (Branta hutchinsii hutchinsii). To investigate differences in migration timing of populations, and ultimately determine start and closure dates for the spring conservation season, we deployed light‐level geolocators on adult females of each population between 2016 and 2018. We used Bayesian approaches to derive locations from light‐level data and generalized linear mixed models to investigate potential differences in timing of international border crossing among goose populations. Migration data confirmed that movement of these populations overlapped extensively in fall, but in spring, a narrow period existed where mainly the target population was present. Our findings provide the basis for decisions about timing of spring conservation seasons for overabundant temperate‐nesting Canada geese in Manitoba, the first season of its kind for this population in North America. Additionally, our work represents the first large‐scale use of light‐level geolocator technology for assisting with waterfowl harvest management decisions.
Temperate‐breeding giant Canada geese have been declared overabundant in Manitoba, Canada; thus, spring hunting seasons have been considered to reduce their numbers. To help increase harvest rates in these regions, we used tracking data obtained from light‐level geolocators to investigate potential differences in spring migration timing among target and non‐target goose populations. We found a narrow time period where the target population was mainly present, and our findings provide a basis for decision making regarding the timing of spring conservation seasons.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Hippocampal place cells underlie spatial navigation and memory. Remarkably, CA1 pyramidal neurons can form new place fields within a single trial by undergoing rapid plasticity. However, local ...feedback circuits likely restrict the rapid recruitment of individual neurons into ensemble representations. This interaction between circuit dynamics and rapid feature coding remains unexplored. Here, we developed “all-optical” approaches combining novel optogenetic induction of rapidly forming place fields with 2-photon activity imaging during spatial navigation in mice. We find that induction efficacy depends strongly on the density of co-activated neurons. Place fields can be reliably induced in single cells, but induction fails during co-activation of larger subpopulations due to local circuit constraints imposed by recurrent inhibition. Temporary relief of local inhibition permits the simultaneous induction of place fields in larger ensembles. We demonstrate the behavioral implications of these dynamics, showing that our ensemble place field induction protocol can enhance subsequent spatial association learning.
•Rapidly forming place fields can be optogenetically induced in mouse CA1 neurons•Feedback inhibition limits rapid place field induction to fewer principal neurons•Suppressing local inhibition allows induction of place fields in larger ensembles•Ensemble place field induction can enhance subsequent spatial association learning
Rolotti, Ahmed, Szoboszlay et al. develop “all-optical” strategies to induce rapidly forming place fields in mouse CA1 and find that local feedback inhibition restricts recruitment of neurons into ensemble representations. Temporary relief of local inhibition permits the simultaneous induction of place fields in larger ensembles to enhance subsequent association learning.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The impact of climate change on spring phenology poses risks to migratory birds, as migration timing is controlled predominantly by endogenous mechanisms. Despite recent advances in our understanding ...of the underlying genetic basis of migration timing, the ways that migration timing phenotypes in wild individuals may map to specific genomic regions requires further investigation. We examined the genetic architecture of migration timing in a long-distance migratory songbird (purple martin, Progne subis subis) by integrating genomic data with an extensive dataset of direct migratory tracks. A moderate to large amount of variance in spring migration arrival timing was explained by genomics (proportion of phenotypic variation explained by genomics = 0.74; polygenic score R
= 0.24). On chromosome 1, a region that was differentiated between migration timing phenotypes contained genes that could facilitate nocturnal flights and act as epigenetic modifiers. Overall, these results advance our understanding of the genomic underpinnings of migration timing.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Juvenile songbirds on spring migration travel from tropical wintering sites to temperate breeding destinations thousands of kilometres away with no prior experience to guide them. We provide a first ...glimpse at the migration timing, routes, and stopover behaviour of juvenile wood thrushes (Hylocichla mustelina) on their inaugural spring migration by using miniaturized archival geolocators to track them from Central America to the U.S. and Canada. We found significant differences between the timing of juvenile migration and that of more experienced adults: juveniles not only departed later from tropical wintering sites relative to adults, they also became progressively later as they moved northward. The increasing delay was driven by more frequent short stops by juveniles along their migration route, particularly in the U.S. as they got closer to breeding sites. Surprisingly, juveniles were just as likely as adults to cross the Gulf of Mexico, an open-water crossing of 800-1000 km, and migration route at the Gulf was not significantly different for juveniles relative to adults. To determine if the later departure of juveniles was related to poor body condition in winter relative to adults, we examined percent lean body mass, fat scores, and pectoral muscle scores of juvenile versus adult birds at a wintering site in Belize. We found no age-related differences in body condition. Later migration timing of juveniles relative to adults could be an adaptive strategy (as opposed to condition-dependent) to avoid the high costs of fast migration and competition for breeding territories with experienced and larger adults. We did find significant differences in wing size between adults and juveniles, which could contribute to lower flight efficiency of juveniles and thus slower overall migration speed. We provide the first step toward understanding the "black box" of juvenile songbird migration by documenting their migration timing and en route performance.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This clinical practice guideline addresses six questions related to liberation from mechanical ventilation in critically ill adults. It is the result of a collaborative effort between the American ...Thoracic Society and the American College of Chest Physicians.
A multidisciplinary panel posed six clinical questions in a Population, Intervention, Comparator, and Outcomes format. A comprehensive literature search and evidence synthesis was performed for each question, which included appraising the certainty in the evidence (i.e., the quality of evidence) using the Grading of Recommendations, Assessment, Development, and Evaluation approach. The Evidence-to-Decision framework was applied to each question, requiring the panel to evaluate and weigh the importance of the problem, the confidence in the evidence, the certainty about how much the public values the main outcomes, the magnitude and balance of desirable and undesirable outcomes, the resources and costs associated with the intervention, the impact on health disparities, and the acceptability and feasibility of the intervention.
Evidence-based recommendations were formulated and graded initially by subcommittees and then modified after full-panel discussions. The recommendations were confirmed by confidential electronic voting; approval required that at least 80% of the panel members agree with the recommendation.
The panel provides recommendations regarding liberation from mechanical ventilation. The details regarding the evidence and rationale for each recommendation are presented in the American Journal of Respiratory and Critical Care Medicine and Chest.
Remyelination requires the generation of new oligodendrocytes (OLs), which are derived from oligodendrocyte progenitor cells (OPCs). Maturation of OPCs into OLs is a multi-step process. Here, we ...describe a microRNA expressed by OLs, miR-27a, as a regulator of OL development and survival. Increased levels of miR-27a were found in OPCs associated with multiple sclerosis (MS) lesions and in animal models of demyelination. Increased levels of miR-27a led to inhibition of OPC proliferation by cell-cycle arrest, as well as impaired differentiation of human OPCs (hOPCs) and myelination by dysregulating the Wnt-β-catenin signaling pathway. In vivo administration of miR-27a led to suppression of myelinogenic signals, leading to loss of endogenous myelination and remyelination. Our findings provide evidence supporting a critical role for a steady-state level of OL-specific miR-27a in supporting multiple steps in the complex process of OPC maturation and remyelination.
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•miR-27a is expressed by OL lineage cells•Increased expression of miR-27a stalls OPCs at precursor stage•Higher levels of miR-27a is detected during demyelination•Exogenous administration of miR-27a leads to impaired developmental myelination and remyelination failure
Generation of mature oligodendrocytes (OLs) from its progenitors is a controlled process. In this study, Tripathi et al. describes the role of miR-27a, expressed by oligodendrocyte lineage cells, in affecting multiple stages of this process. While miR-27a is needed for generation of mature OLs, increased levels of miR-27a is detected during demyelination and leads to failed remyelination.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP