Thermal ecology and baseline energetic requirements of a large‐bodied ectotherm suggest resilience to climate change

1. Most studies on how rising temperatures will impact terrestrial ectotherms have focused on single populations or multiple sympatric species. Addressing the thermal and energetic implications of climatic variation on multiple allopatric populations of a species will help us better understand how a species may be impacted by altered climates.
2. We used eight years of thermal and behavioral data collected from four populations of Pacific rattlesnakes (Crotalus oreganus) living in climatically distinct habitat types (inland and coastal) to determine the field‐active and laboratory‐preferred body temperatures, thermoregulatory metrics, and maintenance energetic requirements of snakes from each population.
3. Physical models showed that thermal quality was best at coastal sites, but inland snakes thermoregulated more accurately despite being in more thermally constrained environments. Projected increases of 1 and 2°C in ambient temperature result in an increase in overall thermal quality at both coastal and inland sites.
4. Population differences in modeled standard metabolic rate estimates were driven by body size and not field‐active body temperature, with inland snakes requiring 1.6× more food annually than coastal snakes.
5. All snakes thermoregulated with high accuracy, suggesting that small increases in ambient temperature are unlikely to impact the maintenance energetic requirements of individual snakes and that some species of large‐bodied reptiles may be robust to modest thermal perturbations under conservative climate change predictions.

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Mouse model systems of autism spectrum disorder: Replicability and informatics signature

Phenotyping mouse model systems of human disease has proven to be a difficult task, with frequent poor inter‐ and intra‐laboratory replicability, particularly in behavioral domains such as social and cognitive function. However, establishing robust animal model systems with strong construct validity is of fundamental importance as they are central tools for understanding disease pathophysiology and developing therapeutics. To complete our studies of mouse model systems relevant to autism spectrum disorder (ASD), we present a replication of the main findings from our two published studies of five genetic mouse model systems of ASD. To assess the intra‐laboratory robustness of previous results, we chose the two model systems that showed the greatest phenotypic differences, the Shank3/F and Cntnap2, and repeated assessments of general health, activity and social behavior. We additionally explored all five model systems in the same framework, comparing all results obtained in this three‐yearlong effort using informatics techniques to assess commonalities and differences. Our results showed high intra‐laboratory replicability of results, even for those with effect sizes that were not particularly large, suggesting that discrepancies in the literature may be dependent on subtle but pivotal differences in testing conditions, housing enrichment, or background strains and less so on the variability of the behavioral phenotypes. The overall informatics analysis suggests that in our behavioral assays we can separate the set of tested mouse model system into two main classes that in some aspects lie on opposite ends of the behavioral spectrum, supporting the view that autism is not a unitary concept.     

Contribution of Val/Ile87 residue in the extracellular domain in agonist-induced current responses of the human and rat P2X7 receptors

Purinergic Signalling - The P2X7 receptor (P2X7R) is an ATP-gated cation channel with a critical role in many physiological and pathological processes, and shows prominent functional differences...     

Changes in Nkx2.1, Sox2, Bmp4, and Bmp16 expression underlying the lung‐to‐gas bladder evolutionary transition in ray‐finned fishes

The key to understanding the evolutionary origin and modification of phenotypic traits is revealing the responsible underlying developmental genetic mechanisms. An important organismal trait of ray‐finned fishes is the gas bladder, an air‐filled organ that, in most fishes, functions for buoyancy control, and is homologous to the lungs of lobe‐finned fishes. The critical morphological difference between lungs and gas bladders, which otherwise share many characteristics, is the general direction of budding during development. Lungs bud ventrally and the gas bladder buds dorsally from the anterior foregut. We investigated the genetic underpinnings of this ventral‐to‐dorsal shift in budding direction by studying the expression patterns of known lung genes (Nkx2.1, Sox2, and Bmp4) during the development of lungs or gas bladder in three fishes: bichir, bowfin, and zebrafish. Nkx2.1 and Sox2 show reciprocal dorsoventral expression patterns during tetrapod lung development and are important regulators of lung budding; their expression during bichir lung development is conserved. Surprisingly, we find during gas bladder development, Nkx2.1 and Sox2 expression are inconsistent with the hypothesis that they regulate the direction of gas bladder budding. Bmp4 is expressed ventrally during lung development in bichir, akin to the pattern during mouse lung development. During gas bladder development, Bmp4 is not expressed. However, Bmp16, a paralogue of Bmp4, is expressed dorsally in the developing gas bladder of bowfin. Bmp16 is present in the known genomes of Actinopteri (ray‐finned fishes excluding bichir) but absent from mammalian genomes. We hypothesize that Bmp16 was recruited to regulate gas bladder development in the Actinopteri in place of Bmp4.     

Miro: A molecular switch at the center of mitochondrial regulation

The orchestration of mitochondria within the cell represents a critical aspect of cell biology. At the center of this process is the outer mitochondrial membrane protein, Miro. Miro coordinates diverse cellular processes by regulating connections between organelles and the cytoskeleton that range from mediating contacts between the endoplasmic reticulum and mitochondria to the regulation of both actin and microtubule motor proteins. Recently, a number of cell biological, biochemical, and protein structure studies have helped to characterize the myriad roles played by Miro. In addition to answering questions regarding Miro's function, these studies have opened the door to new avenues in the study of Miro in the cell. This review will focus on summarizing recent findings for Miro's structure, function, and activity while highlighting key questions that remain unanswered.     

Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene

The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well‐known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ¹³C analysis and δ¹⁵N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ¹⁵N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue‐specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ¹⁵N values than modern populations. Amino acid δ¹⁵N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts.     

Impacts of soil temperature,phenology and plant community composition on invertebrate herbivory in a natural warming experiment

Species and community-level responses to warming are well documented, with plants and invertebrates known to alter their range, phenology or composition as temperature increases. The effects of warming on biotic interactions are less clearly understood, but can have consequences that cascade through ecological networks. Here, we used a natural soil temperature gradient of 5–35°C in the Hengill geothermal valley, Iceland, to investigate the effects of temperature on plant community composition and plant–invertebrate interactions. We quantified the level of invertebrate herbivory on the plant community across the temperature gradient and the interactive effects of temperature, plant phenology (i.e. development stage) and vegetation community composition on the probability of herbivory for three ubiquitous plant species, Cardamine pratensis, Cerastium fontanum and Viola palustris. We found that the percentage cover of graminoids and forbs increased, while the amount of litter decreased, with increasing soil temperature. Invertebrate herbivory also increased with soil temperature at the plant community level, but this was underpinned by different effects of temperature on herbivory for individual plant species, mediated by the seasonal development of plants and the composition of the surrounding vegetation. This illustrates the importance of considering the development stage of organisms in climate change research given the variable effects of temperature on susceptibility to herbivory at different ontogenetic stages.