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Characterization of the Shape Anisotropy of Superparamagnetic Iron Oxide Nanoparticles during Thermal Decomposition

Magnetosomes are near-perfect intracellular magnetite nanocrystals found in magnetotactic bacteria. Their synthetic imitation, known as superparamagnetic iron oxide nanoparticles (SPIONs), have found applications in a variety of (nano)medicinal fields such as magnetic resonance imaging contrast agents, multimodal imaging and drug carriers. In order to perform these functions in medicine, shape and size control of the SPIONs is vital. We sampled SPIONs at ten-minutes intervals during the high-temperature thermal decomposition reaction. Their shape (sphericity and anisotropy) and geometric description (volume and surface area) were retrieved using three-dimensional imaging techniques, which allowed to reconstruct each particle in three dimensions, followed by stereological quantification methods. The results, supported by small angle X-ray scattering characterization, reveal that SPIONs initially have a spherical shape, then grow increasingly asymmetric and irregular. A high heterogeneity in volume at the initial stages makes place for lower particle volume dispersity at later stages. The SPIONs settled into a preferred orientation on the support used for transmission electron microscopy imaging, which hides the extent of their anisotropic nature in the axial dimension, there by biasing the interpretation of standard 2D micrographs. This information could be feedback into the design of the chemical processes and the characterization strategies to improve the current applications of SPIONs in nanomedicine.

opencc-zeroJun 2020View details →

nkx3.2 mutant zebrafish accommodate jaw joint loss through a phenocopy of the head shapes of Paleozoic jawless fish

The vertebrate jaw is a versatile feeding apparatus. To function, it requires a joint between the upper and lower jaws, so jaw joint defects are often highly disruptive and difficult to study. To describe the consequences of jaw-joint dysfunction, we engineered two independent null alleles of a single jaw-joint marker gene, nkx3.2, in zebrafish. These mutations caused zebrafish to become functionally jawless via fusion of the upper and lower jaw cartilages (ankylosis). Despite lacking jaw joints, nkx3.2 mutants survived to adulthood and accommodated this defect by: a) remodeling their skulls; and b) altering their behavior from suction feeding to ram feeding. As a result, nkx3.2 mutants developed skull shapes superficially similar to those observed in two lineages of ancient jawless vertebrates (anaspids and furcacaudiid thelodonts), including: a fixed open gape, reduced snout, and enlarged branchial region. However, no homology exists in individual skull elements between these taxa, and most of the modified elements in the mutant zebrafish occur outside known expression domains of nkx3.2. Therefore, we interpret the adult nkx3.2 phenotype not as a reversal to an ancestral state, but as convergence due to similar functional requirements of feeding without moveable jaws. This remarkable convergence strongly suggests that jaw movements themselves dramatically influence the development of jawed vertebrate skulls. Thus, these mutants provide a unique model with which to: a) investigate adaptive responses to perturbation in skeletal development; b) re-evaluate evolutionarily inspired interpretations of phenocopies generated by gene knockdowns and knockouts; and c) gain insights into feeding mechanics of the extinct agnathans.

Data from: Starving the enemy? Feeding behavior shapes host-parasite interactions

The loss of appetite that typically accompanies infection or the mere exposure to parasites is traditionally considered a negative by-product of infection, benefitting neither the host nor the parasite. In fact, numerous medical and veterinary practices directly or indirectly subvert this 'illness-mediated anorexia'. However, the ecological factors that influence it, its effects on disease outcomes, or why it evolved remains poorly resolved. We explore how hosts use anorexia to defend against infection and how parasites can manipulate anorexia to enhance transmission. Then, we use a coevolutionary model to illustrate how changes to anorexia could alter disease dynamics and virulence evolution. Anorexia could be exploited to improve host health and disease management; we propose an interdisciplinary approach to minimize unintended consequences.

Data from: Climate, soil resources and microbial activity shape the distributions of mountain plants based on their functional traits

While soil ecosystems undergo important modi cations due to global change, the e ect of soil properties on plant distributions is still poorly understood. Plant growth is not only controlled by soil physico-chemistry but also by microbial activities through the decomposition of organic matter and the recycling of nutrients essential for plants. A growing body of evidence also suggests that plant functional traits modulate spe- cies' response to environmental gradients. However, no study has yet contrasted the importance of soil physico-chemistry, microbial activities and climate on plant species distributions, while accounting for how plant functional traits can in uence species- speci c responses. Using hierarchical e ects in a multi-species distribution model, we investigate how four functional traits related to resource acquisition (plant height, leaf carbon to nitro- gen ratio, leaf dry matter content and speci c leaf area) modulate the response of 44 plant species to climatic variables, soil physico-chemical properties and microbial 100 decomposition activity (i.e. exoenzymatic activities) in the French Alps. Our hierarchical trait-based model allowed to predict well 41 species according to the TSS statistic. In addition to climate, the combination of soil C/N, as a measure of organic matter quality, and exoenzymatic activity, as a measure of microbial decom- position activity, strongly improved predictions of plant distributions. Plant traits played an important role. In particular, species with conservative traits performed bet- ter under limiting nutrient conditions but were outcompeted by exploitative plants in more favorable environments. We demonstrate tight associations between microbial decomposition activity, plant functional traits associated to di erent resource acquisition strategies and plant dis- tributions. is highlights the importance of plant–soil linkages for mountain plant distributions. ese results are crucial for biodiversity modelling in a world where both climatic and soil systems are undergoing profound and rapid transformations.

Demographic history shaped geographical patterns of deleterious mutation load in a broadly distributed Pacific Salmon

A thorough reconstruction of historical processes is essential for a comprehensive understanding the mechanisms shaping patterns of genetic diversity. Indeed, past and current conditions influencing effective population size have important evolutionary implications for the efficacy of selection, increased accumulation of deleterious mutations, and loss of adaptive potential. Here, we gather extensive genome-wide data that represent the extant diversity of the Coho salmon (Oncorhynchus kisutch) to address two objectives. We demonstrate that a single glacial refugium is the source of most of the present-day genetic diversity, with detectable inputs from a putative secondary micro-refugium. We found statistical support for a scenario whereby ancestral populations located south of the ice sheets expanded in postglacial time, swamping out most of the diversity from other putative micro-refugia. Demographic inferences revealed that genetic diversity was also affected by linked selection in large parts of the genome. Moreover, we demonstrate that the recent demographic history of this species generated regional differences in the load of deleterious mutations among populations, a finding that mirrors recent results from human populations and provides increased support for models of expansion load. We propose that insights from these historical inferences should be better integrated in conservation planning of wild organisms, which currently focuses largely on neutral genetic diversity and local adaptation, with the role of potentially maladaptive variation being generally ignored.

Figure 2 from: Tung G-S, Liao Y-C, Burckhardt D, Yang M-M (2020) Trioza turouguei sp. nov. (Hemiptera, Psylloidea, Triozidae), a new psyllid species from Taiwan inducing pea-shaped stem galls on Cinnamomum osmophloeum (Lauraceae), with notes on its galling biology. ZooKeys 958: 91-106. https://doi.org/10.3897/zookeys.958.52977

Figure 2 Trioza turouguei sp. nov. A head B antenna C hind leg D forewing. Scale bars: 0.1 mm (A, B, C); 1 mm (D).

Figure 1 from: Tung G-S, Liao Y-C, Burckhardt D, Yang M-M (2020) Trioza turouguei sp. nov. (Hemiptera, Psylloidea, Triozidae), a new psyllid species from Taiwan inducing pea-shaped stem galls on Cinnamomum osmophloeum (Lauraceae), with notes on its galling biology. ZooKeys 958: 91-106. https://doi.org/10.3897/zookeys.958.52977

Figure 1 Adults of Trioza turouguei sp. nov. A male, dorsal view B male, lateral view C female, dorsal view D female, lateral view. Scale bars: 1 mm.

Figure 5 from: Tung G-S, Liao Y-C, Burckhardt D, Yang M-M (2020) Trioza turouguei sp. nov. (Hemiptera, Psylloidea, Triozidae), a new psyllid species from Taiwan inducing pea-shaped stem galls on Cinnamomum osmophloeum (Lauraceae), with notes on its galling biology. ZooKeys 958: 91-106. https://doi.org/10.3897/zookeys.958.52977

Figure 5 Trioza turouguei sp. nov. on its host plant, Cinnamomum osmophloeum Kanehira A male B female C pea-like galls on stem D fifth instar immature in a gall.

Figure 4 from: Tung G-S, Liao Y-C, Burckhardt D, Yang M-M (2020) Trioza turouguei sp. nov. (Hemiptera, Psylloidea, Triozidae), a new psyllid species from Taiwan inducing pea-shaped stem galls on Cinnamomum osmophloeum (Lauraceae), with notes on its galling biology. ZooKeys 958: 91-106. https://doi.org/10.3897/zookeys.958.52977

Figure 4 Fifth instar immature of Trioza turouguei sp. nov. A habitus B marginal sectasetae of head C marginal sectasetae of forewing pad D marginal sectasetae of hindwing pad E marginal sectasetae of caudal plate F tarsal arolium G antenna H circumanal ring. Scale bars: 0.1 mm.

Figure 3 from: Tung G-S, Liao Y-C, Burckhardt D, Yang M-M (2020) Trioza turouguei sp. nov. (Hemiptera, Psylloidea, Triozidae), a new psyllid species from Taiwan inducing pea-shaped stem galls on Cinnamomum osmophloeum (Lauraceae), with notes on its galling biology. ZooKeys 958: 91-106. https://doi.org/10.3897/zookeys.958.52977

Figure 3 Terminalia of Trioza turouguei sp. nov. in lateral view A male terminalia B paramere, inner surface C distal portion of aedeagus D female terminalia E detail of female circumanal ring. Scale bars: 0.2 mm (A, D, E); 0.1 mm (B, C).

Figure 2 from: Monjardim M, Azevedo CO, Fagundes V (2020) DNA barcoding and hypopygium shape support delimitation of sympatric Dissomphalus species (Hymenoptera, Bethylidae) from the Atlantic rainforest. ZooKeys 959: 87-97. https://doi.org/10.3897/zookeys.959.53737

Figure 2 A bayesian consensus tree generated from the 304-bp COI from 29 representatives of the species complex. Posterior probabilities (PP) and bootstrap (BT) indicated above branches. The species D. thaianus, D. wusheanus and D. chiangmaiensis were used as outgroups to root the tree B–D hypopygium magnified 9.2×, corresponding to each clade.

Figure 1 from: Monjardim M, Azevedo CO, Fagundes V (2020) DNA barcoding and hypopygium shape support delimitation of sympatric Dissomphalus species (Hymenoptera, Bethylidae) from the Atlantic rainforest. ZooKeys 959: 87-97. https://doi.org/10.3897/zookeys.959.53737

Figure 1 Locations of the samples in Brazil and Paraguay (see Appendix I for geographic coordinates).

Data from: Ecology shapes epistasis in a genotype-phenotype-fitness map for stick insect colour

Genetic interactions such as epistasis are widespread in nature and can shape evolutionary dynamics. Epistasis occurs due to non-linearity in biological systems, which can arise via cellular processes that convert genotype to phenotype and via selective processes that connect phenotype to fitness. Few studies in nature have connected genotype to phenotype to fitness for multiple potentially interacting genetic variants. Thus, the causes of epistasis in the wild remain poorly understood. Here, we show that epistasis for fitness is an emergent and predictable property of non-linear selective processes. We do so by measuring the genetic basis of cryptic colouration and survival in a field experiment with stick insects. We find that colouration exhibits a largely additive genetic basis, but with some effects of epistasis that enhance differentiation between colour morphs. In terms of fitness, different combinations of loci affecting colouration confer high survival in one host-plant treatment. Specifically, non-linear correlational selection for specific combinations of colour traits in this treatment drives the emergence of pairwise and higher-order epistasis for fitness at loci underlying colour. In turn, this results in a rugged fitness landscape for genotypes. In contrast, fitness epistasis was dampened in another treatment, where selection was weaker. Patterns of epistasis that are shaped by ecologically based selection could be common, and central to understanding fitness landscapes, the dynamics of evolution, and potentially other complex systems.

Accelerated brain shape evolution is associated with rapid diversification in an avian radiation

Niche expansion is a critical step in the speciation process. Large brains linked to improved cognitive ability may enable species to expand their niches and forage in new ways, thereby promoting speciation. Despite considerable work on ecological divergence in brain size and its importance in speciation, relatively little is known about how brain shape relates to behavioral, ecological, and taxonomic diversity at macroevolutionary scales. This is due, in part, to inherent challenges with quantifying brain shape across many species. Here, we present a novel, semiautomated approach for rapidly phenotyping brain shape using semilandmarks derived from X-ray computed micro-tomography (microCT) scans. We then test its utility by parsing evolutionary trends within a diverse radiation of birds, kingfishers (Aves: Alcedinidae). Multivariate comparative analyses reveal that rates of brain shape evolution, but not beak shape, are positively correlated with lineage diversification rates. Distinct brain shapes are further associated with changes in body size and foraging behavior, suggesting both allometric and ecological constraints on brain shape evolution. These results are in line with the idea of brains acting as a "master regulator" of critical processes governing speciation, such as dispersal, foraging behavior, and dietary niche.

Reactivation of latent infections with migration shapes population-level disease dynamics

Annual migration is common across animal taxa and can dramatically shape the spatial and temporal patterns of infectious disease. Although migration can decrease infection prevalence in some contexts, these energetically costly long-distance movements can also have immunosuppressive effects that may interact with transmission processes in complex ways. Here we develop a mechanistic model for the reactivation of latent infections driven by physiological changes or energetic costs associated with migration (i.e., "migratory relapse") and its effects on disease dynamics. We determine conditions under which migratory relapse can amplify or reduce infection prevalence across pathogen and host traits (e.g., infectious periods, virulence, overwinter survival, timing of relapse) and transmission phenologies. We show that relapse at either the start or end of migration can dramatically increase prevalence across the annual cycle and may be crucial for maintaining pathogens with low transmissibility and short infectious periods in migratory populations. Conversely, relapse at the start of migration can reduce the prevalence of highly virulent pathogens by amplifying culling of infected hosts during costly migration, especially for highly transmissible pathogens and those transmitted during migration or the breeding season. Our study provides a mechanistic foundation for understanding the spatiotemporal patterns of relapsing infections in migratory hosts, with implications for zoonotic surveillance and understanding how infection patterns will respond to shifts in migratory propensity associated with environmental change. Further, our work suggests incorporating within-host processes into population-level models of pathogen transmission may be crucial for reconciling the range of migration–infection relationships observed across migratory species.

DBpedia SHACL shapes

SHACL Shapes extracted from the DBpedia ontology.

opencc-zeroSep 2020View details →

Regional wind patterns likely shape a seasonal migration detour

Migrating animals should optimise time and energy use when migrating, travelling directly to their destination. Detours from the most direct route may arise however because of barriers and weather conditions. Identifying how such situations arise from variable weather conditions is crucial to understand population response in the light of increased anthropogenic climate change. Here we used light-level geolocators to follow Cyprus wheatears for their full annual cycle in two separate years migrating between Cyprus, over the Mediterranean and the Sahara to winter in north-east sub-Saharan Africa. We predicted that any route detours would be related to wind conditions experienced during migration. We found that spring migration for all birds included an eastern detour, whilst autumn migrations were direct across the Sahara. The direct autumn migration was likely a consequence of consistent tail-winds, whilst the eastern detour in spring is likely to be more efficient given the wind conditions which are against a direct route. Such variable migration routes shaped by coincidence with prevailing winds are probably common suggesting that some birds may be able to adapt to future changes in wind conditions.

Figure 7 from: Li Y, Liu C, Lin L, Li Y, Xiao J, Loh K-H (2020) Pleistocene isolation caused by sea-level fluctuations shaped genetic characterization of Pampus minor over a large-scale geographical distribution. ZooKeys 969: 137-154. https://doi.org/10.3897/zookeys.969.52069

Figure 7 BSPs showing NefT (Nef = effective population size; T = generation time) changes over time for P. minor based on Cytb sequences. The upper and lower limits of the blue line represent the 95% confidence intervals of highest posterior densities (HPD) analysis. The solid black line represents median estimates of NefT.

Figure 5 from: Li Y, Liu C, Lin L, Li Y, Xiao J, Loh K-H (2020) Pleistocene isolation caused by sea-level fluctuations shaped genetic characterization of Pampus minor over a large-scale geographical distribution. ZooKeys 969: 137-154. https://doi.org/10.3897/zookeys.969.52069

Figure 5 Matrix of pairwise FST values between 11 P. minor populations based on Cytb sequences. * significant at p < 0.05 by the permutation test, ** extremely significant at p < 0.01 by the permutation test.

Figure 6 from: Li Y, Liu C, Lin L, Li Y, Xiao J, Loh K-H (2020) Pleistocene isolation caused by sea-level fluctuations shaped genetic characterization of Pampus minor over a large-scale geographical distribution. ZooKeys 969: 137-154. https://doi.org/10.3897/zookeys.969.52069

Figure 6 The expected mismatch distributions under a sudden expansion model (solid gray line) and the observed pairwise difference (black bars) of Cytb haplotypes of P. minor.