Noise pollution alters the diet composition of invertebrate consumers both in and beyond a noise-exposed grassland ecosystem

Anthropogenic noise is ubiquitous globally. However, we know little about how the impacts of noise alter fundamental ecosystem properties, such as resource consumption by invertebrate consumers. Using experimental noise manipulation and faecal DNA metabarcoding, we assessed how the direct and cross-trophic indirect effects of noise altered the dietary richness and specializations of omnivorous grasshoppers in a grassland ecosystem. We found that the experimental noise treatment expanded grasshoppers' dietary richness and resulted in dietary generalizations in both noise-exposed and adjacent relatively quieter areas. Unexpectedly, however, these dietary changes were primarily explained by the direct effect of noise not only in the noise-exposed areas but also in the adjacent quieter areas and were relaxed by indirect effects of noise such as reduced birds and predation risk and increased grasshoppers. Our work suggests that noise pollution can be key in explaining the variation of invertebrate consumers' diets across a gradient of noise-exposed environments.

Contagious charisma: the flow of charisma from leader to followers and the role of followers' self-monitoring

Charisma, the captivating attribute that endows an individual with the power to inspire and influence others, is frequently associated with possessing an attractive personality, effective communication skills, and the capacity to draw people in and lead them. The concept of the trickle-down effect in leadership theory suggests that the characteristics of a leader's style including perceptions, emotions, attitudes, and behaviors, have the potential to be "contagious" and spread to their followers. Nevertheless, it is unclear whether and when a leader's charisma may be transferred to followers, as charisma is predominantly a trait associated with the leader. Integrating insights from the social learning, emotional contagion, and self-concept theories, we propose that charisma can cascade downward from the leader to followers and that this effect is contingent on the individual follower's level of self-monitoring. Measuring a sample of 127 followers and 15 leaders in a large organization at two time points, we found that throughout time the leader's charisma indeed cascaded down to followers, i.e., followers of a charismatic leader were perceived as more charismatic throughout time. However, this effect was prominent only for low-monitoring followers. Novel insights into the flow-down effect of charisma, avenues for future research, and practical implications are discussed.

Leveraging Macrophage-Mediated Cancer Immunotherapy via a Cascading Effect Induced by a Molecularly Imprinted Nanocoordinator

Reprogramming tumor-associated macrophages (TAMs) has emerged as a promising strategy in cancer immunotherapy. Targeted therapeutics integrating multiple functions to fully leverage the antitumor immune functions of macrophages without affecting systemic or tissue-resident macrophages are crucial for TAM reprogramming. Herein, by integrating molecular imprinting and nanotechnology, we rationally designed and engineered an unprecedented nanocoordinator for targeted remolding of TAMs to fully leverage the antitumor efficacy of macrophages by inducing a cascade effect. The nanocoordinator features a magnetic iron oxide nanoinner core and sialic acid-imprinted shell. Intravenously administered into systemic circulation, the nanocoordinator can rapidly accumulate at the tumor site in response to an external magnet. Then, by specifically binding to sialic acid overexpressed on tumor cells, the nanocoordinator anchors at the tumor site with prolonged retention time. Via binding with the nanocoordinator, tumor cells are tagged with a foreign substance, which promotes the intrinsic phagocytosis of macrophages. Subsequently, the nanocoordinator taken up by macrophages effectively promotes the polarization of macrophages toward the M1 phenotype, thus activating the immunotherapeutic efficacy of macrophages. Synergized by the cascade effect, this nanocoordinator effectively harnesses TAMs for macrophage-mediated immunotherapy. This study offers new TAM-targeted therapeutics that allows us to fully leverage the antitumor immune functions of macrophages without affecting the normal tissue.

A parasite indirectly affects nutrient distribution by common mycorrhizal networks between host and neighboring plants

Cascading effects are ubiquitous in nature and can modify ecological processes. Most plants have mutualistic associations with mycorrhizal fungi, and can be connected to neighboring plants through common mycorrhizal networks (CMNs). However, little is known about how the distribution of nutrients by CMNs to the interconnected plants is affected by higher trophic levels, such as parasitic plants. We hypothesized that parasitism would indirectly drive CMNs to allocate more nutrients to the nonparasitized neighboring plants rather than to the parasitized host plants, and that this would result in a negative-feedback effect on the growth of the parasitic plant. To test this, we conducted a container experiment, where each container housed two in-growth cores that isolated the root system of a single Trifolium pratense seedling. The formation of CMNs was either prevented or permitted using nylon fabric with a mesh width of 0.5 or 25 μm, respectively. In each container, either both T. pratense plants were not parasitized or only one was parasitized by the holoparasite Cuscuta australis. To quantify the nutrient distribution by CMNs to the host and neighboring plants, we used ¹⁵ N labeling. Growth and ¹⁵ N concentrations of C. australis and T. pratense were measured, as well the arbuscular mycorrhizal fungi-colonization rates of T. pratense. We found that parasitism by C. australis reduced the biomass of T. pratense. In the absence of the parasite, CMNs increased the ¹⁵ N concentration of both T. pratense plants, but did not affect their biomass. However, with the parasite, the difference between host and neighboring T. pratense plants in ¹⁵ N concentration and biomass were amplified by CMNs. Furthermore, CMNs decreased the negative effect of C. australis on growth of the host T. pratense plants. Finally, although CMNs did not influence the ¹⁵ N concentration of C. australis, they reduced its biomass. Our results indicate that when T. pratense was parasitized by C. australis, CMNs preferentially distributed more mineral nutrients to the nonparasitized neighboring T. pratense plant, and that this had a negative feedback on the growth of the parasite.

Enhancing Water Harvesting through the Cascading Effect

Harvesting water from high humidity conditions is an attractive strategy toward strengthening water security due to its cost-effective and zero-energy mechanism. To facilitate this process, bio-inspired microstructures with heightened water accumulating ability are typically affixed onto atmospheric water harvesters. However, because of this surface morphology type harvester design, there is an inherent partition of regions with different water accumulating abilities: the active water harvesting region (AWHR) and passive water harvesting region (PWHR). Most of the water harvested by such water harvesters is usually attributed to the AWHR, while a large amount of uncollected water is present in the PWHR as numerous small water droplets that are prone to re-evaporation. This lack of PWHR utilization may be considered as the Achilles' heel toward optimal water harvesting. Hence, in this work, a cascading effect was proposed with a microstructure design to induce water harvesting from both AWHR and PWHR. The "clearing" of PWHR columns was demonstrated via a cascading effect, contributing to ca. 3 times more water harvested as compared to the unmodified water harvester. The successful demonstration of this cascading effect highlights the necessity of considering PWHR in the future water harvester designs so as to achieve efficient water harvesting.

Design of Small Nanoparticles Decorated with Amphiphilic Ligands: Self-Preservation Effect and Translocation into a Plasma Membrane

Design of nanoparticles (NPs) for biomedical applications requires a thorough understanding of cascades of nano-bio interactions at different interfaces. Here, we take into account the cascading effect of NP functionalization on interactions with target cell membranes by determining coatings of biomolecules in biological media. Cell culture experiments show that NPs with more hydrophobic surfaces are heavily ingested by cells in both the A549 and HEK293 cell lines. However, before reaching the target cell, both the identity and amount of recruited biomolecules can be influenced by the pristine NPs' hydrophobicity. Dissipative particle dynamics (DPD) simulations show that hydrophobic NPs acquire coatings of more biomolecules, which may conceal the properties of the as-engineered NPs and impact the targeting specificity. Based on these results, we propose an amphiphilic ligand coating on NPs. DPD simulations reveal the design principle, following which the amphiphilic ligands first curl in solvent to reduce the surface hydrophobicity, thus suppressing the assemblage of biomolecules. Upon attaching to the membrane, the curled ligands extend and rearrange to gain contacts with lipid tails, thus dragging NPs into the membrane for translocation. Three NP-membrane interaction states are identified that are found to depend on the NP size and membrane surface tension. These results can provide useful guidelines to fabricate ligand-coated NPs for practical use in targeted drug delivery, and motivate further studies of nano-bio-interactions with more consideration of cascading effects.

Interactions among predators and plant specificity protect herbivores from top predators

The worldwide loss of top predators from natural and agricultural systems has heightened the need to understand how important they are in controlling herbivore abundance. The effect of top predators on herbivore species is likely to depend on (1) the importance of the consumption of intermediate predators by top predators (intra-guild predation; IGP), but also on (2) plant specificity by herbivores, because specialists may defend themselves better (enemy-free space; EFS). Insectivorous birds, as top predators, are generally known to effectively control herbivorous insects, despite also consuming intermediate predators such as spiders, but how this effect varies among herbivore species in relation to the cascading effects of IGP and EFS is not known. To explore this, we excluded birds from natural fynbos vegetation in South Africa using large netted cages and recorded changes in abundance relative to control plots for 199 plant-dwelling intermediate predator and 341 herbivore morpho-species that varied in their estimated plant specificity. We found a strong negative effect of birds on the total abundance of all intermediate predators, with especially clear effects on spiders (strong IGP). In contrast with previous studies, which document a negative effect of birds on herbivores, we found an overall neutral effect of birds on herbivore abundance, but the effect varied among species: some species were negatively affected by birds, suggesting that they were mainly consumed by birds, whereas others, likely released from spiders by IGP, were positively affected. Some species were also effectively neutrally affected by birds. These tended to be more specialized to plants compared to the other species, which may imply that some plant specialists benefited from protection provided by EFS from both birds and spiders. These results suggest that the response of herbivore species to top predators may depend on cascading effects of interactions among predators and on their degree of plant specificity.

Long-term trends in trait structure of riverine communities facing predation risk increase and trophic resource decline

Many large European rivers have undergone multiple pressures that have strongly impaired ecosystem functioning at different spatial and temporal scales. Global warming and other environmental changes have favored the success of invasive species, deeply modifying the structure of aquatic communities in large rivers. Some exogenous species could alter trophic interactions within assemblages by increasing the predation risk for potential prey species (top-down effect) and limiting the dynamics of others via resource availability limitation (bottom-up effect). Furthermore, large transboundary rivers are complex aquatic ecosystems that have often been poorly investigated so that data for assessing long-term ecological trends are missing. In this study, we propose an original approach for investigating long-term combined effects of global warming, trophic resource decrease, predation risk, and water quality variations on the trait-based structure of macroinvertebrate and fish assemblages over 26 yr (1985-2011) and 427-km stretch of the river Meuse (France and Belgium). The study of temporal variations in biological, physiological, and ecological traits of macroinvertebrate and fish allowed identifying community trends and distinguishing impacts of environmental perturbations from those induced by biological alterations. We provide evidence, for this large European river, of an increase in water temperature (close to 1°C) and a decrease in phytoplankton biomass (-85%), as well as independent effects of these changes on both invertebrate and fish communities. The reduction of trophic resources in the water column by invasive molluscs has dramatically affected the density of omnivorous fish in favor of invertebrate feeders, while scrapers became the major feeding guild among invertebrates. Macroinvertebrate and fish communities have shifted from large-sized organisms with low fecundity to prolific, small-sized organisms, with early maturity, as a response to increased predation pressure.