Context-dependent Responses Research Articles

MAIT cells: Conserved watchers on the wall.

MAIT cells are innate-like T cells residing in barrier tissues such as the lung, skin, and intestine. Both the semi-invariant T cell receptor of MAIT cells and the restricting element MR1 are deeply conserved across mammals, indicating non-redundant functions linked to antigenic specificity. MAIT cells across species concomitantly express cytotoxicity and tissue-repair genes, suggesting versatile functions. Accordingly, MAIT cells contribute to antibacterial responses as well as to the repair of damaged barrier tissues. MAIT cells recognize riboflavin biosynthetic pathway-derived metabolites, which rapidly cross epithelial barriers to be presented by antigen-presenting cells. Changes in gut ecology during intestinal inflammation drive the expansion of strong riboflavin and MAIT ligand producers. Thus, MAIT cells may enable real-time surveillance of microbiota dysbiosis across intact epithelia and provide rapid and context-dependent responses. Here, we discuss recent findings regarding the origin and regulation of MAIT ligands and the role of MAIT cells in barrier tissues. We speculate on the potential reasons for MAIT cell conservation during evolution.

Specific retinal neurons regulate context-dependent defensive responses to visual threat.

While encountering a visual threat, an animal assesses multiple factors to choose an appropriate defensive strategy. For example, when a rodent detects a looming aerial predator, its behavioral response can be influenced by a specific environmental context, such as the availability of a shelter. Indeed, rodents typically escape from a looming stimulus when a shelter is present; otherwise, they typically freeze. Here we report that context-dependent behavioral responses can be initiated at the earliest stage of the visual system by distinct types of retinal ganglion cells (RGCs), the retina's output neurons. Using genetically defined cell ablation in mature mice, we discovered that some RGC types were necessary for either escaping (alpha RGCs) or freezing (intrinsically photosensitive RGCs) in response to a looming stimulus but not for both behaviors; whereas other RGC types were not required for either behavior (direction-selective RGCs preferring vertical motion). Altogether, our results suggest that specific RGC types regulate distinct behavioral responses elicited by the same threatening stimulus depending on contextual signals in the environment. These findings emphasize the unique contribution of early visual pathways to evolutionally conserved behavioral reactions.

Exposure to calls before hatching affects the post-hatching behaviour of domestic chickens.

The soundscape experienced by animals early in life can affect their behaviour later in life. For birds, sounds experienced in the egg can influence how individuals learn to respond to specific calls post-hatching. However, how early acoustic experiences affect subsequent social behaviour remains unknown. Here, we investigate how exposure to maternal 'cluck' calls pre-hatching affects the behaviour of domestic chickens (Gallus gallus domesticus) at 3-5 days and 17-21 days old. We incubated eggs and played cluck calls to half of them. After hatching, we raised chicks in small groups occupying different enclosures. At 3-5 days old, we tested chicks' responses to three stimuli: (i) background sound, (ii) chick calls and (iii) cluck calls. We found that the pre-hatching experience of cluck calls reduced the likelihood of moving in response to all three stimuli. At 17-21 days old, some chicks explored beyond their own enclosure and 'visited' other groups. Chicks exposed to cluck calls before hatching were three times more likely to enter another group's enclosure than control chicks, and this was unaffected by the chicks' social connectedness. Our results indicate age- and context-dependent responses of chicks to pre-hatching cluck-call playbacks, with potential long-term effects on individual social behaviour.

Systematic Evaluation of Biotic and Abiotic Factors in Antifungal Microorganism Screening.

Microorganisms have significant potential to control fungal contamination in various foods. However, the identification of strains that exhibit robust antifungal activity poses challenges due to highly context-dependent responses. Therefore, to fully exploit the potential of isolates as antifungal agents, it is crucial to systematically evaluate them in a variety of biotic and abiotic contexts. Here, we present an adaptable and scalable method using a robotic platform to study the properties of 1022 isolates obtained from maple sap. We tested the antifungal activity of isolates alone or in pairs on M17 + lactose (LM17), plate count agar (PCA), and sucrose-allantoin (SALN) culture media against Kluyveromyces lactis, Candida boidinii, and Saccharomyces cerevisiae. Microorganisms exhibited less often antifungal activity on SALN and PCA than LM17, suggesting that the latter is a better screening medium. We also analyzed the results of ecological interactions between pairs. Isolates that showed consistent competitive behaviors were more likely to show antifungal activity than expected by chance. However, co-culture rarely improved antifungal activity. In fact, an interaction-mediated suppression of activity was more prevalent in our dataset. These findings highlight the importance of incorporating both biotic and abiotic factors into systematic screening designs for the bioprospection of microorganisms with environmentally robust antifungal activity.

Targeting SEZ6L2 in Colon Cancer: Efficacy of Bexarotene and Implications for Survival.

Bexarotene, also recognized as Targretin, is categorized as a retinoid, a type of cancer drug. Nevertheless, the precise mechanisms of bexarotene in relation to colon cancer remain unclear. In colon cancer, SEZ6L2 was suggested as one of the biomarkers and targets. This study presents a comprehensive exploration of the role of SEZ6L2 in colon cancer. We utilized both TCGA data and a cohort of Chinese patients. In a meticulous analysis of 478 colon cancer cases, SEZ6L2 expression levels were examined in relation to clinical characteristics, staging parameters, and treatment outcomes. Additionally, we investigated the pharmacological impact of bexarotene on SEZ6L2, demonstrating a significant downregulation of SEZ6L2 at both mRNA and protein levels in colon cancer patients following bexarotene treatment. SEZ6L2 consistently overexpresses in colon cancer, serving as a potential universal biomarker with prognostic significance, validated in a diverse Chinese cohort. In vitro, SEZ6L2 promotes cell viability without affecting migration. Bexarotene treatment inhibits SEZ6L2 expression, correlating with reduced viability both in vitro and in vivo. SEZ6L2 overexpression accelerates declining survival rates in an in vivo context. Bexarotene's efficacy is context-dependent, effective in parental cells but not with SEZ6L2 overexpression. Computational predictions suggest a direct SEZ6L2-bexarotene interaction, warranting further experimental exploration. The study provides valuable insights into SEZ6L2 as a prognostic biomarker in colon cancer, revealing its intricate relationship with clinical parameters, treatment outcomes, and bexarotene effects. Context-dependent therapeutic responses emphasize the nuanced understanding required for SEZ6L2's role in colon cancer, paving the way for targeted therapeutic strategies.

Disturbance-mediated changes to boreal mammal spatial networks in industrializing landscapes.

Compound effects of anthropogenic disturbances on wildlife emerge through a complex network of direct responses and species interactions. Land-use changes driven by energy and forestry industries are known to disrupt predator-prey dynamics in boreal ecosystems, yet how these disturbance effects propagate across mammal communities remains uncertain. Using structural equation modeling, we tested disturbance-mediated pathways governing the spatial structure of multipredator multiprey boreal mammal networks across a landscape-scale disturbance gradient within Canada's Athabasca oil sands region. Linear disturbances had pervasive direct effects, increasing site use for all focal species, except black bears and threatened caribou, in at least one landscape. Conversely, block (polygonal) disturbance effects were negative but less common. Indirect disturbance effects were widespread and mediated by caribou avoidance of wolves, tracking of primary prey by subordinate predators, and intraguild dependencies among predators and large prey. Context-dependent responses to linear disturbances were most common among prey and within the landscape with intermediate disturbance. Our research suggests that industrial disturbances directly affect a suite of boreal mammals by altering forage availability and movement, leading to indirect effects across a range of interacting predators and prey, including the keystone snowshoe hare. The complexity of network-level direct and indirect disturbance effects reinforces calls for increased investment in addressing habitat degradation as the root cause of threatened species declines and broader ecosystem change.

Context-dependent responses to geopolitical risk in Middle Eastern and African stock markets: An asymmetric volatility spillover study

This paper examines the asymmetric volatility spillover impact of geopolitical risk on stock market returns across six Middle Eastern and African (MEA) economies: Egypt, Israel, Saudi Arabia, Tunisia, Turkey, and South Africa. Using the asymmetric MGARCH (Multivariate GARCH) model of BEKK (Baba, Engle, Kraft, and Kroner), the study identifies different responses to geopolitical risk (GPR) index in these markets and its division into act- and threat-related components. The results show that the susceptibility and responses to these risks are highly context-dependent, reflecting the unique economic and geopolitical structures of each market. Moreover, these economies exhibit an asymmetric response to geopolitical risk, highlighting the importance of not only the magnitude but also the direction of these risks. The study underscores the need for investors to adopt a nuanced view of geopolitical risk and its multifaceted impacts on different markets. These findings hold valuable implications for investment decisions and policy-making in these economies.

Structural variants of Bacteroides fragilis-derived alpha-galactosylceramides induce unique natural killer T cell responses.

Abstract Natural killer T (NKT) cell is a unique subset of thymus-derived T cells that recognizes glycolipids presented by CD1d molecule expressed on antigen-presenting cells. The most studied agonistic antigen of NKT cells is alpha-galactosylceramide (αGC). It has been shown that structural features of lipid antigens determine distinct NKT cell responses. In order to drive context-dependent NKT cell responses, understanding the structural characteristics of lipid antigens is important. In the previous study, we have shown that human gut symbiont Bacteroides fragilis (B.fragilis) uniquely produces αGCs (BfaGC), which can normalize the overproliferation of neonatal colonic NKT cells in germ-free mice, and chemically-synthesized structural isomers of BfaGCs induce structure-specific NKT cell responses. In this study, to further investigate the essential structural moiety of BfaGC for the unique immunomodulatory activity, we synthesized BfaGC analogues by modifying their chain lengths and functional groups. We have examined how the analogues differently stimulate NKT cells by analyzing in vitro cytokine production, NKT cell proliferation and effect on specific NKT cell subpopulations. We found the critical features and functional groups on the BfaGC structure leading to immunomodulatory responses. It is expected that our findings may advance further development of lipid antigens to fine-tune context-specific NKT cell responses in immunological diseases.

Context-dependent multimodal behaviour in a coral reef fish.

Animals are expected to respond flexibly to changing circumstances, with multimodal signalling providing potential plasticity in social interactions. While numerous studies have documented context-dependent behavioural trade-offs in terrestrial species, far less work has considered such decision-making in fish, especially in natural conditions. Coral reef ecosystems host 25% of all known marine species, making them hotbeds of competition and predation. We conducted experiments with wild Ambon damselfish (Pomacentrus amboinensis) to investigate context-dependent responses to a conspecific intruder; specifically, how nest defence is influenced by an elevated predation risk. We found that nest-defending male Ambon damselfish responded aggressively to a conspecific intruder, spending less time sheltering and more time interacting, as well as signalling both visually and acoustically. In the presence of a model predator compared to a model herbivore, males spent less time interacting with the intruder, with a tendency towards reduced investment in visual displays compensated for by an increase in acoustic signalling instead. We therefore provide ecologically valid evidence that the context experienced by an individual can affect its behavioural responses and multimodal displays towards conspecific threats.

The adaptive immune response to Trichuris in wild versus laboratory mice: An established model system in context.

Laboratory model organisms have provided a window into how the immune system functions. An increasing body of evidence, however, suggests that the immune responses of naive laboratory animals may differ substantially to those of their wild counterparts. Past exposure, environmental challenges and physiological condition may all impact on immune responsiveness. Chronic infections of soil-transmitted helminths, which we define as establishment of adult, fecund worms, impose significant health burdens on humans, livestock and wildlife, with limited treatment success. In laboratory mice, Th1 versus Th2 immune polarisation is the major determinant of helminth infection outcome. Here we compared antigen-specific immune responses to the soil-transmitted whipworm Trichuris muris between controlled laboratory and wild free-ranging populations of house mice (Mus musculus domesticus). Wild mice harbouring chronic, low-level infections produced lower levels of cytokines in response to Trichuris antigen than laboratory-housed C57BL/6 mice. Wild mouse effector/memory CD4+ T cell phenotype reflected the antigen-specific cytokine response across the Th1/Th2 spectrum. Increasing egg shedding was associated with body condition loss. However, local Trichuris-specific Th1/Th2 balance was positively associated with worm burden only in older wild mice. Thus, although the fundamental relationships between the CD4+ T helper cell response and resistance to T. muris infection are similar in both laboratory and wild M. m. domesticus, there are quantitative differences and age-specific effects that are analogous to human immune responses. These context-dependent immune responses demonstrate the fundamental importance of understanding the differences between model and natural systems for translating mechanistic models to 'real world' immune function.

Chinese Outbound Tourists and the Changing Political Economies of Cambodia, Malaysia, and Singapore

ABSTRACT The global tourism industry was severely affected by the COVID-19 pandemic. New economic, social and political realities have emerged, and destinations are facing the changes. This research compares three popular destinations among Chinese tourists (i.e. Cambodia, Malaysia and Singapore) to illuminate key political economic shifts of tourism in Southeast Asia in relation to China amid of the unfolding ‘new normal.’ By conducting a qualitative review and content analysis on publicly available data (e.g. media stories and public documents), the article contributes to a burgeoning body of knowledge on the impact of the pandemic wipe-out of the tourism industry and the context-dependent responses across destinations. The study reveals that established attitudes toward tourism have been challenged, as China and its major host countries learn to live with a weakened tourism industry. Whilst the three countries attempt to diversify their tourism economy, their dependency on the Chinese in their tourism and economic development will possibly deepen even though the post-Covid Chinese economy has slowed down. The comparison illustrates the different types of China-driven forces affecting these countries, highlighting the nuances and shades of understanding tourism political economies in these Southeast Asian countries.

Facilitation: Isotopic evidence that wood-boring beetles drive the trophic diversity of secondary decomposers

Deadwood heterogeneity is regarded as a primary causal driver of deadwood-associated soil biodiversity, but the underlying mechanisms remain elusive. This is partly due to the technical difficulties in disentangling and quantifying different components (e.g., deadwood is both habitat and food) of heterogeneity to which soil organisms may have context-dependent responses. Furthermore, non-trophic interactions, e.g., facilitation, also add complexity to deadwood heterogeneity-biodiversity relationships, yet their influences are unaccounted for in most deadwood biodiversity studies. To address these research gaps, we sampled isopod communities from 40 logs of two isotopically distinct tree species, which had been cut and incubated reciprocally for eight years in each of two environmentally contrasting sites (e.g., differences in background isotopic signatures and litter turnover rates). We then assessed the extent to which the variation in the biodiversity of isopod communities is explained by deadwood heterogeneity induced by wood-boring beetles. Stable isotope ratios (i.e., δ13C and δ15N) were employed to examine the response of trophic diversity of isopod communities to the rarely tested food facet of deadwood heterogeneity. We hypothesized the deadwood heterogeneity is boosted by wood-boring beetles and thereby positively affects the abundance, taxonomic diversity and trophic diversity of isopod communities. Our results supported this hypothesis: the abundance and Shannon and Simpson diversity as well as trophic diversity of isopods were positively correlated to wood-boring beetle tunnel densities in both sites and across the two tree species. We observed significant tree species and reciprocal treatment effects on the δ15N values of isopods in one of the two sites. This result suggested that the use of deadwood as food sources versus habitats by isopods is environmentally dependent. This study demonstrates that there is substantial heterogeneity within deadwood that promotes the diversity and trophic diversity of macroinvertebrates. This relationship is mediated by saproxylic beetle facilitation, with implications for the roles of saproxylic beetles and within-deadwood heterogeneity in determining microbial wood decomposition in temperate forests.

Trait-mediated processes and per capita contributions to ecosystem functioning depend on conspecific density and climate conditions

The ecological consequences of environmental change are highly dependent on the functional contributions of the surviving community, but categorical descriptors commonly used to project ecosystem futures fail to capture context dependent response variability. Here, we show that intraspecific variability for a range of sediment-dwelling marine invertebrates is moderated by changes in the density of conspecifics and/or climatic conditions. Although these trait-mediated changes result in modifications to ecosystem properties, we find that the contributions of individuals to functioning are not necessarily additive but, instead, are a result of alterations to per capita performance. Our findings also indicate that trait variation within species can exert a greater influence on functioning than that of trait variation between species. Hence, projections of likely functional outcomes that scale from mean trait values are unlikely to be robust, highlighting a need to account for how and when intraspecific variability results in context-dependent community responses to change.

Large Language Model (LLM)-Powered Chatbots Fail to Generate Guideline-Consistent Content on Resuscitation and May Provide Potentially Harmful Advice.

Innovative large language model (LLM)-powered chatbots, which are extremely popular nowadays, represent potential sources of information on resuscitation for the general public. For instance, the chatbot-generated advice could be used for purposes of community resuscitation education or for just-in-time informational support of untrained lay rescuers in a real-life emergency. This study focused on assessing performance of two prominent LLM-based chatbots, particularly in terms of quality of the chatbot-generated advice on how to give help to a non-breathing victim. In May 2023, the new Bing (Microsoft Corporation, USA) and Bard (Google LLC, USA) chatbots were inquired (n = 20 each): "What to do if someone is not breathing?" Content of the chatbots' responses was evaluated for compliance with the 2021 Resuscitation Council United Kingdom guidelines using a pre-developed checklist. Both chatbots provided context-dependent textual responses to the query. However, coverage of the guideline-consistent instructions on help to a non-breathing victim within the responses was poor: mean percentage of the responses completely satisfying the checklist criteria was 9.5% for Bing and 11.4% for Bard (P >.05). Essential elements of the bystander action, including early start and uninterrupted performance of chest compressions with adequate depth, rate, and chest recoil, as well as request for and use of an automated external defibrillator (AED), were missing as a rule. Moreover, 55.0% of Bard's responses contained plausible sounding, but nonsensical guidance, called artificial hallucinations, that create risk for inadequate care and harm to a victim. The LLM-powered chatbots' advice on help to a non-breathing victim omits essential details of resuscitation technique and occasionally contains deceptive, potentially harmful directives. Further research and regulatory measures are required to mitigate risks related to the chatbot-generated misinformation of public on resuscitation.

Light pollution in complex ecological systems.

Light pollution has emerged as a burgeoning area of scientific interest, receiving increasing attention in recent years. The resulting body of literature has revealed a diverse array of species-specific and context-dependent responses to artificial light at night (ALAN). Because predicting and generalizing community-level effects is difficult, our current comprehension of the ecological impacts of light pollution on complex ecological systems remains notably limited. It is critical to better understand ALAN's effects at higher levels of ecological organization in order to comprehend and mitigate the repercussions of ALAN on ecosystem functioning and stability amidst ongoing global change. This theme issue seeks to explore the effects of light pollution on complex ecological systems, by bridging various realms and scaling up from individual processes and functions to communities and networks. Through this integrated approach, this collection aims to shed light on the intricate interplay between light pollution, ecological dynamics and humans in a world increasingly impacted by anthropogenic lighting. This article is part of the theme issue 'Light pollution in complex ecological systems'.

A thalamic-hippocampal CA1 signal for contextual fear memory suppression, extinction, and discrimination

The adaptive regulation of fear memories is a crucial neural function that prevents inappropriate fear expression. Fear memories can be acquired through contextual fear conditioning (CFC) which relies on the hippocampus. The thalamic nucleus reuniens (NR) is necessary to extinguish contextual fear and innervates hippocampal CA1. However, the role of the NR-CA1 pathway in contextual fear is unknown. We developed a head-restrained virtual reality CFC paradigm, and demonstrate that mice can acquire and extinguish context-dependent fear responses. We found that inhibiting the NR-CA1 pathway following CFC lengthens the duration of fearful freezing epochs, increases fear generalization, and delays fear extinction. Using in vivo imaging, we recorded NR-axons innervating CA1 and found that NR-axons become tuned to fearful freezing following CFC. We conclude that the NR-CA1 pathway actively suppresses fear by disrupting contextual fear memory retrieval in CA1 during fearful freezing behavior, a process that also reduces fear generalization and accelerates extinction.

Interplays between cis- and trans-Acting Factors for Alternative Splicing in Response to Environmental Changes during Biological Invasions of Ascidians.

Alternative splicing (AS), a pivotal biological process contributing to phenotypic plasticity, creates a bridge linking genotypes with phenotypes. Despite its importance, the AS mechanisms underlying environmental response and adaptation have not been well studied, and more importantly, the cis- and trans-acting factors influencing AS variation remain unclear. Using the model invasive congeneric ascidians, Ciona robusta, and Ciona savignyi, we compared their AS responses to environmental changes and explored the potential determinants. Our findings unveiled swift and dynamic AS changes in response to environmental challenges, and differentially alternative spliced genes (DASGs) were functionally enriched in transmembrane transport processes. Interestingly, both the prevalence and level of AS in C. robusta were lower than those observed in C. savignyi. Furthermore, these two indices were higher under temperature stresses compared to salinity stresses in C. savignyi. All the observed patterns underscore the species-specific and environmental context-dependent AS responses to environmental challenges. The dissimilarities in genomic structure and exon/intron size distributions between these two species likely contributed to the observed AS variation. Moreover, we identified a total of 11 and 9 serine/arginine-rich splicing factors (SRSFs) with conserved domains and gene structures in the genomes of C. robusta and C. savignyi, respectively. Intriguingly, our analysis revealed that all detected SRSFs did not exhibit prevalent AS regulations. Instead, we observed AS control over a set of genes related to splicing factors and spliceosome components. Altogether, our results elucidate species-specific and environmental challenge-dependent AS response patterns in closely related invasive ascidians. The identified splicing factors and spliceosome components under AS control offer promising candidates for further investigations into AS-mediated rapid responses to environmental challenges complementary to SRSFs.

AI on the street: Context-dependent responses to artificial intelligence

As artificial intelligence (AI) applications proliferate, their creators seemingly anticipate that users will make similar trade-offs between costs and benefits across various commercial and public applications, due to the technological similarity of the provided solutions. With a multimethod investigation, this study reveals instead that users develop idiosyncratic evaluations of benefits and costs depending on the context of AI implementation. In particular, the tensions that drive AI adoption depend on perceived personal costs and choice autonomy relative to the perceived (personal vs. societal) benefits. The tension between being served rather than exploited is lowest for public AI directed at infrastructure (cf. commercial AI), due to lower perceived costs. Surveillance AI evaluations are driven by fears beyond mere privacy breaches, which overcome the societal and safety benefits. Privacy-breaching applications are more acceptable when public entities implement them (cf. commercial). The authors provide guidelines for public policy and AI practitioners, based on how consumers trade off solutions that differ in their benefits, costs, data transparency, and privacy enhancements.

Context-dependent responses of terrestrial invertebrates to anthropogenic nitrogen enrichment: A meta-analysis.

Anthropogenic increases in nitrogen (N) concentrations in the environment are affecting plant diversity and ecosystems worldwide, but relatively little is known about N impacts on terrestrial invertebrate communities. Here, we performed an exploratory meta-analysis of 4365 observations from 126 publications reporting on the richness (number of taxa) or abundance (number of individuals per taxon) of terrestrial arthropods or nematodes in relation to N addition. We found that the response of invertebrates to N enrichment is highly dependent on both species' traits and local climate. The abundance of arthropods with incomplete metamorphosis, including agricultural pest species, increased in response to N enrichment. In contrast, arthropods exhibiting complete or no metamorphosis, including pollinators and detritivores, showed a declining abundance trend with increasing N enrichment, particularly in warmer climates. These contrasting and context-dependent responses may explain why we detected no overall response of arthropod richness. For nematodes, the abundance response to N enrichment was dependent on mean annual precipitation and varied between feeding guilds. We found a declining trend in abundance with N enrichment in dry areas and an increasing trend in wet areas, with slopes differing between feeding guilds. For example, at mean levels of precipitation, bacterivore abundance showed a positive trend in response to N addition while fungivore abundance declined. We further observed an overall decline in nematode richness with N addition. These N-induced changes in invertebrate communities could have negative consequences for various ecosystem functions and services, including those contributing to human food production.

An integrative view of human hippocampal function: Differences with other species and capacity considerations.

We describe an integrative model that encodes associations between related concepts in the human hippocampal formation, constituting the skeleton of episodic memories. The model, based on partially overlapping assemblies of "concept cells," contrast markedly with the well-established notion of pattern separation, which relies on conjunctive, context dependent single neuron responses, instead of the invariant, context independent responses found in the human hippocampus. We argue that the model of partially overlapping assemblies is better suited to cope with memory capacity limitations, that the finding of different types of neurons and functions in this area is due to a flexible and temporary use of the extraordinary machinery of the hippocampus to deal with the task at hand, and that only information that is relevant and frequently revisited will consolidate into long-term hippocampal representations, using partially overlapping assemblies. Finally, we propose that concept cells are uniquely human and that they may constitute the neuronal underpinnings of cognitive abilities that are much further developed in humans compared to other species.