Biology subjects

Bhattacharjee, D.

Publications and source records attributed to Bhattacharjee, D..

At least 19 recordsLinked to original sources

bioRxiv2026

Drivers of space use in a large semi-urban feral ungulate under seasonally fluctuating resource conditions

Resource scarcity prompts animals to adjust their space use in ways that enhance their survival. In wild herbivores, seasonal habitat shifts are well studied; however, little is known about how large herbivores navigate human-dominated landscapes under fluctuating resource conditions. In Hong Kong, feral water buffalo (Bubalus bubalis; henceforth buffalo) experience declines in body condition score during the dry season. While buffalo expand spatial ranges in the dry season, whether this expansion reflects access to improved ecological conditions, and how key anthropogenic factors (like distance to roads and human density) further influence space use, remains understudied. We observed six buffalo herds (n=92 known individuals) across one wet (July-September 2023) and one dry (January-March 2024) season. We recorded herd locations and extracted remotely sensed habitat and environmental data. We used Normalized Difference Vegetation Index (NDVI) as a proxy of vegetation productivity and included elevation, distance to roads, and human density as additional predictors. We hypothesized that dry-season space use would shift toward higher vegetation productivity, and that anthropogenic factors would have weak influence on space use due to the adaption of buffalo in human-dominated landscapes. We found that buffalo used areas with higher vegetation productivity and higher elevation in the dry season than in the wet. Distance to roads and human density had no detectable effect. Our findings reveal that space use by a large herbivore like buffalo in human-dominated landscapes is strategic and resource driven, and that these seasonal shifts may have important implications for local biodiversity and human-animal interactions.

zoology↗

bioRxiv2026

Dual role of the OMM E3 Ub ligase MARCH5 in de novo peroxisome biogenesis and mitochondrial quality control through direct regulation of Pex26.

Recent evidence indicates that mitochondria, through the activity of the E3 Ub ligase MARCH5, are critical for de novo peroxisome biogenesis. Here we report that peroxisome biogenesis factor Pex26 is a MARCH5 client protein. In peroxisome-containing cells, MARCH5 interacts with Pex26 and facilitates the transfer of newly synthesized Pex26 from the OMM to peroxisomes. MARCH5 also controls peroxisomal delivery of other candidate peroxins in peroxisome-containing cells. On the other hand, in peroxisome-deficient cells, the turnover rate of Pex26 is dramatically increased, and MARCH5 targets this protein for p97-dependent proteasomal degradation. Both activities are mediated by MARCH5-dependent Pex26 ubiquitination. Knockout of Pex26 induces the accumulation of cells containing Tom20-positive, Catalase-deficient pre-peroxisomes. Further supporting the critical role of MARCH5 in peroxisome biogenesis, these structures are absent in Pex26/MARCH5 double knockout cells. The data support the model, where in peroxisome-containing cells, MARCH5 acts as a peroxisome biogenesis factor, while with defective peroxisome biogenesis, as in Zellweger syndrome cells, it protects mitochondria from potentially toxic accumulation of peroxins on the OMM.

cell biology↗

bioRxiv2025

A clinical-stage oncology compound selectively targets drug-resistant cancers

Re-evaluating existing clinical compounds can uncover previously unrecognized mechanisms that reshape a drugs therapeutic potential. The small molecule Procaspase-Activating Compound 1 (PAC-1) entered oncology testing as a proposed activator of caspase-driven apoptosis. Here, we show that PAC-1-driven cytotoxicity occurs in the absence of executioner caspase expression, demonstrating that its anti-cancer activity occurs via an alternative mechanism. We provide genetic, biochemical, and biophysical evidence demonstrating that PAC-1 functions as a highly selective iron chelator that eliminates cancer cells by disrupting iron homeostasis. Unexpectedly, we discovered that expression of the key chemotherapy-resistance pump MDR1 confers marked hypersensitivity to PAC-1 treatment. While PAC-1 is only weakly effluxed by MDR1 under basal conditions, this process is potentiated when PAC-1 is bound to iron. Consequently, PAC-1 induces progressive iron depletion and selective cytotoxicity in otherwise drug-resistant MDR1-expressing cancer cells. Together, these findings redefine PAC-1s mechanism-of-action and establish a framework for exploiting multidrug resistance as a therapeutic vulnerability through targeted iron starvation.

cancer biology↗

bioRxiv2025

Social status predicts self-directed behaviors, contingent on broader social dynamics

Emotional states like anxiety are adaptive, assisting individuals during social uncertainty and threats. While humans can self-report anxiety, assessing comparable states in animals requires objective measures. Self-directed behaviours (SDBs), including self-scratch, autogroom, and yawn, are indicators of anxiety, particularly in nonhuman primates. Yet it is unclear whether they reflect a common underlying process or distinct responses shaped by demography, social interactions and status, and the broader social dynamics. We studied 13 macaque groups across six species along a despotic-egalitarian social style gradient to investigate the factors associated with variation in SDBs. Our findings revealed partial correlational consistency among the SDBs, where only self-scratch and autogroom positively correlated. Further, we found that males yawned more than females, and individuals receiving less aggression exhibited longer autogroom bouts. Dominance rank showed behaviour-specific effects, with weak evidence for an association with self-scratch, longer autogrooming in subordinates, and a non-linear pattern in yawning, which was lowest at intermediate ranks. Alpha status was linked to more frequent yawning than others. And finally, social style showed no consistent effects on SDBs. Our research demonstrates that SDBs in macaques reflect differential responses related to social uncertainty rather than one anxiety dimension, providing insights into primate emotion regulation.

animal behavior and cognition↗

bioRxiv2025

Reliability and precision of thermal imaging measurements to study animal behaviour and welfare

The use of infrared thermal imaging has become increasingly popular in animal behaviour, health, and welfare research over the last decade. Yet, there is a lack of consensus regarding how this technique should be best applied when measuring peripheral temperatures in animals, including which regions of interest to favour. This fundamental issue necessitates checking the reliability and precision of thermal imaging data when taking repeated measurements, both over short and relatively long time windows. Using goats (Capra hircus) as a model, we investigated two subcategories of reliability, short-term repeatability (measurements taken in the same session) and reproducibility (over multiple sessions), as well as the precision of surface temperatures in two facial regions. We collected data from 20 goats over five measurement sessions over consecutive days. During each session, five frames were collected from approximately one-minute-long videos. From each video, we extracted the mean, maximum, and minimum surface temperatures from the left eye, right eye, and nose tip. To calculate repeatability, we compared temperature variation attributed to differences between goats against total variation in surface temperatures measured in a single session. We defined precision as the temperature deviation within which the mean temperature measured from one to five thermal images was expected to fall in relation to the mean of five image replicates 95% of the time. Reproducibility was investigated by comparing variation attributed to differences in temperature between measurement sessions against total variation in surface temperatures. Our results revealed that repeatability and precision of mean and maximum temperatures across five repeated measurements were high for all facial regions, with between 93.50% and 99.81% of total temperature variation attributable to the individual goat tested. Conversely, minimum temperatures were more variable, less repeatable, and less precise. For reproducibility, measurement sessions accounted for a high proportion of variation in nasal temperatures (74.61-85.85%), and a lower, but substantial proportion of eye temperature variation (49.59-67.01%). We conclude that mean and maximum thermal measures show promise for quantifying nasal and eye temperatures in the short term. However, surface temperature measured across several days was not readily comparable, highlighting the importance of considering ambient conditions in thermal imaging research. Overall, this study provides valuable insights into the appropriate use of thermal imaging in goats and, more broadly, animal behaviour and welfare research.

animal behavior and cognition↗

bioRxiv2025

Diversity and prevalence of Anaerostipes in the human gut microbiota

Members of the class Clostridia, a polyphyletic group of Gram-positive, spore-forming anaerobes in the Bacillota (Firmicutes) phylum, are prevalent and commonly associated with beneficial functions, such as providing colonization resistance against pathogens. Despite a demonstrated value in maintaining Clostridial populations in the gut, the functional and strain diversity of most commensal Clostridial species remains understudied. Here, we isolated and characterized Clostridial isolates, focusing on the genomic diversity of Anaerostipes, a prevalent butyrate-producing genus within the gut microbiota. We conducted a genomic comparison across 21 Anaerostipes strains isolated from healthy human fecal samples (n = 5) and publicly available genomes (n = 105). Whole genome comparisons across the Anaerostipes genus demonstrated 12 species bins, clustering into three major functionally distinct clusters correlating with host origin. One cluster (representing mostly A. caccae genomes) was distinguished by possessing a complete vitamin B12 biosynthesis pathway. Variability in carbohydrate and amino acid metabolism was demonstrated within dominant species of the human microbiota (A. hadrus, A. caccae, and A. hominis). Collectively, these data indicate metabolic variance across Anaerostipes species that may influence coexistence within the gut environment and variably influence health. IMPORTANCEAnaerostipes is a genus containing species known to produce butyrate upon fermenting lactate. Despite their association with health across studies using 16S rRNA gene-based analyses, little is known about genomic variability within and across species. Our study represents one of the first analyses to define strain variability across the Anaerostipes genus, identifying three functional clusters and close phylogenetic distance within species found in the human gut. Major variability within species prevalent in the human gut included variable carbohydrate and amino acid metabolism genes, suggesting the ability to coexist in the gut environment.

microbiology↗

bioRxiv2025

Despotism promotes cooperation through enhanced interdependencies in non-human primate societies

The evolutionary mechanisms of cooperation are well-studied, yet what motivates individuals to cooperate remains unclear. Although conventionally associated with enhanced social tolerance (self-domestication hypothesis) and prosociality (cooperative-breeding hypothesis), individuals belonging to species that are neither self-domesticated nor cooperatively-breeding also cooperate. An overarching interdependency hypothesis posits that inter-individual dependencies promote cooperation, but comparative evidence is lacking. We experimentally studied cooperation, prosociality, and tolerance in six macaque species along a despotic-egalitarian gradient. Within-group cooperation was higher in despotic than egalitarian societies yet restricted to few partners. Prosociality, kinship, and tolerance positively predicted cooperation success. Agent-based models consistently showed that despotic societies have fewer but more stable social bonds and, thus, higher interdependencies than egalitarian ones. Our results suggest that interdependencies facilitate the emergence and maintenance of cooperation.

animal behavior and cognition↗

bioRxiv2025

Adaptive behavioural strategies to seasonal challenges by a semi-urban feral ungulate

Seasonality, or temporal shifts between wet and dry seasons, profoundly affects the behavioural ecology of animals, particularly large herbivores, in (sub-) tropical climatic conditions. Behavioural strategies are crucial for overcoming challenges associated with seasonality. Group-level strategies to seasonality in the wild have received considerable attention, yet little is known about how large herbivores in human-dominated landscapes respond to seasonal challenges. Moreover, focusing solely on groups can obscure how individual animals of different sexes, ages, and personalities respond. We investigated a semi-urban feral population of a large ungulate, the water buffalo (Bubalus bubalis) (N=71) during a wet and a dry season. Individual body condition was non-invasively assessed to evaluate whether seasonality impacts physiology. To identify behavioural strategies, we collected data on feeding (grazing and browsing) and space use (core area and home range). Further, using a subset (n=30), we investigated the associations between personality and space use in the dry season. Body condition scores were highest during the wet season and then declined during the dry season, indicating an impact of seasonality on physiology. Older individuals were more affected than younger ones. Browsing increased during the dry compared to the wet season. While there was no change in core area use, home ranges expanded in the dry compared to the wet season. Regardless of season, females utilised home ranges larger than males. Females exhibiting higher social tension personalities had smaller core areas and home ranges than those with lower social tension. We show that buffalo employ behavioural strategies to overcome challenges associated with seasonality, and these strategies are contingent on intrinsic factors: sex, age, and personality. Our findings offer insights into the ecological principles -habitat use, resource utilisation, and competition- that govern the behavioural ecology of herbivores, and have implications for conservation and welfare in increasingly human-dominated and climate-sensitive landscapes.

zoology↗

bioRxiv2024

Personality assessment of synanthropic rhesus macaques: implications and challenges

"What makes animals thrive in human-dominated environments?" is a question that has been extensively researched transcending disciplines, but findings remain inconclusive. Consistent inter-individual differences or personalities can potentially explain the functional significance of habitat-specific traits and their variations that help animals successfully coexist with humans. Rhesus macaques (Macaca mulatta) are the most successful non-human primate in the Anthropocene, living in diverse climatic and environmental conditions. Studying the personalities of synanthropic rhesus macaques can provide insights into the biological traits that facilitate their success in human-dominated environments. We employed a multi-method bottom-up approach of behavioral observations and novelty experiments, standardized for assessing captive non-human primates, to evaluate the personalities of synanthropic adult rhesus macaques (N=52). To our surprise, novelty experiments encountered significant challenges, limiting their effectiveness. However, behavioral observations in the form of focal sampling revealed two repeatable traits: sociability and cautiousness. We found an effect of sex on sociability, where males were more sociable than females. In an additional analysis, we found that individuals who obtained food through contact provisioning had higher cautiousness scores than individuals who obtained food through non-contact provisioning. We discuss how the observed personality traits and their variations potentially offer adaptive advantages in human-dominated environments, where rhesus macaques face both benefits, such as anthropogenic subsidies and reduced predation, and costs, like exposure to anthropogenic stressors. We also emphasize that protocols designed for captive conditions may not be directly applicable to free-living animals. Thus, the study underscores the need to reconsider experimental designs to obtain comparable empirical evidence between captive and non-captive populations to enhance the ecological validity of personality assessments. Nevertheless, empirically identifying traits using observations in synanthropic species like rhesus macaques can still provide valuable insights into the mechanisms that enable certain animals to thrive amidst a rapid expansion of anthropogenic activities. Research highlightsStudying personalities of synanthropic animals can shed light on the biological traits that help them thrive in human-dominated environments. A bottom-up multi-method approach, standardized for assessing captive NHP personalities, was employed to study a population of synanthropic rhesus macaques. Behavioral observations captured two repeatable traits, namely sociability and cautiousness, where comparatively more cautious individuals obtained food through contact provisioning. Novelty experiments faced significant challenges.

animal behavior and cognition↗

bioRxiv2024

Personality homophily drives female friendships in a feral ungulate

Friendships, exhibited by both humans and non-human animals, have considerable adaptive benefits. In humans, similarity or homophily in personality is considered a proximate mechanism driving friendships, yet little is known about the behavioural decision rules underlying animal friendships. Some empirical research suggests that animal friendships can be driven by personality homophily. However, these studies are restricted to non-human primates, limiting our understanding of the mechanisms of friendships. We investigated a feral population of water buffalo (Bubalus bubalis) to determine whether homophily in personality drives friendships in this non-model social species in free-ranging environmental conditions. We conducted observations on females (n=30) and assessed their friendships and personalities. Close spatial proximity served as a behavioural indicator of friendship, validated by affiliative body contact. An objective bottom-up method revealed three personality traits - social tension, vigilance, and general dominance. We found that females with comparatively lower personality differences in social tension and general dominance traits exhibited significantly higher close spatial associations. We did not find an effect of kinship on close spatial associations. Our findings show that friendships in buffalo can form based on personality homophily, a decision rule attributed predominantly to primates. We discuss these findings in light of buffalo socioecology but emphasise their implications in the broader evolutionary context of animal personalities and friendships.

animal behavior and cognition↗

bioRxiv2023

Does novelty influence foraging decision of a scavenger?

Acquiring knowledge about the environment is crucial for survival. Animals, often driven by their explorative tendencies, gather valuable information regarding food resources, shelter, mating partners, etc. While neophilia, or the preference for novel environmental stimuli or objects, can promote exploratory behaviour, neophobia, or avoidance of novel environmental stimuli, can constrain such behaviour. Neophobia can reduce predation risk, yet decreased exploratory behaviour resulting from it may limit the ability to discover potentially highly rewarding resources. Dogs (Canis familiaris) living in semi-urban and urban environments as free-ranging populations are, although subject to various selection forces, typically have negligible predation pressure. These dogs are scavengers in human-dominated environments; thus, selection against object-neophobia can provide benefits when searching for novel food resources. Although pet and captive pack-living dogs are known to exhibit neophilia when provided with novel objects, little is known about free-ranging dogs behavioural responses to novel objects, particularly in foraging contexts. Using an object choice experiment, we tested 274 free-ranging dogs from two age classes, adult and juvenile, to investigate their object-neophobia in a scavenging context. We employed a betweensubject study design, providing dogs with a familiar and a potentially novel object, both baited with equal but (partially)hidden food rewards. Adult and juvenile dogs significantly inspected the novel object first compared to the familiar one, even when we reduced the visual obscurity of the familiar object, i.e., when the hidden food reward was partially visible. Furthermore, novel objects with varying strengths of olfactory cues (baited vs. false-baited) were inspected comparably by adults and juveniles. No significant differences were found in the latencies to inspect the objects. These results indicate that free-ranging dogs, evidently from an early ontogenic phase, do not show object-neophobia, as demonstrated by their preference for novel over familiar food sources. We conclude that little to no constraint of neophobia on exploratory behaviour, yet selection for object-neophilia in semi-urban and urban-dwelling animals can guide foraging decision-making processes, providing adaptive benefits.

animal behavior and cognition↗

bioRxiv2023

Personality heterophily and friendship as drivers for successful cooperation

Cooperation is widespread and arguably a pivotal evolutionary force in maintaining animal societies. Yet, proximately, what underlying motivators drive individuals to cooperate remains relatively unclear. Since free-riders can exploit the benefits by cheating, selecting the right partner is paramount. Such decision rules need not be based on complex calculations and can be driven by cognitively less-demanding mechanisms, like social relationships (e.g., kinship, non-kin friendships, dyadic tolerance), social status (e.g., dominance hierarchies) and personalities (social and non-social traits); however, holistic evidence related to those mechanisms is scarce. Using the classical loose-string paradigm, we tested cooperative tendencies of a hierarchical primate, the long-tailed macaque (Macaca fascicularis). We studied three groups (n=32) in social settings, allowing free partner choice. We supplemented cooperation with observational and experimental data on social relationships, dominance hierarchies, and personality. Friendship and dissimilarity in a non-social exploration personality trait predicted the likelihood of cooperative dyad formation. Furthermore, the magnitude of cooperative success was positively associated with friendship, low rank-distance, and dissimilarity in an activity-sociability personality trait. Kinship did not affect cooperation. While some findings align with prior studies, the evidence of (non-social)personality heterophily promoting cooperation may deepen our understanding of the proximate mechanisms and, broadly, the evolution of cooperation.

zoology↗

bioRxiv2023

Behavioural, physiological, and genetic drivers of coping

Animals regularly experience stressful situations, ranging from predation to social stress, yet successfully deal with them on most occasions. This adaptive mechanism, coping, reduces the adverse effects of stressors through behavioural and physiological efforts, failing to which may result in reduced fitness. However, considerable variation in coping is observed. Unlike in humans, coping is often considered a personality trait in non-human animals due to construct similarity, resulting in conceptual ambiguity. Besides, limited multidisciplinary research has rendered comprehending the drivers of coping in animals challenging. We assessed repetitive behavioural coping or coping styles (n=30), emotional arousal (n=12), and consistent inter-individual differences, i.e., personalities (n=32) of long-tailed macaques (Macaca fascicularis) using observations, ecologically relevant experiments, and infrared thermography. We finally investigated the association of coping with a Valine/Methionine polymorphism encoded by the Catechol-O-methyltransferase (COMT) gene (n=26), which is widely known for its involvement in human stress regulation. Our findings suggest that personality and the presence of the human equivalent COMT Val158Met polymorphism in long-tailed macaques are associated with emotion-focused and problem-focused coping styles. These coping styles were consistent with emotional arousal as measured with infrared thermography. We discuss these proximate drivers of coping for a better understanding of its evolution in primates.

animal behavior and cognition↗

bioRxiv2023

Butyrate enhances Clostridioides difficile sporulation in vitro

Short chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as the intestinal barrier, signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including importance in combatting infections caused by pathogens such as Clostridioides difficile. Despite the potential role of SCFAs in mitigating C. difficile infection, their direct effect on C. difficile remains unclear. Through a set of in vitro experiments, we investigated how SCFAs influence C. difficile growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of C. difficile strain 630 in a dose-dependent manner. The presence of butyrate also increased C. difficile sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with alternative metabolic and related C. difficile regulatory pathways, such as the carbon catabolite repressor, CcpA. Collectively, these data suggest that butyrate may signal alternative C. difficile metabolic pathways, thus modifying its growth and virulence to persist in the gut environment. IMPORTANCESeveral studies suggest that butyrate may be important in alleviating gut infections, such as reducing inflammation caused by the healthcare-associated Clostridioides difficile. While studies in both animal models and human studies correlate high levels of butyrate with reduced C. difficile burden, the direct impact of butyrate on C. difficile remains unclear. Our study demonstrates that butyrate directly influences C. difficile by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat C. difficile in a butyrate-directed manner.

microbiology↗

bioRxiv2023

Hand preference predicts behavioral responses to threats in Barbary macaques

The structure and functioning of the brain are lateralized - the right hemisphere processes unexpected stimuli and controls spontaneous behavior, while the left deals with familiar stimuli and routine responses. Hemispheric dominance, the predisposition of an individual using one hemisphere over the other, may lead to behavioral differences; particularly, an individual may be programmed to act in a certain way concerning hemispheric dominance. Hand preference is a robust estimator of hemispheric dominance in primates, as each brain hemisphere controls the opposing side of the body. Studies have found links between hand preference and the exhibition of different behaviors in contexts such as exploring and manipulating objects. However, little is known about whether hand preference can predict behavioral variations in other ecologically relevant contexts like, for example, predation. We investigated the relationship between hand preference and the behavioral responses to two types of predator models in captive Barbary macaques (Macaca sylvanus) (n=22). Hand preference was determined by observing unimanual foraging, whereas focus and tension behaviors were quantified during experimental exposure to predator models. We found 91% of the macaques to be lateralized with no group-level bias. In contrast to their right-hand counterparts, individuals with a strong left-hand preference elicited frequent focus and tension behavior. Additionally, the behavioral response varied with predator type. We also found an interaction effect between hand preference and the predator type. Our study suggests that hand preference can reliably predict behavioral variations in the context of potential predation. While these results are consistent with the lateralized brain function, indicating lateralization as a potential neural mechanism of behavioral variation, the interaction effect between hand preference and predator type elucidates the importance of context-specificity when investigating laterality non-invasively. Future research on other non-human primates using the current framework may shed light on the evolution of laterality and underlying behavioral predispositions.

animal behavior and cognition↗

bioRxiv2022

A drug's most potent target is not necessarily the source of its anti-cancer activity

The small-molecule drug ralimetinib was developed as an inhibitor of the kinase p38, and it has advanced to phase 2 clinical trials in oncology. Here, we apply a multi-modal approach to demonstrate that ralimetinibs anti-cancer activity occurs due to its ability to inhibit EGFR, rather than p38. We find that cancer cell lines driven by EGFR mutations exhibit the greatest sensitivity to ralimetinib treatment, and ralimetinib phenocopies established EGFR inhibitors in pharmacogenomic profiling experiments. We further demonstrate that ralimetinib inhibits EGFR kinase activity in vitro and in cellulo, albeit at >30-fold higher concentrations than it inhibits p38. Finally, while deletion of the gene encoding p38 has no effect on ralimetinib sensitivity, expression of the EGFR-T790M gatekeeper mutation confers resistance to ralimetinib treatment. These findings suggest that future clinical trials involving ralimetinib could incorporate EGFR mutation status as a biomarker to identify sensitive patients. Moreover, our results demonstrate that a compounds anti-cancer effects should not necessarily be attributed to the protein that it inhibits most strongly, and instead, comprehensive cellular and genetic profiling is required to understand a drugs mechanism-of-action.

cancer biology↗

bioRxiv2022

Prosociality in a despotic society

Humans possess remarkable prosocial tendencies beyond the confinement of kinship, which may be instrumental in promoting cooperative interactions and sociality at large. Yet, prosociality is an evolutionary conundrum as it does not provide immediate benefits to the actor. The domestication and cooperative-breeding hypotheses postulated that enhanced social tolerance and inter-individual dependence could nonetheless facilitate the evolution of prosociality. However, inconsistent results due to varying experimental paradigms, and restricted focus of research on tolerant and cooperatively breeding species, have impeded our understanding so far. Albeit counterintuitively, despotic societies with relatively low social tolerance levels represent an excellent opportunity to investigate prosociality due to their kin favoritism and potential interdependence among individuals in terms of social support. Japanese macaques (Macaca fuscata) live in strictly hierarchical matrilineal societies, where kin members have strong social bonds. Additionally, support from non-kins can be crucial to form coalitions and rank up in the hierarchy. Using a group-service paradigm, we tested prosociality in a semi-free-ranging group of Japanese macaques. In contrast to currently existing evidence, we found that individuals (n=25) can act prosocially and at comparably high rates as cooperative breeding- or self-domesticated species. The macaques benefitted not only their kin members but other individuals to whom they showed relatively high social tolerance. We emphasize the roles of complex socio-ecological conditions in facilitating individual prosocial tendencies. Furthermore, these results call for a novel evolutionary framework regarding prosociality that focuses on different forms of interdependence and expands beyond cooperative breeding- and (self-)domesticated species. Significance statementWhat made humans so incredibly prosocial? Examining the evolutionary trajectory of prosocial acts led comparative psychologists to explore various taxa. Empirical evidence so far suggests that enhanced social tolerance and interdependence among individuals facilitate prosociality. Conventionally, despotism is characterized by low group-level tolerance, yet kin favoritism, nepotism, and high interdependence (in support and coalition formation) are also fundamental properties of despotic societies. Under such complex socio-ecological conditions, individual prosocial acts could thus be vital. We found, for the first time, high levels of prosociality in the very despotic Japanese macaques. Individuals benefitted both kin-relatives and others to whom they showed relatively high dyadic social tolerance. This study signifies that prosociality can be favored even in a highly despotic society.

animal behavior and cognition↗

bioRxiv2022

Diversity and prevalence of Clostridium innocuum in the human gut microbiota

Clostridia are a polyphyletic group of Gram-positive, spore-forming anaerobes in the Firmicutes phylum that significantly impact metabolism and functioning of human gastrointestinal tract. Recently, Clostridia were divided into two separate classes, Clostridia and Erysipelotrichia, based on phenotypic and 16S rRNA gene-based differences. While Clostridia include many well-known pathogenic bacteria, Erysipelotrichia remain relatively uncharacterized, particularly regarding their role as a pathogen vs. commensal. Despite wide recognition as a commensal, the Erysipelotrichial species, Clostridium innocuum, has recently been associated with various disease states. To further understand the ecological and potential virulent role of C. innocuum, we conducted a genomic comparison across 38 C. innocuum isolates and 75 publicly available genomes. Based on colony morphology, we isolated multiple C. innocuum cultivars from the feces of healthy human volunteers (n=5). Comparison of the 16S rRNA gene of our isolates against publicly available microbiota datasets in healthy individuals suggests a high prevalence of C. innocuum across the human population (> 80%). Analysis of single nucleotide polymorphisms (SNPs) across core genes and average nucleotide identify (ANI) revealed the presence of 4 clades among all available unique genomes (n=108 total). Investigation of carbohydrate and protein utilization pathways, including comparison against the carbohydrate-activating-enzyme (CAZyme) database, demonstrated inter-and intra-clade differences that were further substantiated in vitro. Collectively, these data indicate genetic variance within the C. innocuum species that may help clarify its role in human disease and health. IMPORTANCEClostridia are a group of medically important anaerobes as both commensals and pathogens. Recently, a new class of Erysipelotrichia containing a number of re-assigned Clostridial species has emerged, including Clostridium innocuum. Recent studies have implicated C. innocuum as a potential causative agent of diarrhea in patients from whom Clostridioides difficile could not be isolated. Using genomic and in vitro comparison, this study sought to characterize C. innocuum in the healthy human gut. Our analyses suggest that C. innocuum is a highly prevalent and diverse species, demonstrating clade-specific differences in metabolism and potential virulence. Collectively, this study is the first investigation into a broader description of C. innocuum as a human gut inhabitant.

microbiology↗