Terrestrial Mammals Research Articles

Current national nature reserves are insufficient to safeguard the long-term survival of birds and mammals in China

Enhancing the connectivity of protected areas is a global consensus for conserving biodiversity. Yet, it is unclear whether habitats are sufficiently connected within protected areas to efficiently protect wildlife populations for long-term survival. Here we show that, in general, China’s national nature reserves can effectively protect about one-half of the bird and mammal populations within protected areas for long-term survival. However, they can only protect 25% of birds and 13% of terrestrial mammals with high motility. Areas of low conservation effectiveness are highly overlapped with protected areas of small size and high intensity of human activity. Artificial landscapes (arable land and built-up land), which account for less than 2% area of the protected areas, disproportionately cause nearly 40% of the connectivity loss. The results suggest that maintaining high levels of functional connectivity within protected areas is as important as maintaining high connectivity in the national or global protected area networks. Our findings have important implications for improving the management of protected areas in China and beyond.

USE OF VISCOELASTIC COAGULATION TESTING IN MEGACHIROPTERA (PTEROPUS HYPOMELANUS AND PTEROPUS VAMPYRUS) REVEALS HIGH VARIABILITY IN CLOT KINETICS.

Megachiroptera is a mammalian suborder that includes old world fruit bats. Common clinical problems among captive Megachiroptera, such as liver disease (e.g., iron storage disease), kidney disease (e.g., protein-losing nephropathy), and heart disease (e.g., dilated cardiomyopathy), carry elevated risk for hemostatic derangements. The assessment of viscoelastic coagulation assays, however, has not yet been reported in bats. The main objective of the study was to describe viscoelastography data using the Viscoelastic Coagulation Monitor (VCM) Vet in captive large flying foxes (Pteropus vampyrus) (n = 20) and variable flying foxes (Pteropus hypomelanus) (n = 10). Additional objectives were to compare viscoelastic and clotting parameters (1) between healthy P. vampyrus and P. hypomelanus bats and (2) between untreated bats and those treated with meloxicam or aspirin, and (3) to examine relationships between activated partial thromboplastin time (aPTT) and potentially homologous viscoelastic parameters clotting time (CT) and clot formation time (CFT). The results showed marked variability among clinically normal bats. The intrinsic pathway, as measured by aPTT, had prolonged times compared with most terrestrial mammals, but similar times to birds, marine mammals, and sea turtles. A search of P. vampyrus genome found stop codons present in two exons of the factor XI gene; alterations in factor XI expression would be expected to alter intrinsic coagulation. Because of the high variability, no statistically significant findings were noted in the secondary objectives. Correlation between aPTT and CT or CFT was not strong (rs = 0.406 or 0.192, respectively). The results from this study suggest that clot kinetics vary widely among Megachiroptera when using the VCM Vet with untreated blood. A prolonged intrinsic coagulation pathway, as has been found in other megachiropteran species, and activation of the extrinsic coagulation pathway during venipuncture may be responsible for the inconsistent results.

Inter-annual variation in the microplastics abundance in feces of the Baird's tapir (Tapirus bairdii) from the Selva Maya, México

Microplastics (MPs) are found in a wide range of ecosystems, from the Arctic to the deep ocean. However, there is no data on their presence in terrestrial mammals that inhabit the Selva Maya. The aim of this study is to detect the presence of MPs in the feces of the Baird's tapir (Tapirus bairdii) from the region of Calakmul, located in the Yucatan Peninsula, Mexico. We analyzed 129 fecal samples collected during 2017 and 2018, obtaining 57 and 72 samples during the rainy and dry seasons respectively. Sixty-eight percent of the samples contained 743 MPs with a mean of 19.3 ± 28.1 MPs/kg of dry weight (DW) feces in both years. An inter-annual variation in the average abundance of microplastic was observed during the two-year period (2017–2018), with a 72 % increase in these plastic particles in feces. Fourteen polymers were identified, with ethylene vinyl acetate (EVA), polypropylene (PP) and polyester (PES) being the most abundant during both years. Although the effects of MPs on the health of tapirs are not known, their presence is cause for concern. There is an urgent need for the implementation of appropriate plastic waste management programs in communities of the Selva Maya to diminish the consumption of MPs in species including humans where they pose a significant risk to health. Environmental implicationsThe use of plastics worldwide is increasing every day, so the presence of microplastics is and will continue to be a major environmental problem. It is known that contaminants can adhere to plastics, making them hazardous materials. Microplastics can contaminate remote areas such as Biosphere Reserves. Terrestrial species such as the tapir can ingest microplastics, putting their health at risk. Knowing the dispersion of microplastics is very important in order to manage them properly, taking into account their emission sources and type of polymer.

Current understanding and knowledge gaps regarding wildlife as reservoirs of antimicrobial resistance.

Antimicrobial resistance (AMR) is a serious health issue shared across all One Health domains. Wildlife species represent a key intersection of the animal and environmental domains. They are a relevant but understudied reservoir and route of spread for AMR throughout the environment. Most wildlife AMR research thus far has focused on avian species, terrestrial mammals, and a selection of aquatic and marine species. Pathogens often identified in terrestrial wildlife include enteric zoonotic organisms such as Eschericia coli and Salmonella spp, in addition to nonenterics such as Staphylococci. Resistances have been commonly identified to antimicrobials important in veterinary and human medicine, including β-lactams, tetracyclines, aminoglycosides, and macrolides. Our emerging understanding of the dynamics of AMR distribution across life on Earth provides further opportunities for us to assess the risk it poses to veterinary and human health. Future work will require prioritizing which wildlife most exacerbates and indicates AMR in domestic animals. However, decreasing prices and increasing ease for metagenomic sequencing allows for synergies with expanding wildlife viral disease surveillance. Improved understanding of how wildlife impacts veterinary and human healthcare may increase opportunities for related research funding and global equity in such research. The companion Currents in One Health article by Vezeau and Kahn, JAVMA, June 2024, addresses in further detail the routes of spread of AMR across different animal populations and actions that can be taken to mitigate AMR with special consideration for wildlife sources.

No evidence for the consistent effect of supplementary feeding on home range size in terrestrial mammals.

Food availability and distribution are key drivers of animal space use. Supplemental food provided by humans can be more abundant and predictable than natural resources. It is thus believed that supplementary feeding modifies the spatial behaviour of wildlife. Yet, such effects have not been tested quantitatively across species. Here, we analysed changes in home range size owing to supplementary feeding in 23 species of terrestrial mammals using a meta-analysis of 28 studies. Additionally, we investigated the moderating effect of factors related to (i) species biology (sex, body mass and taxonomic group), (ii) feeding regimen (duration, amount and purpose), and (iii) methods of data collection and analysis (source of data, estimator and spatial confinement). We found no consistent effect of supplementary feeding on changes in home range size. While an overall tendency of reduced home range was observed, moderators varied in the direction and strength of the trends. Our results suggest that multiple drivers and complex mechanisms of home range behaviour can make it insensitive to manipulation with supplementary feeding. The small number of available studies stands in contrast with the ubiquity and magnitude of supplementary feeding worldwide, highlighting a knowledge gap in our understanding of the effects of supplementary feeding on ranging behaviour.

Single cell RNA analysis uncovers the cell differentiation and functionalization for air breathing of frog lung

The evolution and development of vertebrate lungs have been widely studied due to their significance in terrestrial adaptation. Amphibians possess the most primitive lungs among tetrapods, underscoring their evolutionary importance in bridging the transition from aquatic to terrestrial life. However, the intricate process of cell differentiation during amphibian lung development remains poorly understood. Using single-cell RNA sequencing, we identify 13 cell types in the developing lungs of a land-dwelling frog (Microhyla fissipes). We elucidate the differentiation trajectories and mechanisms of mesenchymal cells, identifying five cell fates and their respective driver genes. Using temporal dynamics analyses, we reveal the gene expression switches of epithelial cells, which facilitate air breathing during metamorphosis. Furthermore, by integrating the published data from another amphibian and two terrestrial mammals, we illuminate both conserved and divergent cellular repertoires during the evolution of tetrapod lungs. These findings uncover the frog lung cell differentiation trajectories and functionalization for breathing in air and provide valuable insights into the cell-type evolution of vertebrate lungs.

Stable isotope evidence for resource partitioning in extinct marine carnivores

Living pinnipeds play essential roles in marine ecosystems and display divergent lineage-specific foraging and habitat preferences. The origin of these ecological strategies remains unclear. We analyzed original (n = 22) and published (n = 93) stable carbon (δ13C) and oxygen (δ18O) isotope compositions of tooth enamel from fossil pinnipeds and coeval marine and terrestrial mammals from the late Early Miocene to early Middle Miocene Temblor Formation, the early Middle Miocene Round Mountain Silt Formation at Sharktooth Hill Bonebed, the Middle Miocene of lower levels of the Monterey Formation, and the late Middle Miocene Santa Margarita Formation from the eastern North Pacific Ocean; and original (n = 43) δ13C and δ18O values from the Early Pliocene Yorktown Formation in the western North Atlantic. As expected for aquatic mammals, pinnipeds and control marine mammals had low δ18O variability relative to coeval terrestrial mammals, indicating minimal diagenetic alteration. Among late Early Miocene and Middle Miocene pinnipeds, Allodesmus had lower δ13C values than coeval taxa indicating offshore foraging, in agreement with predictions based on skeletal morphology. However, Allodesmus from the late Middle Miocene Santa Margarita Formation had overlapping δ13C values with co-occurring cetaceans and pinnipeds suggesting preferential nearshore habitat. The stem otariid Pithanotaria had higher enamel δ13C values than co-occurring pinnipeds, indicating nearshore foraging. The stem odobenid Neotherium had intermediate δ13C values supporting foraging between nearshore and offshore predators. Conversely, the stem odobenid cf. Imagotaria had lower enamel δ18O but comparable δ13C values to coexisting pinnipeds, suggesting the exploitation of estuarine resources. At least two ecologically distinct pinniped groups also occurred in the Yorktown Formation. In this unit, the odobenid Ontocetus and some monachinae phocids were predominantly nearshore foragers, with higher enamel δ13C and δ18O values than simultaneously occurring marine mammals. The second group was exclusively composed of phocids, which had comparatively low δ13C and δ18O values, compatible with northward foraging movements along the western North Atlantic coast. The paleoecological profiles of fossils bear strong similarities to the life modes of extant pinniped communities, implying that extant foraging modes appeared early in pinniped evolution and that resource partitioning contributed to their community structure over time.

The vomeronasal organ and incisive duct of harbor seals are modified to secrete acidic mucus into the nasal cavity

Most terrestrial mammals have a vomeronasal system to detect specific chemicals. The peripheral organ of this system is a vomeronasal organ (VNO) opening to the incisive duct, and its primary integrative center is an accessory olfactory bulb (AOB). The VNO in seals is thought to be degenerated like whales and manatees, unlike otariids, because of the absence of the AOB. However, olfaction plays pivotal roles in seals, and thus we conducted a detailed morphological evaluation of the vomeronasal system of three harbor seals (Phoca vitulina). The VNO lumen was not found, and the incisive duct did not open into the oral cavity but was recognized as a fossa on the anteroventral side of the nasal cavity. This fossa is rich in mucous glands that secrete acidic mucopolysaccharides, which might originate from the vomeronasal glands. The olfactory bulb consisted only of a main olfactory bulb that received projections from the olfactory mucosa, but an AOB region was not evident. These findings clarified that harbor seals do not have a VNO to detect some chemicals, but the corresponding region is a specialized secretory organ.

No evidence for a signal in mammalian basal metabolic rate associated with a fossorial lifestyle.

A vast array of challenging environments are inhabited by mammals, such as living in confined spaces where oxygen levels are likely to be low. Species can exhibit adaptations in basal metabolic rate (BMR) to exploit such unique niches. In this study we use 801 species to determine the relationship between BMR and burrow use in mammals. We included pre-existing data for mammalian BMR and 16 life history traits. Overall, mammalian BMR is dictated primarily by environmental ambient temperature. There were no significant differences in BMR of terrestrial, semi-fossorial and fossorial mammals, suggesting that species occupying a subterranean niche do not exhibit baseline metabolic costs on account of their burrowing lifestyle. Fossorial mammals likely show instantaneous metabolic responses to low oxygen in tunnels, rather than exhibit adaptive long-term responses in their BMR.

Editorial: Advances in the conservation of large terrestrial mammals

Editorial: Advances in the conservation of large terrestrial mammals

Extralimital terrestrials: A reassessment of range limits in Alaska's land mammals.

Understanding and mitigating the effects of anthropogenic climate change on species distributions requires the ability to track range shifts over time. This is particularly true for species occupying high-latitude regions, which are experiencing more extreme climate change than the rest of the world. In North America, the geographic ranges of many mammals reach their northernmost extent in Alaska, positioning this region at the leading edge of climate-induced distribution change. Over a decade has elapsed since the publication of the last spatial assessments of terrestrial mammals in the state. We compared public occurrence records against commonly referenced range maps to evaluate potential extralimital records and develop repeatable baseline range maps. We compared occurrence records from the Global Biodiversity Information Facility for 61 terrestrial mammal species native to mainland Alaska against a variety of range estimates (International Union for Conservation of Nature, Alaska Gap Analysis Project, and the published literature). We mapped extralimital records and calculated proportions of occurrences encompassed by range extents, measured mean direction and distance to prior range margins, evaluated predictive accuracy of published species models, and highlighted observations on federal lands in Alaska. Range comparisons identified 6,848 extralimital records for 39 of 61 (63.9%) terrestrial mainland Alaskan species. On average, 95.5% of Alaska Gap Analysis Project occurrence records and ranges were deemed accurate (i.e., > 90.0% correct) for 31 of 37 species, but overestimated extents for 13 species. The International Union for Conservation of Nature range maps encompassed 68.1% of occurrence records and were > 90% accurate for 17 of 39 species. Extralimital records represent either improved sampling and digitization or actual geographic range expansions. Here we provide new data-driven range maps, update standards for the archiving of museum-quality locational records and offer recommendations for mapping range changes for monitoring and conservation.

The ecological and biodiversity conservation values of farm dams: A systematic review.

Biodiversity is in rapid decline globally with agriculture being one of the leading causes. Within agricultural landscapes, some features provide a benefit to biodiversity that is disproportionate to their spatial area. An interesting example is artificial ponds-or farm dams-which can support a large variety of taxa. Here, we present a global review of farm dam research related to biodiversity conservation objectives to provide an overview of the topics, key research insights, and the characteristics of current research. We used a three-stage process to screen literature and identified 104 relevant papers across 27 countries encompassing studies of 13 different taxa. Most of the studies were short-term (less than 5 years) with small sample sizes (less than 20 sites). Of the 104 papers, 88 were focussed primarily on ecological outcomes, such as species richness or abundance, and 15 on primary production outcomes, such as crop and livestock yield, despite addressing or measuring ecological metrics. Only one study measured both ecological and primary production outcomes. Studies frequently examined how the features of dams (79 studies) and attributes of the surrounding landscape (47 studies) impact particular species and communities. Terrestrial mammals (1 study) were under-represented in the literature with macrophytes (28 studies), macroinvertebrates (26 studies), and amphibians (19 studies) receiving the most attention. Our results reveal a growing trend towards recognizing farm dams as habitats for various taxa, including amphibians, beetles, dragonflies, and other macroinvertebrates within agricultural environments. Significant knowledge gaps exist in understanding how dam age, invasive species, and effective management practices impact the biodiversity conservation values of farm dams. Future research should emphasize enhancing biodiversity by collaborating with landholders to increase habitat through strategic vegetation planning, minimizing runoff and nutrient inflow, and restricting stock access.

Breathing Air and Living Underwater: Molecular Evolution of Genes Related to Antioxidant Response in Cetaceans and Pinnipeds.

Cetaceans and pinnipeds are lineages of mammals that have independently returned to the aquatic environment, acquiring varying degrees of dependence on it while sharing adaptations for underwater living. Here, we focused on one critical adaptation from both groups, their ability to withstand the ischemia and reperfusion experienced during apnea diving, which can lead to the production of reactive oxygen species (ROS) and subsequent oxidative damage. Previous studies have shown that cetaceans and pinnipeds possess efficient antioxidant enzymes that protect against ROS. In this study, we investigated the molecular evolution of key antioxidant enzyme genes (CAT, GPX3, GSR, PRDX1, PRDX3, and SOD1) and the ROS-producing gene XDH, in cetaceans and pinnipeds lineages. We used the ratio of non-synonymous (dN) to synonymous (dS) substitutions as a measure to identify signatures of adaptive molecular evolution in these genes within and between the two lineages. Additionally, we performed protein modeling and variant impact analyzes to assess the functional consequences of observed mutations. Our findings revealed distinct selective regimes between aquatic and terrestrial mammals in five of the examined genes, including divergences within cetacean and pinniped lineages, between ancestral and recent lineages and between crowns groups. We identified specific sites under positive selection unique to Cetacea and Pinnipedia, with one site showing evidence of convergent evolution in species known for their long and deep-diving capacities. Notably, many sites under adaptive selection exhibited radical changes in amino acid properties, with some being damaging mutations in human variations, but with no apparent detrimental impacts on aquatic mammals. In conclusion, our study provides insights into the adaptive changes that have occurred in the antioxidant systems of aquatic mammals throughout their evolutionary history. We observed both distinctive features within each group of Cetacea and Pinnipedia and instances of convergence. These findings highlight the dynamic nature of the antioxidant system in response to challenges of the aquatic environment and provide a foundation for further investigations into the molecular mechanisms underlying these adaptations.

Polystyrene nanoplastics mediate oxidative stress, senescence, and apoptosis in a human alveolar epithelial cell line.

Nanoplastics, an emerging form of pollution, are easily consumed by organisms and pose a significant threat to biological functions due to their size, expansive surface area, and potent ability to penetrate biological systems. Recent findings indicate an increasing presence of airborne nanoplastics in atmospheric samples, such as polystyrene (PS), raising concerns about potential risks to the human respiratory system. This study investigates the impact of 800 nm diameter-PS nanoparticles (PS-NPs) on A549, a human lung adenocarcinoma cell line, examining cell viability, redox balance, senescence, apoptosis, and internalization. We also analyzed the expression of hallmark genes of these processes. We demonstrated that PS-NPs of 800 nm in diameter significantly affected cell viability, inducing oxidative stress, cellular senescence, and apoptosis. PS-NPs also penetrated the cytoplasm of A549 cells. These nanoparticles triggered the transcription of genes comprised in the antioxidant network [SOD1 (protein name: superoxide dismutase 1, soluble), SOD2 (protein name: superoxide dismutase 2, mitochondrial), CAT (protein name: catalase), Gpx1 (protein name: glutathione peroxidase 1), and HMOX1 (protein name: heme oxygenase 1)], senescence-associated secretory phenotype [Cdkn1a (protein name: cyclin-dependent kinase inhibitor 1A), IL1A (protein name: interleukin 1 alpha), IL1B (protein name: interleukin 1 beta), IL6 (protein name: interleukin 6), and CXCL8 (protein name: C-X-C motif chemokine ligand 8)], and others involved in the apoptosis modulation [BAX (protein name: Bcl2 associated X, apoptosis regulator), CASP3 (protein name: caspase 3), and BCL2 (protein name: Bcl2, apoptosis regulator)]. Collectively, this investigation underscores the importance of concentration (dose-dependent effect) and exposure duration as pivotal factors in assessing the toxic effects of PS-NPs on alveolar epithelial cells. Greater attention needs to be directed toward comprehending the risks of cancer development associated with air pollution and the ensuing environmental toxicological impacts on humans and other terrestrial mammals.

On the Dynamics of Mortality and the Ephemeral Nature of Mammalian Megafauna.

AbstractEnergy flow through consumer-resource interactions is largely determined by body size. Allometric relationships govern the dynamics of populations by impacting rates of reproduction as well as alternative sources of mortality, which have differential impacts on smaller to larger organisms. Here we derive and investigate the timescales associated with four alternative sources of mortality for terrestrial mammals: mortality from starvation, mortality associated with aging, mortality from consumption by predators, and mortality introduced by anthropogenic subsidized harvest. The incorporation of these allometric relationships into a minimal consumer-resource model illuminates central constraints that may contribute to the structure of mammalian communities. Our framework reveals that while starvation largely impacts smaller-bodied species, the allometry of senescence is expected to be more difficult to observe. In contrast, external predation and subsidized harvest have greater impacts on the populations of larger-bodied species. Moreover, the inclusion of predation mortality reveals mass thresholds for mammalian herbivores, where dynamic instabilities may limit the feasibility of megafaunal populations. We show how these thresholds vary with alternative predator-prey mass relationships, which are not well understood within terrestrial systems. Finally, we use our framework to predict the harvest pressure required to induce mass-specific extinctions, which closely align with previous estimates of anthropogenic megafaunal exploitation in both paleontological and historical contexts. Together our results underscore the tenuous nature of megafaunal populations and how different sources of mortality may contribute to their ephemeral nature over evolutionary time.

Dietary glycine supplementation enhances syntheses of creatine and glutathione by tissues of hybrid striped bass (Morone saxatilis ♀ × Morone chrysops ♂) fed soybean meal-based diets

BackgroundWe recently reported that supplementing glycine to soybean meal-based diets is necessary for the optimum growth of 5- to 40-g (Phase-I) and 110- to 240-g (Phase-II) hybrid striped bass (HSB), as well as their intestinal health. Although glycine serves as an essential substrate for syntheses of creatine and glutathione (GSH) in mammals (e.g., pigs), little is known about these metabolic pathways or their nutritional regulation in fish. This study tested the hypothesis that glycine supplementation enhances the activities of creatine- and GSH-forming enzymes as well as creatine and GSH availabilities in tissues of hybrid striped bass (HSB; Morone saxatilis♀ × Morone chrysops♂).MethodsPhase-I and Phase-II HSB were fed a soybean meal-based diet supplemented with 0%, 1%, or 2% glycine for 8 weeks. At the end of the 56-d feeding, tissues (liver, intestine, skeletal muscle, kidneys, and pancreas) were collected for biochemical analyses.ResultsIn contrast to terrestrial mammals and birds, creatine synthesis occurred primarily in skeletal muscle from all HSB. The liver was most active in GSH synthesis among the HSB tissues studied. In Phase-I HSB, supplementation with 1% or 2% glycine increased (P < 0.05) concentrations of intramuscular creatine (15%–19%) and hepatic GSH (8%–11%), while reducing (P < 0.05) hepatic GSH sulfide (GSSG)/GSH ratios by 14%–15%, compared with the 0-glycine group; there were no differences (P > 0.05) in these variables between the 1% and 2% glycine groups. In Phase-II HSB, supplementation with 1% and 2% glycine increased (P < 0.05) concentrations of creatine and GSH in the muscle (15%–27%) and liver (11%–20%) in a dose-dependent manner, with reduced ratios of hepatic GSSG/GSH in the 1% or 2% glycine group. In all HSB, supplementation with 1% and 2% glycine dose-dependently increased (P < 0.05) activities of intramuscular arginine:glycine amidinotransferase (22%–41%) and hepatic γ-glutamylcysteine synthetase (17%–37%), with elevated activities of intramuscular guanidinoacetate methyltransferase and hepatic GSH synthetase and GSH reductase in the 1% or 2% glycine group. Glycine supplementation also increased (P < 0.05) concentrations of creatine and activities of its synthetic enzymes in tail kidneys and pancreas, and concentrations of GSH and activities of its synthetic enzymes in the proximal intestine.ConclusionsSkeletal muscle and liver are the major organs for creatine and GSH syntheses in HSB, respectively. Dietary glycine intake regulates creatine and GSH syntheses by both Phase-I and Phase-II HSB in a tissue-specific manner. Based on the metabolic data, glycine is a conditionally essential amino acid for the growing fish.

Site occupancy of native terrestrial mammals in oil palm landscapes is driven by the synergy of land sparing and sharing strategies

The conversion of tropical rainforests into industrial oil palm monocultures has detrimental effects of local biodiversity. Although some medium-sized mammals have demonstrated a degree of adaptability in oil palm landscapes, the factors that influence their ability to persist in such human-altered environments remain obscure. Here, we investigated the site occupancy and activity pattern of the mammals in oil palm landscapes in Peninsular Malaysia. We deployed 81 camera traps throughout six oil palm cultivation areas with two distinct management styles (three sites each in organized smallholdings and industrial plantations). Smallholdings had higher site occupancy of native animal species than industrial plantations. The site occupancy of the mammals was influenced by the proximity to continuous forest, forest patches and riparian vegetation. Landscape metrics are characteristics that affect land sparing strategy, allowing wildanimals in agricultural landscapes to thrive in their habitat despite human threats. At stand-level, the detection of animals was determined by elevation, undergrowth vegetation cover/height, canopy cover, oil palm height, quantity of oil palm fruits, and prune stack thickness. Mammal occupancy was higher in the smallholdings due to the proximity to continuous forest. We recommend improving landscape heterogeneity and connectivity in oil palm matrix to promote species mobility and diversifying oil palm management away from monoculture farming. Our findings indicate that incorporating land sharing and sparing strategies into the oil palm matrix is necessary to conserve biodiversity and maintain ecological services. This implies that industry stakeholders ought not to disregard either land sparing or land sharing.

The role of gut microbiota in mediating increased toxicity of nano-sized polystyrene compared to micro-sized polystyrene in mice

Microplastics (MPs) are widespread environmental contaminants that have been detected in animals and humans. However, their toxic effects on terrestrial mammals and the underlying mechanisms are still not well understood. Herein, we explored the role of gut microbiota in mediating the toxicity of micro- and nano-sized polystyrene plastics (PS-MPs/PS-NPs) using an antibiotic depleted mice model. The results showed that PS-MPs and PS-NPs exposure disrupted the composition and structure of the gut microbiota. Specifically, these particles led to an increase in pathogenic Esherichia-shigella, while depleting probiotics such as Akkermansia and Lactobacillus. Comparatively, PS-NPs particles had more pronounced effect, leading to obviously shifted the colon transcriptional profiles characterized by inducing the enrichment of colon metabolism and immune-related pathways (i.e., upregulated in genes like udgh, ugt1a1, ugt1a6a, ugt1a7c and ugt2b34). Additionally, both PS-MPs and PS-NPs induced oxidative stress, gut-liver damage and systemic inflammation in mice. Mechanistically, we confirmed that PS particles disturbed gut microbiota, activating TLR2-My88-NF-κB pathway to trigger the release of inflammatory cytokine IL-1β and TNF-α. The damage and inflammation caused by both size of PS particles was alleviated when the gut microbiota was depleted. In conclusion, our findings deepen the understanding of the molecule mechanisms by which gut microbiota mediate the toxicity of PS particles, informing health implications of MPs pollution.

Serum Proteins Infer Molecular Protection Against Inflammation in Weddell Seal (Leptonychotes weddellii) Blood

Weddell seals ( Leptonychotes weddellii) are elite divers able to dive up to 900 meters deep and remain submerged for over 90 minutes. Weddell seals have a dramatic dive response to allow for longer, deeper dives including intense bradycardia and constriction of blood vessels, especially those supplying peripheral or visceral organs. Vasoconstriction, hypo-perfusion and subsequent re-oxygenation upon surfacing is known to induce tissue injury in terrestrial mammals via inflammation. Previous work interrogating the Weddell seal’s innate immune system suggested a component in the seal’s blood serum that protects against inflammation. We are using a mouse macrophage (RAW 264.7) cell model to characterize components of the seal’s blood that are anti-inflammatory to lipopolysaccharide (LPS). When exposed to 10 ng/mL LPS, RAW cells supplemented with deproteinated serum from adult Weddell seals lose their protection against inflammation, having 11-fold greater induction of interleukin-6 (IL-6) mRNA expression after a 6-h exposure compared to RAW cells supplemented with intact seal serum (T=3.29, p=0.01). To determine whether anti-inflammatory capacity of serum is innately present in Weddell seals or whether it is acquired in conjunction with development of diving capacity, we compared the protective effects of adult Weddell seal serum against serum from Weddell seal pups collected at approximately their age of weaning, when they had begun diving activities but do not yet dive deep. Following exposure to 10 ng/mL LPS, IL-6 expression was 69% lower in RAW cells supplemented with serum from adult seals compared to those supplemented with serum from pups (T=8.41, p=0.002), suggesting that ontogeny or diving behavior contributes to the development of anti-inflammatory serum. Analysis of adult (n=12) and pup (n=11) serum proteomes revealed a single protein, colony stimulating factor 2 receptor subunit beta (CSF2RB), with a 24-fold higher abundance in adults (PFDR&lt;0.0001). CSF2RB is a pleiotropic cell surface receptor subunit with known functions in innate immunity, erythropoiesis, as well as tissue protection. Therefore, we hypothesize that it plays a role in the anti-inflammatory protection observed in adult seals. Defining the mechanism of action for this protein in seal serum could identify a protective adaptation that facilitates deep and long dives. In a broader context, lessons learned from an extreme diving mammals may identify anti-inflammatory strategies with new clinical relevance. NSF #1921491; #1853326; #2337400. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparative genomics of sirenians reveals evolution of filaggrin and caspase-14 upon adaptation of the epidermis to aquatic life

The mammalian epidermis has evolved to protect the body in a dry environment. Genes of the epidermal differentiation complex (EDC), such as FLG (filaggrin), are implicated in the barrier function of the epidermis. Here, we investigated the molecular evolution of the EDC in sirenians (manatees and dugong), which have adapted to fully aquatic life, in comparison to the EDC of terrestrial mammals and aquatic mammals of the clade Cetacea (whales and dolphins). We show that the main subtypes of EDC genes are conserved or even duplicated, like late cornified envelope (LCE) genes of the dugong, whereas specific EDC genes have undergone inactivating mutations in sirenians. FLG contains premature stop codons in the dugong, and the ortholog of human CASP14 (caspase-14), which proteolytically processes filaggrin, is pseudogenized in the same species. As FLG and CASP14 have also been lost in whales, these mutations represent convergent evolution of skin barrier genes in different lineages of aquatic mammals. In contrast to the dugong, the manatee has retained functional FLG and CASP14 genes. FLG2 (filaggrin 2) is truncated in both species of sirenians investigated. We conclude that the land-to-water transition of sirenians was associated with modifications of the epidermal barrier at the molecular level.