Interspecies Interactions Research Articles

Fecal DNA metabarcoding reveals the winter diet of Eurasian otter (Lutra lutra) in Northeast China

As the top predator of freshwater ecosystems, the Eurasian otter (Lutra lutra) plays a vital role in maintaining food web structure and ecosystem stability. Understanding the dietary composition and dynamics of the Eurasian otter is crucial for comprehending its ecosystem function and interspecies interactions, providing vital information for determining conservation and management strategies. Currently, DNA metabarcoding technology has been extensively applied in dietary studies as a more effective and accurate method for identifying prey species. However, there remains an insufficient amount of research on otter diet using this technology, especially in Northeast China. In this study, we analyzed the vertebrate dietary composition and spatial variation of otters during the winter in Northeast China using DNA metabarcoding technology. We confirm 106 fecal samples belonging to Eurasian otter DNA from 118 putative otters fecal samples, and then performed polymerase chain reaction (PCR) amplifications using vertebrate universal primers with the otter blocking primer (OBS1) and the human blocking primer (HomoB) to the sequence. Subsequently, high-throughput sequencing was performed to analyze the dietary composition of Eurasian otter. We identified a total of 34 prey taxa, including 31 fish, 2 frog and 1bird. Our results showed that the winter diet of the Eurasian otter was dominated by fish (60.11 %), (e.g., Cottidae, Cyprinidae), followed by Ranidae (39.88 %). Furthermore, geographical variations in dietary preferences were observed. This study confirms that Eurasian otter is a generalist piscivorous predator, and that its diet could be related to the availability of resources in the habitat. This study enriches the information on the diet of Eurasian otter, and can be used to provide a reference for the development of effective conservation strategies. At the same time, it confirms the reliability of the fecal DNA metabarcoding technique for carnivore predation analysis, and provides a new perspective for the investigation and research of otters and other mammals.

Optimizing anaerobic digestion: Benefits of mild temperature transition from thermophilic to mesophilic conditions

Anaerobic digestion (AD) plays a significant role in renewable energy recovery. Upgrading AD from thermophilic (50–57 °C) to mesophilic (30–38 °C) conditions to enhance process stability and reduce energy input remains challenging due to the high sensitivity of thermophilic microbiomes to temperature fluctuations. Here we compare the effects of two decreasing-temperature modes from 55 to 35 °C on cell viability, microbial dynamics, and interspecies interactions. A sharp transition (ST) is a one-step transition by 20 °C d−1, while a mild transition (MT) is a stepwise transition by 1 °C d−1. We find a greater decrease in methane production with ST (88.8%) compared to MT (38.9%) during the transition period. ST mode overproduced reactive oxygen species by 1.6-fold, increased membrane permeability by 2.2-fold, and downregulated microbial energy metabolism by 25.1%, leading to increased apoptosis of anaerobes by 1.9-fold and release of intracellular substances by 2.9-fold, further constraining methanogenesis. The higher (1.6 vs. 1.1 copies per gyrA) metabolic activity of acetate-dependent methanogenesis implied more efficient methane production in a steady mesophilic, MT-mediated system. Metagenomic binning and network analyses indicated that ST induced dysbiosis in keystone species and greatly enhanced microbial functional redundancy, causing loss of microbial syntrophic interactions and redundant metabolic pathways. In contrast, the greater microbial interconnections (average degrees 44.9 vs. 22.1) in MT at a steady mesophilic state suggested that MT could better maintain necessary system functionality and stability through microbial syntrophy or specialized pathways. Adopting MT to transform thermophilic digesters into mesophilic digesters is feasible and could potentially enhance the further optimization and broader application of practical anaerobic engineering.

Influence of community complexity and regulation by two-component system on community stability in aerobic composting in the presence of penicillin residues

Aerobic composting technology offers an effective solution for addressing antibiotic residues. Despite advancements in improving composting materials and understanding microbial community composition, exploring the impacts of residual antibiotics on microbial community complexity, stability, and functionality is essential. In this study, the mechanisms related to the impacts of residual antibiotics were analyzed using chicken manure and straw as raw materials, with residual penicillin at different concentrations as the environmental stressor. High-throughput sequencing technology was employed to reveal the characteristics of the bacterial community. The results showed that compared with the CK group (i.e., without penicillin residue), the FHA group (i.e., with 400 mg/kg penicillin residue) exhibited an increase in network topological features such as nodes (384), edges (17320), average degree (90). Additionally, there was a decrease in modularity (1.69) and the average path length (0.24) and an increase in the species and number of bacteria. These findings collectively indicated a tighter network state, a rich and varied bacterial composition, and closer interspecies interactions in the FHA group, indicating that the initial high concentration of penicillin residue could enhance microbial community complexity. The FHA group exhibited a gradual increase in both robustness and vulnerability compared with the CK group. Additionally, bacterial community cohesion improved from 0.84 to 0.93 by day 35, indicating that the FHA group exhibited the highest level of community stability. The KEGG pathway analysis highlighted the prominent role of two-component systems (TCSs) in community stability, whereas no pathways were found to impact community complexity. In the THA (200 mg/kg penicillin residue) and FHA groups, 36 and 34 differentially expressed TCS genes were identified, respectively. These genes were involved in various functions such as quorum sensing, biofilm formation, and bacterial chemotaxis. In conclusion, the initial high concentration of penicillin residue could enhance both the complexity and stability of the community. Residual penicillin presumably regulated community stability by influencing the differential expression of TCS genes. These findings contribute to a deeper understanding of community stability in aerobic composting, offering insights for optimizing aerobic composting methods.

Inter-species interaction of bradyrhizobia affects their colonization and plant growth promotion in Arachis hypogaea.

Bradyrhizobia are the principal symbiotic partner of the leguminous plant and take active part in biological nitrogen-fixation. The present investigation explores the underlying competition among different strains during colonization in host roots. Six distinct GFP and RFP-tagged Bradyrhizobium strains were engineered to track them inside the peanut roots either independently or in combination. The Bradyrhizobium strains require different time-spans ranging from 4 to 21days post-infection (dpi) for successful colonization which further varies in presence of another strain. While most of the individual strains enhanced the shoot and root dry weight, number of nodules, and nitrogen fixation capabilities of the host plants, no significant enhancement of plant growth and nodulation efficiency was observed when they were allowed to colonize in combinations. However, if among the combinations one strains is SEMIA 6144, the co-infection results in higher growth and nodulation efficiency of the hosts. From the competition experiments it has been found that Bradyrhizobium japonicum SEMIA 6144 was found to be the most dominant strain for effective nodulation in peanut. The extent of biofilm and exopolysaccharide (EPS) production by these isolates, individually or in combinations, were envisaged to correlate whether these parameters have any impact on the symbiotic association. But the extent of colonization, growth-promotion and nitrogen-fixation ability drastically lowered when a strain present together with other Bradyrhizobium strain. Therefore, it is imperative to understand the interaction between two co-inoculating Bradyrhizobium species for nodulation followed by plant growth promotion to develop suitable consortia for enhancing BNF in peanut and possibly for other legumes.

Antibiofilm activity of Prevotella species from the cystic fibrosis lung microbiota against Pseudomonas aeruginosa

It is increasingly recognized that interspecies interactions may modulate the pathogenicity of Pseudomonas aeruginosa during chronic lung infections. Nevertheless, while the interaction between P. aeruginosa and pathogenic microorganisms co-infecting the lungs has been widely investigated, little is known about the influence of other members of the lung microbiota on the infection process. In this study, we focused on investigating the impact of Prevotella species isolated from the sputum of people with cystic fibrosis (pwCF) on biofilm formation and virulence factor production by P. aeruginosa. Screening of a representative collection of Prevotella species recovered from clinical samples showed that several members of this genus (8 out 10 isolates) were able to significantly reduce biofilm formation of P. aeruginosa PAO1, without impact on growth. Among the tested isolates, the strongest biofilm-inhibitory activity was observed for Prevotella intermedia and Prevotella nigrescens, which caused a reduction of up to 90% in the total biofilm biomass of several P. aeruginosa isolates from pwCF. In addition, a strain-specific effect of P. nigrescens on the ability of P. aeruginosa to produce proteases and pyocyanin was observed, with significant alterations in the levels of these virulence factors detected in LasR mutant strains. Overall, these results suggest that non-pathogenic bacteria from the lung microbiota may regulate pathogenicity traits of P. aeruginosa, and possibly affect the outcome of chronic lung infections.

Multi-omics analysis of antagonistic interactions among free-living Pseudonocardia from diverse ecosystems.

Actinomycetes are a phylogenetically diverse bacterial group which are widely distributed across terrestrial and aquatic ecosystems. Within this order, the genus Pseudonocardia and their specialised metabolites have been the focus of previous ecological studies due to their antagonistic interactions with other microorganisms and their mutualistic interactions with insects. However, the chemical ecology of free-living Pseudonocardia remains understudied. This study applies a multi-omics approach to investigate the chemical ecology of free-living actinomycetes from the genus Pseudonocardia. In a comparative genomics analysis, it was observed that the biosynthetic gene cluster family distribution was influenced mainly by phylogenetic distance rather than the geographic or ecological origin of strains. This finding was also observed in the mass spectrometry-based metabolomic profiles of nine Pseudonocardia species isolated from marine sediments and two terrestrial species. Antagonist interactions between these 11 species were examined, and matrix-assisted laser desorption/ionisation-mass spectrometry imaging was used to examine in situ chemical interactions between the Southern Ocean strains and their phylogenetically close relatives. Overall, it was demonstrated that phylogeny was the main predictor of antagonistic interactions among free-living Pseudonocardia. Moreover, two features at m/z 441.15 and m/z 332.20 were identified as metabolites related to these interspecies interactions.

Interspecies Interaction of Bacteria Listeria monocytogenes, Yersinia pseudotuberculosis, and Marine Saprotrophs during Long-Term Culturing in Biofilms.

All bacterial strains studied retained the viability and ability to form both mono- and polycultural biofilms under conditions of long-term culturing in artificial seawater at 6°C and without addition of nutrients. Bacillus sp. and Pseudomonas japonica presumably stimulated the growth and reproduction of the pathogenic bacteria Listeria monocytogenes and Yersinia pseudotuberculosis. Preserved cell viability in a monoculture biofilm for a long period without adding a food source can indicate allolysis. At the same time, in a polycultural biofilm, the metabolites secreted by saprotrophic strains can stimulate the growth of L. monocytogenes and Y. pseudotuberculosis.

We, the Animals: Studying Interspecies Relationships in Never Cry Wolf and Mia and the White Lion

Cinema has undergone multiple shifts in recent times and one of the major shifts is towards the eco cinema, where ecocritical theories, primarily focusing on interspecies relationships are highlighted. These theories also include the basic rights of animals, human’s relationship with animals and nature, and also reject anthropocentric beliefs. In one of his articles titled, “The Human Animal: An Ecocritical View of Animal Imagery in Aldous Huxley’s Brave New World”, Erik Fredriksson argues that, “Ecocriticism begins to see human and non-human nature as interconnected and part of a whole. The distinction between human and animal is questioned and animal stories are examined to illuminate how we think about animals. The idea is also to promote empathy towards animals by highlighting kinship and to break up patterns of anthropocentric thinking.” In this paper, the focus will be on two films based on real-life events, Never Cry Wolf, based on Farley Mowat’s book, and Mia and the White Lion, which talks about the fate of lions in the hands of the canned hunters in South Africa, which will blur the line between reel and real. This paper will also highlight the interspecies interactions and relationships, more specifically, the unconventional interaction between the supposed ‘dangerous and ferocious’ wolves and lions and the two central characters, Tyler and Mia.

Electron-transfer-driven spatial optimisation of anaerobic consortia for efficient methanogenesis: Neglected inductive effect of conductive materials

The inductive effect of conductive materials (CMs) on enhancing methanogenesis metabolism has been overlooked. Herein, we highlight role of CMs in inducing the spatial optimisation of methanogenic consortia by altering the Lewis acid–base (AB) interactions within microbial aggregates. In the presence of CMs and after their removal, the methane production and methane proportion in biogas significantly increase, with no significant difference between the two situations. Analyses of interactions between CMs and extracellular polymer substances (EPSs) with and without D2O reveal that CMs promote release and transfer potential of electron in EPSs, which induce and enhance the role of water molecules being primarily as proton acceptors in the hydrogen bonding between EPSs and water, thereby changing the electron-donor- and electron-acceptor-based AB interactions. Investigations of succession dynamics of microbial communities, co-occurrence networks, and metagenomics further indicate that electron transfer drives the microbial spatial optimisation for efficient methanogenesis through intensive interspecies interactions.

Mutualistic interactions of lactate-producing lactobacilli and lactate-utilizing Veillonella dispar: Lactate and glutamate cross-feeding for the enhanced growth and short-chain fatty acid production.

The human gut hosts numerous ecological niches for microbe-microbe and host-microbe interactions. Gut lactate homeostasis in humans is crucial and relies on various bacteria. Veillonella spp., gut lactate-utilizing bacteria, and lactate-producing bacteria were frequently co-isolated. A recent clinical trial has revealed that lactate-producing bacteria in humans cross-feed lactate to Veillonella spp.; however, their interspecies interaction mechanisms remain unclear. Veillonella dispar, an obligate anaerobe commonly found in the human gut and oral cavity, ferments lactate into acetate and propionate. In our study, we investigated the interaction between V. dispar ATCC 17748T and three representative phylogenetically distant strains of lactic acid bacteria, Lactobacillus acidophilus ATCC 4356T, Lacticaseibacillus paracasei subsp. paracasei ATCC 27216T, and Lactiplantibacillus plantarum ATCC 10241. Bacterial growth, viability, metabolism and gene level adaptations during bacterial interaction were examined. V. dispar exhibited the highest degree of mutualism with L. acidophilus. During co-culture of V. dispar with L. acidophilus, both bacteria exhibited enhanced growth and increased viability. V. dispar demonstrated an upregulation of amino acid biosynthesis pathways and the aspartate catabolic pathway. L. acidophilus also showed a considerable number of upregulated genes related to growth and lactate fermentation. Our results support that V. dispar is able to enhance the fermentative capability of L. acidophilus by presumably consuming the produced lactate, and that L. acidophilus cross-feed not only lactate, but also glutamate, to V. dispar during co-culture. The cross-fed glutamate enters the central carbon metabolism in V. dispar. These findings highlight an intricate metabolic relationship characterized by cross-feeding of lactate and glutamate in parallel with considerable gene regulation within both L. acidophilus (lactate-producing) and V. dispar (lactate-utilizing). The mechanisms of mutualistic interactions between a traditional probiotic bacterium and a potential next-generation probiotic bacterium were elucidated in the production of short-chain fatty acids.

Response and assembly of abundant and rare taxa in Zaopei under different combination patterns of Daqu and pit mud: from microbial ecology to Baijiu brewing microecosystem

The quality and aroma of strong-flavor Baijiu are mainly dependent on Daqu, pit mud (PM), and the interaction of both. However, little is known about how their combination patterns affect the microbiome and metabolome of Zaopei, especially the metabolic function of rare taxa. Here, an experiment on industrial size was designed to assess the effects of 6 combinations (3 kinds of Daqu × 2 kinds of PM) on the composition and assembly of different taxa, as well as the flavor profile. The results showed that Zaopei’s microbiota was composed of a few abundant taxa and enormous rare taxa, and rare bacterial and abundant fungal subcommunities were significantly affected by combination patterns. The assembly processes of abundant/rare taxa and bacterial/fungal communities were distinct, and environmental changes mediated the balance between stochastic and deterministic processes in rare bacteria assembly. Furthermore, specific combination patterns improved the flavor quality of Zaopei by enhancing the interspecies interaction, which was closely related to rare taxa, especially rare bacteria. These findings highlighted that rare bacteria might be the keystone in involving community interaction and maintaining metabolic function, which provided a scientific foundation for better understanding and regulating the brewing microbiota from the viewpoint of microbial ecology.

Kinetics-based inference of environment-dependent microbial interactions and their dynamic variation.

Microbial communities in nature are dynamically evolving as member species change their interactions subject to environmental variations. Accounting for such context-dependent dynamic variations in interspecies interactions is critical for predictive ecological modeling. In the absence of generalizable theoretical foundations, we lack a fundamental understanding of how microbial interactions are driven by environmental factors, significantly limiting our capability to predict and engineer community dynamics and function. To address this issue, we propose a novel theoretical framework that allows us to represent interspecies interactions as an explicit function of environmental variables (such as substrate concentrations) by combining growth kinetics and a generalized Lotka-Volterra model. A synergistic integration of these two complementary models leads to the prediction of alterations in interspecies interactions as the outcome of dynamic balances between positive and negative influences of microbial species in mixed relationships. The effectiveness of our method was experimentally demonstrated using a synthetic consortium of two Escherichia coli mutants that are metabolically dependent (due to an inability to synthesize essential amino acids) but competitively grow on a shared substrate. The analysis of the E. coli binary consortium using our model not only showed how interactions between the two amino acid auxotrophic mutants are controlled by the dynamic shifts in limiting substrates but also enabled quantifying previously uncharacterizable complex aspects of microbial interactions, such as asymmetry in interactions. Our approach can be extended to other ecological systems to model their environment-dependent interspecies interactions from growth kinetics.IMPORTANCEModeling environment-controlled interspecies interactions through separate identification of positive and negative influences of microbes in mixed relationships is a new capability that can significantly improve our ability to understand, predict, and engineer the complex dynamics of microbial communities. Moreover, the prediction of microbial interactions as a function of environmental variables can serve as valuable benchmark data to validate modeling and network inference tools in microbial ecology, the development of which has often been impeded due to the lack of ground truth information on interactions. While demonstrated against microbial data, the theory developed in this work is readily applicable to general community ecology to predict interactions among macroorganisms, such as plants and animals, as well as microorganisms.

Study on the regulatory mechanism of vinegar grains metabolism via different vinegar starters

The application of biofortification technology in regulating the microbial community of Sichuan bran vinegar (SBV) to enhance its quality has garnered significant attention recently. Here, we utilized Cuqu fortified (JQ) by synthetic microbiota composed of two different strains to enhance SBV fermentation, while simultaneously revealing community succession and metabolic regulatory mechanisms. Compared to control samples, the fortified vinegar grains (ZJV) community exhibited a 1.60-fold increase in bacterial biomass during major stages. Dominant fungi dynamics in ZJV significantly shifted, with a notable increase in Monascus and Rasamsonia. Upregulation of enzymes involved in starch and cellulose degradation led to increased contents of volatiles, 4-ethylguaiacol (4-EG), and raw starch conversion rate in the fermented ZJV by 1.75 times, 40 times, and 21.92%, respectively. Biofortification boosted interspecies interactions, clustering functional microbes into a module. Functional bacteria served as connectors, enhancing fungal-bacterial communication, optimizing information and energy exchange, reducing primary metabolite accumulation like ethanol, and improving nutrient utilization and metabolic conversion for secondary metabolite synthesis. These findings establish crucial groundwork for the practical application of synthetic microbiota in various engineering applications.

MicroRNAs from edible plants reach the human gastrointestinal tract and may act as potential regulators of gene expression.

MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that regulate gene expression at the post-transcriptional level. A cross-kingdom regulatory function has been unveiled for plant miRNAs (xenomiRs), which could shape inter-species interactions of plants with other organisms (bacteria and humans) and thus, be key functional molecules of plant-based food in mammals. However, discrepancies regarding the stability and bioavailability of dietary plant miRNAs on the host cast in doubt whether these molecules could have a significant impact on human physiology. The aim of the present study was to identify miRNAs in edible plants and determine their bioavailability on humans after an acute intake of plant-based products. It was found that plant food, including fruits, vegetables and greens, nuts, legumes, and cereals, contains a wide range of miRNAs. XenomiRs miR156e, miR159 and miR162 were detected in great abundance in edible plants and were present among many plant foods, and thus, they were selected as candidates to analyse their bioavailability in humans. These plant miRNAs resisted cooking processes (heat-treatments) and their relative presence increased in faeces after and acute intake of plant-based foods, although they were not detected in serum. Bioinformatic analysis revealed that these miRNAs could potentially target human and bacterial genes involved in processes such as cell signalling and metabolism. In conclusion, edible plants contain miRNAs, such as miR156e, miR159 and miR162, that could resist degradation during cooking and digestion and reach the distal segments of the gastrointestinal tract. Nevertheless, strategies should be developed to improve their absorption to potentially reach host tissues and organs and modulate human physiology.

Growing a Cystic Fibrosis-Relevant Polymicrobial Biofilm to Probe Community Phenotypes.

Most in vitro models lack the capacity to fully probe bacterial phenotypes emerging from the complex interactions observed in real-life environments. This is particularly true in the context of hard-to-treat, chronic, and polymicrobial biofilm-based infections detected in the airways of individuals living with cystic fibrosis (CF), a multiorgan genetic disease. While multiple microbiome studies have defined the microbial compositions detected in the airway of people with CF (pwCF), no in vitro models thus far have fully integrated critical CF-relevant lung features. Therefore, a significant knowledge gap exists in the capacity to investigate the mechanisms driving the pathogenesis of mixed species CF lung infections. Here, we describe a recently developed four-species microbial community model, including Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus sanguinis, and Prevotella melaninogenica grown in CF-like conditions. Through the utilization of this system, clinically relevant phenotypes such as antimicrobialrecalcitrance of several pathogens were observed and explored at the molecular level. The usefulness of this in vitro model resides in its standardized workflow that can facilitate the study of interspecies interactions in the context of chronic CF lung infections.

Interspecies interactions in dairy biofilms drive community structure and response against cleaning and disinfection

Interspecies interactions within a biofilm community influence population dynamics and community structure, which in turn may affect the bacterial stress response to antimicrobials. This study was conducted to assess the impact of interactions between Kocuria salsicia and a three-species biofilm community (comprising Stenotrophomonas rhizophila, Bacillus licheniformis, and Microbacterium lacticum) on biofilm mass, the abundance of individual species, and their survival under a laboratory-scale cleaning and disinfection (C&D) regime. The presence of K. salsicia enhanced the cell numbers of all three species in pairwise interactions. The outcomes derived from summing up pairwise interactions did not accurately predict the bacterial population dynamics within communities of more than two species. In four-species biofilms, we observed the dominance of S. rhizophila and B. licheniformis, alongside a concurrent reduction in the cell counts of K. salsicia and M. lacticum. This pattern suggests that the underlying interactions are not purely non-transitive; instead, a more complex interplay results in the dominance of specific species. We observed that bacterial spatial organization and matrix production in different mixed-species combinations affected survival in response to C&D. Confocal microscopy analysis of spatial organization showed that S. rhizophila localized on the biofilm formed by B. licheniformis and M. lacticum, and S. rhizophila was more susceptible to C&D. Matrix production in B. licheniformis, evidenced by alterations in biofilm mass and by scanning electron microscopy, demonstrated its protective role against C&D, not only for this species itself, but also for neighbouring species. Our findings emphasise that various social interactions within a biofilm community not only affect bacterial population dynamics but also influence the biofilm community's response to C&D stress.

Microbial community structures and bacteria-Cylindrospermopsis raciborskii interactions in Yilong Lake.

Cylindrospermopsis raciborskii-dominated harmful algae blooms have been reported globally in recent years. However, our understanding of the ecology of C. raciborskii in natural conditions is still poor. In this study, we collected the water samples from a C. raciborskii-blooming lake, Yilong Lake, in Yunnan province, China, and used both culture-dependent and culture-independent approaches to investigate their microbial communities and the interactions between C. raciborskii and the other bacteria. The composition and diversity of microbial communities were revealed with 16S rRNA gene high-throughput sequencing data analysis. Microbial co-occurrences analysis suggests C. raciborskii may have complex associations with other bacteria. Based on co-inoculation tests, we obtained 14 strains of bacterial strains from the water samples that exhibited either algicidal or promoting effects on a strain of C. raciborskii. Two bacterial isolates exhibited a consistent performance between co-occurrence analysis and experimental results. Effects of these bacteria-algae interspecies interactions on the bloom event are discussed. All these results may provide new insights into the C. raciborskii-dominated blooms and how its interspecies relationships with other bacteria may influence the bloom events in eutrophic waters throughout the world.

Metastable patterns in one- and two-component dipolar Bose-Einstein condensates

In this paper we study metastable states in single- and two-component dipolar Bose-Einstein condensates. We show that this system supports a rich variety of states that are remarkably stable despite not being ground states. In a parameter region where striped phases are ground states, we find such metastable states that are energetically favorable compared to triangular and honeycomb lattices. Among these metastable states we report a peculiar ring-lattice state, which is led by the competition between triangular and honeycomb symmetries and rarely seen in other systems. In the case of dipolar mixtures we show that via tuning the miscibility these states can be stabilized in a broader domain by utilizing interspecies interactions. Published by the American Physical Society 2024

Type 2 vomeronasal receptor-A4 subfamily: Potential predator sensors in mice.

Sensory signals detected by olfactory sensory organs are critical regulators of animal behavior. An accessory olfactory organ, the vomeronasal organ, detects cues from other animals and plays a pivotal role in intra- and inter-species interactions in mice. However, how ethologically relevant cues control mouse behavior through approximately 350 vomeronasal sensory receptor proteins largely remains elusive. The type 2 vomeronasal receptor-A4 (V2R-A4) subfamily members have been repeatedly detected from vomeronasal sensory neurons responsive to predator cues, suggesting a potential role of this receptor subfamily as a sensor for predators. This review focuses on this intriguing subfamily, delving into its receptor functions and genetic characteristics.

Impacts of tissue context on extracellular vesicles-mediated cancer-host cell communications.

Tumor tissue is densely packed with cancer cells, non-cancerous cells, and ECM, forming functional structures. Cancer cells transfer extracellular vesicles (EVs) to modify surrounding normal cells into cancer-promoting cells, establishing a tumor-favorable environment together with other signaling molecules and structural components. Such tissue environments largely affect cancer cell properties, and so as EV-mediated cellular communications within tumor tissue. However, current research on EVs focuses on functional analysis of vesicles isolated from the liquid phase, including cell culture supernatants and blood draws, 2D-cultured cell assays, or systemic analyses on animal models for biodistribution. Therefore, we have a limited understanding of local EV transfer within tumor tissues. In this review, we discuss the need to study EVs in a physiological tissue context by summarizing the current findings on the impacts of tumor tissue environment on cancer EV properties and transfer and the techniques required for the analysis. Tumor tissue environment is likely to alter EV properties, pose physical barriers, interactions, and interstitial flows for the dynamics, and introduce varieties in the cell types taken up. Utilizing physiological experimental settings and spatial analyses, we need to tackle the remaining questions on physiological EV-mediated cancer-host cell interactions. Understanding cancer EV-mediated cellular communications in physiological tumor tissues will lead to developing interaction-targeting therapies and provide insight into EV-mediated non-cancerous cells and interspecies interactions.