Mobile Hosts Research Articles

Metapopulation heterogeneities in host mobility, productivity, and immunocompetency always increase virulence and infectiousness

Metapopulation heterogeneities in host mobility, productivity, and immunocompetency always increase virulence and infectiousness

Identification and analysis of the genetic diversity of Dermacentor everestianus using mitochondrial 16S rRNA and COI sequences in the Xizang Autonomous Region of China

Ticks serve as vectors and reservoirs for a variety of pathogens, including protozoa, bacteria, and viruses, that cause tick-borne diseases in both humans and livestock. Despite their widespread distribution, their genetic diversity and population structure in Xizang have not been thoroughly investigated. In this study, sheep ticks were identified from four counties by microscopy, followed by genetic analysis of Dermacentor everestianus populations in Xizang based on mitochondrial 16S rRNA and cytochrome oxidase subunit 1 (COI) gene sequences. D. everestianus was the predominant species and 16S rRNA gene sequence analysis revealed nine haplotypes with seven nucleotide variations, showing a mean haplotype diversity (Hd) of 0.505 and mean nucleotide diversity (Pi) of 0.00129. Similarly, the COI sequences revealed 28 haplotypes with 26 nucleotide variations, yielding a mean Hd of 0.828 and a mean Pi of 0.00279. Molecular variance analysis (AMOVA) indicated that most genetic variation occurs within populations. In addition, neutral test analyses suggested potential bottleneck events in the D. everestianus populations. The haplotype network had a star-like distribution with the common haplotypes A1, A2, B1, and B5. The phylogenetic tree separated haplotypes of both genes into two branches on the haplotype network indicating no distinct geographical clustering. This study is the first to highlight the prevalence of D. everestianus in Xizang, revealing moderate genetic differentiation among the four populations, possibly due to host mobility. This intensive investigation of genetic variation and population structure contributes valuable insights into the current population genetics of D. everestianus in Xizang, China.

A male-killing Spiroplasma endosymbiont has age-mediated impacts on Drosophila endurance and sleep

Endosymbiotic bacteria have a wide range of impacts on host physiology, behavior, metabolism, endurance, and mobility. Recent work found some endosymbionts also impact host sleep duration and quality. These effects may increase as flies age and endosymbiont titers increase. We tested the hypothesis that Spiroplasma poulsonni MSRO negatively impacts sleep in Drosophila melanogaster, and this in turn impairs fly endurance. In geotaxis climbing assays (a proxy for endurance), we found that MSRO impacted climbing endurance but in an age-dependent manner. Among younger flies, MSRO+ flies slept significantly less during dark periods (measured by a Drosophila Activity Monitoring System) compared to uninfected flies, but older MSRO+ flies did not show significant differences in amount of sleep compared to uninfected flies in the same cohort. While MSRO status impacted both sleep and endurance of hosts, endosymbiont-mediated sleep deprivation did not directly explain decreases in fly endurance. We discuss these results in the context of endosymbiont comparative biology.

Non-antibiotic disinfectant synchronously interferes methane production and antibiotic resistance genes propagation during sludge anaerobic digestion: Activation of microbial adaptation and reconfiguration of bacteria-archaea synergies

Waste activated sludge (WAS) presents both resource recovery potential and pollution risks, making its efficient treatment challenging. Anaerobic digestion is broadly recognized as a green and sustainable approach to WAS treatment, whose efficiency is easily impacted by the exogeneous pollutants in WAS. However, the impact of polyhexamethylene guanidine (PHMG), as a widely-used non-antibiotic disinfectant, on WAS digestion under semi-continuous flow conditions remains unclear. In this study, CH4 production decreased from 16.1 mL/g volatile suspended solids (VSS) in the control to 13.2 mL/g VSS and 0.3 mL/g VSS under low and high PHMG exposure, respectively, while PHMG increased the number of antibiotic resistance gene (ARG) copies per bacterium by 4.6-12.7 %. Molecular docking analysis revealed that PHMG could spontaneously bind to and disintegrate WAS (binding energy:2.35 and -9.62 kcal/mol), increasing the likelihood of microbial exposure to PHMG. This led to an increase in bacterial abundance and a reduction in archaeal populations, resulting in bacterial dominance in ecological niches. The network topology index in PHMG-treated reactors was consistently lower than in the control, with a higher proportion of negatively correlated links, indicating a more antagonistic relationship between bacteria and archaea. Consequently, PHMG significantly interfered with key genes involved in CH4 biosynthesis (e.g., mch and mtd). Interestingly, methanogenic activity and archaeal chemotaxis (e.g., rfk and cheA) partially recovered under low PHMG exposure due to archaeal adaptation through quorum sensing and two-component systems. However, this adaptation process also contributed to the propagation of ARGs through horizontal gene transfer, facilitated by the enhancement of mobile genetic elements and ARGs hosts. These findings confirm the ecological risks of PHMG and highlight the need for effective WAS disposal strategies.

La Substitution into the Melilite Derivative Ca5Ga6O14: Prediction, Synthesis and Ionic Conductivity.

Melilite-type gallates of general formula RE1+xAE1-xGa3O7+x/2 are of interest for their ability to host mobile interstitial oxide ions in [Ga3O7+x] layers. The crystal structure of Ca5Ga6O14 is closely related to melilite, with [Ga3O7] layers stacked in a more complex way to accommodate an additional 0.5 interlayer cations per formula unit, suggesting the potential for similar oxide ion conduction behavior. We used a computational approach to identify the most promising routes to interstitial oxide incorporation into Ca5Ga6O14, leading to an experimental investigation of the system Ca5-xLaxGa6O14+x/2. Single-phase materials were obtained in the range 0 ≤ x ≤ 0.25 by solid state reactions, producing an ∼40× increase in ionic conductivity at 800 °C. This limited compositional range presents a challenge for characterization of the charge-compensating defects. The La substituents were observed directly by X-ray diffraction and STEM-EDX, and a combination of different structural characterization techniques and DFT calculations indicated the presence of interstitial oxide ions indirectly, explaining the conductivity response. As higher carrier concentrations (x > 0.25) are apparently inaccessible in this system, we conclude that its potential as a useful oxide ion conductor is more limited than that of established melilite materials such as La1+xCa1-xGa3O7+x/2.

A novel solution for routing a swarm of drones operated on a mobile host

The increasing use of drones across various sectors demands optimized deployment strategies under diverse constraints. This paper tackles the Multiple Capacitated Mobile Depot Vehicles Routing Problem (mCMoD-VRP), a challenging variant of the Vehicle Routing Problem (VRP) where multiple drones with limited flight range operate from a mobile depot. The goal is to maximize target coverage while considering flight endurance, depot mobility, and drone multiplicity. We introduce a novel evolutionary algorithm, Evolutionary Optimization for Synchronized Routing Problem (EOSRP), which constructs synchronized routes for the drone swarm, accounting for all constraints. EOSRP distinguishes itself with specialized genetic operators, specifically designed to efficiently handle the constraints of mCMoD-VRP, enhancing both exploration and exploitation of the search space. EOSRP also facilitates collaborative planning among drones, enabling them to share targets and optimize routes collectively, resulting in more efficient use of flight range capacity. Comprehensive simulations on benchmark problems demonstrate that EOSRP consistently outperforms a serialized version of our previous single-drone algorithm, Genetic Algorithm for Capacitated Mobile Depot (GA-CMoD), achieving an average of 8.7% higher target coverage and 7.28% more efficient use of flight range capacity. EOSRP’s ability to generate synchronized solutions through collaborative planning leads to significantly improved mission efficiency.

Pipe material and natural organic matter impact drinking water biofilm microbial community, pathogen profiles and antibiotic resistome deciphered by metagenomics assembly

Biofilms in drinking water distribution systems (DWDSs) are a determinant to drinking water biosafety. Yet, how and why pipe material and natural organic matter (NOM) affect biofilm microbial community, pathogen composition and antibiotic resistome remain unclear. We characterized the biofilms’ activity, microbial community, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and pathogenic ARG hosts in Centers for Disease Control and Prevention (CDC) reactors with different NOM dosages and pipe materials based on metagenomics assembly. Biofilms in cast iron (CI) pipes exhibited higher activity than those in polyethylene (PE) pipes. NOM addition significantly decreased biofilm activity in CI pipes but increased it in PE pipes. Pipe material exerted more profound effects on microbial community structure than NOM. Azospira was significantly enriched in CI pipes and Sphingopyxis was selected in PE pipes, while pathogen (Ralstonia pickettii) increased considerably in NOM-added reactors. Microbial community network in CI pipes showed more edges (CI 13520, PE 7841) and positive correlation proportions (CI 72.35%, PE 61.69%) than those in PE pipes. Stochastic processes drove assembly of both microbial community and antibiotic resistome in DWDS biofilms based on neutral community model. Bacitracin, fosmidomycin and multidrug ARGs were predominant in both PE and CI pipes. Both pipe materials and NOM regulated the biofilm antibiotic resistome. Plasmid was the major MGE co-existing with ARGs, facilitating ARG horizontal transfer. Pathogens (Achromobacter xylosoxidans and Ralstonia pickettii) carried multiple ARGs (qacEdelta1, OXA-22 and aadA) and MGEs (integrase, plasmid and transposase), which deserved more attention. Microbial community contributed more to ARG change than MGEs. Structure equation model (SEM) demonstrated that turbidity and ammonia affected ARGs by directly mediating Shannon diversity and MGEs. These findings might provide a technical guidance for controlling pathogens and ARGs from the point of pipe material and NOM in drinking water.

The influence of social and spatial processes on the epidemiology of environmentally transmitted pathogens in wildlife: implications for management.

Social and spatial structures of host populations play important roles in pathogen transmission. For environmentally transmitted pathogens, the host space use interacts with both the host social structure and the pathogen's environmental persistence (which determines the time-lag across which two hosts can transmit). Together, these factors shape the epidemiological dynamics of environmentally transmitted pathogens. While the importance of both social and spatial structures and environmental pathogen persistence has long been recognized in epidemiology, they are often considered separately. A better understanding of how these factors interact to determine disease dynamics is required for developing robust surveillance and management strategies. Here, we use a simple agent-based model where we vary host mobility (spatial), host gregariousness (social) and pathogen decay (environmental persistence), each from low to high levels to uncover how they affect epidemiological dynamics. By comparing epidemic peak, time to epidemic peak and final epidemic size, we show that longer infectious periods, higher group mobility, larger group size and longer pathogen persistence lead to larger, faster growing outbreaks, and explore how these processes interact to determine epidemiological outcomes such as the epidemic peak and the final epidemic size. We identify general principles that can be used for planning surveillance and control for wildlife host-pathogen systems with environmental transmission across a range of spatial behaviour, social structure and pathogen decay rates. This article is part of the theme issue 'The spatial-social interface: a theoretical and empirical integration'.

Efficient dynamic IP datacasting mobility management based on LRS in mobile IP networks

IP mobility support is based on terminal behavior, recognizing mobility and maintaining a continuous communication session. The existing mobile IP location registration sends a message to one or more routers during a handoff within a domain by using a multicast address to process messages continuously. This implementation requires persistent message processing among all routers to determine new multicast address assignments. To solve this problem, we propose a method that enables the mobile user to obtain a QoS guarantee when the mobile device moves to an overlapping area under the mobile IP. Therefore, dynamic mobility management includes location updates under the mobile IP, and transmission of packets from the expected access points. When a handoff occurs while the mobile device is connected, the mobile host dynamically adapts to the mobility characteristics of the mobile node and transmits missed packets. In addition, by first using a location router, handoff latency reduction and packet loss requirements between domains in the overlapping mobile network environment are resolved. Second, the proposed algorithm has low-control traffic in the mobile network, allowing quick handoffs. Although instantaneous throughput is reduced during handoffs, tunneling is reduced by 10-30%, even after a handoff, by retransmitting packets missed by the mobile host, while location-registration-update times are reduced by 20-80%.

Towards a generic agent-based vector-host model: effects of carrying capacity and host mobility

The aim of our work is to develop a generic conceptual agent-based model to formalize the interaction of vector and host given climate change. The model consists in creating a hypothetical example of a vector-host system. It simulates the vector’s life cycle while considering interactions with hosts and the temperature. It is presented following the ODD protocol and based on parameters and processes to conceptualize the vector-host complexity. It could accommodate a broad spectrum of vector species and different biogeographic regions. Our model can be extended to more ecologically complex systems with multiple species and real-world landscape complexity to test different host and / or vector-targeted control strategies and identify practical approaches to managing vector population and movement patterns.

Host lifestyle and parasite interspecific facilitation mediate co‐infection in a species‐poor host–parasite system

Despite their important ecological role, questions remain on mechanisms structuring parasite assemblages. We present an endemic and species‐poor parasite–host system of two species of clupeid fishes Limnothrissa miodon, Stolothrissa tanganicae) and two species of monogenean parasites (Kapentagyrus, Dactylogyridae) from Lake Tanganyika as a model to study parasite distribution patterns and co‐infection dynamics in nature. We modelled spatiotemporal dynamics of parasite–host interaction using infection data along the north–south axis of Lake Tanganyika (660 km) over the course of two seasons and four years (1730 fish, 3710 parasites). We found temporal stability of parasite infection, which contrasts with previously reported seasonally driven fluctuations of fish host abundances. We found a difference in spatial structure between the parasite species which follows the contrasting dispersal pattern of their respective host species. On L. miodon, the host species that is infected by the two parasite species, we discovered a positive correlation with host body size for one parasite species, and a negative correlation for the other species. The apparent host‐size related replacement in the two parasite species infecting L. miodon contrasts with the beneficial influence that each of the parasite species has on the other. Parasites have been reported in previous studies to change habitat depending on host size/age. Differences in abundance and prevalence here reported between parasite species infecting the same host species related to the host body length further illustrate the parasites' dependence on changes in lifestyle of the host during its ontogenetic development. Also, possible mechanisms underlying the reported facilitation of infection are discussed. In conclusion, we show that in this closed, species‐poor system parasite infection dynamics are dependent on a combination of host mobility, host lifestyle changes over ontogenetic development, and interspecific interactions between parasites.

How frequently are insects wounded in the wild? A case study using Drosophila melanogaster.

Wounding occurs across multicellular organisms. Wounds can affect host mobility and reproduction, with ecological consequences for competitive interactions and predator-prey dynamics. Wounds are also entry points for pathogens. An immune response is activated upon injury, resulting in the deposition of the brown-black pigment melanin in insects. Despite the abundance of immunity studies in the laboratory and the potential ecological and evolutionary implications of wounding, the prevalence of wounding in wild-collected insects is rarely systematically explored. We investigated the prevalence and potential causes of wounds in wild-collected Drosophilidae flies. We found that 31% of Drosophila melanogaster were wounded or damaged. The abdomen was the most frequently wounded body part, and females were more likely to have melanized patches on the ventral abdomen, compared with males. Encapsulated parasitoid egg frequency was approximately 10%, and just under 1% of Drosophilidae species had attached mites, which also caused wounds. Wounding is prevalent in D. melanogaster, likely exerting selection pressure on host immunity for two reasons: on a rapid and efficient wound repair and on responding efficiently to opportunistic infections. Wounding is thus expected to be an important driver of immune system evolution and to affect individual fitness and population dynamics.

A matter of connection: the importance of habitat networks for endangered butterflies in anthropogenic landscapes

Cities are expanding at fast rates across the world, representing one of the main drivers of biodiversity loss due to habitat replacement. Nonetheless, urban and peri-urban areas often feature green spaces that may offer opportunities to wildlife and even represent safe havens for endangered species. Nonetheless, the key drivers that shape wildlife responses to urban landscapes, and in turn their ability to persist within cities, are far from being fully understood. Here we focus on an ecologically specialized butterfly, the endemic Italian festoon Zerynthia cassandra, as a model to assess how endangered species may survive in highly modified urban landscapes. The relatively low mobility and high host plant specialization make Z. cassandra an excellent target for studies in urban ecology, as they make the species able to exploit small suitable patches while at the same time potentially sensitive to habitat fragmentation and loss due to urbanization and land reclamation. We thus first document the relatively widespread occurrence of potentially suitable sites within two highly modified landscapes of central and southern Italy, with 25 and 35% of sites actually occupied by Z. cassandra. By modeling the probability of butterfly occurrence as a function of environmental characteristics, we found that Z. cassandra is strongly influenced by functional connectivity among suitable sites in urban landscapes, as well as by the abundance of Aristolochia host plants, and by the availability of profitable land cover classes in the immediate surroundings of potential oviposition sites. Our results indicate not only that networks of urban and peri-urban green spaces may host populations of protected and endangered species, but that management should also focus on the urban matrix in order to provide connecting corridors, as key assets to guarantee species persistence in cities.

A Survey on Security Mechanisms in D2D IoT Networks

Due to the availability of handheld, mobile devices and the advent of cloud and bog data applications, the data traffic in the licensed bands has increased. This has led to the exploration of alternative avenues to de-load the conventional wireless networks. A new paradigm called device to device networks has evolved which is a category of mobile ad-hoc networks. Device-to- device (D2D) communication is expected to play a significant role in upcoming networks as it will reduce the burden from the cellular systems. This may make big data applications easier. However the D2D networks don’t use the security provided by cellular networks. Hence there is a chance of attacks. The major attack in D2D devices is the eavesdropping attack in which mobile hosts share the same wireless medium and broadcast signals over airwaves, which can be easily intercepted by receivers tuned to the proper frequency. Thus, the attacker can read exchanged messages and is able to inject fake messages to manipulate other users. This paper investigates the salient approaches of D2D networks in the context of security and access control and existing research methods. Keywords: Internet of Things (IoT), Network Security, D2D Security, Throughput, Error Rate.

IoT energy efficiency routing protocol using FHO‐based clustering and improved CSO model‐based routing in MANET

SummaryMany protocols, services, and electrical devices with built‐in sensors have been developed in response to the rapid expansion of the Internet of Things. Mobile ad hoc networks (MANETs) consist of a collection of autonomous mobile nodes that can form an ad hoc network in the absence of any pre‐existing infrastructure. System performance may suffer due to the changeable topology of MANETs. Since most mobile hosts operate on limited battery power, energy consumption poses the biggest challenge for MANETs. Both network lifetime and throughput improve when energy usage is reduced. However, existing approaches perform poorly in terms of energy efficiency. Scalability becomes a significant issue in large‐scale networks as they grow, leading to overhead associated with routing updates and maintenance that can become unmanageable. This article employs a MANET routing protocol combined with an energy conservation strategy. The clustering hierarchy is used in MANETs to maximize the network's lifespan, considering its limited energy resources. In the MANET communication process, the cluster head (CH) is selected using Fire Hawk Optimization (FHO). When choosing nodes to act as a cluster for an extended period, CH election factors in connectivity, mobility, and remaining energy. This process is achieved using an optimized version of the Ad hoc On‐Demand Distance Vector (AODV) routing protocol, utilizing Improved Chicken Swarm Optimization (ICSO). In comparison to existing protocols and optimization techniques, the proposed method offers an extended network lifespan ranging from 90 to 160 h and reduced energy consumption of 80 to 110 J, as indicated by the implementation results.

Evolution of infectious diseases induced by epidemic prevention publicity and interaction between heterogeneous strains

<p>The spread of viruses can be effectively reduced by the publicity of epidemic prevention. Additionally, the interaction between heterogeneous strains has a significant effect on virus evolution. Thus, we first establish an evolutionary dynamics Susceptible-Infected- Recovered (SIR) model which considers the interaction between heterogeneous strains. We utilize adaptive dynamics to investigate the evolutionary outcomes of the trade-off between transmission and virulence. Second, we perform a critical function analysis to generalize the results independent of specific trade-off assumptions and to determine the conditions for evolutionary stability and convergence stability. Last, we investigate the effects of different publicity measures on virulence evolution under two types of interactions, including the case of excess mortality alone and the coexistence of excess mortality and superinfection. Based on the general hypothesis of transmission virulence trade-off, we introduce the cost of host mobility caused by the scope and intensity of publicity. Numerical simulations present a set of evolutionary results, including continuously stable strategies, evolutionary branching points, repellers, and the Garden of Eden. Our results indicate that an excessive publicity scope and intensity can drive the epidemic evolution towards higher virulence. Both types of interactions suggest that continuously increasing the publicity scope under a low publicity intensity can effectively reduce virulence. Furthermore, the concurrent presence of excess mortality and superinfection induces the emergence of a higher virulence.</p>

A high-performance hyperfluorescent device through host optimization

The unsatisfied feature in the operating lifetime and efficiency has hindered the wide application of hyperfluorescent organic light emitting diodes (OLEDs). In order to achieve high efficiency and long lifetime, it is necessary to ensure the stability of the emitting layer (EML) while maintaining high exciton utilization. However, this faces enormous challenges. Our research reveals the impact of host characteristics on the efficiency and lifetime, in a typical hyperfluorescent system. The experimental results show that the carrier mobility and triplet states (T1) of host seriously affect device performance. Strategically adjusting exciton recombination through host selection, can help achieve an efficient and stable device. In addition, the stability of assistant layers adjacent to EML, also has influence on the lifetime of the devices. On this basis, a high-performance green hyperfluorecent device was fabricated, with a maximum efficiency of 227.7 cd A−1. The LT95 (brightness attenuation to 95%) lifetime of such device achieved to 410 h with an initial brightness of 31338 cd m−2, creating a new record. The performance of this hyperfluoresent OLED has reached the same level as the latest generation of commercial phosphorescent devices. More than that, the color of CIE-1931 (0.205, 0.757) of the device well meets the requirement of Adobe standard for green. In addition, a low efficiency roll-off of 1.07%, from maximum efficiency to efficiency at 10 mA cm−2, was observed, which helped to reduce the power consumption of OLED high gray display.The purposeful adjustment of the position and width of exciton recombination region by a well-chosen host, is considered the main reason for achieving such excellent performance. This study systematically reveals the influence of host on OLEDs based on thermally activated delayed fluorescence (TADF), and shows a great possibility of the technology in practical application.

Effects of disinfectant type and dosage on biofilm's activity, viability, microbiome and antibiotic resistome in bench-scale drinking water distribution systems

Drinking water distribution systems (DWDSs) are important for supplying high-quality water to consumers and disinfectant is widely used to control microbial regrowth in DWDSs. However, the disinfectant's influences on microbial community and antibiotic resistome in DWDS biofilms and the underlying mechanisms driving their dynamics remain elusive. The study investigated the effects of chlorine and chloramine disinfection on the microbiome and antibiotic resistome of biofilms in bench-scale DWDSs using metagenomics assembly. Additionally, the biofilm activity and viability were monitored based on adenosine triphosphate (ATP) and flow cytometer (FCM) staining. The results showed that both chlorine and chloramine disinfectants decreased biofilm ATP, although chloramine at a lower dosage (1 mg/L) could increase it. Chloramine caused a greater decrease in living cells than chlorine. Furthermore, the disinfectants significantly lowered the microbial community diversity and altered microbial community structure. Certain bacterial taxa were enriched, such as Mycobacterium, Sphingomonas, Sphingopyxis, Azospira, and Dechloromonas. Pseudomonas aeruginosa exhibited high resistance towards disinfectants. The disinfectants also decreased the complexity of microbial community networks. Some functional taxa (e.g., Nitrospira, Nitrobacter, Nitrosomonas) were identified as keystones in chloramine-treated DWDS microbial ecological networks. Stochasticity drove biofilm microbial community assembly, and disinfectants increased the contributions of stochastic processes. Chlorine had greater promotion effects on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and ARG hosts than chloramine. The disinfectants also selected pathogens, such as Acinetobacter baumannii and Klebsiella pneumonia, and these pathogens also harbored ARGs and MGEs. Overall, this study provides new insights into the effects of disinfectants on biofilm microbiome and antibiotic resistome, highlighting the importance of monitoring and managing disinfection practices in DWDSs.

Hazardous risk of antibiotic resistance genes: Host occurrence, distribution, mobility and vertical transmission from different environments to corn silage

Antibiotic resistance genes (ARGs) are one of the emerging contaminants posing a great deal of hazardous risk to public health. This study employed metagenomics and deciphered the potential risk of the antibiotic resistome and their vertical transfer to ensiled whole-crop corn silage harvested from six climate zones: 1. Warm temperate-fully humid-hot summer (Cfa), 2. Arid-desert-cold arid (BWk), 3. Snow-desert-cold summer (Dwc), 4. Snow-desert-hot summer (Dwa), 5. Arid-steppe-cold arid (BSk), and 6. Equatorial-desert (Aw) based on the Köppen-Geiger climate classification in China. The findings demonstrate a high diversity of ARGs, which is related to the drug classes of tetracycline, ciprofloxacin, lincosamide, fosfomycin, and beta lactam. Resistome variations are mostly related to variations in microbial composition and fermentation characteristics of the silages from different climate zones, which are indirectly influenced by environmental conditions. The most dominating ARGs in corn silage were tetM, acrA, H-NS, lnuA, emrR, and KpnG, which is primarily hosted by Klebsiella and Lactobacilli. There were 5 high-risk ARGs (tetM, bacA, SHV-1, dfrA17, and QnrS1) in silage from different climate zones, and the tetM was the most prevalent high-risk ARG. However, throughout the ensiling process, the abundance of ARGs, and mobile ARGs were reduced. The resistome contamination in silage from Tibet (Dwc) with high altitude and harsh environment was relatively low due to the low variety and abundance of ARGs, the low abundance of mobile ARGs and high-risk ARGs. In addition, most of the bacteria responsible for the silage fermentation were also found to be the hosts to the ARGs, although their abundance decreased after 90 d of silage fermentation. Hence, we alert the existence of ARGs-related biosafety risk in silages and call for more attention to the silage ARGs, their hosts, and mobile genetic elements in order to curtail their possible risk to public health.

Toxoplasma gondii in small mammals in Romania: the influence of host, season and sampling location

BackgroundToxoplasma gondii is a protozoan parasite that infects a large spectrum of warm-blooded animals, including humans. Small rodents and insectivores play an important role in the epidemiology of T. gondii and may serve as a source of infection for both, domestic and wild definitive felid hosts. Factors influencing the occurrence of T. gondii in wild small mammals are unknown, despite the fact that many intermediate host species are identified. We have used small mammals (Rodentia and Lipotyphla) captured over two years in various habitats, both in urbanised and in natural landscapes. We assessed the importance of land-use, season and host ecology on T. gondii infection.ResultsWe examined 471 individuals belonging to 20 small mammal species, collected at 63 locations spread over wide altitude, habitat and land-use ranges from Romania. Heart tissue samples were individually analysed by PCR targeting the 529 bp repetitive DNA fragment of T. gondii. The overall prevalence of infection was 7.3%, with nine species of rodents and two species of shrews being found to carry T. gondii DNA. Five species showed high frequency of infection, with the highest prevalence found in Myodes glareolus (35.5%), followed by Spermophilus citellus (33.3%), Sorex minutus (23.1%), S. araneus (21.7%) and Micromys minutus (11.1%). Adults seemed more often infected than young, however when controlling for season, the difference was not significant, as in spring both adults and young showed higher infection rates, but more adults were sampled. Contrary to our expectations, urban/rural areas (with their implicit high density of domestic feline presence) had no effect on infection prevalence. In addition, neither habitat, nor land-use at sampling sites was important as only geographical location and host species were contributing factors to the infection risk.ConclusionsHigh prevalence of T. gondii infection showed a highly localised, patchy occurrence, with long living and higher mobility host species being the most common carriers, especially during autumn.