A cluster of X-linked miRNAs are de-repressed with age in mouse liver and target growth hormone signaling.

Growth hormone (GH) signaling influences lifespan in a wide variety of mammalian species. We previously reported that a cluster of miRNAs located on the X-chromosome are de-repressed with age in male mouse liver, and a subset, the mir-465 family, can directly attenuate expression of the growth hormone receptor (GHR) in vitro leading to a reduction in GH signaling. Here we show that this cluster of miRNAs is also upregulated in the liver with age in females, and that calorie restriction and the Ames dwarf genotype, both known to delay aging, attenuate the upregulation of the miRNA cluster. Upregulation of mir-465 in vivo leads to a reduction in GHR mRNA in the liver and an attenuation of GH signaling, indicated by a reduction in GHR, IGF-1, IGFBP3, and ALS mRNA expression. There is a corresponding reduction in IGF-1 protein levels in the liver and plasma. These results suggest that the age-associated upregulation of the X-chromosomal cluster of miRNAs could influence lifespan.

Combination of High-Throughput Screening and Assembly to Discover Efficient Metal-Organic Frameworks on Kr/Xe Adsorption Separation.

Recycling Kr and Xe from used nuclear fuel (UNF) is conducive to regenerating economy and protecting the environment, and it is urgent to screen or design high-performance cutting-edge metal-organic framework (MOF) materials for Kr/Xe adsorption separation. After grand canonical Monte Carlo (GCMC) simulations of Kr/Xe adsorption separation on 11,000 frameworks in CoRE MOFs (2019), the important structure-adsorption property relationship (SAPR) was induced; that is, the porosity (φ) at 0.30-0.40, LCD/PLD at 1.00-1.49, density (ρ) range between 1.20 and 2.30 g/cm3, and PLD at 2.40-3.38 Å can be utilized to screen for high-performance G-MOFs and hMOFs. In addition, the key "genes" (metal nodes and linkers) of MOFs determining the Kr/Xe adsorption separation were data-mined by a machine learning technique, which were assembled into novel MOFs. After comprehensive consideration of thermal stability and the adsorbent performance score (APS), eight promising MOFs on Kr/Xe separation with the APS more than 1290.89 were screened out and assembled, which are better than most of the reported frameworks. Note that the adsorption isotherms of these MOFs on Kr and Xe belong to type I curve with the thermodynamic equilibrium mechanism on Kr/Xe based on the confinement effect. Furthermore, according to the electronic structure calculations of the independent gradient model based on Hirshfeld partition (IGMH) and energy decomposition analysis, it is found that the interactions between guests and frameworks are vdW forces with dominant induction energy (Eind). In addition, the electrostatic potential gradients of frameworks are generally linearly negative correlated with Kr uptakes. Therefore, both the geometrical and electronic structures dominate the adsorption separation performance on Kr/Xe. Interestingly, these eight MOFs are also suitable for the separation of CH4/H2 with considerable selectivities and CH4 uptakes of up to 2566.67 and 3.04 mmol/g, respectively. Herein, the accurately constructed SAPR and material genomics strategy should be helpful for the experimental discovery of novel MOFs on Kr/Xe separation experimentally.

Association between Neuroligin-1 polymorphism and plasma glutamine levels in individuals with autism spectrum disorder.

BACKGROUND: Unravelling the relationships between candidate genes and autism spectrum disorder (ASD) phenotypes remains an outstanding challenge. Endophenotypes, defined as inheritable, measurable quantitative traits, might provide intermediary links between genetic risk factors and multifaceted ASD phenotypes. In this study, we sought to determine whether plasma metabolite levels could serve as endophenotypes in individuals with ASD and their family members. METHODS: We employed an untargeted, high-resolution metabolomics platform to analyse 14,342 features across 1099 plasma samples. These samples were collected from probands and their family members participating in the Autism Genetic Resource Exchange (AGRE) (N = 658), compared with neurotypical individuals enrolled in the PrecisionLink Health Discovery (PLHD) program at Boston Children's Hospital (N = 441). We conducted a metabolite quantitative trait loci (mQTL) analysis using whole-genome genotyping data from each cohort in AGRE and PLHD, aiming to prioritize significant mQTL and metabolite pairs that were exclusively observed in AGRE. FINDINGS: Within the AGRE group, we identified 54 significant associations between genotypes and metabolite levels (P < 5.27 × 10-11), 44 of which were not observed in the PLHD group. Plasma glutamine levels were found to be associated with variants in the NLGN1 gene, a gene that encodes post-synaptic cell-adhesion molecules in excitatory neurons. This association was not detected in the PLHD group. Notably, a significant negative correlation between plasma glutamine and glutamate levels was observed in the AGRE group, but not in the PLHD group. Furthermore, plasma glutamine levels showed a negative correlation with the severity of restrictive and repetitive behaviours (RRB) in ASD, although no direct association was observed between RRB severity and the NLGN1 genotype. INTERPRETATION: Our findings suggest that plasma glutamine levels could potentially serve as an endophenotype, thus establishing a link between the genetic risk associated with NLGN1 and the severity of RRB in ASD. This identified association could facilitate the development of novel therapeutic targets, assist in selecting specific cohorts for clinical trials, and provide insights into target symptoms for future ASD treatment strategies. FUNDING: This work was supported by the National Institute of Health (grant numbers: R01MH107205, U01TR002623, R24OD024622, OT2OD032720, and R01NS129188) and the PrecisionLink Biobank for Health Discovery at Boston Children's Hospital.

Domain Adaptation for Underwater Image Enhancement.

Recently, learning-based algorithms have shown impressive performance in underwater image enhancement. Most of them resort to training on synthetic data and obtain outstanding performance. However, these deep methods ignore the significant domain gap between the synthetic and real data (i.e., inter-domain gap), and thus the models trained on synthetic data often fail to generalize well to real-world underwater scenarios. Moreover, the complex and changeable underwater environment also causes a great distribution gap among the real data itself (i.e., intra-domain gap). However, almost no research focuses on this problem and thus their techniques often produce visually unpleasing artifacts and color distortions on various real images. Motivated by these observations, we propose a novel Two-phase Underwater Domain Adaptation network (TUDA) to simultaneously minimize the inter-domain and intra-domain gap. Concretely, in the first phase, a new triple-alignment network is designed, including a translation part for enhancing realism of input images, followed by a task-oriented enhancement part. With performing image-level, feature-level and output-level adaptation in these two parts through jointly adversarial learning, the network can better build invariance across domains and thus bridging the inter-domain gap. In the second phase, an easy-hard classification of real data according to the assessed quality of enhanced images is performed, in which a new rank-based underwater quality assessment method is embedded. By leveraging implicit quality information learned from rankings, this method can more accurately assess the perceptual quality of enhanced images. Using pseudo labels from the easy part, an easy-hard adaptation technique is then conducted to effectively decrease the intra-domain gap between easy and hard samples. Extensive experimental results demonstrate that the proposed TUDA is significantly superior to existing works in terms of both visual quality and quantitative metrics.

Wild birds-the sentinel of antibiotic resistance for urban river: Study on egrets and Jinjiang river in Chengdu, China.

Antibiotic resistance has become a comprehensive and complicated environmental problem. It is of great importance to effectively determine the abundance of various antibiotic resistance genes (ARGs) in the environment. Here, we attempted to find a practical method for monitoring environmental antibiotic resistance. The results of culture-based analysis of antibiotic resistance and metagenomic sequencing indicate that egrets inhabiting along the urban river (Jinjiang River) can be used as the sentinel of environmental antibiotic resistance. The antibiotic resistance in the environment fluctuated with time, while that in the wild bird was relatively stable. The network analysis based on metagenomic sequencing data gave the co-occurrence pattern of ARGs. The overall situation of the antibiotic resistance in the river was determined by quantifying several module hub genes of the co-occurrence network in river sediments. The temporal and spatial distribution of ARGs in Jinjiang River is highly correlated with that of human gut-specific bacteriophage (crAssphage), which indicates that one main source of the antibiotic resistance in the river is likely to be municipal sewage. The mobility potential of ARGs varying among different niches suggests the transmission direction of antibiotic resistance in the environment.

The mystery of Ph3PS revealed in magic-size Ag-S cluster nucleation.

The synthesis of atomically precise semiconductors Ag-S clusters is a subject of intense research interest, yet the formation mechanism of such nanoclusters remains obscure due to their uncontrolled fast nucleation process in solution. Herein, we have investigated the reaction mechanism responsible for {Ag32S3} nucleation using UV, ESI-MS, NMR and SCXRD analyses. Triphenylphosphorus sulfide (PPh3S) was surprisingly found to slow down the kinetic process of the cluster nucleation. Furthermore, a key precursor [Ag2(Ph3PS)4]2+ was captured, which was attacked by Agn(CCBut)m and traces of water to generate {Ag32S3}. This mechanism provides valuable new insights into the synthesis of inorganic magic-size clusters.

Extensive sampling of Saccharomyces cerevisiae in Taiwan reveals ecology and evolution of predomesticated lineages.

The ecology and genetic diversity of the model yeast Saccharomyces cerevisiae before human domestication remain poorly understood. Taiwan is regarded as part of this yeast's geographic birthplace, where the most divergent natural lineage was discovered. Here, we extensively sampled the broadleaf forests across this continental island to probe the ancestral species' diversity. We found that S. cerevisiae is distributed ubiquitously at low abundance in the forests. Whole-genome sequencing of 121 isolates revealed nine distinct lineages that diverged from Asian lineages during the Pleistocene, when a transient continental shelf land bridge connected Taiwan to other major landmasses. Three lineages are endemic to Taiwan and six are widespread in Asia, making this region a focal biodiversity hotspot. Both ancient and recent admixture events were detected between the natural lineages, and a genetic ancestry component associated with isolates from fruits was detected in most admixed isolates. Collectively, Taiwanese isolates harbor genetic diversity comparable to that of the whole Asia continent, and different lineages have coexisted at a fine spatial scale even on the same tree. Patterns of variations within each lineage revealed that S. cerevisiae is highly clonal and predominantly reproduces asexually in nature. We identified different selection patterns shaping the coding sequences of natural lineages and found fewer gene family expansion and contractions that contrast with domesticated lineages. This study establishes that S. cerevisiae has rich natural diversity sheltered from human influences, making it a powerful model system in microbial ecology.

Antibiotics in mariculture systems: A review of occurrence, environmental behavior, and ecological effects.

Antibiotics are widely applied to prevent and treat diseases occurred in mariculture. The often-open nature of mariculture production systems has led to antibiotic residue accumulation in the culturing and adjacent environments, which can adversely affect aquatic ecosystems, and even human. This review summarizes the occurrence, environmental behavior, and ecological effects of antibiotics in mariculture systems based on peer-reviewed papers. Forty-five different antibiotics (categorized into ten groups) have been detected in mariculture systems around the world, which is far greater than the number officially allowed. Indiscriminate use of antibiotics is relatively high among major producing countries in Asia, which highlights the need for stricter enforcement of regulations and policies and effective antibiotic removal methods. Compared with other environmental systems, some environmental characteristics of mariculture systems, such as high salinity and dissolved organic matter (DOM) content, can affect the migration and transformation processes of antibiotics. Residues of antibiotics favor the proliferation of antibiotic resistance genes (ARGs). Antibiotics and ARGs alter microbial communities and biogeochemical cycles, as well as posing threats to marine organisms and human health. This review may provide a valuable summary of the effects of antibiotics on mariculture systems.

Reversing Antibiotic Resistance Caused by Mobile Resistance Genes of High Fitness Cost.

The reversibility of antibiotic resistance is theoretically attractive due to the prospect of restoring the clinical potency of antibiotics. It is important to find out the factors that affect the reversibility of antibiotic resistance. Here, an mcr-1-positive multidrug-resistant (MDR) environmental Escherichia coli isolate was successively passaged under four antibiotic-free culture conditions. The relative abundances of multiple antibiotic resistance genes (ARGs) kept decreasing during the successive passages. The linear correlations between abundances of ARGs on the same MDR plasmid reflected that the decay of antibiotic resistance during the passage was mainly due to the elimination of the MDR plasmid (pMCR_W5-6). Colistin-susceptible strains were isolated at the end of the passage. The whole-genome sequencing of two susceptible isolates detected the elimination of the MDR plasmid and deletion of the mcr-1 gene. Deletions of DNA fragments from chromosome and plasmid were closely related to a variety of insertion sequences (ISs). The results of coculture of resistant and susceptible strains at different antibiotic concentrations indicated that the high fitness cost led to the poor stability of mobile ARGs. Strict control of the use of antibiotics can at least reverse the severe antibiotic resistance caused by mobile ARGs of high fitness cost. IMPORTANCE The dissemination of bacterial antibiotic resistance is a serious threat to human health. The development of new antibiotics faces both economic and technological challenges. The reversibility of antibiotic resistance has become an important issue causing wide concern due to the prospect of restoring the clinical potency of antibiotics. Our study suggests that the high mobility of ARGs of high fitness cost may just reflect their poor stability. Therefore, strict control of the use of antibiotics can at least reverse the severe antibiotic resistance caused by mobile ARGs of high fitness cost. This study brings hope for the possibility of curbing the dissemination of antibiotic resistance.

Technical framework for wastewater-based epidemiology of SARS-CoV-2.

Wastewater-based epidemiology (WBE) is expected to become a powerful tool to monitor the dissemination of SARS-CoV-2 at the community level, which has attracted the attention of scholars all over the world. However, there is not yet a standard protocol to guide its implementation. In this paper, we proposed a comprehensive technical and theoretical framework of relative quantification via qPCR for determining the virus abundance in wastewater and estimating the infection ratio in corresponding communities, which is expected to achieve horizontal and vertical comparability of the data using a human-specific biomarker as the internal reference. Critical factors affecting the virus detectability and the estimation of infection ratio include virus concentration methods, lag-period, per capita virus shedding amount, sewage generation rate, temperature-related decay kinetics of virus/biomarker in wastewater, and hydraulic retention time (HRT), etc. Theoretical simulation shows that the main factors affecting the detectability of virus in sewage are per capita virus shedding amount and sewage generation rate. While the decay of SARS-CoV-2 RNA in sewage is a relatively slow process, which may have limited impact on its detection. Under the ideal condition of high per capita virus shedding amount and low sewage generation rate, it is expected to detect a single infected person within 400,000 people.

Toxicity evaluation of butyl acrylate on the photosynthetic pigments, chlorophyll fluorescence parameters, and oxygen evolution activity of Phaeodactylum tricornutum and Platymonas subcordiformis.

Butyl acrylate is a hazardous and noxious substance (HNS) listed in the top 50 chemicals that is most likely to be involved in HNS spilling incident. At present, information about toxicity effect of butyl acrylate on marine organisms was insufficient, especially on marine microalgae. Phaeodactylum tricornutum (P. tricornutum) and Platymonas subcordiformis (P. subcordiformis) were used as test organism to evaluate the toxic effect of butyl acrylate on their photosynthetic system. Results showed that chlorophyll a (Chl-a) content, the net photosynthetic oxygen evolution rate (NOR), and chlorophyll fluorescence parameters including maximal photochemical efficiency (Fv/Fm), electron transfer rate (ETR), photochemical quenching (qP), and non-photochemical quenching (NPQ) were all stimulated in the toxic dose of 5,10, and 25 mg/L while those were significantly inhibited in the highest concentration of 25 mg/L groups after 96 h. Meanwhile, it was also found that Fv/Fm would be a suitable indicator for evaluating the toxicity of butyl acrylate on the photosynthetic system of two marine microalgae according to the analysis of Pearson correlation coefficient and integrated biomarker response (IBR). Once butyl acrylate enters the marine ecosystem, the toxicity data obtained in this study could be used as a reference for evaluating the effect of butyl acrylate on the photosynthetic capacity of marine microalgae.

WEScover: selection between clinical whole exome sequencing and gene panel testing.

BACKGROUND: Whole exome sequencing (WES) is widely adopted in clinical and research settings; however, one of the practical concerns is the potential false negatives due to incomplete breadth and depth of coverage for several exons in clinically implicated genes. In some cases, a targeted gene panel testing may be a dependable option to ascertain true negatives for genomic variants in known disease-associated genes. We developed a web-based tool to quickly gauge whether all genes of interest would be reliably covered by WES or whether targeted gene panel testing should be considered instead to minimize false negatives in candidate genes. RESULTS: WEScover is a novel web application that provides an intuitive user interface for discovering breadth and depth of coverage across population-scale WES datasets, searching either by phenotype, by targeted gene panel(s) or by gene(s). Moreover, the application shows metrics from the Genome Aggregation Database to provide gene-centric view on breadth of coverage. CONCLUSIONS: WEScover allows users to efficiently query genes and phenotypes for the coverage of associated exons by WES and recommends use of panel tests for the genes with potential incomplete coverage by WES.

Acute toxic effect of typical chemicals and ecological risk assessment based on two marine microalgae, Phaeodactylum tricornutum and Platymonas subcordiformis.

With the increasing demand for typical hazardous and noxious substances (HNS) in chemical industry, there is an increased leakage risk of these HNS during transportation by vessel and storage nearby seashore. In this study, the acute toxicity of nonylphenol, butyl acrylate and 1, 2-dichloroethane to Phaeodactylum tricornutum (P. tricornutum) and Platymonas subcordiformis (P. subcordiformis), was investigated to assess their ecological risk. The results showed that the three kinds of HNS showed significant time- and dose-dependent patterns on the growth inhibition of two marine microalgae. The 96 h-EC50 of nonylphenol, butyl acrylate and 1, 2-dichloroethane on P. tricornutum was 1.088, 45.908 and 396 mg L-1, respectively, and the 96 h-EC50 of that on P. subcordiformis was 0.851, 52.621 and 389 mg L-1, respectively. It was a common method to evaluate the harm of pollutants to organisms by calculating HC5 value (the minimum pollutant concentration value harmful to 95 % of the studied species, which was no-effect concentration) with Species Sensitivity Distribution (SSD). On the basis of EC50, the ecological risk assessment was further carried out, and HC5 value of nonylphenol and 1, 2-dichloroethane to aquatic organism was 0.079 and 44 mg L-1, respectively.

The rectal mucosal but not fecal microbiota detects subclinical ulcerative colitis.

Ulcerative colitis (UC), a subtype of inflammatory bowel disease, is characterized by repetitive remission and relapse. Gut microbiome is critically involved in pathogenesis of UC. The shifts in microbiome profile during disease remission remain under-investigated. Recent studies revealed that UC pathogenesis is likely to originate in the mucosal barrier. Therefore, we investigated the effectiveness of mucosal tissue microbiomes to differentiate patients with subclinical UC from healthy individuals. The microbiomes of cecal and rectal biopsies and feces were characterized from 13 healthy individuals and 45 patients with subclinical UC. Total genomic DNA was extracted from the samples, and their microbial communities determined using next-generation sequencing. We found that changes in relative abundance of subclinical UC were marked by a decrease in Proteobacteria and an increase in Bacteroidetes phyla in microbiome derived from rectal tissues but not cecal tissue nor feces. Only in the microbiome of rectal tissue had significantly higher community richness and evenness in subclinical UC patients than controls. Twenty-seven operational taxonomic units were enriched in subclinical UC cohort with majority of the taxa from the Firmicutes phylum. Inference of putative microbial functional pathways from rectal biopsy microbiome suggested a differential increase in interleukin-17 signaling and T-helper cell differentiation pathways. Rectal biopsy tissue was suggested to be more suitable than fecal samples for microbiome assays to distinguish patients with subclinical UC from healthy adults. Assessment of the rectal biopsy microbiome may offer clinical insight into UC disease progression and predict relapse of the diseases.

Toxic effect of p-chloroaniline and butyl acrylateon Nannochloropsis oculata based on water samples from two sea areas.

To compare the influence of water samples collected from various areas on toxic effect of HNS, we examined the toxic effect of two commonly found HNS: p-chloroaniline and butyl acrylate, on Nannochloropsis oculata cultured in seawater collected from Laizhou bay and Jiaozhou bay (China). The results showed that both p-chloroaniline and butyl acrylate had significant toxic effect on N. oculata cultured in both water samples. P-chloroaniline inhibited its net oxygenation rate and oxygen consumption rate. Butyl acrylate inhibited the net oxygenation rate whereas significantly stimulated oxygen consumption rate. Performance of N. oculata changed between two water samples under same level of p-chloroaniline and butyl acrylate. The net oxygenation rate of N. oculata cultured in the seawater from the Jiaozhou bay increased by 11.60 %, the oxygen consumption rate increased by 26.91 %, algae cell growth decreased by 16.83 %, compared to those from Laizhou bay. The Fv/Fm of N. oculata cultured in Jiaozhou bay was more significantly inhibited at 0.5 and 2.0 mg L-1 p-chloroaniline, while it was significantly inhibited at 5. 0 mg L-1 of butyl acrylate, compared to those from Laizhou bay. Moreover, the toxic effect of both HNS on net oxygenation rate and oxygen consumption rate were significantly attenuated as the concentration increased. The growth inhibition of microalgae cultured in two seawater samples was more evident at 0.5 and 5.0 mg L-1 p-chloroaniline than at 2.0 mg L-1 p-chloroaniline,and the growth inhibition of microalgae cultured in two seawater samples was more evident at 2.0 and 5.0 mg L-1 butyl acrylate than at 0.5 mg L-1 butyl acrylate. These results indicated that toxic effect of p-chloroaniline and butyl acrylate on the growth of N. oculata was influenced by the pollutants in the two water samples. Consequently, a corresponding research on water sample is required in advance to increase accuracy of future ecological risk assessment of HNS.

Plasma metabolomics of autism spectrum disorder and influence of shared components in proband families.

Prevalence of autism spectrum disorder (ASD) has been increasing in the United States in the past decades. The exact mechanisms remain enigmatic, and diagnosis of the disease still relies primarily on assessment of behavior. We first used a case-control design (75 idiopathic cases and 29 controls, enrolled at Boston Children's Hospital from 2007-2012) to identify plasma biomarkers of ASD through a metabolome-wide association study approach. Then we leveraged a family-based design (31 families) to investigate the influence of shared genetic and environmental components on the autism-associated features. Using untargeted high-resolution mass spectrometry metabolomics platforms, we detected 19 184 features. Of these, 191 were associated with ASD (false discovery rate < 0.05). We putatively annotated 30 features that had an odds ratio (OR) between <0.01 and 5.84. An identified endogenous metabolite, O-phosphotyrosine, was associated with an extremely low autism odds (OR 0.17; 95% confidence interval 0.06-0.39). We also found that glutathione metabolism was associated with ASD (P = 0.048). Correlations of the significant features between proband and parents were low (median = 0.09). Of the 30 annotated features, the median correlations within families (proband-parents) were -0.15 and 0.24 for the endogenous and exogenous metabolites, respectively. We hypothesize that, without feature identification, family-based correlation analysis of autism-associated features can be an alternative way to assist the prioritization of potentially diagnostic features. A panel of ASD diagnostic metabolic markers with high specificity could be derived upon further studies.

Environmental fate and aquatic effects of propylbenzenes and trimethylbenzenes: A review.

Propylbenzenes (PBZs) and trimethylbenzenes (TMBs) are aromatic hydrocarbon compounds widely used in many industries with potential release to different environments. The fate and aquatic effects of these compounds in the environment were evaluated. Evidence suggests that PBZs and TMBs will rapidly volatilise from water and bioaccumulate in aquatic organisms. Under both aerobic and anaerobic conditions, these compounds are readily biodegradable, whereby 1,2,3-TMB is more stable than the others. In air, all five compounds have atmospheric photo-oxidation half-lives ranging from 0.31 to 1.55 d. The toxicity data collectively show that PBZs, 1,2,4- and 1,3,5-TMB pose high acute toxicity effects on aquatic organisms. Furthermore, freshwater species are more sensitive to these compounds than marine species. There is not much data on the occurrence of PZBs and TMBs in the aquatic environment. This review presents the current state of knowledge on the fate of PBZs and TMBs. Moreover, the acute and joint toxicity of these compounds to different aquatic organisms, especially in marine organisms, warrants further investigation.

Migratory birds-one major source of environmental antibiotic resistance around Qinghai Lake, China.

Migratory birds are potential transmitters of bacterial antibiotic resistance. However, their role in the environmental dissemination of bacterial antibiotic resistance and the extent of their impact on the environment are not yet clear. Qinghai Lake is one of the most important breeding and stopover ground for the migratory birds along the Central Asian Flyway. Here, we investigated the bacterial antibiotic resistance in the environment and among the migratory birds around the lake. The results of culture-based analysis of bacterial antibiotic resistance, quantitative PCR and metagenomic sequencing indicate that migratory birds are one major source of bacterial antibiotic resistance in the environment around Qinghai Lake. Network analysis reveals the co-occurrence patterns of antibiotic resistance genes (ARGs) and bacterial genera. Genetic co-localization analysis suggests high co-selection potential (with incidence of 35.8%) among different ARGs, but limited linkage (with incidence of only 3.7%) between ARGs and biocide/metal resistance genes (BMRGs). The high genetic linkage between ARGs and mobile genetic elements (MGEs) is still largely confined to the bacterial community in migratory birds (accounting for 96.0% of sequencing reads of MGE-linked ARGs), which indicates limited horizontal transfer of ARGs to the environment. Nevertheless, the antibiotic resistance determinants carried by migratory birds and their specific genetic properties (high co-selection and mobility potential of the ARGs) remind us that the role of migratory birds in the environmental dissemination of bacterial antibiotic resistance deserves more attention.

The pathways by which the marine diatom Thalassiosira sp. OUC2 biodegrades p-xylene, combined with a mechanistic analysis at the proteomic level.

A marine diatom, Thalassiosira sp. OUC2, was isolated from natural seawater collected from Daya Bay, China. This diatom degraded 1.25-40 mg L-1p-xylene within five days, at a removal efficiency exceeding 98%. Gas chromatography-mass spectrometer (GC-MS) analysis indicated that p-xylene was converted into 4-methylbenzyl alcohol, p-toluic acid, and p-cresol in the presence of strain OUC2. Meanwhile, proteomic analysis showed that, after exposure to p-xylene, several algal enzymes were significantly upregulated: including monooxygenase, alcohol dehydrogenase, benzaldehyde dehydrogenase, benzoate 1,2-dioxygenase, and catechol 2,3-dioxygenase. Moreover, ecotoxicological tests suggested that the intermediate metabolites were less toxic than the parent compound (p-xylene). Thalassiosira sp. OUC2 may thus be suitable for the remediation of p-xylene-contaminated marine environments.

Metadata Analysis of mcr-1-Bearing Plasmids Inspired by the Sequencing Evidence for Horizontal Transfer of Antibiotic Resistance Genes Between Polluted River and Wild Birds.

We sequenced the whole genomes of three mcr-1-positive multidrug-resistant E. coli strains, which were previously isolated from the environment of egret habitat (polluted river) and egret feces. The results exhibit high correlation between antibiotic-resistant phenotype and genotype among the three strains. Most of the mobilized antibiotic resistance genes (ARGs) are distributed on plasmids in the forms of transposons or integrons. Multidrug-resistant (MDR) regions of high homology are detected on plasmids of different E. coli isolates. Therefore, horizontal transfer of resistance genes has facilitated the transmission of antibiotic resistance between the environmental and avian bacteria, and the transfer of ARGs have involved multiple embedded genetic levels (transposons, integrons, plasmids, and bacterial lineages). Inspired by this, systematic metadata analysis was performed for the available sequences of mcr-1-bearing plasmids. Among these plasmids, IncHI2 plasmids carry the most additional ARGs. The composition of these additional ARGs varies according to their geographical distribution. The phylogenetic reconstruction of IncI2 and IncX4 plasmids provides the evidence for their multiregional evolution. Phylogenetic analysis at the level of mobile genetic element (plasmid) provides important epidemiological information for the global dissemination of mcr-1 gene. Highly homologous mcr-1-bearing IncI2 plasmids have been isolated from different regions along the East Asian-Australasian Flyway, suggesting that migratory birds may mediate the intercontinental transportation of ARGs.