Synergy between Nitrogen Removal and Fermentation Bacteria Ensured Efficient Nitrogen Removal of a Mainstream Anammox System at Low Temperatures.

Simultaneous partial nitrification, anammox, denitrification, and fermentation (SNADF) is a novel process achieving simultaneous advanced sludge reduction and nitrogen removal. The influence of low temperatures on the SNADF reactor was explored to facilitate the application of mainstream anammox. When temperature decreased from 32 to 16 °C, efficient nitrogen removal was achieved, with a nitrogen removal efficiency of 81.9-94.9%. Microbial community structure analysis indicated that the abundance of Candidatus Brocadia (dominant anaerobic ammonia oxidizing bacteria (AnAOB) in the system) increased from 0.03% to 0.18%. The abundances of Nitrospira and Nitrosomonas increased from 1.6% and 0.16% to 2.5% and 1.63%, respectively, resulting in an increase in the ammonia-oxidizing bacteria (AOB) to nitrite-oxidizing bacteria (NOB) abundance ratio from 0.1 to 0.64. This ensured sufficient nitrite for AnAOB, promoting nitrogen removal. In addition, Candidatus Competibacter, which plays a role in partial denitrification, was the dominant denitrification bacteria (DNB) and provided more nitrite for AnAOB, facilitating AnAOB enrichment. Based on the findings from microbial correlation network analysis, Nitrosomonas (AOB), Thauera, and Haliangium (DNB), and A4b and Saprospiraceae (fermentation bacteria), were center nodes in the networks and therefore essential for the stability of the SNADF system. Moreover, fermentation bacteria, DNB, and AOB had close connections in substrate cooperation and resistance to adverse environments; therefore, they also played important roles in maintaining stable nitrogen removal at low temperatures. This study provided new suggestions for mainstream anammox application.

Sludge-derived alginate-like extracellular polymers (ALE) for preparation of Fe-ALE and FeCaMg-ALE: Application to the adsorption of phosphate.

Excess phosphorus (P) in wastewater has potential risk of causing harmful algal bloom and eutrophication in receiving wastewater. In this study, alginate-like extracellular polymers (ALE) derived from conventional activated sludge were modified with ionic cross-linking agents (Fe3+, Ca2+, and Mg2+) to develop Fe-ALE and FeCaMg-ALE for the adsorption of phosphate from wastewater. The adsorption process of phosphate by Fe-ALE and FeCaMg-ALE can be well described by pseudo-second-order kinetics and Freundlich isotherm model with a high level of accuracy, indicating that the adsorption processes were chemical, multi-layer adsorption process. The maximum adsorption capacity of dry Fe-ALE and FeCaMg-ALE concerning phosphate were 15.06 and 20.10 mg/g, respectively at 298 K. The adsorption capacity remained relatively consistent across a pH range of 2.0-11.0. FT-IR, XRD, SEM coupled with XPS analysis demonstrated the ALE had been successfully compounded with Fe3+ or Fe3+/Ca2+/Mg2+. Based on the experimental results and characteristic analysis, the main mechanism of phosphate by Fe-ALE and FeCaMg-ALE are physical filling, electrostatic attraction, ligand exchange and precipitation reaction. This work provides a new perspective for preparing ALE-based adsorbent using conventional activated sludge as raw material, realizing the treatment of waste with waste and effectively recovering phosphate from wastewater.

Quorum Quenching in Membrane Bioreactors for Fouling Retardation: Complexity Provides Opportunities.

The occurrence of biofouling restricts the widespread application of membrane bioreactors (MBRs) in wastewater treatment. Regulation of quorum sensing (QS) is a promising approach to control biofouling in MBRs, yet the underlying mechanisms are complex and remain to be illustrated. A fundamental understanding of the relationship between QS and membrane biofouling in MBRs is lacking, which hampers the development and application of quorum quenching (QQ) techniques in MBRs (QQMBRs). While many QQ microorganisms have been isolated thus far, critical criteria for selecting desirable QQ microorganisms are still missing. Furthermore, there are inconsistent results regarding the QQ lifecycle and the effects of QQ on the physicochemical characteristics and microbial communities of the mixed liquor and biofouling assemblages in QQMBRs, which might result in unreliable and inefficient QQ applications. This review aims to comprehensively summarize timely QQ research and highlight the important yet often ignored perspectives of QQ for biofouling control in MBRs. We consider what this "information" can and cannot tell us and explore its values in addressing specific and important questions in QQMBRs. Herein, we first examine current analytical methods of QS signals and discuss the critical roles of QS in fouling-forming microorganisms in MBRs, which are the cornerstones for the development of QQ technologies. To achieve targeting QQ strategies in MBRs, we propose the substrate specificity and degradation capability of isolated QQ microorganisms and the surface area and pore structures of QQ media as the critical criteria to select desirable functional microbes and media, respectively. To validate the biofouling retardation efficiency, we further specify the QQ effects on the physicochemical properties, microbial community composition, and succession of mixed liquor and biofouling assemblages in MBRs. Finally, we provide scale-up considerations of QQMBRs in terms of the debated QQ lifecycle, practical synergistic strategies, and the potential cost savings of MBRs. This review presents the limitations of classic QS/QQ hypotheses in MBRs, advances the understanding of the role of QS/QQ in biofouling development/retardation in MBRs, and builds a bridge between the fundamental understandings and practical applications of QQ technology.

Effects of environmentally relevant concentrations of florfenicol on the glucose metabolism system, intestinal microbiome, and liver metabolome of zebrafish.

Florfenicol, a widely used veterinary antibiotic, has now been frequently detected in various water environments and human urines, with high concentrations. Accordingly, the ecological risks and health hazards of florfenicol are attracting increasing attention. In recent years, antibiotic exposure has been implicated in the disruption of animal glucose metabolism. However, the specific effects of florfenicol on the glucose metabolism system and the underlying mechanisms are largely unknown. Herein, zebrafish as an animal model were exposed to environmentally relevant concentrations of florfenicol for 28 days. Using biochemical and molecular analyses, we found that exposure to florfenicol disturbed glucose homeostasis, as evidenced by the abnormal levels of blood glucose and hepatic/muscular glycogen, and the altered expression of genes involved in glycogenolysis, gluconeogenesis, glycogenesis, and glycolysis. Considering the efficient antibacterial activity of florfenicol and the crucial role of intestinal flora in host glucose metabolism, we then analyzed changes in the gut microbiome and its key metabolite short-chain fatty acids (SCFAs). Results indicated that exposure to florfenicol caused gut microbiota dysbiosis, inhibited the production of intestinal SCFAs, and ultimately affected the downstream signaling pathways of SCFA involved in glucose metabolism. Moreover, non-targeted metabolomics revealed that arachidonic acid and linoleic acid metabolic pathways may be associated with insulin sensitivity changes in florfenicol-exposed livers. Overall, this study highlighted a crucial aspect of the environmental risks of florfenicol to both non-target organisms and humans, and presented novel insights into the mechanistic elucidation of metabolic toxicity of antibiotics.

Characterization of the Nucleus Pulposus Progenitor Cells via Spatial Transcriptomics.

Loss of refreshment in nucleus pulposus (NP) cellularity leads to intervertebral disc (IVD) degeneration. Nevertheless, the cellular sequence of NP cell differentiation remains unclear, although an increasing body of literature has identified markers of NP progenitor cells (NPPCs). Notably, due to their fragility, the physical enrichment of NP-derived cells has limited conventional transcriptomic approaches in multiple studies. To overcome this limitation, a spatially resolved transcriptional atlas of the mouse IVD is generated via the 10x Genomics Visium platform dividing NP spots into two clusters. Based on this, most reported NPPC-markers, including Cathepsin K (Ctsk), are rare and predominantly located within the NP-outer subset. Cell lineage tracing further evidence that a small number of Ctsk-expressing cells generate the entire adult NP tissue. In contrast, Tie2, which has long suggested labeling NPPCs, is actually neither expressed in NP subsets nor labels NPPCs and their descendants in mouse models; consistent with this, an in situ sequencing (ISS) analysis validated the absence of Tie2 in NP tissue. Similarly, no Tie2-cre-mediated labeling of NPPCs is observed in an IVD degenerative mouse model. Altogether, in this study, the first spatial transcriptomic map of the IVD is established, thereby providing a public resource for bone biology.

Biotoxicity dynamic change and key toxic organics identification of coal chemical wastewater along a novel full-scale treatment process.

It is particularly important to comprehensively assess the biotoxicity variation of industrial wastewater along the treatment process for ensuring the water environment security. However, intensive studies on the biotoxicity reduction of industrial wastewater are still limited. In this study, the toxic organics removal and biotoxicity reduction of coal chemical wastewater (CCW) along a novel full-scale treatment process based on the pretreatment process-anaerobic process-biological enhanced (BE) process-anoxic/oxic (A/O) process-advanced treatment process was evaluated. This process performed great removal efficiency of COD, total phenol, NH4+-N and total nitrogen. And the biotoxicity variation along the treatment units was analyzed from the perspective of acute biotoxicity, genotixicity and oxidative damage. The results indicated that the effluent of pretreatment process presented relatively high acute biotoxicity to Tetrahymena thermophila. But the acute biotoxicity was significantly reduced in BE-A/O process. And the genotoxicity and oxidative damage to Tetrahymena thermophila were significantly decreased after advanced treatment. The polar organics in CCW were identified as the main biotoxicity contributors. Phenols were positively correlated with acute biotoxicity, while the nitrogenous heterocyclic compounds and polycyclic aromatic hydrocarbons were positively correlated with genotoxicity. Although the biotoxicity was effectively reduced in the novel full-scale treatment process, the effluent still performed potential biotoxicity, which need to be further explored in order to reduce environmental risk.

Development, Validation and Characterization of a Novel Portable Closed Fracture Device.

BACKGROUND/AIM: As one of the common clinical diseases, fractures have many causes, mechanisms, healing and influencing factors; especially fracture healing is a long-term and complex process. Animal fracture models can simulate the various states of human fractures, and on this basis, the prevention, mechanism, and treatment of fractures can be studied to further guide clinical practice. MATERIALS AND METHODS: Here, we developed a novel and portable device to create a closed fracture model in mice. We then compared this novel closed fracture model with the traditional open model in multiple dimensions to evaluate the modelling process of establishment and healing. The two models were evaluated by imaging, immunostaining, and behavioral tests, which fully demonstrated the stability, universality and operability of the modified fracture model in mice. RESULTS: Surgical quality assessment revealed that the closed fracture model had a shorter operation time and smaller wound than the open model. X-ray and micro-CT results showed no differences between the two models in the evaluation of radiographic and morphological changes during fracture healing. Histological examination revealed the process of the typical intrachondral osteogenic pathway after fracture. Moreover, animal gait analysis indicated reduced postoperative pain in the closed group compared to the open group. CONCLUSION: This study provides a constructive strategy for a closed fracture model in mice and demonstrates the effectiveness and feasibility of the closed fracture model in studying the typical intrachondral osteogenic pathway of fractures from multiple dimensions.

Novel strategy to enhance the biological treatment of coal chemical wastewater by nano-zero valent iron loaded fly ash-based activated carbon assisted activated sludge process.

Industrial waste as novel conductive mediator was applied for wastewater treatment as a novel strategy for both waste recycling and sustainable development of wastewater treatment. In this study, nanoscale zero valent iron-loaded fly ash-based activated carbon (nZVI@FABAC) was prepared and applied to enhancing activated sludge (AS) process for coal chemical wastewater (CCW) treatment. The results demonstrated that the removal efficiencies of COD and total phenols (TPh) in nZVI@FABAC/AS process reached about 83.96 and 85.17%, which increased 52.51 and 31.52% compared with the single AS process, respectively. And the acute toxic unit value of CCW was reduced by 88.24% after nZVI@FABAC/AS process treatment. The various functional bacteria including phenol-degrading bacteria (Comamonas and Acinetobacter), electroactive bacteria (Geobacter), and iron reduction bacteria (Geothrix) were enriched in the nZVI@FABAC/AS process, which provided various electron transfer pathways to improve the degradation of toxic organics in CCW. Accordingly, nZVI@FABAC/AS process provided a promising and sustainable way for industrial wastewater treatment.

Extracts of Dunkelfelder Grape Seeds and Peel Increase the Metabolic Rate and Reduce Fat Deposition in Mice Maintained on a High-Fat Diet.

Chronic high-fat diet intake may induce obesity and increase the risk of metabolic syndrome. The pomace of grape (Vitis vinifera L.) is rich in polyphenols, which are candidates for anti-obesity therapy. The present study aimed to investigate the effects of Dunkelfelder grape seed extract (GSE) and grape peel extract (GPE) on lipid and energy metabolism disorders in mice maintained on a high-fat diet (HFD). Male nine-week C57BL/6J mice were randomly assigned to one of four groups, namely, the normal chow diet (ND), HFD, HFD plus GSE (400 mg/kg BW) administered by oral gavage, or HFD plus GPE (400 mg/kg BW) administered by oral gavage. There were eight mice per group, and the experiment was 14 weeks in duration. The results showed that GSE and GPE treatments did not affect energy intake in mice on a high-fat diet, but body weight gain was 24.5% and 17.3% lower in the GSE- and GPE-treated mice than in the HFD group, respectively. They also decreased blood triglyceride (TG), total cholesterol (TC), and fasting blood glucose levels and increased high-density lipoprotein cholesterol (HDL-C). In addition, GSE and GPE reduced adipose tissue weight and excessive lipid droplet accumulation in the adipocytes. The metabolic chamber test showed that the GSE and GPE treatments enhanced oxygen consumption, carbon dioxide production, and heat release while decreasing the respiratory exchange rate (RER). This suggests that GSE and GPE augmented fuel oxidation and energy generation and increased the proportion of lipids being utilized in energy metabolism. GSE and GPE also upregulated the genes controlling lipolysis and downregulated those controlling lipogenesis in adipose tissues. Moreover, they significantly increased the expression levels of the genes regulating thermogenesis in BAT, eWAT, and iWAT, and mitochondrial biogenesis in all three types of adipose tissue. In conclusion, the present study empirically demonstrated that GSE and GPE enhance body fat utilization by augmenting lipid and energy metabolism and could, therefore, ameliorate high-fat diet-induced obesity.

Establishment and evaluation of a modified mouse model of renal subcapsular transplantation of microvolume cells.

The renal subcapsular space provides an easily accessible, nutrition-rich pocket that supports engraftment, and as such, is often used as a site for stem and cancer cell transplantation. Renal capsule transplantation requires high technical requirements, the recipient mice have greater surgical damage, the mouse kidney is small and the kidney capsule is fragile, and the operation is easy to fail. The conventional method is not suitable for microvolume cell transplantation to this site in animals with a small kidney, such as mice, due to high risks of cell loss or dislocation or injury to the capsule. In this study, we developed and validated a modified approach for the mouse model of renal subcapsular transplantation of microvolume mouse skeletal stem cells (SSCs). We used a pipette with a refined tip to separate the capsule from the parenchyma. Moreover, we used cells suspended in Matrigel rather than a liquid carrier for transplantation. Using the modified method, we were able to transplant microvolume mouse SSCs as low as 0.2 µL beneath the mouse renal capsule with excellent reproducibility. After 4 weeks of in vivo culture, the implanted mouse SSCs formed grafts on the surface of the parenchyma at the target site of transplantation. Histological staining of the grafts indicated osteogenic, fibrogenic, and lipogenic differentiation. Micro-CT imaging of the grafts revealed bone formation. This modified model could be used to effectively transplant different types of microvolume cells to the renal subcapsular space when the donor cells are difficult to acquire or the recipient mice have a very small size kidney.

Pollutants removal and connections among sludge properties, metabolism potential and microbial characteristics in aerobic granular sequencing batch reactor for petrochemical wastewater treatment.

Petrochemical wastewater contains inhibitory compounds such as aromatics that are toxic to microorganisms during biological treatment. The compact and layered structure and the high amount of extracellular polymeric substances (EPS) in aerobic granular sludge (AGS) can contribute to protecting microorganisms from the harsh environment. This study evaluated the changes in the granule properties, pollutants removal, microbial metabolic potential and molecular microbial characteristics of the AGS process for petrochemical wastewater treatment. Granules treating petrochemical wastewater had a higher SVI30/SVI5 value (0.94) than that treating synthetic wastewater. An increase in bioactivity and EPS secretion with higher bio-polymer composition, specifically the functional groups such as hydroxyl, alkoxy and amino in protein, was observed, which promoted biomass aggregation. The granules also had more than 2-fold higher specific oxygen utilization rate. The AGS-SBR process obtained an average COD removal of 93% during petrochemical wastewater treatment and an effluent bCOD of below 1 mg L-1. No obvious inhibition of nitrification and denitrification activity was observed in the processes attributed to the layered structure of AGS. The average effluent NH4+-N of 5.0 mg L-1 was obtained and TN removal efficiencies of over 80.0% was achieved. Molecular microbial analysis showed that abundant functional genera Stenotrophomonas and Pseudoxanthomonas contributed to the degradation of aromatics and other petroleum organic pollutants. They were enriched with the variation of group behavior while metabolisms of amino acids and carboxylic acids by the relevant functional genera (e.g., Cytophagia) were significantly inhibited. The enrichment of Flavobacterium and Thermomonas promoted nitrification and denitrification, respectively. This research revealed the rapid start-up, enhanced granule structural strength, high inhibition resistance and considerable performance of AGS-SBR for petrochemical wastewater treatment.

Lead-imprinted polyvinylidene fluoride membrane for selective removal of lead from contaminated water: material fabrication, filtration application, and mechanism study.

The drinking water has become contaminated with lead in many countries across the world. In this study, a novel lead-imprinted polyvinylidene fluoride (PVDF) membrane was successfully fabricated for selective decontamination of lead from water. First of all, the membrane fabrication process was explored and optimized. The physical and chemical properties were then studied for a better understanding of the features of the membrane. The performance of lead removal by the adsorptive membrane was evaluated by systematic batch adsorption experiments, including pH effect, kinetics, isotherm, selectivity, and regeneration studies. The results indicated that the adsorptive membrane showed a high adsorption capacity of 40.59 mg Pb/g at the optimal pH of 5.5, fast kinetics of 2 h, high selectivity towards lead, and outstanding regeneration performance. The Langmuir equation fitted the isotherm better than the Freundlich equation, while the pseudo-second-order model and pore diffusion model well described the kinetics. The adsorptive membrane showed high selectivity towards lead in the lead/zinc binary solution. In the continuous filtration study, a small piece of adsorptive membrane could treat 3.75 L of lead solution. The XPS studies revealed that the lead uptake was mainly due to the complex reaction between lead and carboxyl and hydroxyl in the membrane.

NiCo bimetallic and the corresponding monometallic organic frameworks loaded CMC aerogels for adsorbing Cu2+: Adsorption behavior and mechanism.

In this study, three-dimensional (3D) carboxymethylcellulose sodium (CMC) aerogel was decorated with NiCo bimetallic and the corresponding monometallic organic frameworks to prepare MOFs-CMC composite adsorbents for the removal of Cu2+. The obtained MOFs-CMC composite including Ni/Co-MOF-CMC, Ni-MOF-CMC, and Co-MOF-CMC were characterized by SEM, FT-IR, XRD, XPS analysis, and zeta potential. The adsorption behavior of MOFs-CMC composite for Cu2+ was explored by batch adsorption test, adsorption kinetics and adsorption isotherms. The experimental data satisfied the pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacities followed the sequence of Ni/Co-MOF-CMC (233.99 mg/g) > Ni-MOF-CMC (216.95 mg/g) > Co-MOF-CMC (214.38 mg/g), indicating that there was a synergistic effect between Ni and Co to promote the adsorption of Cu2+. Combining characterization analysis and density functional theory (DFT) calculation, it is clarified that the adsorption mechanism of MOFs-CMC for Cu2+ includes ion exchange, electrostatic interactions, and complexation.

Safety assessment of organic micropollutants in reclaimed water: Chemical analyses, ecological risk assessments, and in vivo endocrine-disrupting studies.

Reclaimed water from municipal wastewater has great potential in mitigating the water resource crisis, while the inevitable residue of organic micropollutants (OMPs) challenges the safety of reclaimed water reuse. Limited information was available regarding the overall adverse effects of mixed OMPs in reclaimed water, especially the endocrine-disrupting effects on living organisms. Herein, chemical monitoring in two municipal wastewater treatment plants showed that 31 of 32 candidate OMPs including polycyclic aromatic hydrocarbons (PAHs), phenols, pharmaceuticals and personal care products (PPCPs) were detected in reclaimed water, with a concentration ranging from ng/L to µg/L. Then, based on the risk quotient value, phenol, bisphenol A, tetracycline, and carbamazepine were ranked as high ecological risks. Most PAHs and PPCPs were quantified as medium and low risks, respectively. More importantly, using aquatic vertebrate zebrafish as an in vivo model, the endocrine-disrupting potentials of OMP mixtures were comprehensively characterized. We found that a realistic exposure to reclaimed water induced estrogen-like endocrine disruption and hyperthyroidism in zebrafish, abnormal expression of genes along the hypothalamus-pituitary-thyroid (-gonad) axes, reproductive impairment, and transgenerational toxicity. Based on the chemical analyses, risk quotient calculations, and biotoxicity characterization, this study contributed to understanding the ecological risks of reclaimed water and developing the control standards for OMPs. In addition, application of the zebrafish model in this study also highlighted the significance of in vivo biotoxicity test in water quality evaluation.

Novel Y2O3 based calcium-alginate beads for highly selective adsorption of phosphate from aqueous solution.

Recently, selective phosphorus removal from aqueous solution has been a highly desirable strategy to combat eutrophication due to the increasingly stringent phosphorous emission standards. However, conventional adsorbents pose the limitations in phosphate removal suffering from lack of selectivity and stability under complicated condition and poor separation. In this study, novel Y2O3 based calcium-alginate (Y2O3/SA) beads of feasible stability and highly selectivity towards phosphate by encapsulating Y2O3 nanoparticles inside calcium-alginate beads via Ca2+ controlled gelation process was synthesized and characterized. The phosphate adsorption performance and mechanism were investigated. In general, a high selectivity among co-existing anions was found with co-existing anion concentration up to 62.5 times of the phosphate concentration. Additionally, phosphate adsorption by Y2O3/SA beads exhibited stable performance over a wide pH range between 2 and 10, while reaching the maximum adsorption capacity at pH 3 (48.54 mg-P/g). The value of point of zero charge (pHpzc) of Y2O3/SA beads was approximately 3.45. Pseudo-second-order and Freundlich isotherm models can well accord with kinetics and isotherms data. The FTIR and XPS characterizations analyzed that inner-sphere complexes were proposed to be the major contributor of Y2O3/SA beads for phosphate removal. In conclusion, Y2O3/SA beads as the mesoporous material exhibited excellent stability and selectivity towards phosphate removal.

Upflow anaerobic sludge blanket reactor operation under high pressure for energy-rich biogas production.

Autogenerative high-pressure digestion has an advantage of producing CH4-rich biogas directly from the reactor. However, its continuous operation has rarely been reported, and has never been attempted in an upflow anaerobic sludge blanket reactor (UASB). Here, UASB was continuously operated at 10 g COD/L/d with increasing pressure from 1 to 8 bar. As the pressure increased, the CH4 content in the biogas increased gradually, reaching 96.7 ± 0.8% at 8 bar (309 MJ/m3 biogas). The pH was dropped from 8.2 to 7.2 with pressure increase, but COD removal efficiency was maintained > 90%. The high pressure up to 8 bar did not adversely impact the physicochemical properties of granules, which was due to the increased production of extracellular polymeric substances (EPS), particularly, tightly bound EPS (34% increase). With pressure increase, there was no changes in the microbial community and ATPase gene expression, but 41% increase in carbonic anhydrase gene expression was observed.

Functional graphene oxide for organic pollutants removal from wastewater: a mini review.

Graphene oxide (GO), an important derivative of graphene, with a variety of active oxygen-containing groups (hydroxyl, carboxyl and epoxy) on its surface is easy to be functionalized to obtain adsorbent with high adsorption capacity. To date, the adsorption behaviour of organic pollutants by functionalized GO adsorbents have been extensively studied, but there has been no systematic review regarding the functionalization method of GO for the purpose to remove organic pollutants from wastewater. The leading objective of this review is to (i) summarize the functionalization strategies of GO for organic pollutants removal (covalent functionalization and non-covalent functionalization), (ii) evaluate the adsorption performance of functional GO towards organic pollutants by taking aromatic pollutants and dyes as examples and (iii) discuss the regeneration property and adsorption mechanism of functional GO adsorbent. In addition, the problems of existing studies and future research directions are also identified briefly.

Vascular anatomy-based localization of intervertebral discs assisting needle puncture for constructing a mouse model of mechanical injury-induced lumbar intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) may be the primary cause of low back pain. Potential therapeutics for IDD must be validated in animal models, and their effectiveness quantified using functional metrics. Needle puncture of intervertebral discs (IVDs) has been used to induce IDD in mice and rats. Due to operational challenges, most animal IDD models are constructed using needle puncture of the caudal IVDs in mice, or by using larger animals, such as rats and rabbits. However, mouse IDD models involving lumbar IVD puncture are preferable because mice are genetically similar to humans and are the most commonly used transgenic animals, and because human IDD commonly affects the lumbar spine. We constructed a needle puncture-based mouse IDD model that relies on vascular anatomy to pinpoint lumbar IVDs. We evaluated the morphological and molecular changes in this model by using radiological, pathological, and immunostaining examinations. In our mechanical injury-induced IDD model, lumbar IVDs were accurately localized by injecting colored perfusates into the common iliac artery and vein, and right iliolumbar vein, which helped to visualize puncture positions, avoid neuromuscular injury, shorten the operation time, and decrease bleeding. Nucleus pulposus cells, defined by Krt19, and the disc height index gradually decreased after the surgery, and the degenerative effects peaked at 1 week. In conclusion, we established a mouse IDD model by performing precise puncture of lumbar IVDs via the ventral anterior approach assisted by vessel position. Our model effectively simulated the effects of IDD, and may serve as an efficient research tool.

Early- and whole-life exposures to florfenicol disrupts lipid metabolism and induces obesogenic effects in zebrafish (Danio rerio).

Florfenicol (FF), a widely used veterinary antibiotic, has been frequently detected in both aquatic environments and human body fluids. As a result, there is a growing concern on its health risks. Previous studies have revealed various toxicities of FF on animals, while there are relatively limited researches on its metabolic toxicity. Herein, by employing zebrafish as an in vivo model, endpoints at multiple levels of biological organization were measured to investigate the metabolic toxicity, especially disturbances on lipid metabolism, of this emerging pollutant. Our results indicated that early-life exposure (from 2 h past fertilization (hpf) to 15 days past fertilization (dpf)) to FF significantly increased body mass index (BMI) values, staining areas of visceral lipids, and triacylglycerol (TAG) and total cholesterol (TC) contents of larvae. Further, by analyzing expression patterns of genes encoding key proteins regulating lipid metabolism, our data suggested that promoted intestinal absorption and hepatic de novo synthesis of lipids, suppressed TAG decomposition, and inhibited FFA oxidation all contributed to TAG accumulation in larvae. Following whole-life exposure (from 2 hpf to 120 dpf), BMI values, TAG and TC contents all increased significantly in males, and significant increases of hepatic TAG levels were also observed in females. Moreover, FF exposure interfered with lipid homeostasis of males and females in a gender-specific pattern. Our study revealed the obesogenic effects of FF at environmentally relevant concentrations (1, 10, and 100 µg/L) and therefore will benefit assessment of its health risks. Additionally, our results showed that FF exposure caused a more pronounced obesogenic effect in zebrafish larvae than adults, as suggested by significant increases of all endpoints at individual, tissular, and molecular levels in larvae. Therefore, our study also advances the application of zebrafish larval model in assessing metabolic toxicity of chemicals, due to the higher susceptibility of larvae than adults.

Metagenomic insights into microbial nitrogen metabolism in two-stage anoxic/oxic-moving bed biofilm reactor system with multiple chambers for municipal wastewater treatment.

To explore the microbial nitrogen metabolism of a two-stage anoxic/oxic (A/O)-moving bed biofilm reactor (MBBR), biofilms of the system's chambers were analyzed using metagenomic sequencing. Significant differences in microbial populations were found among the pre-anoxic, oxic and post-anoxic MBBRs (P < 0.01). Nitrospira and Nitrosomonas had positive correlations with ammonia nitrogen (NH4+-N) removal, and were also predominant in oxic MBBRs. These organisms were the hosts of functional genes for nitrification. The denitrifying genera were predominant in anoxic MBBRs, including Thiobacillus and Sulfurisoma in pre-anoxic MBBRs and Dechloromonas and Thauera in post-anoxic MBBRs. The four genera had positive correlations with total nitrate and nitrite nitrogen (NOX--N) removal and were the hosts of functional genes for denitrification. Specific functional biofilms with different microbial nitrogen metabolisms were formed in each chamber of this system. This work provides a microbial theoretical support for the two-stage A/O-MBBR system.