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Abstract Tetracycline antibiotics are the most widely used antibiotics in the world and the most common veterinary drugs and feed additives used in livestock, poultry and aquaculture operations. Because antibiotics cannot be completely removed by currently existing sewage treatment facilities, these materials enter the environment directly via sewage treatment plant discharge, where they degrade. Accordingly, the metabolism and the ecological toxicity of tetracycline degradation products are worthy of attention. Herein, we investigated the effects of tetracycline and its degradation products (anhydrotetracycline and epitetracycline hydrochloride) on the growth, cell structure and algal cell oxidative stress of common Chlorella vulgaris. The results showed that the 96h-EC 50 values of tetracycline (TC), anhydrotetracycline (ATC) and epitetracycline (ETC) on algal cells were 7.73, 5.96 and 8.42 mg/L, respectively. Moreover, the permeability of algal cells exposed to high concentrations of these three drugs was significantly enhanced. In addition, there were structural changes in the cells such as plasmolysis and starch granule deposition appeared, the thylakoid lamellae in the chloroplasts became blurred and deformed, and the vacuoles became larger. Exposure to higher concentrations (>5 mg/L) of TC and its degradation products ATC and ETC significantly upregulated the activity of ROS, as well as the antioxidants SOD and CAT. The levels of the lipid peroxidation product MDA also showed the same trend. Finally, ATC had the strongest toxicity toward algal cells, followed by TC and then ETC. Highlights • We investigated the toxic effects of TC and its degradation products on green algae. • Toxic effects were discussed through the ultrastructure observation of algal cells. • ATC had the strongest toxicity toward algal cells. [ABSTRACT FROM AUTHOR]

Toll-like receptor 2 (TLR2) has been shown to play a crucial role in the host defense of pathogenic microbes in innate immunity. In this study, the full-length cDNA of TLR2 in silvery pomfret ( Pampus argenteus ) was cloned by homology cloning and the rapid amplification of cDNA ends (RACE) technique. The complete cDNA sequence of TLR2 was 2932 bp, containing an open reading frame (ORF) of 2469 bp encoding 822 amino acids. A multiple alignment analysis of the silvery pomfret TLR2 protein-coding sequence with other known TLR2 sequences from Oplegnathus fasciatus , Epinephelus coioides , Larimichthys crocea , Miichthys miiuy , Oreochromis niloticus , Paralichthys olivaceus , Trematomus bernacchii , Sparus aurata, and Chionodraco hamatus exhibited a high degree of homology of 78.83%, 75.91%, 74.21%, 74.94%, 71.95%, 72.57%, 73.68%, 75%, and 72.52 respectively, between these fish. Analysis of the TLR2 domain structures indicated that TLR2 from the silvery pomfret has the typical structural features of proteins that belong to the TLR family, including one transmembrane domain, eleven leucine-rich repeats (LRRs), and one Toll/IL-1 receptor homology domain (TIR). In vitro immunostimulation experiments revealed that Lactobacillus plantarum and Clostridium butyricum induce high levels of TLR2 mRNA and protein expression, but they induce only moderate levels of IL-8 and TNF-α production compared to Vibrio anguillarum . This suggests that TLR2 might play a vital role in the L. plantarum and C. butyricum -mediated immune response. In contrast, V. anguillarum significantly increased the secretion of IL-8 and TNF-α and induced cell apoptosis and necrosis. Due to the lower expression of TLR2 and higher levels of IL-8 and TNF-α induced by V. anguillarum , we hypothesize that a V. anguillarum infection is independent of the TLR2-induced production of pro-inflammatory cytokines. These results indicate that TLR2 may be involved in molecular interactions between the host and commensal bacteria, that exist in the silvery pomfret intestinal tract. [ABSTRACT FROM AUTHOR]

Photocatalysis degradation of tetracycline hydrochloride with high concentration over a hollow microsphere S-doped g-C 3 N 4. [Display omitted] For the past few years, graphitic carbon nitride (g-C 3 N 4) has been widely used to eliminate environmental pollutants, but limited active site on surface and low separation/migration ability suppress its practical uses. Herein, we adopted a supramolecular self-assembly route followed with S doping to synthesize S-doped g-C 3 N 4 with a hollow microsphere composition (SCNHM), where the shell was demonstrated to compose of ultrathin nanosheets. The unique structural characteristics endow the SCNHM with high specific surface area (∼81 m2 g−1) to provide abundant reaction sites and enhanced light-harvesting due to the light-scattering effect of hollow structure. Moreover, the S dopant meliorated the electronic structure to narrow the bandgap and promoted the charge separation/transfer capability. With this synergistic effect, the SCNHM presented greatly improved photocatalytic activity for degrading tetracycline hydrochloride (TC) compared to the CN, SCN and CNHM samples. This photocatalyst could eliminate high-concentration TC (50 mg L−1) in 18 min, and the 30 min removal efficiencies of 100 mg L−1 and 200 mg L−1 reached 92 % and 60 %, which is much better than the reported photocatalysts in literatures (usually ≤ 20 mg L−1). Additionally, the good photocatalytic durability was confirmed and the degradation pathway of TC was proposed. Furthermore, the SCNHM was proved to meanwhile possess superior performance for inactivating the typical Gram-positive bacterium of Staphylococcus aureus (S. aureus) and the typical Gram-negative bacterium of Escherichia coli (E. coli). Finally, based on determination of band alignment and detection of active species, a plausible photocatalytic mechanism was proposed. [ABSTRACT FROM AUTHOR]

Visible-light-driven photocatalytic degradation of moxifloxacin over a aminobenzaldehyde grafted graphitic carbon nitride. [Display omitted] Graphitic carbon nitride (GCN) has been demonstrated to be a potential visible-light-driven photocatalyst for eliminating organic pollutants. However, its practical application is limited by low photocatalytic efficiency originating from high recombination of photogenerated charges. In this work, the electronic structure of GCN was regulated by doping aminobenzaldehyde (ABA) into the skeleton through a solid-state Schiff base reaction. Photoelectrochemical characterizations illustrated that the obtained catalyst (CNABA) exhibited narrower band gap, lower recombination rate of photoinduced electron-hole pair and higher charge transfer ability than the pristine GCN, further indicating its excellent photocatalytic activity. Using moxifloxacin (MOX) as a model pollutant, the ABA doping content was firstly optimized and the optimal activity of the CNABA photocatalyst was 3.1 times higher than that of the GCN. Subsequently, the effects of pH value, photocatalyst dosage and MOX concentration on the photocatalytic behavior were also studied. Superior stability and photocatalytic reusability were confirmed by five repeated tests. By substituting tap water/natural lake water for deionized water and sunlight for xenon light, the CNABA also exhibited high elimination efficiency, implying its good practicability. Superoxide radical, hydroxyl radical and photogenerated hole were identified as the main active species to degrade MOX. Finally, possible degradation pathways for MOX to mineralize small molecules were proposed by determining intermediate products during photocatalysis. This work provides a solid-state method to rationally design aromatic system-modified GCN photocatalysts, and the obtained CNABA is a promising visible-light-driven photocatalyst for eliminating antibiotics. [ABSTRACT FROM AUTHOR]

We compared viability, morphology, enzyme activity and gene expression patterns between the chlorine tolerant S. Enteritidis RE 13 and the sensitive strain S. Enteritidis CVCC1806. As expected, viability of strain CVCC1806 was significantly lower than for RE 13 after exposure to 100 mg/L NaClO for 20 min and the sensitive strain displayed severe cell membrane damage and intracellular ATP depletion compared with the tolerant strain. The NAD+/NADH ratios for the sensitive vs tolerant strain were also significantly (p < 0.05) different (3.59 ± 0.95 vs. 0.88 ± 0.47) and indicated that tolerance included adaptation to redox perturbations. Transcriptomes of these two strains following chlorine exposure identified significant up-regulation of efflux pump systems (proV/W , OmpF , marA), oxidative stress response (trxC, yhhP, soxS) and DNA repair (dnaQ , polB , yaiV) for the tolerant RE 13 strain. These data indicated that S. Enteritidis RE 13 has a more robust response to oxidative stress that acted to maintain its intracellular redox balance to adapt and survive in the presence of chlorine. Noteworthy, the operon gene cluster of the bacterial microcompartment PDU were up-regulated about 64-fold in tolerant strain RE 13 compared with the sensitive strain, posing a more serious threat to human intestinal health. • The tolerant strain kept viability and membrane integrity under chlorine stress. • Transcriptome response between chlorine tolerant and sensitive strain was compared. • Multiple efflux pumps were triggered by NaClO, leading to chlorine resistance. • Pdu operon was upregulated in tolerant strain that may be more pathogenic. [ABSTRACT FROM AUTHOR]