Intramuscular therapeutic doses of enrofloxacin affect microbial community structure but not the relative abundance of fluoroquinolones resistance genes in swine manure.

Livestock manure is a major source of veterinary antibiotics and antibiotic resistance genes (ARGs). Elucidation of the residual characteristics of ARGs in livestock manure following the administration of veterinary antibiotics is critical to assess their ecotoxicological effects and environmental contamination risks. Here, we investigated the effects of enrofloxacin (ENR), a fluoroquinolone antibiotic commonly used as a therapeutic drug in animal husbandry, on the characteristics of ARGs, mobile genetic elements, and microbial community structure in swine manure following its intramuscular administration for 3 days and a withdrawal period of 10 days. The results revealed the highest concentrations of ENR and ciprofloxacin (CIP) in swine manure at the end of the administration period, ENR concentrations in swine manure in groups L and H were 88.67 ± 45.46 and 219.75 ± 88.05 mg/kg DM, respectively. Approximately 15 fluoroquinolone resistance genes (FRGs) and 48 fluoroquinolone-related multidrug resistance genes (F-MRGs) were detected in swine manure; the relative abundance of the F-MRGs was considerably higher than that of the FRGs. On day 3, the relative abundance of qacA was significantly higher in group H than in group CK, and no significant differences in the relative abundance of other FRGs, F-MRGs, or MGEs were observed between the three groups on day 3 and day 13. The microbial community structure in swine manure was significantly altered on day 3, and the altered community structure was restored on day 13. The FRGs and F-MRGs with the highest relative abundance were qacA and adeF, respectively, and Clostridium and Lactobacillus were the dominant bacterial genera carrying these genes in swine manure. In summary, a single treatment of intramuscular ENR transiently increased antibiotic concentrations and altered the microbial community structure in swine manure; however, this treatment did not significantly affect the abundance of FRGs and F-MRGs.

Structure-guided preparation of fuctional oil rich in 1,3-diacylglycerols and linoleic acid from Camellia oil by combi-lipase.

BACKGROUND: Diacylglycerol (DAG)-enriched oil has been attracting attention because of its nutritional benefits and biological functions, although the composition of its various free fatty acids (FFAs) and an unclear relationship between substrate and yield make it difficult to be identified and qualified with respect to its production. In the present study, linoleic acid-enriched diacylglycerol (LA-DAG) was synthesized and enriched from Camellia oil by the esterification process using the combi-lipase Lipozyme TL IM/RM IM system. RESULTS: The relationship between FFA composition and DAG species productivity was revealed. The results showed that heterogeneous FFA with a major constituent (more than 50%) exhibited higher DAG productivity and inhibited triacylglycerol productivity compared to homogeneous constituents. Joint characterization by high-performance liquid chromatography-evaporative light scattering detection, gas chromatography-mass spectrometry and ultra-performance liquid chromatography-heated electrospray ionization-tandem mass spectrometry identified that DAG components contained dilinoleic acid acyl glyceride, linoleyl-oleyl glyceride and dioleic acid acyl glyceride in esterification products. Under the optimum conditions, 60.4% 1,3-DAG and 61.3% LA-DAG in the crude product at 1 h reaction were obtained, and further purified to 81.7% LA-DAG and 94.7% DAG via silica column chromatography. CONCLUSION: The present study provides a guideline for the identification of DAG species, as well as a structure-guided preparation method of DAG-enriched oils via the cost-effective combi-lipase. © 2022 Society of Chemical Industry.

Ligand fishing based on cell surface display of enzymes for inhibitor screening.

Ligand fishing for screening of enzyme inhibitors from complex chemical systems using baits prepared by cell surface display of the enzyme is herein demonstrated for the first time. Tyrosine phosphatase 1B (PTP1B), used as a model enzyme in this work, is displayed on the surface of E. coli cells by using ice nucleation protein (INP) as the anchoring motif. Infusion of PTP1B is characterized by western blot, immunofluorescence, proteinase K accessibility, and enzyme activity assays. Surface displayed PTP1B exhibits a maximum of 5.62 ± 0.251 U/OD600 enzymatic activity and a better stability compared with free enzyme. PTP1B displayed cells are used as solid-phase extraction adsorbent in combination with HPLC-MS to screen the inhibitors from the extracts of Rhodiola rosea, a traditional Chinese medicinal plant. Among many well-known active ingredients only arbutin is fished out with an IC50 value of 20.5 ± 0.873 µM, showing the inhibitor screening is highly selective. Furthermore, the equilibrium dissociation constant (KD) of the complex of arbutin and PTP1B was determined to be 79.6 µM by localized surface plasma resonance (LSPR) assay. The proposed ligand fishing technique using recombinant cells as baits opens a new avenue for screening of active compounds from natural products with accuracy and specificity.

Oleic Acid Copolymer as A Novel Upconversion Nanomaterial to Make Doxorubicin-Loaded Nanomicelles with Dual Responsiveness to pH and NIR.

Oleic acid (OA) as main component of plant oil is an important solvent but seldom used in the nanocarrier of anticancer drugs because of strong hydrophobicity and little drug release. In order to develop a new type of OA nanomaterial with dual responses to pH and near infrared light (NIR) to achieve the intelligent delivery of anticancer drugs. The novel OA copolymer (mPEG-PEI-(NBS, OA)) was synthesized by grafting OA and o-nitrobenzyl succinate (NBS) onto mPEGylated polyethyleneimine (mPEG-PEI) by amidation reaction. It was further conjugated with NaYF4:Yb3+/Er3+ nanoparticles, and encapsulated doxorubicin (DOX) through self-assembly to make upconversion nanomicelles with dual response to pH and NIR. Drug release behavior of DOX, physicochemical characteristics of the nanomicelles were evaluated, along with its cytotoxic profile, as well as the degree of cellular uptake in A549 cells. The encapsulation efficiency and drug loading capacity of DOX in the nanomicelles were 73.84% ± 0.58% and 4.62% ± 0.28%, respectively, and the encapsulated DOX was quickly released in an acidic environment exposed to irradiation at 980 nm. The blank nanomicelles exhibited low cytotoxicity and excellent biocompatibility by MTT assay against A549 cells. The DOX-loaded nanomicelles showed remarkable cytotoxicity to A549 cells under NIR, and promoted the cellular uptake of DOX into the cytoplasm and nucleus of cancer cells. OA copolymer can effectively deliver DOX to cancer cells and achieve tumor targeting through a dual response to pH and NIR.

[Mechanism of Effects of Genistein on the Reproductive System of Prepubertal Male Rats].

OBJECTIVE: To study the effects of genistein (GEN) on reproductive system in prepubertal male rats. METHODS: Thirty SPF-rated male SD rats were randomly divided into control group (Con group), low-dose group (G1 group) and high-dose group (G2 group), with 10 rats in each group. Corn oil, 150 mg/kg and 300 mg/kg GEN dissolved in corn oil of equal volume were respectively administered every day and weighed the next day. After 6 weeks, the rats were sacrificed, and the testis, epididymis and prostate were dissected, and organ coefficients were calculated. Histopathological changes of testis was observed. The number of sperm was counted and the rate of sperm malformation was calculated. The concentrations of serum testosterone and estradiol were detected by radioimmunoassay. The protein phosphatase 2, regulatory subunit B, gamma (PPP2R2C) protein expression in testicular tissue was detected by immunofluorescence assay. The mRNA and protein expression levels of PPP2R2C and cyclin dependent protein kinases 2 (CDK2) in rat testis were detected by real-time quantitative fluorescence PCR (RT-qPCR) and Western blot, respectively. The protein phosphatase 2A (PP2A) activity in testicular tissue was detected by immunoprecipitation. RESULTS: There were no statistically significant differences in body mass, sperm number, serum estradiol and PP2A enzyme activity among the groups ( P>0.05). The pathological structure of testicular in G2 group was disordered. Sperm abnormality rate in G1 and G2 groups was higher than that in Con group ( P<0.05). Serum testosterone concentration in G2 group was lower than that in Con group ( P<0.05). The expression of PPP2R2C and CDK2 in G2 group was higher than that in Con group ( P<0.05), but the protein level was lower than that in Con group ( P<0.05). PPP2R2C protein was expressed in testicular tissue in each group. CONCLUSION: Long-term exposure to high dose (300 mg/kg) GEN during prepuberty may cause adverse effects on reproductive function in adult male rats. Further investigation is needed to determine whether PPP2R2C-PP2A-CDK2 phosphorylation pathway affects reproductive system in rats.