An n-Dimensional Chaotic Map with Application in Reversible Data Hiding for Medical Images.

The drawbacks of a one-dimensional chaotic map are its straightforward structure, abrupt intervals, and ease of signal prediction. Richer performance and a more complicated structure are required for multidimensional chaotic mapping. To address the shortcomings of current chaotic systems, an n-dimensional cosine-transform-based chaotic system (nD-CTBCS) with a chaotic coupling model is suggested in this study. To create chaotic maps of any desired dimension, nD-CTBCS can take advantage of already-existing 1D chaotic maps as seed chaotic maps. Three two-dimensional chaotic maps are provided as examples to illustrate the impact. The findings of the evaluation and experiments demonstrate that the newly created chaotic maps function better, have broader chaotic intervals, and display hyperchaotic behavior. To further demonstrate the practicability of nD-CTBCS, a reversible data hiding scheme is proposed for the secure communication of medical images. The experimental results show that the proposed method has higher security than the existing methods.

Contribution of elovl5a to Docosahexaenoic Acid (DHA) Synthesis at the Transcriptional Regulation Level in Common Carp, Cyprinus carpio.

Docosahexaenoic acid (DHA) is an essential nutrient for humans and plays a critical role in human development and health. Freshwater fish, such as the common carp (Cyprinus carpio), have a certain degree of DHA biosynthesis ability and could be a supplemental source of human DHA needs. The elongase of very-long-chain fatty acid 5 (Elovl5) is an important enzyme affecting polyunsaturated fatty acid (PUFA) biosynthesis. However, the function and regulatory mechanism of the elovl5 gene related to DHA synthesis in freshwater fish is not clear yet. Previous studies have found that there are two copies of the elovl5 gene, elovl5a and elovl5b, which have different functions. Our research group found significant DHA content differences among individuals in Yellow River carp (Cyprinus carpio var.), and four candidate genes were found to be related to DHA synthesis through screening. In this study, the expression level of elovl5a is decreased in the high-DHA group compared to the low-DHA group, which indicated the down-regulation of elovl5a in the DHA synthesis pathways of Yellow River carp. In addition, using a dual-luciferase reporter gene assay, we found that by targeting the 3'UTR region of elovl5a, miR-26a-5p could regulate DHA synthesis in common carp. After CRISPR/Cas9 disruption of elovl5a, the DHA content in the disrupted group was significantly higher than in the wildtype group; meanwhile, the expression level of elovl5a in the disrupted group was significantly reduced compared with the wildtype group. These results suggest that elovl5a may be down-regulating DHA synthesis in Yellow River carp. This study could provide useful information for future research on the genes and pathways that affect DHA synthesis.

Ythdf2-mediated STK11 mRNA decay supports myogenesis by inhibiting the AMPK/mTOR pathway.

An emerging research focus is the role of m6A modifications in mediating the post-transcriptional regulation of mRNA during mammalian development. Recent evidence suggests that m6A methyltransferases and demethylases play critical roles in skeletal muscle development. Ythdf2 is a m6A "reader" protein that mediates mRNA degradation in an m6A-dependent manner. However, the specific function of Ythdf2 in skeletal muscle development and the underlying mechanisms remain unclear. Here, we observed that Ythdf2 expression was significantly upregulated during myogenic differentiation, whereas Ythdf2 knockdown markedly inhibited myoblast proliferation and differentiation. Combined analysis of high-throughput sequencing, Co-IP, and RIP assay revealed that Ythdf2 could bind to m6A sites in STK11 mRNA and form an Ago2 silencing complex to promote its degradation, thereby regulating its expression and consequently, the AMPK/mTOR pathway. Furthermore, STK11 downregulation partially rescued Ythdf2 knockdown-induced impairment of proliferation and myogenic differentiation by inhibiting the AMPK/mTOR pathway. Collectively, our results indicate that Ythdf2 mediates the decay of STK11 mRNA, an AMPK activator, in an Ago2 system-dependent manner, thereby driving skeletal myogenesis by suppressing the AMPK/mTOR pathway. These findings further enhance our understanding of the molecular mechanisms underlying RNA methylation in the regulation of myogenesis and provide valuable insights for conducting in-depth studies on myogenesis.

Biomimetic affinity sensor for the ultrasensitive detection of neonicotinoids.

Multiple pesticides are often used in combination to protect crops from pests. This makes rapid on-site detection of pesticide contamination challenging. Herein, we describe a method for simultaneous detection of diverse neonicotinoid pesticides using a sensor that combines neonicotinoid-specific odorant-binding protein 2 (OBP2), which was cloned from an insect chemical sensing protein and modified gold nanoparticles with local surface plasmon resonance (LSPR)-based digital nanoplasmonometry (DiNM). When neonicotinoid pesticides bind to OBP2 on gold nanoparticles, the induced LSPR shift peak wavelength is too small to be measured using conventional LSPR immunoassays. DiNM records and compares the scattered image intensity in two adjacent wavelength bands, A and B, centered on the LSPR peak. It considers both the peak shift and the relative intensity change in these two bands, resulting in a significant LSPR signal enhancement. Then the spectral-image contrast was computed as the signal response. Using this approach, we obtained excellent limits of detection (LODs) of 1.4, 1.5, and 4.5 ppb for the neonicotinoids imidacloprid, acetamiprid, and dinotefuran, respectively. Blind tests demonstrated high positive and negative rates for teas, approximately 85 and 100%, respectively. Recombinant OBP2 produced in E. coli offers several advantages over antibodies, including high yield, time savings, and cost effectiveness. Moreover, this method is highly selective and sensitive to neonicotinoids, making it practical for field use.

Oct4 reduction contributes to testicular injury of unilateral testicular torsion in mice model and apoptotic death of Sertoli cells through mediating CIP2A expression.

This study explored the mechanism of ipsilateral testis injury after ipsilateral testicular torsion detorsion (T/D) and the potential testis-protective part of the octamer-binding transcription factor 4 (Oct4)-cancerous inhibitors of protein phosphatase 2A (CIP2A) axis in a T/D animal model and in ischemia-reperfusion (IR)-treated testicular Sertoli TM4 cells. Quantitative Polymerase chain reaction (PCR) and western blot (WB) confirmed the downregulation of both CIP2A and Oct4 expression in the testicular tissue from T/D mice compared with sham-operated mice. T/D model was then established in mice with upregulated Oct4 expression in the testis. Oct4 elevation restored CIP2A expression in testes after T/D treatment. Furthermore, we observed that an increase in Oct4 ameliorated the testicular damage caused by torsion in the testis. Biochemical analysis indicated that T/D treatment increased serum anti-sperm antibody levels, but reduced testosterone levels. Meanwhile, in testicular tissue, reactive oxygen species (ROS), malondialdehyde (MDA), and activity of testicular myeloperoxidase (MPO) enzymes were promoted, while glutathione peroxidase activity (GPx) was decreased by T/D injury. Notably, testicular Oct4 restoration partially counteracted the effect of T/D treatment on these biochemical indices. Hypoxia/reoxygenation (HR) treatment was applied to TM4 cells to mimic TT injury in vitro. A gain-of-function study showed that Oct4 overexpression partly counteracted the promoting role of HR in cell damage, apoptosis, and oxidative stress in TM4 cells. These observations provide novel insights into the possible biochemical mechanism underlying the mediation of the Oct4-CIP2A axis in T/D injury.

Simultaneous determination of 13 paralytic shellfish toxins and tetrodotoxin in marine shellfish by porous graphitic carbon solid-phase extraction and hydrophilic interaction chromatography-tandem mass spectrometry.

The lethal neurotoxins, paralytic shellfish toxins (PSTs), and tetrodotoxin (TTX) have recently been found in marine shellfish from many coastal states. Herein, we applied a sensitive and reliable ultra-performance hydrophilic interaction chromatography (HILIC)-tandem mass spectrometry (MS) method to determine 13 PSTs and TTX in marine shellfish using a porous carbon solid-phase extraction (SPE). This in-house validation study required the development of a novel chromatographic separation using a HILIC-Z column, which was necessary to retain highly polar compounds. Using acetonitrile as the organic phase and ammonium formate-formic acid buffer as the aqueous phase, the quantitative analysis was carried out with an external standard method in the multiple reaction monitoring modes using positive electrospray ionization. To reduce interference, 1% aqueous acetic acid extracts of the shellfish samples were cleaned up by ion-pair SPE using a porous graphitic carbon cartridge. The calibration curves for PSTs and TTX were linear (R2 > 0.995), and the sensitivity was good, with limits of detection (LODs) of 1.7-13.7 µg/kg, and limits of quantitation (LOQs) of 5.2-41.0 µg/kg. The recoveries were 76.5-95.5% with RSDs of 3.1-12.0%. Finally, We applied the method for the determination of PSTs and TTX in three batches of Nassarius showing excellent method accuracy against expected values.

A facile "off-on" fluorescence sensor for pentachlorophenol detection based on natural N and S co-doped carbon dots from crawfish shells.

Natural N and S co-doped carbon dots (NSCDs) were synthesized via hydrothermal synthesis using food-derived crawfish shells as green precursors. The relationship between quantum yield (QY) and protein content of six crawfish shells treated with different alkalis was investigated. The synthesized NSCDs displayed a large QY of 18.57 %, which was higher than most of the chitin-derived CDs. Due to the oxidation of hydroxyl radicals, adding H2O2 and horseradish peroxidase (HRP) quenched the fluorescence of NSCDs, resulting in a detection limit (LOD) of 1.25 µM for H2O2. The addition of pentachlorophenol (PCP) was supposed to consume part of the hydroxyl radicals and protect NSCDs from being oxidized. Accordingly, a facile and rapid "off-on" fluorescence sensor was developed to detect PCP with a LOD of 2.30 µM. Further, the method described was successfully used to detect PCP in three real samples.

Transcriptomic analysis reveals the genes involved in tetrodotoxin (TTX) accumulation, translocation, and detoxification in the pufferfish Takifugu rubripes.

Tetrodotoxin (TTX) is a potent marine neurotoxin that exists in a variety of aquatic and terrestrial organisms. Pufferfish in different habitats show great variation in their TTX contents. Exploring the genes involved in TTX metabolism could contribute to our understanding of the molecular mechanisms underlying TTX accumulation, translocation, and detoxification in pufferfish. In this study, transcriptomic analysis was used to identify the functional genes related to TTX metabolism in the blood, liver, and muscle of the toxic and non-toxic tiger puffer (Takifugu rubripes). A total of 6101 differentially expressed genes (DEGs) were obtained after transcriptomic analysis; of these, 2401 were identified in the blood, 2262 in the liver, and 1438 in the muscle. After enrichment analysis, fourteen genes encoding glutathione S-transferases (GSTs), glutathione peroxidase (GPx), thioredoxins (TXNs), superoxide dismutase (SOD), ATP-binding cassettes (ABCs), apolipoproteins (APOs), inhibitors of apoptosis protein (IAP), and solute carrier (SLC), which are mainly antioxidant enzymes, membrane transporters, or anti-apoptotic factors, were revealed in the blood. Thirty-six genes encoding SLCs, ABCs, long-chain-fatty-acid-CoA ligases (ACSLs), interleukin 6 cytokine family signal transducer (IL6ST), endoplasmic reticulum (ER), and heat shock protein family A (Hsp70) were involved in transmembrane transporter activity and innate immune response. Notably, a large number of slc genes were found to play critical and diverse roles in TTX accumulation and translocation in the liver of T. rubripes. Nine genes from the slc, hsp70, complement C5 (c5), acsl, er, and serpin peptidase inhibitor (serpin) gene families were found to participate in the regulation of protein processing and anti-apoptosis. These results reflect the diverse functions of genes closely related to TTX accumulation, translocation, and detoxification in T. rubripes.

Downregulation of NCL attenuates tumor formation and growth in HeLa cells by targeting the PI3K/AKT pathway.

BACKGROUND: Nucleolin (NCL, C23) is a multifunctional phosphoprotein that plays a vital role in modulating the survival, proliferationand apoptosis of cancer cells. However, the effects of NCL on cervical cancer and the underlying mechanisms behind this are poorly understood. METHODS: Lentiviral transfection technology was used to construct NCL knockdown cell lines. MTT, colony formation assays, and tumorigenic assays in vivo were performed to observe cell proliferation. HOECHST 33342 staining, flow cytometry, and caspase activity assay were used to test cell apoptosis. RNA-Seq, Western blotting, and RT-PCR were conducted to investigate the specific molecular mechanism. RESULTS: NCL knockdown inhibited cell proliferation and promoted apoptosis both in vivo and in vitro. Mechanistic studies revealed that NCL knockdown inhibited the PI3K/AKT pathway by upregulating FGF, ITGA, TNXB, VEGF, Caspase 3, and Bax, as well as by downregulating AKT, GNB4, CDK6, IL6R, LAMA, PDGFD, PPP2RSA and BCL-2. In addition, the expression levels of apoptosis-related genes after using a PI3K inhibitor LY294002 were consistent with shRNA studies, while treatment with a 740Y-P agonist showed the opposite effect. CONCLUSIONS: Our findings indicate that downregulation of NCL may be a novel treatment strategy forcervical cancer.

In Vitro Toxicological Investigation and Risk Assessment of E-Cigarette Aerosols Based on a Novel Solvent-Free Extraction Method.

Cigarettes, potentially safer alternatives to combustible cigarettes, have been reported to increase the health risk for long-term users, so accumulating information about their potential toxicity is of great concern. However, toxicological evaluations of e-cigarette aerosols are limited, which may be attributed to the lack of a simple and efficient extraction method. Here, we developed a high-speed centrifugal method for extracting e-cigarette aerosol collected mass (ACM) and prepared ACM samples of 26 representative e-cigarettes, and 10 samples were further selected based on their cytotoxicity for systematic toxicological assessments. The average extraction efficiency of ACM, primary aerosol components, and typical carbonyls exceeded 85%. The toxicological evaluation showed that the IC50 value range of e-cigarettes for cytotoxicity was 2-52 mg/mL ACM, all e-cigarettes can induce the risk of DNA damage, mitochondrial depolarization, and c-Jun-related signal disturbances; most e-cigarettes significantly caused disturbance of oxidative stress balance. E-cigarettes with higher cytotoxicity appeared to cause a higher degree of damage, while no e-cigarette promoted mutagenicity and cytochrome c release. The toxicity difference among e-cigarettes using nicotine equivalent was significantly lower than that of ACM. This study provides a novel extraction method and a comprehensive in vitro toxicity risk profile of e-cigarette aerosols.

Biosorption of Copper in Swine Manure Using Aspergillus and Yeast: Characterization and Its Microbial Diversity Study.

Dietary copper supplementation in the feed of piglets generally exceeds 250-800 mg/kg, where a higher quantity (>250 mg/kg) can promote growth and improve feed conversion. Despite the reported positive effects, 90% of copper is excreted and can accumulate and pollute the soil. Data indicate that fungi have a biosorptive capacity for copper. Thus, the objectives of the present experiment were to study the effects of adding different strains of fungi on the biosorptive capacity for copper in swine manure and to evaluate potential effects on microbiota profiles. Aspergillus niger (AN), Aspergillus oryzae (AO), and Saccharomyces cerevisiae (SC) were selected, and each added 0.4% into swine manure, which contain 250 mg/kg of copper. The incubations lasted for 29 days, and biosorption parameters were analyzed on the 8th (D8), 15th (D15), 22nd (D22), and 29th (D29) day. Results showed that after biosorption, temperature was 18.47-18.77°C; pH was 6.33-6.91; and content of aflatoxin B1, ochratoxin A, and deoxynivalenol were low. In addition, residual copper concentration with AN was the lowest on D15, D22, and D29. The copper biosorption rate was also highest with AN, averaging 84.85% on D29. Biosorption values for AO reached 81.12% and for SC were lower than 80%. Illumina sequencing of 16S and ITS rRNA gene revealed that fungal treatments reduced the diversity and richness of fungal abundance, but had no effect on bacterial abundance. Unknown_Marinilabiliaceae, Proteiniphilum, Tissierella, and Curvibacter were the dominant bacteria, while Aspergillus and Trichoderma were the dominant fungi. However, the added strain of S. cerevisiae was observed to be lower than the dominant fungi, which contained less than 0.05%. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment predicted via PICRUSt2 that there were bacterial genes potentially related to various aspects of metabolism and environmental information processing. Overall, data indicated that Aspergillus can provide microbial materials for adsorption of copper.

Genomic Analysis of Delftia tsuruhatensis Strain TR1180 Isolated From A Patient From China With In4-Like Integron-Associated Antimicrobial Resistance.

Delftia tsuruhatensis has become an emerging pathogen in humans. There is scant information on the genomic characteristics of this microorganism. In this study, we determined the complete genome sequence of a clinical D. tsuruhatensis strain, TR1180, isolated from a sputum specimen of a female patient in China in 2019. Phylogenetic and average nucleotide identity analysis demonstrated that TR1180 is a member of D. tsuruhatensis. TR1180 exhibited resistance to ß-lactam, aminoglycoside, tetracycline and sulphonamide antibiotics, but was susceptible to phenicols, fluoroquinolones and macrolides. Its genome is a single, circular chromosome measuring 6,711,018 bp in size. Whole-genome analysis identified 17 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, as well as 24 potential virulence factors and a number of metal resistance genes. Our data showed that Delftia possessed an open pan-genome and the genes in the core genome contributed to the pathogenicity and resistance of Delftia strains. Comparative genomics analysis of TR1180 with other publicly available genomes of Delftia showed diverse genomic features among these strains. D. tsuruhatensis TR1180 harbored a unique 38-kb genomic island flanked by a pair of 29-bp direct repeats with the insertion of a novel In4-like integron containing most of the specific antibiotic resistance genes within the genome. This study reports the findings of a fully sequenced genome from clinical D. tsuruhatensis, which provide researchers and clinicians with valuable insights into this uncommon species.

Identification and characteristics of a novel aminoglycoside phosphotransferase, APH(3')-IId, from an MDR clinical isolate of Brucella intermedia.

OBJECTIVES: To describe a novel chromosomal aminoglycoside phosphotransferase named APH(3')-IId identified in an MDR Brucella intermedia ZJ499 isolate from a cancer patient. METHODS: Species identity was determined by PCR and MALDI-TOF MS analysis. WGS was performed to determine the genetic elements conferring antimicrobial resistance. Gene cloning, transcriptional analysis and targeted gene deletion, as well as protein purification and kinetic analysis, were performed to investigate the mechanism of resistance. RESULTS: APH(3')-IId consists of 266 amino acids and shares the highest identity (48.25%) with the previously known APH(3')-IIb. Expression of aph(3')-IId in Escherichia coli decreased susceptibility to kanamycin, neomycin, paromomycin and ribostamycin. The aph(3')-IId gene in ZJ499 was transcriptionally active under laboratory conditions and the relative abundance of this transcript was unaffected by treatment with the above four antibiotics. However, deletion of aph(3')-IId in ZJ499 results in decreased MICs of these drugs. The purified APH(3')-IId showed phosphotransferase activity against kanamycin, neomycin, paromomycin and ribostamycin, with catalytic efficiencies (kcat/Km) ranging from ∼105 to 107 M-1 s-1. Genetic environment and comparative genomic analyses suggested that aph(3')-IId is probably a ubiquitous gene in Brucella, with no mobile genetic elements detected in its surrounding region. CONCLUSIONS: APH(3')-IId is a novel chromosomal aminoglycoside phosphotransferase and plays an important role in the resistance of B. intermedia ZJ499 to kanamycin, neomycin, paromomycin and ribostamycin. To the best of our knowledge, APH(3')-IId represents the fourth characterized example of an APH(3')-II enzyme.

Transcriptionomic Study on Apoptosis of SKOV-3 Cells Induced by Phycoerythrin from Gracilaria lemaneiformis.

OBJECTIVE: To investigate the effects of Phycoerythrin (PE) on the human ovarian cancer cell line SKOV-3 and its antitumor mechanisms from a transcriptional point of view. METHODS: SKOV-3 cells were exposed to different concentrations of phycoerythrin. The efficiency of this treatment was evaluated through cell growth inhibition, changes in cell morphology, apoptosis and intracellular ROS levels. High throughput sequencing (RNA-seq) was performed to screen Differentially Expressed Genes (DEGs), which was verified using RT-PCR and Western blotting. RESULTS: PE showed a significant inhibitory effect on the growth of SKOV-3 cells in a time- and dose-dependent manner. H&E staining, electron microscopy and flow cytometry revealed that PE induced apoptosis in SKOV-3 cells. Transcriptome analysis showed that 2963 genes were differentially expressed between untreated or PEtreated cells. GO and KEGG pathway analyses identified 16 classical pathways that were enriched. We verified 8 DEGs including, JNK, GADD45A, EDEM2, RAD23, UBQLN, CAPN1, XBP1, and OS9. These results were consistent with the results from transcriptional sequences. CONCLUSION: The inhibitory effect of PE on SKOV-3 cells was a result of interaction with multiple pathways and signaling molecules. Among these, the ROS/JNK/Bcl-2 signaling pathway, upregulation of JNK, GADD45A and RAD23 as well as downregulation of XBP1 and OS9 played a critical role in the PE -induced apoptosis in human ovarian cancer cells.

Analysis of Resistance to Florfenicol and the Related Mechanism of Dissemination in Different Animal-Derived Bacteria.

Bacterial resistance to antibiotics has become an important concern for public health. This study was aimed to investigate the characteristics and the distribution of the florfenicol-related resistance genes in bacteria isolated from four farms. A total of 106 florfenicol-resistant Gram-negative bacilli were examined for florfenicol-related resistance genes, and the positive isolates were further characterized. The antimicrobial sensitivity results showed that most of them (100, 94.33%) belonged to multidrug resistance Enterobacteriaceae. About 91.51% of the strains carried floR gene, while 4.72% carried cfr gene. According to the pulsed-field gel electrophoresis results, 34 Escherichia coli were subdivided into 22 profiles, the genetic similarity coefficient of which ranged from 80.3 to 98.0%. The multilocus sequence typing (MLST) results revealed 17 sequence types (STs), with ST10 being the most prevalent. The genome sequencing result showed that the Proteus vulgaris G32 genome consists of a 4.06-Mb chromosome, a 177,911-bp plasmid (pG32-177), and a 51,686-bp plasmid (pG32-51). A floR located in a drug-resistant region on the chromosome of P. vulgaris G32 was with IS91 family transposase, and the other floR gene on the plasmid pG32-177 was with an ISCR2 insertion sequence. The cfr gene was located on the pG32-51 flanked by IS26 element and TnpA26. This study suggested that the mobile genetic elements played an important role in the replication of resistance genes and the horizontal resistance gene transfer.

Prevalence of Aminoglycoside Resistance Genes and Molecular Characterization of a Novel Gene, aac(3)-IIg, among Clinical Isolates of the Enterobacter cloacae Complex from a Chinese Teaching Hospital.

Members of the Enterobacter cloacae complex are important opportunistic human pathogens capable of causing a wide variety of infections. During recent decades, aminoglycoside-resistant E. cloacae complex isolates have increasingly been reported and have become a major concern. Here, we employed high-throughput sequencing in combination with specific PCR assays to investigate the prevalence of aminoglycoside resistance genes among 170 isolates of the E. cloacae complex collected from a teaching hospital in Wenzhou, China. A total of 12 known genes [aphA-1, strA, strB, aac(6')-IIc, aadA2, aac(3)-IId, aadB, aadA1, rmtB, armA, aadA5, and aac(6')-Ie-aph(2'')-Ia] and 1 novel gene [aac(3)-IIg] were identified, with aphA-1 (71.18%), strA (55.29%), and strB (52.35%) being the most prevalent, and aac(3)-IIg was detected with a positive rate of 21.76% (37/170). The aac(3)-IIg gene was 810 bp in length and encoded a protein that shared 72 to 78% identities with previously known AAC(3)-II aminoglycoside 3-N-acetyltransferases. The MICs of gentamicin and tobramycin were 512 µg/ml and 64 µg/ml, respectively, when aac(3)-IIg was cloned into Escherichia coli DH5α. All aac(3)-IIg-positive isolates exerted broad aminoglycoside resistance profiles, mediated by the coexistence of multiple resistance genes. Moreover, aminoglycoside resistance and resistance genes were found to be transferable in most strains (24/37). Nevertheless, pulsed-field gel electrophoresis (PFGE) and dendrogram analysis showed clonal diversity among these isolates. S1 nuclease PFGE, Southern hybridization, and whole-genome sequencing indicated that aac(3)-IIg was located on transferable as well as nontransferable plasmids of various sizes. The analysis of the genetic environment suggested that aac(3)-IIg is embedded within a class 1 integron, with IS26 playing an important role in its mobility.

Genomic and functional characterization of fecal sample strains of Proteus cibarius carrying two floR antibiotic resistance genes and a multiresistance plasmid-encoded cfr gene.

The objective of this study was to investigate the molecular characteristics and horizontal transfer of florfenicol resistance gene-related sequences in Proteus strains isolated from animals. A total of six Proteus strains isolated from three farms between 2015 and 2016 were screened by polymerase chain reaction (PCR) for known florfenicol resistance genes. Proteus cibarius G11, isolated from the fecal material of a goose, was found to harbor both cfr and floR genes. Whole genome sequencing revealed that the strain harbored two copies of the floR gene: one was located on the chromosome and the other was located on a plasmid named pG11-152. Two floR-containing fragments 4028 bp in length were identical and showed transposon-like structures. The cfr gene was found on a plasmid named pG11-51 and flanked by a pair of IS26s. Thus, mobile genetic elements played an important role in floR replication and horizontal resistance gene transfer. Therefore, increasing attention should be paid to monitoring the spread of resistance genes and resistance in real time.

PAU-1, a Novel Plasmid-Encoded Ambler Class A ß-Lactamase Identified in a Clinical Pseudomonas aeruginosa Isolate.

PURPOSE: The aim of this work was to identify a novel ß-lactamase gene bla PAU-1 encoded on the plasmid of a clinical Pseudomonas aeruginosa isolate. MATERIALS AND METHODS: The clinical P. aeruginosa isolates were isolated from a hospital in southern China. Molecular cloning was performed to analyze the function of the resistance gene. The minimum inhibitory concentration (MIC) was determined by means of the agar dilution method to determine the antimicrobial susceptibilities of the strains. Whole-genome sequencing and comparative genomics analysis were performed to analyze the structures of the resistance gene-related sequences. RESULTS: PAU-1 is a molecular class A, Bush-Jacoby group 2be enzyme which encoded 293 amino acids and shared 74% amino acid identity with a putative class A ß-lactamase from Rhodoferax saidenbachensis. Cloned bla PAU-1 in Escherichia coli and P. aeruginosa conferred resistance to piperacillin and ampicillin, and elevated the MIC with a 2-3 dilution for some oxyimino-ß-lactams in P. aeruginosa. The genetic environment of bla PAU-1 is tnpA-res-hp-relE-bla PAU-1-lysR, which is in accordance with the structure of a Tn3 transposon. Epidemiological investigation of bla PAU-1 in the same district did not show any evidences of molecular dissemination associated with this determinant. CONCLUSION: A novel class A ß-lactamase gene, bla PAU-1, associated with the mobile genetic element was identified on a transferable plasmid in a clinical P. aeruginosa isolate. Strict surveillance for the emergence of the new determinant should be established and an effort should be made to block the dissemination of this determinant.

In Situ Formation of Ti47Cu38Zr7.5Fe2.5Sn2Si1Nb2 Amorphous Coating by Laser Surface Remelting.

In previous studies, Ti-based bulk metallic glasses (BMGs) free from Ni and Be were developed as promising biomaterials. Corresponding amorphous coatings might have low elastic modulus, remarkable wear resistance, good corrosion resistance, and biocompatibility. However, the amorphous coatings obtained by the common methods (high velocity oxygen fuel, laser cladding, etc.) have cracks, micro-pores, and unfused particles. In this work, a Ti-based Ti47Cu38Zr7.5Fe2.5Sn2Si1Nb2 amorphous coating with a maximum thickness of about 100 µm was obtained by laser surface remelting (LSR). The in-situ formation makes the coating dense and strongly bonded. It exhibited better corrosion resistance than the matrix and its corrosion mechanism was discussed. The effects of LSR on the microstructural evolution of Ti-based prefabricated alloy sheets were investigated. The nano-hardness in the heat affected zone (HAZ) was markedly increased by 51%, meanwhile the elastic modulus of the amorphous coating was decreased by 18%. This demonstrated that LSR could be an effective method to manufacture the high-quality amorphous coating. The in-situ amorphous coating free from Ni and Be had a low modulus, which might be a potential corrosion-resistant biomaterial.

Induction of goat bone marrow mesenchymal stem cells into putative male germ cells using mRNA for STRA8, BOULE and DAZL.

Bone mesenchymal stem cells (BMSCs) have the capacity to differentiate into germ cells (GCs). This study was conducted to develop a non-integrated method of using RNA transfection to derive putative male GCs from goat BMSCs (gBMSCs) in vitro by overexpressing STRA8, BOULE and DAZL. The gBMSCs were induced by co-transfection these three mRNAs together (mi-SBD group) or sequential transfection according to their expression time order in vivo (mi-S + BD group). After transfection, a small population of gBMSCs transdifferentiated into early germ cell-like cells and had the potential to enter meiosis. These cells expressed primordial germ cell specific genes STELLA, C-KIT and MVH, as well as premeiotic genes DAZL, BOULE, STRA8, PIWIL2 and RNF17. Importantly, the expression level of meiotic marker synaptonemal complex protein 3 significantly increased in these transfected two groups compared with control cells by qRT-PCR, immunofluorescence and western blot analysis (P < 0.05). Moreover, the protein expression of MVH was significantly higher in mi-S + BD group than that in mi-SBD group (P < 0.05). In addition, compared with control group, the methylation rate of imprinted gene H19 decreased in these two transfected group (P < 0.05), and the rate was significantly lower in mi-S + BD group compared with mi-SBD group (P < 0.05). This study helps to understand the mechanisms of action of key genes in GCs differentiation and also provides a novel system for in vitro induction of male GCs from stem cells.