ABSTRACT
Jumbo phages are a group of tailed bacteriophages with large genomes and capsids. As a prototype of jumbo phage, ΦKZ infects Pseudomonas aeruginosa, a multi-drug-resistant (MDR) opportunistic pathogen leading to acute or chronic infection in immunocompromised individuals. It holds potential to be used as an antimicrobial agent and as a model for uncovering basic phage biology. Although previous low-resolution structural studies have indicated that jumbo phages may have more complicated capsid structures than smaller phages such as HK97, the detailed structures and the assembly mechanism of their capsids remain largely unknown. Here, we report a 3.5-Å-resolution cryo-EM structure of the ΦKZ capsid. The structure unveiled ten minor capsid proteins, with some decorating the outer surface of the capsid and the others forming a complex network attached to the capsid's inner surface. This network seems to play roles in driving capsid assembly and capsid stabilization. Similar mechanisms of capsid assembly and stabilization are probably employed by many other jumbo viruses.
Subject(s)
Capsid Proteins , Capsid , Cryoelectron Microscopy , Pseudomonas aeruginosa , Capsid/ultrastructure , Capsid/chemistry , Capsid/metabolism , Capsid Proteins/chemistry , Capsid Proteins/metabolism , Pseudomonas aeruginosa/virology , Virus Assembly , Pseudomonas Phages/ultrastructure , Pseudomonas Phages/chemistry , Bacteriophages/physiology , Bacteriophages/chemistry , Bacteriophages/ultrastructure , Models, Molecular , Genome, ViralABSTRACT
A rapid, accurate, non-sputum-based triage test for diagnosing tuberculosis (TB) is a high-priority need. Cepheid developed a novel prototype blood test, Xpert Mycobacterium tuberculosis Host Response (Xpert-MTB-HR), which generates a TB score based on the mRNA expression of three genes. We conducted a case-control study with prospective recruitment to evaluate its accuracy in the clinic of the Wusheng County Centers for Disease Prevention and Control in China. We enrolled 149 TB patients, 248 other respiratory diseases (ORD) patients, and 193 healthy controls. In addition, whole-blood samples taken from TB patients after 2, 5, and 6 months of treatment were tested with Xpert-MTB-HR to evaluate its ability to monitor treatment response. Xpert-MTB-HR discriminated between TB and healthy controls with an area under the curve (AUC) of 0.912 (95% CI, 0.878-0.945). With the specificity of 70% envisioned for a triage test, its sensitivity was 90.1% (84.9%-94.6%). Xpert-MTB-HR discriminated between TB and ORD with an AUC of 0.798 (0.750-0.847), and at specificity of 70%, the sensitivity was only 75.8% (68.5%-82.8%). In patients determined by Ultra to have medium or high sputum bacillary loads, with specificity of 70%, the sensitivity for discriminating patients with TB from healthy controls was 100.0% (100.0-100.0) and from patients with ORD, 95.1% (89.8-100.0). The TB scores generally increased by 2 months of treatment and then remained stable. Xpert-MTB-HR met the criteria for a triage test to discriminate between TB and healthy controls, but not between TB and ORD, except when limited to patients with high sputum bacillary loads. Xpert-MTB-HR showed promise for monitoring response to treatment but needs to be further evaluated in larger prospective studies.
Subject(s)
Antibiotics, Antitubercular , Mycobacterium tuberculosis , Tuberculosis, Pulmonary , Tuberculosis , Humans , Tuberculosis, Pulmonary/diagnosis , Tuberculosis, Pulmonary/drug therapy , Tuberculosis, Pulmonary/microbiology , Prospective Studies , Rifampin , Antibiotics, Antitubercular/therapeutic use , Case-Control Studies , Sensitivity and Specificity , Tuberculosis/diagnosis , Tuberculosis/drug therapy , Mycobacterium tuberculosis/genetics , Sputum/microbiology , ChinaABSTRACT
The Xpert MTB/RIF Ultra (Ultra) is not yet used for the diagnosis of tuberculosis (TB) in China. We compared the performance of the Xpert and Ultra for detecting Mycobacterium tuberculosis and rifampicin resistance in a primary-level clinic in rural China. Sputum samples from suspected pulmonary TB patients were collected and subjected to smear microscopy, liquid culture, Xpert and Ultra tests. We then compared the sensitivity and specificity of Xpert and Ultra for diagnosing TB against liquid culture. Whole-genome sequencing was performed to predict rifampicin resistance and the results were compared with the Xpert and Ultra tests. The sensitivities of Xpert and Ultra were 88.1% and 95.1%, and the specificities were 91.9% and 84.4%, respectively. Among the 61 smear-negative culture-positive patients, the sensitivities of Xpert and Ultra were 80.3% and 91.8%. All Xpert-positive patients were Ultra-positive. Among culture-negative Xpert or Ultra-positive patients, 69.6% were taking anti-TB drugs or had a previous history of TB. Of the samples that Ultra classified as trace, nearly 25% were probably false-positives. Both Xpert and Ultra accurately detected all rifampicin-resistant patients. In conclusion, Ultra was more sensitive than Xpert, especially for smear-negative patients but had decreased specificity with more false-positives, especially with Ultra trace results.
Subject(s)
Mycobacterium tuberculosis , Tuberculosis, Pulmonary , Humans , Mycobacterium tuberculosis/genetics , Rifampin/pharmacology , Rifampin/therapeutic use , Antitubercular Agents , Tuberculosis, Pulmonary/diagnosis , Tuberculosis, Pulmonary/drug therapy , China/epidemiologyABSTRACT
The fitness of multidrug-resistant tuberculosis (MDR-TB) is thought to be an important determinant of a strain's ability to be transmitted. Studies in the laboratory have demonstrated that MDR-TB strains have reduced fitness but the relative transmissibility of MDR-TB versus drug-susceptible (DS) TB strains in human populations remains unresolved. We used data on genomic clustering from our previous molecular epidemiological study in Songjiang (2011-2020) and Wusheng (2009-2020), China, to compare the relative transmissibility of MDR-TB versus DS-TB. Genomic clusters were defined with a threshold distance of 12-single-nucleotide-polymorphisms and the risk for MDR-TB clustering was analyzed by logistic regression. In total, 2212 culture-positive pulmonary TB patients were enrolled in Songjiang and 1289 in Wusheng. The clustering rates of MDR-TB and DS-TB strains were 19.4% (20/103) and 26.3% (509/1936), respectively in Songjiang, and 43.9% (29/66) and 26.0% (293/1128) in Wusheng. The risk of MDR-TB clustering was 2.34 (95% CI 1.38-3.94) times higher than DS-TB clustering in Wusheng and 0.64 (95% CI 0.38-1.06) times lower in Songjiang. Neither lineage 2, compensatory mutations nor rpoB S450L were significantly associated with MDR-TB transmission, and katG S315â T increased MDR-TB transmission only in Wusheng (OR 5.28, 95% CI 1.42-19.21). MDR-TB was not more transmissible than DS-TB in either Songjiang or Wusheng. It appears that the different transmissibility of MDR-TB in Songjiang and Wusheng is likely due to differences in the quality of the local TB control programmes. Suggesting that the most effective way to control MDR-TB is by improving local TB control programmes.
Subject(s)
Mycobacterium tuberculosis , Tuberculosis, Multidrug-Resistant , Tuberculosis, Pulmonary , Humans , Mycobacterium tuberculosis/genetics , Antitubercular Agents/pharmacology , Antitubercular Agents/therapeutic use , Tuberculosis, Multidrug-Resistant/microbiology , Tuberculosis, Pulmonary/epidemiology , Tuberculosis, Pulmonary/microbiology , Mutation , China/epidemiology , Drug Resistance, Multiple, Bacterial/genetics , Microbial Sensitivity TestsABSTRACT
Giant viruses are a large group of viruses that infect many eukaryotes. Although components that do not obey the overall icosahedral symmetry of their capsids have been observed and found to play critical roles in the viral life cycles, identities and high-resolution structures of these components remain unknown. Here, by determining a near-atomic-resolution, five-fold averaged structure of Paramecium bursaria chlorella virus 1, we unexpectedly found the viral capsid possesses up to five major capsid protein variants and a penton protein variant. These variants create varied capsid microenvironments for the associations of fibers, a vesicle, and previously unresolved minor capsid proteins. Our structure reveals the identities and atomic models of the capsid components that do not obey the overall icosahedral symmetry and leads to a model for how these components are assembled and initiate capsid assembly, and this model might be applicable to many other giant viruses.
Subject(s)
Chlorella , Giant Viruses , Paramecium , Phycodnaviridae , Phycodnaviridae/genetics , Capsid/chemistry , Capsid Proteins/genetics , Capsid Proteins/chemistryABSTRACT
ABSTRACTTuberculosis (TB) is more prevalent in rural than urban areas in China, and delineating TB transmission patterns in rural populations could improve TB control. We conducted a prospective population-based study of culture-positive pulmonary TB patients diagnosed between July 1, 2009 and December 31, 2020 in two rural counties in China. Genomic clusters were defined with a threshold distance of 12-single-nucleotide-polymorphisms, based on whole-genome sequencing. Risk factors for clustering were identified by logistic regression. Transmission links were sought through epidemiological investigation of genomic-clustered patients. Of 1517 and 751 culture-positive pulmonary TB patients in Wusheng and Wuchang counties, respectively, 1289 and 699 strains were sequenced. Overall, 624 (31.4%, 624/1988) patients were grouped into 225 genomic clusters. Epidemiological links were confirmed in 41.8% (196/469) of clustered isolates, including family (32.7%, 64/196) and social contacts (67.3%, 132/196). Social contacts were generally with relatives, within the community or in shared aggregated settings outside the community, but the proportion of clustered contacts in each category differed between the two sites. The time interval between diagnosis of student cases and contacts was significantly shorter than family and social contacts, probably due to enhanced student contact screening. Transmission of multidrug-resistant (MDR) strains was likely responsible for 81.4% (83/102) of MDR-TB cases, with minimal acquisition of additional resistance mutations. A large proportion of TB transmission in rural China occurred among social contacts, suggesting that active screening and aggressive contact tracing could benefit TB control, but contact screening should be tailored to local patterns of social interactions.
Subject(s)
Mycobacterium tuberculosis , Tuberculosis, Multidrug-Resistant , Tuberculosis, Pulmonary , Tuberculosis , Antitubercular Agents/therapeutic use , China/epidemiology , Genomics , Humans , Mycobacterium tuberculosis/genetics , Prospective Studies , Rural Population , Tuberculosis/drug therapy , Tuberculosis/epidemiology , Tuberculosis, Multidrug-Resistant/drug therapyABSTRACT
Recurrent tuberculosis (TB) in China has been studied in urban areas but not in rural settings. We conducted a retrospective cohort study on all successfully treated bacteriologically confirmed TB patients between 2009 and 2020 in Wusheng County, Sichuan Province using whole-genome sequencing (WGS). Isolates differing by ≤ 12 single nucleotide polymorphisms (SNPs) were considered relapse, otherwise were considered exogenous reinfection, and molecular drug susceptibility results were also compared. In total, 4.9% (75/1532) of successfully treated cases had subsequent bouts of TB, with 4 patients having two subsequent bouts, yielding a total of 79 events and a rate of 8.56 (95% CI 6.86-10.67) cases per 1000 person years, 8.9 times higher than in the general population. Most recurrences (74.4%, 58/79) occurred within three years. The risk for recurrent TB was increased for men and patients with drug-resistant isolates. Among the 44 recurrent events with genotyped paired isolates, 39 were classified as relapse and 5 as exogenous reinfection. Ten (25%, 10/40) recurrent patients acquired new resistance during treatment. Recurrent TB in rural Wusheng was mostly relapse and associated with drug resistance, suggesting the need to improve patient management, resistance testing and patient follow-up for at least 3 years after completing treatment.
Subject(s)
Tuberculosis , Antitubercular Agents/therapeutic use , China/epidemiology , Female , Humans , Male , Recurrence , Reinfection , Retrospective Studies , Tuberculosis/diagnosis , Tuberculosis/drug therapy , Tuberculosis/epidemiology , Tuberculosis, Multidrug-Resistant/diagnosis , Tuberculosis, Multidrug-Resistant/drug therapy , Tuberculosis, Multidrug-Resistant/epidemiologyABSTRACT
With the increasing demand for pollinating services, the wellness of honeybees has received widespread attention. Recent evidence indicated honeybee health might be posed a potential threat by widely used neonicotinoids worldwide. However, little is known about the molecular mechanism of these insecticides in honeybees especially at an enantiomeric level. In this study, we selected two species of bees, Apis mellifera (A. mellifera) and Apis cerana (A. cerana), to assess the toxicity and molecular mechanism of neonicotinoid dinotefuran and its enantiomers. The results showed that S-dinotefuran was more toxic than rac-dinotefuran and R-dinotefuran to honeybees by oral and contact exposures as much as 114 times. A. cerana was more susceptible to highly toxic enantiomer S-dinotefuran. S-dinotefuran induced the immune system response in A. cerana after 48 h exposure and significant changes were observed in the neuronal signaling of A. mellifera under three forms of dinotefuran exposure. Moreover, molecular docking also revealed that S-dinotefuran formed more hydrogen bonds than R-dinotefuran with nicotinic acetylcholine receptor, indicating the higher toxicity of S-dinotefuran. Data provided here show that R-dinotefuran may be a safer alternative to control pests and protect pollinators than rac-dinotefuran.
Subject(s)
Guanidines , Nitro Compounds , Animals , Bees , Guanidines/chemistry , Guanidines/toxicity , Molecular Docking Simulation , Neonicotinoids/toxicity , Nitro Compounds/chemistry , Nitro Compounds/toxicityABSTRACT
Banker plant systems can be used to sustain a reproducing population of biological control agents (BCAs) within a crop, thus providing long-term pest suppression. The founder population of natural enemies in banker plant systems is usually mass-reared on factitious hosts. Thus, a better understanding of the population fitness and pest control performance of mass-reared BCAs in the field is crucial when developing integrated pest management (IPM) strategies. In this study, we determined the fitness of the generalist predator, Chrysopa pallens (Hemiptera: Chrysopidae) ever cultured on different food sources (i.e., mass rearing food, Corcyra cephalonica eggs, and aphid food, Megoura japonica) preying on Aphis craccivora in a banker plant system in a greenhouse based on Chi's age-stage, two-sex life table analysis method. The life tables and predation rate parameters of C. pallens were not significantly different between both treatments under fluctuating temperature conditions. Corcyracephalonica eggs did not significantly weaken the performances of C. pallens in a Vicia faba-A. craccivora banker plant system compared to aphids. In conclusion, C. cephalonica eggs can be used for the mass production of C. pallens as the founder population in a banker plant system. Moreover, linking the life table data with the predation rate is an effective strategy for evaluating mass rearing programs in establishing banker plant systems.
ABSTRACT
A separation and analysis method of fosthiazate stereoisomers was established utilizing supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) with a CHIRALPAK AD-3 column. The determination of the four fosthiazate stereoisomers could be completed within 6 min. The environmental behaviors of fosthiazate stereoisomers were studied in legume vegetables. After applying fosthiazate granules to soil, the concentrations of fosthiazate stereoisomers in the legume vegetables increased with time, reached maximum values in 7-10 days, and then decreased gradually in all legumes except for in Glycine max. No obvious dissipation behaviors were observed in Glycine max. Interestingly, the stereoselective behaviors were species-specific. A-(-), B-(-) and B-(±)-fosthiazate were preferentially enriched in Phaseolus vulgaris Linn and Vigna unguiculata, while A-(+) and A-(±)-fosthiazate preferentially accumulated in Vicia faba Linn, Pisum sativum Linn and G. max. The opposite stereoselectivity of B-(±)-fosthiazate was observed in different growth stage of G. max. No stereoselective dissipation occurred in soil.
Subject(s)
Fabaceae/chemistry , Organophosphorus Compounds/chemistry , Tandem Mass Spectrometry/methods , Thiazolidines/chemistry , Chromatography, Supercritical Fluid , Fabaceae/metabolism , Pisum sativum/chemistry , Pisum sativum/metabolism , Phaseolus/chemistry , Phaseolus/metabolism , Glycine max/chemistry , Glycine max/metabolism , Stereoisomerism , Vicia faba/chemistry , Vicia faba/metabolismABSTRACT
Quinestrol (QUN), a synthetic estrogen used as an oral contraceptive or emergency contraceptive component, has been shown to be an endocrine-disrupting chemical. To assess the environmental risk of QUN, batch equilibration experiments were conducted to investigate the adsorption-desorption of QUN in five contrasting soils from different areas of China. The leaching properties were also calculated based on the adsorption and degradation data from our previous study with the same soils. The Freundlich and Langmuir models were applied to the sorption-desorption data to examine the affinity towards QUN of the soils, which had varying physical and chemical properties. The Kf and Kfdes values of QUN in the tested soils ranged from 3.72 to 20.47 mg1-n Ln kg-1 and from 1.26 to 7.8 mg1-n Ln kg-1, respectively, and Qm ranged from 28.25 to 126.58 mg/kg. The desorption data showed that hysteresis occurred. The Kf and Kfdes values of QUN were positively correlated with the soil total organic carbon (OC) and cation exchange capacity (CEC), and it may be due to the content of TOC and CEC exhibited a positive correlation. A low mobility potential of QUN in soils was predicted and verified the adsorption results by the groundwater ubiquity score (GUS) and retardation factor (Rf).
ABSTRACT
Although esterase-mediated spinosad resistance has been proposed for several insects, the associated molecular mechanism remains poorly understood. In this study, we investigated the mechanism of esterase-based spinosad resistance in house flies using a susceptible strain (SSS) and a spinosad-resistant, near-isogenic line (N-SRS). Combined with the synergistic effect of DEF on spinosad in the N-SRS strain, decreased ali-esterase activity in the spinosad-resistant strain has implicated the involvement of mutant esterase in spinosad resistance in house flies. Examination of the carboxylesterase gene MdαE7 in the two strains revealed that four non-synonymous mutations (Trp251-Leu, Asp273-Glu, Ala365-Val, and Ile396-Val) may be associated with spinosad resistance in house flies. Single nucleotide polymorphism analysis further indicated a strong relationship between these four mutations and spinosad resistance. Moreover, quantitative real-time PCR revealed a female-linked MdαE7 expression pattern in the N-SRS strain, which may contribute to sex-differential spinosad resistance in house flies.
Subject(s)
Houseflies/physiology , Insecticide Resistance/genetics , Insecticides/toxicity , Macrolides/toxicity , Animals , Carboxylesterase/metabolism , Drug Combinations , Female , Houseflies/drug effectsABSTRACT
The fungicide myclobutanil (MYC) is a common contaminant found in surface water. The aim of this study was to determine the acute toxicity, developmental effects, bioconcentration factor (BCF) and potential bio-molecular mechanisms of MYC toxicity in zebrafish. Susceptibility to MYC toxicity was life-stage dependent with adult fish being the most sensitive (96 h-LC50, 6.34â¯mg/L) followed by 72â¯h post-hatch (hph) larvae (8.90â¯mg/L), 12 hph larvae (20.53â¯mg/L) and embryos (42.54â¯mg/L). Zebrafish embryos and larvae (12 hph) responded with decreased hatching, heartbeat and growth, as well as abnormal spontaneous movement and development. BCFs were calculated by quantifying MYC concentrations from different tissues of adult zebrafish exposed to MYC for up to 11 days. Highest BCFs were obtained from gills (18.25⯱â¯0.07), followed by viscera (16.78⯱â¯0.04), head (13.13⯱â¯0.08) and muscle (8.96⯱â¯0.10). MYC (0.5â¯mg/L) inhibited gene expression related to cholesterol synthesis pathway, including 24-dehydrocholesterol reductase (DHCR24), 7-dehydrocholesterol reductase (DHCR7), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCRa), HMGCRb, farnesyl-diphosphate farnesyltransferase 1(FDFT1), squa-lene epoxidase (SQLE), isopentenyl-diphosphate delta isomerase 1 (IDI1) and CYP51, while no cholesterol changes were observed in the MYC treated group. These results will contribute to the literature assessing the environmental risk of MYC in aquatic environment.
Subject(s)
Cholesterol/biosynthesis , Nitriles/toxicity , Triazoles/toxicity , Water Pollutants, Chemical/toxicity , Zebrafish/growth & development , Animals , Bioaccumulation , Cholesterol/genetics , Embryo, Nonmammalian/drug effects , Female , Fungicides, Industrial/toxicity , Larva/drug effects , Life Cycle Stages/drug effects , Male , Sex Factors , Zebrafish/metabolismABSTRACT
Indole-3-butyric acid (IBA) is an efficient plant growth regulator for promoting germination and the formation of rooting of various plants. Since it is unstable and presents the low utilization ratio, there is a compelling need to design an environmentally friendly formulation for IBA, which can reduce the loss of degradation and improve its utilization. Nano-sized controlled-release formulations can provide better durability and penetrate through the plant epidermis to efficiently deliver the agrochemicals to the target tissues. In this work, a kind of novel nano controlled-release formulation was prepared by conjugating the IBA and 3-glycidoxypropyltrimethoxysilane (GPTMS) through a covalent cross-linking reaction, and subsequently hydrolyzation and polycondensation with tetraethoxysilane. The resulting nanospheres were characterized by Fourier transform infrared spectroscopy, ultraviolet spectrophotometry, scanning electron microscope, and thermal gravity analysis. The results showed that the obtained nanospheres had a remarkable loading efficiency of IBA (about 43% w/w). The formation of covalent between IBA and GPTMS enabled the nanospheres with a good chemical stability that could protect against photo-degradation effectively. The released rate of the IBA from nanospheres was related to the temperature, pH value. With increased temperature as well as acidity and alkality, the release of the IBA was sped up. The IBA could also be released effectively from IBA-silica nanospheres by esterase, and the sustainable release characteristics of IBA-silica nanospheres were in conformity with the Ritger and Peppas equation. The IBA-silica nanospheres displayed excellent dual stimuli-responsive properties under esterase and weak acid conditions, and could obviously promote the growth of root and bud of pea. Thus, the IBA silica nanospheres prepared by covalent cross-linking reaction have a good potential application as a controlled-release formulation and environmentally-friendly plant growth regulator.
Subject(s)
Indoles/chemistry , Nanospheres/chemistry , Delayed-Action Preparations , Esterases/metabolism , Hydrogen-Ion Concentration , Light , Microscopy, Electron, Scanning , Models, Theoretical , Particle Size , Silicon Dioxide/chemistry , Spectroscopy, Fourier Transform Infrared , Temperature , ThermogravimetryABSTRACT
The dissipations of afidopyropen and its metabolite in wheat plant and soil were determined using a quick, easy, cheap, effective, rugged, and safe method with ultra-high performance liquid chromatography and tandem mass spectrometry under a field ecosystem. The limits of quantification were estimated for both target compounds as 0.001 mg/kg. The recoveries of afidopyropen and its metabolite ranged from 94 to 114% (soil), 90 to 109% (wheat seed) and 81 to 91% (wheat straw) at levels of 0.001, 0.01, 0.1, and 2.0 mg/kg with relative standard deviations ≤7%. The results of the residual dynamics experiments showed that afidopyropen dissipated rapidly in wheat plant and soil. Its metabolite initially showed a tendency of rapid increase followed by a decrease in wheat plant but could not be detected in soil. The data showed that the first + first-order model was more suitable for describing the decline of afidopyropen in wheat and soil. The half-lives of afidopyropen in wheat plant and soil were 1.65 and 1.21 days, respectively.
Subject(s)
Heterocyclic Compounds, 4 or More Rings/analysis , Lactones/analysis , Soil/chemistry , Triticum/chemistry , Chromatography, High Pressure Liquid , Heterocyclic Compounds, 4 or More Rings/metabolism , Lactones/metabolism , Molecular Structure , Tandem Mass SpectrometryABSTRACT
Kasugamycin is an aminoglycoside antibiotic originally isolated from Streptomyces kasugaensis, which has been widely used for the management of plant diseases. However, photo-thermal instability and low efficiency limit its application. Therefore, it is an urgent task to prevent unwanted loss of kasugamycin and ensure maximum bioactivity at target site. In this work, a novel formulation of kasugamycin that responds to different biological stimuli produced by pests was prepared using silica microcapsules crosslinked with pectin via special disulfide bonds. The results demonstrated that the silica-SS-pectin microcapsules had a high loading efficiency (20% w/w) and could effectively enhance the thermal and light stability of kasugamycin. The microcapsules displayed excellent pectinase and glutathione dual-responsive properties and the release kinetics investigated by Riger-Peppas model suggested combination of various release mechanisms. Compared with kasugamycin wettable powder, the microcapsules possessed sustained and improved antimicrobial efficacy against Erwinia carotovora. Thus, the dual-responsive microcapsules potentially have agricultural application as a controlled release system.
Subject(s)
Aminoglycosides/pharmacology , Anti-Infective Agents/pharmacology , Pectins/chemistry , Aminoglycosides/chemistry , Anti-Infective Agents/chemistry , Capsules , Drug Carriers , Pectobacterium carotovorum/drug effects , Plant Diseases/prevention & control , Silicon DioxideABSTRACT
Disease caused by Tomato yellow leaf curl virus (TYLCV) brings serious production losses of cultivated tomato worldwide. In our previous study, two novel amino acid derivatives exerted satisfactory antiviral activities against TYLCV. In this study, the variation of TYLCV, the transcriptional expression level of Ty-1 and the enzyme activities of POD and PPO in tomato were monitored after treatment with two amino acid derivatives to illustrate the antiviral mechanism. The results showed the symptom severity caused by TYLCV was reduced significantly by two compounds and was associated with the inhibition of viral DNA level at the early stage. Among three levels of concentration, the highest inhibition rate of CNBF-His was 40.66% at 1000 mg/L, for CNBF-Asn, the highest inhibition rate was 36.26% at 2000 mg/L 30 days post-inoculation. Two compounds could also enhance the activities of PPO and POD and the transcriptional expression level of Ty-1 which correlates with plant resistance in tomato. In the field test, two compounds increased the yields of tomato and the maximum increase of yield was 37.66%. This is the first report of novel amino acid derivatives inducing resistance in tomato plant against TYLCV. It is suggested that amino acid derivatives have the potential to be an effective approach against TYLCV in tomato plant.
Subject(s)
Amino Acids/chemistry , Begomovirus/drug effects , Plant Diseases/prevention & control , Solanum lycopersicum/virology , Amino Acids/chemical synthesis , Catechol Oxidase/metabolism , DNA, Viral/isolation & purification , Disease Resistance , Gene Expression Regulation, Plant , Solanum lycopersicum/drug effects , Solanum lycopersicum/enzymology , Solanum lycopersicum/genetics , Peroxidase/metabolism , Plant Diseases/virology , Plant Leaves/virology , Temperature , Transcription, GeneticABSTRACT
The controlled and targeted release of pesticides with high water solubility has been a challenge for integrated pest management. In this paper, kasugamycin, an antibiotic broadly used in plant disease control, was covalently conjugated to pectin to form a kasugamycin-pectin conjugate by an amide bond. The conjugate was structurally characterized by Fourier transform infrared spectroscopy, ultraviolet spectrophotometry, and thermal gravimetric analysis. The results showed that the conjugate was stable over a wide range of pH and temperatures, as well as under UV irradiation. When incubated with Pseudomonas syringae pv. lachrymans, the conjugate could be activated, releasing the kasugamycin, which made it a promising controlled-release formulation of pesticide.
Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/pharmacology , Delayed-Action Preparations/chemical synthesis , Delayed-Action Preparations/pharmacology , Pesticides/chemical synthesis , Pesticides/pharmacology , Pseudomonas syringae/drug effects , Aminoglycosides/chemistry , Anti-Bacterial Agents/chemistry , Delayed-Action Preparations/chemistry , Drug Carriers/chemistry , Drug Delivery Systems , Pectins/chemistry , Pesticides/chemistry , Plant Diseases/microbiology , Plant Diseases/prevention & control , Pseudomonas syringae/physiologyABSTRACT
Ractopamine (RAC) has been approved as a feed additive for swine, cattle or turkey, and is likely to have residue in edible animal products and may pose a potential risk for consumer health. Therefore, it is essential to establish a method to detect the residue of RAC in animal products. This work presents a rapid and sensitive HPLC method for the determination of RAC in pork samples with pre-column derivatization. The RAC derivative was separated on a kromasil C18 column and detected at 284nm with a UV detector. The detection capability (CCß) was 0.078µgg(-1) and the linearity was established over the concentration range of 0.15-100.0µgg(-1). The overall mean recovery in spike range of 0.2µgg(-1) to 100µgg(-1) was 89.9% with the overall mean relative standard deviation of 4.1%. This method can be used for the quantification of RAC in pork samples and help to establish adequate monitoring of the residue of RAC.
Subject(s)
Adrenergic beta-Agonists/analysis , Drug Residues/analysis , Food Contamination , Food Inspection/methods , Growth Substances/analysis , Meat/analysis , Phenethylamines/analysis , Adrenergic beta-Agonists/chemistry , Analytic Sample Preparation Methods , Animals , China , Chromatography, High Pressure Liquid , Chromatography, Reverse-Phase , Drug Residues/chemistry , Drug Stability , Fluorobenzenes/chemistry , Growth Substances/chemistry , Indicators and Reagents/chemistry , Limit of Detection , Nitro Compounds/chemistry , Phenethylamines/chemistry , Reproducibility of Results , Solid Phase Extraction , Spectrophotometry, Ultraviolet , Sus scrofaABSTRACT
Controlled release formulation of pesticides is an effective approach to achieve the desirable purpose of increasing the utilization of pesticides and reducing the environmental residuals. In this work, a novel functionalized microcapsule using silica cross-linked with alginate, and some beneficial elements to crops, was prepared. The microcapsules were structurally characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The results showed that the microcapsules had a high loading efficiency of prochloraz (about 30% w/w) and could effectively protect prochloraz against degradation under UV irradiation and alkaline conditions, showed sustainable release for at least 60 days, and also likely increased disease resistance due to the element on the surface. Given the advantages of the microcapsules, this delivery system may be extended to other photosensitive or pH-sensitive pesticides in the future.