Thermal Degradation and Product Analysis of 3-iodo-2-propyl-butylcarbamate as a Wood Preservative

The thermal degradation kinetics and degradation products of IPBC during the heating process are investigated herein. Experiments were conducted at isothermal conditions from 60 °C to 150 °C. The remaining IPBC content was analyzed by high-performance liquid chromatography (HPLC) at specific time intervals for each test, and the kinetic model of IPBC thermal degradation was established. The thermal degradation products of IPBC were studied by ultra-performance liquid chromatography-mass spectrometry (UPLC−MS/MS). The results showed that thermal degradation of IPBC occurred at 70 °C, and the degradation rate increased significantly from 70 °C to 150 °C. The thermal degradation kinetics of IPBC conformed to the first-order reaction and k=3.47×1012e−111125/RT from 60 °C to 150 °C. Seven degradation products such as prop-2-yn-1-yl ethylcarbamate and methyl N-butylcarbamate were identified and the degradation reaction pathway and the mechanism of IPBC were proposed, which involved deiodination, demethylation, deethynylation, deethylation, and hydroxylation processes

Resistance to the novel fungicide pyrimorph in Phytophthora capsici: risk assessment and detection of point mutations in CesA3 that confer resistance.

Pyrimorph is a novel fungicide with high activity against the plant pathogen Phytophthora capsici. We investigated the risk that P. capsici can develop resistance to pyrimorph. The baseline sensitivities of 226 P. capsici isolates, tested by mycelial growth inhibition, showed a unimodal distribution with a mean EC(50) value of 1.4261 (± 0.4002) µg/ml. Twelve pyrimorph-resistant mutants were obtained by repeated exposure to pyrimorph in vitro with a frequency of approximately 1 × 10(-4). The resistance factors of the mutants ranged from 10.67 to 56.02. Pyrimorph resistance of the mutants was stable after 10 transfers on pyrimorph-free medium. Fitness in sporulation, cystospore germination, and pathogenicity in the pyrimorph-resistant mutants was similar to or less than that in the parental wild-type isolates. On detached pepper leaves and pepper plants treated with the recommended maximum dose of pyrimorph, however, virulence was greater for mutants with a high level of pyrimorph resistance than for the wild type. The results suggest that the risk of P. capsici developing resistance to pyrimorph is low to moderate. Among mutants with a high level of pyrimorph resistance, EC(50) values for pyrimorph and CAA fungicides flumorph, dimethomorph, and mandipropamid were positively correlated. This indicated that point mutations in cellulose synthase 3 (CesA3) may confer resistance to pyrimorph. Comparison of CesA3 in isolates with a high level of pyrimorph resistance and parental isolates showed that an amino acid change from glutamine to lysine at position 1077 resulted in stable, high resistance in the mutants. Based on the point mutations, an allele-specific PCR method was developed to detect pyrimorph resistance in P. capsici populations

Paper-based ELISA diagnosis technology for human brucellosis based on a multiepitope fusion protein.

BackgroundBrucellosis, as a serious zoonotic infectious disease, has been recognized as a re-emerging disease in the developing countries worldwide. In china, the incidence of brucellosis is increasing each year, seriously threatening the health of humans as well as animal populations. Despite a quite number of diagnostic methods currently being used for brucellosis, innovative technologies are still needed for its rapid and accurate diagnosis, especially in area where traditional diagnostic is unavailable.Methodology/principal findingsIn this study, a total of 22 B cell linear epitopes were predicted from five Brucella outer membrane proteins (OMPs) using an immunoinformatic approach. These epitopes were then chemically synthesized, and with the method of indirect ELISA (iELISA), each of them displayed a certain degree of capability in identifying human brucellosis positive sera. Subsequently, a fusion protein consisting of the 22 predicted epitopes was prokaryotically expressed and used as diagnostic antigen in a newly established brucellosis testing method, nano-ZnO modified paper-based ELISA (nano-p-ELISA). According to the verifying test using a collection of sera collected from brucellosis and non-brucellosis patients, the sensitivity and specificity of multiepitope based nano-p-ELISA were 92.38% and 98.35% respectively. The positive predictive value was 98.26% and the negative predictive value was 91.67%. The multiepitope based fusion protein also displayed significantly higher specificity than Brucella lipopolysaccharide (LPS) antigen.ConclusionsB cell epitopes are important candidates for serologically testing brucellosis. Multiepitope fusion protein based nano-p-ELISA displayed significantly sensitivity and specificity compared to Brucella LPS antigen. The strategy applied in this study will be helpful to develop rapid and accurate diagnostic method for brucellosis in human as well as animal populations

Level and stability of pyrimorph resistance for the parental wild-type isolates and the resistant mutants of <i>Phytophthora capsici.</i>

a<p>Parent isolates were collected from the field locations. Mutants were obtained by mass selection on pyrimorph-amended medium.</p>b<p>EC₅₀ = effective concentration for 50% inhibition of mycelial growth at the 1^st transfer and the 10^th transfer.</p>c<p>RF = resistance factor, a ratio of EC₅₀ for a fungicide-resistant mutant relative to the EC₅₀ for the parental isolate.</p>d<p>FSC = the ratio of RF values at the 1^st and 10^th transfers.</p

Structure and site of the mutation in the <i>PcCesA3</i> gene associated with pyrimorph resistance.

<p>(A) Intron/exon structure of the <i>PcCesA3</i> gene. Numbers represent the size in base pairs. Point mutations in pyrimorph-resistant mutants (RF>50) and the predicted amino acid substitution in the mutant gene products are indicated. (B) Alignment of partial amino acid sequences of CesA3 in <i>P. capsici</i> (PcCesA3). Hd3, Hd11, Hx18, and Dz21 are wild-type isolates. R3-2, R3-3, and R11-1 are pyrimorph-resistant mutants. Mutations in pyrimorph-resistant mutants of <i>P. capsici</i> are indicated by asterisks.</p

Specificity of allele-specific PCR primers for detection of <i>Phytophthora capsici</i> mutants with high pyrimorph resistance.

<p>R3-2, R3-3, and R11-1 are mutants with high resistance to pyrimorph and were obtained by exposure to the fungicide on agar; isolates Hd3 and Hd11 are the corresponding parental isolates.</p

Concentrations used to determine the sensitivity of wild-type isolates and pyrimorph-resistant mutants of <i>Phytophthora capsici</i> to various fungicides.

a<p>Concentrations used to determine the sensitivity of <i>Phytophthora capsici</i> mutants with high pyrimorph resistance to dimethomorph, flumorph, and mandipropamid respectively.</p

Fitness of pyrimorph-resistant mutants (mutant designations begin with the letter R) and the corresponding parental isolates of <i>Phytophthora capsici</i>^a.

a<p>Means in a column followed by the same letter are not significantly different at <i>p</i> = 0.05 according to Fisher’s least significant difference.</p>b<p>On carrot agar.</p>c<p>Lesion area and sporulation were determined on detached pepper leaves, and disease score was determined on growing pepper plants.</p>d<p>A disease severity scale of 0–5 was used: 0, no visible symptoms; 1, leaves slightly wilted with black lesions beginning to appear on stems or 10–29% of entire plant diseased; 2, 30–49% of entire plant diseased; 3, 50–69% of entire plant diseased; 4, 70–90% of entire plant diseased; 5, dead plant <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056513#pone.0056513-Kim1" target="_blank">[37]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056513#pone.0056513-Hartman1" target="_blank">[38]</a>.</p

Frequency distribution of EC₅₀ values of <i>Phytophthora capsici</i> for pyrimorph.

<p>A total of 226 isolates of <i>P. capsici</i> were collected from 40 locations in 24 provinces of China; the locations had never been treated with pyrimorph. EC₅₀ represents the effective concentration causing 50% inhibition of mycelial growth of <i>P. capsici</i>.</p

Mycelial growth of <i>Phytophthora capsici</i> isolates and mutants on PDA as affected by temperature.

<p>(A, B, C, D) Isolates designated R3-X, R11-X, R18-X, and Dz-X are mutants of Hd3, Hd11, and Hx18, respectively, and were obtained by consecutive transfers on medium amended with pyrimorph. Values are means and standard errors. Colony diameters (minus plug diameters) were measured after 4 days of growth.</p