SaRCC1, a Regulator of Chromosome Condensation 1 (RCC1) Family Protein Gene from Spartina alterniflora, Negatively Regulates Salinity Stress Tolerance in Transgenic Arabidopsis.

A regulator of chromosome condensation 1 (RCC1) family protein has been functionally characterized to be involved in various cellular processes. In this study, one RCC1 gene named SaRCC1 was cloned from the full-length cDNA library of Spartinaalterniflora. The open reading frame (ORF) of SaRCC1 was 1440 bp, and it encoded 479 amino acids with a calculated molecular mass of 51.65 kDa. Multiple amino acid sequence alignments showed that SaRCC1 had high identity with other plant RCC1s, and the phylogenetic analysis indicated that SaRCC1 had a closer affinity to Zea mays RCC1 family protein (ZmRCC1). SaRCC1 gene was induced under salt stress conditions, and its encoded protein was located in peroxisome. In order to further investigate the function of SaRCC1, transgenic Arabidopsis plants ectopically both sense-overexpressing and antisense-overexpressing SaRCC1 were generated. SaRCC1-overexpressing lines exhibited an increased salt and ABA hypersensitivity and reduced resistance to salinity stress. On the other hand, the transcripts of some stress-responsive genes in the SaRCC1 transgenic plants were affected in response to salinity stress. Our results provide evidence for the involvement of SaRCC1, negatively regulating salt stress responses by affecting stress-related gene expression in Arabidopsis.

Bioaccumulation and toxicity effects of flubendiamide in zebrafish (Danio rerio).

Flubendiamide is a widely used diamide insecticide with many adverse effects on environmental organisms. This study assessed its bioaccumulation and toxicity effects in zebrafish (Danio rerio) using LC-MS/MS. The concentrations of flubendiamide in the whole zebrafish increased in the early stages and achieved steady levels at 14 days. The bioconcentration factors (BCFs) of flubendiamide was 1.125-2.011. Although flubendiamide did not significantly affect the growth phenotypes of zebrafish, it significantly changed the hepatic somatic index (HSI) of zebrafish. Histopathological analysis showed that flubendiamide could cause structural damage to the liver tissue of zebrafish. Further physiological and biochemical analysis showed that flubendiamide significantly changed the activity of catalase (CAT) and the contents of malondialdehyde (MDA) and glutathione (GSH) in liver of zebrafish. Moreover, flubendiamide significantly changed the mRNA expression levels of cell apoptosis-related genes, including p53, puma, caspase-3, caspase-9, apaf-1, and bax in liver of zebrafish. In summary, these results indicate that flubendiamide can cause liver damage by inducing oxidative stress and apoptosis in the liver of zebrafish. This study provides a background for further safety evaluation of flubendiamide to aquatic organisms.

Adsorption and Desorption Behaviors of Spirotetramat in Various Soils and Its Interaction Mechanism.

Spirotetramat is a pesticide with bidirectional systemicity and can effectively control pests by inhibiting the biosynthesis of fatty acids. In this study, adsorption and desorption behaviors of spirotetramat in six soils and its interaction mechanism were studied using the batch equilibrium method and infrared radiation. The results showed that the adsorption and desorption behaviors of spirotetramat conformed to the Freundlich isotherm model. The values of adsorption capacities KF-ads ranged from 2.11 to 12.40, and the values of desorption capacities KF-des varied from 2.97 to 32.90. From the hysteresis coefficient, spirotetramat was easily desorbed from the test soils. The adsorption capacity of the soil to spirotetramat enhanced with an increasing temperature. Moreover, the changes in pH values and exogenous addition of humic acid and surfactant could also affect soil adsorption capacity, but for desorption, there was no correlation.

Dissipation kinetics and risk assessments of tricyclazole during Oryza sativa L. growing, processing and storage.

Because of the increase of people's attention to food safety, monitoring the residue of pesticide in rice is becoming more and more important. Commercial and home processing techniques have been used to transform paddy rice into rice products for human or animal consumption, which may reduce the pesticide content in rice. The degradation of tricyclazole during different stages of commercial and home processing and storage was assessed in this paper. Many researches studying the occurrence and distribution of pesticide residues during rice cropping and processing have been reported. Rice samples were extracted with acetonitrile, the extracts were enriched, and then residues were analyzed by liquid chromatography/tandem mass spectrometry method. The dissipation dynamics of tricyclazole in rice plant, soil, and paddy water fitted the first-order kinetic equations. The dissipation half-lives of tricyclazole in the rice plant, water, and soil at dosage of 300~450 g a.i. hm -2 were 4.84~5.16, 4.64~4.85, and 3.57~3.82 days, respectively. The residue levels of tricyclazole gradually reduced with different processing procedures. What is more, decladding process could effectively remove the residues of tricyclazole in raw rice, and washing process could further remove the residues of tricyclazole in polished rice. Degradation dynamic equations of tricyclazole in the raw rice and polished rice were based on the first-order reaction dynamic equations, and the half-lives of the degradation of tricyclazole was 43.32~58.24 days and 46.83~56.35 days in raw rice and polished rice. These results provide information regarding the fate of tricyclazole in the rice food chain, while it provides a theoretical basis for systematic evaluation of the potential residual risk of tricyclazole.

Environmental behaviors of spirotetramat in water.

Spirotetramat is a pesticide with bidirectional systemicity in both xylem and phloem. Currently, researches show that spirotetramat has definite toxicity to aquatic organism. This paper aims to study the environmental behaviors of spirotetramat in water, in the hope of providing guidance for security evaluation of spirotetramat. The researches in this paper showed that under lighting condition, the half-life period of spirotetramat in water was 13.59 days. In water, spirotetramat could be degraded into B-enol and B-keto. As seen from the residual concentrations of two products, B-enol was the dominant degradation product. Under different temperatures, the hydrolysis products of spirotetramat remain B-enol and B-keto. The temperature has little effect on the residual concentration of spirotetramat in water. The residual concentration of B-enol in water gradually increased with the extension of time but B-keto had no significant change. In the buffer solution of different pH values, the degradation rate of spirotetramat was significantly enhanced with the increase of solution pH value. The hydrolysis products of spirotetramat in buffer solution of different pH values were still B-enol and B-keto, and pH exerted certain influence on the residual concentration of B-enol in water. The hydrolysis conversion of spirotetramat has theoretical and practical significance for the safe and reasonable usage of it, as well as for the further evaluation of spirotetramat's ecological risk in water.

Determination and Safety Assessment of Residual Spirotetramat and Its Metabolites in Amaranth (Amaranthus tricolor) and Soil by Liquid Chromatography Triple-Quadrupole Tandem Mass Spectrometry.

With the purpose of guaranteeing the safe use of spirotetramat and preventing its potential health threats to consumers, a QuEChERS extraction method coupled with LC triple-quadrupole tandem MS was applied in this study to determine residual spirotetramat metabolites in different tissues of amaranth (Amaranthus tricolor) and in soil. The results indicate that the spirotetramat degraded into different types of metabolites that were located in different tissues of amaranth and in soil. B-keto, B-glu, and B-enol were the three most representative degradation products in the leaf of amaranth, and B-glu and B-enol were the two major degradation products found in the stem of amaranth; however, only B-enol was detected in the root of amaranth. B-keto and B-mono were the two products detected in the soil in which the amaranth grew. The cytotoxicity results demonstrate that spirotetramat and its metabolite B-enol inhibited cellular growth, and the toxicity of spirotetramat and its metabolite B-enol exceeded than that of the metabolites B-keto, B-mono, and B-glu. This investigation is of great significance to the safe use of spirotetramat in agriculture.