Triclocarban: UV photolysis, wastewater disinfection, and ecotoxicity assessment using molecular biomarkers.

Triclocarban (TCC) is an antibacterial agent found in pharmaceuticals and personal care products (PPCP). It is potentially bioaccumulative and an endocrine disruptor, being classified as a contaminant of emerging concern (CEC). In normal uses, approximately 96% of the used TCC can be washed down the drain going into the sewer system and eventually enter in the aquatic environment. UV photolysis can be used to photodegrade TCC and ecotoxicity assays could indicate the photodegradation efficiency, since the enormous structural diversity of photoproducts and their low concentrations do not always allow to identify and quantify them. In this work, the TCC was efficiently degraded by UVC direct photolysis and the ecotoxicity of the UV-treated mixtures was investigated. Bioassays indicates that Daphnia similis (48 h EC50 = 0.044 µM) was more sensitive to TCC than Pseudokirchneriella subcapitata (72 h IC50 = 1.01 µM). TCC and its photoproducts caused significant effects on Eisenia andrei biochemical responses (catalase and glutathione-S-transferase); 48 h was a critical exposure time, since GST reached the highest activity values. UVC reduced the TCC toxic effect after 120 min. Furthermore, TCC was photodegraded in domestic wastewater which was simultaneously disinfected for total coliform bacterial (TCB) (360 min) and Escherichia coli (60 min). Graphical abstract TCC degradation and ecotoxicological assessment.

Modulation of oxidative responses by a virulent isolate of Colletotrichum fructicola in apple leaves.

Apple bitter rot (ABR) and Glomerella leaf spot (GLS) can be caused by Colletotrichum fructicola. Although both diseases can occur simultaneously in orchards, some isolates show clear organ specialization. Thus, this work was aimed to compare microscopically the development of preinfective structures of ABR- and GLS isolates and their impact on the enzymatic oxidant defense system during the leaf infection process. On leaves, conidial germlings of GLS-isolate formed appressoria mostly sessile. In contrast, those of ABR-isolate were pedicellate and formed multiple melanized appressoria probably as a sign of unsuccessful infection attempts. Neither ABR- nor GLS isolate triggered hypersensitive response in apple leaves. In overall, the activity of scavenging enzymes was higher and long-lasting in leaves inoculated by GLS- than by ABR isolate and control. Guaiacol peroxidase, catalase, and glutathione reductase had activity peaks within 24 h after inoculation (HAI). Ascorbate peroxidase activity was higher only in GLS-infected leaves at 6 HAI, while superoxide dismutase remained unaltered. A lower level of hydrogen peroxide (H2O2) was determined in GLS-infected plants at 48 HAI, but the electrolyte leakage markedly increased. Disease symptoms in leaves were only caused by GLS-isolate. Results suggest that the virulent isolate coordinately downregulates the oxidative plant defense responses enabling its successful establishment in apple leaves.

Insecticides induced biochemical changes in freshwater microalga Chlamydomonas mexicana.

The effect of insecticides (acephate and imidacloprid) on a freshwater microalga Chlamydomonas mexicana was investigated with respect to photosynthetic pigments, carbohydrate and protein contents, fatty acids composition and induction of stress indicators including proline, superoxide dismutase (SOD) and catalase (CAT). C. mexicana was cultivated with 1, 5, 10, 15, 20 and 25 mg L(-1) of acephate and imidacloprid. The microalga growth increased with increasing concentrations of both insecticides up to 15 mg L(-1), beyond which the growth declined compared to control condition (without insecticides). C. mexicana cultivated with 15 mg L(-1) of both insecticides for 12 days was used for further analysis. The accumulation of photosynthetic pigments (chlorophyll and carotenoids), carbohydrates and protein was decreased in the presence of both insecticides. Acephate and imidacloprid induced the activities of superoxide dismutase (SOD) and catalase (CAT) and increased the concentration of proline in the microalga, which play a defensive role against various environmental stresses. Fatty acid analysis revealed that the fraction of polyunsaturated fatty acids decreased on exposure to both insecticides. C. mexicana also promoted 25 and 21% removal of acephate and imidacloprid, respectively. The biochemical changes in C. mexicana on exposure to acephate and imidacloprid indicate that the microalga undergoes an adaptive change in response to the insecticide-induced oxidative stress.

Heavy metal accumulation and biochemical evaluation of earthworms from sawmills in Abeokuta, South-Western Nigeria

Over the years, sawmilling industries have shown a high growth in the rain forest areas of Nigeria, releasing several wastes into the environment. This study aims at using earthworms (Eudrilus eugeniae, Libyodrilus violaceous and Hyperiodrilus africanus) of sawmill origin as bio-indicators of metal pollution in sawmills. Four major sawmills located in Abeokuta (7°9'11"44" N - 3°19'35" E), namely Lafenwa, Sapon, Isale-Ake and Kotopo sawmills were used for this study. The arboretum of the Federal University of Agriculture, Abeokuta was used as control site. Earthworms, plant and soil samples were collected each month for three months (March to May, 2013), randomly from different points at each of the locations. Protein analysis was conducted on the earthworms using gel electrophoresis while the activities of Superoxide dismutase (SOD), Catalase (CAT) and Glutathione peroxidase (GPx) were done spectrophotometrically. Heavy metal analysis was also conducted on soil, plant and earthworm samples using Atomic Absorption Spectrophotometer. Gel electro-phoresis results revealed the presence of nine protein bands in E. eugeniae from Sapon and Kotopo sawmills, as compared to six protein bands of E. eugeniae from the control site. Seven protein bands were observed in L. violaceous from Lafenwa and H. africanus from Isale-Ake sawmills. Levels of SOD, GPx and CAT activities were significantly higher (P < 0.05) in E. eugeniae from Sapon sawmill than those of Kotopo sawmill and the control site. This study also revealed that Pb and Cd concentrations were higher in the earthworms, plants and soil from the sawmills than those of the control site. Sapon sawmill recorded significantly higher (P < 0.05) levels of Cd and Cu in plants as well as Pb and Cd in soil samples than those of the other locations. The concentrations of Cu, Co and Ni were higher in the soil of the control site than in the sawmill soils. Stronger relationship exists in the metal concentrations between the earthworms and soils (R= 0.602) than between the plants and soil (R= 0.405). Sawmilling therefore posses potential risks on sawmill soil and soil fauna, especially earthworm species.

A través de los años, la industria de aserraderos ha mostrado un alto crecimiento en las áreas de bosque tropical de Nigeria, lanzando varios residuos al ambiente. Este estudio tiene como objetivo utilizar lombrices (Eudrilus eugeniae, Libyodrilus violaceous y Hyperiodrilus africanus) de origen aserradero como bioindicadores de contaminación por metales en los aserraderos. Se utilizaron cuatro grandes aserraderos ubicados en Abeokuta (7°9'11"44" N - 3°19'35" E), a saber: Lafenwa, Sapon, Isale-Ake y Kotopo, para este estudio. El arboreto de la Universidad Federal de Agricultura, Abeo-kuta fue utilizado como sitio de control. Las lombrices de tierra, plantas y muestras de suelo se recogieron cada mes durante tres meses (marzo a mayo 2013), al azar en diferentes puntos en cada una de las localidades. El análisis de proteínas se llevó a cabo en las lombrices de tierra utilizando electroforesis en gel, mientras que las actividades de la superóxido dismutasa (SOD), catalasa (CAT) y glutatión peroxidasa (GPx) se realizaron espectrofotométricamente. Análisis de metales pesados también se llevaron a cabo en muestras de suelo, plantas y lombrices de tierra utilizando espectrofotómetro de absorción atómica. Resultados de la electroforesis del gel reveló la presencia de nueve bandas de proteínas de E. eugeniae en los aserraderos de Sapon y Kotopo, en comparación con seis bandas de proteínas de E. eugeniae de el sitio control. Se observaron siete bandas de proteínas de L. violaceous de Lafenwa y H. africanus en los aserraderos Isale-Ake. Los niveles de SOD, GPx y actividades CAT fueron significativamente mayores (P <0.05) en E. eugeniae del aserradero Sapon que las del aserradero Kotopo y el sitio control. El estudio también reveló que las concentraciones de Pb y Cd fueron mayores en las lombrices de tierra, plantas y el suelo de los aserraderos que los del sitio control. El aserradero Sapon mostró niveles significativamente mayores (P <0.05) de Cd y Cu en las plantas, así como Pb y Cd en muestras de suelo que las de los otros lugares. Las concentraciones de Cu, Co y Ni fueron mayores en el suelo del sitio de control que en los suelos de los aserraderos. Existe relación más fuerte en las concentraciones de metales entre las lombrices de tierra y los suelos (R = 0.602) que entre las plantas y el suelo (R = 0.405). Por lo tanto, la actividad en los aserraderos posee riesgos potenciales en el suelo y su fauna, especialmente las especies de lombrices.