Arbuscular mycorrhizal fungi activity in the rhizosphere of tree seedlings subjected to residual herbicides / Atividade de fungos micorrízicos arbusculares na rizosfera de mudas de árvores submetidas a herbicidas residuais

Trees occurring on the margins of agricultural areas can mitigate damage from residual herbicides. Rhizospheric microbial activity associated with trees is one of the main remedial capacity indicators. The objective of this study was to evaluate the rhizospheric microbiological activity in tree species subjected to the herbicides atrazine and sulfentrazone via the rhizosphere. The experiment was designed in four blocks and a 6 × 3 factorial scheme. The first factor consisted of six tree species from Brazil and the second of atrazine, sulfentrazone, and water solutions. Four herbicide applications were performed via irrigation. The total dry mass of the plants, mycorrhizal colonization, number of spores, basal respiration of the rhizospheric soil, and survival rate of bioindicator plants after phytoremediation were determined. Trichilia hirta had higher biomass when treated with atrazine and sulfentrazone. Herbicides decreased the microbial activity in Triplaris americana and did not affect the microbiological indicators of Myrsine gardneriana, Schizolobium parahyba, and Toona ciliata. Fewer bioindicator plants survived in soil with Triplaris americana and sulfentrazone. Microbiological indicators were influenced in different ways between species by the presence of herbicides in the rhizosphere.

As árvores que ocorrem nas margens das áreas agrícolas podem mitigar os danos dos herbicidas residuais. A atividade microbiana rizosférica associada às árvores é um dos principais indicadores de capacidade corretiva. O objetivo deste trabalho foi avaliar a atividade microbiológica rizosférica em espécies arbóreas submetidas aos herbicidas atrazina e sulfentrazone via rizosfera. O experimento foi estruturado em quatro blocos e esquema fatorial 6 × 3. O primeiro fator consistiu em seis espécies de árvores do Brasil e o segundo em soluções de atrazine, sulfentrazone e água. Quatro aplicações de herbicidas foram realizadas via irrigação. Foram determinados a massa seca total das plantas, colonização micorrízica, número de esporos, respiração basal do solo rizosférico e taxa de sobrevivência de plantas bioindicadoras após fitorremediação. Trichilia hirta apresentou maior biomassa quando tratada com atrazina e sulfentrazone. Os herbicidas diminuíram a atividade microbiana em Triplaris americana e não afetaram os indicadores microbiológicos de Myrsine gardneriana, Schizolobium parahyba e Toona ciliata. Menos plantas bioindicadoras sobreviveram no solo com Triplaris americana e sulfentrazone. Os indicadores microbiológicos foram influenciados de formas distintas entre as espécies pela presença dos herbicidas na rizosfera.

Exposure to the herbicide atrazine induces oxidative imbalance, morphological damage and decreased survival in juvenile fish

Synthetic herbicides have been intensively used in weed control, although often involved in environmental contamination, critically affecting non-target species. However, never was investigated the effect of commercial formulation using atrazine on developing juvenile fish exposed for 35 days. Juveniles (Astyanax altiparanae) (n = 600) were assigned to the following ATZ-exposed groups: 0 (CTR-control), 0.56 (ATZ0.56), 1.00 (ATZ1.00), 1.66 (ATZ1.66) and 11.66 (ATZ11.66) µg/L. We found a 36.6% decrease in juvenile survival rate in the ATZ11.66 group compared to control and other groups. Juveniles from ATZ11.66 also showed hyperglycemia and increased cortisol levels. Increased the imbalance oxidative with an increase in malondialdehyde (MDA) and Carbonylated proteins levels markers in muscle, gills, and liver. We also found increased activity of the antioxidant enzymes superoxide dismutase (SOD) in gills and SOD and catalase (CAT) in muscles from ATZ11.66 fish, and increased glutathione S-transferase (GST) activities in the liver from all exposed groups compared to control. The morphological consequences of this were loss of secondary lamella integrity, increased mucus-secreting cells, hyperplasia, and lamellar fusion, as well as increased aneurysms percentage. The liver showed vascular congestion associated with endothelial hyperplasia, steatosis, and a decrease in the nuclei percentage. Our results showed that exposure to a commercial formulation of ATZ at 11.66 µg/L can be causing an imbalance in the oxidative markers and morphological damages and decreased survival in a juvenile Neotropical species of great ecological relevance and commercial interest.

Potentiality of Epoxy-Montmorillonite Composite for Stir-Bar Sorptive Extraction for Determination of Atrazine

Abstract A new low-cost material is presented for the first time, aiming to study the sorption process for the stir-bar sorptive extraction (SBSE) technique. The bars were made using a composition of a commercial epoxy resin and montmorillonite, under different compositions and a final ratio of 70% (epoxy) and 30% (montmorillonite) was employed, providing the best mechanical and chemical resistance. A PTFE support was developed to hold the bars permitting the magnetic stirring, without turbulent behavior even under long times of stirring at 1000 rpm. The bars were employed to study the sorption of the herbicide atrazine (ATZ), and the best extraction conditions were: sample volume 20.0 mL, pH 6.0, extraction time of 15 min, room temperature, stirring speed of 100 rpm, and 10.0% (w v-1) NaCl. This preliminary evaluation suggests that the modified bars could be employed for ATZ sorption, affording close to 71% of ATZ removal, and presented robust characteristics to be used at least 80 times.

Effects of weed management and plant arrangements on yield index of sweet sorghum / Eefeito do manejo de plantas daninhas e arranjo de plantas nos índices de produtividade do sorgo sacarino

Sweet sorghum is currently an important alternative for ethanol production in sugar cane off-season. In this study was to evaluate the effects of plant arrangements and the application of atrazine and S-metolachlor on growth and productivity of sweet sorghum. An experiment was conducted in randomized block design and, arranged in split plots with four repetitions. Plots consisted of spacing (0.25 m, 0.45 m 0.45-0.45-0.90 m) and sub-plots of weed control methods - atrazine (2000 g ha-1), atrazine + S-metolachlor (2000 + 720 g ha-1), atrazine + S-metolachlor (2000 + 960 g ha-1), atrazine + S-metolachlor (2000 + 1200 g ha-1), atrazine + S-metolachlor (2000 + 1440 g ha-1). Besides that, manual hoeing control was added. The intoxication of sorghum plants and weed control was evaluated at 7, 14 e 28 days after herbicides application (DAA). Plant height, stem diameter, total fresh matter, juice mass and total soluble solids (°Brix) were evaluated at 120 days after crop emergence (DAE). There was no interaction between the factors spacings and control method for variables total matter fresh (TMF), height (H), stem diameter (D), juice mass (JM), and Brix. Application of the mixture (atrazine + S-metolachlor) in the highest doses reduced total fresh matter and °Brix. The spacing of 0.25 m provided the highest productivity of fresh matter, juice mass and increased the °Brix. The application of mixture (atrazine + S-metolachlor) controlled 90% of the weeds at 28 days after application. The increasing in doses of S-metolachlor elevates the intoxication in sorghum plants. The mixture (atrazine + S-metolachlor) has a potential for use in weed control in sweet sorghum, but at doses below 960 g ha-1 of S-metolachlor.

O objetivo desse trabalho foi avaliar os efeitos de arranjos de plantas e dos herbicidas atrazine e S-metolachlor sobre o crescimento e a produtividade do sorgo sacarino. O experimento foi realizado no delineamento em blocos casualizados, com quatro repetições. Os tratamentos foram dispostos em esquema de parcelas subdivididas. Nas parcelas avaliaram-se os espaçamentos entrelinhas (0,25 m, 0,45 m e 0,45-0,45-0,90 m) e nas subparcelas os métodos de controle das plantas daninhas: atrazine (2000 g ha-1), atrazine + S-metolachlor (2000 + 720 g ha-1), atrazine + S-metolachlor (2000 + 960 g ha-1), atrazine + S-metolachlor (2000 + 1200 g ha-1), atrazine + S-metolachlor (2000 + 1440 g ha-1), capina manual e ausência de controle. Aos 7, 14 e 28 dias após a aplicação dos herbicidas foi avaliado a intoxicação das plantas de sorgo e o nível de controle de plantas daninhas na cultura. Aos 120 dias após a emergência da cultura avaliou-se altura de plantas, diâmetro de colmo, massa fresca total, massa de caldo e o teor de sólidos solúveis totais (Brix). Não houve interação entre os fatores espaçamentos e o método de controle para as variáveis massa fresca total (TMF), altura (H), diâmetro do caule (D), peso do suco (JM) e Brix. O controle das plantas daninhas e a intoxicação visual do sorgo aumentaram linearmente com o incremento das doses do S-metolachlor. O crescimento da cultura e os teores de Brix foram reduzidos pela aplicação da associação entre atrazine + S-metolachlor. A escolha do espaçamento de entrelinha influenciou nos componentes de rendimento da cultura. Conclui-se que, o espaçamento de 0,25 m de entrelinhas proporcionou maior produtividade de matéria fresca e de Brix do caldo. A associação entre atrazine e S-metolachlor tem potencial para o uso no controle de plantas daninhas em sorgo sacarino, em doses abaixo de 960 g ha-1 de S-metolachlor.

Bioremediation of atrazine herbicide contaminated soil using different bioremediation strategies

ABSTRACT: This study evaluated the bioremediation of atrazine herbicide contaminated agricultural soil under different bioremediation strategies using indigenous Pseudomonas aeruginosa, Bacillus subtilis and Aspergillus niger as bioaugmentation agents and poultry droppings as biostimulation agent. The results showed that bioaugmentation with Pseudomonas aeruginosa, bioaugmentation with Bacillus subtilis, bioaugmentation with Aspergillus niger, bioaugmentation with bacterial-fungal consortium (Pseudomonas aeruginosa, Bacillus subtilis and Aspergillus niger), biostimulation with poultry droppings, and combined biougmentation and biostimulation (Pseudomonas aeruginosa, Bacillus subtilis, Aspergillus niger and poultry droppings) resulted in maximum atrazine biodegradation of about 97%, 95%, 84%, 99%, 100% and 100%, respectively. The kinetics of atrazine biodegradation in the soil were modelled using first-order kinetic model and the biodegradation half-life estimated. The first order kinetic model adequately described the kinetics of atrazine biodegradation in soil under the different bioremediation strategies. The rate constants ( k1 ) of atrazine biodegradation in soil subjected to bioaugmentations with Pseudomonas aeruginosa, Bacillus subtilis, Aspergillus niger, and bacterial-fungal consortium ranges between 0.059 day-1 and 0.191 day-1 while for that subjected to natural bioattenuation, biostimulation and combined bioaugmentation and biostimulation are 0.026 day-1, 0.164 day- 1 and 0.279 day-1, respectively. The half-life ( 2 t1/ ) of atrazine biodegradation in soil under natural bioattenuation was obtained to be 26.7 days. This was reduced to between 2.5 and 11.7 days under the application of bioaugmentation, biostimulation and combined bioaugmentation and biostimulation strategies. The bioremediation efficiencies of the different bioremediation strategies in influencing atrazine biodegradation or removal is of the following order: Combined bioaugmentation and biostimulation > Bioaugmentation with bacterial-fungal consortium > Biostimulation with poultry droppings > Bioaugmentation with Pseudomonas aeruginosa > Bioaugmentation with Bacillus subtilis > Bioaugmentation with Aspergillus niger > Natural bioattenuation

High sensitive ELISA for detection of atrazion / 中国应用生理学杂志

OBJECTIVES@#To set up ELISA for detection of atrazine with high precision.@*METHODS@#The reaction condition of indirect-ELISA was optimized, including atrazine-ovalbumin(AT-OVA) concentration and primary antibody concentration, organic solvent, goat anti-rat immunoglobin G-horseradish peroxidase(IgG-HRP) concentration. The actual samples were detected by the ELISA method established in our laboratory. Then the ELISA method was compared with the HPLC.@*RESULTS@#The specification curve of indirect-ELISA was set up after optimization. The relation coefficient R=0.9958. The limit of detection (LOD) was 1.972 ng/ml. The percent recovery of the actual samples was in range of 80%~120%. The ELISA detection sensitivity was higher than the HPLC in the range of 0 ng/ml~6 ng/ml atrazine.@*CONCLUSIONS@#The ELISA to detect atrazine has good specificity and high precision. And it can be applied in testing real atrazine samples replacing of the large-scale instrument.

Controle de plantas de soja e supressão do capim em milho consorciado com Brachiaria ruziziensis / Soybean control and grass suppression in maize with Brachiaria ruziziensis intercropped

O objetivo deste trabalho foi avaliar a melhor dose de atrazina no controle de plantas de soja em meio ao milho safrinha consorciado com Brachiaria ruziziensis (B. ruziziensis), bem como sua interação com diferentes doses de nicosulfuron, de forma a não afetar os benefícios do consórcio. Foram realizados dois bioensaios, o primeiro com seis doses de atrazina (0; 0,6; 0,8; 1,0; 1,2; e 1,4 kgi.a. ha-1). As avaliações foram realizadas 15 e 30 dias após a aplicação (DAA), baseadas na porcentagem de controle das plantas de soja, no número de plantas de B. ruziziensis, no rendimento de grãos de milho e na massa seca do capim. O segundo bioensaio foi conduzido em esquema fatorial 3 (doses de nicosulfuron) × 2 (sem e com atrazina), com duas testemunhas adicionais (testemunha capinada e testemunha sem capina). As doses de nicosulfuron utilizadas foram 2,0; 4,0; e 6,0 gi.a. ha-1, e a dose de atrazina foi de 0,8 kgi.a. ha-1. Doses crescentes de atrazina resultaram em melhor controle das plantas de soja e maior rendimento de grãos de milho. Doses superiores a 1,0 kgi.a. ha-1 de atrazina resultaram em redução na massa seca do capim. A adição de 0,8 kgi.a. ha-1 de atrazina com 2,0; 4,0; ou 6,0 gi.a. ha-1 de nicosulfuron aumentou o controle de plantas de soja em comparação com as doses isoladas de nicosulfuron, não influenciou o número de plantas e a massa seca do capim e proporcionou incremento no rendimento de grãos de milho.(AU)

The aim of this study was to evaluate the best dose of atrazine in soybean control in winter maize intercropped with Brachiaria ruziziensis (B. ruziziensis), as well as its interaction with different doses of nicosulfuron, in a way as not to affect the benefits of farming-pasture integration. Two bioassays were made, the first one with six doses of atrazine (0.0, 0.6, 0.8, 1.0, 1.2, and 1.4 kga.i. ha-1). Evaluations were performed 15 and 30 days after application, based on the percentage of soybean plants control, number of plants of B. ruziziensis, maize grain yield and dry mass of the grass. The second bioassay was conducted in split plot 3 (doses of nicosulfuron) × 2 (with and without atrazine), with two additional witnesses (hand weeded and weeded treatment). Nicosulfuron doses used were 2.0, 4.0 and 6.0 ga.i. ha-1, and atrazine dose used was 0.8 kga.i. ha-1. Increasing doses of atrazine resulted in better soybean plants control and higher maize grain yield. Doses higher than 1.0 kga.i. ha-1 of atrazine resulted in decreased dry mass of the grass. The addition of 0.8 kga.i. ha-1 of atrazine with 2.0, 4.0 and 6.0 ga.i. ha-1 of nicosulfuron increased soybean plants control compared with single doses of nicosulfuron, did not influence the number of plants nor dry mass of the grass and provided increase in maize grain yield.(AU)

Influence of pH, temperature and nutrient addition on the degradation of atrazine by Nocardioides spp. isolated from agricultural soil in Nigeria

Aims: To effectively exploit the atrazine degrading capabilities of Nocardioides spp. isolated from agricultural soil samples in Nigeria and ascertain the effect of pH, temperature and nutrient addition on the degradation process. Methodology and results: Isolates were cultivated on atrazine mineral salts medium at a temperature range of 4 °C - 45 °C and a pH range of 3-10. An optimum atrazine degrading activity was observed in the isolates between temperatures of 25 °C and 37 °C and between pH 5 and 8. Different carbon sources (glycerine, glucose, chitin, cellulose and sodium citrate) and nitrogen sources (urea, biuret, cyanuric acid, potassium nitrate and ammonium chloride) were also added to the medium. The addition of carbon and nitrogen sources did not increase degradation rates although urea and glycerine repressed the degradation ability of the isolates. Statistical analyses of variance at P < 0.05 showed no significant differences in the growth and degradation rates by both bacterial isolates under these conditions. Conclusion, significance and impact study: Atrazine degradation by Nocardioides spp. is pH and temperature dependent, and requires no additional sources of carbon and nitrogen. Hence, its use in bioremediation of atrazine contaminated agricultural soil should be explored.

Response of ligninolytic macrofungi to the herbicide atrazine: dose-response bioassays / Respuesta de macrohongos ligninolíticos al herbicida atrazina: bioensayos dosis-respuesta

The effect of atrazine concentrations on mycelial growth and ligninolytic enzyme activities of eight native ligninolytic macrofungi isolated in Veracruz, México, were evaluated in a semi-solid culture medium. Inhibition of mycelial growth and growth rates were significantly affected (p = 0.05) by atrazine concentrations (468, 937, 1875, and 3750 mg/l). In accordance with the median effective concentration (EC50), Pleurotus sp. strain 1 proved to be the most tolerant isolate to atrazine (EC50 = 2281.0 mg/l), although its enzyme activity was not the highest. Pycnoporus sanguineus strain 2, Daedalea elegans and Trametes maxima showed high laccase activity (62.7, 31.9, 29.3 U mg/protein, respectively) without atrazine (control); however, this activity significantly increased (p < 0.05) (to 191.1, 83.5 and 120.6 U mg/protein, respectively) owing to the effect of atrazine (937 mg/l) in the culture medium. Pleurotus sp. strain 2 and Cymatoderma elegans significantly increased (p < 0.05) their manganese peroxidase (MnP) activities under atrazine stress at 468 mg/l. The isolates with high EC50 (Pleurotus sp. strain 1) and high enzymatic activity (P. sanguineus strain 2 and T. maxima) could be considered for future studies on atrazine mycodegradation. Furthermore, this study confirms that atrazine can increase laccase and MnP activities in ligninolytic macrofungi.

Se evaluó el efecto de diferentes concentraciones de atrazina sobre el crecimiento micelial y la actividad enzimática de ocho macrohongos ligninolíticos aislados en Veracruz, México. La inhibición del crecimiento micelial y la tasa de crecimiento diaria fueron significativamente (p < 0,05) afectadas por todas las dosis de atrazina (468, 937, 1875 y 3750 mg/l) adicionadas al medio de cultivo. De acuerdo con la concentración efectiva media (CE50), Pleurotus sp. cepa 1 fue el aislamiento más tolerante a la atrazina (CE50 = 2281 mg/l), aunque sus actividades enzimáticas no fueron altas. Pycnoporus sanguineus cepa 2, Daedalea elegans y Trametes maxima mostraron actividades altas de lacasa (62,7, 31,9 y 29,3 U mg/proteína, respectivamente) en ausencia de atrazina (control); estas actividades se incrementaron (p < 0,05) significativamente (191,1, 83,5 y 120,6 U mg/proteína, respectivamente) en presencia de atrazina (937 mg/l) en el medio de cultivo. Pleurotus sp. cepa 2 y Cymatoderma elegans incrementaron significativamente (p < 0,05) sus actividades de manganeso peroxidasa (MnP) bajo la concentración de 468 mg/l de atrazina. Los aislamientos con alta CE50 (Pleurotus sp. cepa 1) y alta actividad enzimática (P. sanguineus cepa 2 y T. maxima) podrían ser considerados para futuros estudios en la micodegradación de atrazina. Además, el presente estudio confirma que la atrazina puede incrementar las actividades lacasa y MnP en macrohongos ligninolíticos.

Toxic effects of atrazine on reproductive system of male rats / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>This study was designed to evaluate the toxic effects of Atrazine (ATZ) on the reproductive system of male rats.</p><p><b>METHODS</b>Male Sprague-Dawley rats were exposed to ATZ by gavage at dosages of 0, 38.5, 77, and 154 mg/kg bw/day for 30 d. The toxic effects of ATZ to rats were assessed through histopathologcal observation, spermatozoa quality evaluation, testicular marker enzyme indicators, antioxidant capacity and reproductive hormone levels.</p><p><b>RESULTS</b>Significant adverse effects on reproductive system were observed in rats exposed to ATZ at different dosages compared with 0 mg/kg group, including an irregular and disordered arrangement of the seminiferous epithelium in 154 mg/kg group; a decreased spermatozoa number and an increased spermatozoa abnormality rate in 77 and 154 mg/kg groups; decreased levels of acid phosphatase (ACP), alkaline phosphatase (AKP), lactic dehydrogenase (LDH), and succinate dehydrogenase (SDH) with the increasing of ATZ concentration; a decreased level of total antioxidant capacity (TAC) in a dose-dependent manner, and a decreased reduced glutathione (GSH) level and an increased malondialdehyde (MDA) content in 154 mg/kg group; and decreased serum levels of testosterone (T) and inhibin-B (INH-B) and an increased serum level of follicle stimulating hormone (FSH) in 77 and 154 mg/kg groups, and an increased serum level of luteinizing hormone (LH) in 154 mg/kg group.</p><p><b>CONCLUSION</b>These results suggested that relatively high doses of ATZ could exert reproductive toxicity of male rats.</p>

Seleção de espécies bioindicadoras para uso em bioensaios de lixiviação e persistência de Atrazina no solo / Selection of bioindicators for use on leaching and persistence of Atrazine in soil bioassays

Este experimento teve por objetivo selecionar espécies cultivadas com potencial para utilização como bioindicadoras da presença de atrazina em ensaios de persistência e lixiviação. Adotou-se delineamento inteiramente casualizado, com quatro repetições, em bifatorial 5 x 6, sendo o fator A constituído pelas concentrações de atrazina com formulação WG (0, 150, 300, 600, 1200 g atrazina ha-1) e o fator B pelas espécies bioindicadoras: aveia branca, trigo, quiabo, tomate, ervilha e rabanete. Aplicou-se o herbicida atrazina em pré-emergência das espécies em solo argiloso. Realizaram-se quatro avaliações de estatura de planta, injúria e no fi nal do experimento foram determinadas as matérias verde e seca das partes aéreas. De forma geral, o experimento permitiu classifi car as espécies conforme seu nível de sensibilidade à atrazina: quiabo e ervilha evidenciaram pequena sensibilidade; aveia e trigo revelaram nível intermediário de sensibilidade, enquanto que o tomate e o rabanete apresentaram o mais alto nível de sensibilidade.

High throughput screening atrazine chlorohydrolase mutants with enhanced activity through Haematococcus pluvialis expression system / 生物工程学报

Developing a high-throughput screening method is of great importance for directed evolution of atrazine chlorohydrolase. A mutagenesis library of atzA from Pseudomonas sp. ADP and Arthrobacter sp. AD1 was constructed using error-prone PCR and DNA shuffling. Candidate mutants were screened through Haematococcus pluvialis expression system, using atrazine as selection pressure. Sequence analysis showed that mutations in the obtained 12 mutants with enhanced activity were all point-substitutions and scattered throughout the gene. Enzymatic activity analysis showed that the mutants all had higher activities than that of the wild type. The activities were 1.8-3.6 fold of the wild-type enzyme when cultured in BBM medium with 1 mg/L atrazine, whereas 1.8-2.6 fold with 2 mg/L atrazine. These results indicated that Haematococcus pluvialis expression system is an ideal high throughput screening system for directed evolution of atrazine chlorohydrolase.

Presence of atrazine in the biological samples of cattle and its consequence adversity in human health

Cattle can be considered as an important source for herbicides through nutrition. Therefore, herbicide residue in animal products is a potential human exposure to herbicides causing public health problems in human life. Triazines are a group of herbicides primarily used to control broadleaf weeds in corn and other feed ingredients and are considered as possible human carcinogens. To evaluate trace residue of these pollutants molecular imprinted solid phase extraction [MISPE] method has been developed, using biological samples. Blood samples were taken from the jugular vein of 45 Holstein cows in 3 commercial dairy farms in Khuzestan Province, Iran. Urine samples were also taken from the cows. The mean +/- SD concentrations of atrazine in serum and urine samples of the study group [0.739 +/- 0.567 ppm and 1.389 +/- 0.633 ppm, respectively] were higher [P < 0.05] than the concentrations in serum and urine samples of the control group [0.002 +/- 0.005 ppm and 0.012 +/- 0.026 ppm, respectively]. Atrazine in the feed ingredients ingested by cattle could be transferred into the biological samples and consequently can be considered as a potential hazard for the public health

Avaliação da intoxicação aguda induzida por atrazina em espécie da ictiofauna do pantanal mato-grossense, pacu (Piaractus mesopotamicus), com o emprego de biomarcadores morfológicos / Morphological biomarkers for assessing acute toxicity of atrazine in pacu (Piaractus mesopotamicus) fingerlings, a freshwater species from the Brazilian pantanal wetland

Atrazina é um herbicida muito usado em agricultura intensiva e encontrado com alta freqüência em recursos hídricos na região do Pantanal Mato-grossense. Assim, devido aos riscos que a atrazina pode trazer à ictiofauna da região, foi proposta deste trabalho determinar a CL50 da atrazina em alevinos de pacu (Piaractus mesopotamicus). A determinação da CL50 em 96 h em sistema estático, realizada em duplicata, foi conduzida em aquários de vidro com 8 peixes cada, de peso médio de 5,06±0,31g, avaliando-se as seguintes concentrações nominais de atrazina: 0; 13,2; 17,6; 22,0; 26,4; 30,8; 35,2; 39,6 mg L-1, realizando-se também análise comportamental e análise anatomopatológica. Experimento de intoxicação aguda foi realizado em duplicata, nas mesmas condições do anterior, com a concentração da CL50 obtida (28,58 mg L-1), sendo empregados 6 exemplares de peso médio 6,68±0,36g. Amostras hepáticas e mesonéfricas foram colhidas e processadas para análise de microscopia de luz (ML), realizando-se nestas amostras análise semi-quantitativa das alterações encontradas, e para análise de microscopia eletrônica de transmissão (MET). Quanto à avaliação comportamental, foram observados nos grupos tratados: o escurecimento da pigmentação da pele, várias alterações na intensidade do movimento, perda de equilíbrio e presença da ação de boquejamento. Na avaliação anatomopatológica, foram observadas nos grupos tratados: dilatação da região ventral, exoftalmia, protrusão labial, hiperemia no opérculo e em todas as nadadeiras, presença de ar e/ou água no estômago e ascite sanguinolenta...

Exposure to atrazine caused darkening of the skin, alterations in the intensity of movements, loss of balance and an increase in the frequency of gasping. Anatomopathological assessment revealed dilation of the ventral region, exophthalmia, lip protrusion, skin hyperemia in the opercular region and in all fins, the presence of air and/or water in the stomach, and bloody ascites after the herbicide exposition. The histopathological analysis revealed the typical hepatic and renal morphology for the specie, in control group. Several histopathological changes were observed in exposed fish, but the changes most significant were: in liver, the presence of hyaline inclusions in the cytoplasm of hepatocytes, and proximal tubule (PT) degeneration in the kidney. The ultrastructure showed that the atrazine caused several membrane alterations suggestive of oxidative stress and lipid peroxidation...

Fuzzy rule based estimation of agricultural diffuse pollution concentration in streams.

Outflow from the agricultural fields carries diffuse pollutants like nutrients, pesticides, herbicides etc. and transports the pollutants into the nearby streams. It is a matter of serious concern for water managers and environmental researchers. The application of chemicals in the agricultural fields, and transport of these chemicals into streams are uncertain that cause complexity in reliable stream quality predictions. The chemical characteristics of applied chemical, percentage of area under the chemical application etc. are some of the main inputs that cause pollution concentration as output in streams. Each of these inputs and outputs may contain measurement errors. Fuzzy rule based model based on fuzzy sets suits to address uncertainties in inputs by incorporating overlapping membership functions for each of inputs even for limited data availability situations. In this study, the property of fuzzy sets to address the uncertainty in input-output relationship is utilized to obtain the estimate of concentrations of a herbicide, atrazine, in a stream. The data of White river basin, a part of the Mississippi river system, is used for developing the fuzzy rule based models. The performance of the developed methodology is found encouraging.

Molecular imprinted solid phase extraction for determination of atrazine in environmental samples

Solid phase extraction is one of the major applications of molecularly imprinted polymers fields for clean-up of environmental and biological samples namely molecularly imprinted solid-phase extraction. In this study, solid phase extraction using the imprinted polymer has been optimized with the experimental design approach for a triazine herbicide, named atrazine with regard to the critical factors which influence the molecular imprinted solid phase extraction efficiency such as sample pH, concentration, flow-rate, volume, elution solvent, washing solvent and sorbent mass. Optimization methods that involve changing one factor at a time can be laborious. A novel approach for the optimization of imprinted solid-phase extraction using chemometrics is described. The factors were evaluated statistically and also validated with spiked water samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. Also, in order to the evaluate efficiency of the optimized molecularly imprinted solid-phase extraction protocols, enrichment capacity, reusability and cross-reactivity of cartridges have been also evaluated. Finally, selective molecularly imprinted solid-phase extraction of atrazine was successfully demonstrated with a recovery above 90% for spiked drinking water samples. It was concluded that the chemometrics is frequently employed for analytical method optimization and based on the obtained results, it is believed that the central composite design could prove beneficial for aiding the molecularly imprinted polymer and molecularly imprinted solid-phase extraction development

Potencial de contaminação da água subterrânea por pesticidas na bacia do rio Dourados, MS / The potential of contamination of groundwater by pesticides in Dourados river watershed, MS- Brazil

Este trabalho teve os seguintes objetivos: 1) elaborar base de dados contendo informações sobre o uso de pesticidas na Bacia Hidrográfica do Rio Dourados (BHRD) na Bacia Hidrográfica do Rio Dourados (BHRD), MS; 2) simular a lixiviação dos principais pesticidas utilizados na BHRD por meio do simulador PEARL; e 3) gerar "ranking" dos principais pesticidas utilizados na BHRD com relação ao seu potencial de contaminação das águas subterrâneas. A base de dados foi composta por 4.374 receituários agronômicos emitidos no ano de 2002. Os dados de entrada para o simulador PEARL foram determinados experimentalmente ou obtidos na literatura. As simulações foram realizadas considerando o período de 19 anos, obtendo-se as concentrações na fase líquida do solo a 2, 5 e 10 m de profundidade e profundidades máximas de lixiviação. Os pesticidas mais usados na BHRD foram o glifosato, seguido em ordem decrescente pelo 2,4-D, fipronil, metamidofós, imazaquim, parationa metílica, trifluralina e atrazina. As simulações revelaram que os pesticidas com maior potencial de contaminação da água subterrânea na BHRD foram o bentazona, imazetapir, fomesafem, 2,4-D, metamidofós, imazaquim, tiodicarbe e monocrotofós.

The effect of the glyphosate, 2,4-D, atrazine e nicosulfuron herbicides upon the Edaphic collembola (Arthropoda: Ellipura) in a no tillage system

The use of herbicides is a common and intensive practice in no tillage systems. The herbicides can influence, directly or indirectly, the population of edaphic arthropods. Collembola is a group that functions as a bio-indicator of soil conditions. The degree of abundance and diversity of Collembola provides the level of soil disturbance provoked by agricultural practices. This experiment was designed to compare the influence of herbicides on the population fluctuation of Collembola in a no-till soil preparation system. The work was conducted in a non irrigated no-till area at the Núcleo Experimental de Ciências Agrárias of the Universidade Federal de Mato Grosso do Sul (UFMS), Campus de Dourados, in soil planted with corn as a surface covering, during the period of December, 2002 to December, 2003. The data were analyzed according to a completely randomized model, in a split plot design. The plots received four types of herbicides: glyphosate, atrazine, 2,4-D and nicosulfuron. A fifth plot did not receive any herbicide (control), for a total of five treatment types. The sub plots were represented by their collection times (10, 20, 30 and 40 days after the herbicide applications). Both the type of herbicide and the time of data sampling influenced the Collembola population fluctuaction. The treatments with atrazine and 2,4-D caused the most reduction of the population of Collembola, depending on the time of application.

No plantio direto o uso de herbicidas é uma prática comum e intensiva, que influencia direta ou indiretamente a população de artrópodes da mesofauna edáfica. O grau de abundância e diversidade de Collembola comumente é indicado para comprovar a extensão de distúrbios de várias práticas agrícolas, pois esse grupo serve como bioindicador das condições do solo. Esta pesquisa teve como objetivo comparar a influência de alguns herbicidas na flutuação populacional de Collembola, em solo sob o sistema de plantio direto. O trabalho foi realizado em uma área de plantio direto de sequeiro, do Núcleo Experimental de Ciências Agrárias da Universidade Federal de Mato Grosso do Sul (UFMS), Campus de Dourados, em latossolo roxo distroférrico com cobertura de milho, durante os meses de outubro de 2002 a janeiro de 2003. Os dados obtidos foram analisados segundo o modelo inteiramente casualizado constituído de tratamentos dispostos no esquema de parcelas subdivididas, onde as parcelas são representadas por uma testemunha mais quatro herbicidas: glifosate, atrazina, 2,4-D e nicosulfuron (totalizando cinco tratamentos) e as subparcelas pelas épocas de cada coleta (10, 20, 30 e 40 dias após aplicação dos herbicidas). Tanto os herbicidas testados quanto as épocas de coleta influenciaram a população de Collembola. Dependente do período de degradação dos herbicidas no solo, os tratamentos com 2,4-D, Atrazina, foram os que mais influenciaram a abundância de Collembola reduzindo sua população.

The establishment of hypospadias rat model and embryoteratogenic test of Atrazine / 中华整形外科杂志

<p><b>OBJECTIVE</b>To establish an easily reproducible animal model of hypospadias and to test whether Atrazine can induce hypospadias in animal experiment.</p><p><b>METHODS</b>From the 11th to 16th day after conception, 120 conceived SD rats were divided randomly into 6 groups: one coin oil group (1 ml/kg/d), two finasteride groups (10 mg/kg/d, 20 mg/kg/d), three Atrazine groups (25 mg/kg/d, 100 mg/kg/d, 200 mg/kg/d). When all pregnant rats had delivered, the new born rats were counted and the penis appearance, urethral orifice position and micturition were observed with magnifying lens and anatomy microscope.</p><p><b>RESULTS</b>Hypospadias were found in new born male rats treated prenatally with Finasteride (10 mg/kg/d, 20 mg/kg/d) and 200 mg/kg/d Atrazine groups. The incidence was 28.30%, 67.03%, 10.23% respectively. Embryotoxic effects were observed at 25 mg/kg/d Atrazine group in 2 rats and associated with no severe maternal toxicity.</p><p><b>CONCLUSIONS</b>(1) A hypospadias SD rats model can be established by Finasteride and it is easily reproducible. (2) The Atrazine was teratogenic to the SD rats, embryotoxic effects were observed at the low dose level and associated with no severe maternal toxicity.</p>

Study on the atrazine-degrading genes in Arthrobacter sp. AG1 / 生物工程学报

Atrazine could be used as the sole carbon, nitrogen and energy sources for growth by strain Arthrobacter sp. AG1, and the atrazine-degrading genes of AG1 were found to be the combination of trzN, atzB and atzC. The atrazine chloride hydrolysase gene trzN was cloned by PCR amplification,whose sequence shared 99% identity with that of Norcardioides sp. C190. Two large plasmids were found in AG1,and trzN and atzB were confirmed to be localized on the larger plasmid pAG1 by the method of southern hybridization. Subculture of AG1 in liquid LB for three generations, 34% of the subsequent cells were found to lose degrading activity, however, neither plasmid was lost. PCR amplification results showed that the mutants had only lost the trzN gene instead of atzB and atzC. It was deduced that mutation might be due to the trzN gene deletion from the plasmid. This study provided new evidence that atrazine metabolic genotypes were resulted from horizontal gene transfer between different bacteria under environmental selective pressure.