Catalase in fluvial biofilms: a comparison between different extraction methods and example of application in a metal-polluted river

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore, been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase extraction from fluvial biofilms. Homogenization followed by glass bead disruption appeared to be the best compromise for catalase extraction. This method was then applied to a field study in a metal-polluted stream (Riou Mort, France). The most polluted sites were characterized by a catalase activity 4–6 times lower than in the low-polluted site. Results of the comparison process and its application are promising for the use of catalase activity as an early warning biomarker of toxicity using biofilms in the laboratory and in the field

Persistent organic pollutants in two reservoirs along the Paraíba do Sul-Guandu River system, Rio de Janeiro, Brazil

Sediment contamination is evaluated by determining organic micropollutants (organochlorine compounds - OCs and polycyclic aromatic hydrocarbons - PAHs) in two important Brazilian water reservoirs. Trace levels of OCs were observed in the Santana reservoir (44.8 ng g-1 d.w. of p,p'-DDT), while in the Funil reservoir the levels were below detection level. Forty-eight percent of the found sigmaocs were polychlorinated biphenyls, 29% dichlorodiphenyltrichloroethane (DDT), 18% Drins, and 5% other pesticides (HCB, Heptachlor, Heptachlor-epoxide, gamma-HCH and a-Endosulfan). We observed lower levels of sigmaPAH in the Funil reservoir (1 to 275 ng g-1d.w.) than in the Santana reservoir (2.2 to 26.7 µg g-1 d.w.).

Pharmaceuticals occurrence in a WWTP with significant industrial contribution and its input into the river system

Occurrence and removal of 81 representative Pharmaceutical Active Compounds (PhACs) were assessed in a municipal WWTP located in a highly industrialized area, with partial water reuse after UV tertiary treatment and discharge to a Mediterranean river. Water monitoring was performed in an integrated way at different points in the WWTP and river along three seasons. Consistent differences between therapeutic classes were observed in terms of influent concentration, removal efficiencies and seasonal variation. Conventional (primary and secondary) treatment was unable to completely remove numerous compounds and UV-based tertiary treatment played a complementary role for some of them. Industrial activity influence was highlighted in terms of PhACs presence and seasonal distribution. Even if global WWTP effluent impact on the studied river appeared to be minor, PhACs resulted widespread pollutants in river waters. Contamination can be particularly critical in summer in water scarcity areas, when water flow decreases considerably

Blocking and unblocking in a navigation task

Rodrigo, Chamizo, McLaren, & Mackintosh (1997) demonstrated the blocking effect in a navigational task using a swimming pool: rats initially trained to use three landmarks (ABC) to find an invisible platform learned less about a fourth landmark (X) added later than did rats trained from the outset with these four landmarks (ABCX). The aim of the experiment reported here was to demonstrate unblocking using a similar procedure as in the previous work. Three groups of rats were initially trained to find an invisible platfom in the presence of three landmarks: ABC for the Blocking and Unblocking groups and LMN for the Control group. Then, all animals were trained to find the platform in the presence of four landmarks, ABCX. In this second training, unlike animals in the Blocking group to which only a new landmark (X) was added in comparison to the first training, the animals in the Unblocking group also had a change in the platform position. In the Control group, both the four landmarks and the platform position were totally new at the beginning of this second training. As in Rodrigo et al. (1997) a blocking effect was found: rats in the Blocking group learned less with respect to the added landmark (X) than did animals in the Control group. However, rats in the Unblocking group learned about the added landmark (X) as well as did animals in the Control group. The results are interpreted as an unblocking effect due to a change in the platform position between the two phases of training, similarly to what is normal in classical conditioning experiments, in which a change in the conditions of reinforcement between the two training phases of a blocking design produce an attenuation or elimination of this effect. These results are explained within an error-correcting connectionist account of spatial navigation (McLaren, 2002).

River Conservation: Going against the Flow to Meet Global Challenges

Rivers are among the most diverse and threatened ecosystems on Earth, as they are impacted by increasing human pressures. Because rivers provide essential goods and services, conservation of these ecosystems is a requisite for sustainable development. Therefore, we must seek ways to conserve healthy rivers and to restore degraded ones

Organochlorine pesticides in Piracicaba river basin (São Paulo/Brazil): a survey of sediment, bivalve and fish

The main objective of this paper was to evaluate the level of occurrence of the organochlorine compounds in samples of sediments, bivalves and two fish species collected in the Piracicaba River basin (São Paulo, Brazil). The isomers alpha and gamma of HCH and Heptachlor were most frequently detected in samples of sediments and specimens of bivalve and fish. Therefore, although the levels of these compounds found were not critically high, they are still found in the environment. This fact suggests that they are still being used, despite the fact that the use of these compounds was outlawed more than twenty years ago.

Remoção de Pb2+ e Cr3+ em solução por zeólitas naturais associadas a rochas eruptivas da formação serra geral, bacia sedimentar do Paraná

The capacity of natural zeolites and its host rock (dacite) to remove Pb2+ and Cr3+ from aqueous solutions has been investigated. Results showed that both samples prefer to remove Pb2+ instead of Cr3+. Almost 100% of Pb2+ was removed from solutions with concentration until 50 mg L-1 and 100 mg L-1 of this metal, respectively by dacite and zeolite. The equilibrium of metals adsorption process was reached during the first 30 min by both materials. Na+ can be used to recover Pb2+, but not to remove Cr3+ from the treated samples. The Sips model showed a good fit for experimental data of this study.

Aplicação de redes neurais artificiais na identificação de gasolinas adulteradas comercializadas na região de Londrina - Paraná

The multilayer perceptron network was used to classify the gasoline. The main parameters used in the classification were established by the Ordinance nº 309 of the Agência Nacional do Petróleo, but without informing the network the legal limits of these parameters. The network used had 10 neurons in a single hidden layer, learning rate of 0.04 and 250 training epochs. The application of artificial neural network served classify 100% of the commercialized gas in the region of Londrina-PR and to identify the tampered gasoline even those suspected of tampering.

Chumbo e zinco em águas e sedimentos de área de mineração e metalurgia de metais

Lead metallurgy at Adrianópolis is the largest environmental problem of Paraná, Brazil. The objective of this study was to determine Pb and Zn levels in water and sediment in two catchments by different extraction methods. The high levels of lead in water in most of samples do not allow the human use. Total Pb concentration as high as 795.3 µg L-1 was observed in Ribeira River bank, in a pluvial water stream flowering from a abandoned factory. Due to the high Pb levels in sediments from some sites (maximum of 24,300 mg kg-1) is recommended to avoid the water turbulence.

Ocorrência de doenças do pak choi no estado do Paraná, Brasil

A cultura do pak choi (Brassica chinensis), hortaliça de origem Asiática, foi introduzida no Brasil há dois anos por empresas importadoras de sementes. No estado do Paraná vem se destacando na região de Curitiba, principalmente em condições de cultivo protegido. Realizou-se um levantamento da ocorrência de doenças na cultura na safra 1999/2000. Os experimentos foram conduzidos na Fazenda Escola "Capão da Onça" da Universidade Estadual de Ponta Grossa (UEPG), com a diagnose das doenças sendo realizada nos laboratórios de fitopatologia da UEPG e da ESALQ/USP. As doenças que apresentaram maior intensidade na safra de verão foram a Mancha de Alternaria (Alternaria sp.), a Podridão Mole (Erwinia sp.) e a Ferrugem Branca (Albugo candida). Na safra de outono, a Mancha de Alternaria e a Podridão Mole apresentaram baixa incidência e não se observou a ocorrência de Ferrugem Branca.

Análise molecular de segmento do RNA2 de comovirus isolados de soja no estado do Paraná

Nas áreas produtoras de feijão (Phaseolus vulgaris) do Estado do Paraná observa-se anualmente a ocorrência do vírus do mosaico em desenho do feijoeiro (Bean rugose mosaic virus, BRMV), principalmente em infecções mistas com o vírus do mosaico dourado do feijoeiro (Bean golden mosaic virus, BGMV), acarretando maior severidade de sintomas e causando perdas na produção. Recentemente constatou-se a presença do vírus do mosaico severo do caupi (Cowpea severe mosaic virus, CPSMV) associado a sintomas de queima do broto em plantações de soja (Glycine max) na região de Londrina, sendo este um fato novo no Estado. Neste trabalho, parte do RNA2 de dois comovirus isolados de soja no Paraná foram clonados e sequenciados, sendo 600 pares de bases (pb) do BRMV-PR e 594 pb do CPSMV-PR. Posteriormente, as seqüências correspondentes de aminoácidos foram comparadas com seis seqüências de vírus do gênero Comovirus depositadas no GenBank. Com base nestes dados observou-se que o segmento do RNA2 do isolado CPSMV-PR apresentou homologia de 85% com parte de uma seqüência já conhecida do RNA2 do CPSMV, enquanto que o segmento do RNA2 do isolado BRMV-PR apresentou homologia de 39% com o CPSMV, e de 44% com o Bean pod mottle virus (BPMV). Este trabalho apresenta pela primeira vez dados de sequenciamento parcial do BRMV, o que poderá contribuir para sua completa caracterização molecular e para o estabelecimento de estratégias para obtenção de plantas resistentes ao vírus.

Levantamento de fungos associados às podridões do colmo e quantificação de danos em lavouras de milho do Planalto Médio gaúcho e dos Campos Gerais do Paraná

Os danos causados pelas podridões da base do colmo, a incidência de colmos doentes e as espécies de fungos envolvidas foram determinados em amostragem procedida em 29 lavouras de milho (Zea mays) destinadas à produção de grãos e de sementes, localizadas nas regiões do Planalto Médio gaúcho (RS) e dos Campos Gerais do Paraná (PR), nas safras 1997/98 e 1998/99. Os danos na safra 1997/98 variaram de 213 a 3.089 com média de 678 e na safra 1998/99 de 358 a 3.086 com média de 1.151 kg.ha-1. A incidência de colmos doentes no primeiro ano variou de 11,2 a 71,4 com média de 40,9 e no segundo de 21,9 a 79,3 com média de 45,9%. Não foi observada correlação entre os danos e a incidência de colmos doentes provavelmente pela diversidade das lavouras quanto aos fatores como genótipos, sistema de cultivo e forma de semeadura, fertilidade do solo, adubação e condições ambientais. A espécie de fungo que apresentou a maior incidência na primeira safra foi Colletotrichum graminicola e, na segunda, Fusarium graminearum. Além dessas, identificou-se outras espécies, como Diplodia maydis, D. macrospora, Fusarium moniliforme e F. subglutinans.

Primeiro relato da podridão da estipe da pupunheira, causada por Phytophthora palmivora, no estado do Paraná

Phytophthora palmivora foi isolado de plantas de pupunheira (Bactris gasipaes) com sintomas de podridão da estipe, no Paraná, em 2002. Testes de patogenicidade e o subseqüente reisolamento do fungo confirmaram a hipótese de que P. palmivora é o agente causal da podridão do estipe. Este é o primeiro relato de P. palmivora causando podridão do estipe na pupunheira no estado do Paraná.