RESUMO
The acute and chronic toxicity of bisphenol A (BPA) was evaluated on the common South American toad Rhinella arenarum embryos and larvae by means of continuous and pulse exposure treatments. Embryos were treated continuously from early blastula (S.4) up to complete operculum (S.25), during early larval stages and by means of 24 h pulse exposures of BPA in concentrations ranging between 1.25 and 40 mg L(-1) , in order to evaluate the susceptibility to this compound in different developmental stages. For lethal effects, S.25 was the most sensitive and gastrula was the most resistant to BPA. The Teratogenic Index for neurula, the most sensitive embryonic stage for sublethal effects was 4.7. The main morphological alterations during early stages were: delayed or arrested development, reduced body size, persistent yolk plug, microcephaly, axial/tail flexures, edemas, blisters, waving fin, underdeveloped gills, mouth malformations, and cellular dissociation. BPA caused a remarkable narcotic effect from gill circulation stage (S.20) onwards in all the organisms exposed after 3 h of treatment with 10 mg L(-1) BPA. After recovering, the embryos exhibited scarce response to stimuli, erratic or circular swimming, and spasmodic contractions from 5 mg L(-1) onwards. Our results highlight the lethal and sublethal effectsof BPA on R. arenarum embryos and larvae, in the last case both at structural and functional levels.
Assuntos
Compostos Benzidrílicos/toxicidade , Bufonidae/anormalidades , Fenóis/toxicidade , Teratogênicos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Tamanho Corporal/efeitos dos fármacos , Embrião não Mamífero/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Brânquias/anormalidades , Brânquias/efeitos dos fármacos , Larva/efeitos dos fármacos , Dose Letal Mediana , Anormalidades da Boca/induzido quimicamente , Estupor/induzido quimicamenteRESUMO
Biotic descriptors--both taxonomic (diversity indices, species richness, and indicator species) and nontaxonomic (biomass, oxygen consumption/production, and anatomical deformities)--are useful tools for measuring a stream's ecological condition. Nontaxonomic parameters detect critical effects not reflected taxonomically. We analyzed changes in Chironomidae populations as taxonomic parameters and mentum deformities as a nontaxonomic parameter for evaluating a South-American-plains stream (Argentina). We performed samplings seasonally (March, June, September, and December; 2005) and physical and chemical measurements at three sampling sites of the stream (DC1 at river source, through DC3 downstream). The specimens collected in sediment and vegetation were analyzed to investigate mouth deformities in Chironomidae larvae. We identified a total of 9 taxa from Chironomidae and Orthocladiinae subfamilies. Shannon's diversity index for Chironomidae decreased from 1.6 bits ind⻹ (DC1) to 0.3 bits ind⻹ (DC3). The total density of the Chironomidae exhibited a great increase in abundance at site DC3, especially that of Chironomus calligraphus. Chironomidae taxonomic composition also changed among the three sites despite their spatial proximity: C. calligraphus, Goeldichironomus holoprasinus, Parachironomus longistilus, and Polypedilum were present at all three; Corynoneura and Paratanytarsu at DC1 only; Cricotopus at DC1 and DC3; Apedilum elachistus notably at DC2 and DC3; and Parametriocnemus only at DC2. C. calligraphus individuals from DC1 showed no mentum deformities; only 2 from DC2 exhibited mouth-structure alterations; while specimens from DC3 presented the most abnormalities, especially during autumn and late winter. Type-II deformities (supernumerary teeth and gaps) were the most common. Anatomical deformities are sublethal effects representing an early alert to chemically caused environmental degradation. Mentum deformities in benthic-Chironomidae larvae constitute an effective biological-surveillance tool for detecting adverse conditions in sediments and evaluating sediment-quality-criteria compliance. Taxonomic (community composition) and nontaxonomic (condition of larval mouth parts) descriptors, used together, can indicate a stream's ecological state.
Assuntos
Biodiversidade , Chironomidae/classificação , Monitoramento Ambiental/métodos , Rios/química , Animais , Argentina , Chironomidae/efeitos dos fármacos , Chironomidae/crescimento & desenvolvimento , Cidades , Ecossistema , Larva/classificação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Anormalidades da Boca/induzido quimicamente , Filogenia , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
The Chironomidae (Diptera: Insecta) have a high species richness, with species adapted to live under widely different environmental conditions. The study of the taxonomic composition of chironomid larvae and the percentage of occurrence of deformities in mouthparts, mainly in the mentum, are used in biomonitoring programmes in order to obtain information on the levels of organic and chemical pollution of aquatic ecosystems. The objective of this study was to evaluate the abundance of chironomid larvae and to quantify the occurrence of mentum deformities in the specimens collected in three urban reservoirs with different trophic levels. The reservoirs are located in the hydrographic basin of the Paraopeba River, an affluent of the São Francisco River basin (Minas Gerais State, southeastern Brazil). The Serra Azul Reservoir is oligotrophic, the Vargem das Flores Reservoir is mesotrophic, and the Ibirité Reservoir is eutrophic. Along the littoral zone of each reservoir, 30 samples were collected during each sampling campaign. Sampling was carried out every three months for one year, with two sampling campaigns during the wet season and two during the dry season in 2008. Physical and chemical parameters measured in the water column included the water depth, Secchi depth, air and water temperature, electrical conductivity, total dissolved solids, redox potential, dissolved oxygen, pH, turbidity, Total-N, Total-P, P-ortho, and chlorophyll-a. The chironomid larvae were identified to the genus level. The structure of the chironomid assemblages was evaluated based on taxonomic richness (24 genera), density, equitability, and diversity. The potential indicator taxa for each reservoir were established through an Indicator Species Analysis. The values for taxonomic richness (20 taxa), equitability (0.737), and Shannon-Wiener diversity (2.215) were highest in the Serra Azul Reservoir. Fissimentum was the indicator taxon in Serra Azul, the oligotrophic reservoir; whereas Pelomus was the indicator taxon in Vargem das Flores, and Chironomus in Ibirité. The highest percentage of mentum deformities was found during the dry season in Serra Azul (6.9%), while the lowest percentage was found during the wet season in Vargem das Flores (0.8%). The results of this study evidenced significant differences in the taxonomic composition, richness, equitability, and diversity of the chironomid assemblages in these three reservoirs of different trophic levels.
Assuntos
Biodiversidade , Chironomidae/classificação , Monitoramento Ambiental/métodos , Água Doce/análise , Animais , Brasil , Chironomidae/efeitos dos fármacos , Chironomidae/crescimento & desenvolvimento , Larva/classificação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Anormalidades da Boca/induzido quimicamente , Densidade Demográfica , Estações do Ano , População UrbanaRESUMO
The Chironomidae (Diptera: Insecta) have a high species richness, with species adapted to live under widely different environmental conditions. The study of the taxonomic composition of chironomid larvae and the percentage of occurrence of deformities in mouthparts, mainly in the mentum, are used in biomonitoring programmes in order to obtain information on the levels of organic and chemical pollution of aquatic ecosystems. The objective of this study was to evaluate the abundance of chironomid larvae and to quantify the occurrence of mentum deformities in the specimens collected in three urban reservoirs with different trophic levels. The reservoirs are located in the hydrographic basin of the Paraopeba River, an affluent of the São Francisco River basin (Minas Gerais State, southeastern Brazil). The Serra Azul Reservoir is oligotrophic, the Vargem das Flores Reservoir is mesotrophic, and the Ibirité Reservoir is eutrophic. Along the littoral zone of each reservoir, 30 samples were collected during each sampling campaign. Sampling was carried out every three months for one year, with two sampling campaigns during the wet season and two during the dry season in 2008. Physical and chemical parameters measured in the water column included the water depth, Secchi depth, air and water temperature, electrical conductivity, total dissolved solids, redox potential, dissolved oxygen, pH, turbidity, Total-N, Total-P, P-ortho, and chlorophyll-a. The chironomid larvae were identified to the genus level. The structure of the chironomid assemblages was evaluated based on taxonomic richness (24 genera), density, equitability, and diversity. The potential indicator taxa for each reservoir were established through an Indicator Species Analysis. The values for taxonomic richness (20 taxa), equitability (0.737), and Shannon-Wiener diversity (2.215) were highest in the Serra Azul Reservoir. Fissimentum was the indicator taxon in Serra Azul, the oligotrophic reservoir; whereas Pelomus was the indicator taxon in Vargem das Flores, and Chironomus in Ibirité. The highest percentage of mentum deformities was found during the dry season in Serra Azul (6.9 percent), while the lowest percentage was found during the wet season in Vargem das Flores (0.8 percent). The results of this study evidenced significant differences in the taxonomic composition, richness, equitability, and diversity of the chironomid assemblages in these three reservoirs of different trophic levels.
Os Chironomidae (Diptera-Insecta) apresentam ampla riqueza de espécies e adaptam-se a diferentes condições ambientais. O estudo da composição taxonômica de larvas de Chironomidae e o percentual de ocorrência de deformidades encontrado em peças do aparelho bucal, principalmente no mento, são utilizados em programas de biomonitoramento para obter informações a respeito do nível de poluição orgânica e química em ecossistemas aquáticos. O objetivo deste estudo foi avaliar a abundância e quantificar a ocorrência de deformidades no mento de larvas de Chironomidae coletadas em três reservatórios urbanos em diferentes estados tróficos na bacia hidrográfica do rio Paraopeba, afluente da bacia do rio São Francisco (MG). O estudo foi desenvolvido nos reservatórios de Serra Azul (oligotrófico), Vargem das Flores (mesotrófico) e Ibirité (eutrófico). Foram coletadas 30 amostras na região litorânea de cada reservatório, ao longo de todo perímetro, trimestralmente, ao longo de um ano (duas coletas na estação seca e duas na chuvosa). Algumas variáveis físicas e químicas (profundidade, Secchi, temperatura do ar e da água, condutividade elétrica, sólidos totais dissolvidos, potencial oxi-redox, oxigênio dissolvido, pH, turbidez, N-total, P-total, P-orto e clorofila-a) foram mensuradas na coluna d'água. As larvas de Chironomidae foram identificadas até o nível de gênero. A estrutura das assembleias de Chironomidae foi avaliada com base na riqueza taxonômica (24 gêneros), densidade, equitabilidade e diversidade. Foram estimados os táxons indicadores em cada reservatório através de uma análise de espécies indicadoras. Os valores de riqueza taxonômica (20 táxons), equitabilidade (0,737) e diversidade de Shannon-Wiener (2,215) foram maiores em Serra Azul do que nos outros reservatórios. Fissimentum foi o táxon indicador no reservatório de Serra Azul, Pelomus no reservatório de Vargem das Flores e Chironomus no reservatório de Ibirité. O maior percentual de deformidades no mento das larvas foi encontrado no reservatório de Serra Azul na estação seca (6,9 por cento), enquanto o menor percentual foi reportado no reservatório de Vargem das Flores na estação chuvosa (0,8 por cento). Os resultados deste estudo evidenciaram diferenças significativas entre a composição taxonômica, riqueza, equitabilidade e diversidade nos três reservatórios em diferentes níveis tróficos, corroborando o papel das larvas de Chironomidae como bioindicadoras.
Assuntos
Animais , Biodiversidade , Chironomidae/classificação , Monitoramento Ambiental/métodos , Água Doce/análise , Brasil , Chironomidae/efeitos dos fármacos , Chironomidae/crescimento & desenvolvimento , Larva/classificação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Anormalidades da Boca/induzido quimicamente , Densidade Demográfica , Estações do Ano , População UrbanaRESUMO
El objetivo del presente trabajo fue caracterizar morfológica, morfométrica y estereológicamente las alteraciones del piso de la boca de fetos de rata, provocadas por el ácido retinoico cuando es administrado en el 10º día de preñez. Los resultados obtenidos sugieren que el ácido retinoico actúa en la embriogénesis provocando alteraciones del desarrollo embrionario
Assuntos
Animais , Feminino , Gravidez , Ratos , Soalho Bucal , Ratos Wistar , Tretinoína , Anormalidades da Boca/induzido quimicamente , Anormalidades Induzidas por Medicamentos , Desenvolvimento Fetal , Cariometria , Soalho Bucal , Ratos Wistar , TretinoínaRESUMO
El objetivo fue caracterizar morfólogica, morfométrica y estereológicamente los cambios epiteliales del paladar, en fetos de rata cuyas madres tratadas con una única dosis intraperitoneal de 2,5 mg de plomo/100 g de peso corporal. Se utilizaron 5 fetos de ratas para el grupo control y 5 para el grupo tratado, recogidos en el vigésimo día de preñez. Los fetos fueron fijados durante 24 horas en una solución compuesta de 85 ml de etanol (85 por ciento), 10 ml de formol y 5 ml de ácido acético y, posteriormente, pesados e incluídos en parafina. Los cortes histológicos semiseriados de 6 µm de espesor fueron teñidos con hematoxilina-eosina. Además del análisis histopatológico, el epitelio palatino fue medido a través de técnicas morfométricas y estereológicas. Los resultado sugieren que el plomo actuaría sobre la embriogénesis alterando el desarrollo embrionario, resultando fetos pequeños y menos desarrollados. Fueron demostradas alteraciones en el peso de la placenta y en la longitud del cordón umbilical. Estos resultados, comparados con la literatura, justifican el menor peso fetal. Los resultados mostraron también, que tanto el epitelio del paladar blando, como del palador duro eran más finos con células menos voluminosas y alargadas