RESUMO
This work assessed the impact of fuelling an automotive engine with palm biodiesel (pure, and two blends of 10% and 20% with diesel, B100, B10 and B20, respectively) operating under representative urban driving conditions on 17 priority polycyclic aromatic hydrocarbon (PAH) compounds, oxidative potential of ascorbic acid (OPAA), and ecotoxicity through Daphnia pulex mortality test. PM diluted with filtered fresh air (WD) gathered in a minitunel, and particulate matter (PM) collected directly from the exhaust gas stream (W/oD) were used for comparison. Results showed that PM collecting method significantly impact PAH concentration. Although all PAH appeared in both, WD and W/oD, higher concentrations were obtained in the last case. Increasing biodiesel concentration in the fuel blend decreased all PAH compounds, and those with 3 and 5 aromatic rings were the most abundant. Palm biodiesel affected both OPAA and ecotoxicity. While B10 and B20 exhibited the same rate of ascorbic acid (AA) depletion, B100 showed significant faster oxidation rate during the first four minutes and oxidized 10% more AA at the end of the test. B100 and B20 were significantly more ecotoxic than B10. The lethal concentration LC50 for B10 was 6.13 mg/L. It was concluded that palm biodiesel decreased PAH compounds, but increased the oxidative potential and ecotoxicity.
Assuntos
Poluentes Atmosféricos , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/toxicidade , Biocombustíveis/análise , Biocombustíveis/toxicidade , Gasolina/análise , Gasolina/toxicidade , Estresse Oxidativo , Óleo de Palmeira , Material Particulado/análise , Material Particulado/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Emissões de Veículos/análise , Emissões de Veículos/toxicidadeRESUMO
Cladocerans are constantly exposed to humic substances in nature, yet the effects of these substances on their survival and reproduction are not well known. Here, the effects of humic substances (20 and 40 mg L-1) (HS) on the life history variables of three common cladocerans, Ceriodaphnia dubia, Moina macrocopa, and Daphnia pulex were evaluated. The results showed that the effect of humic substances on the tested cladocerans is species-specific, affecting either survival, reproduction or both. For M. macrocopa, exposed to HS at a concentration of 40 mg L-1, the average lifespan and the life expectancy at birth were significantly reduced as compared to controls, but for C. dubia and D. pulex these parameters were increased. Gross reproductive rate was unaffected by the HS level for both D. pulex and M. macrocopa, but it was significantly higher for C. dubia. When compared to the corresponding controls, for HS-exposed cladocerans, the rate of population increase was significantly reduced in case of D. pulex while it was stimulated for both C. dubia and M. macrocopa. It appears that humic substances had a slightly stronger influence on survivorship than on reproduction of the tested cladocerans.
Assuntos
Cladocera/efeitos dos fármacos , Substâncias Húmicas/efeitos adversos , Reprodução/efeitos dos fármacos , Animais , Cladocera/fisiologia , Daphnia/efeitos dos fármacos , Demografia , Feminino , Substâncias Húmicas/análise , Masculino , Especificidade da EspécieRESUMO
Inducible, anti-predator traits are a classic example of phenotypic plasticity. Their evolutionary dynamics depend on their genetic basis, the historical pattern of predation risk that populations have experienced and current selection gradients. When populations experience predators with contrasting hunting strategies and size preferences, theory suggests contrasting micro-evolutionary responses to selection. Daphnia pulex is an ideal species to explore the micro-evolutionary response of anti-predator traits because they face heterogeneous predation regimes, sometimes experiencing only invertebrate midge predators and other times experiencing vertebrate fish and invertebrate midge predators. We explored plausible patterns of adaptive evolution of a predator-induced morphological reaction norm. We combined estimates of selection gradients that characterize the various habitats that D. pulex experiences with detail on the quantitative genetic architecture of inducible morphological defences. Our data reveal a fine scale description of daphnid defensive reaction norms, and a strong covariance between the sensitivity to cues and the maximum response to cues. By analysing the response of the reaction norm to plausible, predator-specific selection gradients, we show how in the context of this covariance, micro-evolution may be more uniform than predicted from size-selective predation theory. Our results show how covariance between the sensitivity to cues and the maximum response to cues for morphological defence can shape the evolutionary trajectory of predator-induced defences in D. pulex.
Assuntos
Daphnia/genética , Comportamento Predatório , Animais , Ecossistema , Peixes , Cadeia Alimentar , FenótipoRESUMO
Activity-guided fractionation of the methanol extract of Daphnia pulex. (Leydig) using the MTT assay and P-388, A549, KB, and HT-29 cell lines permitted the isolation of four known glyceroglycolipid compounds: (2S.)-1-O.-(7Z.,10Z.,13Z.)-hexadecatrienoyl-2-O.-(7Z.,10Z.)-hexadecadienoyl-3-O.-ß.-D-galactopyranosyl-sn.-glycerol, (2S.)-1-O.-(7Z.,10Z.)-hexadecadienoyl-2-O.-(7Z.,10Z.)-hexadecadienoyl-3-O.-ß.-D-galactopyranosyl-sn.-glycerol, (2S.)-1-O.-(7Z.,10Z.)-hexadecadienolyl-2-O.-linolenoyl-3-O.-ß.-D-galactopyranosyl-sn.-glycerol, and (2S.)-1-O.-(9Z., 12Z.)-octadecadienoyl-2-O.-(7Z.,10Z.)-hexadecadienoyl-3-O.-(α.-D-galactopyranosyl(1-6)-ß.-D-galactopyranosyl-sn.-glycerol. All the isolates were found to be moderately cytotoxic (ED50 < 4 µg/ml) toward P-388, A549, KB, and HT-29 cell lines.