RESUMEN
The housefly (Musca domestica L.) lives in close association with its microbiota and its symbionts are suggested to have pivotal roles in processes such as metabolism and immune response, but it is unclear how the profound physiological changes during ontogeny affect the housefly's associated microbiota and their metabolic capabilities. The present study applies 16S rRNA gene amplicon sequencing to investigate the development of the host-associated microbiota during ontogeny. The potential for microbiota transfer between developmental stages, and the metabolic potential of these microbiota were evaluated. Representatives of Firmicutes were observed as early colonisers during the larval stages, followed by colonisation by organisms affiliating with Proteobacteria and Bacteroidetes as the flies matured into adults. Microbiota observed across all the developmental stages included Lactococcus, Lactobacillus and Enterococcus, while Weissella and Chishuiella were associated with newly hatched larvae and adults, respectively. Predictive metabolic profiling of the identified microorganisms further suggested that the microbiota and their functional profile mature alongside their host and putative host-microbe relationships are established at different stages of development. The predicted metabolic capability of the microbiota developed from primarily simple processes including carbohydrate and nucleotide metabolisms, to more complex metabolic pathways including amino acid metabolisms and processes related to signal transduction.
Asunto(s)
Moscas Domésticas/crecimiento & desarrollo , Moscas Domésticas/microbiología , Estadios del Ciclo de Vida , Microbiota , Animales , Femenino , Moscas Domésticas/fisiología , Intestinos/microbiología , Masculino , Microbiota/genética , ARN Ribosómico 16S/genética , Caracteres Sexuales , SimbiosisRESUMEN
Fluoxetine and propranolol are neuroactive human pharmaceuticals that occur frequently as pollutants in surface waters. The potential effects of these pharmaceuticals on aquatic organisms have raised concern but many adverse effects are not well characterized for a broad range of concentrations and endpoints. In this study, 6 biological parameters in the freshwater Cladoceran Daphnia magna were compared for their responses to fluoxetine or propranolol exposure: mobility (dichotomous response), active swimming time, swimming distance, swimming velocity, swimming acceleration speed, and survival in the absence of food (starvation-survival). Changes in swimming behavior was quantified by video tracking followed by image analyses at six exposure concentrations between 100â¯ng/L and 10â¯mg/L. Active swimming time and swimming distance were the most responsive parameters among the behavioral traits. Sublethal exposure concentrations resulted in nonmonotonic responses and behavior profiling suggested that fluoxetine and propranolol stimulated swimming activity at 1-10⯵g/L whereas lower (0.1-1⯵g/L) and higher exposure concentrations (>100⯵g/L) inhibited swimming activity. The ability to survive in the absence of food when exposed to fluoxetine or propranolol resulted in EC50 and EC10 values that were lower than for swimming behavior (EC50 of 0.79-0.99â¯mg/L; EC10 of 1.4-2.9⯵g/L). Starvation-survival appeared to be a potentially simple and sensitive endpoint for adverse effects in D. magna at intermediate exposure concentrations. Nonmonotonic behavioral responses at low exposure concentrations and decreased ability to survive starvation should be considered in assessment of adverse effects of pharmaceuticals to freshwater invertebrates.
Asunto(s)
Conducta Animal/efectos de los fármacos , Daphnia/efectos de los fármacos , Fluoxetina/efectos adversos , Propranolol/efectos adversos , Contaminantes Químicos del Agua/farmacología , AnimalesRESUMEN
Aquatic pollutants are often biologically active at low concentrations and impact on biota in combination with other abiotic stressors. Traditional toxicity tests may not detect these effects, and there is a need for sensitive high-throughput methods for detecting sublethal effects. We have evaluated an automated infra-red (IR) light-based monitor for recording the swimming activity of Daphnia magna to establish temporal patterns of toxicant effects on an individual level. Activity was recorded for 48 h and the sensitivity of the monitor was evaluated by exposing D. magna to the reference chemicals K2 Cr2 O7 at 15, 20 and 25 °C and 2,4-dichlorophenol at 20 °C. Significant effects (P < 0.001) of toxicant concentrations, exposure time and incubation temperatures were observed. At 15 °C, the swimming activity remained unchanged for 48 h at sublethal concentrations of K2 Cr2 O7 whereas activity at 20 and 25 °C was more biphasic with decreases in activity occurring after 12-18 h. A similar biphasic pattern was observed after 2,4-dichlorophenol exposure at 20 °C. EC50 values for 2,4-dichlorophenol and K2 Cr2 O7 determined from automated recording of swimming activity showed increasing toxicity with time corresponding to decreases in EC50 of 0.03-0.07 mg l(-1) h(-1) . EC50 values determined after 48 h were comparable or lower than EC50 values based on visual inspection according to ISO 6341. The results demonstrated that the swimming activity monitor is capable of detecting sublethal behavioural effects that are toxicant and temperature dependent. The method allows EC values to be established at different time points and can serve as a high-throughput screening tool in toxicity testing. Copyright © 2015 John Wiley & Sons, Ltd.