Developmental pruning of sensory neurites by mechanical tearing in Drosophila.

Mechanical forces actively shape cells during development, but little is known about their roles during neuronal morphogenesis. Developmental neurite pruning, a critical circuit specification mechanism, often involves neurite abscission at predetermined sites by unknown mechanisms. Pruning of Drosophila sensory neuron dendrites during metamorphosis is triggered by the hormone ecdysone, which induces local disassembly of the dendritic cytoskeleton. Subsequently, dendrites are severed at positions close to the soma by an unknown mechanism. We found that ecdysone signaling causes the dendrites to become mechanically fragile. Severing occurs during periods of increased pupal morphogenetic tissue movements, which exert mechanical forces on the destabilized dendrites. Tissue movements and dendrite severing peak during pupal ecdysis, a period of strong abdominal contractions, and abolishing ecdysis causes non-cell autonomous dendrite pruning defects. Thus, our data establish mechanical tearing as a novel mechanism during neurite pruning.

Sediment contamination and toxic effects on Violet Goby fish (Gobioides broussonnetii - Gobiidae) from a marine protected area in South Atlantic.

The Estuarine-Lagoon Complex of Iguape-Cananéia (ELCIC), a Marine Protected Area (MPA) in Brazil, was the focus of this study that aimed to relate external levels of exposure to contaminants to toxic effects on Gobioides broussonnetii fish. Different anthropogenic contaminants such as metals, polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals and personal care products (PPCPs) were analyzed in the sediments; and biochemical, histopathological and genotoxicity biomarkers evaluated in fish; in two different seasons at three sites of the estuarine region. Higher contamination of the sediments was observed near the main urban center (Iguape city - IG). Metal concentrations were considered low to moderate, while PAHs concentrations were considered low. The concentrations of PPCPs increased due to the anthropogenic presence and were higher near IG and the Cananéia Island (CI). Contributions from historical mining, agriculture, nautical activities, oil, sewage and waste disposal, biomass and fossil fuels combustion were identified. Higher concentrations of metals and PPCPs were observed during the cold-dry season, suggesting influences of the lower hydrodynamics during the season of lower precipitation. Higher PAHs concentrations occurred in the hot-rainy season, indicating influences of greater human presence in summer. In fish, biological responses followed the same spatial and seasonal pattern. More pronounced changes in antioxidant, biotransformation, histopathological and genotoxic biomarkers were observed in IG and CI. The multivariate analysis and the integrated biomarkers response index (IBR) also evidenced worse environmental conditions in these sites. This result can indicate a negative influence of anthropogenic activities on the contamination of sediments and on the biological responses of fish. This study presented the first ecotoxicological data for the species and suggested that these chronic exposures can cause adverse effects on this fish population. The data contribute to the understanding of local environmental quality and can be applied in the future to the environmental and social management of marine protected areas.

Rab11 is required for neurite pruning and developmental membrane protein degradation in Drosophila sensory neurons.

Neurons, with their distinct neurites, require elaborate membrane trafficking pathways and regulation to uphold neurite identity and to be able to respond to neuronal or developmental stimuli. In a survey of trafficking regulators required for developmental dendrite pruning in Drosophila sensory neurons, we identified the small GTPase Rab11, a regulator of recycling endosomes. Dendrite pruning requires the developmentally regulated degradation of the cell adhesion molecule Neuroglian, and loss of Rab11 causes defects in the developmental degradation of Neuroglian and another target, the ion channel Ppk26. Rab11 often links vesicles to molecular motors, and we find that loss of the microtubule motor dynein also leads to defective Neuroglian and Ppk26 degradation. Loss of Rab11 also leads to defects in larval dendrite elaboration, and Neuroglian and Ppk26 localization is already altered at this stage. Our data highlight the importance of membrane protein recycling during development.

Integrated assessment of sediment contaminant levels and biological responses in sentinel fish species Atherinella brasiliensis from a sub-tropical estuary in south Atlantic.

This study combined data of the concentrations of metals, polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals and personal hygiene products (PPCPs) in the sediments and the biological responses of the Atherinella brasiliensis fish in two different sites and climate seasons in the Estuarine-Lagoon Complex of Iguape-Cananéia, Southeast Brazil. The presence of metals, PAHs, and PPCPs were observed in the sediments demonstrating the contamination throughout the system with contributions of sewage and residues disposal, oil and combustion of biomass and fossil fuels. Higher contaminations were identified in the point of greater human presence (C - Cananéia City), especially during the cold-dry season. The influence of anthropic activities and variations in the estuarine conditions, such as lower hydrodynamics during the lower rainfall period, were observed. In fish, spatial and seasonal changes in the parameters of oxidative stress and biotransformation, genotoxicity and histopathological alterations followed the same trend, with more pronounced responses in C in the cold-dry season. The biological responses of the fish revealed adverse effects in the local species population and indicated the presence of metals, PAHs and PPCPs as stressors. The multivariate analysis and the integrated biomarker response index (IBR) corroborated with these results, also indicating that site C had the worst environmental quality. The present study provides new information about the contamination of the sediments of Estuarine-Lagoon Complex of Iguape-Cananéia and the chronic exposure to contaminants in A. brasiliensis. Therefore, contributing to a better understanding of the local environmental quality with data that can support protective management of the area.

The influence of solid-liquid coefficient in the fate of pharmaceuticals and personal care products in aerobic wastewater treatment.

Wastewater treatment plants (WWTPs) are considered to be a source of environmental contamination by micropollutants, especially from pharmaceuticals and personal care products (PCPs). The pathway of those compounds during sewage treatment has been investigated, but data from real-scale WWTPs is still missing (for example, the values of the solid-liquid coefficient (Kd) during treatment). This paper uses the Kd values for some pharmaceuticals and PCPs (fenofibrate, gemfibrozil, propranolol, metoprolol, salicylic acid, acetylsalicylic acid, ibuprofen, diclofenac, naproxen, fenoprofen, caffeine, triclosan, methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben) to describe the micropollutants' behavior in the treatment process. In order to attain this data, an aerobic wastewater treatment plant located in Brazil was studied. Six samplings were carried out and a mass balance was performed, associating the concentrations of the micropollutants in the liquid phase with the solid phase (sludge and suspended solids). Of all the compounds analyzed, caffeine was the most biodegradable pollutant, as almost 98% of its mass was biodegraded. In contrast, triclosan had the highest load in sludge (median of 163.0 mg day-1) and adsorbed in SS (median of 0.593 mg day-1) at the output. Summing up, each micropollutant had a specific way to be removed during wastewater treatment.