Rehabilitation of tropical urban streams improves their structure and functioning.

Urban streams are affected by a complex combination of stressors, which modify physical habitat structure, flow regime, water quality, biological community composition, and ecosystem processes and services, thereby altering ecosystem structure and functioning. Rehabilitation projects have been undertaken in several countries to rehabilitate urban streams. However, stream rehabilitation is still rarely reported for neotropical regions. In addition, most studies focus on structural aspects, such as water quality, sediment control, and flood events, without considering ecosystem function indicators. Here, we evaluated the structure and functioning of three 15-y old rehabilitated urban stream sites in comparison with three stream sites in the best available ecological condition (reference), three sites with moderate habitat alteration, and three severely degraded sites. Compared to degraded streams, rehabilitated streams had higher habitat diversity, sensitive macroinvertebrate taxa richness, and biotic index scores, and lower biochemical oxygen demand, primary production, sediment deposition, and siltation. However, rehabilitated streams had higher primary production than moderate and reference streams, and lower canopy cover, habitat diversity, sensitive macroinvertebrate taxa richness, and biotic index scores than reference streams. These results indicate that rehabilitated streams have better structural and functional condition than degraded streams, but do not strongly differ from moderately altered streams, nor have they reached reference stream condition. Nonetheless, we conclude that rehabilitation is effective in removing streams from a degraded state by improving ecosystem structure and functioning. Furthermore, the combined use of functional and structural indicators facilitated an integrative assessment of stream ecological condition and distinguished stream conditions beyond those based on water quality indicators.

Virus-Like Particle-Encapsulated Doxorubicin Enters and Kills Murine Tumor Cells Differently from Free Doxorubicin.

The use of nanoparticles as chemotherapeutic carriers has been suggested as a way to overcome a range of side effects associated with classical cancer treatment such as poor selectivity and tumor resurgence. Obtaining precise control of the size and shape of therapeutic nanoparticles is crucial to optimize the targeting of tumor sites. In this work, it is shown that a previously developed system of polypeptide encapsulating individual DNA molecules, that forms rod-shaped nanoparticles of precisely controlled aspect ratio, can be loaded with the DNA-intercalating chemotherapeutic drug doxorubicin (DOX). It is characterized the size and shape of the DOX loaded-Virus-Like DNA Particles (DOX-VLDP) and shown that in this system the DOX payload does not leak out. Through in vitro cell studies, it is shown that DOX-VLDP is internalized by melanoma tumor cells (B16F10 cells) in a delayed and endocytosis-dependent way culminating in increased cytotoxicity and selectivity to tumor cells in comparison with free DOX. In addition, it is found that DOX-VLDP trigger apoptosis and autophagy pathways in treated cells. Taken together, the data on the DOX-VLDP nanoparticles shows that they kill cancer cells differently from free DOX.