Source Water Characteristics and Building-specific Factors Influence Corrosion and Point of Use Water Quality in a Decentralized Arctic Drinking Water System.

Access to clean and safe drinking water is a perpetual concern in Arctic communities because of challenging climatic conditions, limited options for the transportation of equipment and process chemicals, and the ongoing effects of colonialism. Water samples were gathered from multiple locations in a decentralized trucked drinking water system in Nunavut, Canada, over the course of one year. The results indicate that point of use drinking water quality was impacted by conditions in the source water and in individual buildings and strongly suggest that lead and copper measured at the tap were related to corrosion of onsite premise plumbing components. Humic-like substances were the dominant organic fraction in all samples, as determined by regional integration of fluorescence data. Iron and manganese levels in the source water and throughout the water system were higher in the winter and lower in the summer months. Elevated concentrations of copper (>2000 µg L-1) and lead (>5 µg L-1) were detected in tap water from some buildings. Field flow fractionation coupled with inductively coupled plasma mass spectrometry and ultraviolet-visible spectrometry was used to demonstrate the link between source water characteristics (high organics, iron and manganese) and lead and copper in point of use drinking water.

The role of C. elegans Ena/VASP homolog UNC-34 in neuronal polarity and motility.

Ena/VASP proteins mediate the effects of guidance cues on the actin cytoskeleton. The single C. elegans homolog of the Ena/VASP family of proteins, UNC-34, is required for the migrations of cells and growth cones. Here we show that unc-34 mutant alleles also interact genetically with Wnt mutants to reveal a role for unc-34 in the establishment of neuronal polarity along the C. elegans anterior-posterior axis. Our mutant analysis shows that eliminating UNC-34 function results in neuronal migration and polarity phenotypes that are enhanced at higher temperatures, revealing a heat-sensitive process that is normally masked by the presence of UNC-34. Finally, we show that the UNC-34 protein is expressed broadly and accumulates in axons and at the apical junctions of epithelial cells. While most mutants lacked detectable UNC-34, three unc-34 mutants that contained missense mutations in the EVH1 domain produced full-length UNC-34 that failed to localize to apical junctions and axons, supporting the role for the EVH1 domain in localizing Ena/VASP family members.

UNC-6/netrin and SLT-1/slit guidance cues orient axon outgrowth mediated by MIG-10/RIAM/lamellipodin.

BACKGROUND: Axon migrations are guided by extracellular cues that can act as repellants or attractants. However, the logic underlying the manner through which attractive and repulsive responses are determined is unclear. Many extracellular guidance cues, and the cellular components that mediate their signals, have been implicated in both types of responses. RESULTS: Genetic analyses indicate that MIG-10/RIAM/lamellipodin, a cytoplasmic adaptor protein, functions downstream of the attractive guidance cue UNC-6/netrin and the repulsive guidance cue SLT-1/slit to direct the ventral migration of the AVM and PVM axons in C. elegans. Furthermore, overexpression of MIG-10 in the absence of UNC-6 and SLT-1 induces a multipolar phenotype with undirected outgrowths. Addition of either UNC-6 or SLT-1 causes the neurons to become monopolar. Moreover, the ability of UNC-6 or SLT-1 to direct the axon ventrally is enhanced by the MIG-10 overexpression. We also demonstrate that an interaction between MIG-10 and UNC-34, a protein that promotes actin-filament extension, is important in the response to guidance cues and that MIG-10 colocalizes with actin in cultured cells, where it can induce the formation of lamellipodia. CONCLUSIONS: We conclude that MIG-10 mediates the guidance of AVM and PVM axons in response to the extracellular UNC-6 and SLT-1 guidance cues. The attractive and repulsive guidance cues orient MIG-10-dependant axon outgrowth to cause a directional response.