Nitrate concentration in drinking water supplies in selected communities of Ibadan Southeast local government, Ibadan, Nigeria

Elevated levels of nitrate in drinking water have been associated with adverse health effects. Most susceptible to nitrate toxicity are infants under six months of age and pregnant women. This study assesses the nitrate concentration of 48 randomly selected wells in an urban-slum setting in Ibadan South East Local Government Area (IBSELGA), Nigeria. The coordinates of the wells were mapped with a hand-held Global Positioning System (GPS). The nitrate concentration ranged between 0.00 and 42.80 mgL-1 with a mean of log10 of 0.735 and a geometric mean of 5.43 mgL-1; and 0.00 and 93.30 mgL-1 with a mean of log10 of 0.696 and a geometric mean of 4.97 mg L-1 for the wet and dry seasons, respectively. During the wet season, the levels of nitrate in all the wells were within the WHO permissible limit of 45 mg L-1 NO3. However, during the dry season, few of the wells; six (12.5%) dried up completely. Out of the remaining 42 wells, six (14.3%) had nitrate concentration which exceeded the permissible limit. This same set of wells lacked sanitary features such as lining and cover. Out of the 48 wells, 30 (62.5%) and 24 (50%) were located at ≤10 m from the septic tank/pit latrine and refuse  dumps, respectively. Nitrate maps were developed using Georeferenced data for the water points. The nitrate exceedence map produced showed water sources within the study area with nitrate concentration exceeding the recommended limit and therefore requiring urgent intervention. The results of this study will serve as indicator for determining risk areas with respect to nitrate concentration in drinking water and therefore help in decision making activities.Key words: Global positioning system, Ibadan, nitrate, nitrate exceedence, wells, urban slum

Protein Interactions of the Vesicular Glutamate Transporter VGLUT1

Exocytotic release of glutamate depends upon loading of the neurotransmitter into synaptic vesicles by vesicular glutamate transporters, VGLUTs. The major isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in synapses of the adult rodent brain that correlates with the probability of release and potential for plasticity. Indeed, expression of different VGLUT protein isoforms confers different properties of release probability. Expression of VGLUT1 or 2 protein also determines the kinetics of synaptic vesicle recycling. To identify molecular determinants that may be related to reported differences in VGLUT trafficking and glutamate release properties, we investigated some of the intrinsic differences between the two isoforms. VGLUT1 and 2 exhibit a high degree of sequence homology, but differ in their N- and C-termini. While the C-termini of VGLUT1 and 2 share a dileucine-like trafficking motif and a proline-, glutamate-, serine-, and threonine-rich PEST domain, only VGLUT1 contains two polyproline domains and a phosphorylation consensus sequence in a region of acidic amino acids. The interaction of a VGLUT1 polyproline domain with the endocytic protein endophilin recruits VGLUT1 to a fast recycling pathway. To identify trans-acting cellular proteins that interact with the distinct motifs found in the C-terminus of VGLUT1, we performed a series of in vitro biochemical screening assays using the region encompassing the polyproline motifs, phosphorylation consensus sites, and PEST domain. We identify interactors that belong to several classes of proteins that modulate cellular function, including actin cytoskeletal adaptors, ubiquitin ligases, and tyrosine kinases. The nature of these interactions suggests novel avenues to investigate the modulation of synaptic vesicle protein recycling