Keratinocytes as Depository of Ammonium-Inducible Glutamine Synthetase: Age- and Anatomy-Dependent Distribution in Human and Rat Skin

In inner organs, glutamine contributes to proliferation, detoxification and establishment of a mechanical barrier, i.e., functions essential for skin, as well. However, the age-dependent and regional peculiarities of distribution of glutamine synthetase (GS), an enzyme responsible for generation of glutamine, and factors regulating its enzymatic activity in mammalian skin remain undisclosed. To explore this, GS localization was investigated using immunohistochemistry and double-labeling of young and adult human and rat skin sections as well as skin cells in culture. In human and rat skin GS was almost completely co-localized with astrocyte-specific proteins (e.g. GFAP). While GS staining was pronounced in all layers of the epidermis of young human skin, staining was reduced and more differentiated among different layers with age. In stratum basale and in stratum spinosum GS was co-localized with the adherens junction component ß-catenin. Inhibition of, glycogen synthase kinase 3β in cultured keratinocytes and HaCaT cells, however, did not support a direct role of ß-catenin in regulation of GS. Enzymatic and reverse transcriptase polymerase chain reaction studies revealed an unusual mode of regulation of this enzyme in keratinocytes, i.e., GS activity, but not expression, was enhanced about 8–10 fold when the cells were exposed to ammonium ions. Prominent posttranscriptional up-regulation of GS activity in keratinocytes by ammonium ions in conjunction with widespread distribution of GS immunoreactivity throughout the epidermis allows considering the skin as a large reservoir of latent GS. Such a depository of glutamine-generating enzyme seems essential for continuous renewal of epidermal permeability barrier and during pathological processes accompanied by hyperammonemia

A comparative analysis of trace metal pollution parity between sandy and shaly soils: evidence from two mechanic villages in the Imo River basin

Heavy metal enrichment parity in sandy and shaly mechanic village (MV) soils was studied in order to explain the technical and economic imperatives of setting an environmentally friendly MV on either soil. Okigwe (shaly) and Nekede (sandy) mechanic village soils in the Imo River basin Nigeria were tested and compared. Spectroscopic analysis of the soil samples collected from three surface layers (L), where L1: 0-10 cm; L2: 10-20 cm and L3: 90-100 cm shows that Pb \u3e Cu \u3e Mn in the Okigwe MV, and Mn \u3e Pb \u3e Cu in the Nekede MV. Mean concentration of metals (mg kg-1) in Okigwe MV are Fe: 51,291 ± 18,148, Ni: 22 ± 4, Cd: 20 ± 3, Pb: 500 ± 513, Cu: 616 ± 369, Cr: 16 ± 9, and Mn: 378 ± 207. Similarly, Nekede MV has 22,101 ± 7,273 of Fe; 8 ± 0.8 of Ni; 11 ± 4 of Cd; 320 ± 122 of Pb; 265 ± 145 of Cu; 11 ± 2 of Cr; and 350 ± 191 of Mn. Pollution factor (Pf): Okigwe MV has 0.77, and Nekede has 0.68. Pollution degree: Okigwe MV is greater in L1 and L2, while Nekede is greater in L3, with greater potentials for Pb, and Mn mobility than the Okigwe. Both have similar trends of metal distribution, and significant correlation with their background values. Low clay-silt content in Nekede MV soil suggests low sorption capacity, whereas the high claysilt content (47-64%) of the Okigwe soil suggests lower bioavailability. Infiltration basin is not recommended in a MV on sandy soil if water table is near surface. In such case, the MV must be moved to a location where water table is[37 m, or have clay-shale material transported to the site to form impervious layer base for detention basin. For groundwater safety and sustainability, shaly soils are most recommended for MVs so that detention basin could be economically used for storm water treatment

Inter-regional variability in environmental availability of fungicide derived copper in vineyard soils : an Australian case study

This study determined the environmental availability of copper (Cu) in Australian vineyard soils contaminated with fungicide derived Cu residues, and investigated the soil characteristics correlated with differences in Cu availability between regions. Concentrations of 0.01 M calcium chloride extractable Cu, measured in surface soils collected from 98 vineyards in 10 different grape-growing regions of Australia, ranged from &lt;0.1 to 0.94 mg/kg and accounted for 0.10&minus;1.03% of the total Cu concentrations in the soils. Differences in the calcium chloride extractable Cu concentrations were related to the total Cu concentration and soil properties, including pH, clay, exchangeable K, silt, and calcium carbonate. The information generated from this study may prove useful in devising strategies to reduce the availability and toxicity of Cu in agricultural soils.<br /