Environmental and health implications of Pb-bearing particles in settled urban dust from an arid city affected by Pb-Zn factory emissions.

Metal-rich particles originating from non-ferrous metallurgical activities are the primary source of atmospheric metals in urban environments. These particles vary in size, morphology, and elemental compositions and they undergo weathering processes that alter their composition and affect their toxicity. This study focuses on lead (Pb)-rich particles in settled urban dust within an arid and dusty city, Torreón in North Mexico, affected by Met-Mex Peñoles complex, one of the world's largest Ag-Cd-Pb-Zn smelting and refining facilities in operating since 1901.

Molecular determinants for cold adaptation in an Antarctic Na/K-ATPase.

Enzymes from ectotherms living in chronically cold environments have evolved structural innovations to overcome the effects of temperature on catalysis. Cold adaptation of soluble enzymes is driven by changes within their primary structure or the aqueous milieu. For membrane-embedded enzymes, like the Na/K-ATPase, the situation is different because changes to the lipid bilayer in which they operate may also be relevant.

Physiological adaptation of an Antarctic Na+/K+-ATPase to the cold.

Because enzymatic activity is strongly suppressed by the cold, polar poikilotherms face significant adaptive challenges. For example, at 0°C the catalytic activity of a typical enzyme from a temperate organism is reduced by more than 90%. Enzymes embedded in the plasma membrane, such as the Na(+)/K(+)-ATPase, may be even more susceptible to the cold because of thermal effects on the lipid bilayer.