The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis.
The crystal structure of human p38 mitogen-activated protein (MAP) kinase in complex with a potent and highly specific pyridinyl-imidazole inhibitor has been determined at 2.0 A resolution. The structure of the kinase, which is in its unphosphorylated state, is similar to that of the closely-related ERK2. The inhibitor molecule is bound in the ATP pocket. A hydrogen bond is made between the pyridyl nitrogen of the inhibitor and the main chain amido nitrogen of residue 109, analogous to the interaction from the N1 atom of ATP. The crystal structure provides possible explanations for the specificity of this class of inhibitors. Other protein kinase inhibitors may achieve their specificity through a similar mechanism. The structure also reveals a possible second binding site for this inhibitor, with currently unknown function.
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