Iron persistence in a distal hydrothermal plume supported by dissolved–particulate exchange

Hydrothermally sourced dissolved metals have been recorded in all ocean basins. In the oceans\u27 largest known hydrothermal plume, extending westwards across the Pacific from the Southern East Pacific Rise, dissolved iron and manganese were shown by the GEOTRACES program to be transported halfway across the Pacific. Here, we report that particulate iron and manganese in the same plume also exceed background concentrations, even 4,000 km from the vent source. Both dissolved and particulate iron deepen by more than 350 m relative to(3)He-a non-reactive tracer of hydrothermal input-crossing isopycnals.Manganese shows no similar descent. Individual plume particle analyses indicate that particulate iron occurs within low-density organic matrices, consistent with its slow sinking rate of 5-10 m yr(-1). Chemical speciation and isotopic composition analyses reveal that particulate iron consists of Fe( III) oxyhydroxides, whereas dissolved iron consists of nanoparticulate Fe( III) oxyhydroxides and an organically complexed iron phase. The descent of plume-dissolved iron is best explained by reversible exchange onto slowly sinking particles, probably mediated by organic compounds binding iron. We suggest that in ocean regimes with high particulate iron loadings, dissolved iron fluxes may depend on the balance between stabilization in the dissolved phase and the reversibility of exchange onto sinking particles

The transmembrane protein meckelin (MKS3) is mutated in Meckel-Gruber syndrome and the wpk rat.

Meckel-Gruber syndrome is a severe autosomal, recessively inherited disorder characterized by bilateral renal cystic dysplasia, developmental defects of the central nervous system ( most commonly occipital encephalocele), hepatic ductal dysplasia and cysts and polydactyly(1-3). MKS is genetically heterogeneous, with three loci mapped: MKS1, 17q21-24 (ref. 4); MKS2, 11q13 ( ref. 5) and MKS3 ( ref. 6). We have refined MKS3 mapping to a 12.67-Mb interval (8q21.13-q22.1) that is syntenic to the Wpk locus in rat, which is a model with polycystic kidney disease, agenesis of the corpus callosum and hydrocephalus(7,8). Positional cloning of the Wpk gene suggested a MKS3 candidate gene, TMEM67, for which we identified pathogenic mutations for five MKS3-linked consanguineous families. MKS3 is a previously uncharacterized, evolutionarily conserved gene that is expressed at moderate levels in fetal brain, liver and kidney but has widespread, low levels of expression. It encodes a 995 - amino acid seven-transmembrane receptor protein of unknown function that we have called meckelin