The White-Spotted Bamboo Shark Genome Reveals Chromosome Rearrangements and Fast-Evolving Immune Genes of Cartilaginous Fish.

Chondrichthyan (cartilaginous fish) occupies a key phylogenetic position and is important for investigating evolutionary processes of vertebrates. However, limited whole genomes impede our in-depth knowledge of important issues such as chromosome evolution and immunity. Here, we report the chromosome-level genome of white-spotted bamboo shark. Combing it with other shark genomes, we reconstructed 16 ancestral chromosomes of bamboo shark and illustrate a dynamic chromosome rearrangement process. We found that genes on 13 fast-evolving chromosomes can be enriched in immune-related pathways. And two chromosomes contain important genes that can be used to develop single-chain antibodies, which were shown to have high affinity to human disease markers by using enzyme-linked immunosorbent assay. We also found three bone formation-related genes were lost due to chromosome rearrangements. Our study highlights the importance of chromosome rearrangements, providing resources for understanding of cartilaginous fish diversification and potential application of single-chain antibodies.

Microbial reductive transformation of iron-rich tailings in a column reactor and its environmental implications to arsenic reactive transport in mining tailings.

The evolution of iron minerals under buried conditions is one of the most important processes controlling the mineral composition and heavy metal transportation in sediments. Microbial-mediated reduction plays a critical role in iron mineral transformation in natural environment. This study examined the transformation pathways of iron minerals mediated by bacteria and the changes of associated arsenic species in iron-rich mine tailings. Static and column reactions were designed to monitor variations of minerals and released iron and arsenic, a reactive transport model was simulated to support laboratory results. Laboratory experiments showed that major ferric minerals were preferentially dissolved and reduced by dissimilatory iron-reducing bacteria. The released Fe3+ in fluid promoted oxidative dissolution of pyrite and arsenopyrite, and precipitation of oxides and carbonates. The arsenic released to fluid was inferred to be immobilized by both pristine ferrihydrite and newly formed hydrous ferric oxides via surface complexation. The reaction system maintained a steady-state of iron mineral transformation and arsenic (im)mobilization. In the latter stage of column reactor experiments, continuous reaction and removal of dissolved Fe3+ and Fe2+ destabilized the state, leading to arsenic re-location and eventually rising concentration in fluid. The findings implicate that microbial-mediated iron mineral evolution remarkably influence the natural mineral assemblages and the fate of contaminant transport in the environment, and that deposition of iron oxides is essential in environmental protection and pollution recovery.

Radium in hydraulic fracturing wastewater: distribution in suspended solids and implications to its treatment by sulfate co-precipitation.

High concentrations of barium (Ba), strontium (Sr) and radium (Ra) are present in both the liquid and suspended solid portions of wastewater produced from hydraulic fracturing. These high concentrations often require special treatment in which the solid and liquid portions are separated and then independently treated prior to disposal. The solids are typically disposed in landfills while the liquids are further treated, recycled for future hydraulic fracturing, or disposed via injection wells. Finding optimal treatment methods of both the solid and the liquid fractions requires a thorough understanding of potential Ra mobility from both the raw suspended solids and mineral precipitates formed during treatment. Using a sequential extraction procedure, we found that, without treatment, more than 50% of Ra-226 in the suspended solids was associated with soluble salts and readily exchangeable fractions. When the liquid portion of the wastewater was treated by mixing with acid mine drainage (AMD), which contained high sulfate concentrations, approximately 80-97% of the total Ra-226 in the mixture solution is found in the insoluble sulfate fraction of the precipitate. The activity of Ra-226 sequestered in the precipitated solid sulfate fractions is positively correlated with the Sr/Ba ratio of the wastewater-AMD solution. We discuss implications of these findings for effective long-term management of elevated radium in both solid and liquid wastes.

Glutathione regulates the transfer of iron-sulfur cluster from monothiol and dithiol glutaredoxins to apo ferredoxin.

Holo glutaredoxin (Grx) is a homo-dimer that bridges a [2Fe-2S] cluster with two glutathione (GSH) ligands. In this study, both monothiol and dithiol holo Grxs are found capable of transferring their iron-sulfur (FeS) cluster to an apo ferredoxin (Fdx) through direct interaction, regardless of FeS cluster stability in holo Grxs. The ligand GSH molecules in holo Grxs are unstable and can be exchanged with free GSH, which inhibits the FeS cluster transfer from holo Grxs to apo Fdx. This phenomenon suggests a novel role of GSH in FeS cluster trafficking.