Monosulfidic black ooze accumulations in sediments of the Geographe Bay area, Western Australia.

Mobilisation of sedimentary monosulfidic black ooze (MBO) may result in rapid deoxygenation and acidification of surface waters, and release of potentially toxic metals. This study examines the extent and nature of MBO accumulation in the Geographe Bay area, Western Australia. MBO accumulations were found to be widespread in benthic sediments of the Geographe Bay area with acid-volatile sulfide (AVS) contents as high as 320 µmol g(-1). The MBO materials often had unusually high dissolved sulfide (S(-II)) concentrations in their pore-waters (up to 610 mg L(-1)) and elevated elemental sulfur (S(0)) contents (up to 51 µmol g(-1)). Dissolved S(-II) is able to accumulate due to limited iron availability and S(0) is largely its partial oxidation product. The availability of organic carbon and Fe limited MBO accumulation at many sites. A comparison of AVS and simultaneously extracted metal (SEM) concentrations has shown that metals are likely to be bound in sulfide complexes.

Analysis of TYA protein regions necessary for formation of the Ty1 virus-like particle structure.

The yeast retrotransposon, Ty1, produces a macromolecular structure known as a virus-like particle (VLP) as an essential part of its replication cycle. The Ty1 Gag-like structural protein TYA, p1-440, alone is capable of directing assembly of the VLP. In order to determine the TYA sequences required for assembly, we have produced a series of truncated and deleted TYA forms and assessed their ability to assemble into particles. Removal of 100 amino acids from the C-terminus renders the TYA protein, p1-340, incapable of particle assembly; however, p1-363 with 77 residues missing from the C-terminus is capable of assembly. Removal of 40 amino acids from the N-terminus (p41-440 and p41-381) does not affect particle formation but more severely N-truncated forms, p71-381 and p100-381, are present as large aggregates within the cells and are therefore either incapable of or unavailable for VLP formation. Analysis of an internally deleted TYA, p1-381 delta 62-114, has identified this as a possible region of the TYA protein important for subunit:subunit interactions during the particle assembly.

An immunological analysis of Ty1 virus-like particle structure.

We present an immunological characterization of the Ty1 virus-like particle (VLP). A panel of monoclonal and polyclonal antibodies were raised against the TYA particle-forming protein. Using these antibodies in epitope availability assays two N-terminal regions of the TYA protein were mapped projecting from or at the surface of the proteinaceous shell of the VLP. Two different C-termini of the TYA protein, corresponding to the C-terminus of the full-length and truncated forms, were seen to be buried within the particle core and not available for antibody binding. RNase accessibility studies demonstrated a difference in the porosity of the protein shell surrounding the Ty1 nucleic acid between different particle types, suggesting differences in subunit organization.