Model-based analysis of microbial consortia and microbial products in an anammox biofilm reactor.

A mathematical model for a granular biofilm reactor for leachate treatment was validated by long-term measured data to investigate the mechanisms and drivers influencing biological nitrogen removal and microbial consortia dynamics. The proposed model, based on Activated Sludge Model (ASM1), included anaerobic ammonium oxidation (anammox), nitrifying and heterotrophic denitrifying bacteria which can attach and grow on granular activated carbon (GAC) particles. Two kinetic descriptions for the model were proposed: with and without soluble microbial products (SMP) and extracellular polymeric substance (EPS). The model accuracy was checked using recorded total inorganic nitrogen concentrations in the effluent and estimated relative abundance of active bacteria using quantitative fluorescence in-situ hybridization (qFISH). Results suggested that the model with EPS kinetics fits better for the relative abundance of anammox bacteria and nitrifying bacteria compared to the model without EPS. The model with EPS and SMP confirms that the growth and existence of heterotrophs in anammox biofilm systems slightly increased due to including the kinetics of SMP production in the model. During the one-year simulation period, the fractions of autotrophs and EPS in the biomass were almost stable but the fraction of heterotrophs decreased which is correlated with the reduction in nitrogen surface loading on the biofilm.

Implications of tropical cyclones on damage and potential recovery and restoration of logged forests in Vietnam.

Many natural forests in Southeast Asia are degraded following decades of logging. Restoration of these forests is delayed by ongoing logging and tropical cyclones, but the implications for recovery are largely uncertain. We analysed meteorological, satellite and forest inventory plot data to assess the effect of Typhoon Doksuri, a major tropical cyclone, on the forest landscapes of central Vietnam consisting of natural forests and plantations. We estimated the return period for a cyclone of this intensity to be 40 years. Plantations were almost twice as likely to suffer cyclone damage compared to natural forests. Logged natural forests (9-12 years after cessation of government-licensed logging) were surveyed before and after the storm with 2 years between measurements and remained a small biomass carbon sink (0.1 ± 0.3 Mg C ha-1 yr-1) over this period. The cyclone reduced the carbon sink of recovering natural forests by an average of 0.85 Mg C ha-1 yr-1, less than the carbon loss due to ongoing unlicensed logging. Restoration of forest landscapes in Southeast Asia requires a reduction in unlicensed logging and prevention of further conversion of degraded natural forests to plantations, particularly in landscapes prone to tropical cyclones where natural forests provide a resilient carbon sink. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.

Survival rates and complication types for single implants provided at the Melbourne Dental School.

BACKGROUND: Single implants and implant-supported single crowns (ISSCs) have become popular treatment modalities for single tooth replacement. Studies have identified high implant survival rates, but also many complications. The aim of this five-year retrospective study was to assess the survival rates, complication types and occurrences for single implants and ISSCs at the Melbourne Dental School (MDS) in Victoria, Australia. METHODS: A search of the Royal Dental Hospital of Melbourne (RDHM) database was conducted for data on all implant treatment and reported complications during the period between 1 January 2005 and 31 December 2009. Complications were categorized into surgical, biological and restorative types. RESULTS: A total of 622 implant fixtures and 444 ISSCs were inserted into 406 patients. Seventeen implants failed during the mean follow-up time of 2.18 years, yielding a 2.7% failure rate and an estimated one- and five-year survival rate of 98.8% and 93.9%, respectively. The cumulative surgical, biological and restorative complication incidences were 11.9%, 17.6% and 14.1%, respectively. CONCLUSIONS: This study confirmed that single tooth replacement using implant therapy within a teaching environment had a high survival rate. However, complications frequently occurred. This article only provides a descriptive analysis. Correlation analysis between variables would provide greater insight into the causes of complications.

N-Linked oligosaccharides of the H-2Dk histocompatibility protein heavy chain influence its transport and cellular distribution.

The H-2K and H-2D proteins encoded by the K and D region of the major histocompatibility complex of the mouse were isolated by immunoprecipitation with specific antisera and resolved by two-dimensional gel electrophoresis. Of these two polypeptides, the H-2Dk glycoproteins isolated from macrophages of C3H/HeHa mice exhibit distinct cell surface and cytoplasmic forms although they share a strong degree of homology in the polypeptide backbone. Structurally they differ in their oligosaccharide structures. The structure of the oligosaccharides on the intracellular forms is of the high mannose type while the same structures on the cell surface forms are of the complex type. In the absence of all three oligosaccharide side chains, the unglycosylated polypeptides are expressed on the cell surface. In contrast, polypeptides containing one, two, or all three oligosaccharide side chains of the high mannose type are not transported to the cell surface. Cell surface expression of these glycoproteins requires processing of the oligosaccharide side chains from the high mannose form to the complex type. However, not all oligosaccharide antennae have to be terminally modified since H-2Dk glycoproteins synthesized in the presence of oligosaccharide-processing enzyme inhibitors such as swainsonine or monensin are also transported to the cell surface. H-2Dk glycoproteins containing oligosaccharide structures of the complex type but lacking terminal sialic acids are found on the cell surface, suggesting that sialylation is not required for transport. These results indicate that the oligosaccharide structures of the H-2Dk glycoproteins act to influence their cellular distribution.

Identification and characterization of a murine receptor for galactose-terminated glycoproteins.

The asialoglycoprotein receptor, the hepatic binding lectin for galactose-terminated glycoproteins, has been isolated and characterized from human, rabbit and rat liver. Several recent studies have shown the existence of the same receptor in murine liver. However, the biochemical structure of the receptor in murine liver has not been resolved. In this paper, we describe the identification and purification of the receptor for asialoglycoproteins from murine liver. The purified receptor has three polypeptides with apparent molecular weights of 42,000, 45,000 and 51,000, respectively, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Furthermore, our studies suggest that the receptor from murine liver is very similar to its counterpart in rat liver, although some potential interesting differences have also been observed. Initial studies indicate that this receptor is well conserved in different mouse strains.

Quality control for qualitative assays: quantitative QC procedure designed to assure analytical quality required for an ELISA of hepatitis B surface antigen.

An assay for hepatitis B surface antigen (HBsAg) should reliably detect 0.2 microgram/L, the lowest reported concentration in an asymptomatic blood donor. The difference between this concentration and the assay cutoff defines the analytical quality requirement in a total error format. The design of a statistical QC procedure is critically dependent on the precision of the assay. The precision of a developmental ELISA of HBsAg under study ranged from 17.5% to 9.6% for controls containing 0.07 to 1.50 micrograms/L, respectively. Use of one positive control with the 1(3s), QC rule provided an 85% chance of detecting a critical loss of assay sensitivity; use of two positive controls increased the chance of detecting critical loss of assay sensitivity to nearly 100%. These rules are based on the precision of this developmental assay, and must be developed individually for other assays. The development of the proposed QC procedures illustrates how quantitative QC can be provided for qualitative assays.