Ca2+ Regulates the Drosophila Stoned-A and Stoned-B Proteins Interaction with the C2B Domain of Synaptotagmin-1

The dicistronic Drosophila stoned gene is involved in exocytosis and/or endocytosis of synaptic vesicles. Mutations in either stonedA or stonedB cause a severe disruption of neurotransmission in fruit flies. Previous studies have shown that the coiled-coil domain of the Stoned-A and the µ-homology domain of the Stoned-B protein can interact with the C2B domain of Synaptotagmin-1. However, very little is known about the mechanism of interaction between the Stoned proteins and the C2B domain of Synaptotagmin-1. Here we report that these interactions are increased in the presence of Ca2+. The Ca2+-dependent interaction between the µ-homology domain of Stoned-B and C2B domain of Synaptotagmin-1 is affected by phospholipids. The C-terminal region of the C2B domain, including the tryptophan-containing motif, and the Ca2+ binding loop region that modulate the Ca2+-dependent oligomerization, regulates the binding of the Stoned-A and Stoned-B proteins to the C2B domain. Stoned-B, but not Stoned-A, interacts with the Ca2+-binding loop region of C2B domain. The results indicate that Ca2+-induced self-association of the C2B domain regulates the binding of both Stoned-A and Stoned-B proteins to Synaptotagmin-1. The Stoned proteins may regulate sustainable neurotransmission in vivo by binding to Ca2+-bound Synaptotagmin-1 associated synaptic vesicles

Protein Glycosylation in Helicobacter pylori: Beyond the Flagellins?

Glycosylation of flagellins by pseudaminic acid is required for virulence in Helicobacter pylori. We demonstrate that, in H. pylori, glycosylation extends to proteins other than flagellins and to sugars other than pseudaminic acid. Several candidate glycoproteins distinct from the flagellins were detected via ProQ-emerald staining and DIG- or biotin- hydrazide labeling of the soluble and outer membrane fractions of wild-type H. pylori, suggesting that protein glycosylation is not limited to the flagellins. DIG-hydrazide labeling of proteins from pseudaminic acid biosynthesis pathway mutants showed that the glycosylation of some glycoproteins is not dependent on the pseudaminic acid glycosylation pathway, indicating the existence of a novel glycosylation pathway. Fractions enriched in glycoprotein candidates by ion exchange chromatography were used to extract the sugars by acid hydrolysis. High performance anion exchange chromatography with pulsed amperometric detection revealed characteristic monosaccharide peaks in these extracts. The monosaccharides were then identified by LC-ESI-MS/MS. The spectra are consistent with sugars such as 5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-manno-nonulosonic acid (Pse5Ac7Ac) previously described on flagellins, 5-acetamidino-7-acetamido-3,5,7,9-tetradeoxy-L-glycero-L-manno-nonulosonic acid (Pse5Am7Ac), bacillosamine derivatives and a potential legionaminic acid derivative (Leg5AmNMe7Ac) which were not previously identified in H. pylori. These data open the way to the study of the mechanism and role of protein glycosylation on protein function and virulence in H. pylori

Major Cellular and Physiological Impacts of Ocean Acidification on a Reef Building Coral

As atmospheric levels of CO2 increase, reef-building corals are under greater stress from both increased sea surface temperatures and declining sea water pH. To date, most studies have focused on either coral bleaching due to warming oceans or declining calcification due to decreasing oceanic carbonate ion concentrations. Here, through the use of physiology measurements and cDNA microarrays, we show that changes in pH and ocean chemistry consistent with two scenarios put forward by the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, before affects on biomineralisation are apparent at the phenotype level. Under high CO2 conditions corals at the phenotype level lost over half their Symbiodinium populations, and had a decrease in both photosynthesis and respiration. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrate upregulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur before impacts on calcification

A prospective, multi-method, multi-disciplinary, multi-level, collaborative, social-organisational design for researching health sector accreditation [LP0560737]

BACKGROUND: Accreditation has become ubiquitous across the international health care landscape. Award of full accreditation status in health care is viewed, as it is in other sectors, as a valid indicator of high quality organisational performance. However, few studies have empirically demonstrated this assertion. The value of accreditation, therefore, remains uncertain, and this persists as a central legitimacy problem for accreditation providers, policymakers and researchers. The question arises as to how best to research the validity, impact and value of accreditation processes in health care. Most health care organisations participate in some sort of accreditation process and thus it is not possible to study its merits using a randomised controlled strategy. Further, tools and processes for accreditation and organisational performance are multifaceted. METHODS/DESIGN: To understand the relationship between them a multi-method research approach is required which incorporates both quantitative and qualitative data. The generic nature of accreditation standard development and inspection within different sectors enhances the extent to which the findings of in-depth study of accreditation process in one industry can be generalised to other industries. This paper presents a research design which comprises a prospective, multi-method, multi-level, multi-disciplinary approach to assess the validity, impact and value of accreditation. DISCUSSION: The accreditation program which assesses over 1,000 health services in Australia is used as an exemplar for testing this design. The paper proposes this design as a framework suitable for application to future international research into accreditation. Our aim is to stimulate debate on the role of accreditation and how to research it.Jeffrey Braithwaite, Johanna Westbrook, Marjorie Pawsey, David Greenfield, Justine Naylor, Rick Iedema, Bill Runciman, Sally Redman, Christine Jorm, Maureen Robinson, Sally Nathan and Robert Gibber

Impact of sediment type, light and nutrient availability on benthic diatom communities of a large estuarine bay: Moreton Bay, Australia

Shifts in diatom species composition may be used to infer past changes in environmental conditions in fresh, estuarine and marine systems. Establishing the primary drivers of present day diatom community composition is a vital step in their use as a proxy for past conditions. Moreton Bay, Australia, has experienced extensive modification of its catchments and western and southern shorelines. Regional weather patterns and terrestrial runoff have created a gradient in water quality from relatively degraded western and southern areas to relatively pristine northern and eastern areas. The aim of this study was to examine the relative impact of short term changes to light and/or nutrient availability and long term changes in sediment type, light and nutrient availability to subtidal benthic community composition. Short term changes were imposed using a manipulative field experiment whilst long term changes were obtained from a field survey of sites across the gradient of water quality. Diatoms were found to be the dominant microalgal group at all studied sites. The diatom communities were comprised primarily of small benthic epipsammic species and community composition was primarily driven by changes in sediment silt content. Short term changes in light and/or nutrient availability had little impact on community composition. In this open estuarine system the use of diatom indices to infer past water quality must take into account the sediment silt content in their interpretations