Lipid profiling of the model temperate grass, Brachypodium distachyon

Lipids are essential metabolites in cells and they fulfil a variety of functions, including structural components of cellular membranes, energy storage, cell signalling, and membrane trafficking. In plants, changes in lipid composition have been observed in diverse responses ranging from abiotic and biotic stress to organogenesis. Knowledge of the lipid composition is an important first step towards understanding the function of lipids in any given biological system. As Brachypodium distachyon is emerging as the model species for temperate grass research, it is therefore fundamentally important to gain insights of its lipid composition. We used HPLC-coupled with tandem mass spectrometry to profile and quantify levels of sphingolipids and glycerophospholipids in shoots and undifferentiated cells in suspension cultures of B. distachyon. A total of 123 lipids belonging to 10 classes were identified and quantified. Our results showed that there are differences in lipid profiles and levels of individual lipid species between shoots and undifferentiated cells in suspension cultures. Additionally, we showed that 4-sphingenine (d18:1^??4) is the main unsaturated dihydroxy-long chain base (LCB) in B. distachyon, and we were unable to detect d18:1^??8, which is the main unsaturated dihydroxy-LCB in the model dicotyledonous species, Arabidopsis thaliana. This work serves as the first step towards a comprehensive characterization of the B. distachyon lipidome that will complement future biochemical studies.     

Analyses of genetic population structure of two ecologically important mangrove tree species, Bruguiera gymnorrhiza and Kandelia obovata from different river basins of Iriomote Island of the Ryukyu Archipelago, Japan

We analyzed nuclear and chloroplast microsatellite makers to assess genetic diversity and examine genetic structure of two mangrove tree species, Bruguiera gymnorrhiza and Kandelia obovata recovered from nine major river basins of Iriomote Island of the Ryukyu Archipelago, Japan. The average number of alleles per nuclear locus per population was 2.6 in B. gymnorrhiza and 1.7 in K. obovata. Bayesian clustering analysis using InStruct identified two genetic clusters in B. gymnorrhiza and three clusters in K. obovata. Chloroplast microsatellites revealed two dominant haplotypes from B. gymnorrhiza and three haplotypes from K. obovata. The overall result suggests low genetic diversity for both species. AMOVA for nuclear microsatellites showed 9.3?% of population variation in B. gymnorrhiza. Although genetic differentiation between several populations was significant in this species, F _ST suggested low to moderate level of differentiations between most of the populations. Distribution of genetic clusters and chloroplast haplotypes also suggested weak differentiations among B. gymnorrhiza populations. In K. obovata, population variation was, however, relatively high (27.8?%). The high differentiation between K. obovata populations was also suggested from the F _ST and genetic clusters from nuclear microsatellites, and chloroplast haplotypes. A significant correlation between chloroplast genetic distances and coastline distances as well as haplotype distributions for both species suggest that propagules from each species mostly disperse to the neighboring river basins. While significant F _IS and higher percentage of admixed clusters from nuclear microsatellites suggested inbreeding, continual gene exchange by propagule dispersal among populations especially among neighboring populations was suggested for both species from maternally inherited chloroplast microsatellites analyses.     

Anesthesiologists' and surgeons' perceptions about routine pre-operative testing in low-risk patients: application of the Theoretical Domains Framework (TDF) to identify factors that influence physicians' decisions to order pre-operative tests

ABSTRACT: BACKGROUND: Routine pre-operative tests for anesthesia management are often ordered by bothanesthesiologists and surgeons for healthy patients undergoing low-risk surgery. TheTheoretical Domains Framework (TDF) was developed to investigate determinants ofbehaviour and identify potential behaviour change interventions. In this study, the TDF is used to explore anaesthesiologists' and surgeons' perceptions of ordering routine tests forhealthy patients undergoing low-risk surgery. METHODS: Sixteen clinicians (eleven anesthesiologists and five surgeons) throughout Ontario wererecruited. An interview guide based on the TDF was developed to identify beliefs about preoperativetesting practices. Content analysis of physicians' statements into the relevanttheoretical domains was performed. Specific beliefs were identified by grouping similarutterances of the interview participants. Relevant domains were identified by noting thefrequencies of the beliefs reported, presence of conflicting beliefs, and perceived influence onthe performance of the behaviour under investigation. RESULTS: Seven of the twelve domains were identified as likely relevant to changing clinicians'behaviour about pre-operative test ordering for anesthesia management. Key beliefs wereidentified within these domains including: conflicting comments about who was responsiblefor the test-ordering (Social/professional role and identity); inability to cancel tests orderedby fellow physicians (Beliefs about capabilities and social influences); and the problem withtests being completed before the anesthesiologists see the patient (Beliefs about capabilitiesand Environmental context and resources). Often, tests were ordered by an anesthesiologistbased on who may be the attending anesthesiologist on the day of surgery while surgeonsordered tests they thought anesthesiologists may need (Social influences). There were alsoconflicting comments about the potential consequences associated with reducing testing,from negative (delay or cancel patients' surgeries), to indifference (little or no change inpatient outcomes), to positive (save money, avoid unnecessary investigations) (Beliefs aboutconsequences). Further, while most agreed that they are motivated to reduce orderingunnecessary tests (Motivation and goals), there was still a report of a gap between theirmotivation and practice (Behavioural regulation). CONCLUSION: We identified key factors that anesthesiologists and surgeons believe influence whether theyorder pre-operative tests routinely for anesthesia management for a healthy adults undergoinglow-risk surgery. These beliefs identify potential individual, team, and organisation targetsfor behaviour change interventions to reduce unnecessary routine test ordering.     

Nitrite oxidation in the Namibian oxygen minimum zone

Nitrite oxidation is the second step of nitrification. It is the primary source of oceanic nitrate, the predominant form of bioavailable nitrogen in the ocean. Despite its obvious importance, nitrite oxidation has rarely been investigated in marine settings. We determined nitrite oxidation rates directly in ¹⁵N-incubation experiments and compared the rates with those of nitrate reduction to nitrite, ammonia oxidation, anammox, denitrification, as well as dissimilatory nitrate/nitrite reduction to ammonium in the Namibian oxygen minimum zone (OMZ). Nitrite oxidation (⩽372 nM NO₂⁻ d⁻¹) was detected throughout the OMZ even when in situ oxygen concentrations were low to non-detectable. Nitrite oxidation rates often exceeded ammonia oxidation rates, whereas nitrate reduction served as an alternative and significant source of nitrite. Nitrite oxidation and anammox co-occurred in these oxygen-deficient waters, suggesting that nitrite-oxidizing bacteria (NOB) likely compete with anammox bacteria for nitrite when substrate availability became low. Among all of the known NOB genera targeted via catalyzed reporter deposition fluorescence in situ hybridization, only Nitrospina and Nitrococcus were detectable in the Namibian OMZ samples investigated. These NOB were abundant throughout the OMZ and contributed up to ∼9% of total microbial community. Our combined results reveal that a considerable fraction of the recently recycled nitrogen or reduced NO₃⁻ was re-oxidized back to NO₃⁻ via nitrite oxidation, instead of being lost from the system through the anammox or denitrification pathways.     

Comparative Analysis of the glg Operons of Pectobacterium chrysanthemi PY35 and Other Prokaryotes

A chromosomal region of Pectobacterium chrysanthemi PY35 that contains of genes for glycogen synthesis was isolated from a cosmid library. The operon consists of glycogen branching enzyme (glgB), glycogen debranching enzyme (glgX), ADP-glucose pyrophosphorylase (glgC), glycogen synthase (glgA), and glycogen phosphorylase (glgP) genes. Gene organization is similar to that of Escherichia coli. The purified ADP-glucose pyrophosphorylase (GlgC) was activated by fructose 1,6-bisphosphate and inhibited by AMP. The constructed glgX::Omega mutant failed to integrate into the chromosome of P. chrysanthemi by marker exchange. Phylogenetic analysis based on the 16S rDNA and the amino acid sequence of Glg enzymes showed correlation with other bacteria. gamma-Proteobacteria have the glgX gene instead of the bacilli glgD gene in the glg operon. The possible evolutionary implications of the results among the prokaryotes are discussed.     

Immunomodulating activities of water-soluble exopolysaccharides obtained from submerged culture of Lentinus lepideus

Immunomodulating activities of water-soluble exopolysaccharides (LL-EX) obtained from submerged mycelial culture of Lentinus lepideus were studied and their effectiveness was compared with lipopolysaccharide (LPS). The influence of the LL-EX on macrophage cellular lysosomal enzyme activity was to stimulate up to 267%, 392%, and 464% at the level of 10, 50, and 100 mug/ml, respectively. When the LL-EX was further fractionated into LL-Fr.I and Fr.II by Sepharose CL-6B gel chromatography, the cellular lysosomal enzyme activity of LL-Fr.II (2.1- fold) was higher than Fr.I (1.2-fold). Moreover, both LL-Fr.I and Fr.II stimulated the cytokines IL-1beta, TNF-alpha, and IL-6 in macrophages. In mixed lymphocyte reaction, LL-Fr.I and Fr.II enhanced the splenocyte proliferation up to 1.2-fold and 1.4-fold (50 mg/ml), respectively, stimulating only T lymphocytes. The fractions of LL-EX not show any direct toxicity against human gastric adenocarcinoma cell (AGS). The molecular masses of LL-Fr.I and Fr.II were estimated to be about 1,986 kDa and 21 kDa, respectively. The total sugar and protein contents of the two fractions were 84.97% and 69.88% and 15.03% and 30.12%, respectively. The sugar and amino acid compositions of the LL-Fr.I and Fr.II were also analyzed in detail.     

Social capital externalities and mortality in Sweden

We conceptualize social capital as an aggregate factor affecting health production and analyze the effect of community social capital (CSC) externalities on individual mortality risk in Sweden. The study was based on a random sample from the adult Swedish population of approximately 95,000 individuals who were followed up for 4-21 years. Two municipality-level variable--registered election participation rate and registered crime rate--were used to be a proxy for CSC. The impact of CSC on mortality was estimated with an extended Cox model, controlling for the initial health status and a number of individual characteristics. The results indicate that both proxies of CSC were associated with individual risk from all-cause mortality for males older than 65+ (p=0.013 and p=0.008) but not for females. A higher election participation rate negatively and significantly associated with the mortality risk from cancer for males (p=0.007), and may also have exerted protective associations for cardiovascular mortality (p=0.134) and deaths due to "suicide" (p=0.186) or "other external causes" (p=0.055). Similar associations were observed for the crime rate variable. The findings were robust to alternative specifications examined in the sensitivity analysis.     

cAMP-dependent protein kinase A (PKA) signaling induces TNFR1 exosome-like vesicle release via anchoring of PKA regulatory subunit RIIbeta to BIG2

The 55-kDa TNFR1 (type I tumor necrosis factor receptor) can be released to the extracellular space by two mechanisms, the proteolytic cleavage and shedding of soluble receptor ectodomains and the release of full-length receptors within exosome-like vesicles. We have shown that the brefeldin A-inhibited guanine nucleotide exchange protein BIG2 associates with TNFR1 and selectively modulates the release of TNFR1 exosome-like vesicles via an ARF1- and ARF3-dependent mechanism. Here, we assessed the role of BIG2 A kinase-anchoring protein (AKAP) domains in the regulation of TNFR1 exosome-like vesicle release from human vascular endothelial cells. We show that 8-bromo-cyclic AMP induced the release of full-length, 55-kDa TNFR1 within exosome-like vesicles via a protein kinase A (PKA)-dependent mechanism. Using RNA interference to decrease specifically the levels of individual PKA regulatory subunits, we demonstrate that RIIbeta modulates both the constitutive and cAMP-induced release of TNFR1 exosome-like vesicles. Consistent with its AKAP function, BIG2 was required for the cAMP-induced PKA-dependent release of TNFR1 exosome-like vesicles via a mechanism that involved the binding of RIIbeta to BIG2 AKAP domains B and C. We conclude that both the constitutive and cAMP-induced release of TNFR1 exosome-like vesicles occur via PKA-dependent pathways that are regulated by the anchoring of RIIbeta to BIG2 via AKAP domains B and C. Thus, BIG2 regulates TNFR1 exosome-like vesicle release by two distinct mechanisms, as a guanine nucleotide exchange protein that activates class I ADP-ribosylation factors and as an AKAP for RIIbeta that localizes PKA signaling within cellular TNFR1 trafficking pathways.     

Rural-urban migration and child survival in urban Bangladesh: are the urban migrants and poor disadvantaged?

This paper analyses the levels and trends of childhood mortality in urban Bangladesh, and examines whether children's survival chances are poorer among the urban migrants and urban poor. It also examines the determinants of child survival in urban Bangladesh. Data come from the 1999-2000 Bangladesh Demographic and Health Survey. The results indicate that, although the indices of infant and child mortality are consistently better in urban areas, the urban-rural differentials in childhood mortality have diminished in recent years. The study identifies two distinct child morality regimes in urban Bangladesh: one for urban natives and one for rural-urban migrants. Under-five mortality is higher among children born to urban migrants compared with children born to life-long urban natives (102 and 62 per 1000 live births, respectively). The migrant-native mortality differentials more-or-less correspond with the differences in socioeconomic status. Like childhood mortality rates, rural-urban migrants seem to be moderately disadvantaged by economic status compared with their urban native counterparts. Within the urban areas, the child survival status is even worse among the migrant poor than among the average urban poor, especially recent migrants. This poor-non-poor differential in childhood mortality is higher in urban areas than in rural areas. The study findings indicate that rapid growth of the urban population in recent years due to rural-to-urban migration, coupled with higher risk of mortality among migrant's children, may be considered as one of the major explanations for slower decline in under-five mortality in urban Bangladesh, thus diminishing urban-rural differentials in childhood mortality in Bangladesh. The study demonstrates that housing conditions and access to safe drinking water and hygienic toilet facilities are the most critical determinants of child survival in urban areas, even after controlling for migration status. The findings of the study may have important policy implications for urban planning, highlighting the need to target migrant groups and the urban poor within urban areas in the provision of health care services.