External and internal detection of Nosema ceranae on honey bees using real-time PCR

Numerous methods exist for molecular-based detection of Nosema ceranae. Here we determine location of parasite loads, the optimal tissue for pathogen detection, and the likely sources of variability among assays. Bee washes and head/thorax samples revealed substantial N. ceranae loads (2.67×10(4)±1.12×10(4) and 1.83×10(4)±4.14×10(3)). Midgut samples carried the highest parasite loads (3.42×10(6)±1.84×10(6)), followed by the hindgut (5.50×10(5)±3.24×10(5)). We recommend using midgut samples for molecular-based detection and quantification of N. ceranae because of the low variability among samples.     

Munc18c provides stimulus-selective regulation of GLUT4 but not fatty acid transporter trafficking in skeletal muscle

Insulin-, and contraction-induced GLUT4 and fatty acid (FA) transporter translocation may share common trafficking mechanisms. Our objective was to examine the effects of partial Munc18c ablation on muscle glucose and FA transport, FA oxidation, GLUT4 and FA transporter (FAT/CD36, FABPpm, FATP1, FATP4) trafficking to the sarcolemma, and FAT/CD36 to mitochondria. In Munc18c(-/+) mice, insulin-stimulated glucose transport and GLUT4 sarcolemmal appearance were impaired, but were unaffected by contraction. Insulin- and contraction-stimulated FA transport, sarcolemmal FA transporter appearance, and contraction-mediated mitochondrial FAT/CD36 were increased normally in Munc18c(-/+) mice. Hence, Munc18c provides stimulus-specific regulation of GLUT4 trafficking, but not FA transporter trafficking.     

Regulation of the epithelial sodium channel by serine proteases in human airways.

The epithelial sodium channel (ENaC) constitutes the rate-limiting step for sodium absorption across airway epithelia, which in turn regulates airway surface liquid (ASL) volume and the efficiency of mucociliary clearance. This role in ASL volume regulation suggests that ENaC activity is influenced by local factors rather than systemic signals indicative of total body volume homeostasis. Based on reports that ENaC may be regulated by extracellular serine protease activity in Xenopus and mouse renal epithelia, we sought to identify proteases that serve similar functions in human airway epithelia. Homology screening of a human airway epithelial cDNA library identified two trypsin-like serine proteases (prostasin and TMPRSS2) that, as revealed by in situ hybridization, are expressed in airway epithelia. Functional studies in the Xenopus oocyte expression system demonstrated that prostasin increased ENaC currents 60--80%, whereas TMPRSS2 markedly decreased ENaC currents and protein levels. Studies of primary nasal epithelial cultures in Ussing chambers revealed that inhibition of endogenous serine protease activity with aprotinin markedly decreased ENaC-mediated currents and sensitized the epithelia to subsequent channel activation by exogenous trypsin. These data, therefore, suggest that protease-mediated regulation of sodium absorption is a function of human airway epithelia, and prostasin is a likely candidate for this activity.     

Inhibition of corticosteroid 11 beta hydroxylation in bovine zona fasciculata cells by the potassium entry blocker 4-aminopyridine

The potassium entry blocker, 4-aminopyridine has been used to evaluate the importance of this cation in several tissues including the adrenal cortex. Since it inhibited corticosteroidogenesis, an important role for potassium entry in the control of this process has been implied. In the present in vitro study, 4-aminopyridine inhibited cortisol and corticosterone production and, at high concentrations, that of 11-deoxycortisol and 11-deoxycorticosterone. However, at lower concentrations, 11-deoxycorticosteroid production increased suggesting that 4-aminopyridine acts as an inhibitor of 11 beta hydroxylation. Its slight resemblance to metyrapone may suggest that it acts, at least in part, by competing for cytochrome P450. However, its use as a potassium inhibitor in studies of the adrenal cortex may give ambiguous results.     

Control of Pyrimidine Biosynthesis in Pseudomonas aeruginosa

The pathway of pyrimidine biosynthesis in Pseudomonas aeruginosa has been shown to be the same as in other bacteria. Twenty-seven mutants requiring uracil for growth were isolated and the mutant lesions were identified. Mutants lacking either dihydroorotic acid dehydrogenase, orotidine monophosphate pyrophosphorylase, orotidine monophosphate decarboxylase, or aspartic transcarbamylase were isolated; none lacking dihydroorotase were found. By using transduction and conjugation, four genes affecting pyrimidine biosynthetic enzymes have been identified and shown to be unlinked to each other. The linkage of pyrB to met-28 and ilv-2 was shown by contransduction. Repression by uracil alone or by broth could not be demonstrated for any enzymes of this pathway, in contrast to the situation in Escherichia coli and Serratia marcescens. In addition, derepression of these enzymes could not be demonstrated. A low level of feedback inhibition of aspartic transcarbamylase was found to occur. It is suggested that the control of such constitutive biosynthetic enzymes in P. aeruginosa may be related to the comprehensive metabolic activities of this organism.     

Climate Change and Heat-Related Excess Mortality in the Eastern USA

Climate change will increase extreme heat-related health risks. To quantify the health impacts of mid-century climate change, we assess heat-related excess mortality across the eastern USA. Health risks are estimated using the US Environmental Protection Agency’s Environmental Benefits Mapping and Analysis Program (BenMAP). Mid-century temperature estimates, downscaled using the Weather Research and Forecasting model, are compared to 2007 temperatures at 36 km and 12 km resolutions. Models indicate the average apparent and actual summer temperatures rise by 4.5° and 3.3° C, respectively. Warmer average apparent temperatures could cause 11,562 additional annual deaths (95% confidence interval, CI: 2641–20,095) due to cardiovascular stress in the population aged 65 years and above, while higher minimum temperatures could cause 8767 (95% CI: 5030–12,475) additional deaths each year. Modeled future climate data available at both coarse (36 km) and fine (12 km) resolutions predict significant human health impacts from warmer climates. The findings suggest that currently available information on future climates is sufficient to guide regional planning for the protection of public health. Higher resolution climate and demographic data are still needed to inform more targeted interventions.     

Place,scale and the racial claims made for multiracial children in the 1990 US Census

Multiracial children embody ambiguities inherent in racial categorization and expose fictions of discrete races. Nevertheless, parents of multiracial children were asked for the 1990 US Census to report a single race for their offspring. Using confidential 1990 Census micro-data, we investigate the choices parents made for the three most common racially mixed household types (Asian-white, black-white and Latino-white) in twelve large metropolitan areas. We find that context affects the reporting of children's racial identity. We examine these effects with models that incorporate three spatial scales: households, neighbourhoods and metropolitan areas. Model estimates reveal that racial claims made by parents of Latino- and Asian-white (but not black-white) children varied significantly across metropolitan area. A neighbourhood's proportion white increased the probability that parents reported their children as white, while a neighbourhood's racial diversity increased the probability that black-white parents claimed a non-white race (black or ‘other’) for their children.     

Phenotypic and Genetic Analyses of the Varroa Sensitive Hygienic Trait in Russian Honey Bee (Hymenoptera: Apidae) Colonies

Varroa destructor continues to threaten colonies of European honey bees. General hygiene, and more specific Varroa Sensitive Hygiene (VSH), provide resistance towards the Varroa mite in a number of stocks. In this study, 32 Russian (RHB) and 14 Italian honey bee colonies were assessed for the VSH trait using two different assays. Firstly, colonies were assessed using the standard VSH behavioural assay of the change in infestation of a highly infested donor comb after a one-week exposure. Secondly, the same colonies were assessed using an “actual brood removal assay” that measured the removal of brood in a section created within the donor combs as a potential alternative measure of hygiene towards Varroa-infested brood. All colonies were then analysed for the recently discovered VSH quantitative trait locus (QTL) to determine whether the genetic mechanisms were similar across different stocks. Based on the two assays, RHB colonies were consistently more hygienic toward Varroa-infested brood than Italian honey bee colonies. The actual number of brood cells removed in the defined section was negatively correlated with the Varroa infestations of the colonies (r² = 0.25). Only two (percentages of brood removed and reproductive foundress Varroa) out of nine phenotypic parameters showed significant associations with genotype distributions. However, the allele associated with each parameter was the opposite of that determined by VSH mapping. In this study, RHB colonies showed high levels of hygienic behaviour towards Varroa -infested brood. The genetic mechanisms are similar to those of the VSH stock, though the opposite allele associates in RHB, indicating a stable recombination event before the selection of the VSH stock. The measurement of brood removal is a simple, reliable alternative method of measuring hygienic behaviour towards Varroa mites, at least in RHB stock.     

A novel yeast mutant that is defective in regulation of the Anaphase-Promoting Complex by the spindle damage checkpoint

The accurate segregation of sister chromatids at the metaphase to anaphase transition in Saccharomyces cerevisiae is regulated by the activity of the anaphase-promoting complex or cyclosome (APC/C). In the event of spindle damage or monopolar spindle attachment, the spindle checkpoint is activated and inhibits APC/C activity towards the anaphase inhibitor Pds1p, resulting in a cell cycle arrest at metaphase. We have identified a novel allele of a gene for an APC/C subunit, cdc16-183 , in S. cerevisiae. cdc16-183 mutants arrest at metaphase at 37°C, and are supersensitive to the spindle-damaging agent nocodazole, which activates the spindle checkpoint, at lower temperatures. This supersensitivity to nocodazole cannot be explained by impairment of the spindle checkpoint pathway, as cells respond normally to spindle damage with a stable metaphase arrest and high levels of Pds1p. Despite showing metaphase arrest at G2/M at 37°C, cdc16-183 mutants are able to perform tested G1 functions normally at this temperature. This is the first demonstration that a mutation in a core APC/C subunit can result in a MAD2-dependent arrest at the restrictive temperature. Our results suggest that the cdc16-183 mutant may have a novel APC/C defect(s) that mimics or activates the spindle checkpoint pathway.Communicated by C. P. Hollenberg