Measurement of the nucleation of atmospheric aerosol particles

The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.     

The TREX1 double-stranded DNA degradation activity is defective in dominant mutations associated with autoimmune disease

Mutations in TREX1 have been linked to a spectrum of human autoimmune diseases including Aicardi-Goutières syndrome (AGS), familial chilblain lupus (FCL), systemic lupus erythematosus, and retinal vasculopathy and cerebral leukodystrophy. A common feature in these conditions is the frequent detection of antibodies to double-stranded DNA (dsDNA). TREX1 participates in a cell death process implicating this major 3' --> 5' exonuclease in genomic DNA degradation to minimize potential immune activation by persistent self DNA. The TREX1 D200N and D18N dominant heterozygous mutations were identified in AGS and FCL, respectively. TREX1 enzymes containing the D200N and D18N mutations were compared using nicked dsDNA and single-stranded DNA (ssDNA) degradation assays. The TREX1WT/D200N and TREX1WT/D18N heterodimers are completely deficient at degrading dsDNA and degrade ssDNA at an expected approximately 2-fold lower rate than TREX1WT enzyme. Further, the D200N- and D18N-containing TREX1 homo- and heterodimers inhibit the dsDNA degradation activity of TREX1WT enzyme, providing a likely explanation for the dominant phenotype of these TREX1 mutant alleles in AGS and FCL. By comparison, the TREX1 R114H homozygous mutation causes AGS and is found as a heterozygous mutation in systemic lupus erythematosus. The TREX1R114H/R114H homodimer has dysfunctional dsDNA and ssDNA degradation activities and does not detectibly inhibit the TREX1WT enzyme, whereas the TREX1WT/R114H heterodimer has a functional dsDNA degradation activity, supporting the recessive genetics of TREX1 R114H in AGS. The dysfunctional dsDNA degradation activities of these disease-related TREX1 mutants could account for persistent dsDNA from dying cells leading to an aberrant immune response in these clinically related disorders.     

Anaerobic digestion of grass silage in batch leach bed processes for methane production

Anaerobic digestion of grass silage in batch leach bed reactors, with and without a second stage upflow anaerobic sludge blanket (UASB) reactor, was evaluated. Sixty six percent of the methane potential in grass was obtained within the 55 days solids retention time in the leach bed-UASB process without pH adjustment, whereas in the one-stage leach bed process 20% of the methane potential in grass was extracted. In two-stage operation, adjustment of the pH of influent to the leach bed reactor to 6 with HCl led to inhibition of both hydrolysis/acidogenesis and methanogenesis. In the leach bed-UASB process 39% of the carbohydrates and 58% of the acid soluble lignin were solubilised within the 49 days of operation, whereas Klason lignin was most recalcitrant. The methane potential of the digestates varied from 0.141 to 0.204 m3 CH4 kg(-1) added volatile solids.     

Presence of the Chytrid Fungus Batrachochytrium dendrobatidis in Populations of the Critically Endangered Frog Mannophryne olmonae in Tobago, West Indies

The emerging infectious disease chytridiomycosis is prevalent in Central and South America, and has caused catastrophic declines of amphibian populations in the Neotropics. The responsible organism, Batrachochytrium dendrobatidis, has been recorded on three West Indian islands, but the whole of the Caribbean region is predicted to offer a suitable environment for the disease. Monitoring the spread of chytridiomycosis is thus a priority in this region, which has exceptionally high levels of amphibian endemism. PCR analysis of 124 amphibian skin swabs in Tobago (Republic of Trinidad and Tobago) demonstrated the presence of B. dendrobatidis in three widely separated populations of the frog Mannophryne olmonae, which is listed as Critically Endangered on the basis of recent population declines. Chytridiomycosis is presently endemic in this species, with a prevalence of about 20% and no associated clinical disease. Increased susceptibility to chytridiomycosis from climate change is unlikely in amphibian populations in Tobago, as this island does not have high montane environments, but remains a possibility in the sister island of Trinidad. Preventing the spread of chytridiomycosis within and between these and other Caribbean islands should be a major goal of practical conservation measures for amphibians in the region.     

Multiple Dimensions of Socioeconomic Position and Obesity among Employees: The Helsinki Health Study

Objective: To examine socioeconomic differences in obesity using several different socioeconomic indicators, ranging from childhood socioeconomic environment and adult socioeconomic status to material resources and economic satisfaction. Research Methods and Procedures: The data derived from the Helsinki Health Study baseline surveys in 2000 and 2001. Respondents to postal surveys were middle‐aged employees of the City of Helsinki (4, 975 women and 1, 252 men, response rate 68%). Associations between eight socioeconomic indicators and obesity (BMI ≥ 30 kg/m²), calculated from self‐reported data, were examined by fitting a series of logistic regression models. Results: In women, all socioeconomic indicators except household income and economic satisfaction were associated with obesity. Parental education and childhood economic difficulties, i.e., socioeconomic conditions in childhood, remained associated with obesity after adjusting for all indicators of current socioeconomic position. Indicators of adult socioeconomic status, own education and occupational class, were no longer associated with obesity when childhood socioeconomic conditions were adjusted for. Home ownership and economic difficulties were associated with obesity after full adjustments. In men, the findings paralleled those among women, but few associations reached statistical significance. Discussion: Obesity was associated with several dimensions of socioeconomic position. Childhood socioeconomic disadvantage was associated with obesity independently of the various indicators of current socioeconomic position. Associations between obesity and both educational level and occupational class disappeared after adjustment for other indicators of socioeconomic position. This suggests that the variation observed in the prevalence of obesity by these key socioeconomic indicators may reflect differences in the related material resources.     

Forest floor vegetation response to nitrogen deposition in Europe

Chronic nitrogen (N) deposition is a threat to biodiversity that results from the eutrophication of ecosystems. We studied long‐term monitoring data from 28 forest sites with a total of 1,335 permanent forest floor vegetation plots from northern Fennoscandia to southern Italy to analyse temporal trends in vascular plant species cover and diversity. We found that the cover of plant species which prefer nutrient‐poor soils (oligotrophic species) decreased the more the measured N deposition exceeded the empirical critical load (CL) for eutrophication effects (P = 0.002). Although species preferring nutrient‐rich sites (eutrophic species) did not experience a significantly increase in cover (P = 0.440), in comparison to oligotrophic species they had a marginally higher proportion among new occurring species (P = 0.091). The observed gradual replacement of oligotrophic species by eutrophic species as a response to N deposition seems to be a general pattern, as it was consistent on the European scale. Contrary to species cover changes, neither the decrease in species richness nor of homogeneity correlated with nitrogen CL exceedance (ExCL_empN). We assume that the lack of diversity changes resulted from the restricted time period of our observations. Although existing habitat‐specific empirical CL still hold some uncertainty, we exemplify that they are useful indicators for the sensitivity of forest floor vegetation to N deposition.     

Gene defect in hypodontia: exclusion of MSX1 and MSX2 as candidate genes

Hypodontia, congenital lack of one or a few teeth, is an autosomally inherited dominant trait. Homeobox genes MSX1 and MSX2 are expressed in presumptive dental tissues at the stage of initiation of tooth development. Recently, tooth development was shown to be inhibited in transgenic mice lacking a functional Msx1 gene. Here, we studied the relationship of the MSX1 and MSX2 genes to familial hypodontia in five Finnish families with a total of 20 affected individuals, by linkage analysis. The pairwise lod-scores regarding the intragenic microsatellites in the MSX1 and MSX2 genes at a recombination fraction of 0.0 were -3.1 and -3.0, respectively, thus excluding these genes as causative loci for hypodontia in these families.