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Different types of house dust samples are widely used as surrogates of airborne inhalation exposure in studies assessing health effects of indoor microbes. Here we studied—in a quantitative assessment—the representativeness of different house dust samples of indoor air (IA) and investigated seasonality and reproducibility of indoor samples. Microbial exposure was measured five times over 1 year in four rural and five urban Finnish homes. Six sampling methods were used: button inhalable aerosol sampler (actively collected personal and indoor air sampling), settled dust, floor dust, mattress dust and vacuum cleaner dust bag dust; the latter three referred to herein as “reservoir dust samples”. Using quantitative PCR, we quantified the fungal species Cladosporium herbarum, the fungal group Penicillium/Aspergillus/Paecilomyces variotii, total fungal DNA, and Gram-positive and Gram-negative bacteria. We observed significant differences in microbial levels between rural and urban homes, most pronounced for personal air samples. Fungal species and groups but not total fungal DNA in indoor air correlated moderately to well with reservoir dust and with personal air samples. For bacterial groups, the correlations between air and dust were generally lower. Samples of indoor air and settled dust reflected similarly seasonal variation in microbial levels and were also similar compositionally, as assessed by ratios of qPCR markers. In general, determinations from mattress dust and other reservoir samples were better reproducible in repeated assessments over time than from indoor air or settled dust. This study indicates that settled dust reflects the microbial composition of indoor air and responds similarly to environmental determinants. Reservoir dusts tend to predict better microbial levels in indoor air and are more reproducible. Sampling strategies in indoor studies need to be developed based on the study questions and may need to rely on more than one type of sample.

Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from the paleohexaploid event were enriched for transcriptional regulation, whereas tandem duplicates were overrepresented by environmental responses. Population resequencing of 80 individuals showed effective population size crashes at major points of climatic upheaval. Selective sweeps were enriched among polyploid duplicates encoding key developmental and physiological triggering functions, suggesting that local adaptation has tuned the timing of and cross-talk between fundamental plant processes. Variation around the tightly-linked light response genes PHYC and FRS10 correlated with latitude and longitude and temperature, and with precipitation for PHYC. Similar associations characterized the growth-promoting cytokinin response regulator ARR1, and the wood development genes KAK and MED5A.

Nonlinear optical (NLO) activity of a molecule in general is connected to fundamental issues like charge transfer, conjugation, polarization, and recently suggested and less investigated diradical character. Extensively studied molecules for negative second order hyperpolarizabilities are the centrosymmetric squaraine derivatives (SQ) which have absorption in the region greater than 600 nm. These have no formal electronic structure but can be represented as a mixture of zwitterionic and diradicaloid valence bond resonance structures. In this work we have designed and synthesized arylamino SQ, 1−10, which bias the valence bond resonance picture completely to the zwitterionic type and totally eliminates the diradicaloid contribution (estimated using computational studies to be zero). Due to this, the lowest energy transitions are blue-shifted to the region less than 500 nm. We have carried out degenerate four wave mixing (DFWM) studies for estimation of γ values of these molecules using a 800 nm wavelength laser. The γ values are measured under nonresonant conditions and also at intensities where two photon absorption does not play any role. Nonlinear absorption properties of these molecules are studied through Z scan technique. The γ values, though smaller than the SQ having absorption in the red region, are reasonably large and range from −1.2 to −6.9 × 10−33esu. High level computational techniques and model molecules have been utilized to understand the transition and the NLO activity in these molecules.

Background/aimThe immune system and gut microbiota may play a role in the cognitive development. The home microbiota are a source of microbial exposure affecting immunological and maybe gut microbiota development. Thus, it may contribute to cognitive development. Here, we assess the association between early life home dust microbial diversity and hyperactivity/inattention symptoms at 10 and 15 years old.MethodsA random sample enriched with subjects with hyperactivity/inattention at age 15 years were selected from the German LISA birth cohort. Bedroom floor dust samples were collected at age 3 months and bacterial diversity was defined by richness (number of OTUs and Chao1) and diversity indices (Shannon and Simpson) calculated from Illumina MiSeq sequencing data of 16S rRNA gene DNA amplicons. Hyperactivity/inattention was defined based on the scores of the Strengths and Difficulties questionnaire (SDQ) at ages 10 (filled by parents) and at 15 years (self-administered), using a cut-off ≥7. With adjusted logistic regression models we investigate the associations between symptoms and 4 diversity indices in tertiles. At age 10, models were weighted by the inverse of the sampling weights.ResultsWe included 226 individuals with information on indoor microbial diversity and hyperactivity/inattention symptoms. The median values of the diversity indices were higher among children without symptoms at age 10 for bacteria and at age 15 for fungi. After adjustment, hyperactivity/inattention at age 10 was inversely associated with bacterial richness (number of observed OTUs medium vs low diversity: OR=0.4; CI: 0.2 to 0.8; Chao1 medium vs low diversity: OR=0.3; CI: 0.1 to 0.5; high vs low: OR=0.3; CI: 0.2 to 0.6), and positively associated with fungal Chao1 (high vs low: OR=2.1; CI: 1.1 to 4.0), Shannon (medium vs low: OR=2.8; CI: 1.3 to 5.8), and Simpson (high vs low: OR=4.7; CI: 2.4 to 9.3). No significant associations were observed between the indices and hyperactivity/inattention at age 15.ConclusionOur results suggest that early life exposure to microbial diversity may play a role in the development of hyperactivity/inattention during childhood. Exposure to rich bacterial environment may protect from developing hyperactivity/inattention, while high fungal diversity may have the opposite effect. Further larger studies are needed to confirm our results.