Biological pollution and its relationship with respiratory symptoms indicative of asthma, Bucaramanga, Colombia

Introduction. Indoorair pollution may play an important role in development and exacerbation of asthma in children. Objective. The association between the presence of indoor biological contaminants and respiratory symptoms related to asthma was assessed in preschool children. Materials and methods. This cross-sectional study was undertaken in Bucaramanga, Colombia, and included children <7 years of age living in two urban areas of with different levels of outdoor air pollution. The 678 children were an average of 3.5 years of age. Respiratory symptoms indicative of asthma and indoor air pollutants were assessed by previously validated questionnaires.. Biological samples potentially containing mites and fungi were collected by standardized laboratory methods. The log binomial regression model was used for multivariate analysis, using adjusted prevalence ratios (PR). Results. The prevalence of asthmatic respiratory symptoms was 8.0%; (95% C.I: 5.6-9.6), without significant differences between the two areas. Binomial model analysis showed that asthma symptoms were associated with mites (PR 1.78; 95% C.I. 1.0-3.0), Acremonium sp (PR 6.24; 95 C.I.: 3.8-10.0) and a history of child pneumonia (PR 4.0; 95% C.I. 2.5-6.4), allergic rhinitis (PR 1.9; 95% C.I.: 1.2-3.1), prematurity (PR 3.4; 95% C.I. 1.8-6.5), parents with asthma (PR 2.6; 95% C.I. 1.4-5.0) and pet ownership (PR 0.4; 95% C.I. 0.2-0.9). Conclusions. The indoor exposure to biological contaminants (dust mites and fungi), history of prematurity, pneumonia, rhinitis and family history of asthma increased the occurence of symptoms suggestive of asthma in young children.     

Analysis of collagen expression during chondrogenic induction of human bone marrow mesenchymal stem cells

Adult mesenchymal stem cells (MSCs) are currently being investigated as an alternative to chondrocytes for repairing cartilage defects. As several collagen types participate in the formation of cartilage-specific extracellular matrix, we have investigated their gene expression levels during MSC chondrogenic induction. Bone marrow MSCs were cultured in pellet in the presence of BMP-2 and TGF-β3 for 24 days. After addition of FGF-2, at the fourth passage during MSC expansion, there was an enhancing effect on specific cartilage gene expression when compared to that without FGF-2 at day 12 in pellet culture. A switch in expression from the pre-chondrogenic type IIA form to the cartilage-specific type IIB form of the collagen type II gene was observed at day 24. A short-term addition of FGF-2 followed by a treatment with BMP-2/TGF-β3 appears sufficient to accelerate chondrogenesis with a particular effect on the main cartilage collagens.     

Temperature-dependent activity in early life stages of the stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae): A role for ionic and magnesium regulation?

Marine brachyuran and anomuran crustaceans are completely absent from the extremely cold (− 1.8 °C) Antarctic continental shelf, but caridean shrimps are abundant. This has at least partly been attributed to low capacities for magnesium excretion in brachyuran and anomuran lithodid crabs ([Mg²⁺]_HL = 20-50 mmol L^− 1) compared to caridean shrimp species ([Mg²⁺]_HL = 5-12 mmol L^− 1). Magnesium has an anaesthetizing effect and reduces cold tolerance and activity of adult brachyuran crabs. We investigated whether the capacity for magnesium regulation is a factor that influences temperature-dependent activity of early ontogenetic stages of the Sub-Antarctic lithodid crab Paralomis granulosa. Ion composition (Na⁺, Mg²⁺, Ca²⁺, Cl⁻, SO₄²⁻) was measured in haemolymph withdrawn from larval stages, the first and second juvenile instars (crabs I and II) and adult males and females. Magnesium excretion improved during ontogeny, but haemolymph sulphate concentration was lowest in the zoeal stages. Neither haemolymph magnesium concentrations nor Ca²⁺:Mg²⁺ ratios paralleled activity levels of the life stages. Long-term (3 week) cold exposure of crab I to 1 °C caused a significant rise of haemolymph sulphate concentration and a decrease in magnesium and calcium concentrations compared to control temperature (9 °C). Spontaneous swimming activity of the zoeal stages was determined at 1, 4 and 9 °C in natural sea water (NSW, [Mg²⁺] = 51 mmol L^− 1) and in sea water enriched with magnesium (NSW + Mg²⁺, [Mg²⁺] = 97 mmol L^− 1). It declined significantly with temperature but only insignificantly with increased magnesium concentration. Spontaneous velocities were low, reflecting the demersal life style of the zoeae. Heart rate, scaphognathite beat rate and forced swimming activity (maxilliped beat rate, zoea I) or antennule beat rate (crab I) were investigated in response to acute temperature change (9, 6, 3, 1, − 1 °C) in NSW or NSW + Mg²⁺. High magnesium concentration reduced heart rates in both stages. The temperature-frequency curve of the maxilliped beat (maximum: 9.6 beats s^− 1 at 6.6 °C in NSW) of zoea I was depressed and shifted towards warmer temperatures by 2 °C in NSW + Mg²⁺, but antennule beat rate of crab I was not affected. Magnesium may therefore influence cold tolerance of highly active larvae, but it remains questionable whether the slow-moving lithodid crabs with demersal larvae would benefit from an enhanced magnesium excretion in nature.     

Development of a genetic system for Marinobacter adhaerens HP15 involved in marine aggregate formation by interacting with diatom cells

Diatom aggregation is substantial for organic carbon flux from the photic zone to deeper waters. Many heterotrophic bacteria ubiquitously found in diverse marine environments interact with marine algae and thus impact organic matter and energy cycling in the ocean. In particular, Marinobacter adhaerens HP15 induces aggregate formation while interacting with the diatom, Thalassiosira weissflogii. To study this effect at the molecular level, a genetic tool system was developed for strain HP15. The antibiotic susceptibility spectrum of this organism was determined and electroporation and conjugation protocols were established. Among various plasmids of different incompatibility groups, only two were shown to replicate in M. adhaerens. 1.4 × 10⁻³ transconjugants per recipient were obtained for a broad-host-range vector. Electroporation efficiency corresponded to 1.1 × 10⁵ CFU per μg of DNA. Transposon and gene-specific mutageneses were conducted for flagellum biosynthetic genes. Mutant phenotypes were confirmed by swimming assay and microscopy. Successful expression of two reporter genes in strain HP15 revealed useful tools for gene expression analyses, which will allow studying diverse bacteria-algae interactions at the molecular level and hence to gain a mechanistic understanding of micro-scale processes underlying ocean basin-scale processes. This study is the first report for the genetic manipulation of a Marinobacter species which specifically interacts with marine diatoms and serves as model to additionally analyze various previously reported Marinobacter-algae interactions in depth.     

Human perception of shape from touch

In this paper, I focus on the role of active touch in three aspects of shape perception and discrimination studies. First an overview is given of curvature discrimination experiments. The most prominent result is that first-order stimulus information (that is, the difference in attitude or slope over the stimulus) is the dominant factor determining the curvature threshold. Secondly, I compare touch under bimanual and two-finger performance with unimanual and one-finger performance. Consistently, bimanual or two-finger performance turned out to be worse. The most likely explanation for the former finding is that a loss of accuracy during intermanual comparisons is owing to interhemispheric relay. Thirdly, I address the presence of strong after-effects after just briefly touching a shape. These after-effects have been measured and studied in various conditions (such as, static, dynamic, transfer to other hand or finger). Combination of the results of these studies leads to the insight that there are possibly different classes of after-effect: a strong after-effect, caused by immediate contact with the stimulus, that does only partially transfer to the other hand, and one much less strong after-effect, caused by moving over the stimulus for a certain period, which shows a full transfer to other fingers.     

BRCC36A is epistatic to BRCA1 in DNA crosslink repair and homologous recombination in Arabidopsis thaliana

BRCA1 is a well-known tumor suppressor protein in mammals, involved in multiple cellular processes such as DNA repair, chromosome segregation and chromatin remodeling. Interestingly, homologs of BRCA1 and several of its complex partners are also found in plants. As the respective mutants are viable, in contrast to mammalian mutants, detailed analyses of their biological role is possible. Here we demonstrate that the model plant Arabidopsis thaliana harbors two homologs of the mammalian BRCA1 interaction partner BRCC36, AtBRCC36A and AtBRCC36B. Mutants of both genes as well as the double mutants are fully fertile and show no defects in development. We were able to show that mutation of one of the homologs, AtBRCC36A, leads to a severe defect in intra- and interchromosomal homologous recombination (HR). A HR defect is also apparent in Atbrca1 mutants. As the Atbrcc36a/Atbrca1 double mutant behaves like the single mutants of AtBRCA1 and AtBRCC36A both proteins seem to be involved in a common pathway in the regulation of HR. AtBRCC36 is also epistatic to AtBRCA1 in DNA crosslink repair. Upon genotoxic stress, AtBRCC36A is transferred into the nucleus.     

Thermodynamic contributions of single internal rA·dA, rC·dC, rG·dG and rU·dT mismatches in RNA/DNA duplexes

The thermodynamic contributions of rA·dA, rC·dC, rG·dG and rU·dT single internal mismatches were measured for 54 RNA/DNA duplexes in a 1 M NaCl buffer using UV absorbance thermal denaturation. Thermodynamic parameters were obtained by fitting absorbance versus temperature profiles using the curve-fitting program Meltwin. The weighted average thermodynamic data were fit using singular value decomposition to determine the eight non-unique nearest-neighbor parameters for each internal mismatch. The new parameters predict the ΔG°₃₇, ΔH° and melting temperature (T_m) of duplexes containing these single mismatches within an average of 0.33 kcal/mol, 4.5 kcal/mol and 1.4°C, respectively. The general trend in decreasing stability for the single internal mismatches is rG·dG > rU·dT > rA·dA > rC·dC. The stability trend for the base pairs 5′ of the single internal mismatch is rG·dC > rC·dG > rA·dT > rU·dA. The stability trend for the base pairs 3′ of the single internal mismatch is rC·dG > rG·dC >> rA·dT > rU·dA. These nearest-neighbor values are now a part of a complete set of single internal mismatch thermodynamic parameters for RNA/DNA duplexes that are incorporated into the nucleic acid assay development software programs Visual oligonucleotide modeling platform (OMP) and ThermoBLAST.