Association between childhood asthma and ADHD symptoms in adolescence : a prospective population-based twin study

BACKGROUND: Cross-sectional studies report a relationship between childhood asthma and attention-deficit hyperactivity disorder (ADHD) symptoms, but the mechanisms are yet unclear. Our objective was to investigate the longitudinal link between childhood asthma and the two dimensions of ADHD (hyperactivity-impulsivity, HI, and inattention, IN) in adolescence. We also aimed to explore the genetic and environmental contributions and the impact of asthma medication. METHODS: Data on asthma, HI and IN, birth weight, socioeconomic status, zygosity, and medication were collected from the Swedish Medical Birth Register and through parental questionnaires at ages 8-9 and 13-14 years on 1480 Swedish twin pairs born 1985-1986. The association between asthma at age 8-9 and ADHD symptoms at age 13-14 was assessed with generalized estimating equations, and twin analyses to assess the genetic or environmental determinants were performed. RESULTS: Children with asthma at age 8-9 had an almost twofold increased risk of having one or more symptom of HI (OR 1.88, 95% CI 1.18-3.00) and a more than twofold increased risk to have three symptoms or more of HI (OR 2.73, 95% CI 1.49-5.00) at age 13-14, independent of asthma medication. For IN, no significant relationship was seen. Results from twin modeling indicate that 68% of the phenotypic correlation between asthma and HI (r=0.23, 0.04-0.37) was because of genetic influences. CONCLUSIONS: Our findings suggest that childhood asthma is associated with subsequent development of HI in early adolescence, which could be partly explained by genetic influences. Early strategies to identify children at risk may reduce burden of the disease in adolescence.VRALFThe Centre for Allergy ResearchThe Strategic Research Program in Epidemiology at Karolinska Institutet.Manuscrip

Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by 20-50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20-37% compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population

Phytoplankton growth after a century of dormancy illuminates past resilience to catastrophic darkness

Photosynthesis evolved in the oceans more than 3 billion years ago and has persisted throughout all major extinction events in Earth's history. The most recent of such events is linked to an abrupt collapse of primary production due to darkness following the Chicxulub asteroid impact 65.5 million years ago. Coastal phytoplankton groups (particularly dinoflagellates and diatoms) appear to have been resilient to this biotic crisis, but the reason for their high survival rates is still unknown. Here we show that the growth performance of dinoflagellate cells germinated from resting stages is unaffected by up to a century of dormancy. Our results clearly indicate that phytoplankton resting stages can endure periods of darkness far exceeding those estimated for the Cretaceous-Paleogene extinction and may effectively aid the rapid resurgence of primary production in coastal areas after events of prolonged photosynthesis shut-down

Phytoplankton Community Dynamic: A Driver for Ciliate Trophic Strategies

Phytoplankton plays a key role as primary producers and mediating biogeochemical cycles in the water column. The understanding of the temporal dynamic of primary grazers channeling energy and carbon from primary producers is important for evaluating aquatic ecosystems functioning. This study investigates the coupling between phytoplankton and ciliates from live samples collected with approximately daily frequency during an almost 2-year cycle. The study site is a nutrient-rich temperate estuary, Roskilde Fjord (Denmark). Our aim is to evaluate the importance of protist grazers, especially ciliates, as predators on phytoplankton and to evaluate differences among multiple nutritional strategies through different seasons. The phytoplankton community, was mostly dominated by small organisms (<20 μm) with few observations of diatoms. In most of observations, heterotrophic dinoflagellates biomass was smaller than biomass of ciliates (<10%), indicating that ciliates are the main component of microzooplankton. Except for the spring 2016, the ciliate community closely followed the phytoplankton community, showing a tight coupling between the primary producers and grazers during all seasons. This somehow contradicts the general assumption that ciliate dominance is restricted to periods of nutrient limitation dominated by the microbial food web and suggests a year-round key role of ciliates as consumers of phytoplankton biomass. Biomasses of ciliates increased during spring and were highest during summer. Relative importance of mixotrophs were high due to occurrence of Mesodinium rubrum blooms as well as other mixotrophic ciliates in late spring/early summer. M. rubrum biomass had the opposite pattern of the cryptophyte prey Teleaulax spp., and the coupling between the two populations was very strong in late spring. Ciliates that grazed on selected phytoplankton, had a smaller potential grazing impact regarding their biomasses, likely due to food limitation; conversely ciliates that feed on diverse prey items were less constrained by food limitation, and their seasonality appear to be driven by other factors. These findings suggest that the ciliate community structure and dynamics is important in structuring the phytoplankton community on short and seasonal scale

Pseudo-nitzschia Peragallo (Bacillariophyceae) diversity and domoic acid accumulation in tuberculate cockles and sweet clams in M’diq Bay, Morocco

The diversity of Pseudo-nitzschia (Bacillariophyceae) and accumulation of the neurotoxin domoic acid (DA) in two types of shellfish; tuberculate cockles (Acanthocardia tuberculata) and sweet clams (Challista chione) was explored in M’diq Bay,Morocco during 2007. The highest abundances of Pseudo-nitzschia were found during the period from March to October, with peaks occurring in May and September. Toxin analysis showed an accumulation of domoic acid in shellfish sampled during spring and autumn. The maximum toxin concentration was 4.9 mg DAg–1 of the whole tissue recorded in sweet clam during spring. Using transmission electron microscopy, thirteen Pseudo-nitzschia species were identified, eight of which are known as producers of domoic acid: P. multistriata, P. cuspidata, P. galaxiae, P. multiseries, P. pseudodelicatissima, P. pungens var. aveirensis, P. calliantha and P. fraudulenta. The five non- toxic species observed were P. subpacifica, P. arenysensis, P. dolorosa, P. subfraudulenta, and P. cf. caciantha

Transfer of the Antarctic diatom Nitzschia barbieri (Bacillariophyta) to the genus Fragilariopsis and emended descriptions of F. barbieri comb. nov. and F. peragallii

Fragilariopsis is a marine diatom genus that has a critical ecological role in Antarctic waters due to its high abundance and ubiquity in plankton and sea ice. Several species of Fragilariopsis are used extensively in paleoceanography due to their good preservation in marine sediments. Detailed morphological studies on Fragilariopsis species from Antarctic water and ice samples were thus performed. Nevertheless, some species of this genus still remain poorly studied. Based on close morphological similarity between the valve structure of the Antarctic diatom Nitzschia barbieri and the genus Fragilariopsis, we propose transferring N. barbieri to Fragilariopsis as Fragilariopsis barbieri comb. nov. The description of the two rarely reported species, F. barbieri and F. peragallii, were emended. The girdle structure and the formation of doublets in F. barbieri and F. peragallii are described and illustrated for the first time. The analyses were carried out by light and electron microscopy and complete the morphological description of the fourteen known extant taxa of Fragilariopsis from Antarctica. Relative abundance of Fragilariopsis species from sea ice is also presented.Facultad de Ciencias Naturales y Muse

Semicryptic Diversity around Chaetoceros elegans (Bacillariophyta, Mediophyceae), and the Description of Two New Species

The globally distributed Chaetoceros elegans belongs to the Chaetoceros lorenzianus (C. lorenzianus) complex and is characterized by having tear-shaped setae poroids. Several strains of C. elegans were established from Chinese coastal waters. The vegetative cells and the resting spores were observed using light and electron microscopy. Phylogenetic analyses of two nuclear ribosomal RNA genes (SSU and the D1–D3 region of LSU) and the internal transcribed spacer (ITS) revealed that the C. elegans strains clustered into three clades, corresponding to different morphotypes. Based on the type material, the delineation of C. elegans was amended, and two new taxa, (Chaetoceros macroelegans) C. macroelegans sp. nov. and (Chaetoceros densoelegans) C.densoelegans sp. nov., were described. The two new taxa are featured by the presence of two types of setae poroids, tear-shaped and round-oval setae poroids, whereas only tear-shaped setae poroids are seen in C. elegans. The setae base is distinct in C. elegans, but absent or short in the two new taxa. In C. macroelegans, the tear-shaped poroids on the intercalary setae are larger and less densely spaced than in the other two species. The round-oval setae poroids are more densely spaced in C.densoelegans than in C. macroelegans, although they have more or less the same size. Resting spores characterize the two new taxa, but are unknown in the amended C. elegans. When comparing the ITS2 secondary structure, two and four compensatory base changes (CBCs) distinguish C. elegans from C. macroelegans and C.densoelegans, respectively. Between the two new taxa, no CBC but five hemi-CBCs (HCBCs) are present. The shape, size and density of the setae poroids, as well as the morphology of the resting spores, are important characteristics for species identification among the presently nine known species within the C. lorenzianus complex. View Full-Tex