All about the marine/sea ice diatom Nitzschia lecointei

Generally, in terms of growth N. lecointei seems quite tolerant to changes in pH and pCO2, probably due to the fact that this species grows in an environment with large seasonal variations in the carbonate system. However, increased pCO2 resulted in physiological changes that may have important ecological consequences, such as cellular stoichiometry. For instance, we observed changes in carbon metabolism, and fatty acid content and composition, that did not affect the growth rate. When the experimental period was increased (194 days, ca. 60 asexual generations), we observed a small reduction in growth at 960 µatm pCO2 after 147 days. Carbon metabolism was significantly affected, resulting in higher cellular release of dissolved organic carbon. When studying the synergism between temperature (−1.8 and 2.5°C) and pCO2 (390 and 960 μatm), synergism was detected in growth rate and acyl lipid fatty acid content. Carbon enrichment only promoted (3 %) growth rate closer to the optimal growth, but not at the control temperature (−1.8°C). Optimal growth rate was observed around 5°C in a separate experiment. The total content of fatty acids was reduced at elevated pCO2, but only at the control temperature. PUFAs were reduced at high pCO2. When combining increased temperature and different salinity conditions, the growth rate was higher at 3°C than at -1.8°C. Salinity 10 clearly limited growth rate and the highest growth rates were found at salinity 20 and 35. In another experiment, high and low temperature together with treatments simulating ice formation and melting conditions were studied. Here, the highest levels of oxidative stress were found in low temperature and ice melting treatments, respectively. With respect to 9 weeks in the dark, cell numbers were higher at -1.5°C compared to 3°C, but when retrieved to light conditions, after one week higher cell numbers were observed at 3°C versus -1.5°C. Furthermore, cell numbers were lower when acetateUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sea-ice microbial communities in the Central Arctic Ocean: Limited responses to short-term pCO(2) perturbations

The Arctic Ocean is more susceptible to ocean acidification than other marine environments due to its weaker buffering capacity, while its cold surface water with relatively low salinity promotes atmospheric CO 2 uptake. We studied how sea-ice microbial communities in the central Arctic Ocean may be affected by changes in the carbonate system expected as a consequence of ocean acidification. In a series of four experiments during late summer 2018 aboard the icebreaker Oden, we addressed microbial growth, production of dissolved organic carbon (DOC) and extra- cellular polymeric substances (EPS), photosynthetic activity, and bacterial assemblage structure as sea-ice microbial communities were exposed to elevated partial pressures of CO 2 (pCO 2 ). We incubated intact, bottom ice-core sections and dislodged, under-ice algal aggregates (dominated by Melosira arctica) in separate experiments under approximately 400, 650, 1000, and 2000 micro atm pCO 2 for 10 d under different nutrient regimes. The results indicate that the growth of sea-ice algae and bacteria was unaffected by these higher pCO 2 levels, and concentrations of DOC and EPS were unaffected by a shifted inorganic C/N balance, resulting from the CO 2 enrichment. These central Arctic sea-ice microbial communities thus appear to be largely insensitive to short-term pCO 2 perturbations. Given the natural, seasonally driven fluctuations in the carbonate system of sea ice, its resident microorganisms may be sufficiently tolerant of large variations in pCO 2 and thus less vulnerable than pelagic communities to the impacts of ocean acidification, increasing the ecological importance of sea-ice microorganisms even as the loss of Arctic sea ice continue

Application of Control Theory to a Commercial Mobile Service Support System

The Mobile Service Support system (MSS), which Ericsson AB develops, handles the setup of new subscribers and services into a mobile network. Experience from deployed systems show that traffic monitoring and control of the system will be crucial for handling overload situations that may occur at sudden traffic surges. In this paper we identify and explore some important control challenges for this type of systems. Further, we present analysis and experiments showing some advantages of proposed solutions. First, we develop a load-dependent server model for the system, which is validated in testbed experiments. Further, we propose a control design based on the model, and a method for estimation of response times and arrival rates. The main contribution of this paper is that we show how control theory methods and analysis can be used for commercial telecom systems. Parts of our results have been implemented in commercial products, validating the strength of our work

Glacial melt disturbance shifts community metabolism of an Antarctic seafloor ecosystem from net autotrophy to heterotrophy

Climate change-induced glacial melt affects benthic ecosystems along the West Antarctic Peninsula, but current understanding of the effects on benthic primary production and respiration is limited. Here we demonstrate with a series of in situ community metabolism measurements that climate-related glacial melt disturbance shifts benthic communities from net autotrophy to heterotrophy. With little glacial melt disturbance (during cold El Niño spring 2015), clear waters enabled high benthic microalgal production, resulting in net autotrophic benthic communities. In contrast, water column turbidity caused by increased glacial melt run-off (summer 2015 and warm La Niña spring 2016) limited benthic microalgal production and turned the benthic communities net heterotrophic. Ongoing accelerations in glacial melt and run-off may steer shallow Antarctic seafloor ecosystems towards net heterotrophy, altering the metabolic balance of benthic communities and potentially impacting the carbon balance and food webs at the Antarctic seafloor.Fil: Braeckman, Ulrike. University of Ghent; BélgicaFil: Pasotti, Francesca. University of Ghent; BélgicaFil: Hoffmann, Ralf. Helmholtz Zentrum für Polar-und Meeresforschung; AlemaniaFil: Vázquez, Susana Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Wulff, Angela. University Goteborg; SueciaFil: Schloss, Irene Ruth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Falk, Ulrike. Universitat Bremen; AlemaniaFil: Deregibus, Dolores. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lefaible, Nene. University of Ghent; BélgicaFil: Torstensson, Anders. University Goteborg; SueciaFil: Al Handal, Adil. University Goteborg; SueciaFil: Wenzhöfer, Frank. Max Planck Institute for Marine Microbiology; AlemaniaFil: Vanreusel, Ann. University of Ghent; Bélgic

Photosynthetic light requirement near the theoretical minimum detected in Arctic microalgae

Photosynthesis is one of the most important biological processes on Earth, providing the main source of bioavailable energy, carbon, and oxygen via the use of sunlight. Despite this importance, the minimum light level sustaining photosynthesis and net growth of primary producers in the global ocean is still unknown. Here, we present measurements from the MOSAiC field campaign in the central Arctic Ocean that reveal the resumption of photosynthetic growth and algal biomass buildup under the ice pack at a daily average irradiance of not more than 0.04 ± 0.02 µmol photons m−2 s−1 in late March. This is at least one order of magnitude lower than previous estimates (0.3–5 µmol photons m−2 s−1) and near the theoretical minimum light requirement of photosynthesis (0.01 µmol photons m−2 s−1). Our findings are based on measurements of the temporal development of the under-ice light field and concurrent measurements of both chlorophyll a concentrations and potential net primary production underneath the sea ice at 86 °N. Such low light requirements suggest that euphotic zones where photosynthesis can occur in the world’s oceans may extend further in depth and time, with major implications for global productivity estimates

Prevalence of BRCA1 and BRCA2 pathogenic variants in a large, unselected breast cancer cohort.

Breast cancer patients with BRCA1/2-driven tumors may benefit from targeted therapy. It is not clear whether current BRCA screening guidelines are effective at identifying these patients. The purpose of our study was to evaluate the prevalence of inherited BRCA1/2 pathogenic variants in a large, clinically representative breast cancer cohort and to estimate the proportion of BRCA1/2 carriers not detected by selectively screening individuals with the highest probability of being carriers according to current clinical guidelines. The study included 5,122 unselected Swedish breast cancer patients diagnosed from 2001 to 2008. Target sequence enrichment (48.48 Fluidigm Access Arrays) and sequencing were performed (Illumina Hi-Seq 2,500 instrument, v4 chemistry). Differences in patient and tumor characteristics of BRCA1/2 carriers who were already identified as part of clinical BRCA1/2 testing routines and additional BRCA1/2 carriers found by sequencing the entire study population were compared using logistic regression models. Ninety-two of 5,099 patients with valid variant calls were identified as BRCA1/2 carriers by screening all study participants (1.8%). Only 416 study participants (8.2%) were screened as part of clinical practice, but this identified 35 out of 92 carriers (38.0%). Clinically identified carriers were younger, less likely postmenopausal and more likely to be associated with familiar ovarian cancer compared to the additional carriers identified by screening all patients. More BRCA2 (34/42, 81.0%) than BRCA1 carriers (23/50, 46%) were missed by clinical screening. In conclusion, BRCA1/2 mutation prevalence in unselected breast cancer patients was 1.8%. Six in ten BRCA carriers were not detected by selective clinical screening of individuals

Pathways to child and adolescent psychiatric clinics: a multilevel study of the significance of ethnicity and neighbourhood social characteristics on source of referral

<p>Abstract</p> <p>Background</p> <p>In the Swedish society, as in many other societies, many children and adolescents with mental health problems do not receive the help they need. As the Swedish society becomes increasingly multicultural, and as ethnic and economic residential segregation become more pronounced, this study utilises ethnicity and neighbourhood context to examine referral pathways to child and adolescent psychiatric (CAP) clinics.</p> <p>Methods</p> <p>The analysis examines four different sources of referrals: family referrals, social/legal agency referrals, school referrals and health/mental health referrals. The referrals of 2054 children aged 11-19 from the Stockholm Child-Psychiatric Database were studied using multilevel logistic regression analyses.</p> <p>Results</p> <p>Results indicate that ethnicity played an important role in how children and adolescents were referred to CAP-clinics. Family referrals were more common among children and adolescents with a Swedish background than among those with an immigrant background. Referrals by social/legal agencies were more common among children and adolescents with African and Asian backgrounds. Children with Asian or South American backgrounds were more likely to have been referred by schools or by the health/mental health care sector. A significant neighbourhood effect was found in relation to family referrals. Children and adolescents from neighbourhoods with low levels of socioeconomic deprivation were more likely to be referred to CAP-clinics by their families in comparison to children from other neighbourhoods. Such differences were not found in relation in relation to the other sources of referral.</p> <p>Conclusions</p> <p>This article reports findings that can be an important first step toward increasing knowledge on reasons behind differential referral rates and uptake of psychiatric care in an ethnically diverse Swedish sample. These findings have implications for the design and evaluation of community mental health outreach programs and should be considered when developing measures and strategies intended to reach and help children with mental health problems. This might involve providing information about the availability and accessibility of health care for children and adolescents with mental health problems to families in certain neighbourhoods and with different ethnic backgrounds.</p

Multiomics in the central Arctic Ocean for benchmarking biodiversity change

Multiomics approaches need to be applied in the central Arctic Ocean to benchmark biodiversity change and to identify novel species and their genes. As part of MOSAiC, EcoOmics will therefore be essential for conservation and sustainable bioprospecting in one of the least explored ecosystems on Earth

Ecophysiology of Polar Sea Ice Microorganisms in a Changing World

Earth’s oceans are predominantly cold, with nearly 90% of their volume having temperatures below 5 °C. Microorganisms commonly referred to as psychrophiles have adapted to the temperatures of these cold waters. The most extreme psychrophiles are found inside the sea ice of polar oceans, where bacterial growth can be observed down to -20 °C. Sea ice consists of a matrix of ice and high-saline water (brine) that provide a unique habitat for microbial communities. Microscopic algae and bacteria dominate these extreme environments, which are considered very stressful as they are characterised by large variations in salinity, low temperatures, and low radiation levels. However, the brine-filled channels also provide a platform from which microscopic algae remain in the euphotic zone and refugees from significant grazing, thereby enabling net autotrophic growth. As a result, sea ice hosts some of the highest chlorophyll a concentrations on the planet, and is one of the most important factors controlling primary production and bloom dynamics in polar areas. In this thesis, I focus on the ecophysiology of psychrophiles adapted to the sea ice environment. Physiological acclimation to environmental change needs to be studied in order to address how different stressors may influence organisms’ capacity to tolerate both naturally- and climatically-driven changes. Extremophiles growing close to their physiological limits may be especially susceptible to environmental stressors, such as rapid climate change. Therefore, a series of studies has been performed to investigate how environmental stressors, such as increased temperature and elevated CO2, affect microbial physiology and community structure in polar areas. The ecophysiology of sea ice microorganisms has been addressed in laboratory experiments (Papers I, II, and IV) and in field measurements (Paper III). In brief, relatively small changes in temperature had considerable effects on the physiology of sea ice diatoms, and indirectly affected the structure of sea ice bacterial communities. Increasing temperature (on both climatic and seasonal scales) positively affected the growth and primary productivity of two sea ice diatom species, and negatively affected the taxonomic richness and diversity of sea ice bacterial communities, probably by the subsequent changes in salinity. On the other hand, sea ice diatoms seem quite tolerant to changes in pH and partial pressure of CO2 (pCO2) in terms of growth, probably due to the fact that they grow in an environment with large seasonal variations in the carbonate system. However, increased pCO2 resulted in other cellular changes that may have important ecological consequences, such as cellular stoichiometry. This includes changes in fatty acid composition and dissolved organic carbon exudation, which are important components in food webs and biogeochemistry in many marine ecosystems. Although most studies on marine organisms have focused on short-term responses to increased pCO2, acclimation and adaptation are key components in order to identify the consequences of climate change in biological systems. In Paper IV, the physiological responses to long-term acclimation to high pCO2 were investigated in the psychrophilic sea ice diatom Nitzschia lecointei. After long-term acclimation (194 days), a small reduction in growth was detected at high pCO2. Previous short-term experiments have failed to detect altered growth in N. lecointei at high pCO2, which illustrates the importance of experimental duration in ocean acidification studies