Carbon dioxide fluxes increase from day to night across European streams

Globally, inland waters emit over 2 Pg of carbon per year as carbon dioxide, of which the majority originates from streams and rivers. Despite the global significance of fluvial carbon dioxide emissions, little is known about their diel dynamics. Here we present a large-scale assessment of day- and night-time carbon dioxide fluxes at the water-air interface across 34 European streams. We directly measured fluxes four times between October 2016 and July 2017 using drifting chambers. Median fluxes are 1.4 and 2.1 mmol m−2 h−1 at midday and midnight, respectively, with night fluxes exceeding those during the day by 39%. We attribute diel carbon dioxide flux variability mainly to changes in the water partial pressure of carbon dioxide. However, no consistent drivers could be identified across sites. Our findings highlight widespread day-night changes in fluvial carbon dioxide fluxes and suggest that the time of day greatly influences measured carbon dioxide fluxes across European streams

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Disparate progenitor cell populations contribute to maintenance and repair neurogenesis in the zebrafish olfactory epithelium

Olfactory sensory neurons (OSNs) undergo constant turnover under physiological conditions but also regenerate efficiently following tissue injury. Maintenance and repair neurogenesis in the olfactory epithelium (OE) have been attributed to the selective activity of globose (GBCs) and horizontal basal cells (HBCs), respectively. In zebrafish, cells with GBC-like properties are localized to the peripheral margins of the sensory OE and contribute to OSN neurogenesis in the intact OE, while cells that resemble HBCs at the morphological and molecular level are more uniformly distributed. However, the contribution of these cells to the restoration of the injured OE has not been demonstrated. Here, we provide a detailed cellular and molecular analysis of the tissue response to injury and show that a dual progenitor cell system also exists in zebrafish. Zebrafish HBCs respond to the structural damage of the OE and generate a transient population of proliferative neurogenic progenitors that restores OSNs. In contrast, selective ablation of OSNs by axotomy triggers neurogenic GBC proliferation, suggesting that distinct signaling events activate GBC and HBC responses. Molecular analysis of differentially expressed genes in lesioned and regenerating OEs points toward an involvement of the canonical Wnt/β-catenin pathway. Activation of Wnt signaling appears to be sufficient to stimulate mitotic activity, while inhibition significantly reduces, but does not fully eliminate, HBC responses. Zebrafish HBCs are surprisingly active even under physiological conditions with a strong bias toward the zones of constitutive OSN neurogenesis, suggestive of a direct lineage relationship between progenitor cell subtypes.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Calcium and vitamin D metabolism in granulomatous diseases.

Overproduction of the active metabolite of vitamin D 1,25-dihydroxyvitamin D (1,25(OH)2D) has been described in sarcoidosis and other granulomatous diseases. High circulating concentrations of 1,25(OH)2D lead to increased intestinal absorption of calcium, possibly to enhanced bone resorption, and may result in hypercalcaemia and/or hypercalciuria. Data obtained in vivo and in vitro demonstrated that the unregulated production of 1,25(OH)2D lies within the granulomatous tissue and is controlled by glucocorticoids. This abnormal production of 1,25(OH)2D seems to be a general phenomenon of granulomatous processes, which is not exceptional in sarcoidosis, but appears seldom in tuberculosis. These abnormalities, however, are not pathognomonic of granulomatous processes, since they have been described in other diseases such as lymphomas.Journal ArticleResearch Support, Non-U.S. Gov'tReviewSCOPUS: re.jinfo:eu-repo/semantics/publishe