Survival of Reed Warbler Acrocephalus scirpaceus clutches in relation to nest position

Nest survival was studied in relation to nest position of 164 nests of the Reed Warbler Acrocephalus scirpaceus in the Southeastern part of the Czech Republic in 1993. Breeding was successful in 91 (55.5%) cases, whereas 40 (24.4%) were predated, 19 (11.6%) were parasitized by the Cuckoo Cuculus canorus and 14 (8.5%) were destroyed by other causes. Of the predated nests, small mammals accounted for 26 (65.0%) and unknown predators for 14 (35.0%) nests. Rates of predation and parasitism varied in relation to a series of habitat factors and Reed Warblers avoided nest sites most vulnerable to predation or parasitism. Concealed places in the vegetation far away from trees were the safest nest sites.     

Flesh‐eating Streptococcus pyogenes triggers the expression of receptor activator of nuclear factor‐κB ligand

Human CD46 is a receptor for the M protein of group A streptococcus (GAS). The emm1 GAS strain GAS472 was isolated from a patient suffering from streptococcal toxic shock‐like syndrome. Human CD46‐expressing transgenic (Tg) mice developed necrotizing fasciitis associated with osteoclast‐mediated progressive and severe bone destruction in the hind paws 3 days after subcutaneous infection with 5 × 10⁵ colony‐forming units of GAS472. GAS472 infection induced expression of the receptor activator of nuclear factor‐κB ligand (RANKL) while concomitantly reducing osteoprotegerin expression in the hind limb bones of CD46 Tg mice. Micro‐computed tomography analysis of the bones suggested that GAS472 infection induced local bone erosion and systemic bone loss in CD46 Tg mice. Because treatment with monoclonal antibodies (mAbs) against mouse CD4⁺ and CD8⁺ T lymphocytes did not inhibit osteoclastogenesis, T lymphocyte‐derived RANKL was not considered a major contributor to massive bone loss during GAS472 infection. However, immunohistochemical analysis of the hind limb bones showed that GAS472 infection stimulated RANKL production in various bone marrow cells, including fibroblast‐like cells. Treatment with a mAb against mouse RANKL significantly inhibited osteoclast formation and bone resorption. These data suggest that increased expression of RANKL in heterogeneous bone marrow cells provoked bone destruction during GAS infection.     

The NAD-Booster Nicotinamide Riboside Potently Stimulates Hematopoiesis through Increased Mitochondrial Clearance

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Homeostatic Intrinsic Plasticity Is Functionally Altered in Fmr1 KO Cortical Neurons

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Host genetic requirements for DNA release of lactococcal phage TP901-1

The first step in phage infection is the recognition of, and adsorption to, a receptor located on the host cell surface. This reversible host adsorption step is commonly followed by an irreversible event, which involves phage DNA delivery or release into the bacterial cytoplasm. The molecular components that trigger this latter event are unknown for most phages of Gram-positive bacteria. In the current study, we present a comparative genome analysis of three mutants of Lactococcus cremoris 3107, which are resistant to the P335 group phage TP901-1 due to mutations that affect TP901-1 DNA release. Through genetic complementation and phage infection assays, a predicted lactococcal three-component glycosylation system (TGS) was shown to be required for TP901-1 infection. Major cell wall saccharidic components were analysed, but no differences were found. However, heterologous gene expression experiments indicate that this TGS is involved in the glucosylation of a cell envelope-associated component that triggers TP901-1 DNA release. To date, a saccharide modification has not been implicated in the DNA delivery process of a Gram-positive infecting phage.     

Metabolic reconstruction and modeling of nitrogen fixation in Rhizobium etli

Rhizobiaceas are bacteria that fix nitrogen during symbiosis with plants. This symbiotic relationship is crucial for the nitrogen cycle, and understanding symbiotic mechanisms is a scientific challenge with direct applications in agronomy and plant development. Rhizobium etli is a bacteria which provides legumes with ammonia (among other chemical compounds), thereby stimulating plant growth. A genome-scale approach, integrating the biochemical information available for R. etli, constitutes an important step toward understanding the symbiotic relationship and its possible improvement. In this work we present a genome-scale metabolic reconstruction (iOR363) for R. etli CFN42, which includes 387 metabolic and transport reactions across 26 metabolic pathways. This model was used to analyze the physiological capabilities of R. etli during stages of nitrogen fixation. To study the physiological capacities in silico, an objective function was formulated to simulate symbiotic nitrogen fixation. Flux balance analysis (FBA) was performed, and the predicted active metabolic pathways agreed qualitatively with experimental observations. In addition, predictions for the effects of gene deletions during nitrogen fixation in Rhizobia in silico also agreed with reported experimental data. Overall, we present some evidence supporting that FBA of the reconstructed metabolic network for R. etli provides results that are in agreement with physiological observations. Thus, as for other organisms, the reconstructed genome-scale metabolic network provides an important framework which allows us to compare model predictions with experimental measurements and eventually generate hypotheses on ways to improve nitrogen fixation.     

A century of conservation: The ongoing recovery of Svalbard reindeer

Several caribou and reindeer (Rangifer tarandus) populations have experienced recent population declines, often attributed to anthropogenic stressors such as harvesting, landscape fragmentation, and climate change. Svalbard reindeer (R. t. platyrhynchus), the wild reindeer subspecies endemic to the high-Arctic Svalbard archipelago, was protected in 1925, after most subpopulations had been eradicated by harvest. Although direct pressure from harvest has ceased, indirect anthropogenic stressors from environmental changes have increased in this climate change hot spot. An assessment of the current distribution and abundance is therefore urgently needed. We combined distance sampling (300 km transects, n = 489 reindeer groups) and total counts (1,350 km², n = 1,349 groups) to estimate the Svalbard reindeer distribution and abundance across its entire range, which we compared with historical data from the literature and radiocarbon-dated bones. Reindeer have now recolonized nearly all non-glaciated land (i.e., areas occupied prior to human presence), and their spatial variation in abundance reflects vegetation productivity. Independent of vegetation productivity, however, recently recolonized areas have lower reindeer densities than areas not subject to past extirpation. This suggests that recovery from past overharvesting is still in progress. These incompletely recovered areas are potential targets for increased monitoring frequency and maintaining strict conservation to follow the Svalbard management goal (i.e., virtually untouched wilderness areas). Because of such ongoing recolonization, possibly combined with vegetation greening effects of recent warming, our status estimate of Svalbard reindeer abundance (22,435 [95% CI = 21,452–23,425]) is more than twice a previous estimate based on opportunistic counts. Thus, although our study demonstrates the successful outcome of strict harvesting control implemented a century ago, current and future population trajectories are likely shaped by climate change. © 2019 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Prognostic molecular markers in pediatric liver disease – Are there any?

Pediatric liver disease (PLD) is a major cause of severe morbidity and prolonged hospitalizations in children. Stratifying patients in terms of prognosis remains challenging. The limited knowledge about molecular mechanisms causing and accompanying PLD remains the main obstacle in a search for reliable prognostic biomarkers. A systematic search of MEDLINE via PubMed and Embase via OVID was conducted on studies published between August 2007 and August 2017. Molecular markers with a prognostic potential in terms of survival, need for liver transplantation or disease progression/regression were selected. In general, identified studies were single center smaller case-control studies or case series with a low level of evidence and a high risk of bias. Only 23 studies comprising 898 patients could be included, mostly focusing on biliary atresia, non-alcoholic fatty liver disease, viral hepatitis, and LT; and markers related to morphogenesis and fibrosis. Furthermore, molecular markers in metabolic pathways and inflammation shown to be relevant, however requiring further validation. Hence, further biological and clinical studies are needed to gain greater molecular insight into PLD.