Bacteria-induced morphogenesis of Ulva intestinalis and Ulva mutabilis (Chlorophyta): a contribution to the lottery theory

Abstract

The green marine macroalgae of the class Ulvophyceae (Ulvophytes) are common algae distributed worldwide particularly in intertidal areas, which play a key role in aquatic ecosystems. They are potentially valuable resources for food, animal feed and fuel but can also cause massive nuisance blooms. Members of Ulvaceae, like many other seaweeds, harbour a rich diversity of epiphytic bacteria with functions related to host growth and morphological development. In the absence of appropriate bacterially derived signals, germ cells of the genus Ulva develop into 'atypical' colonies consisting of undifferentiated cells with abnormal cell walls. This paper examines the specificity of bacteria-induced morphogenesis in Ulva, by cross-testing bacteria isolated from several Ulva species on two Ulva species, the emerging model system Ulva mutabilis and the prominent biofouler species Ulva intestinalis. We show that pairs of bacterial strains isolated from species other than U. mutabilis and U. intestinalis can fully rescue axenic plantlets generated either from U. mutabilis or U. intestinalis gametes. This laboratory-based study demonstrates that different compositions of microbial communities with similar functional characteristics can enable complete algal morphogenesis and thus supports the 'competitive lottery' theory for how symbiotic bacteria drive algal development.

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Seasonal and spatial variations of prokaryoplankton communities in a salinity-influenced watershed, China

Abstract

Prokaryotes represent the largest biodiversity pool and drive the biogeochemical cycles in fluvial environments. However, the mechanisms underlying the assembly of prokaryotic communities are largely unexplored at taxonomic and functional levels, simultaneously. Here, we investigated the spatio-seasonal distribution of prokaryoplankton communities in a salinity-influenced watershed, China using 16S rRNA gene amplicon sequencing. The OTUs were divided into core and satellite, based on a statistical approach. Our results indicated that the core taxa accounted for 87.4% of all the communities, predominantly including Betaproteobacteria, Actinobacteria and Thaumarchaeota. Whereas 10 of 22 metabolic phenotypes annotated using METAGENassist had significantly higher relative abundances in the core than satellite communities. Temporal variations in the composition of ammonia-oxidizing prokaryotes could be attributed to the seasonal nutrient concentrations. Multivariate statistical analysis indicated that environmental filtering rather than dispersal limitation is the primary mechanism driving the assembly of the whole, core and satellite communities at both taxonomic and functional levels. Network analysis revealed that the mutualistic interactions might also have certain roles in the assembly of the core taxonomic community. However, taxonomic community fluctuations can only partially reflect the functional community variations. Collectively, this study significantly advanced our understanding of the biogeographic pattern of the fluvial prokaryotic communities.

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Effect of dietary nucleosides and yeast extracts on composition and metabolic activity of infant gut microbiota in PolyFermS colonic fermentation models

Abstract

Nucleotides (NT) and nucleosides (NS) are added to infant formula to mimic the content of breast milk, but little is known about their impact on infant gut microbiota. In this study, we tested the effect of NS and of yeast extracts (YE) with different NT content using PolyFermS continuous fermentation models mimicking formula-fed, healthy and enteropathogen-contaminated infant gut microbiota. Microbiota composition, short-chain fatty acid (SCFA) formation and gene expression were determined. NS, and to a larger extend YE modulated microbiota composition and increased metabolic activity in both models. Anaerococcus, Peptoniphilus, Fusobacterium, Lactobacillus/Pediococcus/Leuconostoc and Veillonella were enhanced when YE and/or NS were added. The production of SCFA increased with the level of supplied NT equivalents. Addition of NS and YE reduced colonization of Salmonella compared to control periods. Gene expression analysis confirmed taxonomical changes and indicated functional responses to YE. Transcripts related to NT and sulfur metabolism and iron acquisition increased while biosynthesis of co-factors and vitamins decreased after YE addition. Elevated butyrate formation correlated with increased transcripts encoding key enzymes of the two major butyrate synthesis pathways. Our results uncover a strong dose-dependent modulation of NS and YE on infant gut microbiota composition and metabolic activity.

http://ift.tt/2utEdUE

High-throughput sequencing of microbial eukaryotes in Lake Baikal reveals ecologically differentiated communities and novel evolutionary radiations

Abstract

We performed high-throughput 18S rDNA V9 region sequencing analyses of microeukaryote (protist) communities at seven sites with depths ranging from 0 to 1450 m in the southern part of Lake Baikal. We show that microeukaryotic diversity differed according to water column depth and sediment depth. Chrysophytes and perkinsids were diverse in subsurface samples, novel radiations of petalomonads and Ichthyobodo relatives were found in benthic samples, and a broad range of divergent OTUs were detected in deep subbenthic samples. Members of clades usually associated with marine habitats were also detected, including syndineans for the first time in freshwater systems. Fungal- and cercozoan-specific c. 1200 bp amplicon clone libraries also revealed many novel lineages in both planktonic and sediment samples at all depths, a novel radiation of aphelids in shallower benthic samples, and partitioning of sarcomonad lineages in shallow vs deep benthic samples. Putative parasitic lineages accounted for 12.4% of overall reads, including a novel radiation of Ichthyobodo (fish parasite) relatives. Micrometazoans were also analysed, including crustaceans, rotifers and nematodes. The deepest (>1000 m) subsurface sediment samples harboured some highly divergent sequence types, including heterotrophic flagellates, parasites, putative metazoans and sequences likely representing organisms originating from higher up in the water column.

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Rapamycin prolongs graft survival and induces CD4+IFN-[gamma]+IL-10+ regulatory type 1 cells in old recipient mice.

Background: Although the elderly represents a rapidly growing population among transplant recipients, age-specific aspects have not been considered sufficiently in clinical trials. Moreover, age-specific effects of immunosuppressive therapies remain poorly understood. Methods: Here, we assessed the impact of Rapamycin on alloimmune responses in old recipients using a fully MHC-mismatched murine transplantation model. Results: Old untreated recipients displayed a prolonged skin graft survival compared to their young counterparts, an observation that confirmed data of our previous experiments. Rapamycin led to a significant prolongation of graft survival in both, young and old recipients. However, graft survival was age-dependent and extended in old vs. young recipients (19 days vs. 12 days, p=0.004). This age-specific effect was not linked to changes in frequencies or subset composition of either CD8+ or CD4+ T cells. Moreover, antiproliferative effects of Rapamycin on CD8+ and CD4+ T cells as assessed by in vivo BrdU-incorporation were comparable and age-independent. In contrast, the systemic production of IL-10 was markedly elevated in old recipients treated with Rapamycin. In parallel to this shift in cytokine balance, IFN-[gamma]/IL-10 double-positive regulatory type 1 cells emerged during Th1-differentiation of old T helper cells in presence of Rapamycin. Similarly, CD4+IFN-[gamma]+IL-10+ cells expanded among Foxp3-negative cells after in vivo treatment of old recipients with Rapamycin. Conclusions: Our results highlight novel aspects of age-dependent immunosuppressive effects of Rapamycin, with relevance for age-specific immunosuppressive regimens. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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A surveillance study to determine the accuracy of mild traumatic brain injury diagnosis in an emergency department: protocol for a retrospective cohort study

Introduction

Previous literature confirms that a mild traumatic brain injury (mTBI) may result in long-term emotional impacts and, in vulnerable subgroups, cognitive deficits. The accurate diagnosis of mTBI and its written documentation is an important first step towards providing appropriate and timely clinical care. Surveillance studies involving emergency department (ED) and hospital-based data need to be prioritised as these provide incident mTBI estimates. This project will advance existing research findings by estimating the occurrence of mTBI among those attending an ED and quantifying the accuracy of mTBI diagnoses recorded by ED staff through a comprehensive audit of ED records.

Methods and analysis

Retrospective chart reviews (between June 2015 and June 2016) of electronic clinical records from an ED in Sydney (New South Wales, Australia) will be conducted. The study population will include persons aged 18–65 years who attended the ED with any clinical features potentially indicative of mTBI. The WHO operational criteria for the clinical identification of mTBI cases is the presence of: (1) a Glasgow Coma Scale (GCS) of 13–15 after 30 min postinjury or on presentation to hospital; (2) one or more of the following: post-traumatic amnesia (PTA) of less than 24 hours' duration, confusion or disorientation, a witnessed loss of consciousness for ≤30 min and/or a positive CT brain scan. We estimate that 30 000 ED attendances will be screened and that a sample size of 500 cases with mTBI will be identified during this 1-year period, which will provide reliable estimates of mTBI occurrence in the ED setting.

Ethics and dissemination

The study was approved by the Northern Sydney Local Health District Ethics Committee. The committee deemed this study as low risk in terms of ethical issues. The written papers from this study will be submitted for publication in quality peer-reviewed medical and health journals. Study findings will be disseminated via presentations at national/international conferences and peer-reviewed journals.

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Optimal dose of succinylcholine for laryngeal mask airway insertion: systematic review, meta-analysis and metaregression of randomised control trials

Objectives

To evaluate the optimal dose of succinylcholine for laryngeal mask airway (LMA) insertion and all related morbidities.

Design

Systematic review, meta-analysis and metaregression of randomised controlled trials (RCTs).

Data source and study eligibility criteria

A comprehensive search of RCTs in the PubMed, Embase, the Cochrane Library and the ClinicalTrials.gov registry up to July 2016 and articles that evaluated the use of succinylcholine chloride for LMA insertion were included in the analyses. The relative risk (RR) and the corresponding 95% CIs were determined.

Intervention

Succinylcholine as the coinduction agent and the doses were divided into mini (≤0.3 mg/kg) and low (0.3–1.0 mg/kg) doses for dose-dependent effect analyses.

Primary and secondary outcomes

The primary outcome was the first-attempt LMA insertion failure rate. Secondary outcomes included all related adverse events.

Results

Data from 10 RCTs comprising 625 participants showed that succinylcholine reduced the first-attempt LMA insertion failure rate (RR, 0.22; 95% CI 0.12 to 0.43), coughing and gagging (RR, 0.26; 95% CI 0.15 to 0.45) and laryngospasm (RR, 0.14; 95% CI 0.05 to 0.39). The use of succinylcholine did not result in a significant increase of postoperative myalgia (RR, 2.58; 95% CI 0.79 to 8.44) and did not reduce the risk of postoperative sore throat (RR, 0.76; 95% CI 0.55 to 1.03). Subgroup analysis further showed that low-dose succinylcholine reduced the LMA insertion failure rate and its related coughing and gagging when compared with mini dose.

Conclusion

The use of succinylcholine compared with none can facilitate LMA insertion and reduce insertion-related reflexes without significant postoperative myalgia. However, additional prospective studies with a larger sample size are required to fully evaluate the dose-dependent effect and complications of succinylcholine for LMA insertion.

http://ift.tt/2utiQCQ