Cyanobacteria net community production in the Baltic Sea as inferred from profiling pCO(2) measurements

Organic matter production by cyanobacteria blooms is a major environmental concern for the Baltic Sea, as it promotes the spread of anoxic zones. Partial pressure of carbon dioxide (pCO(2)) measurements carried out on Ships of Opportunity (SOOP) since 2003 have proven to be a powerful tool to resolve the carbon dynamics of the blooms in space and time. However, SOOP measurements lack the possibility to directly constrain depth-integrated net community production (NCP) in moles of carbon per surface area due to their restriction to the sea surface. This study tackles the knowledge gap through (1) providing an NCP best guess for an individual cyanobacteria bloom based on repeated profiling measurements of pCO(2) and (2) establishing an algorithm to accurately reconstruct depth-integrated NCP from surface pCO(2) observations in combination with modelled temperature profiles.Goal (1) was achieved by deploying state-of-the-art sensor technology from a small-scale sailing vessel. The low-cost and flexible platform enabled observations covering an entire bloom event that occurred in July-August 2018 in the Eastern Gotland Sea. For the biogeochemical interpretation, recorded pCO(2) profiles were converted to C-T*, which is the dissolved inorganic carbon concentration normalised to alkalinity. We found that the investigated bloom event was dominated by Nodularia and had many biogeochemical characteristics in common with blooms in previous years. In particular, it lasted for about 3 weeks, caused a C-T* drawdown of 90 mu mol kg(-1), and was accompanied by a sea surface temperature increase of 10 degrees C. The novel finding of this study is the vertical extension of the C-T* drawdown up to the compensation depth located at around 12 m. Integration of the C-T* drawdown across this depth and correction for vertical fluxes leads to an NCP best guess of similar to 1:2 mol m(-2) over the productive period.Addressing goal (2), we combined modelled hydrographical profiles with surface pCO(2) observations recorded by SOOP Finnmaid within the study area. Introducing the temperature penetration depth (TPD) as a new parameter to integrate SOOP observations across depth, we achieve an NCP reconstruction that agrees to the best guess within 10 %, which is considerably better than the reconstruction based on a classical mixed-layer depth constraint.Applying the TPD approach to almost 2 decades of surface pCO(2) observations available for the Baltic Sea bears the potential to provide new insights into the control and long-term trends of cyanobacteria NCP. This understanding is key for an effective design and monitoring of conservation measures aiming at a Good Environmental Status of the Baltic Sea

Individuality and temporal stability of the human gut microbiome

Introduction: The breakthrough of next generation sequencing-technologies has enabled large-scale studies of natural microbial communities and the 16S rRNA genes have been widely used as a phylogenetic marker to study community structure. However, major limitations of this approach are that neither strain-level resolution nor genomic context of microorganisms can be provided. This information, however, is crucial to answer fundamental questions about the temporal stability and distinctiveness of natural microbial communities.Material and methods: We developed a methodological framework for metagenomic single nucleotide polymorphism (SNP) variation analysis and applied it to publicly available data from 252 human fecal samples from 207 European and North American individuals. We further analyzed samples from 43 healthy subjects that were sampled at least twice over time intervals of up to one year and measured population similarities of dominant gut species.Results: We detected 10.3 million SNPs in 101 species, which nearly amounts to the number identified in more than 1,000 humans.Conclusion: The most striking result was that host-specific strains appear to be retained over long time periods. This indicates that individual-specific strains are not easily exchanged with the environment and furthermore, that an individuals appear to have a unique metagenomic genotype. This, in turn, is linked to implications for human gut physiology, such as the stability of antibiotic resistance potential

Genomic variation landscape of the human gut microbiome

While large-scale efforts have rapidly advanced the understanding and practical impact of human genomic variation, the latter is largely unexplored in the human microbiome. We therefore developed a framework for metagenomic variation analysis and applied it to 252 fecal metagenomes of 207 individuals from Europe and North America. Using 7.4 billion reads aligned to 101 reference species, we detected 10.3 million single nucleotide polymorphisms (SNPs), 107,991 short indels, and 1,051 structural variants. The average ratio of non-synonymous to synonymous polymorphism rates of 0.11 was more variable between gut microbial species than across human hosts. Subjects sampled at varying time intervals exhibited individuality and temporal stability of SNP variation patterns, despite considerable composition changes of their gut microbiota. This implies that individual-specific strains are not easily replaced and that an individual might have a unique metagenomic genotype, which may be exploitable for personalized diet or drug intake

Continuing education Ultrasound-guided injections in the middle and lower cervical spine

Abstract Injection therapies play a major role in the treatment of cervical pain and are becoming integral parts of a multidisciplinary approach in treatment and rehabilitation of such patients. Pararadicular-and facet-joint injections in the cervical spine are preferentially performed under computed tomography (CT) or fluoroscopy-guidance. In this article we present an alternative, simple and easy to learn step by step US-guided technique for injection therapy in the cervical spine