Methane seepage along the Hikurangi Margin of New Zealand : geochemical and physical data from the water column, sea surface and atmosphere

The concentration and carbon isotope values of dissolved methane were measured in the water column at Rock Garden, Omakere Ridge and Wairarapa areas in the first dedicated cold seep investigation along the Hikurangi Margin of New Zealand. These measurements provide a high resolution impression of the methane distribution in the water column and show that these seep sites are actively venting methane with varying intensity. The highest concentrations (up to 3500 nM) measured in water samples obtained from Conductivity–Temperature–Depth (CTD) operations were at Faure Site of Rock Garden. Here, seafloor bubble release was observed by ROV. The Omakere Ridge area is actively venting over almost its entire length (not, vert, similar 25 km), in particular at Bear's Paw, a newly discovered seep site. In the Wairarapa area another new seep site called Tui was discovered, where methane measurements often exceeded 500 nM. No evidence was obtained from water column or sea surface measurements along the Hikurangi Margin to indicate that methane from seeps is reaching the sea surface. In fact, a consistent upper boundary was observed at a density of 26.85 kg/m3, which occurs at about 500 m below sea surface, above which methane decreased to background concentrations. No obvious oceanographic feature is associated with this 500 m CH4 boundary. Bubble dissolution calculations show that about 500 m was also the model-derived maximum bubble rise height. A wide range of δ13CCH4 values from − 71 to − 19‰ (VPDB) were measured, with the highest CH4 concentrations having the lowest δ13CCH4 values of about − 71 to − 68‰. Simple mixing and isotope fractionation calculations show that changes of δ13CCH4 values are predominantly caused by the dilution of seep fluids with the seawater, with some anaerobic oxidation also occurring

Puzzling subunits of mitochondrial cytochrome reductase

The ubiquinol-cytochrome c reductase complex, like the other proton-pumping respiratory complexes of mitochondria, is an assembly of many different subunits. However, only a few of these subunits participate directly in the electron transfer and proton translocation. The roles of the other subunits are largely unknown. We discuss here some intriguing features of two of these subunits

Microbiological pathogen analysis in native versus periprosthetic joint infections: a retrospective study

Background The presence or absence of an implant has a major impact on the type of joint infection therapy. Thus, the aim of this study was the examination of potential differences in the spectrum of pathogens in patients with periprosthetic joint infections (PJI) as compared to patients with native joint infections (NJI). Methods In this retrospective study, we evaluated culture-positive synovial fluid samples of 192 consecutive patients obtained from January 2018 to January 2020 in a tertiary care university hospital. For metrically distributed parameters, Mann–Whitney U was used for comparison between groups. In case of nominal data, crosstabs and Chi-squared tests were implemented. Results Overall, 132 patients suffered from periprosthetic joint infections and 60 patients had infections of native joints. The most commonly isolated bacteria were coagulase-negative Staphylococci (CNS, 28%), followed by Staphylococcus aureus (S. aureus, 26.7%), and other bacteria, such as Streptococci (26.3%). We observed a significant dependence between the types of bacteria and the presence of a joint replacement (p < 0.05). Accordingly, detections of CNS occurred 2.5-fold more frequently in prosthetic as compared to native joint infections (33.9% vs. 13.4% p < 0.05). In contrast, S. aureus was observed 3.2-fold more often in NJIs as compared to PJIs (52.2% vs. 16.4%, p < 0.05). Conclusion The pathogen spectra of periprosthetic and native joint infections differ considerably. However, CNS and S. aureus are the predominant microorganisms in both, PJIs and NJIs, which may guide antimicrobial therapy until microbiologic specification of the causative pathogen