ROS-driven cellular methane formation: Potential implications for health sciences

Abstract Recently it has been proposed that methane might be produced by all living organisms via a mechanism driven by reactive oxygen species that arise through the metabolic activity of cells. Here, we summarise details of this novel reaction pathway and discuss its potential significance for clinical and health sciences. In particular, we highlight the role of oxidative stress in cellular methane formation. As several recent studies also demonstrated the anti-inflammatory potential for exogenous methane-based approaches in mammalians, this article addresses the intriguing question if ROS-driven methane formation has a general physiological role and associated diagnostic potential

Stable Biological Production in the Eastern Equatorial Pacific Across the Plio-Pleistocene Transition (∼3.35–2.0 Ma)

Upwelling within the Eastern Equatorial Pacific (EEP) Ocean is a key factor for the Earth's climate because it supports >10% of the present-day biological production. The dynamics of upwelling in the EEP across the Plio-Pleistocene transition—an interval particularly relevant for understanding near-future warming due to Anthropocene-like atmospheric carbon-dioxide levels—have been intensively studied for the region east of the East Pacific Rise. In contrast, changes of the equatorial upwelling regime in the open Pacific Ocean west of this oceanographic barrier have received markedly less attention. We therefore provide new proxy records from Ocean Drilling Program Site 849 located within the EEP open-ocean upwelling regime. Our target interval (∼3.35–2.0 Ma) covers the Plio-Pleistocene transition characterized by the intensification of Northern Hemisphere Glaciation (iNHG). We use benthic δ18O values to generate a new, high-resolution age model for Site 849, and sand-accumulation rates together with benthic δ13C values to evaluate net export production. Although showing temporary substantial glacial-interglacial variations, our records indicate stability in net export production on secular timescales across the iNHG. We suggest the following processes to have controlled the long-term evolution of primary productivity at Site 849. First, nutrient export from the high latitudes to the EEP; second, a successive shoaling of the Pacific nutricline during the studied interval; and third, a simultaneous reduction in dust-borne iron input.publishedVersio

Umweltwissenschaften

Dieser einleitende Beitrag erläutert, was Umweltwissenschaften sind. Zunächst wird thematisiert, was ihr spezifischer Gegenstand ist: eine mehr oder weniger natürliche Umwelt von Menschen bzw. menschlichen Gesellschaften. Eine Untersuchung dieser Umwelt muss sowohl naturwissenschaftliche als auch geistes- und kulturwissenschaftliche Analysen umfassen, weil wir Menschen mit unserer natürlichen Umwelt nicht nur durch Kausalbeziehungen, sondern auch durch vielschichtige ästhetisch-symbolische Wahrnehmungen verbunden sind. Diese beiden Ebenen durchdringen sich im Bezug der Umweltwissenschaften auf so genannte Umweltprobleme. Verbunden sind die disziplinär und methodisch so unterschiedlichen Forschungsansätze, die zu den Umweltwissenschaften zählen und in diesem Band vorgestellt werden, durch eine gemeinsame Zielsetzung: Umweltprobleme zu beschreiben, zu erklären und zu prognostizieren bzw. deren Grundlagen zu erforschen, um einen rationalen, wissenschaftlich fundierten Umgang mit diesen Problemen zu ermöglichen. Innerhalb dieses Verbundes ergeben sich allerdings kommunikative Herausforderungen und auch Divergenzen, und zwar nicht nur aufgrund der je nach Wissenschaftsdisziplin unterschiedlichen Terminologie, Methodik und Gegenstandsauffassung (→Interdisziplinarität), sondern auch wegen konkurrierender Naturauffassungen und Idealvorstellungen über das Mensch/Gesellschaft-Natur-Verhältnis (→Natur-Kultur-Dualismus und Hybridisierung). In dieser Pluralität liegt die Stärke, aber auch die Herausforderung der Umweltwissenschaften

Stable Carbon Isotope Signature of Methane Released From Phytoplankton

Unidad de excelencia María de Maeztu CEX2019-000940-MAquatic ecosystems play an important role in global methane cycling and many field studies have reported methane supersaturation in the oxic surface mixed layer (SML) of the ocean and in the epilimnion of lakes. The origin of methane formed under oxic condition is hotly debated and several pathways have recently been offered to explain the "methane paradox." In this context, stable isotope measurements have been applied to constrain methane sources in supersaturated oxygenated waters. Here we present stable carbon isotope signatures for six widespread marine phytoplankton species, three haptophyte algae and three cyanobacteria, incubated under laboratory conditions. The observed isotopic patterns implicate that methane formed by phytoplankton might be clearly distinguished from methane produced by methanogenic archaea. Comparing results from phytoplankton experiments with isotopic data from field measurements, suggests that algal and cyanobacterial populations may contribute substantially to methane formationobserved in the SML of oceans and lakes

A fast and sensitive method for the continuous in situ determination of dissolved methane and its d13C-isotope ratio in surface waters

A fast and sensitive method for the continuous determination of methane (CH4) and its stable carbon isotopic values (d13C-CH4) in surface waters was developed by applying a vacuum to a gas/liquid exchange membrane and measuring the extracted gases by a portable cavity ring-down spectroscopy analyser (M-CRDS). The M-CRDS was calibrated and characterized for CH4 concentration and d13C-CH4 with synthetic water standards. The detection limit of the M-CRDS for the simultaneous determination of CH4 and d13CCH4 is 3.6 nmol L21 CH4. A measurement precision of CH4 concentrations and d13C-CH4 in the range of 1.1%, respectively, 1.7& (1r) and accuracy (1.3%, respectively, 0.8& [1r]) was achieved for single measurements and averaging times of 10 min. The response time s of 5765 s allow determination of d13C-CH4 values more than twice as fast than other methods. The demonstrated M-CRDS method was applied and tested for Lake Stechlin (Germany) and compared with the headspace-gas chromatography and fast membrane CH4 concentration methods. Maximum CH4 concentrations (577 nmol L21) and lightest d13C-CH4 (235.2&) were found around the thermocline in depth profile measurements. The M-CRDS-method was in good agreement with other methods. Temporal variations in CH4 concentration and d13C-CH4 obtained in 24 h measurements indicate either local methane production/oxidation or physical variations in the thermocline. Therefore, these results illustrate the need of fast and sensitive analyses to achieve a better understanding of different mechanisms and pathways of CH4 formation in aquatic environments

Hydrogen and carbon isotope fractionation during degradation of chloromethane by methylotrophic bacteria

Chloromethane (CH3Cl) is a widely studied volatile halocarbon involved in the destruction of ozone in the stratosphere. Nevertheless, its global budget still remains debated. Stable isotope analysis is a powerful tool to constrain fluxes of chloromethane between various environmental compartments which involve a multiplicity of sources and sinks, and both biotic and abiotic processes. In this study, we measured hydrogen and carbon isotope fractionation of the remaining untransformed chloromethane following its degradation by methylotrophic bacterial strains Methylobacterium extorquens CM4 and Hyphomicrobium sp. MC1, which belong to different genera but both use the cmu pathway, the only pathway for bacterial degradation of chloromethane characterized so far. Hydrogen isotope fractionation for degradation of chloromethane was determined for the first time, and yielded enrichment factors (epsilon) of -29 parts per thousand and -27 parts per thousand for strains CM4 and MC1, respectively. In agreement with previous studies, enrichment in C-13 of untransformed CH3Cl was also observed, and similar isotope enrichment factors (e) of -41 parts per thousand and -38 parts per thousand were obtained for degradation of chloromethane by strains CM4 and MC1, respectively. These combined hydrogen and carbon isotopic data for bacterial degradation of chloromethane will contribute to refine models of the global atmospheric budget of chloromethane

Enhancement of biomimetic enzymatic mineralization of gellan gum polysaccharide hydrogels by plant-derived gallotannins

Mineralization of hydrogel biomaterials with calcium phosphate (CaP) is considered advantageous for bone regeneration. Mineralization can be both induced by the enzyme alkaline phosphatase (ALP) and promoted by calcium-binding biomolecules, such as plant-derived polyphenols. In this study, ALP-loaded gellan gum (GG) hydrogels were enriched with gallotannins, a subclass of polyphenols. Five preparations were compared, namely three tannic acids of differing molecular weight (MW), pentagalloyl glucose (PGG), and a gallotannin-rich extract from mango kernel (Mangifera indica L.). Certain gallotannin preparations promoted mineralization to a greater degree than others. The various gallotannin preparations bound differently to ALP and influenced the size of aggregates of ALP, which may be related to ability to promote mineralization. Human osteoblast-like Saos-2 cells grew in eluate from mineralized hydrogels. Gallotannin incorporation impeded cell growth on hydrogels and did not impart antibacterial activity. In conclusion, gallotannin incorporation aided mineralization but reduced cytocompatibility