Towards an integrated view on microbial CH4, N2O and N2 cycles in brackish coastal marsh soils: A comparative analysis of two sites.

Coastal ecosystems, facing threats from global change and human activities like excessive nutrients, undergo alterations impacting their function and appearance. This study explores the intertwined microbial cycles of carbon (C) and nitrogen (N), encompassing methane (CH4), nitrous oxide (N2O), and nitrogen gas (N2) fluxes, to determine nutrient transformation processes between the soil-plant-atmosphere continuum in the coastal ecosystems with brackish water. Water salinity negatively impacted denitrification, bacterial nitrification, N fixation, and n-DAMO processes, but did not significantly affect archaeal nitrification, COMAMMOX, DNRA, and ANAMMOX processes in the N cycle. Plant species age and biomass influenced CH4 and N2O emissions. The highest CH4 emissions were from old Spartina and mixed Spartina and Scirpus sites, while Phragmites sites emitted the most N2O. Nitrification and incomplete denitrification mainly governed N2O emissions depending on the environmental conditions and plants. The higher genetic potential of ANAMMOX reduced excessive N by converting it to N2 in the sites with higher average temperatures. The presence of plants led to a decrease in the N fixers' abundance. Plant biomass negatively affected methanogenetic mcrA genes. Microbes involved in n-DAMO processes helped mitigate CH4 emissions. Over 93 % of the total climate forcing came from CH4 emissions, except for the Chinese bare site where the climate forcing was negative, and for Phragmites sites, where almost 60 % of the climate forcing came from N2O emissions. Our findings indicate that nutrient cycles, CH4, and N2O fluxes in soils are context-dependent and influenced by environmental factors and vegetation. This underscores the need for empirical analysis of both C and N cycles at various levels (soil-plant-atmosphere) to understand how habitats or plants affect nutrient cycles and greenhouse gas emissions.

The standardized creation of a lumbar spine vertebral compression fracture in a sheep osteoporosis model induced by ovariectomy, corticosteroid therapy and calcium/phosphorus/vitamin D-deficient diet.

INTRODUCTION: Vertebral compression fractures (VCFs) are one of the most common injuries in the aging population presenting with an annual incidence of 1.4 million new cases in Europe. Current treatment strategies focus on cement-associated solutions (kyphoplasty/vertebroplasty techniques). Specific cement-associated problems as leakage, embolism and the adjacent fracture disease are reported adding to open questions like general fracture healing properties of the osteoporotic spine. In order to analyze those queries animal models are of great interest; however, both technical difficulties in the induction of experimental osteoporosis in animal as well as the lack of a standardized fracture model impede current and future in vivo studies. This study introduces a standardized animal model of an osteoporotic VCF type A3.1 that may enable further in-depth analysis of the afore mentioned topics. MATERIAL AND METHODS: Twenty-four 5-year-old female Merino sheep (mean body weight: 67 kg; range 57-79) were ovariectomized (OP1) and underwent 5.5 months of weekly corticosteroid injections (dexamethasone and dexamethasone-sodium-phosphate), adding to a calcium/phosphorus/vitamin D-deficient diet. Osteoporosis induction was documented by pQCT and micro-CT BMD (bone mineral density) as well as 3D histomorphometric analysis postoperatively of the sheep distal radius and spine. Non osteoporotic sheep served as controls. Induction of a VCF of the second lumbar vertebra was performed via a mini-lumbotomy surgical approach with a standardized manual compression mode (OP2). RESULTS: PQCT analysis revealed osteoporosis of the distal radius with significantly reduced BMD values (0.19 g/cm(3), range 0.13-0.22 vs. 0.27 g/cm(3), range 0.23-0.32). Micro-CT documented significant lowering of BMD values for the second lumbar vertebrae (0.11 g/cm(3), range 0.10-0.12) in comparison to the control group (0.14 g/cm(3), range 0.12-0.17). An incomplete burst fracture type A3.1 was achieved in all cases and resulted in a significant decrease in body angle and vertebral height (KA 4.9°, range: 2-12; SI 4.5%, range: 2-12). With OP1, one minor complication (lesion of small bowel) occurred, while no complications occurred with OP2. CONCLUSIONS: A suitable spinal fracture model for creation of VCFs in osteoporotic sheep was developed. The technique may promote the development of improved surgical solutions for VCF treatment in the experimental and clinical setting.