74 research outputs found

    Oxygen dynamics in shelf seas sediments incorporating seasonal variability

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    Shelf sediments play a vital role in global biogeochemical cycling and are particularly important areas of oxygen consumption and carbon mineralisation. Total benthic oxygen uptake, the sum of diffusive and faunal mediated uptake, is a robust proxy to quantify carbon mineralisation. However, oxygen uptake rates are dynamic, due to the diagenetic processes within the sediment, and can be spatially and temporally variable. Four benthic sites in the Celtic Sea, encompassing gradients of cohesive to permeable sediments, were sampled over four cruises to capture seasonal and spatial changes in oxygen dynamics. Total oxygen uptake (TOU) rates were measured through a suite of incubation experiments and oxygen microelectrode profiles were taken across all four benthic sites to provide the oxygen penetration depth and diffusive oxygen uptake (DOU) rates. The difference between TOU and DOU allowed for quantification of the fauna mediated oxygen uptake and diffusive uptake. High resolution measurements showed clear seasonal and spatial trends, with higher oxygen uptake rates measured in cohesive sediments compared to the permeable sediment. The significant differences in oxygen dynamics between the sediment types were consistent between seasons, with increasing oxygen consumption during and after the phytoplankton bloom. Carbon mineralisation in shelf sediments is strongly influenced by sediment type and seasonality

    Investigation of Model Cell Membranes with Raman Spectroscopy: A Biochemistry Laboratory Experiment

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    New developments that extend the usefulness of Raman spectroscopy for the investigation of biological systems are described. One of these methods, excitation with a near-infrared laser at 1064 nm and detection with a Fourier transform infrared spectrometer, is applied to the investigation of temperature profiles of dispersions of phospholipids in water. These dispersions are models of biomembranes. This experiment for the undergraduate biochemisty laboratory gives students experience applying vibrational spectroscopy to the investigation of the molecular properties of biomembranes. The basis of the Raman effect is reviewed

    Investigation of Model Cell Membranes with Raman Spectroscopy: A Biochemistry Laboratory Experiment

    No full text
    New developments that extend the usefulness of Raman spectroscopy for the investigation of biological systems are described. One of these methods, excitation with a near-infrared laser at 1064 nm and detection with a Fourier transform infrared spectrometer, is applied to the investigation of temperature profiles of dispersions of phospholipids in water. These dispersions are models of biomembranes. This experiment for the undergraduate biochemisty laboratory gives students experience applying vibrational spectroscopy to the investigation of the molecular properties of biomembranes. The basis of the Raman effect is reviewed

    Toxicological effects assessment for wildlife in the 21st century: Review of current methods and recommendations for a path forward

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    Model species (e.g., granivorous gamebirds, waterfowl, passerines, domesticated rodents) have been used for decades in guideline laboratory tests to generate survival, growth, and reproductive data for prospective ecological risk assessments (ERAs) for birds and mammals, while officially adopted risk assessment schemes for amphibians and reptiles do not exist. There are recognized shortcomings of current in vivo methods as well as uncertainty around the extent to which species with different life histories (e.g., terrestrial amphibians, reptiles, bats) than these commonly used models are protected by existing ERA frameworks. Approaches other than validating additional animal models for testing are being developed, but the incorporation of such new approach methodologies (NAMs) into risk assessment frameworks will require robust validations against in vivo responses. This takes time, and the ability to extrapolate findings from nonanimal studies to organism‐ and population‐level effects in terrestrial wildlife remains weak. Failure to adequately anticipate and predict hazards could have economic and potentially even legal consequences for regulators and product registrants. In order to be able to use fewer animals or replace them altogether in the long term, vertebrate use and whole organism data will be needed to provide data for NAM validation in the short term. Therefore, it is worth investing resources for potential updates to existing standard test guidelines used in the laboratory as well as addressing the need for clear guidance on the conduct of field studies. Herein, we review the potential for improving standard in vivo test methods and for advancing the use of field studies in wildlife risk assessment, as these tools will be needed in the foreseeable future
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