Sea-level rise will likely accelerate rock coast cliff retreat rates

Coastal response to anthropogenic climate change is of central importance to the infrastructure and inhabitants in these areas. Despite being globally ubiquitous, the stability of rock coasts has been largely neglected, and the expected acceleration of cliff erosion following sea-level rise has not been tested with empirical data, until now. We have optimised a coastal evolution model to topographic and cosmogenic radionuclide data to quantify cliff retreat rates for the past 8000 years and forecast rates for the next century. Here we show that rates of cliff retreat will increase by up to an order of magnitude by 2100 according to current predictions of sea-level rise: an increase much greater than previously predicted. This study challenges conventional coastal management practices by revealing that even historically stable rock coasts are highly sensitive to sea-level rise and should be included in future planning for global climate change response

Dynamic simulations on the mitochondrial fatty acid Beta-oxidation network

<p>Abstract</p> <p>Background</p> <p>The oxidation of fatty acids in mitochondria plays an important role in energy metabolism and genetic disorders of this pathway may cause metabolic diseases. Enzyme deficiencies can block the metabolism at defined reactions in the mitochondrion and lead to accumulation of specific substrates causing severe clinical manifestations. Ten of the disorders directly affecting mitochondrial fatty acid oxidation have been well-defined, implicating episodic hypoketotic hypoglycemia provoked by catabolic stress, multiple organ failure, muscle weakness, or hypertrophic cardiomyopathy. Additionally, syndromes of severe maternal illness (HELLP syndrome and AFLP) have been associated with pregnancies carrying a fetus affected by fatty acid oxidation deficiencies. However, little is known about fatty acids kinetics, especially during fasting or exercise when the demand for fatty acid oxidation is increased (catabolic stress).</p> <p>Results</p> <p>A computational kinetic network of 64 reactions with 91 compounds and 301 parameters was constructed to study dynamic properties of mitochondrial fatty acid β-oxidation. Various deficiencies of acyl-CoA dehydrogenase were simulated and verified with measured concentrations of indicative metabolites of screened newborns in Middle Europe and South Australia. The simulated accumulation of specific acyl-CoAs according to the investigated enzyme deficiencies are in agreement with experimental data and findings in literature. Investigation of the dynamic properties of the fatty acid β-oxidation reveals that the formation of acetyl-CoA – substrate for energy production – is highly impaired within the first hours of fasting corresponding to the rapid progress to coma within 1–2 hours. LCAD deficiency exhibits the highest accumulation of fatty acids along with marked increase of these substrates during catabolic stress and the lowest production rate of acetyl-CoA. These findings might confirm gestational loss to be the explanation that no human cases of LCAD deficiency have been described.</p> <p>Conclusion</p> <p>In summary, this work provides a detailed kinetic model of mitochondrial metabolism with specific focus on fatty acid β-oxidation to simulate and predict the dynamic response of that metabolic network in the context of human disease. Our findings offer insight into the disease process (e.g. rapid progress to coma) and might confirm new explanations (no human cases of LCAD deficiency), which can hardly be obtained from experimental data alone.</p

Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency

Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1. yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS

Actinides AMS on the VEGA accelerator

The VEGA 1MV accelerator at ANSTO is designed to be a highly versatile AMS instrument. In this paper we focus on describing those aspects of the system that are designed to optimise its performance for actinides isotopic analysis, in particular the implementation of fast isotope cycling and multiple isotope detection methods to enable isotope detection across a wide range of rates and currents. Charge state yields are reported in the energy range from 0.3 to 1.0 MeV with helium gas stripping, showing that the highest yield for the 3+ charge state occurs around 1 MeV and exceeds 40%. Accuracy and precision for uranium isotope ratios are shown to approach 1% over a wide range of concentrations and isotope ratios. The ionisation efficiency for plutonium is shown to exceed 3%, leading to overall detection efficiency over 1%. In the absence of background, this leads to sub-attogram detection limits for several Pu isotopes including244Pu

Actinides AMS on the VEGA accelerator

The VEGA 1MV accelerator at ANSTO is designed to be a highly versatile AMS instrument. In this paper we focus on describing those aspects of the system that are designed to optimise its performance for actinides isotopic analysis, in particular the implementation of fast isotope cycling and multiple isotope detection methods to enable isotope detection across a wide range of rates and currents. Charge state yields are reported in the energy range from 0.3 to 1.0 MeV with helium gas stripping, showing that the highest yield for the 3+ charge state occurs around 1 MeV and exceeds 40%. Accuracy and precision for uranium isotope ratios are shown to approach 1% over a wide range of concentrations and isotope ratios. The ionisation efficiency for plutonium is shown to exceed 3%, leading to overall detection efficiency over 1%. In the absence of background, this leads to sub-attogram detection limits for several Pu isotopes including 244Pu.We acknowledge the financial support from the Australian Government for the Centre for Accelerator Science at ANSTO through the National Collaborative Research Infrastructure Strategy (NCRIS)

Al-26/Be-10 ratios reveal the source of river sediments in the Kimberley, NW Australia

We use cosmogenic 10Be and 26Al in both bedrock and fluvial sediments to investigate controls on erosion rates and sediment supply to river basins at the regional scale in the Kimberley, NW Australia. The area is characterised by lithologically controlled morphologies such as cuestas, isolated mesas and extensive plateaus made of slightly dipping, extensively jointed sandstones. All sampled bedrock surfaces at plateau tops, ridgelines, and in the broader floodplain of major rivers over the region show similar slow lowering rates between 0.17 and 4.88 m.Myr‐1, with a mean value of 1.0 ± 0.6 m.Myr‐1 (n=15), whilst two bedrock samples collected directly within river‐beds record rates that are one to two orders of magnitude higher (14.4 ± 1.5 and 20.9 ± 2.5 m.Myr‐1, respectively). Bedrock 26Al/10Be ratios are all compatible with simple, continuous sub‐aerial exposure histories. Modern river sediment yield lower 10Be and 26Al concentrations, apparent 10Be basin‐wide denudation rates ranging between 1.8 and 7.7 m.Myr‐1, with a median value of 2.6 m.Myr‐1, more than double the magnitude of bedrock erosion rates. 26Al/10Be ratios of the sediment samples are lower than those obtained for bedrock samples. We propose that these depleted 26Al/10Be ratios can largely be explained by the supply of sediment to river basins from the slab fragmentation and chemical weathering of channel gorge walls and plateau escarpments that result in diluting the cosmogenic nuclide concentration in river sediments measured at the basin outlets. The results of a mass‐balance model suggest that ~60-90% of river sediment in the Kimberley results from the breakdown and chemical weathering of retreating vertical sandstone rock‐walls in contrast to sediment generated by bedrock weathering and erosion on the plateau tops. This study emphasises the value of analysing two or more isotopes in basin‐scale studies using cosmogenic nuclides, especially in slowly eroding post‐orogenic settings

SIRIUS Performance: 10Be, 26 Al and 36Cl measurements at ANSTO

SIRIUS - a 6 MV pelletron accelerator at ANSTO was delivered and installed in 2014-2015. After initial testing and commissioning phase we have now moved into routine operations. Quality assurance data from the past 2 years demonstrates the excellent performance and SIRIUS is now our preferred instrument for 10 Be, 26 Al and 36 Cl analyses

Soil production and transport on postorogenic desert hillslopes quantified with\u3csup\u3e10\u3c/sup\u3eBe and \u3csup\u3e26\u3c/sup\u3eAl

Hillslopes stand at the top of the geomorphic conveyor belt that produces and transports mass throughout landscapes. Quantification of the tempo of hillslope evolution is key to identifying primary sediment production and understanding how surface processes shape topography. We measured cosmogenic 10 Be and 26 Al on three desert hillslopes in postorogenic central Australia and quantified their soil dynamics and evolution. We found that hillslope morphology is governed by lithological factors, and differing nuclide abundances reflect the main sediment transport processes. Slope wash is widespread, and shrink-swell soil processes drive downslope creep and upward migration of gravels detached from underlying bedrock. We applied Monte Carlo-based inversion modeling to reconstruct soil production and the exhumation histories of stony mantle gravels. Underlying silty soils derive from eolian dust inputs dating to at least 0.2 Ma and possibly more than 1 Ma, in line with intensified aridity. Exposed bedrock erodes at ~0.2-7 m/m.y., and under soil, it erodes at maximum rates of \u3c 0.1 m/m.y. up to 10 m/m.y. Accordingly, particles spend 2-6 m.y. or more in the upper 0.6 m of the bedrock column and an additional ~0.2-2 m.y. or more within hillslope soils. Such long periods near the surface result in surface particles acquiring inherently low 26 Al/ 10 Be ratios. Bedrock erodibility underpins regional variations in erosion rate, and the slow tempo of hillslope evolution is largely independent of base level. This suggests a distinctive top-down evolution among postorogenic hillslopes set by authigenic rates of sediment production, rather than by fluvial incision as in tectonically active settings

An early glacial maximum during the last glacial cycle on the northern Velebit Mt. (Croatia)

Comprehensive glacial Quaternary studies involving geochronological methods, modelling of ice topography with the support of field geomorphological and geological data in the Balkan Peninsula are relatively scarce, although there is evidence of past glaciations in severalmountain ranges. Here, we present research on the extent and timing of past glaciations on the northern Velebit Mt. in coastal Croatia and inferences of the climate during that time. Based on geomorphological and sedimentological evidence and using cosmogenic 36Cl surface exposure dating of moraine boulders, we provide an empirical reconstruction of past glaciers and compare this with the Parallel Ice Sheet Model (PISM) simulations under different palaeoclimate forcings. The dating results show that the northern Velebit glaciers reached their maximum extent during the last glacial cycle before the global Last Glacial Maximum (LGM). Maximum ice extent likely correlates with Marine Isotope Stage 5–4, although the exact timing cannot be determined at this point due to poorly known site- and time-specific denudation rates. Empirical reconstruction of the maximum extent suggests that the area covered by glaciers was ~116 km2. The-best fit PISM simulation indicates that the most likely palaeoclimate scenario for the glaciers of this size to form is a cooling of ~8 °C and a 10% reduction in precipitation from present-day levels. However, the best-fit simulation does not correctly model all mapped ice margins when changes in climatological parameters are applied uniformly across the model domain, potentially reflecting a different palaeoprecipitation pattern to today