Sulfur cycle imbalance and environmental change during the Ediacaric Period

A different approach is proposed here to solve the problem of negative chemostratigraphic excursions during the Ediacárico, considering them in terms of a linked system of carbon-sulfide-oxygen, in which changes in the dynamics of oxidants would cause an excess of oxidation of organic carbon over the burial, which would result in a smaller deposit of DOM. The amount of oxidant required to achieve a negative carbon isotopic excursion through the oxidation of net organic carbon can reasonably result from the evaporitaa solution at the basin scale

Sulfur cycle imbalance and environmental change during the Ediacaran Period = Desequilibrio del ciclo del azufre y cambio ambiental durante el Período Ediacárico

A different approach is proposed here to solve the problem of negative δ13C excursions during the Ediacaran, by viewing them in terms of a linked carbon-sulfur-oxygen system, whereby changes in oxidant dynamics caused an excess of organic carbon oxidation over burial, resulting in a smaller DOM reservoir. The amount of oxidant required to achieve a deep negative carbon isotope excursion through net organic carbon oxidation may reasonably result from basin-scale evaporite dissolution. / Se propone aquí un enfoque diferente para resolver el problema de las excursiones quimioestratigráficas negativas durante el Ediacárico, considerándolas en términos de un sistema vinculado de carbono-sulfuro-oxígeno, en el que los cambios en la dinámica de los oxidantes causarían un exceso de oxidación de carbono orgánico sobre el enterramiento, lo que resultaría en un depósito menor de DOM. La cantidad de oxidante requerida para lograr una excursión isotópica de carbono negativa a través de la oxidación de carbono orgánico neto puede resultar razonablemente de la disolución de evaporitaa a escala de cuenca

Cambrian stratigraphy of the St. Valentines Peak area, north-western Tasmania

An important Late Middle Cambrian fossil locality occurs 2 km west of St. Valentines Peak in north-western Tasmania. The Cambrian rocks to the north and west of St. Valentines Peak are exposed in the core of the north-south trending St. Valentines Peak Anticline. In the best exposed section (3 km north of the main fossil locality), the oldest Cambrian unit is a massive, cherty, pyritic meta-sandstone and meta-siltstone at least 100 m thick. This is overlain by 100 m of rhyolitic welded tuff, 75 to 100 m of meta-sandstones and meta-siltstones, 100 m of a possible contact metasomatic rock and 230 to 375 m of a pale grey chert which in turn is overlain by about 17 m of fine breccia and poorly fossiliferous siltstone. This sequence is overlain with probable disconformity by the basal chert conglomerate of the essentially Ordovician Junee Group. It is suggested that the sediments of the main fossiliferous locality occur stratigraphically below the section noted above. The Cambrian and Ordovician rocks are intruded by Devonian granite and partly overlain by Tertiary basalt

Altered expression of caspases-4 and -5 during inflammatory bowel disease and colorectal cancer : diagnostic and therapeutic potential

Caspases are a group of proteolytic enzymes involved in the co-ordination of cellular processes, including cellular homeostasis, inflammation and apoptosis. Altered activity of caspases, particularly caspase-1, has been implicated in the development of intestinal diseases, such as inflammatory bowel disease (IBD) and colorectal cancer (CRC). However, the involvement of two related inflammatory caspase members, caspases-4 and -5, during intestinal homeostasis and disease has not yet been established. This study demonstrates that caspases-4 and -5 are involved in IBD-associated intestinal inflammation. Furthermore, we found a clear correlation between stromal caspase-4 and -5 expression levels, inflammation and disease activity in ulcerative colitis patients. Deregulated intestinal inflammation in IBD patients is associated with an increased risk of developing CRC. We found robust expression of caspases-4 and -5 within intestinal epithelial cells, exclusively within neoplastic tissue, of colorectal tumours. An examination of adjacent normal, inflamed and tumour tissue from patients with colitis-associated CRC confirmed that stromal expression of caspases-4 and -5 is increased in inflamed and dysplastic tissue, while epithelial expression is restricted to neoplastic tissue. In addition to identifying caspases-4 and -5 as potential targets for limiting intestinal inflammation, this study has identified epithelial-expressed caspases-4 and -5 as biomarkers with diagnostic and therapeutic potential in CRC

Comparison of proteomic profiles in the zebrafish retina during experimental degeneration and regeneration

Zebrafish spontaneously regenerate the retina after injury. Although the gene expression profile has been extensively studied in this species during regeneration, this does not reflect protein function. To further understand the regenerative process in the zebrafish, we compared the proteomic profile of the retina during injury and upon regeneration. Using two-dimensional difference gel electrophoresis (2D-DIGE) and label-free quantitative proteomics (quadrupole time of flight LC-MS/MS), we analysed the retina of adult longfin wildtype zebrafish at 0, 3 and 18 days after Ouabain injection. Gene ontology analysis indicates reduced metabolic processing, and increase in fibrin clot formation, with significant upregulation of fibrinogen gamma polypeptide, apolipoproteins A-Ib and A-II, galectin-1, and vitellogenin-6 during degeneration when compared to normal retina. In addition, cytoskeleton and membrane transport proteins were considerably altered during regeneration, with the highest fold upregulation observed for tubulin beta 2 A, histone H2B and brain type fatty acid binding protein. Key proteins identified in this study may play an important role in the regeneration of the zebrafish retina and investigations on the potential regulation of these proteins may lead to the design of protocols to promote endogenous regeneration of the mammalian retina following retinal degenerative disease

Symptoms and patient factors associated with diagnostic intervals for pancreatic cancer (SYMPTOM pancreatic study): a prospective cohort study

This is the final version. Available on open access from Elsevier via the DOI in this recordBackground Pancreatic cancer is the tenth most common cancer in the UK; however, outcomes are poor, in part due to late diagnosis. We aimed to identify symptoms and other clinical and sociodemographic factors associated with pancreatic cancer diagnosis and diagnostic intervals. Methods We did this prospective cohort study at seven hospitals in two regions in England. We recruited participants aged 40 years or older who were referred for suspicion of pancreatic cancer. Data were collected by use of a patient questionnaire and primary care and hospital records. Descriptive and regression analyses were done to examine associations between symptoms and patient factors with the total diagnostic interval (time from onset of the first symptom to the date of diagnosis), comprising patient interval (time from first symptom to first presentation) and health system interval (time from first presentation to diagnosis). Findings We recruited 391 participants between Jan 1, 2011, and Dec 31, 2014 (24% response rate). 119 (30%) participants were diagnosed with pancreatic cancer (41 [34%] had metastatic disease), 47 (12%) with other cancers, and 225 (58%) with no cancer. 212 (54%) patients had multiple first symptoms whereas 161 (41%) patients had a solitary first symptom. In this referred population, no initial symptoms were reported more frequently by patients with cancer than by those with no cancer. Several subsequent symptoms predicted pancreatic cancer: jaundice (51 [49%] of 105 patients with pancreatic cancer vs 25 [12%] of 211 patients with no cancer; p<0·0001), fatigue (48/95 [51%] vs 40/155 [26%]; p=0·0001), change in bowel habit (36/87 [41%] vs 28/175 [16%]; p<0·0001), weight loss (55/100 [55%] vs 41/184 [22%]; p<0·0001), and decreased appetite (41/86 [48%] vs 41/156 [26%]; p=0·0011). There was no difference in any interval between patients with pancreatic cancer and those with no cancer (total diagnostic interval: median 117 days [IQR 57–234] vs 131 days [IQR 66–284]; p=0·32; patient interval 18 days [0–37] vs 15 days [1–62]; p=0·22; health system interval 76 days [28–161] vs 79 days [30–156]; p=0·68). Total diagnostic intervals were shorter when jaundice (hazard ratio [HR] 1·38, 95% CI 1·07–1·78; p=0·013) and decreased appetite (1·42, 1·11–1·82; p=0·0058) were reported as symptoms, and longer in patients presenting with indigestion (0·71, 0·56–0·89; p=0·0033), back pain (0·77, 0·59–0·99; p=0·040), diabetes (0·71, 0·52–0·97; p=0·029), and self-reported anxiety or depression, or both (0·67, 0·49–0·91; p=0·011). Health system intervals were likewise longer with indigestion (0·74, 0·58–0·95; p=0·0018), back pain (0·76, 0·58–0·99; p=0·044), diabetes (0·63, 0·45–0·89; p=0·0082), and self-reported anxiety or depression, or both (0·63, 0·46–0·88; p=0·0064), but were shorter with male sex (1·41, 1·1–1·81; p=0·0072) and decreased appetite (1·56, 1·19–2·06; p=0·0015). Weight loss was associated with longer patient intervals (HR 0·69, 95% CI 0·54–0·89; p=0·0047). Interpretation Although we identified no initial symptoms that differentiated people diagnosed with pancreatic cancer from those without pancreatic cancer, key additional symptoms might signal the disease. Health-care professionals should be vigilant to the possibility of pancreatic cancer in patients with evolving gastrointestinal and systemic symptoms, particularly in those with diabetes or mental health comorbidities. Funding National Institute for Health Research and Pancreatic Cancer Action.National Institute for Health Research (NIHR

A short-lived oxidation event during the early Ediacaran and delayed oxygenation of the Proterozoic ocean

The Ediacaran Period was characterised by major carbon isotope perturbations. The most extreme of these, the ∼570 Ma Shuram/DOUNCE (Doushantuo Negative Carbon isotope Excursion) anomaly, coincided with early radiations of benthic macrofauna linked to a temporary expansion in the extent of oxygenated seawater. Here we document an earlier negative excursion (the ∼610 Ma WANCE (Weng'An Negative Carbon isotope Excursion)) anomaly in the Yangtze Gorges area, South China, that reached equally extreme carbon isotope values and was associated with a similar degree of environmental perturbation. Specifically, new uranium isotope data evidence a significant, but transient, shift towards more oxygenated conditions in tandem with decreasing carbon isotope values, while strontium and sulfur isotope data support an increase in continental weathering through the excursion. We utilize a biogeochemical modelling approach to demonstrate that the influx of such a weathering pulse into an organically-laden, largely anoxic ocean, fully reproduces each of these distinct isotopic trends. Our study directly supports the hypothesis that a large dissolved marine organic pool effectively buffered against widespread oxygenation of the marine environment through the Proterozoic Eon, and in doing so, substantially delayed the radiation of complex aerobic life on Earth

Modelling the long-term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day

Over geological timescales, CO2 levels are determined by the operation of the long term carbon cycle, and it is generally thought that changes in atmospheric CO2 concentration have controlled variations in Earth's surface temperature over the Phanerozoic Eon. Here we compile independent estimates for global average surface temperature and atmospheric CO2 concentration, and compare these to the predictions of box models of the long term carbon cycle COPSE and GEOCARBSULF. We find a strong relationship between CO2 forcing and temperature from the proxy data, for times where data is available, and we find that current published models reproduce many aspects of CO2 change, but compare poorly to temperature estimates. Models are then modified in line with recent advances in understanding the tectonic controls on carbon cycle source and sink processes, with these changes constrained by modelling 87Sr/86Sr ratios. We estimate CO2 degassing rates from the lengths of subduction zones and rifts, add differential effects of erosion rates on the weathering of silicates and carbonates, and revise the relationship between global average temperature changes and the temperature change in key weathering zones. Under these modifications, models produce combined records of CO2 and temperature change that are reasonably in line with geological and geochemical proxies (e.g. central model predictions are within the proxy windows for >~75% of the time covered by data). However, whilst broad long-term changes are reconstructed, the models still do not adequately predict the timing of glacial periods. We show that the 87Sr/86Sr record is largely influenced by the weathering contributions of different lithologies, and is strongly controlled by erosion rates, rather than being a good indicator of overall silicate chemical weathering rates. We also confirm that a combination of increasing erosion rates and decreasing degassing rates over the Neogene can cause the observed cooling and Sr isotope changes without requiring an overall increase in silicate weathering rates. On the question of a source or sink dominated carbon cycle, we find that neither alone can adequately reconstruct the combination of CO2, temperature and strontium isotope dynamics over Phanerozoic time, necessitating a combination of changes to sources and sinks. Further progress in this field relies on >108 year dynamic spatial reconstructions of ancient tectonics, paleogeography and hydrology. Whilst this is a significant challenge, the latest reconstruction techniques, proxy records and modelling advances make this an achievable target

Spatial housing economics: a survey

This introduction to the Virtual Special Issue surveys the development of spatial housing economics from its roots in neo-classical theory, through more recent developments in social interactions modelling, and touching on the role of institutions, path dependence and economic history. The survey also points to some of the more promising future directions for the subject that are beginning to appear in the literature. The survey covers elements hedonic models, spatial econometrics, neighbourhood models, housing market areas, housing supply, models of segregation, migration, housing tenure, sub-national house price modelling including the so-called ripple effect, and agent-based models. Possible future directions are set in the context of a selection of recent papers that have appeared in Urban Studies. Nevertheless, there are still important gaps in the literature that merit further attention, arising at least partly from emerging policy problems. These include more research on housing and biodiversity, the relationship between housing and civil unrest, the effects of changing age distributions - notably housing for the elderly - and the impact of different international institutional structures. Methodologically, developments in Big Data provide an exciting framework for future work

Biological diversification linked to environmental stabilization following the Sturtian Snowball glaciation

The body fossil and biomarker records hint at an increase in biotic complexity between the two Cryogenian Snowball Earth episodes (ca. 661 million to ≤650 million years ago). Oxygen and nutrient availability can promote biotic complexity, but nutrient (particularly phosphorus) and redox dynamics across this interval remain poorly understood. Here, we present high-resolution paleoredox and phosphorus phase association data from multiple globally distributed drill core records through the non-glacial interval. These data are first correlated regionally by litho- and chemostratigraphy, and then calibrated within a series of global chronostratigraphic frameworks. The combined data show that regional differences in postglacial redox stabilization were partly controlled by the intensity of phosphorus recycling from marine sediments. The apparent increase in biotic complexity followed a global transition to more stable and less reducing conditions in shallow to mid-depth marine environments and occurred within a tolerable climatic window during progressive cooling after post-Snowball super-greenhouse conditions