Effects of oxidative stress on protein thiols and disulphides in Mytilus edulis revealed by proteomics: actin and protein disulphide isomerase are redox targets     

McDonagh B  Sheehan D 《Marine environmental research》2008,66(1):193-195

Many proteins contain cysteines which are sensitive to oxidation. This is sometimes reversible through interaction with glutathione, glutaredoxin or thioredoxin systems making these proteins potential sensors of oxidative stress. In this study we analysed whether there was an increase in mixed disulphide bond (-S-S-) formation in the blue mussel Mytilus edulis in response to menadione. This was achieved by initially blocking reduced thiols with N-ethylmaleimide, -S-S- were then reduced with dithiothreitol (DTT) and labelled with 5-iodoacetamidofluorescein (5-IAF). Free -SHs were also labelled directly with 5-IAF. Separations were performed on 1D or 2D SDS PAGE and images analysed. There was an increase in -S-S- in response to menadione and detection of changes in oxidised proteins was easier than that of changes in the amount of reduced proteins. Protein disulphide isomerase (PDI) was labelled both as -SH and -S-S-, underlining its involvement in the redox status of the animal. A glutathione transferase (GST P1-1) forms an inter-chain disulphide bridge in response to menadione.  相似文献   

Effects of sample size on numerical estimates of diel prey consumption in a fish population     

Brendan C. Ebner  Ryan R.J. McAllister  Phil Suter 《新西兰海洋与淡水研究杂志》2013,47(2):579-590

Numerical data based on stomach content analysis of the zooplanktivorous freshwater fish, Retropinna semoni, were used to examine the effect of fish sample size on mean counts of dominant prey items. Fifty adult R. semoni were collected from throughout the open‐water of Lake Benanee, Australia at each of five times over a diel period. Bootstrapping was used to generate confidence intervals around sample means, and markedly more accurate means were obtained from samples collected in the day than the night. High variation in night samples was the by‐product of a diurnal feeding regime. Traditional sample sizes of 10 to 15 stomachs resulted in reasonable confidence intervals of sample means derived from collections on the first day, corresponding to uniform feeding patterns in the population. However, increased sample sizes were required to describe more complex feeding behaviour on the second day, when a proportion of the population switched to an alternative prey source.  相似文献   

Marine radiocarbon reservoir corrections (∆R) for Chesapeake Bay and the Middle Atlantic Coast of North America     

Torben C. Rick  Gregory A. Henkes  Darrin L. Lowery  Steven M. Colman  Brendan J. Culleton 《Quaternary Research》2012,77(1):205-210

Radiocarbon dates from known age, pre-bomb eastern oyster (Crassostrea virginica) shells provide local marine reservoir corrections (?R) for Chesapeake Bay and the Middle Atlantic coastal area of eastern North America. These data suggest subregional variability in ?R, ranging from 148 ± 46 ¹⁴C yr on the Potomac River to ? 109 ± 38 ¹⁴C yr at Swan Point, Maryland. The ?R weighted mean for the Chesapeake's Western Shore (129 ± 22 ¹⁴C yr) is substantially higher than the Eastern Shore (? 88 ± 23 ¹⁴C yr), with outer Atlantic Coast samples falling between these values (106 ± 46 and 2 ± 46 ¹⁴C yr). These differences may result from a combination of factors, including ¹⁴C-depleted freshwater that enters the bay from some if its drainages, ¹⁴C-depleted seawater that enters the bay at its mouth, and/or biological carbon recycling. We advocate using different subregional ?R corrections when calibrating ¹⁴C dates on aquatic specimens from the Chesapeake Bay and coastal Middle Atlantic region of North America.  相似文献   

First Palaeozoic arachnid from Portugal and implications for Carboniferous palaeobiogeography     

Pedro Correia  J. Brendan Murphy  Artur A. S  Rúben Domingos  Deolinda Flores 《Geological Journal》2013,48(1):101-107

The first occurrence of arachnids (Aphantomartus pustulatus) in the Carboniferous strata of Portugal is documented and its palaeobiogeographic significance is assessed. The Aphantomartidae species are thought to be native to Central Europe where its oldest example is recorded in Middle–Upper Mississippian strata. Known occurrences are preserved along the flanks of mountains such as the Appalachian Mountains, the Cantabrian Mountains and the Valongo Anticline (Portugal, Iberian Massif) and provide clear evidence that the Aphantomartidae species probably lived in upland or mountainous environments. The Iberian Massif may have served as a ‘link’ between the migration routes of several terrestrial animals from North America and Eurasia, and this linkage constrains the palaeogeographic and palaeoenvironmental conditions in equatorial Pangaea during the Carboniferous and Early Permian. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Repurposing climate reconstructions for drought prediction in Southeast Asia     

Andrew?R.?BellEmail author  Benjamin?I.?Cook  Kevin?J.?Anchukaitis  Brendan?M.?Buckley  Edward?R.?Cook 《Climatic change》2011,106(4):691-698

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Evidence for multiple early impacts on the H chondrite parent body from electron backscatter diffraction analysis     

Secana P. Goudy  Myriam Telus  Brendan Chapman 《Meteoritics & planetary science》2023,58(4):501-515

We examined H4 chondrites Beaver Creek, Forest Vale, Quenggouk, Ste. Marguerite, and Sena with the electron backscatter diffraction (EBSD) techniques of Ruzicka and Hugo (2018) to determine if there is evidence for shock metamorphism consistent with the previously inferred histories of their early impact excavation or lack thereof. We find that all samples have EBSD data consistent with a history of synmetamorphic impact shock (i.e., shock during thermal metamorphism), followed by postshock annealing. Petrographic analysis of Sena, Quenggouk, and Ste. Marguerite found exsolved Cu and irregular troilite within Fe metal, features consistent with shock metamorphism. All samples have a spatial variability in grain deformation consistent with shock processes, though Forest Vale, Quenggouk, and Ste. Marguerite may have relict signatures of accretional deformation as indicated by variability in their olivine deformation metrics. Within the context of previous workers' geochemical observations, a more complex history is inferred for each sample. The “slow-cooled” samples, Quenggouk and Sena, were subject to synmetamorphic shock without excavation and annealed at depth. The same is true of the “fast-cooled” samples, Beaver Creek, Forest Vale, and Ste. Marguerite. However, after annealing, these rocks were excavated by a secondary impact or impacts around 5.2–6.5 Ma post-CAI formation and were left to cool rapidly on the surface of the H chondrite parent body. These interpreted histories are best compatible with a model of an impact-battered but intact onion shell for the earliest history of the H parent body. However, the EBSD evidence does not preclude a parent body disruption after 7 Ma post-CAI formation.  相似文献   

Changing mantle sources in a suture zone in the heart of Pangea: implications for collisional tectonics during the waning stages of ocean closure     

Nicolle E. Dupuis  James A. Braid  J. Brendan Murphy  Cecilio Quesada  Chris McFarlane 《International Journal of Earth Sciences》2014,103(5):1403-1414

The formation and emplacement of syn-collisional mafic dykes that intrude suture zones and their association with orogenic processes are enigmatic. Southern Iberia records the Late Paleozoic amalgamation of Pangea and exposes today a fragment of Laurussia (South Portuguese Zone), which is spatially juxtaposed with autochthonous Gondwana. Fault-bounded oceanic metasedimentary rocks, mélanges and ophiolite complexes characterize the suture zone and are in turn crosscut by intrusive granitoid rocks and mafic dykes. The generation and emplacement of these mafic dykes and their relationship to the suture zone are undetermined. Field evidence shows the dykes were emplaced at high angles to pre-existing orogenic fabrics in the mélange, granitoid and metasedimentary rocks. Geochemical analyses (major, trace, rare earth elements) indicate the dykes exhibit a mid-ocean ridge basalt signature. U/Pb zircon geochronology reveals the crystallization age of the dykes is ca. 316 Ma and Sm–Nd isotopic analysis suggests a deep mantle source. Taken together, these data support existing temporal constraints on events leading up to the amalgamation of Pangea, and suggest progressive lower crustal delamination during the waning stages of continent–continent collision.  相似文献   

Geochemistry of the Peramora Mélange and Pulo do Lobo schist: geochemical investigation and tectonic interpretation of mafic mélange in the Pangean suture zone,Southern Iberia     

Dustin R. L. Dahn  James A. Braid  J. Brendan Murphy  Cecilio Quesada  Nicole Dupuis  Christopher R. M. McFarlane 《International Journal of Earth Sciences》2014,103(5):1415-1431

The Peramora Mélange is part of an accretionary complex between the South Portuguese Zone (a fragment of Laurussia) and the Ossa Morena Zone (para-autochthonous Gondwana) and is an expression of the Pangean suture zone in southwestern Iberia. The suture zone is characterized by fault-bounded units of metasedimentary rocks, mélanges, and mafic complexes. Detailed geologic mapping of the Peramora Mélange reveals a complex pattern of imbricated schists and mafic block-in-matrix mélanges. Geochemical signatures of the Pulo do Lobo schist (PDL) are consistent with derivation from both mafic and continental sources. The mafic block-in-matrix mélange displays normal mid-ocean ridge basalt (NMORB) geochemical signature, juvenile Sm–Nd isotopic compositions, and a range of zircon ages similar to those observed in the PDL, suggesting a sedimentary component. Taken together, these data suggest a complex tectonic history characterized by erosion of a NMORB source, mélange formation, and imbrication during underplating occurring during the final stages of continent–continent collision.  相似文献   

U–Pb geochronology and petrology of the late Paleozoic Gil Marquez pluton: magmatism in the Variscan suture zone,southern Iberia,during continental collision and the amalgamation of Pangea     

Evan R. Gladney  James A. Braid  J. Brendan Murphy  Cecilio Quesada  Christopher R. M. McFarlane 《International Journal of Earth Sciences》2014,103(5):1433-1451

The origin of plutonic complexes that stitch suture zones developed during collision is not well understood. In southern Iberia, the Pulo du Lobo suture zone (PDLZ) is intruded by the syn- to postcollisional Gil Marquez pluton (GMP), thought to be part of the Sierra Norte Batholith. U–Pb (LA-ICPMS, zircon) data on various phases of the GMP yield from oldest to youngest: (1) a 354.4 ± 7.6 Ma unfoliated gabbro; (2) a 345.6 ± 2.5 Ma foliated intermediate phase; (3) a 346.5 ± 5.4 Ma unfoliated porphyritic granite; (4) a 335.1 ± 2.8 Ma unfoliated biotite granite. This sequence is consistent with cross-cutting relationships observed in the field. The range in ages is consistent with interpretations that the GMP is part of the composite (ca. 350–308 Ma) SNB. Inherited ages preserved in the GMP intermediate and felsic phases indicate that its magmas traversed through South Portuguese Zone and PDLZ crust during emplacement. The ca. 345 Ma emplacement of the late kinematic foliated intermediate phase constrains the age of late-stage strike slip deformation within the PDLZ, and the lack of a foliation in the older gabbro indicates that is was not proximal to a shear zone neither at the time of emplacement, nor during its subsequent history. The unfoliated porphyritic granite and unfoliated biotite granite cut the foliation of the intermediate phase indicating emplacement during the waning stages of collision, while the ca. 335 Ma biotite granite intrudes the Santa Ira Flysch, thereby providing a tight constraint for the latest stage of deformation in the PDLZ.  相似文献   

Nitrogen loading to Pleasant Bay, Cape Cod: application of models and stable isotopes to detect incipient nutrient enrichment of estuaries   总被引：1，自引：0，他引：1  

Carmichael RH  Annett B  Valiela I 《Marine pollution bulletin》2004,48(1-2):137-143

To test and refine methods to detect nutrient enrichment and resulting eutrophication, we applied the Waquoit Bay nitrogen loading model (NLM) and Estuarine loading model (ELM) to estuaries of Pleasant Bay that receive increasing but low N loads (25-199 kg N ha(-1) yr(-1)) from land. Contributions of wastewater to these estuaries increased from 7% to 63% as N loads increased, and modeled estimates of dissolved inorganic nitrogen in the water were within approximately 27% of measured values. N isotopic signatures in suspended and benthic organic matter and in tissue of quahogs increased as wastewater contributions to N loads increased, with clams approximately 4 per thousand heavier than organic matter, indicating that even at these low N loads, N from land-derived sources moved detectably up the food web. These results extend the application of NLM and ELM to detect incipient levels of N enrichment and demonstrate that these models can be used in conjunction with isotope measurements as the basis for food web analyses in a system exposed to relatively lower N loads than previously studied.  相似文献