Differential gene expression in oyster exposed to sewage     

Medeiros ID  Siebert MN  de Toledo e Silva G  Moraes MO  Marques MR  Bainy AC 《Marine environmental research》2008,66(1):156-157

In order to investigate the influence of domestic sewage on the gene expression of Pacific oysters Crassostrea gigas, suppression subtractive hybridization (SSH) method was employed. Oysters were sampled at a farming area and, after 10 days of acclimation in the laboratory, were exposed to untreated domestic sewage diluted 33% for 48 h. Gills of male oysters were excised for total RNA extraction. mRNA was purified and the differential gene expression was analyzed by SSH. We obtained 61 cDNA sequences but only 15 were identified, which includes fatty acid binding protein, multidrug resistance protein, omega glutathione S-transferase, cytochrome P450 isoform CYP356A1, among others. The identified genes are associated with different metabolic functions like biotransformation, membrane transport, aerobic metabolism and translational machinery, evidencing the potential toxic effects elicited by these effluents.  相似文献   

Comparison of the antioxidant defense system in Crassostrea rhizophorae and Crassostrea gigas exposed to domestic sewage discharges     

Zanette J  Nunes FF  Medeiros ID  Siebert MN  Mattos JJ  Lüchmann KH  Rodrigues de Melo CM  Bainy AC 《Marine environmental research》2008,66(1):196-198

Oysters Crassostrea rhizophorae and Crassostrea gigas were kept for fourteen days at four sites in S?o José, SC, Brazil, chosen according to a sewage discharge contamination gradient. Enzymatic activities of CAT, GST, G6PDH and GR were evaluated in gills and digestive glands. Higher CAT activity was observed in tissues of C. rhizophorae in response to sewage contamination possibly indicating peroxisome proliferation induction. C. gigas showed elevated G6PDH activity in digestive gland, and GR in gills, after domestic sewage exposure. In conclusion, C. rhizophorae and C. gigas showed different biochemical responses after in situ exposure to domestic sewage. However, C. rhizophorae showed more significant changes in CAT suggesting that this organism could be a better monitor to this kind of effluent.  相似文献   

Melting of Fe–Ni–Si and Fe–Ni–S alloys at megabar pressures: implications for the core–mantle boundary temperature     

Guillaume Morard  Denis Andrault  Nicolas Guignot  Julien Siebert  Gaston Garbarino  Daniele Antonangeli 《Physics and Chemistry of Minerals》2011,38(10):767-776

High pressure melting behavior of three Fe-alloys containing 5 wt% Ni and (1) 10 wt% Si, (2) 15 wt% Si or (3) 12 wt% S was investigated up to megabar pressures by in situ X-ray diffraction and laser-heated diamond anvil cell techniques. We observe a decrease in melting temperature with increasing Si content over the entire investigated pressure range. This trend is used to discuss the melting curve of pure Fe. Moreover, our measurements of eutectic melting in the Fe–Fe₃S system show a change in slope around 50 GPa concomitant with the fcc–hcp phase transition in pure solid iron. Extrapolations of our melting curve up to the core–mantle boundary pressure yield values of 3,600–3,750 K for the freezing temperature of plausible outer core compositions.  相似文献   

World Map of Natural Hazards – A Global View of the Distribution and Intensity of Significant Exposures     

Berz  G.  Kron  W.  Loster  T.  Rauch  E.  Schimetschek  J.  Schmieder  J.  Siebert  A.  Smolka  A.  Wirtz  A. 《Natural Hazards》2001,23(2-3):443-465

  相似文献   

Numerical analysis of the groundwater regime in the western Dead Sea escarpment, Israel + West Bank   总被引：2，自引：2，他引：0  

Agnes Gräbe  Tino Rödiger  Karsten Rink  Thomas Fischer  Feng Sun  Wenqing Wang  Christian Siebert  Olaf Kolditz 《Environmental Earth Sciences》2013,69(2):571-585

Water is scarce in the semi-arid to arid regions around the Dead Sea, where water supply mostly relies on restricted groundwater resources. Due to increasing population in this region, the regional aquifer system is exposed to additional stress. This results in the continuous decrease in water level of the adjacent Dead Sea. The interaction of an increasing demand for water due to population growth and the decrease of groundwater resources will intensify in the near future. Thus, the water supply situation could worsen significantly unless sustainable water resource management is conducted. In this study, we develop a regional groundwater flow model of the eastern and southern Judea Group Aquifer to investigate the groundwater regime in the western Dead Sea drainage basin of Israel and the West Bank. An extensive geological database was developed and consequently a high-resolution structural model was derived. This structural model was the basis for various groundwater flow scenarios. The objective was to capture the spatial heterogeneity of the aquifer system and to apply these results to the southern part of the study area, which has not been studied in detail until now. As a result we analyzed quantitatively the flow regime, the groundwater mass balance and the hydraulic characteristics (hydraulic conductivity and hydraulic head) of the cretaceous aquifer system and calibrated them with PEST. The calibrated groundwater flow model can be used for integrated groundwater water management purposes in the Dead Sea area, especially within the framework of the SUMAR-Project.  相似文献   

Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data   总被引：2，自引：2，他引：0  

U. Mallast  C. Siebert  B. Wagner  M. Sauter  R. Gloaguen  S. Geyer  R. Merz 《Environmental Earth Sciences》2013,69(2):587-603

The semi-arid region of the Dead Sea heavily relies on groundwater resources. This dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management. Yet, information on groundwater discharge as one main component for a sustainable management varies significantly in this area. Moreover, discharge locations, volume and temporal variability are still only partly known. A multi-temporal thermal satellite approach is applied to localise and semi-quantitatively assess groundwater discharge along the entire coastline. The authors use 100 Landsat ETM + band 6.2 data, spanning the years between 2000 and 2011. In the first instance, raw data are transformed to sea surface temperature (SST). To account for groundwater intermittency and to provide a seasonally independent data set ?T (maximum SST range) per-pixel within biennial periods is calculated subsequently. Groundwater affected areas (GAA) are characterised by ?T < 8.5 °C. Unaffected areas exhibit values >10 °C. This allows the exact identification of 37 discharge locations (clusters) along the entire Dead Sea coast, which spatially correspond to available in situ discharge observations. Tracking the GAA extents as a direct indicator of groundwater discharge volume over time reveals (1) a temporal variability correspondence between GAA extents and recharge amounts, (2) the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge, (3) a certain variability in discharge locations as a consequence of the Dead Sea level drop, and finally (4) the assumed flushing effect of old Dead Sea brines from the sedimentary body to have occurred at least during the two series of 2000–2001 and 2010–2011.  相似文献   

Kyanite eclogites from the Rietfontein kimberlite pipe,mier coloured reserve,Gordonia, Cape Province,South Africa     

J. J. Gurney  M. Mathias  C. Siebert  G. Moseley 《Contributions to Mineralogy and Petrology》1971,30(1):46-52

The kimberlite pipe at Rietfontein has been found to contain a suite of ultrabasic xenoliths, amongst which are kyanite eclogites of unusual freshness. The kyanite crystals are of varying shades of blue. Physical properties of some of the primary minerals together with the chemical composition of four kyanite eclogites and of a light and a dark blue kyanite crystal are presented.The xenoliths found in the Rietfontein Pipe are compared with those found in the Zagadochnaya Pipe and certain similarities and differences noted.  相似文献   

A kinetic model for distribution coefficients and application to Mg-calcites     

R.W. Lahann  R.M. Siebert 《Geochimica et cosmochimica acta》1982,46(11):2229-2237

A review of experimental and natural Mg-calcite occurrences indicates that no simple relation exists between $\text{mMg}\text{mCa}$ in solution and $\text{X}{}^{\mathrm{Mg}}\text{X}{}^{\mathrm{ca}}$ in growing calcite crystals. The great variability of the data suggests a strong influence of precipitation kinetics on the distribution of Mg⁺² between solution and crystal. We have derived a kinetic formulation for the distribution coefficient (λ^Mg = X^Mg/X_Ca/ mMg/mCa) based upon the existence, at steady state conditions, of a constant mass surface phase. The resulting formulation is consistent with both experimental and natural Mg-calcite compositions. The primary factors which influence the value of λ^Mg are temperature and the ratio of K_sp^MCO3 to the activity product ([M⁺²][CO₃^?2]/[MCO₃]) for magnesite and calcite. The results suggest that Mg-calcite composition (X^Mg/X^Ca) is at best a crude measure of the mMg/mCa ratio in paleosolutions.  相似文献   

A study of garnets from eclogite and peridotite xenoliths found in kimberlite     

P. C. Rickwood  M. Mathias  J. C. Siebert 《Contributions to Mineralogy and Petrology》1968,19(4):271-301

The chemical compositions of garnets from 58 eclogite, 72 peridotite and 4 pyroxenite xenoliths in kimberlites have been estimated from their unit cell edge length and refractive indices. The samples studied were obtained from 17 kimberlite occurrences and include all those of known source which remain in the famous Williams (1932) collection which is stored at the University of Cape Town. Every suitable sample available to the authors has been examined.A gap in the range of garnet volume percentages occurs in the samples studied between approximately 15 and 30%. Garnet peridotites characteristically have <15% garnet and eclogites >30% garnet. Very rare exceptions occur. Our collection contains no eclogites with olivine and only one with orthopyroxene. All but two of the peridotite-pyroxenite group contain orthopyroxene. The garnets from the peridotites and pyroxenites plot on a pyrope-almandine-uvarovite triangle in a narrow band with a remarkably constant almandine/uvarovite ratio. Garnets from the eclogites are plotted on a pyrope-almandine-grossularite triangle and have a wide spread of compositions. These fall into 4 groups viz. eclogite I, eclogite II, kyanite eclogite and corundum eclogite.The reasons for the differences in garnet chemistry are considered and a tentative evolutionary scheme suggested by partial melting of the garnet peridotite which is assumed to occur in the upper mantle. Recent models of upper mantle composition and the genesis of garnet-bearing xenoliths in kimberlite are briefly and critically examined.S.A. UMP Publication No. 9.  相似文献   

Element partitioning between magnesium silicate perovskite and ferropericlase: New insights into bulk lower-mantle geochemistry     

Anne-Line Auzende  James Badro  Frederick J. Ryerson  Peter K. Weber  Stewart J. Fallon  Ahmed Addad  Julien Siebert  Guillaume Fiquet   《Earth and Planetary Science Letters》2008,269(1-2):164-174

In this study, we investigated iron–magnesium exchange and transition-metal trace-element partitioning between magnesium silicate perovskite (Mg,Fe)SiO₃ and ferropericlase (Mg,Fe)O synthetised under lower-mantle conditions (up to 115 GPa and 2200 K) in a laser-heated diamond anvil cell. Recovered samples were thinned to electron transparency by focused ion beam and characterized by analytical transmission electron microscopy (ATEM) and nanometer-scale secondary ion mass spectroscopy (nanoSIMS). Iron concentrations in both phases were obtained from X-ray energy dispersive spectroscopy measurements and nanoSIMS. Our results are the first to show that recently reported spin-state and phase transitions in the lower mantle directly affect the evolution of Fe–Mg exchange between both phases. Mg-perovskite becomes increasingly iron-depleted above 70–80 GPa possibly due to the high spin–low spin transition of iron in ferropericlase. Conversely, the perovskite to post-perovskite transition is accompanied by a strong iron enrichment of the silicate phase, ferropericlase remaining in the Fe-rich phase though. Nanoparticles of metallic iron were observed in the perovskite-bearing runs, suggesting the disproportionation of ferrous iron oxide, but were not observed when the post-perovskite phase was present. Implications on the oxidation state of the Earth and core segregation will be discussed. Transition trace-element (Ni, Mn) concentrations (determined with the nanoSIMS) show similar trends and could thus be used to trace the origin of diamonds generated at depth. This study provides new results likely to improve the geochemical and geophysical models of the Earth's deep interiors.  相似文献