Lead contamination of small cetaceans in European waters--the use of stable isotopes for identifying the sources of lead exposure

Lead concentrations and isotopic composition have been measured in bone and teeth of small cetaceans belonging to three species (Delphinus delphis, Phocoena phocoena and Stenella coeruleoalba), to evaluate the toxicological risk and to determine sources of lead in the European waters. Lead concentrations, far lower than threshold value inducing toxic effects in human, were higher in teeth than in bones, but highly correlated between the two tissues (r=0.92, p<0.001). Large variations of 206Pb/207Pb values in bone tissue showed that cetaceans must be submitted to various atmospheric influences. No geographical differences appeared which is consistent with studies on their distribution indicating seasonal movements between Brittany waters and the Bay of Biscay. The negative correlation between 206Pb/207Pb ratios and age of the individuals reflected the decrease in the production of alkyl lead in Europe, i.e., the increasing use of unleaded gasoline.     

Effects of cadmium, zinc and nitrogen status on non-protein thiols in the macroalgae Enteromorpha spp. from the Scheldt Estuary (SW Netherlands, Belgium) and Thermaikos Gulf (N Aegean Sea, Greece)

Enteromorpha prolifera (Scheldt Estuary) and E. linza (Thermaikos Gulf) were incubated at three salinities with 100 and 200microgL(-1)Cd and Zn. The objective was to measure effects of Cd, Zn and nitrogen (N) status on the pools of metal-binding non-protein thiols: glutathione and phytochelatins, (gamma-glutamyl-cysteinyl)(n)-glycine (PC). In E. linza, ammonium pools were higher, but amino acid pools, total N and protein contents were lower than in E. prolifera. Reduced glutathione (GSH) pools were positively correlated with free glutamate and protein contents. In E. linza GSH pools increased and the ratio of reduced to oxidized glutathione (GSH:(GSH+0.5GSSG)), an indicator of oxidative stress, decreased with Cd contents, indicating Cd-induced glutathione oxidation. Total glutathione pools (reduced plus oxidized) ranged from 16nmolSgdwt(-1) in controls (at 0.5micromolCdgdwt(-1)) to 179nmolSgdwt(-1) (at 1.9micromolCdgdwt(-1)) at the highest cadmium dosage. Cadmium stimulated PC synthesis in E. prolifera which suggests that in N-rich algae, glutathione pools were high enough for PC synthesis. In both species GSH and protein increased with Zn contents, whereas GSH:(GSH+0.5GSSG) decreased, which would indicate Zn-induced oxidative stress; in E. linza, at the highest salinity the glutathione redox ratio decreased from 0.61 (at 2.9micromolZngdwt(-1)) to 0.26 (at 4.9nmolSgdwt(-1)) (at 0.5molCdgdwt(-1)). PCs were not synthesized in response to Zn, which may have resulted in Zn-induced GSH oxidation. The presence of both oxidative effects (Cd, Zn) and detoxification (Cd) could be identified by observing the responses of glutathione and PC pools to metal stress.     

香港西贡滨珊瑚REE的地球化学特征及其与海平面变化的关系

用ICP-MS技术测定了位于珠江口西岸香港西贡滨珊瑚在1991～2002年(分辨率达到0.5a)的稀土元素(REE)含量。实验结果显示香港滨珊瑚REE具有Ce负异常、重稀土富集这种典型的海水相分布模式。香港滨珊瑚中REE含量处于目前已见报道中的高值范围,与巴布亚新几内亚珊瑚的REE含量相当。通过与不同地区的比较,香港珊瑚高REE含量很可能就是毗邻的珠江水体高REE的直接反映,而且同南海北缘半封闭边缘海的性质有关。香港珊瑚REE的来源主要为珠江口及其相邻的陆缘沉积物。此外,1991～2002年香港珊瑚REE含量年际下降趋势十分明显,Ce负异常和重稀土富集的程度也呈加剧的趋势,分布模式向海水相转化。REE含量与海平面的年际变化之间有显著的负相关关系(r=-0.7～-0.9),而且重稀土与海平面的相关系数优于轻稀土。上述结果揭示了热带滨珊瑚对近期全球变暖、极冰融化和海水膨胀所引起的海平面快速上升的响应。     

A New Emission Mode of PSR B1859+07

Previous studies have identified two emission modes in PSR B1859+07: a normal mode that has three prominent components in the average profile, with the trailing one being the brightest, and an anomalous mode(i.e., the A mode) where emissions seem to be shifted to an earlier phase. Within the normal mode, further analysis has revealed the presence of two submodes, i.e., the cW mode and c B mode, where the central component can appear either weak or bright. As for the anomalous mode, a new bright ...     

Effect of Matching Algorithm and Profile Shape on Pulsar Pulse Time of Arrival Uncertainties

For high-precision pulsar timing analysis and low-frequency gravitational wave detection, it is essential to accurately determine pulsar pulse times of arrival(ToAs) and associated uncertainties. To measure the ToAs and their uncertainties, various cross-correlation-based techniques can be employed. We develop methodologies to investigate the impact of the template-matching method, profile shape, signal-to-noise ratio of both template and observation on ToA uncertainties. These methodologies are...     

Effect of Dietary Phosphorus on the Growth and Body Components of Juvenile Synechogobius hasta

The effect of dietary phosphorus on the growth and body components of juvenile Synechogobius hasta was determined. Different percentages of dietary phosphorus (0.63, 0.77, 0.93, 1.06, 1.22 and 1.36) were tested by feeding the fish (body weight, 15.81 g ± 0.32 g; 20 individuals each group; 3 groups each percentage) at a surplus of 5%–10% above satiation for 35 d. Dietary phosphorus did not significantly affect the specific growth rate, feed intake, feed conversion ratio and protein efficiency rate. Nitrogen ...     

Detection of the end point temperature of thermal denatured protein in fish and chicken meat through SDS-PAGE electrophoresis

Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was applied in the detection of the end point temperature (EPT) of thermal denatured protein in fish and meat in this study. It was also used in studying the thermal denatured temperature range of proteins in salmon and chicken meat. The results show that the temperature ranges of denatured proteins were from 65 ℃ to 75 ℃ , and these temperature ranges were influenced by the processing methods. Through SDS-PAGE, the features of repeated he...     

The Effect of Temperature on Growth and Energy Budget of the Polychaete,Neanthes japonica Izuka

Growth and energy budget of the polychaete, Neanthesjaponica, at various temperatures (17, 20, 23, 26 and 29 ℃) were investigated in this study. The growth, as indicated by final dry weight and specific growth rate (SGR), increased with increasing temperature, with the maximum level at 26℃, and then decreased significantly at 29℃. A similar trend was observed in feeding rate, food conversion efficiency (FCE) and apparent digestive rate (ADR). However, no significant differences were detected in ADR among all the temperature treatments. In the pattern of energy allocation, faeces energy was only a small component of energy budget and had little influence on the proportion of food energy allocated to growth. The metabolic energy accounted for a large portion of energy intake for each temperature treatment. The nitrogen excretion was appreciable with changing temperature. The two expendi-ture terms (respiration energy and excretion energy) in energy budget were the major factors influencing the proportion of food en-ergy allocated to growth. These results revealed that temperature affected the growth of N. japonica mainly by influencing feeding rate and FCE. In addition, regression equations describing the relationship between feeding rate, faecal production, SGR, FCE and temperature were obtained. The optimum temperatures for feeding rate, FCE and SGR were estimated at 25.01 ℃, 24.24℃ and 24.73 ℃, respectively, from the regression equations.