The ‘europium anomaly’ in plants: facts and fiction

Plant and Soil - Rare earth elements (REEs) and normalized REE patterns determined in plant and soil samples represent powerful tools to trace biogeochemical processes during weathering, soil...     

Lead toxicity at different life stages of the giant prawn (Macrobrachium rosenbergii,de Man): considerations of osmoregulatory capacity and histological changes in adult gills

This study evaluated the acute toxicity of lead in different life stages of the freshwater prawn Macrobrachium rosenbergii, determined the effect of sublethal Pb concentrations on osmoregulatory capacity (OC), measured the Pb level in gills, and investigated the effect of Pb on the structure of the gills of adult prawns. The 24-, 48-, and 96-h LC₅₀ values for Pb to M. rosenbergii increased progressively with increasing life stage, from post-larvae (PL), juvenile to adult. The 24- and 48-h LC₅₀ values for post-larvae ranged from 0.01- to 0.09-mg Pb/L. The 24-, 48-, and 96-h LC₅₀ values for Pb were lower at 12 ppt than those at 0 ppt for either the juveniles or the adults. At 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.47-, 0.58-, and 2.03-mg Pb/L, respectively. Meanwhile, at 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.63-, 4.44-, and 7.98-mg Pb/L, respectively. In adults, the OC values of controls and prawns exposed to 2- and 4-mg Pb/L at 0 ppt were not significantly different. The OC of prawns exposed to and 2-mg Pb/L at 12 ppt increased by 72 and 109% from the OC of the control prawns. At media 12 ppt, the OC value of prawns exposed to 1-mg Pb/L was significantly different from that of prawns exposed to 2-mg Pb/L. The concentrations of Pb in gill tissues increased significantly in Pb exposed prawns both at 0 and 12 ppt. The level of Pb in gills of prawns exposed to 2-mg Pb/L at 12 ppt was not significantly different from those exposed at 0 ppt. The severe toxic actions of Pb were noted in gills of prawns exposed in media 12 ppt. Hyperplasia and necrosis were observed in gill lamellae, resulting in abnormal gill tips after Pb exposure at media 12 ppt. Since the effect of Pb is more pronounced in higher salinity (12 ppt) than in freshwater (0 ppt) it is clear that aquaculture of M. rosenbergii should be conducted in freshwater ponds.     

Studies on the salinity and desiccation tolerances of Helice tridens and Helice japonica (Decapoda: Grapsidae)

In the Shigenobu River Estuary (33 ° 48′ 18″ N, 132 ° 41′ 10″ E), Matsuyama (Japan), Helice tridens inhabits the mid-intertidal zone to the limit of the high tide, while H. japonica is found around the mid-intertidal zone. In addition, H. japonica is distributed further downstream than H. tridens. These differences suggest that H. japonica has a lower salinity and desiccation tolerance than H. tridens. Laboratory experiments on salinity tolerance confirmed the higher tolerance of H. tridens compared to H. japonica. Helice tridens survived at least a week under fresh water conditions, whereas most of the H. japonica died. Helice tridens was shown to be more able to tolerate desiccation than H. japonica, through behavioral, not physiological, adaptation to dry conditions. The present results demonstrate a stronger adaptation of H. tridens to semi-terrestrial and/or freshwater environments than H. japonica. This revised version was published online in July 2006 with corrections to the Cover Date.     

Apoplastic water fraction and rehydration techniques introduce significant errors in measurements of relative water content and osmotic potential in plant leaves

Relative water content (RWC) and the osmotic potential (π) of plant leaves are important plant traits that can be used to assess drought tolerance or adaptation of plants. We estimated the magnitude of errors that are introduced by dilution of π from apoplastic water in osmometry methods and the errors that occur during rehydration of leaves for RWC and π in 14 different plant species from trees, grasses and herbs. Our data indicate that rehydration technique and length of rehydration can introduce significant errors in both RWC and π. Leaves from all species were fully turgid after 1–3 h of rehydration and increasing the rehydration time resulted in a significant underprediction of RWC. Standing rehydration via the petiole introduced the least errors while rehydration via floating disks and submerging leaves for rehydration led to a greater underprediction of RWC. The same effect was also observed for π. The π values following standing rehydration could be corrected by applying a dilution factor from apoplastic water dilution using an osmometric method but not by using apoplastic water fraction (AWF) from pressure volume (PV) curves. The apoplastic water dilution error was between 5 and 18%, while the two other rehydration methods introduced much greater errors. We recommend the use of the standing rehydration method because (1) the correct rehydration time can be evaluated by measuring water potential, (2) overhydration effects were smallest, and (3) π can be accurately corrected by using osmometric methods to estimate apoplastic water dilution.     

Effect of cadmium on survival,osmoregulation and gill structure of the Sunda prawn,Macrobrachium sintangense (de Man), at different salinities

The prawn Macrobrachium sintangense is likely to be subjected to occasional exposure to combined metal and saline stressors in its natural environment. This research evaluated the acute toxicity (96?h LC₅₀) of cadmium (Cd) on the prawn M. sintangense, with respect to the osmoregulatory capacity (OC) of prawns and to document histological changes in the gills after exposure to sublethal Cd concentrations at different salinities. The 96?h LC₅₀ of Cd to M. sintangense decreased with increasing salinity. The 96?h LC₅₀ values were 89.12 (72.53–109.50), 681.26 (554.20–837.46) and 825.37 (676.99–1006.27) μg CdL^?1 at 0, 10 and 20 ppt, respectively. The OC of prawns exposed to 30?μg?CdL^?1 at 0 ppt and to 300?μg?CdL^?1 at10 ppt decreased significantly compared with that of control prawns exposed to 0 and 10 ppt respectively. Swelling, hyperplasia and necrosis of gill lamellae resulting in the loss of marginal canals were observed in the gills of prawns exposed to 30?μg?CdL^?1 at 0 ppt and to 300?μg?CdL^?1 at 10 ppt for 7?days.     

Polymer waveguide sensor for early diagnostic and wellness monitoring

This paper unveils a platform to develop a compact, simple, reusable and disposable, and cost effective hand-held urinalysis device for home-health-care and doctor's office uses. A polymeric optical waveguide and colorimetric absorption were used as an optical sensor and sensing mode, respectively. The results of the tests show that the device was able to deliver quantitative results with the detection limits better than 0.1g/L, 0.2g/L, 0.025 g/L, and 0.1g/L for glucose, creatinine, albumin and total protein, respectively. There are some superiorities of this device as compared to the dip-stick counterpart, that are, better sensitivity, ability to deliver quantitative results and reusability. The device is being further miniaturized to use a LED and photodiode as a light source and detector, respectively. It is believed the device has potential for early diagnostic and wellness monitoring tool.     

Concentrations of Lead,Cadmium, and Mercury in Halfbeaks (Hyporhampus affinis) from the East Java Coast,Indonesia and Human Health Hazard

The objectives of this study were to measure the levels of lead, cadmium, and mercury in the muscle tissues of halfbeaks (Hyporhampus affinis) captured at five stations along the East Java coast, Indonesia. This fish is one of the important species and consumed by local people as a cheap source of protein. We evaluated the hazard level posed by the metals in relation to the maximum residual limit for human consumption and to estimate the weekly intake and compare it with the provisional tolerable weekly intake (PTWI). The Pb, Cd, and Hg concentrations in fish at all stations ranged from 0.006 to 0.023 mg/kg, 0.007 to 0.024 mg/kg, and 0.047 to 0.055 mg/kg wet weight, respectively. All samples of halfbeaks collected from this area appear to be safe for human consumption because their metals’ levels are below the permissible limit for human consumption and the maximum weekly intakes are below the recommended values of PTWI.