![]() ![]() The internal standard was 115In for both calibration curve and sample analysis. Calibration curves for determining REEs ranged from 0.5 to 1,000 µg/L for Normal and from 0.005 to 10 µg/L for High Sensitivity and were constructed daily by analysis of standard solutions prepared immediately before analysis. The analysis was performed in High Sensitivity mode. All samples analyzed in ICP-MS were prepared in HNO 3 solution (2% v/v). Nitric acid (HNO 3, 69% v/v ppb-trace analysis grade) was purchased from Scharlau (Barcelona, Spain). ![]() A Milli-Q unit (Millipore, United States) was used to obtain high-purity water (resistivity = 18.2 MΩ cm) was obtained from a Milli-Q unit (Millipore, United States). This observation was carried out after immobilizing larvae and embryos by adding a 10 −4 M chromium sulfate, which allowed screening of bottom-laying embryos/larvae in an inverted microscope, ×10 magnification.Īnalytical concentrations of Ce and La in the samples were determined by inductively coupled plasma mass spectrometry (ICP-MS, Aurora M90 Bruker, Germany). Subsequent observation of offspring was performed 3 days post-fertilization allowing detection of % prepared immediately before analysis developmental defects (DD) as larval malformations or pre-larval arrest and of mortality. FR was measured starting from the appearance of fertilization membrane and of early cleavage (2-cell stage) for approximately 3 h post-fertilization. These duplicate sperm suspensions, in turn, fertilized eggs from three females, thus providing six-replicate embryo cultures that were observed for fertilization rate (FR, % fertilized eggs) and then for offspring quality. Sperm suspension was carried out by 1% dilution of “dry” sperm (as released by testes from two males) in agent solutions at concentrations ranging from 10 −8 to 10 −5 M. A preliminary assay tested a duration of control sperm suspension (10 to 60 min), allowing to either assess inhibition or stimulation of fertilization rate, leading to an intermediate (∼50%) fertilization rate, and was found as 30-min sperm exposure (Pagano et al. < 10 −6 M.Ĭerium nitrate, lanthanum nitrate and their equimolar combinations were tested for their effects on Sphaerechinus granularis sea urchin sperm in changing fertilization success and the frequency of developmental defects in the offspring of exposed sperm. The results confirmed a shift from inhibition to stimulation of tested events by comparing 10 −5 M vs. Within the frame of REE-associated hormetic effects, the present study was aimed at verifying the effects of micromolar and sub-micromolar levels of two REEs, Ce and La, and their combination on sea urchin sperm fertilization success and offspring embryogenesis. 2022 Schirrmacher, 2021 Shibamoto and Nakamura, 2018). The multiple implications of hormesis have been reported in an extensive body of basic and applied disciplines (e.g. This duplicity of REE-associated effects is not specific for REEs, but may be ascribed to a general phenomenon of a concentration-related shift from inhibition, or “toxicity” for high agent concentrations to stimulation for lower agent concentrations, also termed hormesis, and previously tagged as “Arndt-Schulz effect” (Stebbing 1982 Pagano et al. 2017).Īpart from their adverse effects, REEs also display recognized stimulatory effects, as reported in a body of literature on their use as components of fertilizers improving crop yields and in livestock feed additives (Abdelnour et al. REE-associated adverse effects have been assessed in a vast body of literature encompassing several biota, with implications also in human health, so that REEs have raised extensive health concern and are viewed as emergent contaminants (Brouziotis et al. ![]() Rare earth elements (REEs) include a group of elements, the lanthanoids and two closely related elements, yttrium (Y) and scandium (Sc) which are recognized to be indispensable in the present world, due to their extensive roles in a number of technologies (Du and Graedel 2013 Pagano et al. ![]()
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