Does subcellular distribution in plants dictate the trophic bioavailability of cadmium to Porcellio dilatatus (crustacea, isopoda)?

Abstract

The present study examined how subcellular partitioning of Cd in plants with different strategies to store and detoxify Cd may affect trophic transfer of Cd to the isopod Porcellio dilatatus. The plant species used were Lactuca sativa, a horticultural metal accumulator species; Thlaspi caerulescens, a herbaceous hyperaccumulator species; and the nonaccumulator, T. arvense. Taking into account that differences in subcellular distribution of Cd in plants might have an important role in the bioavailability of Cd to a consumer, a differential centrifugation technique was adopted to separate plant leaf tissues into four different fractions: cell debris, organelles, heat-denatured proteins, and heat-stable proteins (metallothionein-like proteins). Plants were grown in replicate hydroponic systems and were exposed for 7 d to 100 microM Cd spiked with 109Cd. After a 14-d feeding trial, net assimilation of Cd in isopods following consumption of T. caerulescens and T. arvense leaves reached 16.0 +/- 2.33 and 21.9 +/- 1.94 microg/g animal, respectively. Cadmium assimilation efficiencies were significantly lower in isopods fed T. caerulescens (10.0 +/- 0.92%) than in those fed T. arvense (15.0 +/- 1.03%). In further experiments, Cd assimilation efficiencies were determined among isopods provided with purified subcellular fractions of the three plants. On the basis of our results, Cd bound to heat-stable proteins was the least bioavailable to isopods (14.4-19.6%), while Cd bound to heat-denatured proteins was the most trophically available to isopods (34.4-52.8%). Assimilation efficiencies were comparable in isopods fed purified subcellular fractions from different plants, further indicating the importance of subcellular Cd distribution in the assimilation. These results point to the ecological relevance of the subcellular Cd distribution in plants, which directly influence the trophic transfer of Cd to the animal consumer.

Blood δ-ALAD, lead and cadmium concentrations in spur-thighed tortoises (Testudo graeca) from Southeastern Spain and Northern Africa

“…Cadmium can also decrease the thyroid hormone triodothyronine: thyroxine ratios in fence lizards (Scelooporus undulatus, Brasfield et al 2004), and induction of metal-binding proteins may be an adaptive response of turtles (Chrysemys picta) to Cd exposure (Rie et al 2001). Cd is particularly dangerous because plants growing in contaminated soils can absorb and accumulate Cd in edible tissues in large quantities without any visible signs, thereby introducing the metal into the food (Monteiro et al 2008(Monteiro et al , 2009. Some plant The line describing the relationship as determined by linear regression (and associated 95% confidence limits).…”

Investigations of responses to metal pollution in land snail populations (Cantareus aspersus and Cepaea nemoralis) from a smelter-impacted area

“…Actually, uptake and elimination rate constants could also be influenced by TM levels and sequestration in vegetation because trophic transfer could be affected by bioavailability of TMs in the diet (Vijver et al 2004). As levels and sequestration of TM in plants vary according to species and exposure to metals (Clemens 2006), and because TM trophic availability for consumers is affected by metal storage form in foodstuffs (Monteiro et al 2008;Vijver et al 2004), bioavailability of TM to snails may vary among sites because of the characteristics of the vegetation available. Thus, these parameters should be considered for an accurate assessment of bioavailability of TM in food webs involving snails.…”

Effects on survival and reproduction of Porcellio dilatatus exposed to different Cd species

“…A mixture of lettuce (Lactuca sativa) leaves and gelatine was selected as a suitable food substrate to be used as the exposure route (Mann et al 2005;Monteiro et al 2008). Non-contaminated L. sativa leaves were reduced to powder using a mortar and pestle, and were mixed with a gelatine solution prepared from 2.5 g gelatine powder (VWR Prolabo, Fontenay Sous Bois, France) to which 12.5 ml deionised water (Milli-Q Ò ) was added, and then mixed by vortexing (Wallace and Lopez 1996).…”