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See detailToxicokinetics of selenium in the slider turtle Trachemys scripta
Dyc, Christelle; Far, Johann ULg; Gandar, Frederic ULg et al

in Ecotoxicology (2016), 25

Selenium (Se) is an essential element that can be harmful for wildlife. However, its toxicity in poikilothermic amniotes, including turtles, remains poorly investigated. The present study aims at ... [more ▼]

Selenium (Se) is an essential element that can be harmful for wildlife. However, its toxicity in poikilothermic amniotes, including turtles, remains poorly investigated. The present study aims at identifying selenium toxicokinetics and toxicity in juvenile slider turtles (age: 7 months), Trachemys scripta, dietary exposed to selenium, as selenomethionine SeMet, for eight weeks. Non-destructive tissues (i.e. carapace, scutes, skin and blood) were further tested for their suitability to predict selenium levels in target tissues (i.e. kidney, liver and muscle) From conservation perspective. 130 juvenile yellow-bellied slider turtles were assigned in three groups of 42 individuals each (i.e. control, SeMet1 and SeMet2). These groups were subjected to a feeding trial including an eight-week supplementation period SP8 and a following four-week elimination period EP4. During the SP8, turtles fed on diet containing 1.1 ± 0.04, 22.1 ± 1.0 and 45.0 ± 2.0 µg.g-1 of selenium (control, SeMet1 and SeMet2, respectively). During the EP4, turtles fed on non-supplemented diet. At different time during the trial, six individuals per group were sacrificed and tissues collected (i.e. carapace, scutes, skin, blood, liver, kidney, muscle) for analyses. During the SP8 (Figure 1), both SeMet1 and SeMet2 turtles efficiently accumulated selenium from a SeMet dietary source. The more selenium was concentrated in the food, the more it was in the turtle body but the less it was removed from their tissues. Moreover, SeMet was found to be the more abundant selenium species in turtles’ tissues. Body condition (i.e. growth in mass and size, feeding behaviour and activity) and survival of the SeMet1 and SeMet2 turtles seemed to be unaffected by the selenium exposure. There were clear evidences that reptilian species are differently affected by and sensitive to selenium exposure but the lack of any adverse effects was quite unexpected. [less ▲]

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See detailToxicokinetics of selenium in Chelonians: trophic exposure in Trachemys scripta scripta
Dyc, Christelle ULg; Greco, Anaïs; Das, Krishna ULg

(2011, December)

Background. Se is primordial for all development stages in oviparous species but can induce cellular damages (e.g. oxidative stress, histopathotoxicity) , embryo- and immunotoxicity (Usdi 1998; Hoffman ... [more ▼]

Background. Se is primordial for all development stages in oviparous species but can induce cellular damages (e.g. oxidative stress, histopathotoxicity) , embryo- and immunotoxicity (Usdi 1998; Hoffman 2002) , even at low concentration. Unlike birds and fishes, little is currently known on Se toxicology in reptiles, such as turtles. Most studies reported tissue burdens from field-captured or death animals but rarely provided an understanding of the dose, duration or pathway of exposure. Our present study aims to investigate toxicokinetic of Se through an in vivo and per os exposure of the yellow-bellied slider turtle Trachemys scripta scripta. Furthermore relationship between Se concentration in internal tissues (liver, kidney, muscle ) and external tissues (carapace, skin, blood) will evaluate usefulness of these last in the framework of non-invasive sampling in protected turtle species. Methodology. 160 yellow-bellied slider turtles, around four weeks old, were acquired in September 2010 and placed by pair in individual tank for a six-month acclimatization period. Lengths, as straight carapace length SCL, ranged from 1.7 to 6.4 cm. Three groups of 42 individuals each were designed. The feeding trial consisted in an eight-week supplementation period followed by a four-week depuration period. At some intervals during that time scale, six individuals per group were sacrificed and tissues were collected (carapace, scutes, skin, blood, liver, kidney, muscle) for selenium analysis. During the supplementation period, turtles were fed with diet containing 0 (control) , 23 or 47 µg.g-1 of selenium as seleno-L-methionine. During the depuration period, the remaining individuals were fed with non-supplemented control diet. Total selenium was investigated by ICPMS. Results and discussion. The Se-concentration in all collected tissues increased in a dose-dependent way over the course of the supplementation period. Se accumulation had no effect on survival, diet behavior or growth. Higher Se levels were observed in kidney, followed by muscle and blood. During the recovery period, Se levels decreased in tissues in a significantway except in blood, muscle and carapace. Blood, skin and carapace Se levels were positively correlated to those in kidney and muscle. Such relationships were also observed between liver and carapace, and blood. Results suggested a Se transfer through the food intake and the potential use of carapace and skin as relevant tools in non-invasive biomonitoring studies. [less ▲]

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