title: Effects of Ca2+ or Na+ on metallothionein expression in tilapia larvae (Oreochromis mossambicus) exposed to cadmium or copper.
abstract: The objectives of this study were to try to determine the reasons of the external Ca(2+) and Na(+) enhancement of Cd(2+) and Cu(2+) resistance in fish. Tilapia larvae at 3 days posthatch were exposed to (A) 0 (control), 40 microg/L Cd(2+), 40 microg/L Cd(2+) + 2 mM Ca(2+) (Cd/hyper-Ca), and 2 mM Ca(2+) or (B) 0 (control), 75 microg/L Cu(2+), 75 microg/L Cu(2+) + 0.52 mM Na(+) (Cu/hyper-Na), and 0.52 mM Na(+). After 48 hours, results indicated that (1) Cd/hyper-Ca and Cu/hyper-Na treatments showed decreased growth inhibition induced by the metals; (2) metal accumulation in Cd/hyper-Ca-treated larvae was lower compared with those exposed only to Cd; and (3) metallothionein (MT) expression was significantly higher in Cu/hyper-Na-treated larvae than in the group treated with Cu only. Taking all of this into account, either supplementary Ca(2+) or Na(+) in ambient water may help fish to maintain Ca(2+) or Na(+) homeostasis, which could decrease metal accumulation and its detrimental effects. Consequently, the fish increase MT expression and retard the growth inhibition caused by metals.
authors.affiliation: Department of Aquatic Biosciences, National Chiayi University, 300 University Road, Chiayi 600, Taiwan. sumei@mail.ncyu.edu.tw
authors.forename: S M
authors.initials: SM
authors.lastname: Wu
authors.forename: Y-C
authors.initials: YC
authors.lastname: Ho
authors.forename: M J
authors.initials: MJ
authors.lastname: Shih
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D002118:Calcium / Q000378:metabolism*; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000187:drug effects*; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D008668:Metallothionein / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D013624:Taiwan; D017210:Tilapia
chemical_list: D002104:Cadmium; D003300:Copper; D008668:Metallothionein; D009584:Nitrogen; D002118:Calcium