Objective Intro Materials Procedure Results 1 Results 2 Results 3 Discussion Lit. Cited Prep Sheet



Treatment 1: preliminary assay for effective range of arsenic concentrations
Embryos were divided into two groups, 8h and 12h, which corresponded to the age at which they would be first exposed to arsenic in the form of sodium arsenate dibasic heptahydrate. The 8h group, staged at 70% to 100% epiboly, was subjected to five concentrations of sodium arsenate in zebrafish embryo medium, 25 uM, 50 uM, 100 uM, 200 uM, and 400 uM, respectively. The 12h group was subjected to the same concentrations at approximately the 2-6 somite stage. At 24 post-fertilization, embryos were staged at 31 hpf. Of 120 embryos, two inviable embryos appeared to be arrested early in development and one embryo was viable but deformed, lacking the posterior region. Embryos were reexamined at 48h after fertilization and both groups were staged at 60-72 hpf and all appeared healthy (Figure 1).



Figure 1. Zebrafish embryos observed during the preliminary concentration assay. (A) was viewed at 24 hours after fertilization and was staged at 31 hpf. (B) was viewed at 48 hours after fertilization and was staged at 60 hpf. Isolated malformations were also viewed 24 hours after fertilization, including potentially underformed embryos at 400 µM (C) and one embryo lacking a posterior at 50 µM (D).


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