Effects of cartap on the early-life stages of medaka (Oryzias latipes)

Transgenic fluorescent zebrafish Tg(fli1:EGFP)y¹ for the identification of vasotoxicity within the zFET

The fish embryo toxicity test (FET) is currently one of the most advocated animal alternative tests in ecotoxicology. To date, the application of the FET with zebrafish (zFET) has focused on acute toxicity assessment, where only lethal morphological effects are accounted for. An application of the zFET beyond acute toxicity, however, necessitates the establishment of more refined and quantifiable toxicological endpoints. A valuable tool in this context is the use of gene expression-dependent fluorescent markers that can even be measured in vivo. We investigated the application of embryos of Tg(fli1:EGFP)(y1) for the identification of vasotoxic substances within the zFET. Tg(fli1:EGFP)(y1) fish express enhanced GFP in the entire vasculature under the control of the fli1 promoter, and thus enable the visualization of vascular defects in live zebrafish embryos. We assessed the fli1 driven EGFP-expression in the intersegmental blood vessels (ISVs) qualitatively and quantitatively, and found an exposure concentration related increase in vascular damage for chemicals like triclosan, cartap and genistein. The fluorescence endpoint ISV-length allowed an earlier and more sensitive detection of vasotoxins than the bright field assessment method. In combination with the standard bright field morphological effect assessment, an increase in significance and value of the zFET for a mechanism-specific toxicity evaluation was achieved. This study highlights the benefits of using transgenic zebrafish as convenient tools for identifying toxicity in vivo and to increase sensitivity and specificity of the zFET.

Highly sensitive turn-on fluorescent detection of cartap via a nonconjugated gold nanoparticle–quantum dot pair mediated by inner filter effect

The well-dispersed AuNPs exhibited a tendency to aggregate when exposed to cartap with positively charged amine groups, which induced an absorption band transition from 522 nm to the long-wavelength band, and restored the IFE-decreased emission of CdTe QDs for cartap detection.

Aquatic toxicity of cartap and cypermethrin to different life stages of Daphnia magna and Oryzias latipes

Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S'-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 microg/L and 0.00061 microg/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 microg/L and cypermethrin up to 1.9 microg/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults, which may be partly due to the protective role of the chorion. The incidence of larval fish deformity was significantly higher after a 96 hr exposure to as low as 250 microg/L of cartap or 40 microg/L of cypermethrin. The mixture of both compounds showed no synergistic toxicity. The extremely high acute-to-chronic ratio suggests that the standard acute lethal toxicity assessment might not reflect the true environmental hazards of these frequently used pesticides. Ecological hazard assessments of long-term low dose or pulsed exposures to cartap and cypermethrin may reveal more realistic consequences of these compounds in surface water.