Lethal and Sub-Lethal Effects and Modulation of Gene Expression Induced by T Kinase Inhibitors in Zebrafish (Danio Rerio) Embryos

Tyrosine kinase inhibitors (TKIs) are designed for targeted cancer therapy. The consumption of these drugs during the last 20 years has been constantly rising. In the zebrafish (Danio rerio) embryo toxicity test, we assessed the toxicity of six TKIs: imatinib mesylate, erlotinib, nilotinib, dasatinib, sorafenib and regorafenib. Imatinib mesylate and dasatinib induced lethal effects, while regorafenib, sorfenib and dasatinib caused a significant increase of sub-lethal effects, predominantly oedema, no blood circulation and formation of blood aggregates. The analyses of the changes in the expression of selected genes associated with the hormone system after the exposure to imatinib mesylate, dasatinib and regorafenib demonstrated that all three tested TKIs deregulated the expression of oestrogen receptor esr1, cytochrome P450 aromatase (cypa19b) and hydroxysteroid-dehydrogenase (hsd3b), regorafenib, and also thyroglobulin (tg). The expression of genes involved in the DNA damage response (gadd45 and mcm6) and apoptosis (bcl2) was deregulated only by exposure to regorafenib. The data indicate that common mechanisms, namely antiangiogenic activity and interference with steroidogenesis are involved in the TKI induced sub-lethal effects and potential hormone disrupting activity, respectively. The residues of TKIs may represent an environmental hazard; therefore, further ecotoxicological studies focusing also on the effects of their mixtures are warranted.

Effect of Diuron on Embryo-Larval Development of Javanese Medaka (Oryzias javanicus, Bleeker 1854)

Some herbicides exert hormetic or biphasic non-monotonic dose-response (NMDR), which is one of the major challenges for ecological risk assessment (ERA) of pesticides pollution. In this study, fish embryo toxicity test (FET) with Javanese medaka (Oryzias javanicus) to sublethal concentration of diuron was determined. Inverted U-shape heart rate was observed at 3 days post-exposure (dpe) and 7 dpe. However, at 13 dpe the heart rate (104 ± 2.90 heartbeat/min.) decreased in 10.00 mg.L-1 exposed-embryos. At 20 dpe, hatchability and survival rate were reduced in 5.00 mg.L-1 and 10.00 mg.L-1 exposed groups. Hormetic developmental deformities were observed in embryo-larvae of Javanese medaka. The results revealed a biphasic effect of low concentrations of diuron on some morphological and physiological features of Javanese medaka embryo-larvae, which might be attributed to endocrine disruption of this herbicide. Further studies to support these effects were recommended.

Green Synthesis of CuO Nanoparticles and its Application on Toxicology Evaluation

This study aims to understand the major effects of Copper oxide nanoparticles on toxic and fish pathogens by using a green method. Safer methods like the usage of microorganisms prove to be eco-friendly and extremely practical than the regular physical and chemical methods. The characters and features of the CuO particles were understood by using analytical techniques like XRD, UV-vis spectroscopy, FTIR, SEM-EDX, TEM and AFM. Further analysis showed that the spherical particle size was around 100 nm. When prepared in pure water to zebrafish, with a 96 h LC50 concentration of 67.61 mg/L. The possibility to evaluate hatching time in the 96h acute embryo toxicity test seems to be an advantage against that of the 96-hour toxicity since this toxicity was a life stage-dependent.

Toxicological Evaluation of SiO2 Nanoparticles by Zebrafish Embryo Toxicity Test

As the use of nanoparticles (NPs) is increasing, the potential toxicity and behavior of NPs in living systems need to be better understood. Our goal was to evaluate the developmental toxicity and bio-distribution of two different sizes of fluorescently-labeled SiO2 NPs, 25 and 115 nm, with neutral surface charge or with different surface functionalization, rendering them positively or negatively charged, in order to predict the effect of NPs in humans. We performed a zebrafish embryo toxicity test (ZFET) by exposing the embryos to SiO2 NPs starting from six hours post fertilization (hpf). Survival rate, hatching time, and gross morphological changes were assessed at 12, 24, 36, 48, 60, and 72 hpf. We evaluated the effect of NPs on angiogenesis by counting the number of sub-intestinal vessels between the second and seventh intersegmental vessels and gene expression analysis of vascular endothelial growth factor (VEGF) and VEGF receptors at 72 hpf. SiO2 NPs did not show any adverse effects on survival rate, hatching time, gross morphology, or physiological angiogenesis. We found that SiO2 NPs were trapped by the chorion up until to the hatching stage. After chemical removal of the chorion (dechorionation), positively surface-charged SiO2 NPs (25 nm) significantly reduced the survival rate of the fish compared to the control group. These results indicate that zebrafish chorion acts as a physical barrier against SiO2 NPs, and removing the chorions in ZFET might be necessary for evaluation of toxicity of NPs.