Oxamyl exerts developmental toxic effects in zebrafish by disrupting the mitochondrial electron transport chain and modulating PI3K/Akt and p38 Mapk signaling

Parental exposure to Cypermethrin causes intergenerational toxicity in zebrafish offspring

Cypermethrin (CYP), a synthetic pyrethroid pesticide, has been detected in agriculture and aquaculture. However, there is limited knowledge about the transgenerational impacts. This study aimed to investigate the developmental toxicity of CYP on F1 larvae offspring of adult zebrafish exposed to various CYP concentrations (5, 10, and 20 μg/L) for 28 days. The results indicated that CYP accumulated in parental zebrafish, and CYP was below the limit of quantification in offspring. Paternal exposure impacted the hatching rate and heart rate of the F1 generation. Furthermore, CYP significantly impacted the development of swim bladders in progeny and dysregulated the genes relevant to swim bladder development. The neutrophil migrated to the swim bladder. The mRNA levels of the inflammatory factors were also significantly elevated. According to network toxicology, PI3-AKT may be the signaling pathway for CYP-influenced bladder development. Subsequent molecular docking and Western blot analysis showed CYP affected the PI3-AKT signaling pathway. Notably, MK-2206, a specific Akt inhibitor, rescued the CYP-induced damage of swim bladder development in offspring. The present study highlights the potential risks of CYP on the development of offspring and lasting impact in aquatic environments.

High-Resolution Respirometry for the Assessment of Teratogenic Chemicals

Pesticides are often used in agriculture and residential areas to mitigate pests and weeds. These chemicals can enter aquatic ecosystems via runoff and rain events, exerting negative effects on aquatic species. In rapidly developing fish embryos, metabolic disruption can alter the developmental trajectory and alter ATP levels. Therefore, it is important to quantify mitochondrial integrity in organisms following exposure to pesticides. To achieve this, a high throughput method to assess pesticide effects on oxidative phosphorylation and mitochondria has been optimized for fish embryos. Fish embryos are first exposed to pesticides for 24 or 48 h, and oxygen consumption rates are measured using the Seahorse XFe24/96 Flux Analyzer (formerly Seahorse Biosciences, now Agilent). The assay utilizes a single embryo and precisely measures oxygen consumption and extracellular acidification. Based upon these measurements, characteristics related to mitochondrial bioenergetics are calculated to provide information on mitochondrial integrity. Using this approach, one can identify pesticides affecting the electron transport chain and ultimately ATP production. In this chapter, we describe the mitochondrial stress test to understand mitochondrial dysfunction and metabolic shifts within the fish embryo.

Mevinphos induces developmental defects via inflammation, apoptosis, and altered MAPK and Akt signaling pathways in zebrafish

Mevinphos, an organophosphate insecticide, is widely used to control pests and enhance crop yield. Because of its high solubility, it can easily flow into water and threaten the aquatic environment, and it is known to be hazardous to non-target organisms. However, little is known about its developmental toxicity and the underlying toxic mechanisms. In this study, we utilized zebrafish, which is frequently used for toxicological research to estimate the toxicity in other aquatic organisms or vertebrates including humans, to elucidate the developmental defects induced by mevinphos. Here, we observed that mevinphos induced various phenotypical abnormalities, such as diminished eyes and head sizes, shortened body length, loss of swim bladder, and increased pericardiac edema. Also, exposure to mevinphos triggered inflammation, apoptosis, and DNA fragmentation in zebrafish larvae. In addition, MAPK and Akt signaling pathways, which control apoptosis, inflammation, and proper development of various organs, were also altered by the treatment of mevinphos. Furthermore, these factors induced various organ defects which were confirmed by various transgenic models. We identified neuronal toxicity through transgenic olig2:dsRed zebrafish, cardiovascular toxicity through transgenic fli1:eGFP zebrafish, and hepatotoxicity and pancreatic toxicity through transgenic lfabp:dsRed;elastase:GFP zebrafish. Overall, our results elucidated the developmental toxicities of mevinphos in zebrafish and provided the parameters for the assessment of toxicities in aquatic environments.

Developmental toxicity of flufenacet including vascular, liver, and pancreas defects is mediated by apoptosis and alters the Mapk and PI3K/Akt signal transduction in zebrafish

Release of agrochemicals from agricultural fields could unintentionally harm organisms that not targeted by pesticides. Flufenacet is one of the oxyacetamide herbicide applied in cultivation fields of crops and this has a possibility of unintentional exposure to diverse ecosystems including streams and surface water. Despite these environmental risks, limited information regarding toxicity of flufenacet on vertebrates is available. This study is aimed to assess environmental hazards and underlying toxic mechanisms of flufenacet by using a zebrafish model. Mortality measurements and morphological observations after the treatment of flufenacet suggested developmental toxicity of flufenacet in zebrafish. In addition, its toxicity on specific organs was evaluated using transgenic fluorescent zebrafish embryo. Adverse effects of flufenacet on vascular and hepatopancreatic development were demonstrated using Tg(flk1:EGFP) and Tg(fabp10a:DsRed; ela3l:EGFP) respectively. To address intracellular actions of flufenacet in zebrafish, cellular responses including apoptosis, cell cycle modulation, and Mapk and Akt signaling pathway were verified in transcriptional and protein levels. These results demonstrated developmental toxicity of flufenacet using the zebrafish model, providing essential information for assessing its potential hazards on vertebrates that are not directly targeted by the pesticide and for elucidating molecular mechanisms.