The Genius of the Zebrafish Model: Insights on Development and Disease

Nitenpyram-Induced Cardiac Toxicity in Early Developmental Stages of Zebrafish

Nitenpyram is a new neonicotinoid insecticide primarily used for the control of piercing-sucking pests as well as fleas and lice on animals. It is widely used around the world, and the concentrations and detection rates in surface water and groundwater are increasing. Current research has shown that nitenpyram is toxic to honey bee, silkworms, and other organisms, but the toxicity to aquatic organisms and the mechanisms of its toxicity are still unclear. This study uses zebrafish as the research model to investigate the adverse effects of nitenpyram on the early embryonic development of zebrafish. The results show that nitenpyram induces developmental toxicity and cardiac toxicity in zebrafish. Zebrafish exhibited pericardial edema and an increased distance between the atria and ventricles. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression of heart development-related genes tbx2b, gata4, vmhc, myh6, and nkx2.5 was inhibited. Additionally, nitenpyram induced oxidative stress in zebrafish, significantly increasing the production and accumulation of ROS in the cardiac region. Acridine orange staining results revealed that nitenpyram induced apoptosis in the cardiac region of zebrafish, and qRT-PCR results showed activation of the endogenous apoptosis pathways. Therefore, it is speculated that nitenpyram-induced oxidative stress alters the expression of heart-related genes and triggers endogenous apoptosis in zebrafish cardiomyocytes, ultimately leading to abnormal cardiac development.

The Development and Application of Opto-Chemical Tools in the Zebrafish

The zebrafish is one of the most widely adopted animal models in both basic and translational research. This popularity of the zebrafish results from several advantages such as a high degree of similarity to the human genome, the ease of genetic and chemical perturbations, external fertilization with high fecundity, transparent and fast-developing embryos, and relatively low cost-effective maintenance. In particular, body translucency is a unique feature of zebrafish that is not adequately obtained with other vertebrate organisms. The animal's distinctive optical clarity and small size therefore make it a successful model for optical modulation and observation. Furthermore, the convenience of microinjection and high embryonic permeability readily allow for efficient delivery of large and small molecules into live animals. Finally, the numerous number of siblings obtained from a single pair of animals offers large replicates and improved statistical analysis of the results. In this review, we describe the development of opto-chemical tools based on various strategies that control biological activities with unprecedented spatiotemporal resolution. We also discuss the reported applications of these tools in zebrafish and highlight the current challenges and future possibilities of opto-chemical approaches, particularly at the single cell level.

Phylogenetic and Expression Analysis of Fos Transcription Factors in Zebrafish

Members of the FOS protein family regulate gene expression responses to a multitude of extracellular signals and are dysregulated in several pathological states. Whilst mouse genetic models have provided key insights into the tissue-specific functions of these proteins in vivo, little is known about their roles during early vertebrate embryonic development. This study examined the potential of using zebrafish as a model for such studies and, more broadly, for investigating the mechanisms regulating the functions of Fos proteins in vivo. Through phylogenetic and sequence analysis, we identified six zebrafish FOS orthologues, fosaa, fosab, fosb, fosl1a, fosl1b, and fosl2, which show high conservation in key regulatory domains and post-translational modification sites compared to their equivalent human proteins. During embryogenesis, zebrafish fos genes exhibit both overlapping and distinct spatiotemporal patterns of expression in specific cell types and tissues. Most fos genes are also expressed in a variety of adult zebrafish tissues. As in humans, we also found that expression of zebrafish FOS orthologs is induced by oncogenic BRAF-ERK signalling in zebrafish melanomas. These findings suggest that zebrafish represent an alternate model to mice for investigating the regulation and functions of Fos proteins in vertebrate embryonic and adult tissues, and cancer.