Use of zebrafish (Danio rerio) as a model for research in toxicological studies

Danio rerio, commonly known as zebrafish, is a freshwater aquarium fish and is native to parts of South Asia. It is considered an important organism for analyzing the noxious effects of toxicants and pollutants of the environment. In terms of the molecular signaling pathway, molecular properties, organ functions and structures, and neurogenesis, zebrafish are similar to certain other higher-order vertebrates. The 3Rs, refinement,reduction, and replacement in researchhavegradually evolved with time. The accumulation of toxicants in the environment and the human health conditions from exposure to toxicants present in the environment is a serious concern, and zebrafish serves as an excellent model to research such effects. The three Rs are met by zebrafish, larvae can also be used to discover harmful medication compounds, permitting safer compounds to be explored in model organisms and it could also be used to substitute certain toxicological testing.Also, because embryos are fertilized outside and are visible during the initial days of life, the early larval model of zebrafish enables flexibility to animal research study, subsequently reducing the number of animals employed in experiments.For various experimentation studies, the larva of the zebrafish is proved to be a useful model for the system.Thus, being a good test system, zebrafish are used in environmental health and safety studies.This review focuses on the toxicological studiesin zebrafish and outlines the toxicological studies done on zebrafish with arsenic and 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) as well as microplastic toxicity.

New Tricks for an Old (Hedge)Hog: Sonic Hedgehog Regulation of Astrocyte Function

The Sonic hedgehog (Shh) molecular signaling pathway is well established as a key regulator of neurodevelopment. It regulates diverse cellular behaviors, and its functions vary with respect to cell type, region, and developmental stage, reflecting the incredible pleiotropy of this molecular signaling pathway. Although it is best understood for its roles in development, Shh signaling persists into adulthood and is emerging as an important regulator of astrocyte function. Astrocytes play central roles in a broad array of nervous system functions, including synapse formation and function as well as coordination and orchestration of CNS inflammatory responses in pathological states. Neurons are the source of Shh in the adult, suggesting that Shh signaling mediates neuron–astrocyte communication, a novel role for this multifaceted pathway. Multiple roles for Shh signaling in astrocytes are increasingly being identified, including regulation of astrocyte identity, modulation of synaptic organization, and limitation of inflammation. This review discusses these novel roles for Shh signaling in regulating diverse astrocyte functions in the healthy brain and in pathology.

Dysregulated Translation in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with complex genetic architecture and heterogeneous symptomatology. Increasing evidence indicates that dysregulated brain protein synthesis is a common pathogenic pathway involved in ASD. Understanding how genetic variants converge on a common molecular signaling pathway in neurons and brain circuits, resulting in ASD-relevant synaptic and behavioral phenotypes, is of great interest in the autism research community. This article focuses on ASD-risk genes and the molecular aspects leading to dysregulated protein synthesis.

Raman observation of a molecular signaling pathway of apoptotic cells induced by photothermal therapy

A molecular signaling pathway of apoptosis induced by photothermal therapy was revealed by surface-enhanced Raman spectroscopy.

Annelids shed light on the evolution of spiralian development

Spiralian development is characterized by stereotypic cell geometry and spindle orientation in early cleavage stage embryos, as well as conservation of ultimate fates of descendent clones. Diverse taxa such as molluscs, annelids, flatworms, and nemerteans exhibit spiralian development, but it is a mystery how such a conserved developmental program gives rise to such diverse body plans. This review highlights examples of variation during early development among spiralians, emphasizing recent experimental studies in the annelid Capitella teleta Blake, Grassle and Eckelbarger, 2009. Intracellular fate mapping studies in C. teleta reveal that many of its cells’ fates are shared among spiralians, but it also has a novel origin for trunk mesoderm (3c and 3d micromeres). Studies have identified an inductive signal in spiralians that has “organizing activity” and that influences cell fates in the surrounding embryo. Capitella teleta also has an organizing activity; however, surprisingly, it is localized to a different cell, it signals at a different developmental stage, and likely utilizes a distinct molecular signaling pathway compared with that in molluscs. A model is presented to provide a mechanistic explanation of evolutionary changes in the cellular identity of the organizer. Detailed experimental investigations in spiralian embryos demonstrate variation in developmental features that may influence the evolution of novel forms.

Gene expression of components of the insulin/insulin-like signaling pathway in response to heat stress in the garter snake, Thamnophis elegans

The insulin/insulin-like signaling (IIS) pathway is an evolutionary conserved molecular signaling pathway that regulates growth, reproduction, stress resistance, and longevity in response to nutrition and external stress. While the constituents of this pathway and their functions are relatively well understood in laboratory model animals, they have not been explored in many other organisms, with notable exceptions in the fisheries literature. We tested for the gene expression of four key components of this pathway in the garter snake (Thamnophis elegans) liver, and determine how the transcription of these components responds to heat stress. We found that the two insulin-like growth factor ligands (IGF-1 and IGF-2) and the receptors (IGF-1 Receptor and M6P/IGF-2 Receptor, or IGF-1R and IGF-2R) are expressed in garter snake liver tissue. Under normal laboratory conditions, IGF-2 and IGF-2R are expressed at a higher level than IGF-1 and IGF-1R. In response to heat stress, IGF-1 expression remained the same, IGF-2 expression decreased, and the expression of both receptors increased. These results demonstrate that elements of the IIS pathway are responsive to heat stress in snakes. Further studies are needed to fully understand the biological consequences of this response.