ALS-associated genes display CNS expression in the developing zebrafish

Amyotrophic lateral sclerosis (ALS) is characterized by progressive muscle atrophy resulting from the deterioration of motor neurons in the central nervous system (CNS). Recent genome-wide association studies have revealed several genes linked to ALS, further demonstrating the complexity of the disease. The zebrafish (Danio rerio) is an attractive model organism to study the function of the rapidly expanding number of ALS-associated genes, in part, due to the development of genome editing techniques that have facilitated specific gene targeting. Before investing in the manipulation and phenotypic examination of these genes, however, it is important to ascertain the localization of expression in this organism. We performed an expression analysis of 29 total ALS-linked genes in the developing zebrafish, specifically focusing on those genes that displayed robust and reproducible expression at multiple different timepoints. First, we classified a subset of the most robustly expressed genes into three distinct groups: head-only expression, head and weak trunk expression, and head and robust trunk expression. Then, we defined the characteristic pattern of each gene at 2, 3, and 4 days post fertilization. This analysis will facilitate improved mutant phenotype assessment in zebrafish by focusing researchers on the areas of expression.