RESEARCH Fluorescent-Based Methods for Gene Knockdown and Functional Cardiac Imaging in Zebrafish

The Author(s) 2013. This article is published with open access at Springerlink.com Abstract A notable advantage of zebrafish as a model organism is the ease of gene knockdown using morpholino antisense oligonucleotide (MO). However, zebrafish mor-phants injected with MO for a target protein often show heterogeneous phenotypes, despite controlling the injection volume of the MO solution in all embryos. We developed a method for estimating the quantity of MO injected into each living morphant, based on the co-injection of a control MO labeled with the fluorophore lissamine. By applying this method for knockdown of cardiac troponin T (tnnt2a) in zebrafish, we could efficiently select the partial tnnt2a-depleted zebrafish with a decreased heart rate and impair-ment of cardiac contraction. To investigate cardiac impairment of the tnnt2a morphant, we performed fluo-rescent cardiac imaging using Bodipy-ceramide. Cardiac image analysis showed moderate reduction of tnnt2a impaired diastolic distensibility and decreased contraction and relaxation velocities. To the best of our knowledge, this is the first report to analyze the role of tnnt2a in cardiac function in tnnt2a-depleted living animals. Our combina-torial approach can be applied for analyzing the molecular function of any protein associated with human cardiac diseases