A rapid and simple procedure for the isolation and cultivation of fibroblast-like cells from medaka and zebrafish embryos and fin clip biopsies

Establishment of cell lines from individual zebrafish embryos

With the increasing use of fish as model species for research, cell cultures derived from caudal fin explants as well as pre-hatching stage embryos have provided powerful in vitro tools that can complement or serve as an ethically more acceptable alternative to live animal experiments. The widely-used protocols to establish these lines require, as a starting point, homogeneous pools of embryos or viable adult fish which are large enough for collecting sufficient fin tissue. This excludes the use of fish lines with adverse phenotypes or lines that exhibit mortality at early developmental stages and so can only be propagated as heterozygotes. Specifically, when no visually overt mutant phenotype is detectable for identifying homozygous mutants at early embryonic stages, it is then impossible to sort pools of embryos with the same genotypes to generate cell lines from the progeny of a heterozygote in-cross. Here, we describe a simple protocol to generate cell lines on a large scale starting from individual early embryos that can subsequently be genotyped by polymerase chain reaction. This protocol should help to establish fish cell culture models as a routine approach for the functional characterization of genetic changes in fish models such as the zebrafish. Furthermore, it should contribute to a reduction of experiments which are ethically discouraged to avoid pain and distress.

A minimally invasive fin scratching protocol for fast genotyping and early selection of zebrafish embryos

Current genetic modification and phenotyping methods in teleost fish allow detailed investigation of vertebrate mechanisms of development, modeling of specific aspects of human diseases and efficient testing of drugs at an organ/organismal level in an unparalleled fast and large-scale mode. Fish-based experimental approaches have boosted the in vivo verification and implementation of scientific advances, offering the quality guaranteed by animal models that ultimately benefit human health, and are not yet fully replaceable by even the most sophisticated in vitro alternatives. Thanks to highly efficient and constantly advancing genetic engineering as well as non-invasive phenotyping methods, the small zebrafish is quickly becoming a popular alternative to large animals' experimentation. This approach is commonly associated to invasive procedures and increased burden. Here, we present a rapid and minimally invasive method to obtain sufficient genomic material from single zebrafish embryos by simple and precise tail fin scratching that can be robustly used for at least two rounds of genotyping already from embryos within 48 h of development. The described protocol betters currently available methods (such as fin clipping), by minimizing the relative animal distress associated with biopsy at later or adult stages. It allows early selection of embryos with desired genotypes for strategizing culturing or genotype-phenotype correlation experiments, resulting in a net reduction of "surplus" animals used for mutant line generation.