FISH can be used to detect specific gene signatures in intact organisms – without nucleic acid extraction, PCR and gene sequencing. FISH can be evaluated by fluorescence microscopy, flow cytometry or by other methods. Some of the main benefits of FISH is that the morphology of the targeted object remains intact and that its distribution and association to others can be evaluated in the natural environment. FISH is used worldwide in medical science, life science, and biotechnology.
Examples of publications using the FISH technics in different projects
FISH method description
Fluorescence In Situ Hybridization (FISH) was developed in the 1980s and together with PCR and gene sequencing, these methods revolutionized many fields in biology (from chromosomal diagnostics to the many fields in microbiology, ecology and biotechnology). Today, PCR, gene sequencing and omic´s have become the most common diagnostic methods, simply because they are easier to automate and provide precise quantitative data. However, these methods are not seldom time consuming and bias-free, they also fail to describe relevant parameters such as morphology, distribution and association between different objects in their own environment.
Usefulness of FISH
FISH is a relatively fast and straightforward method and can thus complement the PCR and gene sequencing/omic´s diagnostic approach in several ways:
quick identification (from 1 to 96 h, depending on target and goal) of different kinds of intact cells (Archaea, Bacteria, Eukarya) and to some extent viruses;
pre-screening method prior to time-consuming techniques;
follow-up method for specific questions based on a large amount of data;
combination with a multitude of other methods.
Principle of FISH
In simple terms, FISH can be regarded as a phylogenetic staining method, as it is based on gene probes that are designed to target specific gene sequences. These gene probes are labeled with different kinds of markers – mostly fluorochromes. Since several different gene probes can be used simultaneously in one FISH experiment, different gene targets can therefore be easily distinguished by different colours. FISH experiments can be evaluated by different techniques, such as with microscopy and flow cytometry.
Disadvantages of FISH
Successful FISH depends on several parameters, such as optimal penetration of gene probes through the cell wall, amount of gene copy numbers of the intended gene target, stringent and specific gene probes, and a non-fluorescent background. If these demands are not met, different kinds of biases may arise. To overcome such obstacles, a plethora of different kinds of FISH protocols have been developed.
Requirements for FISH / service suggestions
Appropriate fixation and storage of sample prior to FISH
Detailed knowledge about the phylogeny and suitability of the gene probes
Selection of appropriate FISH protocols
Selection of suitable references and controls
Selection of suitable detection technique
Performance and evaluation of FISH experiments
Evaluation options of FISH results
FISH can be evaluated in different ways and combined with other methods for optimal retrival of additional information.
Options available at Umeå University are:
Fluorescence microscopy (BICU, other SciLifeLab facilities?),
Electron microscopy (UCEM, other SciLifeLab facilities?),