In Situ Hybridization (ISH) refers to the process in which a labeled nucleic acid probe of known sequence hybridizes with target nucleic acids within cells or tissue sections, enabling precise localization and quantification of specific nucleic acid sequences. The basic principle relies on the ability of two single-stranded nucleic acid fragments to form double-stranded molecules, such as DNA-DNA, DNA-RNA, or RNA-RNA, through hydrogen bonding under appropriate conditions. Labeled DNA or RNA probes (radioisotopes, fluorophores, biotin, digoxigenin, or other non-radioactive labels) are hybridized with nucleic acids (RNA or DNA) in cells or tissue sections. Detection is performed using autoradiography or other visualization methods to observe and localize the target mRNA or DNA under light or electron microscopy.

Fluorescence in situ hybridization replaces isotopic labeling with fluorescent labeling, making the method safer and more economical. Additionally, probes labeled with different fluorophores can be used simultaneously to detect multiple sequences within the same sample.

Fluorescent labeling of FISH probes can be performed using direct or indirect methods. Indirect labeling involves biotin-labeled DNA probes detected via fluorescently tagged avidin or streptavidin, often amplified using an avidin–biotin–fluorophore complex. Direct labeling covalently attaches fluorophores to nucleotides or the sugar-phosphate backbone of the probe, or incorporates fluorescent nucleotide triphosphates during nick translation labeling. While direct labeling simplifies the detection process, it is less sensitive than indirect labeling due to the absence of signal amplification.

FISH is characterized by rapidity, high sensitivity, and specificity. It allows simultaneous quantitative analysis of multiple cells in both metaphase and interphase; detection of cryptic or microstructural chromosomal abnormalities and complex karyotypes; and visualization of DNA fragments and genes, including their relative positions and orientations with precise spatial resolution.

Figure 1 Schematic diagram illustrating the principle of gene localization in the nucleus using FISH (Fluorescence In Situ Hybridization).

We offer FISH Services covering a wide range of research areas, including human, animal, plant, and microbial studies. Based on specific customer requirements, our technical experts provide professional one-on-one customized solutions and detection services for samples from different species, delivering strong support for research projects. For example, Microbial FISH Detection Services involve detecting and identifying microbial rRNA, enabling in situ detection, identification, and selection of specific bacterial and archaeal groups.

-- Relevant information of the samples to be tested.

-- Relevant information or sequence of the target gene to be tested.

-- Sample quantity information.

-- Detection requirements.

Our technical experts provide a comprehensive customized Fluorescence In Situ Hybridization (FISH) service, ranging from probe design and chromosome/cell/bacteria preparation/culture to final result presentation. For details, please fill out our inquiry form or contact our staff directly.

-- Remaining probes, slides, and samples.

-- Original hybridization and staining images.

-- A detailed experimental report (including complete workflow and result analysis).

-- High-specificity probe design services.

-- Short service timeline (1–2 weeks) with precise localization, delivering results promptly.

-- Broad detection range covering human, animal, plant, and microbial samples.

-- Imaging tailored to customer needs.

-- Capability to visualize up to three colors (red, green, and blue) simultaneously in a single nucleus for multiplex sequence detection.