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Oligopaint DNA-FISH Service: High-Resolution 3D Chromatin Imaging

Accelerate your chromatin research with our full-stack Oligopaint DNA-FISH service. We provide custom probe design, high-resolution imaging, and quantitative 3D distance analysis to validate Hi-C loops, map enhancer-promoter interactions, and visualize structural variations with single-cell precision. RUO.

  • Orthogonal validation for Hi-C/Micro-C contacts
  • < 50 nm localization precision with super-resolution
  • Custom probes for any annotated genome (Human/Mouse/Plant)
  • Quantifiable deliverables: 3D distances & spatial distributions
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3D fluorescence in situ hybridization (FISH) showing chromatin loops and enhancer-promoter contacts in a cell nucleus.

Overview: Visualizing the 3D Genome with Nanometer Precision

Our Oligopaint DNA-FISH Service provides a comprehensive solution for the direct visualization and quantification of genomic organization in single cells. While sequencing-based methods like Hi-C sequencing and Micro-C infer population-averaged contact frequencies, they often require orthogonal validation to confirm physical proximity in native nuclear environments. We bridge this gap by combining computationally designed oligonucleotide probes with high-resolution microscopy to map specific chromatin interactions, enhancer-promoter loops, and structural variations (SVs).

Designed for biopharma R&D and academic research, our service operates on a Research Use Only (RUO) basis. We deliver a closed-loop workflow—from custom in silico probe design to quantitative image analysis—ensuring you receive publication-ready data to validate your 3D genomics findings. By utilizing massively parallel oligonucleotide synthesis, we generate probes that are highly specific, free of repetitive elements, and capable of targeting genomic regions ranging from a few kilobases to multiple megabases with tunable density.

  • Single-Cell Resolution: Resolve chromatin folding heterogeneity and cell-to-cell variability masked by bulk sequencing.
  • High Specificity: Proprietary probe design algorithms minimize off-target binding in repetitive regions, ensuring high signal-to-noise ratios.
  • Quantitative Metrics: Deliverables include 3D spatial coordinates, radial positioning data, and pairwise distance distributions (nm).

Why Choose CD Genomics for Spatial Imaging?

  • Expertise in 3D Genomics: We are not just an imaging core; we are experts in chromatin biology, understanding how to integrate FISH data with Hi-C and ChIP-Seq.
  • Custom Design Capabilities: Our bioinformatics team can design probes for challenging regions, including gene clusters and breakpoints, where commercial catalog probes fail.
  • Rigorous QC: We validate probe efficiency and include positive/negative controls in every run to distinguish true interactions from background noise.
  • Data-Driven Deliverables: We provide the raw numbers (coordinates, distances), not just images, enabling you to perform your own statistical tests.

Service Highlights

Orthogonal Validation

Sequencing biases (e.g., ligation efficiency, PCR amplification) can introduce artifacts in Hi-C maps. Oligopaint DNA-FISH provides a non-enzymatic, imaging-based method to physically verify loop existence, offering the "gold standard" confirmation required by top-tier journals.

Super-Resolution Capability

Standard confocal microscopy is limited by the diffraction limit (~250 nm). We offer Super-Resolution Microscopy (SIM/STORM) options to achieve localization precision down to 20–50 nm, enabling the separation of tightly clustered enhancer-promoter pairs and fine-scale chromatin folding domains.

Flexible Probe Design

Unlike BAC clones which are fixed to specific genomic libraries, our Oligopaint probes are custom-synthesized. We can target any annotated genome (Human, Mouse, Zebrafish, Plants) and design probes against specific SNPs, breakpoints, or novel isoforms.

Quantitative Image Analysis

We move beyond qualitative "pretty pictures." Our bioinformatics pipeline automates nuclei segmentation, spot detection, and 3D distance calculation across thousands of cells, providing statistically robust datasets (p-values, distance distributions) rather than just representative images.

Technical Comparison: Oligopaint vs. Traditional BAC Probes vs. Hi-C

Feature Oligopaint DNA-FISH Traditional BAC Probes Hi-C Sequencing
Resolution Very High (<5-10 kb targets, <50 nm precision) Low (>100 kb targets, diffraction limited) Variable (depends on sequencing depth)
Specificity Single-nucleotide precision (computationally filtered) Low (prone to repetitive element binding) High (sequence based)
Throughput Targeted (1-10 loci per cell) Targeted (1-3 loci) Genome-wide (All-vs-All)
Signal-to-Noise High (eliminates repeat-associated background) Moderate to Low N/A (Sequencing noise)
Output Physical 3D Distances (nm) & Images Qualitative Images Contact Frequencies (Counts)
Flexibility Fully custom (any genome) Limited to library availability Universal protocols

Notes:

  • Use Oligopaint DNA-FISH when you need to validate specific structural features or interactions with high spatial precision.
  • Traditional BAC probes are suitable for larger chromosomal aberrations but lack the resolution for fine-scale loop mapping.
  • Hi-C is best for discovery and genome-wide mapping, while FISH provides the necessary validation and single-cell resolution.

Workflow – Step-by-Step Oligopaint Procedure

We employ a standardized QC and delivery pipeline to ensure reproducibility and data integrity.

1. Consultation & In Silico Design

We define the biological question (e.g., verifying a 50kb loop). Our team uses OligoMiner and proprietary algorithms to scan the target sequence, identifying unique, non-repetitive binding sites. We balance probe density (probes per kb) and thermodynamic properties to ensure uniform hybridization. Deliverable: Design report with probe coverage maps.

2. Probe Synthesis & Amplification

We synthesize a complex library of thousands of oligonucleotides. These are amplified via PCR using specific primers that append a T7 promoter (for RNA synthesis) or binding sites for secondary detection. We convert the library into single-stranded DNA (ssDNA) or RNA probes tailored for the specific FISH protocol.

3. Sample Preparation & Fixation

Cells are fixed using paraformaldehyde (PFA) optimized to preserve 3D nuclear architecture while allowing probe penetration. For specific tissue types, we employ specialized permeabilization protocols (e.g., freeze-thaw cycles, enzymatic digestion) to ensure robust signal.

4. Hybridization & Imaging

Probes are hybridized to the denatured genomic DNA overnight. We use primary or secondary labeling strategies with robust fluorophores (Alexa 488, 568, 647, Atto dyes). Imaging is performed on calibrated Confocal or Super-Resolution (SIM/STORM) microscopes, acquiring Z-stacks to capture the full nuclear volume. QC Check: Signal-to-noise ratio assessment and specificity verification.

5. Quantitative Image Analysis

Raw image data is processed using automated pipelines. We perform: Nuclei segmentation (DAPI), Spot detection (Gaussian fitting), Chromatic aberration correction, and Calculation of 3D Euclidean distances between center-of-mass coordinates.

6. Final Reporting

We deliver a comprehensive report containing raw images, processed coordinate files, and QC metrics.

Oligopaint DNA-FISH service workflow including probe design, synthesis, imaging, and data analysis.

Technical Specifications

We offer flexible formats to match your resolution and throughput needs.

Specification Details
Probe Size Typical target region size: 5 kb – 2 Mb. Probe length: 30-40 nt (homology region).
Labeling Options Direct labeling (fluorophore on oligo) or Indirect (Secondary binding). Colors: DAPI (Nucleus), Green, Red, Far-Red (3-4 channels).
Microscopy Platforms Laser Scanning Confocal (Standard), Airyscan, Structured Illumination Microscopy (SIM), STORM (Single Molecule Localization).
Localization Precision Confocal: ~200 nm XY, ~500 nm Z.
SIM: ~100 nm XY, ~250 nm Z.
STORM: ~20-50 nm XY.
Cell Throughput Standard analysis: >100 cells per condition. High-throughput automated imaging: >1000 cells.

Sample Requirements

Sample Type Recommended Input Storage/Transport Notes
Suspension Cells 2 - 5 million cells Cryopreserved (DMSO) or Fixed Pellet Avoid over-fixation; verify viability >90% before fixation.
Adherent Cells 1-2 x T25 flasks or Coverslips Fixed on coverslips or Cryopreserved Grow cells to 70-80% confluence; do not overgrow.
Fresh Tissue 50 - 100 mg Flash frozen / RNAlater Requires single-cell dissociation optimization.
FFPE Blocks 10 - 20 slides (4-5 μm) Room Temperature Signal quality depends on fixation quality; antigen retrieval may be needed.

Key Applications: From Loop Validation to SV Detection

Our service is optimized for researchers investigating chromatin structure-function relationships, specifically for validating targets identified by high-throughput sequencing.

Validating Enhancer-Promoter Interactions (V2G)

Functional genomics relies on accurately linking non-coding regulatory elements to their target genes. We use multicolor Oligopaint DNA-FISH to measure the physical distance between putative enhancers and promoters. This provides orthogonal evidence to support interactions detected by HiChIP or Micro-C, crucial for "Variant-to-Gene" (V2G) assignment in drug discovery. We can distinguish between "active" loops (close proximity) and "poised" or "broken" loops in different cell states.

Resolving Structural Variations (SVs) & Breakpoints

Complex structural variants, such as inversions, translocations, or copy number variations (CNVs), can reshape the 3D genome. Our service designs probes flanking predicted breakpoints to visualize the rearranged architecture. For example, by painting the region upstream and downstream of a breakpoint in different colors, we can visualize fusion events or inversions that are difficult to resolve with short-read sequencing alone.

Characterizing TADs & Nuclear Compartments

We enable the visualization of Topologically Associating Domains (TADs) and sub-TAD structures. By tiling probes across a genomic region, we can physically map domain boundaries and assess their stability. Furthermore, we can map the radial position of specific loci to determine if they reside in the transcriptionally active nuclear interior or the repressive nuclear periphery (lamina-associated domains).

Single-Cell Heterogeneity Studies

Bulk Hi-C provides an ensemble average. Oligopaint FISH reveals the true frequency of an interaction within the population. We can quantify what percentage of cells actually exhibit a specific loop structure, providing insights into the stochastic nature of gene regulation and cell-state heterogeneity.

Key Deliverables

Our deliverables are designed to be "figure-ready" for publications and grants.

Raw Data Files
High-resolution multi-channel microscopy images (Z-stacks in .czi, .lif, or .tiff format).

Processed Data Tables
CSV/Excel files containing 3D coordinates (x, y, z) for every detected spot in every cell.

Summary Report
Includes Panel A: Representative images (Maximum Intensity Projections) with scale bars; Panel B: 3D reconstruction models of chromatin paths; Panel C: Pairwise Distance Histograms showing the distribution of physical distances (nm) between probes.

Probe Design Files
BED files containing genomic coordinates of all oligonucleotides used.

Case Study: Validating Enhancer-Promoter Dynamics at Pluripotency Loci

Researchers sought to validate whether chromatin loops identified by Hi-C at the Nanog and Sox2 loci corresponded to physical proximity in mouse embryonic stem cells (mESCs), and how this proximity changed upon differentiation.

Custom Oligopaint probes were designed to target the Nanog promoter and its putative distal super-enhancer (-45 kb). 3D-FISH was performed on wild-type mESCs and differentiated cells. Imaging was conducted using 3D-SIM super-resolution microscopy to resolve fine-scale spatial structures.

Quantitative image analysis of >500 cells revealed that the median spatial distance between the Nanog promoter and its enhancer was significantly shorter (~180 nm) in pluripotent cells compared to differentiated cells (>300 nm). The frequency of co-localization (defined as <200 nm separation) correlated strongly with transcriptional output measured by RNA-seq.

Data showing enhancer-promoter distance measurements from Oligopaint DNA-FISH experiments.

Oligopaint DNA-FISH provided the critical orthogonal validation needed to link 3D chromatin conformation (loops) to gene expression states, confirming the regulatory mechanism suggested by sequencing data.

(Source: Adapted from Nanoscale dynamics of enhancer–promoter interactions, NAR 2025)

Demo Results (Representative Examples)

  • High-resolution, multi-channel microscopy images (Z-stacks) showing the nucleus (DAPI) and targeted loci (FISH spots).
  • Rendered 3D models of the chromatin path for select nuclei.
  • Histograms and violin plots showing the distribution of physical distances (in nm) between two probes across the population.
  • Analysis of the loci's position relative to the nuclear periphery or nucleolus.

Multi-color fluorescence microscopy image showing nuclei with distinct red/green spots.Panel A: Raw Imaging

A 3D reconstructed model of the chromatin path.Panel B: 3D Reconstruction

A histogram chart titled 'Pairwise Distance Distribution' showing shifting peaks.Panel C: Distance Analysis

Frequently Asked Questions

References

  1. Nanoscale dynamics of enhancer–promoter interactions during exit from pluripotency. Nucleic Acids Research. 2025.
  2. Versatile design and synthesis platform for visualizing genomes with Oligopaint FISH probes. PNAS. 2012.
  3. Oligopaint FISH to Study Chromosomal Architecture and Structural Variations. Methods Mol Biol. 2025.
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High-confidence 3D genomics services for chromatin interaction analysis and regulatory insight.

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