Sample Submission Guidelines
What is Polysome-Seq?
In modern molecular biology, gene expression research has moved far beyond simply quantifying mRNA levels. The translation process—where ribosomes decode mRNA blueprints into proteins—accounts for over half of all gene regulatory events, exerting a profound influence on cellular behavior, protein function, and disease development. Yet traditional transcriptomic methods often fall short in revealing the true landscape of protein synthesis, creating gaps between measured mRNA abundance and actual protein production.
Polysome sequencing (Polysome-seq) bridges this critical gap. By combining polysome profiling with high-throughput sequencing, Polysome-seq offers researchers a comprehensive, quantitative snapshot of how ribosomes engage with thousands of mRNAs across diverse biological conditions. It unveils dynamic insights into translational regulation, enabling precise exploration of gene expression at the level where proteins—the ultimate effectors of cellular function—are actually produced.How Polysome Profiling Works
Polysome profiling is an analytical method that separates cytoplasmic RNA based on the number of ribosomes bound to each mRNA molecule. Utilizing sucrose gradient ultracentrifugation, cellular lysates are fractionated into distinct layers representing:
- Free mRNA (not engaged in translation)
- 40S and 60S ribosomal subunits
- 80S monosomes (single ribosomes)
- Light and heavy polysomes (multiple ribosomes translating a single mRNA)
A Comparison of Translational Omics Technologies
Translational research has expanded to include several high-resolution technologies, each offering unique insights:
| Technology | Core Focus | Key Advantages | Limitations |
|---|---|---|---|
| Polysome Profiling / Polysome-seq | Measures ribosome occupancy to infer translation efficiency. | - Direct translation efficiency measurement - Retains longer RNA fragments for downstream analysis |
- Larger sample input required - No ribosome positional data |
| Ribo-seq (Ribosome Profiling) | Maps precise ribosome positions on mRNA at codon resolution. | - Detects start sites, ORFs, uORFs - Reveals translational pausing and dynamics |
- Technically complex - Cannot distinguish active vs. stalled ribosomes |
| RNC-seq (Ribosome-Nascent Chain Complex Sequencing) | Captures full-length mRNAs bound to ribosomes. | - Preserves entire mRNA structure - Detects alternative splicing isoforms |
- Lacks ribosome positional information - Lower resolution of translation dynamics |
| Disome-seq | Detects ribosome collisions and translational pauses. | - Illuminates co-translational regulatory events | - Specialized, newer technique with fewer applications |
| TRAP-seq | Isolates ribosome-bound mRNAs in specific cell types via tagged ribosomes. | - Cell- or tissue-specific translation profiling | - Requires transgenic models - Possible interference with ribosome function |
Among these technologies, Polysome-seq stands out as an ideal compromise—it preserves RNA integrity, reveals translation efficiency across the transcriptome, and enables integrative analysis alongside transcriptomics, epitranscriptomics, and proteomics.
We offer a full suite of translational profiling services, including Polysome-seq, Ribo-seq, RNC-seq, Disome-seq, and TRAP-seq, to meet diverse research needs across all areas of molecular biology.
Our Polysome Sequencing Workflow: From Sample to Insight
1. Consultation & Experimental Design
Every project starts with a detailed discussion between our scientific team and your research group to:
- Define your biological questions and hypotheses.
- Select appropriate experimental conditions, controls, and replicates.
- Choose between single-fraction or multi-fraction polysome sequencing strategies.
- Align your project with publication-quality standards.
2. Sample Preparation & Ribosome Stabilization
- Cells or tissues are harvested and treated with translation elongation inhibitors (e.g., cycloheximide) to freeze ribosomes in place.
- Rapid processing under RNase-free conditions preserves ribosome-mRNA complexes and prevents degradation.
3. Polysome Profiling via Sucrose Gradient Ultracentrifugation
- Cytoplasmic extracts are layered onto a linear sucrose gradient (typically 10-50%).
- Ultracentrifugation separates mRNA-ribosome complexes based on density, yielding fractions that distinguish.:
- UV absorbance profiling precisely defines the peaks corresponding to each fraction.
4. Fraction Collection & RNA Extraction
Individual gradient fractions are collected, either:
- As a single "pooled polysome fraction" (for cost-effective global profiling).
- Or as multiple fractions (light vs. heavy polysomes) for deeper resolution of translational shifts.
- RNA is extracted from each fraction, ensuring high integrity for downstream sequencing.
5. Library Preparation & Next-Generation Sequencing
RNA undergoes:
- rRNA depletion or poly-A selection (depending on study goals).
- Fragmentation and adapter ligation.
- Reverse transcription and library amplification.
Bioinformatics Analysis & Data Interpretation
Bioinformatics Excellence
- Rigorous quality control and filtering
- Alignment to reference genomes or transcriptomes
- Transcript quantification across fractions
- Calculation of Translation Efficiency (TE)
- Differential translation analysis between conditions
- Integration with:
- RNA-seq
- Epitranscriptomics (e.g., m6A, m7G)
- Proteomics
Deliverables include:
- Publication-ready charts and figures
- Comprehensive statistical reports
- Expert interpretation tailored to your study goals
Sample Requirements
| Sample Type | Minimum Amount | Notes |
|---|---|---|
| Mammalian cell lines | ≥ 4 × 10⁷ cells | Cultured under standard conditions; avoid over-confluency. |
| Animal tissues | ≥ 400 mg | Snap-freeze immediately after dissection. |
| Plant tissues | ≥ 400 mg | Remove excess water before freezing. |
| Bacterial cultures | ≥ 4 × 10⁷ cells | Harvest during log phase for optimal ribosome activity. |
| Fungal cultures | ≥ 4 × 10⁷ cells | Ensure proper homogenization prior to lysis. |
| Isolated ribosome complexes | Variable; inquire | Custom protocols available for specialized projects. |
Sample Handling Guidelines
- Snap-freeze samples in liquid nitrogen immediately after harvesting.
- Store at -80°C until shipping.
- Ship on dry ice to maintain RNA integrity.
- Clearly label all tubes and provide a detailed sample sheet.
- Avoid repeated freeze-thaw cycles.
What You'll Receive from Our Polysome Sequencing Service
- Raw FASTQ files from high-throughput sequencing.
- BAM alignment files mapped to reference genomes or transcriptomes.
- Quantified gene expression data across polysome fractions.
- Translation Efficiency (TE) calculations for each transcript.
- Lists of genes showing differential translation between conditions.
- Polysome profile plots illustrating ribosome occupancy.
- Volcano plots and heatmaps for visualizing translation changes.
- Optional multi-omics integration with RNA-seq, epitranscriptomics, or proteomics.
- A comprehensive technical report with methods, results, and interpretations.
- Direct access to our scientists for data review and project discussions.
Why Choose Our Polysome Sequencing Service?
Unmatched Translational Insights
- Go beyond mRNA abundance to see how genes are truly expressed at the protein synthesis level.
- Capture global translation dynamics and pinpoint regulatory bottlenecks in diseases, stress responses, and developmental processes.
Flexibility for Diverse Research Goals
- Single-fraction or multi-fraction options for customized depth of analysis.
- Compatible with a wide range of organisms, from mammalian cells to plants and microbes.
- Ultra-low-input protocols available for precious or limited samples.
Seamless Multi-Omics Integration
Integrate polysome data with:
- Transcriptomics (RNA-seq)
- Epitranscriptomics (e.g., m6A, m7G modifications)
- Proteomics
- Gain a holistic view of gene expression regulation.
Publication-Ready Deliverables
- High-quality figures and statistical analyses crafted for scientific journals.
- Clear documentation and methods sections suitable for manuscript inclusion.
Expert Scientific Support
- Direct access to PhD-level scientists with extensive experience in translational research.
- Personalized guidance from experimental design through data interpretation.
- Rapid response times to keep your project moving.
Proven Track Record
- Supported hundreds of publications in peer-reviewed journals.
- Trusted by researchers worldwide in academia, pharma, and biotechnology.
Applications of Polysome Sequencing
Cancer Research – Discover translational reprogramming driving tumor progression and therapy resistance.
RNA Modifications Studies – Uncover how m6A, m7G, and other modifications influence translation efficiency.
Neurobiology – Investigate translational control in neural development, plasticity, and neurodegenerative diseases.
Plant Science – Study stress responses, development, and yield traits at the translational level in crops.
Metabolic Research – Examine translation shifts during metabolic disorders and nutrient sensing.
Stem Cell Differentiation – Explore translational landscapes guiding cell fate decisions.
Microbial Physiology – Analyze bacterial and fungal translational regulation under environmental changes.
Non-Coding RNA Translation – Detect hidden peptides from lncRNAs, circRNAs, and other ncRNAs.
Stress Response Mechanisms – Profile global translation changes under heat shock, oxidative stress, or hypoxia.
Drug Mechanism Studies – Assess how therapeutic compounds impact translational efficiency and ribosome engagement.
Frequently Asked Questions
1. What is Polysome‑Seq and how does it work?
Polysome‑Seq merges polysome profiling with RNA sequencing to assess translational status across the transcriptome—separating light and heavy ribosome‑associated fractions and quantifying their mRNA content for translation efficiency analysis.
2. How does Polysome‑Seq differ from Ribo‑seq?
Polysome‑Seq profiles the number of ribosomes on each mRNA, offering a view of global translation. In contrast, Ribo‑seq maps ribosome footprint positions at codon resolution—ideal for detecting start sites, uORFs, and paused translation.
3. Can Polysome‑Seq detect translation of non-coding RNAs?
Yes. By sequencing longer mRNA fragments from polysome fractions, Polysome‑Seq can capture actively translated lncRNAs, circRNAs, and other ncRNAs, revealing hidden peptides.
4. What sample types are compatible with Polysome‑Seq?
Common samples include cultured cells, animal or plant tissues, bacteria, fungi, and even purified ribosome complexes. Proper sample handling and ribosome stabilization are essential.
5. Is specialized equipment required?
Yes. Polysome profiling relies on ultracentrifugation, gradient fractionation, and UV detection. These steps demand technical expertise and high-quality reagents—precisely what our team provides.
6. What bioinformatics analyses are included?
Our pipeline includes data QC, genome/transcriptome alignment, transcript quantification, TE calculation, differential translation analysis, and visualizations. Integration with RNA‑seq, epitranscriptomics, or proteomics is also available for a comprehensive translational profile.
7. What are the limitations of Polysome‑Seq?
Potential challenges include large sample input requirements and moderate RNA recovery efficiency. Additionally, positional ribosome data is not provided—unlike Ribo‑seq.
8. Can Polysome‑Seq and Ribo‑seq be used together?
Absolutely. Combining both yields a holistic view: Polysome‑Seq reveals translational engagement, while Ribo‑seq offers detail on ribosome positioning and non-canonical translation events.
9. How is polysome profile data interpreted?
Profiles display ribosome distribution across mRNA via UV absorbance peaks. The ratio of polysomes to monosomes indicates translational activity. Subsequent sequencing enables quantitative translation efficiency analysis.
10. What quality control measures are in place?
We implement rigorous checks at each stage—UV profile reproducibility, RNA integrity (RIN score), library quality metrics, and bioinformatics quality control. These ensure reliable, high-impact results.
Title: METTL5 stabilizes c-Myc by facilitating USP5 translation to reprogram glucose metabolism and promote hepatocellular carcinoma progression
Source: Xia et al., Cancer Communications, 2023
Impact Factor: 20.1
Study Background
- METTL5 is an 18S rRNA methyltransferase.
- Scientists suspected METTL5 might promote cancer by affecting how certain mRNAs are translated into proteins.
- Focus was on c-Myc, a critical oncogene, and USP5, a deubiquitinase that stabilizes c-Myc.
Key Research Questions
- Does METTL5 affect c-Myc protein levels through translational regulation?
- How does this influence cancer cell metabolism?
Methods Used
✅ Polysome Profiling + RNA-Seq
- Separated mRNAs into fractions based on ribosome loading.
- Sequenced polysome-bound mRNAs to assess translation efficiency.
✅ qRT-PCR and Western Blot
- Verified changes in RNA levels and protein levels.
✅ ChIP Assay & Metabolomics
- Explored regulatory mechanisms and metabolic shifts.
✅ Patient-Derived Xenografts (PDX)
- Validated findings in animal tumor models.
Major Findings
- METTL5 upregulates translation of USP5 mRNA, resulting in higher USP5 protein levels.
- USP5 stabilizes c-Myc protein by reducing its degradation.
- Elevated c-Myc drives increased glycolytic gene expression (e.g. LDHA, ENO1).
- Knockdown of METTL5 leads to reduced tumor growth in mice.
Impact of Polysome Sequencing
Polysome sequencing was critical because:
- Standard RNA-seq alone wouldn't reveal increased translation efficiency of USP5.
- Only by analyzing ribosome-loaded fractions did researchers detect how METTL5 boosts USP5 production.
- Helped link RNA methylation (via METTL5) to metabolic reprogramming—a key cancer hallmark.
USP5 is the deubiquitinating enzyme for c-Myc.
Why It Matters
✅ Polysome-seq uncovers translational regulation invisible to transcriptomics alone.
✅ Enables discovery of therapeutic targets like METTL5.
✅ Shows real impact in disease contexts, from molecular mechanisms to tumor outcomes.
