RNA-Seq Frequently Asked Questions

General Questions

1. What is RNA-Seq?

RNA-Seq is a method for transcriptome profiling that uses next generation sequencing technologies. RNA-Seq provides a comprehensive, quantitative, and unbiased view of RNA sequences within every sample, and is the most powerful tool currently available for analyzing gene expression.

For more information, download our eBook A Guide to RNA-Seq or read our article Which RNA-Seq Technique Should I Use?

2. What starting materials are accepted?

We recommend starting with total RNA. However, we have extensive experience performing extractions from a wide variety of materials, including cell pellets, fresh frozen tissue, blood, and FFPE slides.

We also accept sorted cells for Ultra-Low Input RNA-Seq. Check out our Sample Submission Guidelines for more information.

3. What method is used to remove ribosomal RNA?

Since ribosomal RNA (rRNA) makes up the majority of total RNA, its removal is necessary for efficient sequencing of other RNA species, such as mRNA, long non-coding RNA (lncRNA), and small RNA.

For Standard and Strand-Specific RNA-Seq, you can select either poly-A selection or rRNA depletion methods. Poly-A selection is sufficient for studying mRNA in eukaryotes. Analysis of lncRNA or bacterial transcripts requires rRNA depletion.
For Ultra-Low Input RNA-Seq, the default is to use poly-A selection. However, if your project requires analysis of lncRNA in addition to mRNA, please make a comment on the quote request form, and we can discuss the available options.

4. How many reads do I need for my experiment?

The number of reads required depends upon the genome size, the number of known genes, and transcripts. Generally, we recommend 5-10 million reads per sample for small genomes (e.g. bacteria) and 20-30 million reads per sample for large genomes (e.g. human, mouse). Medium genomes often depend on the project, but we would generally recommend between 15-20 million reads per sample. For de novo transcriptome assembly projects, we recommend 100 million reads per sample.

5. What bioinformatics services are available for RNA-Seq projects?

We provide raw data as FASTQ files for all projects. We also have advanced bioinformatics capabilities to provide optional data analysis services, including:

Standard RNA Analysis Package: mapping, differential gene expression, alternative splicing, and gene ontology analysis
Gene fusion discovery
SNP/INDEL detection
Novel transcript discovery
De novo transcriptome assembly for sequences that do not have a reference

6. How does Single-Cell RNA-Seq differ from Standard and Ultra-Low Input RNA-Seq?

Standard RNA-Seq produces a representative snapshot of the transcriptional state averaged across all cells. The caveat with traditional RNA-Seq is the resolution of individual cells and cellular subpopulations are lost. Single-Cell RNA-Seq allows researchers to not only identify cellular subpopulations, but to fully interrogate them at the single-cell level within a heterogeneous sample.

Similar to Standard RNA-Seq, Ultra-Low Input RNA-Seq provides bulk expression analysis of the entire cell population; however, as the name implies, a very limited amount of starting material is used, as low as 10 pg or a few cells. Single-Cell RNA-Seq requires at least 50,000 cells (1 million is recommended) as an input.

For more information, read our articles:

Top 3 Factors to Consider for Single-Cell Sequencing

How Single-Cell Sequencing Works

7. What sequencing platforms are used for RNA-Seq?

Standard, Strand-Specific, Single-Cell, Small, and Ultra-Low Input RNA-Seq use short-read sequencing on Illumina^® platforms, such as the NovaSeq and HiSeq. Iso-Seq uses long-read sequencing on the PacBio^® Sequel^®.

8. How does Illumina-based RNA-Seq compare to Iso-Seq on PacBio?

Generally, Iso-Seq is superior to Illumina approaches when qualitative endpoints are of interest, such as alternative splicing, alternative polyadenylation, genome annotation, and novel transcript detection. For quantitative assessment (e.g. expression of transcript A vs B in one sample, or expression of transcript C in sample 1 vs sample 2), short-read-approaches are recommended due to the greater number of reads that can be obtained.

9. Can you analyze small RNA or miRNA?

Yes, select our Small RNA-Seq service. Please note that our library preparation for Small RNA-Seq uses kits that specifically recognize the 5’ and 3’ ends of RNA after processing by DICER. A different library preparation method is used for Standard RNA-Seq projects for analysis of mRNA and lncRNA.

10. Can you prepare small and standard RNA libraries from the same total RNA preparation?

Yes, if enough input material is provided and the total RNA preparation contains small RNAs. Since Standard RNA-Seq and Small RNA-Seq use different library preparation methods, the total RNA sample must be split.

11. How do I contact GENEWIZ for a technical consultation about my project?

GENEWIZ's NGS Team is composed of Ph.D. scientists who can help you optimize your project design and provide consultation. Contact the team via email at ngs.europe@genewiz.com or call us at +49 (0)341 520 122-41.

12. Can you recommend the best data delivery option?

Yes, we can recommend the best data delivery option based on the platform and project details. Options include:

Secure File Transfer Protocol (sFTP)
Customer Cloud Account
Hard Drive (additional charges may apply)

13. How will my data be delivered?

If your results are being shipped to you via hard drive, you can track its shipment using the tracking number provided to you in the delivery email sent from GENEWIZ.

If your results are being delivered via another data delivery method, such as AWS S3, Aspera, or other cloud-based methods, please refer to the delivery email sent from GENEWIZ for detailed information on the transfer, and consult with your IT department to ensure compliance with your institution’s policies.

If your results are being sent via a secure File Transfer Protocol (sFTP), please refer to GENEWIZ’s sFTP Data Download Guide for instructions on how to download your data and troubleshooting tips.

14. What is the price for RNA-Seq?

Please submit a quote request to receive accurate pricing information, as the cost depends on the details of the project.

Sample Preparation

15. How should I prepare and send my samples?

View our Sample Submission Guidelines for instructions on preparing and sending your samples for RNA-Seq. Ship samples directly to our facility. Use the shipping address listed on the order receipt.

16. What happens if my samples do not meet your starting material requirements?

Please contact us via email at ngs.europe@genewiz.com or call us at +49 (0)341 520 122-41.

Order & Processing

17. How do I request a quote?

For European customers, please use one of the following forms to request RNA-Seq.

18. How long do you hold samples?

We hold samples for 1 year after project completion. Please contact us if you would like samples retained for a longer period of time or shipped back to you.

RNA Sequencing Frequently Asked Questions

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