skip to content

Cambridge Stem Cell Institute

 

Please find some of our commonly asked questions and answers below.

If you don't find what you're looking for, feel free to contact Maike Paramor at mp600@cam.ac.uk or the facility account at ngs-core@jcbc.cam.ac.uk.

Which buffer should be used to resuspend cells in preparation for a 10X Genomics Single Cell RNA sequencing experiment?

Cells should be washed a minimum of two times and resuspended in 1X PBS (calcium and magnesium-free) with 0.04% BSA. Solutions should not contain EDTA and surfactants as they will inhibit further reactions. Alternative buffers can be found here.

How do I count my cells before submitting?

It is very important that we receive the correct number of cells in the correct volume. For accurate cell counting, please refer to this guide and this page.

What cell diameter is compatible with the 10X Genomics Single Cell platform?

10X recommends using cells with a diameter of up to 30µm. For larger cells, it is recommended to use nuclei instead.

How can I prevent dead cells and debris in my sample?

A 40 µm Flowmi Cell Strainer can be used to reduce the prevalence of aggregates within a cell suspension. To avoid incorporating noisy data from dead cells in your experiment, 10X Genomics provides a demonstrated protocol for dead cell removal.

What if I have a request that is not on your list?

We will always try and accommodate new protocols that we have not previously done. It makes our work exciting and may benefit other groups eventually. Contact us at ngs-core@jcbc.cam.ac.uk

Can I sort my cells prior to running through the 10x Single Cell assay?

Yes, FACS samples are compatible with the 10x Single Cell workflow. It is a good method to enrich for specific cell types based on cell surface markers, and to get a clean cell suspension as it also removes the dead cells and debris. For some tips about best practises go here.

How do I submit my samples?

Please contact us to arrange a handover, and please fill in the online submission form here.

How should samples be prepared for Visium HD?

We can either process FFPE samples form human or mouse tissues, or we can process fresh frozen/fixed frozen tissues from any organism with the 3’HD assay. Guidelines about tissue preparation to either of these processes are found here and here. Tissue sectioning, fixation, staining, and imaging can be performed at the JCBC Histology core facility, which you should contact in advance.

How much does it cost?

For smaller projects, we can provide a price calculator. We will prepare quotations for larger projects and grant applications. Please contact us at ngs-core@jcbc.cam.ac.uk for details

What are your turnaround times?

It will depend on the type of project, but in general we are aiming to have all incoming projects fulfilled within 2-3 weeks. This might be longer at especially busy times.

Who can access the facility?

The NGS facility prioritises projects from the Cambridge Stem Cell Institute, however, we are also accepting a wide range of projects from across the University, and from external contacts.

How will I receive the sequencing data?

Once your sequencing run has finished, we will send you information on how to download the data over FTP. The output will be the FASTQ files, and some quality reports and demultiplexing statistics.

Do you provide bioinformatics support?

Unfortunately, we cannot provide bioinformatic support.

How much data do I need?

It depends on your individual requirements!
Here are some general guidelines for NGS libraries: https://emea.illumina.com/science/education/sequencing-coverage.html

For bulk transcriptome libraries, we generally sequence 20-50 million reads per sample.

A minimum of 20,000 read-pairs per cell are recommended for libraries constructed with the 10X Genomics single cell kits.

Visium HD samples will be sequenced according to the %coverage of the capture area.

What is the difference between the different Novaseq flowcells?

The Novaseq has different sized flowcells which adjust to different output needs. 1.5B flowcells have 2 lanes. 10B and 25B flowcells have 8 lanes.

Here is a table to illustrate the amount of paired end reads (in million) per lane.

Novaseq X

 

 

lane type

up to mio reads per lane

observed mio reads per lane

SLX_NovaSeqX_1.5B

750

1100

SLX_NovaSeqX_10B

1250

1400

SLX_NovaSeqX_25B

3100

4000

 

Does the NGS facility have any equipment that groups can access?
  • You can book the Bioanalyzers and the tapestation on PPMS. Please ask for training/access if necessary.
  • We can offer training or access to the Covaris E220 (https://www.covaris.com/e220 )
What do I do if my samples fail your QC?

We would normally ask you to either replace those samples that failed the QC, or continue the project without them. In some cases, it might be necessary to work with degraded RNA samples, and in those cases we have the appropriate kits available that deal with degraded RNA.

What recommendations are available for Single Cell preparations?

The 10X Genomics Cell Preparation Guide describes best practices and methods for washing, concentrating, resuspending, and counting cells.
Some useful information in this Q&A section.