Stress response and disease models
When a condition, a stage or a genotype changes, the modification profile usually shifts with it. Studies in this area compare the same sites and the same regions across the systems they work on, within one experiment.
01The question behind these studies
Stress, treatment and disease-model work asks how a modification pattern changes between conditions — before and after a stress, between disease stages, between a wild type and a mutant — and whether the change is specific to the transcripts or the sites that matter.
The comparison is the experiment. Both sides of it come from the same study and are read out the same way, which is what makes the difference between them interpretable rather than an artifact of handling.
Whether the answer sits at the level of a region or of a single nucleotide follows from the claim being made. A statement about one nucleotide needs a single-base method; a statement about a transcript, a pathway or a whole profile can be made from enrichment-based work.
02Which service line fits
Two lines carry most of this work, and which one fits depends on where the conclusion lands.
Single-Base RNA Modification Sequencing
Reports the individual site and its modification level, so a site can be compared between conditions at the same position.
Site-levelposition & level PROFILERNA Modification RIP-Sequencing
Profiles modification enrichment across transcripts, which suits a design with several conditions or a large sample set.
Condition setprofile MARK_13Dihydrouridine (D) Seq (CRACI-seq)
Base-resolution dihydrouridine calls, for studies where the mark being followed is dihydrouridine rather than m6A.
Site-levelD MARK_14O8G Modification Seq (O8G-miSeq)
Profiles 8-oxoguanine on miRNA and pri-miRNA at single-nucleotide resolution, the mark that oxidative stress experiments most often follow.
Site-levelO8G03What the project gets back
- Every condition read the same way. Calls or profiles for each system in the study, produced through one workflow, so the comparison is not carried by a difference in processing.
- Site-level difference tables. Modification at individual sites in each condition, with the level on both sides of the comparison rather than one averaged value.
- Region-level profiles. Where the enrichment line is used, the transcripts and the regions whose modification changes between the conditions.
- Functional context. The changed transcripts read against pathways and gene sets, so the shift can be placed against the biology being studied.
- Signal tracks. Genome-browser files that let a changed site or region be inspected against the transcript model.
The comparison only means something when it is made on the same position. A site that is modified under one condition and unmodified under another is a different statement from two neighbouring sites each measured once, and the reporting keeps the two apart.
04How a project is set up
- Define the comparison — the conditions, the samples in each and the mark — and keep it fixed while the study runs.
- Collect the material the same way for every condition. Total RNA, cells, tissue and blood are all accepted; blood is taken in EDTA tubes, since heparin is not compatible with the downstream procedure.
- Check each sample against the quality thresholds before the workflow: OD 260/280 at or above 1.8, RIN at or above 7, with no visible degradation.
- Process the conditions together rather than in separate rounds, so a difference between them is not produced by the order in which they were handled.
- Report the difference per site or per region, with the direction of the change, so the shift is readable against the condition it belongs to.
| Need | Request Quote |
|---|---|
| A condition or treatment series with several groups | |
| A disease model or genotype comparison | |
| Oxidative stress followed at O8G sites | |
| Base-resolution dihydrouridine profiling |
05FAQ
Is a change in modification level the same as a change at a site?
No, and the difference decides the method. A single-base method reports the level of one nucleotide in each condition, so a site can be followed across the study; an enrichment profile reports where modification signal is higher, which is a statement about transcripts and regions.
Can a condition series be compared in one project?
Yes. Time courses, dose series and several genotypes are run through the same workflow, and the conditions are processed together rather than in separate rounds, so a difference between groups is not produced by the order in which they were handled. The comparison is interpretable because every condition was measured the same way.
Which method fits oxidative stress work?
O8G-miSeq profiles 8-oxoguanine on miRNA and pri-miRNA at single-nucleotide resolution, which is the mark oxidative stress experiments most often follow. Where the mark of interest is a different one, the design questions are the same and the method follows the modification, so the choice is decided by the mark rather than by the stress model.
Do the conditions have to be collected at the same time?
Not necessarily, but they should be collected under one protocol and stored the same way, and each sample is checked against the quality thresholds before the workflow starts. Differences in handling and in storage show up as differences in modification, so the protocol is part of the design rather than a detail left to each site.