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Monday, July 6, 2026

Tempus Blood RNA Tubes: Why Collection Timing Matters

July 06, 2026 0 Comment

RNA has transformed the way we study biology.

Unlike DNA, which provides a relatively static blueprint of an organism, RNA reveals which genes are actively being expressed at a particular moment. Measuring RNA therefore allows researchers to investigate how cells respond to disease, infection, drugs, environmental stimuli and many other biological processes.

However, there is one major challenge.

RNA is remarkably unstable.

The moment blood is collected, the molecular profile inside the sample begins to change. Genes continue to be switched on and off, while enzymes naturally present within blood rapidly begin degrading RNA. Unless these processes are stopped immediately, the RNA extracted from the sample may no longer accurately represent the biological state of the patient at the time of collection.

This is why preserving RNA begins long before the RNA extraction kit is opened.

It begins at the point of blood collection.

Why RNA degrades so quickly

One reason RNA is more difficult to work with than DNA is that it is highly susceptible to degradation.

Cells contain enzymes called ribonucleases, commonly known as RNases, whose role is to break down RNA molecules once they have served their purpose. RNases are extremely stable enzymes and are found almost everywhere. They are present within blood cells, on laboratory surfaces, on skin and even in tiny amounts of environmental contamination.

Once blood leaves the body, these enzymes continue to function.

At the same time, blood cells remain metabolically active for a period after collection. Gene expression does not stop immediately, meaning the RNA profile within the sample continues to change.

As time passes, the sample becomes progressively less representative of the patient's original biological condition.

For studies investigating gene expression, these changes can introduce significant experimental variation.

The importance of immediate RNA stabilisation

The ideal blood sample for transcriptomic analysis is one in which gene expression has been preserved exactly as it existed inside the patient.

Achieving this requires two things to happen as quickly as possible.

First, blood cells must be lysed so that their RNA is released.

Second, RNases must be inactivated before they have an opportunity to degrade the RNA.

Only then can the original gene expression profile be preserved for downstream molecular analysis.

This is precisely the problem that Tempus™ Blood RNA Tubes were designed to solve.

How Tempus™ Blood RNA Tubes work

Unlike a conventional blood collection tube, a Tempus™ Blood RNA Tube already contains approximately 6 mL of RNA stabilising reagent before blood is collected. The tube is calibrated to collect approximately 3 mL of whole blood.

Once the correct volume of blood enters the tube and is mixed immediately, the stabilising reagent rapidly lyses the blood cells.

Cell lysis releases intracellular RNA into the solution.

At the same time, RNases are inactivated, preventing RNA degradation. The stabilising chemistry also promotes selective precipitation of RNA, preserving the original gene expression profile until RNA extraction is performed.

Rather than allowing biological processes to continue after collection, the tube effectively captures a molecular snapshot of the patient's blood at that precise moment.

Why collecting the correct blood volume matters

It may seem that collecting slightly more or slightly less blood would have little consequence.

In reality, the ratio between blood and stabilising reagent is carefully optimised.

Collecting too little blood means the sample becomes excessively diluted, while overfilling the tube reduces the relative amount of stabilising reagent available.

Either situation may compromise efficient cell lysis or complete RNA stabilisation, potentially affecting RNA yield and quality.

For this reason, Tempus™ Blood RNA Tubes are designed to collect approximately 3 mL of whole blood and should not be overfilled or underfilled.

Why immediate mixing is the most critical step

Perhaps the most important step in the entire collection process occurs only seconds after the blood has been drawn.

The tube must be mixed immediately.

This is not simply to blend the contents.

Immediate vigorous mixing ensures that every portion of the collected blood comes into rapid contact with the stabilising reagent. Uniform exposure allows blood cells to lyse quickly, RNases to be inactivated and RNA stabilisation to begin without delay.

If mixing is delayed, even for a relatively short period, some cells may remain intact while gene expression continues to change. RNases may also begin degrading RNA before the stabilising reagent has fully dispersed throughout the sample.

The consequence is that the RNA extracted later may no longer accurately reflect the patient's biological state.

For this reason, the collection procedure specifies vigorous shaking for approximately 10 to 20 seconds immediately after blood collection, making this the critical step in the workflow.

Why storage conditions remain important

Although RNA is stabilised immediately after collection, proper storage remains essential.

RNA stabilisation prevents rapid degradation, but samples must still be stored under validated conditions to maintain long-term integrity.

Tempus™ Blood RNA Tubes can be stored at room temperature for several days, refrigerated for longer periods or frozen at −80 °C for long-term preservation. Repeated freeze–thaw cycles should be avoided because they may reduce sample quality over time.

Appropriate storage provides flexibility for laboratories transporting samples from collection sites to central testing facilities without compromising RNA quality.

Why sample quality determines data quality

RNA extraction cannot restore RNA that has already degraded.

Regardless of how sophisticated the downstream molecular techniques may be, the quality of the final data depends on the quality of the original specimen.

Poorly stabilised samples may produce reduced RNA yields, lower RNA integrity and altered gene expression profiles. These changes can influence downstream analyses such as reverse transcription quantitative PCR (RT-qPCR), RNA sequencing, transcriptomic profiling and biomarker discovery.

By contrast, properly collected and stabilised samples provide a reliable foundation for accurate and reproducible molecular analysis.

Getting RNA collection right from the start

Modern molecular biology increasingly depends on measuring gene expression rather than simply identifying DNA sequences.

As a result, preserving RNA has become one of the most important aspects of blood sample collection.

Tempus™ Blood RNA Tubes simplify this process by combining blood collection with immediate RNA stabilisation. When the correct blood volume is collected, the tube is mixed immediately and samples are stored under appropriate conditions, researchers can be confident that the extracted RNA closely reflects the patient's biology at the moment the blood was drawn.

In molecular diagnostics and transcriptomic research, high-quality data begin not during RNA extraction, but with the very first seconds after blood collection.

What Is Next-Generation Sequencing? NGS vs Sanger Explained
Learn how high-quality RNA samples are used in next-generation sequencing and why RNA integrity is critical for reliable sequencing data: https://adwoabiotech.blogspot.com/2026/06/what-is-next-generation-sequencing-ngs.html
Oxford Nanopore Sequencing: A Different Philosophy of Reading DNA
Discover how nanopore sequencing differs from conventional sequencing technologies and its applications in modern molecular biology: https://adwoabiotech.blogspot.com/2026/06/what-is-oxford-nanopore-sequencing-how.html
Sanger Sequencing Explained: How One Missing Oxygen Changed DNA Sequencing Forever
Explore the chemistry behind chain-terminating nucleotides and how Sanger sequencing revolutionised DNA sequencing: https://adwoabiotech.blogspot.com/2026/06/sanger-sequencing-explained-how-one.html

References

1. Tanner MA, Berk LS, Felten DL, Blidy AD, Bit SL, Ruff DW. Substantial changes in gene expression level due to the storage temperature and storage duration of human whole blood. Clin Lab Haematol 2002; 24:337-341.

2. Rainen L, Oelmuller U, Jurgensen S, Wyrich R, Ballas C, Schram J, et. al. Stabilization of mRNA expression in whole blood samples. Clin Chem 2002; 48:1883-1890.

Wednesday, May 13, 2026

Antisense RNA Explained: Why Strand-Specific RNA-Seq Matters

May 13, 2026 0 Comment

The Two Strands of DNA Do Not Carry the Same Information: Antisense RNA and Why Strand-Specific RNA-Seq Changed Everything

For the longest time, I subconsciously assumed the two strands of DNA carried the same biological information.

Not identical sequences, obviously. We all learn early on that DNA strands are complementary:

A pairs with T.
G pairs with C.

But conceptually, I still thought of one strand as essentially a mirrored backup copy of the other. Same information, just reversed.

Then I properly encountered antisense RNA and strand-specific RNA sequencing.

And suddenly I realised something that completely changed how I visualise genomes:

The opposite strand of DNA can encode entirely different biological information.

Not just regulatory signals. Entirely different RNAs. Sometimes entirely different proteins.

The Textbook Version vs Reality

Most of us are taught transcription something like this:

DNA → RNA → Protein

A gene sits on DNA. RNA polymerase reads it. mRNA is produced. Protein gets made.

But real genomes are much messier than that.

Genes can overlap. Transcription can occur in both directions. RNAs can regulate other RNAs. Some RNAs are never translated at all. And sometimes the "opposite" strand of DNA contains completely different instructions.

What Is Antisense RNA?

To understand antisense RNA, we first need to separate two ideas:

Sense strand
The DNA strand whose sequence matches the RNA transcript (except T is replaced with U).

Antisense strand (template strand)
The DNA strand actually used by RNA polymerase as the template during transcription.

Already, the naming is confusing enough to give undergraduate students mental strain.

But here’s the important part:

An RNA molecule can also be produced from the opposite DNA strand in the reverse direction.

That RNA is called an antisense RNA.

This means you can have something like this:

One strand producing a normal protein-coding mRNA
The opposite strand producing a completely different RNA transcript

And because the sequences are complementary, the RNAs can physically interact with one another.

That interaction can:

block translation,
alter chromatin structure,
regulate transcription,
or affect RNA stability.

In other words, antisense RNAs are not necessarily transcriptional "noise". They can have real biological functions.

The moment the light bulb came on for me was realising this:

The opposite DNA strand is not just a passive complementary copy.

It can contain:

different promoters,
different transcription start sites,
different open reading frames,
and entirely different regulatory information.

That means the genome is not one-dimensional.

It is layered, so strand direction becomes critically important.

One of the Most Famous Examples: XIST and TSIX

A classic example comes from X chromosome inactivation in mammals.

Female mammals have two X chromosomes, but one must be largely silenced to prevent double dosage of X-linked genes.

This process is controlled by a long non-coding RNA called XIST.

XIST coats one X chromosome and helps silence it.

Interestingly, another RNA called TSIX is transcribed from the opposite strand across the XIST locus.

TSIX is an antisense transcript.

And rather than being meaningless background transcription, TSIX helps regulate XIST expression itself.

So you end up with a regulatory system where:

XIST promotes X chromosome silencing
TSIX regulates XIST
both arising from opposite strands of the same genomic region

A classic paper by Navarro et al. (2005) showed that TSIX transcription alters chromatin conformation at the XIST locus, highlighting that antisense transcription itself can have regulatory consequences.

At this point, the idea that DNA is simply a static storage medium starts to feel very incomplete.

Scientists Initially Thought Antisense Transcription Was Mostly Noise

And honestly, this assumption made sense at the time.

Early transcriptomics methods often struggled to determine which DNA strand an RNA came from. Researchers could detect transcriptional signal, but not always its orientation.

So when overlapping or opposite-direction transcripts appeared, many scientists assumed they were:

transcriptional errors,
random polymerase activity,
or biological noise.

Then strand-specific RNA sequencing methods became more widely adopted.

And suddenly researchers realised antisense transcription was everywhere.

Not just in humans.
Not just in weird edge cases.

Entire layers of genome regulation had been hiding in plain sight simply because earlier methods collapsed strand information together.

Why Ordinary RNA-Seq Can Cause Problems

This is where strand-specific RNA-seq becomes incredibly important.

In conventional (non-stranded) RNA-seq, you can sequence RNA transcripts perfectly well, but you may lose information about which DNA strand they originally came from.

That becomes a major problem when:

genes overlap,
antisense RNAs exist,
or neighbouring genes are transcribed in opposite directions.

Imagine two genes sitting on opposite strands of DNA:

One goes left → right
The other goes right → left

If your RNA-seq data is not strand-specific, all the sequencing reads can appear merged together.

You may detect transcription in that region, but you cannot confidently determine:

which gene produced the RNA,
whether both genes are active,
or whether antisense transcription is occurring.

That ambiguity can completely alter biological interpretation.

Strand-Specific RNA-Seq Preserves Directionality

Strand-specific RNA-seq solves this problem by preserving transcript orientation during library preparation.

In simple terms, it tells you:

"This RNA came from THIS DNA strand."

That sounds like a tiny technical detail but having that information changes how we interpret:

gene boundaries,
overlapping loci,
antisense transcription,
non-coding RNAs,
and transcript abundance.

This is especially important in compact genomes where genes are tightly packed together.

Without strandedness, transcriptional landscapes can become blurred.

The Bioinformatics Consequences Are Huge

If you accidentally analyse stranded RNA-seq data using the wrong strand settings during alignment or counting, you can:

invert expression signals,
assign reads to the wrong genes,
underestimate transcript abundance,
or completely miss antisense transcription.

In other words:
your computational interpretation becomes biologically wrong.

This is why bioinformaticians care so much about strandedness metadata in RNA-seq experiments.

It is not computational nitpicking: it fundamentally affects what the data means.

For me, the most fascinating part of all this is philosophical as much as technical.

At school and university, DNA is often presented as though genes sit neatly along a chromosome like words written left-to-right in a book.

But real genomes are far stranger than that.

They are:

bidirectional,
overlapping,
dynamic,
and deeply layered.

The two strands of DNA are not redundant copies carrying the same biological information.

They can encode entirely different transcripts with entirely different functions.

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