Oligonucleotide Primer Design for Small RNA cDNA Synthesis
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Solution Overview
Problem
Existing methods for synthesizing and amplifying cDNA from small RNAs, such as miRNAs, face challenges in sensitivity and specificity due to the short length of these RNAs, making it difficult to design effective primers for reverse transcription and PCR.
Innovation Solution
A method involving a first oligonucleotide molecule that hybridizes to the 3' end of target RNA and a second oligonucleotide molecule that hybridizes to the 5' side of the first region, allowing for the extension of cDNA beyond the original RNA length, enhancing accuracy and specificity in cDNA synthesis and amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a primer is designed to hybridize to both ends of cDNA obtained by reverse transcription of miRNA, then amplification by PCR can be performed, but it is difficult to design such a primer because the nucleotide length of miRNA is as short as about 20 bases
Solution Approach 1:
The primer is divided into two distinct regions: a first region (about 10-15 bases) that hybridizes to the miRNA template, and a second region (about 10-20 bases) that extends beyond the miRNA length to provide a sufficient target for PCR amplification. This segmentation allows each region to fulfill its specific function independently, resolving the contradiction between primer design ease and amplification reliability.
Solution Approach 2:
The primer design extends into a new dimension by incorporating a second region that goes beyond the traditional miRNA length. This additional dimensional extension provides the necessary length for effective PCR amplification while maintaining the original miRNA-specific hybridization capability in the first region.
2Productivity
If existing methods (EP 1 851 336 B or US 7,575,863) are used to synthesize cDNA from small RNA, then cDNA amplification can be performed, but sensitivity and specificity are insufficient
Solution Approach 1:
The primer is designed with different local qualities in its two regions: the first region has high specificity for the target miRNA sequence, while the second region provides extended homology for robust PCR amplification. This local differentiation optimizes both the sensitivity of detection and the efficiency of amplification simultaneously.
3Productivity
If the primer length is extended beyond the miRNA length to facilitate PCR amplification, then amplification can be performed, but the primer may hybridize to non-specific targets reducing specificity
Solution Approach 1:
By segmenting the primer into a miRNA-specific first region and an extension second region, the invention ensures that the critical specificity function is confined to the first region which hybridizes only to the complementary miRNA sequence, while the second region provides the necessary length for amplification without compromising overall specificity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the sensitivity and specificity of cDNA synthesis and amplification from small RNAs, allowing for more accurate detection and quantification of target RNAs, as demonstrated by real-time PCR results showing lower limits of detection and quantification compared to previous methods.
Implementation Method 1
the first oligonucleotide molecule has a first region that hybridizes to the target RNA at the 3' end
Implementation Method 2
has a second region that hybridizes to the second oligonucleotide molecule on the 5' side (i.e. 5') of the first region
Implementation Method 3
synthesizing cDNA by mixing a target RNA, a first oligonucleotide molecule, a second oligonucleotide molecule, and a reverse transcriptase, using the target RNA as a template
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
Disclosed is a method for synthesizing cDNA by mixing a target RNA, a first oligonucleotide molecule, a second oligonucleotide molecule, and a reverse transcriptase, using the target RNA as a template, the first oligonucleotide molecule having a first region that hybridizes to the target RNA at 3' end, and having a second region that hybridizes to the second oligonucleotide molecule on 5' side of the first region.