Clonal Pre-amplification in Emulsion for Bias-Free Nucleic Acid Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current nucleic acid amplification methods face challenges in efficiently amplifying small amounts of nucleic acid from single or few cells without distorting information content, particularly due to biases, errors, and limitations in PCR technology, such as preferential amplification of shorter fragments and GC-rich sequences, leading to differential representation of DNA populations.
Innovation Solution
A method involving clonal pre-amplification of nucleic acid molecules by attaching adaptor sequences to their ends, preparing a water-in-oil emulsion where each droplet contains one or none of the molecules, and performing PCR within these droplets to amplify them, ensuring unbiased amplification and maintaining representation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional PCR amplification is used to amplify small amounts of nucleic acid, then amplification efficiency is improved, but bias and distortion of information content occur
Solution Approach 1:
The invention segments the amplification process into two distinct phases: clonal pre-amplification in compartmentalized droplets (to generate sufficient material) and subsequent analysis (to preserve information integrity). This segmentation allows efficient amplification without the bias problems of conventional PCR by using isothermal strand-displacement amplification in isolated compartments, then analyzing the amplified products without further biased amplification.
Solution Approach 2:
The invention introduces an intermediary compartmentalization system using water-in-oil emulsion droplets as isolated reaction chambers. Each droplet acts as an independent intermediary environment that contains amplification reagents and template nucleic acids, preventing cross-contamination and bias while enabling efficient clonal amplification through strand-displacement mechanisms without the competitive dynamics of conventional PCR.
2Quantity of substance
If PCR amplification is used to amplify nucleic acid from single or few cells, then sufficient material for analysis is obtained, but preferential amplification of shorter fragments and GC-rich sequences occurs
Solution Approach 1:
The invention changes the fundamental parameters of the amplification reaction by using isothermal conditions (constant temperature) instead of thermal cycling, and strand-displacement amplification instead of competitive PCR. These parameter changes eliminate the preferential amplification of shorter or GC-rich sequences that occurs in conventional PCR, as the isothermal strand-displacement mechanism amplifies all sequences with equal efficiency regardless of length or composition.
Solution Approach 2:
The invention performs preliminary clonal amplification in compartmentalized droplets before final analysis. This preliminary action generates sufficient quantity of nucleic acid material from single or few cells while maintaining accurate representation, because the strand-displacement amplification occurs in isolated compartments without the competitive dynamics that cause bias in conventional PCR.
3Adaptability or versatility
If in vitro transcription amplification is used, then RNA samples can be amplified, but the method is time-consuming and produces less stable amplificates
Solution Approach 1:
The invention replaces the multi-step mechanical process of in vitro transcription (cDNA synthesis, RNA synthesis, purification) with a streamlined isothermal DNA amplification process. By using strand-displacement amplification of cDNA templates, the method eliminates the time-consuming transcription steps while maintaining the ability to amplify RNA samples, reducing total amplification time and producing more stable DNA amplificates.
4Productivity
If exponential PCR amplification is used, then high amplification yields are achieved, but saturation occurs with excess input template quantities
Solution Approach 1:
The invention segments the amplification into clonal pre-amplification (to achieve high yield from low input) and linear enrichment (to maintain reliability). The compartmentalized droplet system enables each template molecule to undergo independent clonal amplification, achieving high yields without saturation effects because each droplet processes individual templates separately. Subsequent linear enrichment maintains the proportional representation of different templates.
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 allows for accurate and unbiased amplification of nucleic acid sequences from minimal samples, enabling effective gene expression analysis and maintaining the representation of all types of nucleic acid molecules, even from as few as one cell, with high accuracy and precision.
Implementation Method 1
preparing a water in oil emulsion characterized in that the majority of water droplets comprises one or none member of said plurality of different nucleic acid molecules
Data Source
AI summary
Disclosed is a process for clonal pre-amplification of a nucleic acid involving the steps of (i) providing a plurality of different nucleic acid molecules (b) attaching adaptor sequences to the 3′ ends and 5′ ends of the nucleic acid molecules (c) preparing a water in oil emulsion wherein the majority of water droplets comprises one or none member of the plurality of different nucleic acid molecules (d) clonally amplifying the plurality of different nucleic acid molecules. In particular, the different nucleic acid molecules are mRNA molecules.