Variable Length Barcode Tags for Nucleic Acid Quantitation
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Solution Overview
Problem
Next-generation sequencing technologies face challenges in extracting quantitative information regarding the absolute or relative abundance of nucleic acids from small samples, particularly due to difficulties in accurately estimating the abundance of target nucleic acids using unique molecular identifiers (UMIs).
Innovation Solution
A method involving covalently linking variable length barcode tags to target nucleic acid molecules and introducing a transposase fragmentation site and transposon end, creating a unique molecular barcode that allows for the estimation of nucleic acid abundance through high-throughput sequencing by providing a sufficient number of unique molecular identifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional unique molecular identifiers (UMIs) are used for nucleic acid quantitation, then sequencing can be performed, but the number of unique barcodes is insufficient leading to poor quantitation accuracy
Solution Approach 1:
The barcode is divided into multiple independent components: a fixed-length sequence portion and a variable-length insertion portion. The variable-length portion is created by inserting different numbers of nucleotides (0-10 nt) at a specific site, generating 2^11 = 2048 unique barcodes from a single primer sequence. This segmentation approach exponentially increases barcode diversity without requiring proportionally more primer sequences.
Solution Approach 2:
The invention adds a new dimension to barcode diversity by incorporating variable length (0-10 nucleotides) in addition to the fixed sequence. This transforms the barcode space from a one-dimensional sequence variation to a two-dimensional space combining sequence identity and length variation, dramatically expanding the number of unique identifiers that can be generated from limited primer sequences.
2Measurement precision
If more unique molecular identifiers are generated to improve quantitation, then measurement precision improves, but the complexity of the barcoding system increases
Solution Approach 1:
The variable-length insertion sequence is pre-designed and integrated into the primer structure before the actual barcoding process. The primer contains a designated insertion site with flanking sequences that guide the variable-length insertion. This preliminary preparation allows the complex barcode diversity to be achieved through a simple, standardized insertion process rather than requiring complex assembly of multiple different primers.
Solution Approach 2:
The invention changes the parameter of barcode length (0-10 nucleotides) as a controllable variable to generate diversity. By systematically varying this single parameter while keeping the rest of the barcode structure constant, the system achieves high complexity in barcode identification while maintaining simplicity in the overall barcoding methodology and data analysis pipeline.
3Measurement precision
If variable length barcode tags are used to increase unique identifiers, then nucleic acid abundance estimation improves, but the difficulty of detecting and measuring barcodes increases
Solution Approach 1:
The invention replaces complex mechanical or chemical barcode attachment methods with a streamlined biochemical insertion process. The variable-length barcode is inserted through a standardized molecular biology technique (e.g., Gibson assembly or ligation) at a defined site in the nucleic acid. This substitution simplifies the detection process because all barcodes share the same structural context and flanking sequences, allowing uniform sequencing and bioinformatic analysis regardless of the inserted length.
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 enables accurate absolute or relative quantitation of target nucleic acids, achieving >90% quantitation efficiency by providing a large number of unique barcodes, thus overcoming the limitations of existing methods in nucleic acid abundance estimation.
Implementation Method 1
contacting the target nucleic acid molecules with a plurality of transposases, such that a transposase fragmentation site and a covalently linked transposon end is introduced at a second end of the individual target nucleic acid molecules
Implementation Method 2
extending the primers with a polymerase, thereby producing a plurality of double-stranded variable length barcode-tagged target nucleic acid molecules
Data Source
AI summary
Methods and compositions are provided for making and using uniquely tagged target nucleic acid molecules.