Dual Pulse Nucleic Acid Labeling Without Wash Steps
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Solution Overview
Problem
Current methods for dual pulse labeling of DNA require an intermediary wash step, which introduces artifacts affecting quantification of DNA synthesis, making it challenging to measure baseline and changes in cellular nucleic acid synthesis without disrupting the cellular environment.
Innovation Solution
A method involving the use of two or more nucleoside analogs with bioorthogonal functional moieties, such as ethynyl-deoxyuracil (EdU) and 5-bromo 2′-deoxyuridine (BrdU), that can be incorporated into nucleic acid without the need for a wash step, allowing for simultaneous or sequential labeling without interrupting cellular processes, using bioorthogonal reactions like [3+2] cycloaddition or Staudinger ligation for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intermediary wash step is used in dual pulse labeling of DNA, then the labeling process can be completed, but artifacts are introduced that affect quantification of DNA synthesis
Solution Approach 1:
The patent removes the problematic intermediary wash step from the dual pulse labeling process by using nucleoside analogs with orthogonal detection methods. The first pulse label (e.g., BrdU) is detected through antibody binding, while the second pulse label (e.g., EdU) is detected through click chemistry with a different detection mechanism, eliminating the need for washing that causes artifacts.
Solution Approach 2:
The patent introduces orthogonal detection systems as intermediaries between the two pulse labels. The first label uses antibody-based detection while the second label uses bioorthogonal chemistry (click chemistry or Staudinger ligation), allowing both labels to be detected simultaneously without cross-interference and without requiring disruptive wash steps.
2Measurement precision
If a wash step is performed between pulse labels, then the first label can be removed, but cellular processes are disrupted
Solution Approach 1:
The patent enables continuous labeling of cellular DNA without interruption by using two nucleoside analogs that can be detected through orthogonal methods. Cells remain in culture throughout the dual pulse labeling process, maintaining continuous cellular processes and natural DNA synthesis patterns without the disruption of removal and addition cycles.
Solution Approach 2:
The patent allows cells to continuously incorporate both pulse labels into their DNA through their own natural DNA replication machinery. The orthogonal detection systems automatically distinguish between the two labels without requiring external intervention to remove one label before adding the other, making the process self-sustaining and non-disruptive.
3Reliability
If traditional BrdU labeling is used, then DNA incorporation can be detected, but the process requires antibody treatment and washing steps
Solution Approach 1:
The patent replaces the mechanical washing and antibody treatment process with a chemical detection method. The second pulse label (EdU) is detected through click chemistry or Staudinger ligation, which are chemical reactions that directly label the incorporated nucleoside analog without requiring physical washing or antibody incubation steps.
Solution Approach 2:
The patent changes the detection parameter from antibody binding (requiring washing) to bioorthogonal chemical reactions (click chemistry or Staudinger ligation). This parameter change allows the second label to be detected through chemical specificity rather than physical separation, eliminating the need for disruptive wash steps while maintaining detection accuracy.
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
Enables accurate measurement of cellular nucleic acid synthesis by eliminating the need for wash steps, providing a reliable and non-disruptive method for assessing baseline and changes in nucleic acid synthesis, compatible with high-throughput screening and applicable to cancer therapy assessment.
Implementation Method 1
the reactive unsaturated group is selected from the group consisting of an azide and a terminal alkyne, and the second reactive unsaturated group is selected from the group consisting of a terminal alkyne and an azide
Implementation Method 2
the copper(I) catalyst may consist of copper(I) ions or a copper(I) chelating moiety
Implementation Method 3
The fluorescent label may then be visualized and quantified by standard techniques, including plate assays, fluorescence microscopy, imaging, high content screening, or flow cytometry
Data Source
AI summary
The present invention provides a method for measuring cellular nascent nucleic acid synthesis by dual pulse labeling of nucleic acid. The first pulse labeling of nucleic acid with a nucleoside analog allows establishment of a baseline nucleic acid synthesis rate. Pulse labeling of the nucleic acid with a second nucleoside analog then allows measurement of any changes to nucleic acid synthesis. The nucleic acid synthesis can be measured as cell proliferation, DNA, or gene expression, RNA. This method does not require a potentially artifact-inducing intermediary wash step between pulse labels. Additionally, this method may be used to screen compounds for their affect on cellular proliferation by treating cells or an organism with the test compound simultaneous to or before treatment with a competitive nucleoside analog.