Plasmid Frequency Tracking
Plasmid Frequency Tracking - Related Videos
08:16
Plasmid Purification
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2023
Plasmid purification is a technique used to isolate and purify plasmid DNA from genomic DNA, proteins, ribosomes, and the bacterial cell wall. A plasmid is a small, circular, double-stranded DNA that is used as a carrier of specific DNA molecules. When introduced into a host organism via transformation, a plasmid will be replicated, creating numerous copies of the DNA fragment under study. In this video, a step-by-step generalized procedure is described for how to perform plasmid purification.
01:28
Plasmids
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2025
Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...
07:11
Homemade Site Directed Mutagenesis of Whole Plasmids
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Cited by 92 •
2009
Site directed mutagenesis of whole plasmids is a simple way to create slightly different variations of an original plasmid. Here we demonstrate an easy and cost effective way to introduce base substitutions into a plasmid using standard reagents.
02:41
Amplification of a Suicide Plasmid in a Bacterial Host
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2025
Source: Tomás, J. M., et al. Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility. J. Vis. Exp. (2022).This video demonstrates the initiator-dependent amplification of a suicide plasmid in E. coli. The plasmid, which carries an antibiotic resistance gene, replicates only in the presence of an initiator protein encoded by the host. After electroporation and incubation in recovery medium, the mixture is plated on antibiotic-containing agar.
08:57
High-throughput Yeast Plasmid Overexpression Screen
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Cited by 12 •
2011
Here we describe a plasmid overexpression screen in Saccharomyces cerevisiae, using an arrayed plasmid library and a high-throughput yeast transformation protocol with a liquid handling robot.
FAQs
A stable frequency suggests that plasmid retention and loss remain relatively balanced under the tested growth conditions. A decline indicates that plasmid-negative cells are becoming more common, whereas an increase indicates greater representation of plasmid-positive cells. Comparing these patterns over defined generations helps distinguish persistent inheritance from changing population composition.
Tracking both cell classes shows whether the plasmid remains associated with most of the population or is progressively lost. Plasmid-positive cells represent retention of the genetic element, while plasmid-negative cells provide evidence of loss or failure of inheritance. Their changing proportions therefore provide a population-level measure of genetic stability rather than a single-cell observation.
The same plasmid can display different frequency patterns under different specified growth conditions. Such comparisons can reveal whether environmental or experimental conditions are associated with plasmid retention, loss, transmission, or possible fitness effects. Recording the conditions alongside each measurement is therefore essential for interpreting whether an observed frequency change reflects the plasmid system or the setting in which it was tested.
Following frequencies over time provides evidence about how plasmids persist and spread within a microbial population. A pattern consistent with continued presence across generations supports inheritance, while changes involving transmission can indicate movement of the plasmid between cells. The measurements do not merely establish whether DNA is present; they help investigate the relative roles of retention, loss, and horizontal gene transfer.
Researchers first define the generations and growth conditions to compare, then classify cells according to plasmid status using a selectable marker, an observable marker, or a molecular assay. They measure the proportions of plasmid-positive and plasmid-negative cells at the selected time points and compare those values to evaluate retention, loss, transmission, and stability.
Selectable or observable markers provide ways to distinguish cells carrying the plasmid from those that do not, while molecular assays identify plasmid status through direct measurement of molecular features. The appropriate choice depends on the experimental design and the information required. Regardless of method, the result should support comparison of plasmid-positive and plasmid-negative frequencies across defined generations.
It is useful when researchers need to evaluate the stability of engineered DNA elements in microbial populations. Measurements can show whether a plasmid-based system is retained, lost, transmitted, or associated with possible fitness effects under specified conditions. These results support experimental optimization by identifying frequency patterns that may affect the persistence of engineered genetic systems.
Repeated measurements across defined generations produce population-level data describing how plasmid-positive and plasmid-negative cells change over time. Those patterns can be compared under specified growth conditions and used to examine retention, loss, transmission, and possible fitness effects. In genetics, this evidence supports modeling plasmid behavior and evaluating how engineered DNA elements may persist within microbial populations.