Borrelia burgdorferi 2026-11-05
Borrelia burgdorferi is a spirochaete bacterium associated with Lyme disease and transmission through ticks. It is one member of a broader collection of related Lyme-associated organisms; identifying this species does not mean that every case worldwide has the same bacterial cause.
Its genome organization is unusual enough to make a useful molecular example: naturally occurring plasmids include both linear and circular forms. [ref]
Conservation of plasmid maintenance functions between linear and circular plasmids in Borrelia burgdorferi by Philip E. Stewart and others. 2003, abstract opening: natural linear and circular plasmids
Thus the word plasmid does not require circular geometry. Maintaining an extra replicating DNA molecule requires functions for inheritance as well as replication, and similarity of those functions need not imply identical overall topology. George Chaconas Created 2026-10-18 Updated 2026-11-05
George Chaconas coauthored research on maintenance functions of linear and circular plasmids in Borrelia burgdorferi. The two DNA topologies raise related questions about replication and stable inheritance.
A plasmid's shape and its maintenance machinery are distinct properties. Comparing the two forms helps ask which functions are shared and which depend on topology.[ref]
A biochemist.[ref]
https://profiles.ucalgary.ca/george-chaconas. Institutional or professional-society biography, identity and research specialization
Patricia Rosa Created 2026-10-18 Updated 2026-11-05
Geneticist studying bacterial genome maintenance. Patricia Rosa coauthored research comparing maintenance functions of linear and circular plasmids in Borrelia burgdorferi, connecting unusual genome architecture with inheritance of extrachromosomal DNA.[ref]
Philip E. Stewart Created 2026-10-18 Updated 2026-11-05
Microbiologist studying bacterial genome maintenance. Stewart and collaborators compared maintenance functions of linear and circular plasmids in Borrelia burgdorferi, testing how different DNA structures can share inheritance mechanisms.[ref]
Plasmid Created 2026-10-13 Updated 2026-10-20
A plasmid is an extrachromosomal DNA replicon: genetic material maintained by DNA replication separately from the host's main chromosomes. Separate copying does not mean independence of the host's enzymes or resources. Many plasmids are circular, but naturally occurring linear plasmids also exist.[ref]
Conservation of plasmid maintenance functions between linear and circular plasmids in Borrelia burgdorferi by Philip E. Stewart and others. Stewart, Chaconas and Rosa (2003), abstract opening sentence: natural linear and circular plasmids
Engineered plasmids can carry genes for genetic transformation and functional complementation. Typical laboratory plasmids combine an origin of replication, a selectable marker and a plasmid insert. These are engineering roles, not requirements that every natural plasmid carry an experimentally chosen selectable marker or plasmid insert.[ref]
Molecular Biology Reference by Addgene. Plasmid Elements, Figure 2 and table: origin, antibiotic-resistance gene, insert and promoter; description applies to engineered vectors
The useful separation is between keeping a DNA fragment, finding its carriers and testing its function. Molecular cloning uses propagation to recover more copies for study. Plasmid restriction mapping tests a proposed arrangement, while DNA sequencing examines its letters. A successful genetic transformation or a biological colony showing antibiotic resistance answers neither question completely. The yeast cross-species complementation experiment goes a step further by separating plasmid selection from a test of functional complementation.