Related Experiment Video
Updated: Aug 7, 2026
09:52
Genetic Manipulation in Δku80 Strains for Functional Genomic Analysis of Toxoplasma gondii
Published on: July 12, 2013
The partial 3'-conserved segment duplications in the integrons In6 from pSa and In7 from pDGO100 have a common origin
H W Stokes1, C Tomaras, Y Parsons
1School of Biological Sciences, Macquarie University, Sydney NSW.
Plasmid
|July 1, 1993
Summary
Integrons acquire genes via recombination, often conferring antibiotic resistance. Unusual integrons In6 and In7 feature duplicated sulI genes, with distinct antibiotic resistance genes (dhfrX or cat) in a second variable region.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Integrons are mobile genetic elements that capture genes through site-specific recombination.
- Antibiotic resistance genes are frequently found within the variable regions of integrons.
- Integrons In6 and In7 possess a unique duplication of the sulI gene within their 3'-conserved segment.
Purpose of the Study:
- To investigate the DNA sequence and structure of the duplicated sulI region in integrons In6 and In7.
- To identify the genes located between the two sulI copies in these unusual integrons.
- To explore the evolutionary origins of integrons with partial 3'-conserved segment duplications.
Main Methods:
- DNA sequencing of the segment between the duplicated sulI genes in In7.
- Comparative sequence analysis of the corresponding region in In6.
- Identification of antibiotic resistance genes within these regions.
Main Results:
- In In7, the segment between sulI genes is 2822 bp and contains the trimethoprim resistance gene (dhfrX).
- In In6, the corresponding 4.5 kb region is largely similar but contains a chloramphenicol resistance gene (cat) instead of dhfrX.
- This indicates a second variable region within the integron structure capable of acquiring different resistance genes.
Conclusions:
- The structural similarity of In6 and In7 suggests a common origin for their duplicated DNA segments.
- A potential mechanism for the formation of integrons with partial 3'-conserved segment duplications is proposed.
- The findings highlight the plasticity of integrons in acquiring diverse antibiotic resistance genes in novel locations.
Related Concept Videos
02:26Conservation of Protein Domains Over Different Proteins
Protein domains are small structurally independent units that are part of a single amino acid chain. Although these domains are often structurally independent, they may rely on synergistic effects to perform their functions as part of a larger protein. Protein domains may be conserved within the same organism, as well as across different organisms.
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to form...
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to form...
03:08LTR Retrotransposons
LTR retrotransposons are class I transposable elements with long terminal repeats flanking an internal coding region. These elements are less abundant in mammals compared to other class I transposable elements. About 8 percent of human genomic DNA comprises LTR retrotransposons. Some of the common examples of LTR retrotransposons are Ty elements in yeast and Copia elements in Drosophila.
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...
03:18Non-LTR Retrotransposons
As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...
02:51Multi-species Conserved Sequences
Next-generation sequencing technologies have created large genomic databases of a variety of animals and plants. Ever since the human genome project was completed, scientists studied the genome of primates, mammals, and other phylogenetically distant living beings. Such large-scale studies have provided new insights into the evolutionary relationship between organisms.
Although the genome of each species varies greatly from each other, a few sequences are highly conserved. Such conserved DNA...
Although the genome of each species varies greatly from each other, a few sequences are highly conserved. Such conserved DNA...
02:32Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...