Related Experiment Video
Updated: Feb 16, 2026
07:24
Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
Published on: February 10, 2023
2.0K
Polymorphic duplicate genes and persistent non-coding sequences reveal heterogeneous patterns of mitochondrial DNA
Rebecca A Chong1,2, Rachel Lockridge Mueller3
1Department of Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA. rachong@hawaii.edu.
BMC Genomics
|December 29, 2017
Summary
Mitochondrial gene order diversity in salamanders arises from gene duplication and loss. Duplicate rRNA genes are lost, while duplicate tRNAs and non-coding DNA persist, challenging assumptions about genomic reduction.
Area of Science:
- Evolutionary Biology
- Genomics
- Molecular Biology
Background:
- Mitochondria are central to cellular respiration, housing the citric acid cycle and oxidative phosphorylation.
- Metazoan mitochondrial genomes are small, circular DNA molecules with conserved gene content but diverse gene orders.
- The duplication-random loss (DRL) model explains gene order diversity, but the dynamics of gene loss post-duplication are poorly understood.
Purpose of the Study:
- To investigate the tempo and mode of DNA loss following mitochondrial gene duplication events.
- To determine mitochondrial gene orders in the salamander genus Aneides.
- To analyze gene order evolution in a phylogenetic context to reveal patterns of DNA loss.
Main Methods:
- Mitochondrial gene order determination across the salamander genus Aneides.
- Phylogenetic analysis of mitochondrial gene orders.
- Comparative analysis of duplicate gene persistence and loss.
Main Results:
- Identified two distinct mitochondrial gene duplication events in Aneides, one ancient and one recent.
- Observed near-complete loss of duplicate rRNA genes post-recent duplication.
- Found persistence of duplicate protein-coding genes as pseudogenes and functional duplicate tRNAs.
- Demonstrated long-term persistence of duplicated non-coding DNA.
Conclusions:
- Selection for mitochondrial genome efficiency may not strongly disfavor extraneous sequences in salamanders.
- Duplicate rRNA genes appear potentially deleterious, leading to their elimination.
- The persistence of duplicate tRNAs and non-coding DNA suggests relaxed selection against non-functional sequences in some contexts.
Related Concept Videos
02:19Export of Mitochondrial and Chloroplast Genes
4.2K
A eukaryotic cell can have up to three different types of genetic systems: nuclear, mitochondrial, and chloroplast. During evolution, organelles have exported many genes to the nucleus; this transfer is still ongoing in some plant species. Approximately 18% of the Arabidopsis thaliana nuclear genome is thought to be derived from the chloroplast’s cyanobacterial ancestor, and around 75% of the yeast genome derived from the mitochondria’s bacterial ancestor. This export has occurred...
4.2K
02:37Gene Duplication and Divergence
8.0K
The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are...
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are...
8.0K
02:59Animal Mitochondrial Genetics
9.3K
Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
9.3K
01:57Gene Families
10.0K
Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
10.0K
02:39lncRNA - Long Non-coding RNAs
10.0K
In humans, more than 80% of the genome gets transcribed. However, only around 2% of the genome codes for proteins. The remaining part produces non-coding RNAs which includes ribosomal RNAs, transfer RNAs, telomerase RNAs, and regulatory RNAs, among other types. A large number of regulatory non-coding RNAs have been classified into two groups depending upon their length – small non-coding RNAs, such as microRNA, which are less than 200 nucleotides in length, and long non-coding RNA...
10.0K
03:21Genome Size and the Evolution of New Genes
9.2K
While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
9.2K