COI Barcoding
Definition
DNA-based species identification using a standard 658 bp segment of the mitochondrial cytochrome oxidase subunit I gene. Sequences are matched against reference databases such as BOLD (Barcode of Life Data System) or GenBank. Allows species determination from eggs, larvae, or degraded adult material.
- DNA region
- Cytochrome c oxidase subunit I (mitochondrial), 658 base pairs
- Reference database
- BOLD (Barcode of Life Data System)
- Primary forensic use
- Species identification of insects, fish, and crustaceans when morphology is uncertain
Common questions
What is COI barcoding used for in forensics?+
COI barcoding identifies animal species by sequencing a specific 658-base-pair region of the mitochondrial cytochrome c oxidase subunit I gene. It is especially valuable in wildlife cases and forensic entomology when morphological identification (looking at body structure) is uncertain or unreliable. The technique works well for fish, crustaceans, insects, and flies.
Why is COI the standard barcode for animals?+
COI is the reference gene in the BOLD database (Barcode of Life Data System), a repository of DNA sequences for known species. This standardization means forensic labs can reliably compare unknown samples against sequences from a wide range of species.
When would a forensic entomologist use COI barcoding?+
When blowflies, beetles, or other insects collected from a crime scene need species confirmation beyond visual inspection. Precise species ID is critical for estimating the post-mortem interval, so COI DNA analysis removes guesswork when morphology alone is not definitive.
Related terms
- Accumulated Degree Hours (ADH)
- A temperature-corrected measure of developmental time. Calculated by summing (hourly ambient temperature minus the species-specific base temperature threshold) across the period of...
- Anti-Human Serum
- Antibodies raised in a rabbit (or goat) by repeated injection of human serum. The rabbit's immune system makes IgG against human serum...
- Antigen-Antibody Reaction
- The specific non-covalent binding between an antigen (a molecule capable of eliciting an immune response) and the antibody produced against it. In...
- Blood Meal
- Blood ingested by a haematophagous insect during feeding on a vertebrate host. The host's DNA persists in the insect's gut for hours...
- Calliphoridae
- The blowfly family: metallic-coloured flies that are typically the earliest colonisers of exposed remains. Forensically important genera include Calliphora, Lucilia, Chrysomya, and...
- CCMB LaCONES
- Laboratory for the Conservation of Endangered Species at the Centre for Cellular and Molecular Biology, Hyderabad. CSIR institute that handles DNA-based species...
- CITES Appendices I/II/III
- Convention on International Trade in Endangered Species. Appendix I: no commercial international trade (tiger, Indian rhino). Appendix II: trade regulated by permit....
- Cyt-B Barcoding
- PCR amplification and sequencing of the mitochondrial cytochrome-b gene. The standard marker for species identification of mammals from skin, hair, bone or...
- Cyt-B PCR
- Amplification and sequencing of the mitochondrial cytochrome-b gene. The reference marker for species identification in degraded and trace samples.
- Gut Content Extraction
- Physical dissection of a larva to remove the crop and midgut contents, which are then extracted separately from the larval carcass. The...
- Haematophagous Insect
- An insect that feeds on the blood of a vertebrate host. Examples include mosquitoes (Culicidae), sand flies (Phlebotomus, Lutzomyia), and certain midges...
- Immunoelectrophoresis
- A two-step technique: proteins are first separated by electrophoresis in agar gel, then antiserum diffuses from a parallel trough and forms precipitin...
Explained in these topics
- Determination of Species of Origin from Blood and Body FluidsCytochrome c oxidase subunit I gene sequencing, the standard DNA barcode for animals under the BOLD database. The dominant tool for wildlife species ID.
- Entomological Evidence and Post-Mortem Interval EstimationDNA-based species identification using a standard 658 bp segment of the mitochondrial cytochrome oxidase subunit I gene. Sequences are matched against referenc...
- Insects as Alternate Samples for Toxicology and DNADNA barcoding using a standardised 658-base-pair region of the mitochondrial cytochrome oxidase subunit I gene, used for species-level identification of insect...
- Wildlife Forensics in India: Wildlife Protection Act 1972, Scope and EvidenceCytochrome-c oxidase subunit I gene barcoding. The standard marker for species identification of fish, crustaceans and insects (the BOLD database reference gen...