Cytochrome B (Cyt B)
Definition
A mitochondrial protein-coding gene widely used in forensic species identification before COI barcoding was standardised. Still used because its reference database for vertebrates is extensive and well-curated. Short-amplicon cyt b assays target fragments under 200 base pairs for use with degraded samples.
- Gene location
- Mitochondrial genome, protein-coding
- Typical amplicon
- Under 200 bp for degraded samples
- Predecessor to
- COI barcoding as species ID marker
- Copy number
- High per cell, aids low-template recovery
Common questions
Why is cyt b still used when COI barcoding exists?+
Its vertebrate reference database is older and more extensive for many groups, and short-amplicon cyt b assays recover usable sequence from degraded casework samples such as bushmeat or processed wildlife products where COI primers may fail.
Can cyt b distinguish very closely related species?+
Resolution varies by taxon. It works well for most vertebrate genera but can struggle with recently diverged species pairs, so results are usually reported alongside the reference database match confidence rather than as an absolute identification.
Related terms
- DNA Barcoding
- Species identification using a short, standardised region of the mitochondrial genome. For animals, the primary barcode marker is a 648-base-pair segment of...
- 16S rRNA
- The small-subunit ribosomal RNA gene in bacteria (~1,550 bp). The V3-V4 hypervariable region (~470 bp) is amplified with universal bacterial primers for...
- BOLD
- Barcode of Life Data System, an international curated database linking COI sequences to verified voucher specimens with collection locality and taxonomic annotation....
- BOLD (Barcode of Life Data System)
- A curated online reference database of barcode sequences maintained by the University of Guelph, Canada. Each entry includes a voucher specimen, taxonomic...
- BOLD Systems
- Barcode of Life Data System (University of Guelph, Canada). Holds over 9 million COI reference barcodes linked to voucher specimens, with mandatory...
- Chain of Custody
- The documented chronological record of who collected, handled, transferred, and examined a piece of evidence. For digital evidence, chain of custody includes...
- CITES
- The Convention on International Trade in Endangered Species of Wild Fauna and Flora, a multilateral treaty signed in 1973 now with over...
- CITES Appendix
- CITES classifies listed species into three appendices. Appendix I prohibits commercial trade; Appendix II permits trade only with documented permits and quota...
- COI (COX1)
- Cytochrome-c oxidase subunit I gene. The 658-base-pair Folmer fragment is the globally adopted barcode-of-life marker for animals, curated in BOLD Systems and...
- COI (Cytochrome C Oxidase I)
- A mitochondrial gene encoding subunit I of the respiratory enzyme cytochrome c oxidase. Its intermediate evolutionary rate makes it the primary barcode...
- COI (Cytochrome Oxidase Subunit I)
- The primary barcode gene for the animal kingdom under the Barcode of Life initiative. A 648-bp region within the COI gene is...
- ITS Region
- Internal transcribed spacer region, flanking the 5.8S rRNA gene between the 18S and 28S subunits in fungi and plants. The ITS1-5.8S-ITS2 fragment...
Explained in these topics
- Molecular Identification of Forensically Important InsectsA second mitochondrial barcode gene used as a complement or backup to COI, particularly when COI primers fail on degraded samples or when taxa-specific seconda...
- Non-Human DNA and Species IdentificationA protein-coding gene in the mitochondrial genome used widely for vertebrate species identification. Its moderate mutation rate resolves most closely related s...
- Species Identification by Cytochrome-b, COI Barcoding and 16S rRNAA gene on the mitochondrial genome encoding a component of the electron transport chain. Its 350-400 bp diagnostic fragment is the standard molecular marker fo...
- Wildlife Crime and Biological Evidence