Teleost Anatomy Ontology
The Teleost Anatomy Ontology (TAO) is a multi-species anatomy ontology for teleost fishes. Growth of the TAO is enabled by contributions from data curators and the ichthyological community (see Anatomy Term Trackers). The TAO can be browsed by using the NCBO BioPortal. Details about the development and use of TAO can be found in Dahdul et al. 2010
The current release may be found here.
TAO and ZFA synchronization
The TAO was initialized with terms from the ZFA, and we currently maintain manual synchronization of the two ontologies. A synchronization tool (in development) will help automate this process.
One of the challenges in synchronzing the two ontologies involves the addition of terms to the TAO that are not required for the ZFA. The addition of these terms to the TAO may require the creation of additional intermediate terms that are redundant for the ZFA. For example, zebrafish have only one type of tooth (ceratobranchial 5 tooth). Other teleost species have teeth on the jaw bones and other branchial arch and oral cavity bones. Because of this, the term ‘tooth’ is needed in the TAO as a parent to all tooth types:
- ceratobranchial 5 tooth is_a tooth
- premaxillary tooth is_a tooth
- tooth is_a multi-tissue structure
The term ‘tooth’ is redundant for the ZFA because zebrafish have only one type of tooth:
- ceratobranchial 5 tooth is_a multi-tissue structure
Term definitions are important because they facilitate consistent use of a term in annotation of disparate data types by different curators. The TAO follows the convention that each term should have a textual definition of the genus-differentia form, i.e., a subclass structure of A is an A that has properties X and Y that distinguish it from the other subclass structures of A (Smith et al. 2007).
The entity term B is defined by its membership in higher category entity A and distinguished from its sibling terms by characteristic X. Entity definitions are primarily based on structural criteria. Distinguishing characteristics (X) can include the location, shape, and a list of the parts of the entity.
The following are examples of genus-differentia definitions in the TAO:
- Antorbital: Dermal bone that is located on the anterior margin of the infraorbital series, dorsal to the first infraorbital and lateral to the nasal bone.
- Dentary: Dermal bone that forms the anterolateral part of the lower jaw.
In example 1, the definition mentions the parent dermal bone of the term antorbital, followed by the characteristics that differentiate antorbital from all other dermal bones.
Comments: Taxonomic statements to be applied to a structure, which are not universals, are recorded in the comment field for that term. For example, Weberian apparatus (TAO: 0001188 ) has the following definition: “Anatomical cluster that consists of the modified anteriormost vertebrae and associated structures that connect the swim bladder to the inner ear.,” and the following is recorded in the comment field: “Vertebra 1-4, and sometimes vertebra 5 in some catfishes, are part of the Weberian apparatus. Weberian apparatus is present in Otophysi.” Here the statements about components of the Weberian apparatus do not universally apply to all teleosts, but is included in the comment field because this information is potentially helpful to the ontology user for general understanding and for identifying structures.
Anatomy Term Tracker and Teleost-discuss Mailing List
The anatomy ontology is regulary updated to include new terms and developed based on feedback from the community. Requests for changes are submitted to the anatomy term tracker and a summary is forwarded to the teleost-discuss mailing list for community discussion (see instructions on requesting terms for details). Terms are added to the TAO usually within one week, with any comments or suggestions from teleost-discuss incorporated. We invite you to join the teleost-discuss mailing list and contribute to the discussion of terms. Archives of teleost-discuss are also available.
Homology links are important in the use of multi-species ontologies to define homology relations between different terms in the ontology, and because homology is not implied if the same term is used in annotations for different species. Terms in the anatomy ontology are defined based on structural similarity, and it cannot be assumed that this similarity is due to common ancestry. For example, zebrafish and humans both possess a frontal bone; however, there is evidence that the zebrafish frontal bone is homologous to the human parietal bone. Our use of the homologous_to relation between entities that are homologues will help clarify the identity of such similarly named but nonhomologous bones.
We have developed a method for homology designation by recording homology statements outside of the ontology, as an annotation with attribution and evidence codes. Homology statements are hypotheses, and users of our database will have the option of viewing competing hypotheses of homology when they occur.