6533b837fe1ef96bd12a27e0
RESEARCH PRODUCT
A hemocyanin from the Onychophora and the emergence of respiratory proteins
Kristina KuscheHilke RuhbergThorsten Burmestersubject
DNA ComplementaryMultidisciplinaryBase Sequencebiologymedicine.medical_treatmentMolecular Sequence DataHemocyaninAnatomyBiological Sciencesbiology.organism_classificationEpiperipatusPhylogeneticsEvolutionary biologyHemocyaninsHemolymphmedicineAnimalsRespiratory functionOnychophoraAmino Acid SequenceArthropodPeripatidaeCloning MolecularArthropodsPhylogenydescription
The velvet worms (Onychophora) are considered living fossils and are closely related to the Euarthropoda. Onychophora possess a tracheal system for respiratory function, but oxygen-transport proteins have been considered unnecessary. Here, we show that the hemolymph of the Epiperipatus sp. (Onychophora: Peripatidae) contains an arthropod-type hemocyanin, demonstrating that such protein exists outside the Euarthropoda. Thus, the evolution of oxygen carriers preceded the divergence of the Onychophora and Euarthropoda and was most likely linked to the evolution of an efficient circulatory system in a low-oxygen environment. The cDNA of the Epiperipatus hemocyanin subunit comprises 2,287 bp and encodes for a protein of 641 aa (73.6 kDa). Phylogenetic analyses of the arthropod hemocyanin sequences show that the Onychophora form a robust sister-group of the Euarthropoda, whereas the monophyly of the Tracheata is not supported.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2002-07-29 | Proceedings of the National Academy of Sciences |