02243nas a2200157   4500008004100000245004500041210004100086260000800127300001200135490000800147520181700155100002001972700002001992700002402012856004902036       2009                        eng d00aThe occurrence of hemocyanin in Hexapoda0 aoccurrence of hemocyanin in Hexapoda  cApr  a1930-410 v2763 aHemocyanins are copper-containing, respiratory proteins that have been thoroughly studied in various arthropod subphyla. Specific O(2)-transport proteins have long been considered unnecessary in Hexapoda (including Insecta), which acquire O(2) via an elaborate tracheal system. However, we recently identified a functional hemocyanin in the stonefly Perla marginata (Plecoptera) and in the firebrat Thermobia domestica (Zygentoma). We used RT-PCR and RACE experiments to study the presence of hemocyanin in a broad range of ametabolous and hemimetabolous hexapod taxa. We obtained a total of 12 full-length and 5 partial cDNA sequences of hemocyanins from representatives of Collembola, Archeognatha, Dermaptera, Orthoptera, Phasmatodea, Mantodea, Isoptera and Blattaria. No hemocyanin could be identified in Protura, Diplura, Ephemeroptera, Odonata, or in the Eumetabola (Holometabola + Hemiptera). It is not currently known why hemocyanin has been lost in some taxa. Hexapod hemocyanins usually consist of two distinct subunit types. Whereas type 1 subunits may represent the central building block, type 2 subunits may be absent in some species. Phylogenetic analyses support the Pancrustacea hypothesis and show that type 1 and type 2 subunits diverged before the emergence of the Hexapoda. The copperless insect storage hexamerins evolved from hemocyanin type 1 subunits, with Machilis germanica (Archeognatha) hemocyanin being a possible 'intermediate'. The evolution of hemocyanin subunits follows the widely accepted phylogeny of the Hexapoda and provides strong evidence for the monophyly of the Polyneoptera (Plecoptera, Dermaptera, Orthoptera, Phasmatodea, Mantodea, Isoptera, Blattaria) and the Dictyoptera (Mantodea, Isoptera, Blattaria). The Blattaria are paraphyletic with respect to the termites.1 aPick, Christian1 aSchneuer, Marco1 aBurmester, Thorsten  uhttps://worldodonata.myspecies.info/node/210