Ralf Janssen


Affiliation: Uppsala University
Country: Sweden


  1. Janssen R, Eriksson B, Tait N, Budd G. Onychophoran Hox genes and the evolution of arthropod Hox gene expression. Front Zool. 2014;11:22 pubmed publisher
    ..Reconstruction of the ancestral arthropod Hox pattern and comparison with the patterns in the different arthropod classes reveals phylogenetic support for Mandibulata and Tetraconata, but not Myriochelata and Atelocerata. ..
  2. Janssen R, Budd G. Deciphering the onychophoran 'segmentation gene cascade': Gene expression reveals limited involvement of pair rule gene orthologs in segmentation, but a highly conserved segment polarity gene network. Dev Biol. 2013;382:224-34 pubmed publisher
    ..This may suggest that the common ancestor of lophotrochozoans and ecdysozoans was already segmented utilising the same SPG-network, or that the SPG-network was recruited independently in annelids and onychophorans/arthropods. ..
  3. Janssen R, Lionel L. Embryonic expression of a Long Toll (Loto) gene in the onychophorans Euperipatoides kanangrensis and Cephalofovea clandestina. Dev Genes Evol. 2018;228:171-178 pubmed publisher
    ..The identified gene shows sequence and expression pattern characteristics of Loto genes. However, its expression pattern also comprises some general differences to arthropod Loto genes that are involved in CE. ..
  4. Janssen R, Andersson E, Betnér E, Bijl S, Fowler W, Höök L, et al. Embryonic expression patterns and phylogenetic analysis of panarthropod sox genes: insight into nervous system development, segmentation and gonadogenesis. BMC Evol Biol. 2018;18:88 pubmed publisher
    ..The new data expand our knowledge about the expression and implied function of Sox genes to Mandibulata (Myriapoda+Pancrustacea) and Panarthropoda (Arthropoda+Onychophora). ..
  5. Janssen R, Budd G, Damen W, Prpic N. Evidence for Wg-independent tergite boundary formation in the millipede Glomeris marginata. Dev Genes Evol. 2008;218:361-70 pubmed publisher
    ..The proposed mechanism is similar to the mechanism used to establish the AP boundary in Drosophila wings and ventral pleura. ..
  6. Janssen R. A molecular view of onychophoran segmentation. Arthropod Struct Dev. 2017;46:341-353 pubmed publisher
  7. Janssen R, Budd G. Gene expression analysis reveals that Delta/Notch signalling is not involved in onychophoran segmentation. Dev Genes Evol. 2016;226:69-77 pubmed publisher
  8. Janssen R, Budd G, Prpic N, Damen W. Expression of myriapod pair rule gene orthologs. Evodevo. 2011;2:5 pubmed publisher
    ..Conserved expression patterns of PRGs in insects and myriapods, however, may represent ancestral features involved in segmenting the arthropod ancestor. ..
  9. Janssen R, Budd G. Gene expression suggests conserved aspects of Hox gene regulation in arthropods and provides additional support for monophyletic Myriapoda. Evodevo. 2010;1:4 pubmed publisher
    ..Of the two splice variants of Ubx/Antp only one could be isolated from myriapods, representing a possible further synapomorphy of the Myriapoda. ..

More Information


  1. Janssen R, Le Gouar M, Pechmann M, Poulin F, Bolognesi R, Schwager E, et al. Conservation, loss, and redeployment of Wnt ligands in protostomes: implications for understanding the evolution of segment formation. BMC Evol Biol. 2010;10:374 pubmed publisher
    ..This requires further analysis of the expression and function of these genes in a wider range of taxa...
  2. Janssen R, Damen W, Budd G. Expression of collier in the premandibular segment of myriapods: support for the traditional Atelocerata concept or a case of convergence?. BMC Evol Biol. 2011;11:50 pubmed publisher
  3. Janssen R, Damen W, Budd G. Expression of pair rule gene orthologs in the blastoderm of a myriapod: evidence for pair rule-like mechanisms?. BMC Dev Biol. 2012;12:15 pubmed publisher
    ..We discuss the possibilities that blastoderm patterning may be conserved in long-germ and short-germ arthropods, and that a posterior double segmental mechanism may be present in short-germ arthropods. ..
  4. Janssen R. Diplosegmentation in the pill millipede Glomeris marginata is the result of dorsal fusion. Evol Dev. 2011;13:477-87 pubmed publisher
    ..If the former is the case, my work may provide an impressive example of Haeckel's recapitulation theory...
  5. Janssen R, Jörgensen M, Lagebro L, Budd G. Fate and nature of the onychophoran mouth-anus furrow and its contribution to the blastopore. Proc Biol Sci. 2015;282: pubmed publisher
    ..The new data from the onychophorans thus remove one of the key pieces of evidence for the amphistomy theory. Rather, in line with other recent results, it suggests that ancestral bilaterian development was deuterostomic. ..
  6. Janssen R, Budd G. Investigation of endoderm marker-genes during gastrulation and gut-development in the velvet worm Euperipatoides kanangrensis. Dev Biol. 2017;427:155-164 pubmed publisher
  7. Janssen R, Eriksson B, Budd G, Akam M, Prpic N. Gene expression patterns in an onychophoran reveal that regionalization predates limb segmentation in pan-arthropods. Evol Dev. 2010;12:363-72 pubmed publisher
    ..The reversed hth and exd patterns in chelicerates and myriapods are therefore an apomorphy for this group, the Myriochelata, lending support to the Myriochelata and Tetraconata clades in arthropod phylogeny. ..
  8. Janssen R, Budd G, Damen W. Gene expression suggests conserved mechanisms patterning the heads of insects and myriapods. Dev Biol. 2011;357:64-72 pubmed publisher
    ..This finding implies that the anterior patterning mechanism already existed in the last common ancestor of insects and myriapods...
  9. Schwager E, Sharma P, Clarke T, Leite D, Wierschin T, Pechmann M, et al. The house spider genome reveals an ancient whole-genome duplication during arachnid evolution. BMC Biol. 2017;15:62 pubmed publisher