title: Specification of neural precursor identity in the geophilomorph centipede Strigamia maritima.
abstract: Despite differences in the formation of neural precursors, all arthropod species analyzed so far generate about 30 single precursors (insects/crustaceans) or precursor groups (chelicerates/myriapods) per hemi-segment. In Drosophila, each precursor has a distinct identity conferred by segment polarity and dorso-ventral patterning genes that subdivide the ventral neuroectoderm into a grid-like structure. Temporal patterning mechanisms generate additional diversity after delamination from the neuroectoderm. Previous work shows that the genetic network involved in recruitment and specification of neural precursors is conserved in arthropods. However, comparative studies on generation of precursor diversity are few and partial. Here, we test whether aspects of the Drosophila model may apply in the geophilomorph centipede Strigamia maritima. We describe precursor formation, based on morphology and on Delta and Notch expression. We then show that in S. maritima, hunchback and Krüppel are expressed in subsets of neural precursors generating distinct temporal expression domains within the plane of the neuroectoderm. This expression pattern suggests that temporal changes in spatial patterning cues may result in the ordered production of different neural identities. We suggest that temporal patterning mechanisms were present in the last common ancestor of arthropods, although the regulatory interactions of transcription factors might have diverged in the lineage leading to insects.
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
authors.forename: Ariel D
authors.initials: AD
authors.lastname: Chipman
authors.forename: Angelika
authors.initials: A
authors.lastname: Stollewerk
mesh_terms: D000818:Animals; D001181:Arthropods / Q000196:embryology* / Q000378:metabolism; D019521:Body Patterning; D019070:Cell Lineage; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism; D004475:Ectoderm / Q000378:metabolism; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D009474:Neurons / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D051741:Kruppel-Like Transcription Factors; D008565:Membrane Proteins; D051880:Receptors, Notch; D014157:Transcription Factors; C064045:delta protein; C080774:erythroid Kruppel-like factor; C061245:hb protein, Drosophila; D012313:RNA