Evolution of neuroblast identity: seven-up and prospero expression reveal homologous and divergent neuroblast fates in Drosophila and Schistocerca.
In the Drosophila CNS, early neuroblast formation and fate are controlled by the pair-rule class of segmentation genes. The distantly related Schistocerca (grasshopper) embryo has a similar arrangement of neuroblasts, despite lack of known pair-rule gene function. Does divergent pair-rule gene function lead to different neuroblast identities, or can different patterning mechanisms produce homologous neuroblasts? We use four molecular markers to compare Drosophila and Schistocerca neuroblast identity: seven-up, prospero, engrailed, and fushi-tarazu/Dax. In both insects some early-forming neuroblasts share key features of neuroblast identity (position, time of formation, and temporally accurate gene expression); thus, different patterning mechanisms can generate similar neuroblast fates. In contrast, several later-forming neuroblasts show species-specific differences in position and/or gene expression; these neuroblast identities seem to have diverged, suggesting that evolution of the insect central nervous system can occur through changes in embryonic neuroblast identity.
Broadus
J
J
Howard Hughes Medical Institute, Department of Cell and Structural Biology, University of Illinois, Urbana 61801, USA.
Doe
C Q
CQ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002454:Cell Differentiation / Q000235:genetics; D002490:Central Nervous System / Q000196:embryology*; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D004330:Drosophila / Q000196:embryology* / Q000235:genetics*; D029721:Drosophila Proteins; D015870:Gene Expression; D005819:Genetic Markers; D006110:Grasshoppers / Q000196:embryology* / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology*; D011987:Receptors, Steroid / Q000502:physiology*; D016415:Sequence Alignment; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005819:Genetic Markers; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011987:Receptors, Steroid; D014157:Transcription Factors; C073099:pros protein, Drosophila; C094295:svp protein, Drosophila