Drosophila mode of metamerization in the embryogenesis of the lepidopteran insect Manduca sexta.
Insect embryos have been classified as intermediate- and short-germ embryos, in which posterior segments are thought to be generated sequentially from an uncommitted growth zone, or as long-term embryos, such as Drosophila melanogaster, which develop primordia for all segments simultaneously. In Drosophila the coordinated activities among a three-tiered cascade of zygotic segmentation genes subdivide the embryo into progressively smaller units along the anterior-posterior axis. The mode of pattern specification in lepidopteran embryos has not been determined, although on morphological grounds they have been characterized as intermediate-germ insects. We have cloned orthologues of Drosophila segmentation genes from the tobacco hawkmoth Manduca sexta and have found that the blastoderm expression patterns of these genes show a molecular prepatterning typical of Drosophila. Thus, successive segment formation in Manduca embryos may not be due to sequential addition but rather may be the consequence of a lateral compression of the embryo proceeding in an anterior-to-posterior progression. These data challenge the view that the classification of insect development according to morphological criteria can serve as a reliable indicator of the molecular mechanisms underlying segmentation.
Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Entwicklungsbiologie, Göttingen, Germany.
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001756:Blastoderm / Q000502:physiology; D017931:DNA Primers; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000196:embryology* / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005314:Embryonic and Fetal Development; D017344:Genes, Insect; D017403:In Situ Hybridization; D007605:Juvenile Hormones / Q000235:genetics; D051741:Kruppel-Like Transcription Factors; D008969:Molecular Sequence Data; D009036:Moths / Q000196:embryology* / Q000235:genetics; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012097:Repressor Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics; D051155:Wnt1 Protein
D017931:DNA Primers; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D007605:Juvenile Hormones; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D051155:Wnt1 Protein; C061245:hb protein, Drosophila; C080833:run protein, Drosophila; C074622:wg protein, Drosophila