Temporal and spatial expression of homeotic genes is important for segment-specific neuroblast 6-4 lineage formation in Drosophila.
Different proliferation of neuroblast 6-4 (NB6-4) in the thorax and abdomen produces segmental specific expression pattern of several neuroblast marker genes. NB6-4 is divided to form four medialmost cell body glia (MM-CBG) per segment in thorax and two MM-CBG per segment in abdomen. As homeotic genes determine the identities of embryonic segments along theA/P axis, we investigated if temporal and specific expression of homeotic genes affects MM-CBG patterns in thorax and abdomen. A Ubx loss-of-function mutation was found to hardly affect MM-CBG formation, whereas abd-A and Abd-B caused the transformation of abdominal MM-CBG to their thoracic counterparts. On the other hand, gain-of-function mutants of Ubx, abd-A and Abd-B genes reduced the number of thoracic MM-CBG, indicating that thoracic MM-CBG resembled abdominal MM-CBG. However, mutations in Polycomb group (PcG) genes, which are negative transregulators of homeotic genes, did not cause the thoracic to abdominal MM-CBG pattern transformation although the number of MM-CBG in a few per-cent of embryos were partially reduced or abnormally patterned. Our results indicate that temporal and spa-tial expression of the homeotic genes is important to determine segmental-specificity of NB6-4 daughter cells along the anterior-posterior (A/P) axis.
Kang
Sun-Young
SY
Department of Biology Education, Seoul National University, Seoul 151-748, Korea.
Kim
Su-Na
SN
Kim
Sang Hee
SH
Jeon
Sang-Hak
SH
D000005:Abdomen / Q000196:embryology; D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis / Q000235:genetics; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D013900:Thoracic Nerves / Q000166:cytology; D013909:Thorax / Q000196:embryology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
C062393:Abd-B proteins, Drosophila; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; C066770:Pc protein, Drosophila; D014157:Transcription Factors; C066177:Ubx protein, Drosophila; C066591:abd-A protein, Drosophila; D063150:Polycomb Repressive Complex 1