Homoeosis in Drosophila: The Lethal Syndrome of the Regulator of bithorax (or trithorax) Locus and Its Interaction with Other Homoeotic Loci

AUTOR(ES)
RESUMO

Regulator of bithorax (Rg-bx)- [or trithorax (trx)-] lethal zygotes show anterior transformations of various cuticular features of the larval thorax and abdomen. The Rg-bx- lethal syndrome depends on the dosage of the bithorax gene complex (BX-C), and lack of Rg-bx+ function is antagonistic to posterior transformations displayed by Polycomb ( Pc)- embryos. Significantly, when the BX-C is deleted, the Rg-bx- embryos disclose homoeosis of mesothoracic to prothoracic cuticular structures. This homoeotic transformation is due to a reduction in Antennapedia (Antp)+ gene activity and is consequently dependent on the dosage of the Antennapedia gene complex (ANT-C), suggesting that the Rg-bx+ activity is necessary for proper expression of the Antp+ gene. However, the functional relationship between the Rg-bx and Sex combs reduced (Scr) loci in embryogenesis is still to be established.

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