Showing papers by "Detlef Weigel published in 1987"

EGF homologous sequences encoded in the genome of Drosophila melanogaster, and their relation to neurogenic genes.

Abstract: The function of the neurogenic genes of Drosophila melanogaster is required for a normal pattern of commitment of neural and epidermal progenitor cells. In the course of searching for a molecular basis for the functional interrelationships that exist between the neurogenic genes, fragments of cloned DNA from the genes master mind (mam), Delta (Dl), Enhancer of split [E(spl)] and Notch (N) were hybridized to each other. Strong cross-hybridization was observed between a fragment of the Dl gene and a fragment of the N gene encoding a peptide with homology to several proteins of mammals, including the epidermal growth factor (EGF). Sequencing of this Dl fragment revealed an open reading frame encoding four EGF-like repeats with homology to the repeats found in the N gene. Screening genomic and cDNA libraries under conditions of reduced stringency with Dl and N probes that encode EGF-like repeats uncovered several cross-hybridizing clones, suggesting that other Drosophila genes may also encode such peptides. Part of a cross-hybridizing cDNA clone, derived from a gene located at position 95F on the third chromosome, was sequenced and found to encode five repeats with homology to those encoded by N and Dl. Preliminary evidence on the spatial pattern of transcription indicates that the gene at position 95F is regulated in its expression, as it is transcribed in all ectodermal derivatives, with the exception of the central nervous system. Indirect evidence suggests that this clone may derive from the crumbs (crb) gene, which is likely to be an hitherto unknown neurogenic gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular organization of master mind, a neurogenic gene of Drosophila melanogaster

Abstract: The gene master mind (mam) is located in bands 50C23-D1 of the second chromosome of Drosophila melanogaster. mam is one of the neurogenic genes, whose function is necessary for a normal segregation of neural and epidermal lineages during embryonic development. Loss of function of any of the neurogenic genes results in a mis-routeing into neurogenesis of cells that normally would have given rise to epidermis. We describe here the molecular cloning of 198 kb of genomic DNA containing the mam gene. Ten different mam mutations (point mutants and chromosomal aberrations) have been mapped within 45 kb of the genomic walk. One of the mutations, an insertion of a P-element, was originally recovered from a dysgenic cross. Four different wild-type revertants of this mutation were characterized at the molecular level and, although modifications of the insertions were found, in no case was the transposon completely excised. An unusually high number of the repetitive opa sequence, and of an additional previously unknown element, which we have called N repeat, are scattered throughout the 45 kb where the mam mutations map. The functional significance of these repeats is unknown.