[Recovery of genomic regions affecting lawc/Trf2 expression during Drosophila melanogaster development]

Leg-arista-wing complex (lawc) mutations affect the expression of D. melanogaster proteins homologous to a human basic transcription factor, TBP (TATA-box binding protein) Related Factor 2 (TRF2), specifically involved in development. The paper for the first time reports the application of genetic screens for various genomic regions to recover genetic interactions between the lawc/Trf2 gene and other genes and genetic loci by using Deficiency Kit lines with small deletions in total providing maximal coverage of the genome. The deletion mapping allowed us to recover 26 genomic regions that, when deleted, are lethal or modify the mutant phenotype due to a decreased TRF2 expression level. These deletions could be useful in identifying both novel TRF2 targets and its positive and negative regulators. There is evidence that TRF2 can be a component of high molecular DNA Replication-related Element Factor (DREF)- and Nucleosome Remodeling Factor (NURF)-containing complexes. The present study for the first time reports new genetic interactions of lawc/Trf2 with genes that encode basic and specific transcription factors. In most cases, if mutated, those genes caused developmental defects or death of progeny. However, in the case of the e(y) 1 gene, coding for the Taf9 transcription factor, only the male reproductive system is impaired when the lawc/Trf2 phenotype is associated with a e(y)l gene mutation. Mutant lawc(p1)e(y)1(u1) males become infertile due to primary spermatocyte maturation arrest and impaired premeiotic chromosome condensation in germ cells.