Alternative transcripts expressed by small bristles, the Drosophila melanogaster nxf1 gene

The tissue-specific accumulation of small bristles (Dm nxf1) transcripts at different developmental stages of Drosophila melanogaster was analyzed by Northern blots and RT PCR. We identified four distinct transcripts: ubiquitous (3.5 kb); ovary and early embryo specific (3.3 kb); testis specific (1.9 kb and 2.8 kb) and nervous system specific (5.1 kb). The pattern of Dm nxf1 gene expression in ovaries and early embryos (0–2 h) is similar: the sizes of transcripts range from 3.0 to 3.5 kb. We propose that this size variability may reflect the different extent of cytoplasmic polyadenylation. In testes, the 2.8-kb transcript originates from alternative termination of transcription and the 1.9-kb transcript is supposed to originate from an alternative transcription start. During ontogenesis, the 5.1-kb transcript can be clearly detected in 10- to 18-h-old embryos, most prominently in the nervous ganglia of larvae, and it represents a major species in imago head extracts. We found that the 5.1-kb transcript, similarly to the nxf1 heavy transcripts in Homo sapiens and Mus musculus, results from the retention of intron 5–6 that corresponds to the intron 10–11 in Hs nxf1 and Mm nxf1 genes.