RESUMO
We have mapped the only transcription unit known to be present in the C-8 DNA puff of Rhynchosciara americana and describe the isolation and sequence of a cDNA clone, pRa C-8-22, which contains a nearly complete copy of the mRNA transcribed from this DNA puff and part of the sequence of genomic clone BSC8-0.9, which contains the promotor region and the remainder of the transcription unit. The characteristics of the protein predicted from the ORF present in the cDNA indicate that it is unique and secreted.
Assuntos
DNA/genética , Dípteros/genética , Proteínas de Insetos , Proteínas e Peptídeos Salivares/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Dados de Sequência Molecular , Proteínas e Peptídeos Salivares/metabolismo , Transcrição GênicaRESUMO
The synchronous development of a sibling group of Rhynchosciara larvae enables us to follow the relationship between the local transcription and extrareplication of C3 and C8 DNA puffs. Although DNA amplification at these two loci takes place during the last cycle of DNA duplication in salivary gland chromosomes, a different timing of puff expression was observed for the two regions analysed. C3 puff transcription is a late event in relation to the C8 counterpart. We present evidence that this might be a consequence of the different firing of DNA amplification in both loci. No signs of DNA rearrangements were detected with probes that extend the previously analysed regions.