title: Molecular characterization of the B-2 DNA puff gene of Rhynchosciara americana.
abstract: We have sequenced a 2.5-kb DNA fragment of the B-2 DNA puff from the sciarid Rhynchosciara americana and have defined its transcription unit. This puff is active during the formation of the communal cocoon, which is important for successful metamorphosis of this species and coincides with the final cycle of polytenization in its salivary glands. The B-2 polypeptide, together with the products of two other previously characterized DNA puffs, seems to be engaged in an interaction that results in a gradual modification and hardening of the cocoon structure. The B-2 messenger is temporally regulated in apparent coordination with the other puff products. The predicted polypeptide has characteristics similar to polypeptides from previously sequenced DNA puff genes, in particular those from the R. americana C-8 gene and the Bradysia hygida C-4 gene. The cloned sequence of the B-2 puff is differentially amplified in the three gland regions examined, achieving its highest amplification level of approximately fourfold (two extra cycles) in the anterior segment of the gland. The C-3 DNA puff sequence was also found to be differentially amplified in the different gland regions. Implications of the widespread presence of DNA amplification as a form of gene regulation in the Sciaridae are discussed.
authors.affiliation: Depto. Bioquímica, Instituto de Química, Universidade de São Paulo, Cidade Universitária, Av Prof Lineu Prestes, 748, CEP 05508-900, São Paulo, Brazil.
authors.forename: Roberto Vicente
authors.initials: RV
authors.lastname: Santelli
authors.forename: Fabio
authors.initials: F
authors.lastname: Siviero
authors.forename: Glaucia Maria
authors.initials: GM
authors.lastname: Machado-Santelli
authors.forename: F J S
authors.initials: FJ
authors.lastname: Lara
authors.forename: Ann Jacob
authors.initials: AJ
authors.lastname: Stocker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004175:Diptera / Q000235:genetics*; D020869:Gene Expression Profiling; D017344:Genes, Insect; D007814:Larva; D008969:Molecular Sequence Data; D012471:Salivary Proteins and Peptides / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D012471:Salivary Proteins and Peptides