Abstract
When the first group of DNA puffs is active in the salivary gland regions S1 and S3 of Bradysia hygida larvae, there is a large increase in the production and secretion of new salivary proteins demonstrable by [3H]-Leu incorporation. The present study shows that protein separation by SDS-PAGE and detection by fluorography demonstrated that these polypeptides range in molecular mass from about 23 to 100 kDa. Furthermore, these proteins were synthesized mainly in the S1 and S3 salivary gland regions where the DNA puffs C7, C5, C4 and B10 are conspicuous, while in the S2 region protein synthesis was very low. Others have shown that the extent of amplification for DNA sequences that code for mRNA in the DNA puffs C4 and B10 was about 22 and 10 times, respectively. The present data for this group of DNA puffs are consistent with the proposition that gene amplification is necessary to provide some cells with additional gene copies for the production of massive amounts of proteins within a short period of time.
Highlights
Gene amplification for protein-coding genes during development has been demonstrated in only two biological systems: the DNA puffs of Sciaridae [1] and the chorion genes in ovarian follicle cells of Drosophila [2]
In the present study we showed a strong temporal correlation between the activity of the first four DNA puffs of Bradysia hygida and a short period of about 10 h of intense secretory protein synthesis
In the present study we demonstrated an increase in the production and secretion of proteins by the salivary glands of Bradysia hygida during a short period of time, when the first group of DNA puffs is active in the S1 and S3 regions
Summary
Gene amplification for protein-coding genes during development has been demonstrated in only two biological systems: the DNA puffs of Sciaridae [1] and the chorion genes in ovarian follicle cells of Drosophila [2]. In the female-sterile Drosophila mutant ocelliless, in which two of these genes are amplified less, the corresponding mRNA and protein products accumulate at lower levels in the egg chamber. These results led Spradling and Mahowald [2] to propose that gene amplification is necessary to provide some cells with additional gene copies for the production of massive amounts of protein within a short period of time.
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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