The DNA puff 4C expresses a salivary secretion protein in Trichosia pubescens (Diptera; Sciaridae)

Abstract

DNA puffs are genomic regions of polytene chromosomes that undergo developmentally controlled DNA amplification and transcription in salivary glands of sciarid flies. Here, we tested the hypothesis that DNA puff genes code for salivary proteins in Trichosia pubescens. To do that, we generated antibodies against saliva and immunoscreened a cDNA library made from salivary glands. We isolated clones corresponding to DNA puff regions, including clone D-50 that contained the entire coding sequence of the previously isolated C4B1 gene from puff 4C. Indeed, we showed that puff 4C is a DNA puff region detecting its local transcription and its extra rounds of DNA incorporation compared to neighboring regions. We further confirmed D-50 clone identity in Western blots reacted with the anti-saliva anitiserum. We detected a recombinant protein expressed by this clone that had the expected size for a full-length product of the gene. We end with a discussion of the relationship between DNA puff genes and their products.

Beyond DNA puffs: What can we learn from studying sciarids?

“…These studies led to the suggestion that DNA amplification was a mechanism that could rapidly provide high amounts of salivary gland proteins to build the cocoon in which the larvae pupariates. Indeed, most of the identified DNA puff proteins constitute secretion polypeptides present in salivary gland (de Almeida, ; Laicine et al ., ; Winter et al ., ) and studies employing polyclonal antibodies raised against different DNA puff proteins confirmed that DNA puff proteins are present in the saliva (Andrioli et al ., ; Fontes et al ., ; Monesi et al ., ).…”

“…DNA puff formation is temporally correlated with the abundant expression of DNA puff genes (Andrioli et al ., ; Fontes et al ., ; Frydman et al ., ; Paçó‐Larson et al ., ; Penalva et al ., ; Santelli et al ., ; Wu et al ., ). Several studies, both in vivo and in vitro have revealed that the hormone ecdysone regulates DNA puff gene expression (reviewed in Monesi et al ., ).…”