Department of Biology, Graduate School of Science, Kobe University, Nada, Kobe, Hyogo, Japan.
PLoS One. 2013;8(1):e51779. doi: 10.1371/journal.pone.0051779. Epub 2013 Jan 11.
Blowflies are economic pests of the wool industry and potential vectors for epidemics. The establishment of a pesticide-free, environmentally friendly blowfly control strategy is necessary. Blowflies must feed on meat in order to initiate the cascade of events that are involved in reproduction including juvenile hormone synthesis, vitellogenesis, and mating. During feeding blowflies regurgitate salivary lipase, which may play a role in releasing fatty acids from triglycerides that are found in food. However, long-chain fatty acids show low solubility in aqueous solutions. In order to solubilize and ingest the released hydrophobic fatty acids, the blowflies must use a solubilizer.
We applied native PAGE, Edman degradation, cDNA cloning, and RT-PCR to characterize a protein that accumulated in the oral disk of the black blowfly, Phormia regina. In situ hybridization was carried out to localize the expression at the cellular level. A fluorescence competitive binding assay was used to identify potential ligands of this protein.
A protein newly identified from P. regina (PregOBP56a) belonged to the classic odorant-binding protein (OBP) family. This gene was expressed in a cluster of cells that was localized between pseudotracheae on the oral disk, which are not accessory cells of the taste peg chemosensory sensilla that normally synthesize OBPs. At pH 7 and pH 6, PregOBP56a bound palmitic, stearic, oleic, and linoleic acids, that are mainly found in chicken meat. The binding affinity of PregOBP56a decreased at pH 5. We propose that PregOBP56a is a protein that solubilizes fatty acids during feeding and subsequently helps to deliver the fatty acids to the midgut where it may help in the process of reproduction. As such, PregOBP56a is a potential molecular target for controlling the blowfly.
家蝇是羊毛工业的经济害虫，也是流行病的潜在传播媒介。建立一种无农药、环保的家蝇控制策略是必要的。家蝇必须以肉为食，才能引发与繁殖有关的一系列事件，包括保幼激素合成、卵黄生成和交配。在进食过程中，家蝇会反刍唾液脂肪酶，这种酶可能在从食物中发现的甘油三酯中释放脂肪酸方面发挥作用。然而，长链脂肪酸在水溶液中的溶解度较低。为了溶解和摄取释放的疏水性脂肪酸，家蝇必须使用一种增溶剂。
我们应用天然 PAGE、Edman 降解、cDNA 克隆和 RT-PCR 来表征黑蝇 Phormia regina 口腔盘内积累的一种蛋白质。通过原位杂交在细胞水平上进行表达定位。荧光竞争结合测定用于鉴定该蛋白质的潜在配体。
从 Phormia regina（PregOBP56a）新鉴定的一种蛋白质属于经典气味结合蛋白（OBP）家族。该基因在口腔盘上假气管之间的一组细胞中表达，这些细胞不是通常合成 OBP 的味觉刺化学感觉感器的辅助细胞。在 pH 值为 7 和 pH 值为 6 时，PregOBP56a 结合棕榈酸、硬脂酸、油酸和亚油酸，这些酸主要存在于鸡肉中。在 pH 值为 5 时，PregOBP56a 的结合亲和力降低。我们提出，PregOBP56a 是一种在进食过程中溶解脂肪酸的蛋白质，随后有助于将脂肪酸输送到中肠，在那里它可能有助于繁殖过程。因此，PregOBP56a 是控制家蝇的潜在分子靶标。
