Institute of Ecology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
Department of Informatics, Institute of Computational Science, University of Italian Switzerland, Lugano, Switzerland.
Sci Rep. 2017 Mar 3;7:43770. doi: 10.1038/srep43770.
Chemoreception is essential for survival. Some chemicals signal the presence of nutrients or toxins, others the proximity of mating partners, competitors, or predators. Chemical signal transduction has therefore been studied in multiple organisms. In Drosophila species, a number of odorant receptor genes and various other types of chemoreceptors were found. Three main gene families encode for membrane receptors and one for globular proteins that shuttle compounds with different degrees of affinity and specificity towards receptors. By sequencing the genome of Drosophila nigrosparsa, a habitat specialist restricted to montane/alpine environment, and combining genomics and structural biology techniques, we characterised odorant, gustatory, ionotropic receptors and odorant binding proteins, annotating 189 loci and modelling the protein structure of two ionotropic receptors and one odorant binding protein. We hypothesise that the D. nigrosparsa genome experienced gene loss and various evolutionary pressures (diversifying positive selection, relaxation, and pseudogenisation), as well as structural modification in the geometry and electrostatic potential of the two ionotropic receptor binding sites. We discuss possible trajectories in chemosensory adaptation processes, possibly enhancing compound affinity and mediating the evolution of more specialized food, and a fine-tuned mechanism of adaptation.
化学感受对于生存至关重要。有些化学物质可以传递营养物质或毒素的存在信息，还有一些化学物质则可以传递交配对象、竞争对手或捕食者的接近信息。因此，许多生物的化学信号转导过程都得到了研究。在果蝇属中，发现了许多嗅觉受体基因和各种其他类型的化学感受器。三个主要的基因家族编码膜受体，一个基因家族编码球状蛋白，这些蛋白可以将不同亲和力和特异性的化合物转运到受体上。通过对仅限于山地/高山环境的栖息地专化种黑腹果蝇（Drosophila nigrosparsa）的基因组进行测序，并结合基因组学和结构生物学技术，我们对气味、味觉、离子型受体和气味结合蛋白进行了表征，注释了 189 个基因座，并对两个离子型受体和一个气味结合蛋白的蛋白质结构进行了建模。我们假设，黑腹果蝇的基因组经历了基因丢失和各种进化压力（多样化正选择、松弛和假基因化），以及两个离子型受体结合位点的几何形状和静电势的结构修饰。我们讨论了化学感受适应过程中可能的轨迹，这些轨迹可能增强了化合物的亲和力，并介导了更专门化的食物的进化和精细的适应机制。
