University of Hohenheim, Institute of Physiology (230), Stuttgart, Germany.
Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Jena, Germany.
Int J Biol Sci. 2017 Jul 15;13(7):911-922. doi: 10.7150/ijbs.18402. eCollection 2017.
Under given environmental conditions, the desert locust () forms destructive migratory swarms of billions of animals, leading to enormous crop losses in invaded regions. Swarm formation requires massive reproduction as well as aggregation of the animals. Pheromones that are detected via the olfactory system have been reported to control both reproductive and aggregation behavior. However, the molecular basis of pheromone detection in the antennae of is unknown. As an initial step to disclose pheromone receptors, we sequenced the antennal transcriptome of the desert locust. By subsequent bioinformatical approaches, 119 distinct nucleotide sequences encoding candidate odorant receptors (ORs) were identified. Phylogenetic analyses employing the identified ORs from (SgreORs) and OR sequences from the related species revealed a group of locust ORs positioned close to the root, i.e. at a basal site in a phylogenetic tree. Within this particular OR group (termed basal or b-OR group), the locust OR sequences were strictly orthologous, a trait reminiscent of pheromone receptors from lepidopteran species. In situ hybridization experiments with antennal tissue demonstrated expression of b-OR types from in olfactory sensory neurons (OSNs) of either sensilla trichodea or sensilla basiconica, both of which have been reported to respond to pheromonal substances. More importantly, two-color fluorescent in situ hybridization experiments showed that most b-OR types were expressed in cells co-expressing the "sensory neuron membrane protein 1" (SNMP1), a marker indicative of pheromone-sensitive OSNs in insects. Analyzing the expression of a larger number of SgreOR types outside the b-OR group revealed that only a few of them were co-expressed with SNMP1. In summary, we have identified several candidate pheromone receptors from that could mediate responses to pheromones implicated in controlling reproduction and aggregation behavior.
在给定的环境条件下，沙漠蝗（）形成数十亿动物的破坏性迁徙群，导致入侵地区的作物大量损失。群体形成需要大量繁殖和动物聚集。已经报道说，通过嗅觉系统检测到的信息素控制着生殖和聚集行为。然而，的触角中信息素检测的分子基础尚不清楚。作为揭示信息素受体的初始步骤，我们对沙漠蝗的触角转录组进行了测序。通过随后的生物信息学方法，鉴定了 119 个编码候选气味受体（OR）的不同核苷酸序列。利用从（SgreORs）和相关物种中鉴定出的 OR 序列进行系统发育分析表明，一组蝗虫 OR 位于接近根部的位置，即在系统发育树的基部位置。在这个特定的 OR 组（称为基础或 b-OR 组）中，蝗虫 OR 序列是严格的直系同源，这一特征类似于鳞翅目物种的信息素受体。用触角组织进行的原位杂交实验表明，b-OR 类型在嗅觉感觉神经元（OSNs）中表达，这些 OSNs 要么存在于毛状感器（sensilla trichodea）中，要么存在于锥形感器（sensilla basiconica）中，这两种感受器都被报道对信息素物质有反应。更重要的是，双色荧光原位杂交实验表明，大多数 b-OR 类型在与“感觉神经元膜蛋白 1”（SNMP1）共表达的细胞中表达，SNMP1 是昆虫中指示信息素敏感 OSNs 的标志物。分析 b-OR 组之外的大量 SgreOR 类型的表达表明，只有少数与 SNMP1 共表达。总之，我们从鉴定出了几种可能介导对控制生殖和聚集行为的信息素的反应的候选信息素受体。
