PDF(Pubmed)
Abstract：
Neonicotinoids as thiamethoxam and thiacloprid are suspected to be implicated in the decline of honey bee populations. As nicotinic acetylcholine receptor agonists, they disturb acetylcholine receptor signaling in insects, leading to neurotoxicity and are therefore globally used as insecticides. Several behavioral studies have shown links between neonicotinoid exposure of bees and adverse effects on foraging activity, homing flight performance and reproduction, but the molecular aspects underlying these effects are not well-understood. In the last years, several studies through us and others showed the effects of exposure to neonicotinoids on gene expression in the brain of honey bees. Transcripts of acetylcholine receptors, hormonal regulation, stress markers, detoxification enzymes, immune system related genes and transcripts of the energy metabolism were altered after neonicotinoid exposure. To elucidate the link between homing flight performance and shifts in gene expression in the brain of honey bees after neonicotinoid exposure, we combined homing flight activity experiments applying RFID technology and gene expression analysis. We analyzed the expression of endocrine factors, stress genes, detoxification enzymes and genes linked to energy metabolism in forager bees after homing flight experiments. Three different experiments (experiment I: pilot study; experiment II: \"worst-case\" study and experiment III: laboratory study) were performed. In a pilot study, we wanted to investigate if we could see differences in gene expression between controls and exposed bees (experiment I). This first study was followed by a so-called \"worst-case\" study (experiment II), where we investigated mainly differences in the expression of transcripts linked to energy metabolism between fast and slow returning foragers. We found a correlation between homing flight duration and the expression of cytochrome c oxidase subunit 5A, one transcript linked to oxidative phosphorylation. In the third experiment (experiment III), foragers were exposed in the laboratory to 1 ng/bee thiamethoxam and 8 ng/bee thiacloprid followed by gene expression analysis without a subsequent flight experiment. We could partially confirm the induction of cytochrome c oxidase subunit 5A, which we detected in experiment II. In addition, we analyzed the effect of the feeding mode (group feeding vs. single bee feeding) on data scattering and demonstrated that single bee feeding is superior to group feeding as it significantly reduces variability in gene expression. Based on the data, we thus hypothesize that the disruption of energy metabolism may be one reason for a prolongation of homing flight duration in neonicotinoid treated bees.
摘要：
新烟碱类如噻虫嗪和噻虫啉被怀疑与蜜蜂种群的减少有关。作为烟碱乙酰胆碱受体激动剂，它们干扰昆虫的乙酰胆碱受体信号，导致神经毒性，因此在全球范围内用作杀虫剂。一些行为研究表明，蜜蜂的新烟碱暴露与对觅食活动的不利影响之间存在联系，归巢飞行性能和再现，但是这些影响背后的分子方面还没有得到很好的理解。在过去的几年里，通过我们和其他人进行的几项研究表明，接触新烟碱对蜜蜂大脑基因表达的影响。乙酰胆碱受体转录本，荷尔蒙调节,应力标记,解毒酶，新烟碱暴露后，免疫系统相关基因和能量代谢转录本发生改变。为了阐明新烟碱暴露后蜜蜂大脑中归巢飞行性能与基因表达变化之间的联系，我们将应用RFID技术和基因表达分析的归巢飞行活动实验相结合。我们分析了内分泌因子的表达，应激基因，归巢飞行实验后，与觅食蜜蜂能量代谢相关的解毒酶和基因。进行了三个不同的实验（实验I：先导研究；实验II：“最坏情况”研究和实验III：实验室研究）。在一项试点研究中，我们想调查是否可以看到对照和暴露蜜蜂之间的基因表达差异（实验I）。第一项研究之后是所谓的“最坏情况”研究（实验II），在那里，我们主要研究了快速和慢速返回觅食者之间与能量代谢相关的转录本表达的差异。我们发现归巢飞行持续时间与细胞色素c氧化酶亚基5A的表达之间存在相关性，一个与氧化磷酸化相关的转录物。在第三个实验（实验III）中，觅食者在实验室中暴露于1ng/蜜蜂噻虫嗪和8ng/蜜蜂噻虫啉，然后进行基因表达分析，而没有随后的飞行实验。我们可以部分证实细胞色素C氧化酶5A亚基的诱导，我们在实验II中检测到的。此外,我们分析了喂养方式的影响(组喂养与单只蜜蜂喂食）数据散射，并证明单只蜜蜂喂食优于组喂食，因为它显着降低了基因表达的变异性。根据数据,因此，我们假设能量代谢的中断可能是新烟碱类治疗蜜蜂归巢飞行持续时间延长的原因之一。
