Das De Tanwee, Hasija Yasha, Dixit Rajnikant
Laboratory of Host-Parasite Interaction Studies, ICMR-National Institute of Malaria Research; Department of Biotechnology, Delhi Technological University, New Delhi, India.
Department of Biotechnology, Delhi Technological University, New Delhi, India.
J Vector Borne Dis. 2018 Apr-Jun;55(2):89-97. doi: 10.4103/0972-9062.242569.
BACKGROUND & OBJECTIVES: Attractin, is a large multi-domain protein which has regulatory functions in multiple physiological processes and thus have strong therapeutic potential. In invertebrates, it was first identified as a water-borne protein pheromone that plays important role in chemical communication and coordinates reproductive activities. But its role in mosquitoes/insects remains unknown. Our unexpected discovery of attractin homolog from the olfactory tissue of Anopheles culicifacies mosquito prompted us to investigate the possible role of Ac-attractin (Ac-atrn) in diverse behavioural responses, e.g. feeding, mating and other non-genetic stresses.
A homology search analysis was performed to identify the full length attractin (Ac-atrn) gene of Anopheles culicifacies mosquito. To unravel its molecular function during external and internal stresses, extensive real-time PCR was performed in the neuro-olfactory tissues of the adult mosquitoes as well as in the larval stages. Further, a behavioural assay was conducted to elucidate its role in mosquitoes mating behaviour.
The results indicated that Ac-atrn is a 3942 bp long transcript which encodes a 1313 amino acid protein, having multiple domains including CUB, EGF, Keltch, etc, with 80-90% homology to other insect/mosquito homologs. Ac-atrn gene was dominantly expressed in the young larvae and its expression was elevated in response to the fresh food supply in the starved larvae. Cold stress temporarily arrested the expression of Ac-atrn gene. In case of adult mosquitoes, olfactory and brain tissue showed relatively higher expression of Ac-atrn than reproductive organs. Although, starvation did not yield significant changes in olfactory tissues, but aging and nutritional stress modulated Ac-atrn expression in the brain tissue. Furthermore, a circadian rhythm dependent change in the expression of Ac-atrn of virgin and mated mosquitoes (both sexes), indicates that Ac-atrn might also have a pheromone guided role during swarm formation and mating behaviour.
INTERPRETATION & CONCLUSION: The relative expression profiling of Ac-atrn gene in the larvae during nutritional and cold stress suggested its possible role in mediating chemical communication towards the food source and in thermal regulation of young larvae. Similarly, it might have crucial regulatory role in the stress management and survival of adult mosquitoes. The results revealed that Ac-atrn gene is a global regulator of many physiological processes in mosquitoes including stress response and mating behaviour and thus might be a potential target to design novel intervention strategy against mosquitoes.
吸引素是一种大型多结构域蛋白，在多种生理过程中具有调节功能，因此具有强大的治疗潜力。在无脊椎动物中，它最初被鉴定为一种水溶性蛋白信息素，在化学通讯中起重要作用并协调生殖活动。但其在蚊子/昆虫中的作用仍不清楚。我们意外地从库蚊按蚊的嗅觉组织中发现了吸引素同源物，这促使我们研究库蚊吸引素（Ac-atrn）在多种行为反应（如取食、交配和其他非遗传应激）中可能发挥的作用。
进行同源性搜索分析以鉴定库蚊按蚊的全长吸引素（Ac-atrn）基因。为了揭示其在外部和内部应激期间的分子功能，在成年蚊子的神经嗅觉组织以及幼虫阶段进行了广泛的实时PCR。此外，进行了行为分析以阐明其在蚊子交配行为中的作用。
结果表明，Ac-atrn是一个3942 bp长的转录本，编码一个1313个氨基酸的蛋白质，具有包括CUB、EGF、凯尔希等在内的多个结构域，与其他昆虫/蚊子同源物具有80-90%的同源性。Ac-atrn基因在幼虫中主要表达，饥饿幼虫在新鲜食物供应时其表达升高。冷应激暂时抑制了Ac-atrn基因的表达。对于成年蚊子，嗅觉和脑组织中Ac-atrn的表达相对高于生殖器官。虽然饥饿在嗅觉组织中未产生显著变化，但衰老和营养应激调节了脑组织中Ac-atrn的表达。此外，未交配和已交配蚊子（雌雄均有）的Ac-atrn表达存在昼夜节律依赖性变化，这表明Ac-atrn在群体形成和交配行为期间可能也具有信息素引导作用。
Ac-atrn基因在幼虫营养和冷应激期间的相对表达谱表明其在介导对食物源的化学通讯以及幼虫热调节中可能发挥的作用。同样，它可能在成年蚊子的应激管理和生存中具有关键调节作用。结果表明，Ac-atrn基因是蚊子许多生理过程（包括应激反应和交配行为）的全局调节因子，因此可能是设计新型蚊虫干预策略的潜在靶点。
