Areawide Pest Management Research, Southern Plains Agricultural Research Center, USDA, 2881 F/B Road, College Station, TX 77845, USA.
Peptides. 2011 Mar;32(3):587-94. doi: 10.1016/j.peptides.2010.09.013. Epub 2010 Oct 1.
The tachykinin-related peptides (TRPs) are multifunctional neuropeptides found in a variety of arthropod species, including the pea aphid Acyrthosiphon pisum (Hemiptera: Aphidae). Two new biostable TRP analogs containing multiple, sterically hindered Aib residues were synthesized and found to exhibit significantly enhanced resistance to hydrolysis by angiotensin converting enzyme and neprilysin, membrane-bound enzymes that degrade and inactivate natural TRPs. The two biostable analogs were also found to retain significant myostimulatory activity in an isolated cockroach hindgut preparation, the bioassay used to isolate and identify the first members of the TRP family. Indeed one of the analogs (Leuma-TRP-Aib-1) matched the potency and efficacy of the natural, parent TRP peptide in this myotropic bioassay. The two biostable TRP analogs were further fed in solutions of artificial diet to the pea aphid over a period of 3 days and evaluated for antifeedant and aphicidal activity and compared with the effect of treatment with three natural, unmodified TRPs. The two biostable multi-Aib TRP analogs were observed to elicit aphicidal effects within the first 24 h. In contrast natural, unmodified TRPs, including two that are native to the pea aphid, demonstrated little or no activity. The most active analog, double-Aib analog Leuma-TRP-Aib-1 (pEA[Aib]SGFL[Aib]VR-NH(2)), featured aphicidal activity calculated at an LC(50) of 0.0083 nmol/μl (0.0087 μg/μl) and an LT(50) of 1.4 days, matching or exceeding the potency of commercially available aphicides. The mechanism of this activity has yet to be established. The aphicidal activity of the biostable TRP analogs may result from disruption of digestive processes by interfering with gut motility patterns and/or with fluid cycling in the gut; processes shown to be regulated by the TRPs in other insects. These active TRP analogs and/or second generation analogs offer potential as environmentally friendly pest aphid control agents.
速激肽相关肽 (TRP) 是一种多功能神经肽，存在于多种节肢动物物种中，包括豌豆蚜 Acyrthosiphon pisum（半翅目：蚜科）。两种新的生物稳定的 TRP 类似物含有多个空间位阻的 Aib 残基，被合成并发现对血管紧张素转换酶和 Neprilysin 的水解具有显著增强的抗性，血管紧张素转换酶和 Neprilysin 是降解和失活天然 TRP 的膜结合酶。这两种生物稳定的类似物在离体蟑螂后肠制剂中也被发现保留了显著的肌刺激活性，该生物测定用于分离和鉴定 TRP 家族的第一个成员。事实上，其中一种类似物（Leuma-TRP-Aib-1）在这种肌营养生物测定中与天然母体 TRP 肽的效力和功效相匹配。这两种生物稳定的 TRP 类似物进一步在人工饮食溶液中喂食豌豆蚜 3 天，并评估其抗食和杀虫活性，并与三种天然、未修饰的 TRP 处理的效果进行比较。在最初的 24 小时内，观察到这两种生物稳定的多 Aib TRP 类似物引起杀虫作用。相比之下，包括两种天然存在于豌豆蚜中的天然、未修饰的 TRP 表现出很少或没有活性。最有效的类似物，双 Aib 类似物 Leuma-TRP-Aib-1（pEA[Aib]SGFL[Aib]VR-NH2），具有计算得出的 LC50 为 0.0083 nmol/μl（0.0087 μg/μl）和 LT50 为 1.4 天的杀虫活性，与市售杀蚜剂的效力相匹配或超过。这种活性的机制尚未建立。生物稳定的 TRP 类似物的杀虫活性可能是通过干扰肠道运动模式和/或肠道中的液体循环来破坏消化过程而产生的；在其他昆虫中，这些过程被证明受 TRP 调节。这些有效的 TRP 类似物和/或第二代类似物有希望成为环保型的蚜虫控制剂。
