Macins A, Meredith J, Zhao Y, Brock H W, Phillips J E
Department of Zoology, University of British Columbia, Vancouver, Canada.
Arch Insect Biochem Physiol. 1999;40(2):107-18. doi: 10.1002/(SICI)1520-6327(1999)40:2<107::AID-ARCH5>3.0.CO;2-B.
Comparison of the sequence and biological activity of ITP-related proteins from other insects on Schistocerca hindgut will provide further understanding of ITP interaction with its receptor (ITPR) and may thus open new avenues of insect pest control if good ITPR antagonists can be developed. Using a specific bioassay (measurement of ileal Cl- transport) and Western blot analysis with antibodies raised to Schistocerca ion transport peptide (ScgITP) sequences, we demonstrate stimulatory ITP-related peptides in the corpora cardiaca (CC) of several othopteran insects (Schistocerca gregaria, Locusta migratoria, Melanoplus sanguinipes, Xanthippus corallipes, Carausius morosus, Periplaneta americana and Acheta domesticus.). For the first time, we have immunologically detected ITP in Schistocerca brain, the tissue in which ITP transcripts are found and which has some activity in the bioassay. Neither reciprocal bioassays nor immunological results reveal any differences between two locust species, Locusta and Schistocerca, which is consistent with cDNA analysis. Using Schistocerca-derived primers and the polymerase chain reaction (PCR), we show that Locusta brain contains RNA encoding for peptides with identical sequence to ScgITP and with only a single neutral amino acid change from Schistocerca ion transport-like peptide (ScgITP-L). We present evidence that ITP-L transcripts are present in at least 3 locust/grasshopper genera but have been unable to detect ITP-L peptide to date in any tissues assayed by Western blotting at a detection limit of 0.8 pmol/tissue. Results indicate high conservation of ITP structure and biological activity among these orthopteroids, in contrast to several other insect orders.
比较其他昆虫中与ITP相关的蛋白质在沙漠蝗后肠中的序列和生物活性，将有助于进一步了解ITP与其受体（ITPR）的相互作用，因此，如果能开发出良好的ITPR拮抗剂，可能会开辟害虫防治的新途径。通过特定的生物测定法（测量回肠氯离子转运）和使用针对沙漠蝗离子转运肽（ScgITP）序列产生的抗体进行蛋白质印迹分析，我们在几种直翅目昆虫（沙漠蝗、飞蝗、美洲沙漠蝗、珊瑚黄腿蝗、灰翅夜蛾、美洲大蠊和家蟋蟀）的心侧体（CC）中发现了具有刺激作用的与ITP相关的肽。我们首次在沙漠蝗脑中通过免疫检测到了ITP，在该组织中发现了ITP转录本，并且该组织在生物测定中具有一定活性。相互生物测定和免疫结果均未揭示飞蝗和沙漠蝗这两种蝗虫之间的任何差异，这与cDNA分析结果一致。使用源自沙漠蝗的引物和聚合酶链反应（PCR），我们发现飞蝗脑中含有编码与ScgITP序列相同且与沙漠蝗离子转运样肽（ScgITP-L）仅存在一个中性氨基酸差异的肽的RNA。我们提供的证据表明，ITP-L转录本存在于至少3个蝗虫/蚱蜢属中，但迄今为止，在通过蛋白质印迹法检测的任何组织中，检测限为0.8 pmol/组织时，均未检测到ITP-L肽。结果表明，与其他几个昆虫目相比，这些直翅目昆虫中ITP的结构和生物活性具有高度保守性。
