Hemalin, a thrombin inhibitor isolated from a midgut cDNA library from the hard tick Haemaphysalis longicornis
Hemalin, a thrombin inhibitor isolated from a midgut cDNA library from the hard tick Haemaphysalis longicornis
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DOI：
10.1016/j.jinsphys.2008.11.004
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发表时间：
2009-02-01
影响因子：
2.2
通讯作者：
Fujisaki, Kozo
中科院分区：
文献类型：
--
作者：
Liao, Min;Zhou, Jinlin;Fujisaki, Kozo
从孤雌生殖的长角血蜱中肠中鉴定了一种凝血酶抑制剂（命名为血红素）的全长序列。序列分析表明，该基因属于Kunitz型家族，含有两个Kunitz结构域，与微小扇头蜱（Rhipicephalus（Boophilus）microplus）的凝血酶抑制剂boophilin具有高度同源性。在昆虫细胞中表达的重组蛋白延迟牛血浆凝固时间，抑制凝血酶诱导的纤维蛋白原凝固和血小板聚集。一个20-kDa的蛋白质，从中肠裂解物与抗重组血红素。该基因在除卵期外的蜱的所有阶段都有表达，并且血红素mRNA主要在雌性成年蜱的中肠中表达。实时荧光定量PCR分析表明，该基因在幼虫、成虫和成虫的快速吸血期有明显的高表达。通过RNA干扰破坏血红素基因导致蜱吸血期延长2天，27.7%的RNA处理蜱未成功完成吸血。这些结果表明，新发现的凝血酶抑制剂，从中肠的H。长角蜱可能在蜱吸血中起重要作用。(c)2008爱思唯尔有限公司保留所有权利。
A full-length sequence of a thrombin inhibitor (designated as hemalin) from the midgut of parthenogenetic Haemaphysalis longicornis has been identified. Sequence analysis shows that this gene belongs to the Kunitz-type family, containing two Kunitz domains with high homology to boophilin, the thrombin inhibitor from Rhipicephalus (Boophilus) microplus. The recombinant protein expressed in insect cells delayed bovine plasma clotting time and inhibited both thrombin-induced fibrinogen clotting and platelet aggregation. A 20-kDa protein was detected from the midgut lysate with antiserum against recombinant hemalin. The gene is expressed at all stages of the tick except for the egg stage, and hemalin mRNA mainly in the midgut of the female adult tick. Real-time PCR analysis shows that this gene has a distinctly high expression level in the rapid bloodsucking period of the larvae, nymphs, and adults. Disruption of the hemalin gene by RNA interference led to a 2-day extension of the tick blood feeding period, and 27.7% of the RNA-treated ticks did not successfully complete the blood feeding. These findings indicate that the newly identified thrombin inhibitor from the midgut of H. longicornis might play an important role in tick blood feeding. (c) 2008 Elsevier Ltd. All rights reserved.