L-type lectins (LTLs) belong to the lectin family and are characterized by a conserved structural motif in their carbohydrate recognition domain. LTLs are homologous to leguminous lectins. In this study, we identified and functionally characterized an LTL from kuruma shrimp Marsupenaeus japonicus. We designated this LTL as MjLTL2. MjLTL2 contains a signal peptide, a Lectin_leg domain, a coiled coil, and transmembrane domain. MjLTL2 is distributed in hemocytes, heart, hepatopancreas, gill, stomach, and intestine; higher expression levels are seen in hemocytes and the hepatopancreas than in other tissues. MjLTL2 was upregulated following challenge of shrimp with Vibrio anguillarum and white spot syndrome virus (WSSV). MjLTL2 can agglutinate several bacteria without Ca2+. In addition, MjLTL2 could bind to several Gram-positive and -negative bacteria by binding to their lipopolysaccharide and peptidoglycan. However, MjLTL2 could not enhance the clearance of V. anguillarum in vivo. In the presence of WSSV infection, MjLTL2 knockdown by RNA interference resulted in a 7-day lower cumulative mortality of M. japonicus. Moreover, less VP19, VP24, VP26, and VP28 mRNAs were extracted from the hemocytes of MjLTL2 knockdown shrimp than from the control. These results suggest that MjLTL2 is involved in immune responses in shrimp.

中文翻译：

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鉴定和表征一种新型的L型凝集素（MjLTL2），来自库鲁玛虾（Marsupenaeus japonicus）。

L型凝集素（LTL）属于凝集素家族，其特征是在其碳水化合物识别域中具有保守的结构基序。LTL与豆科植物凝集素同源。在这项研究中，我们从黑熊虾Marsupenaeus japonicus中鉴定了LTL并对其功能进行了表征。我们将此LTL指定为MjLTL2。MjLTL2包含信号肽，Lectin_leg域，卷曲螺旋和跨膜结构域。MjLTL2分布在血细胞，心脏，肝胰脏，ill，胃和肠中。血细胞和肝胰腺中的表达水平高于其他组织。在用鳗弧菌和白斑综合症病毒（WSSV）攻击虾后，MjLTL2上调。MjLTL2可以在没有Ca2 +的情况下凝集多种细菌。此外，MjLTL2通过与脂多糖和肽聚糖结合，可以与几种革兰氏阳性和阴性细菌结合。但是，MjLTL2不能提高体内弧菌的清除率。在存在WSSV感染的情况下，RNA干扰导致的MjLTL2敲低导致日本分枝杆菌的累积死亡率降低了7天。此外，与对照相比，从MjLTL2敲低对虾的血细胞中提取的VP19，VP24，VP26和VP28 mRNA更少。这些结果表明，MjLTL2参与了虾的免疫反应。MjLTL2基因敲除虾的血细胞比对照提取了VP28和VP28 mRNA。这些结果表明，MjLTL2参与了虾的免疫反应。MjLTL2基因敲除虾的血细胞比对照提取了VP28和VP28 mRNA。这些结果表明，MjLTL2参与了虾的免疫反应。