Type 1 vomeronasal receptors expressed in the olfactory organs of two African lungfish, Protopterus annectens and Protopterus amphibius
Type 1 vomeronasal receptors expressed in the olfactory organs of two African lungfish, Protopterus annectens and Protopterus amphibius
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DOI：
10.1002/cne.25416
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发表时间：
2022-09-26
影响因子：
2.5
通讯作者：
Nakamuta，Nobuaki
中科院分区：
文献类型：
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作者：
Nakamuta，Shoko;Yamamoto，Yoshio;Nakamuta，Nobuaki
肺鱼是与四足动物关系最密切的鱼类。肺鱼的嗅觉器官包括两个不同的感觉上皮：板层嗅上皮（OE）和隐窝上皮（RecE）。根据它们的超微结构和组织学特征，板层OE和RecE被认为分别对应于硬骨鱼OE和原始犁鼻器（VNO）。在四足动物中，OE和VNO已被证明表达不同家族的嗅觉受体;例如，在哺乳动物中，OE表达气味受体和痕量胺相关受体，而VNO表达1型（V1 Rs）和2型（V2 Rs）犁鼻受体。在本研究中，我们检测了V1 Rs在两种非洲肺鱼（Protopterus annectens和Protopterus amphitus）嗅觉器官中的表达。RNA测序和系统发育分析鉴定出29个V1 R基因。和50个V1 R基因。两栖动物在这些肺鱼中发现的大多数V1 R被归类为最初在四足动物中发现的四足动物型V1 R，与鱼类型V1 R不同。在硬骨鱼中，它们都缺乏VNO，所有的嗅觉受体都在OE中表达，而在XenopusV 1 Rs只在OE中表达，而不在VNO中表达。原位杂交分析表明，肺鱼V1 Rs主要表达在板层OE和很少在RecE。这些结果表明，V1 R在肺鱼的表达代表了一个中间步骤，完全分离的V1 R表达之间的OE和VNO，反映了肺鱼之间的硬骨鱼和两栖类的系统发育位置。
Lungfish are the fish related most closely to tetrapods. The olfactory organ of lungfish contains two distinct sensory epithelia: the lamellar olfactory epithelium (OE) and the recess epithelium (RecE). Based on their ultrastructural and histological characteristics, the lamellar OE and the RecE are considered to correspond respectively to the teleost OE and a primitive vomeronasal organ (VNO). In tetrapods, the OE and VNO have been shown to express different families of olfactory receptors; for example, in mammals, the OE expresses odorant receptors and trace amine‐associated receptors, while the VNO expresses type 1 (V1Rs) and type 2 (V2Rs) vomeronasal receptors. In the present study, we examined the expression of V1Rs in the olfactory organs of two African lungfish,Protopterus annectensandProtopterus amphibius. RNA sequencing and phylogenetic analyses identified 29 V1R genes inP. annectensand 50 V1R genes inP. amphibius. Most V1Rs identified in these lungfish were classified as the tetrapod‐type V1Rs initially found in tetrapods and distinct from fish‐type V1Rs. In teleost, which all lack a VNO, all olfactory receptors are expressed in the OE, while inXenopusV1Rs are expressed exclusively in the OE, and not in the VNO. In situ hybridization analysis indicated that lungfish V1Rs were expressed mainly in the lamellar OE and rarely in the RecE. These results imply that V1R expression in lungfish represents an intermediate step toward the complete segregation of V1R expression between the OE and VNO, reflecting the phylogenetic position of lungfish between teleosts and amphibians.