Nef S, Nef P
Department of Biochemistry, University of Geneva, CH-1211 Geneva 4, Switzerland.
Proc Natl Acad Sci U S A. 1997 Apr 29;94(9):4766-71. doi: 10.1073/pnas.94.9.4766.
In vertebrates, odors are thought to be detected by a multigene family encoding several hundreds of seven-transmembrane-domain G-protein-coupled receptors found in fish, rat, mouse, dog, and human. Recently, the putative odorant receptor (OR) gene family in the chicken has been characterized. Twelve members have been isolated and subdivided into six subfamilies. Herein, we have further characterized the chicken olfactory receptor subfamily 7 (COR7) composed of two highly related genes (named COR7a and COR7b) which are 98.5% identical. By in situ hybridization experiments, both COR7a and COR7b transcripts were detected in the olfactory epithelium from embryonic day 6 (E6) to the new born stage. Within the olfactory epithelium, the spatial distribution of COR7a and COR7b labeled cells was random. We also observed that every individual positive cell did not coexpress the COR7a and COR7b genes. Interestingly, the COR7b gene was found to be transiently expressed in the notochord from E2 to E6, whereas COR7a or any of the other known members of the COR gene family were not detected in this mesodermal tissue. These data suggest that, in addition to its potential role as an OR in the olfactory system, COR7b may also have a function in the notochord that is essential for the dorsoventral organization of the neural tube and of the somitic mesoderm. We also discuss the possible role(s) of a putative OR present in both the notochord and the sensory olfactory epithelium.
在脊椎动物中，气味被认为是由一个多基因家族检测到的，该家族编码数百种七跨膜结构域的G蛋白偶联受体，这些受体存在于鱼类、大鼠、小鼠、狗和人类中。最近，鸡的假定气味受体（OR）基因家族已被鉴定。已分离出12个成员并将其细分为6个亚家族。在此，我们进一步鉴定了由两个高度相关的基因（命名为COR7a和COR7b，它们的序列一致性为98.5%）组成的鸡嗅觉受体亚家族7（COR7）。通过原位杂交实验，在胚胎第6天（E6）至新生阶段的嗅觉上皮中均检测到COR7a和COR7b的转录本。在嗅觉上皮内，COR7a和COR7b标记细胞的空间分布是随机的。我们还观察到，每个阳性细胞并不共表达COR7a和COR7b基因。有趣的是，发现COR7b基因在E2至E6期间在脊索中短暂表达，而在该中胚层组织中未检测到COR7a或COR基因家族的任何其他已知成员。这些数据表明，除了其在嗅觉系统中作为OR的潜在作用外，COR7b在脊索中可能也具有对神经管和体节中胚层的背腹组织至关重要的功能。我们还讨论了脊索和嗅觉感觉上皮中都存在的假定OR的可能作用。
