Deciphering the Functions of Gustatory Receptors In the Recognition of Host Plant and Midgut Environment Using Knockout Silkworms

我们首先利用RT-PCR研究了BmGr4基因在不同组织中的表达，BmGr4基因可能是糖枝基因家族的成员。BmGr4在中肠和中枢神经系统表达。此外，用抗BmGr4抗血清进行免疫组织化学染色表明，BmGr4在中肠和神经系统的细胞中表达。免疫组织化学双重染色显示，BmGr4在中肠内分泌细胞和中枢神经分泌细胞中均有表达。特别是，在中肠和中枢神经系统中，部分表达BmGr4的细胞分泌速激肽。这些结果表明，BmGr4不仅是一种味觉感受器，而且还是一种化学感受器，如调节幼虫的肠道运动、生理条件和取食行为。

We first used RT-PCR to investigate expression of BmGr4 gene, a member of the putative sugar clade gene family in various tissues. BmGr4 is expressed in the midgut and central nervous system (CNS). Moreover, immunohistochemistry using an anti-BmGr4 anti-serum demonstrated that BmGr4 is expressed in cells by midgut and nervous system. Furthermore, double-immunohistochemistry indicated that BmGr4 is expressed in midgut enteroendocrine cells, also in CNS neurosecretory cells. In particular, a portion of BmGr4-expressing cells, in both midgut and CNS, secretes tachykinin peptides. These results suggest that BmGr4 functions not only as a taste receptor, but also as a chemical sensor such as for the regulation of gut movement, physiological conditions, and feeding behavior of larvae.