Macdonald M, Lutz E M, Lesser W, Cottrell G A, Sommerville J
School of Biological and Medical Sciences, University of St Andrews, Fife, Scotland.
Mol Cell Neurosci. 1994 Feb;5(1):23-34. doi: 10.1006/mcne.1994.1003.
The FMRFamide-related peptides (FaRPs) of Helix fall into two groups with often different pharmacological effects: the tetrapeptides FMRFamide and FLRFamide (tetraFaRPs) and the heptapeptides, which have the general structure XDP(F or Y)LRFamide (heptaFaRPs). Previously, we have shown that each group of FaRPs is encoded within a separate type of cDNA clone, a situation which corresponds to two distinct mRNA species existing in the CNS of Helix. Here, we report on the expression patterns of the two FaRP mRNAs both through embryo-genesis and in the fully differentiated regions of the adult nervous system. The levels and locations of FaRP mRNAs were studied by molecular and in situ hybridization using antisense riboprobes. The onset of expression of FaRP mRNAs occurs in Helix embryos about half-way between egg laying and hatching. First detection of the FaRPs themselves occurs about 2 days later. In embryos, as in the adult CNS, the heptaFaRP mRNA is at least five times more abundant than the tetraFaRP mRNA. In adults, the tetraFaRP mRNA is located primarily in the cerebral ganglia, most obviously in the C3 neuron, but also in a crescent-shaped cluster of small neurons lying anterior to C3. Occasional neurons expressing the tetraFaRP mRNA are detected in the parietal ganglia, but these have not yet been mapped. In contrast, the heptaFaRP mRNA is expressed almost exclusively in the parietal ganglia: in large clusters of about 100 neurons lying near to the anterior surface. The most interesting aspect of FaRP mRNAs is that their expression is not only exclusive to a relatively small number of specified neurons, but that expression appears to be mutually exclusive, that is, a particular neuron expresses only the mRNA for tetra-FaRPs or heptaFaRPs, never both. These results are discussed in relation to what we now know about the structure of the individual mRNA molecules.
椎实螺的FMRF酰胺相关肽（FaRPs）分为两组，其药理作用往往不同：四肽FMRF酰胺和FLRF酰胺（四肽FaRPs）以及七肽，其一般结构为XDP（F或Y）LRF酰胺（七肽FaRPs）。此前，我们已经表明，每组FaRPs都在一种单独类型的cDNA克隆中编码，这种情况对应于椎实螺中枢神经系统中存在的两种不同的mRNA种类。在此，我们报告了两种FaRP mRNA在胚胎发育过程中和成年神经系统完全分化区域中的表达模式。使用反义核糖探针通过分子杂交和原位杂交研究了FaRP mRNA的水平和位置。FaRP mRNA的表达起始于椎实螺胚胎，大约在产卵和孵化的中间阶段。FaRPs本身的首次检测大约在两天后。在胚胎中，与成年中枢神经系统一样，七肽FaRP mRNA的丰度至少是四肽FaRP mRNA的五倍。在成体中，四肽FaRP mRNA主要位于脑神经节，最明显的是在C3神经元中，但也存在于位于C3前方的新月形小神经元簇中。在顶神经节中偶尔检测到表达四肽FaRP mRNA的神经元，但尚未对其进行定位。相比之下，七肽FaRP mRNA几乎只在顶神经节中表达：在靠近前表面的大约100个神经元的大簇中。FaRP mRNA最有趣的方面是，它们的表达不仅限于相对少数特定的神经元，而且表达似乎是相互排斥的，也就是说，一个特定的神经元只表达四肽FaRPs或七肽FaRPs的mRNA，从不两者都表达。结合我们现在对单个mRNA分子结构的了解，对这些结果进行了讨论。
