Hansen G N, Williamson M, Grimmelikhuijzen C J
Department of Cell Biology, Zoological Institute, University of Copenhagen, Denmark.
Cell Tissue Res. 2000 Aug;301(2):245-53. doi: 10.1007/s004410000240.
The freshwater polyp Hydra magnipapillata has a primitive nervous system that produces at least three distinct classes of neuropeptides: various peptides having the C-terminal sequence Arg-Phe-NH2 (the Hydra-RFamide family), Leu-Trp-NH2 (the Hydra-LWamide family), and a single peptide having the C-terminal sequence Lys-Val-NH2 (Hydra-KVamide). The various Hydra-RFamides are synthesized by three different preprohormones: preprohormone-A, -B, and -C. The various Hydra-LWamides are synthesized by a single preprohormone (prepro-Hydra-LWamide), as is Hydra-KVamide (prepro-Hydra-KVamide). Using a wholemount double-labeling two-color in situ hybridization technique and RNA probes specific for each of these five Hydra preprohormone mRNAs, we found that specific sets of neurons express each of the five preprohormones, except for the peduncle region of Hydra (an area just above the basal disk), where a population of neurons exists that expresses both preprohormones-A and preproHydra-KVamide mRNAs. The functional significance of this coexpression is unclear. This is the first report on the coexpression of two well-characterized preprohormones (yielding two well-characterized neurohormone families) in cnidarians. This report also shows that there are at least six neurochemically different populations of neurons in Hydra.
淡水水螅（Hydra magnipapillata）具有原始的神经系统，可产生至少三类不同的神经肽：具有C末端序列Arg-Phe-NH2的各种肽（水螅-RFamide家族）、Leu-Trp-NH2（水螅-LWamide家族），以及一种具有C末端序列Lys-Val-NH2的单一肽（水螅-KVamide）。各种水螅-RFamides由三种不同的前激素原合成：前激素原-A、-B和-C。各种水螅-LWamides由单一的前激素原（前水螅-LWamide原）合成，水螅-KVamide也是如此（前水螅-KVamide原）。使用全组织双色原位杂交技术和针对这五种水螅前激素原mRNA的特异性RNA探针，我们发现特定的神经元群表达这五种前激素原中的每一种，但水螅的柄部区域（基盘上方的区域）除外，在该区域存在一群同时表达前激素原-A和前水螅-KVamide mRNA的神经元。这种共表达的功能意义尚不清楚。这是关于刺胞动物中两种特征明确的前激素原（产生两个特征明确的神经激素家族）共表达的首次报道。本报告还表明，水螅中至少有六个神经化学不同的神经元群。
