Aisemberg G O, Wong V Y, Macagno E R
Department of Biological Sciences, Columbia University, New York, NY 10027.
EXS. 1995;72:77-87. doi: 10.1007/978-3-0348-9219-3_5.
The Antennapedia-class homeobox genes are likely to play a role in the specification of neuronal identities in invertebrates. The leech Hirudo medicinalis, a species well-suited for the analysis of these genes at the level of identified neurons, contains homologs of many Antennapedia-class and related genes. The expression pattern in the central nervous system of four leech homebox genes was examined in detail. Lox1 is expressed during early gangliogenesis in one pair of transient neurons present in every segment and, at later stages, in 15-20 pairs of neurons per segment. Lox2 is expressed in 25-30 pairs of neurons repeated in the posterior two-thirds of the midbody. Lox4 is present in 20-30 pairs of iterated neurons in the posterior half of the midbody, and in smaller subset of them in more anterior ganglia. Lox6 is expressed in 15-20 pairs of neurons of the third subesophageal neuromere and in fewer cells of more posterior ganglia. The subsets of neurons that express these homeobox genes are different but overlapping. Combinations of Lox genes could in theory generate enough variability to specify all central neurons in a leech ganglion.
触角足类同源异型盒基因可能在无脊椎动物神经元身份的特化过程中发挥作用。水蛭（Hirudo medicinalis）是一种非常适合在已鉴定神经元水平上分析这些基因的物种，它含有许多触角足类及相关基因的同源物。我们详细研究了四种水蛭同源异型盒基因在中枢神经系统中的表达模式。Lox1在早期神经节形成过程中，在每个体节中一对短暂存在的神经元中表达，在后期阶段，每个体节中有15 - 20对神经元表达。Lox2在中体后三分之二重复出现的25 - 30对神经元中表达。Lox4存在于中体后半部20 - 30对重复出现的神经元中，在前部神经节中表达的神经元数量较少。Lox6在第三咽下神经节的15 - 20对神经元以及更靠后神经节中较少的细胞中表达。表达这些同源异型盒基因的神经元子集各不相同但相互重叠。理论上，Lox基因的组合能够产生足够的变异性来确定水蛭神经节中的所有中枢神经元。
