Expression analysis of Djsix-1 gene during regeneration of planarian eyespots.

Djsix-1 gene is one of the important eyespots-regulating genes in planarians. In this experiment, the expression of Djsix-1 and morphogenesis of eyespots during planarians eyespots regeneration were investigated. The planarians were subjected to two rounds of transverse amputation. Nineteen time points in the first round and ten ones in the second one during the regeneration of the planarians post-auricle fragments were selected. At different time points, the quantitative expression of Djsix-1 and morphogenesis of eyespots during eyespots regeneration were examined by real-time RT-PCR and paraffin sections. Results showed that the optimal growth temperature for planarians regeneration was 22°C in dark. At this temperature, Djsix-1 gene was first up-regulated at the 30th min after the first round of transverse amputation and its expression level increased at the 24-h time point. The expression level reached peak on day 4 and then began to decrease thereafter. From day 6 to day 9, the expression level was maintained in a relatively stable level. In the second round, Djsix-1 expression reached the peak on the 2nd day after amputation, and then began to decrease and maintained in a relatively stable level from the 4th to the 9th day. Morphological and histological examinations showed that eyespots were observed on the 4th day after amputation in the first round and on the 3rd day in the second round. These results indicated that corresponding relationship existed between eyespots morphogenesis and Djsix-1 quantitative expression. It was also suggested that Djsix-1 promoted neoblasts proliferation at the early stage of eyespots regeneration and regulated morphogenesis of eyespots at the later stage.