Differential protein expression between parthenogenetic and sexual female of Daphnia(Ctenodaphnia)carinata
【摘要】：正There are two different reproductive modes in daphnids: parthenogenetic and sexual reproduction, but the mechanism of reproductive switch has not been elucidated so far. In present study, water-soluble proteins were isolated from parthenogenetic and sexual females of Daphnia(Ctenodaphnia) carinata respectively, then profiled by two-dimensional polyacrylamide gel electrophoresis and identified by mass spectrometry. Firstly, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed that each sample had a complex and characteristic protein distribution. More than 4 protein bands at approximately 50.6 kDa, 36.2 kDa, 32.1kDa and 25.7kDa were dominant in parthenogenetic female sample. And 4 bands at approximately 87.8 kDa, 67.2 kDa, 53.6 kDa and 35.5kDa were dominant in sexual female sample, in which the 35.5 kDa band appeared especial to the sexual female. The results of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) including high resolution and reproducibility were obtained with four repeated assays. Averagely about 750 and 720 spots were visualized respectively by sliver staining in 2D gel of parthenogenetic and sexual female. When the reproductive mode of D. carinata had switched from parthenogenetic to sexual reproduction, 18 proteins were shown to display significant and reproducible changes by semiquantitative analysis with ImageMaster 2D platinum version 4.10. Among them, 14 proteins were down-regulated while other 4 proteins were up-regulated. Taking 4 up-regulated proteins for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), 2 proteins (No. 16 and No. 17) were further identified. No. 16 protein was a branched acid dehydrogenase (21234), which is expressed at high level at all stages of development, especially greatly expressed from parthenogenetic to sexual reproduction in D. carinata. No. 17 protein was a predicted CDS, putative protein (4E644), but its function was unclear so far. The results showed that there were definite differences of protein expression from parthenogenetic to sexual reproduction in D. carinata. These would provide bases for further research on the molecular mechanism of reproductive switch in daphnids and also might provide new ideas and methods to study the animal's reproduction.