中文摘要：

利用RACE技术从蚤状溞（ Daphnia pluex）中克隆到doublesex（ dpdsx），dpdsx cDNA全长为1636 bp，其中开放阅读框（ ORF）1008 bp，编码335个氨基酸，含有1个DM结构域和1个Dimersation domain。同源性比对结果显示蚤状溞dpdsx与大型溞（ Daphnia magna）同源性最高为77％，其次盔形溞（ Daphnia galeata）为61％，模糊网纹溞（ Ce－riodaphnia dubia）为54％；进化分析发现蚤状溞dpdsx与盔形溞、大型溞、模糊网纹溞等溞科的亲缘关系最近；Real time－PCR实验结果表明，dpdsx在雄溞表达水平最高，其次是孤雌溞（带夏卵）和两性溞（带冬卵），雌溞与雄溞有显著性差异（ P＞0．05）。表明doublesex有可能在蚤状溞生殖转化和性别分化调控上起一定作用。

英文摘要：

The full-length cDNA of a doublesex （ dpdsx） gene was cloned from the cladoceran Daphnia pulex using rapid amplification of complementary DNA ends （ RACE ） method.The dpdsx cDNA is 1636 bp in length; and it has a 1008-bp open reading frame （ ORF） that encodes a 335-amino-acid polypeptide containing a DM structural domain and a dimersation domain.Homology comparison showed Daphnia pulex′s dpdsx sharing homology of up to 77%with Daphnia magna, 61% with Daphnia magna and 54% with Ceri-odaphnia dubia.Phylogenetic analysis revealed that Daphnia pulex′s dpdsx had a close genetic relationship with Daphniidae such as D. magna, D.magna, C.dubia and so on.Real time-PCR showed that dpdsx had the highest expression level in the male, followed by the parthenogenetic female （ with summer egg） and sexual female （ with winter egg） .The expression had significant difference （ P〉0.05） between the male and the female.The experiment indicated that doublesex gene may be play a role in reproduction switching and controlling sex differentiation of D.pulex.