title: Identification and expression analysis of a doublesex1 gene in Daphnia pulex during different reproductive stages.
abstract: The gene doublesex (dsx) has shown deep conservation in the sex determination in many organisms. Environmental stimuli initiate a switch in the reproductive strategy of Daphnia pulex from asexual to sexual reproduction; however, occasionally, changes in environmental conditions will not lead to this transition. So study genetic responses to environmental stimuli and the molecular basis for the switch of reproductive stages are urgently needed. Therefore, we isolated and sequenced a D. pulex doublesex1 gene (Dpdsx1) and analyzed its expression and location by quantitative polymerase chain reaction (qPCR) and whole-mount in situ hybridization in D. pulex during different stages of reproduction. The predicted amino acid sequence has 335 amino acids that contained one DM domain and one dimerization domain, which is characteristic of insect orthologs of Dsx. Real-time PCR showed that Dpdsx1 expression decreased significantly (P < 0.05) in different reproductive stages in the following order: male, parthenogenetic female, ephippial female, resting egg, and juvenile female. Whole-mount in situ hybridization revealed that Dpdsx1 is expressed in the first antennae, first thoracic limb and compound eye in males, whereas expression levels in the corresponding sites of parthenogenetic and ephippial females were relatively weak. Dpdsx1 could not be detected in the gonads of males or ephippial and parthenogenetic females. Taken together, these different reproductive stages' and sex specific expression patterns are regulated temporally and spatially. We speculate that Dpdsx1 may involve in switching different stages of reproduction and in sexual differentiation in D. pulex.
authors.affiliation: School of Marine Sciences, Ningbo University, Feng-Hua Road 818, Jiangbei District, Ningbo, China.
authors.forename: Shan-Liang
authors.initials: SL
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.forename: Jian-Kai
authors.initials: JK
authors.lastname: Zhou
authors.forename: Xiu
authors.initials: X
authors.lastname: Zou
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Wang
authors.forename: Dan-Li
authors.initials: DL
authors.lastname: Wang
authors.forename: Yun-Long
authors.initials: YL
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D003621:Daphnia / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D021141:Nucleic Acid Amplification Techniques; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D012098:Reproduction; D016415:Sequence Alignment
chemical_list: D060829:Arthropod Proteins; D004268:DNA-Binding Proteins