| Carinata (Daphnia carinata) commonly known as fish food, and it was an important component of zooplankton. Carinata belongs to Arthropoda, Crustacea, Daphnia Branch, Daphnia spp. Daphnia was rich in protein material and it was a freshwater fish and invertebrates's natural food. Same time, it can indicate the environment of toxic substances, often used as indicator organism. In addition, Daphnia carinata its Special mode of reproduction was a hot research. When environmental conditions were good, for example, temperature, food, density was more appropriate it for parthenogenesis, the offspring are female Daphnia. We called this egg, which hatch female Daphnia, parthenogenesis eggs. We also called it summer eggs. When environmental conditions were bad, they turn to sexual reproduction. They not only produce females also produced males. Then females and males mating, and produce sexual eggs. The sexual eggs never output until the environmental conditions improved, then they hatch into parthenogenetic reproduction of Daphnia. Many scholars were interested in exploring the internal mechanism of the reproductive transformation, but the mechanism of regulation was not yet deeply touched. In this paper, the cuticle protein gene of Daphnia carinata wre researched, in order to help clarifing the mechanism of the mechanism of regulation.Cuticle protein gene (cuticle protein gene) also known as epidermal protein gene, according to the conserved motif protein can be divided into CPR, CPF, CPFL, CPG, and CPT five families, each family has its unique structure and Nature. Epidermal protein is a structural protein, which, composed of chitin with a barrier against external environment. Daphnia carinata were bisexual, and its winter eggs covered an thick shell to resist the external environment in a variety of adverse conditions. Xiaoqian- Xu and Fen-Qing built an Daphnia carinata cDNA library, found that Daphnia cuticle protein gene was largely existenced in the sexual body but very little in parthenogenetic body. Therefore we assume that the gene may be involved in the reproductive transformation process. By controlling the external environmental conditions, prompting Daphnia change from parthenogenesis.to sexual reproduction, the Daphnia cuticle protein gene analysis and study. It was designed to explore the transformation mechanism of Daphnia. The main results of this study were as follows:1. A number of ecological factors on the growth of Daphnia carinata reproductionBy regulating the temperature, pH, density, food and chemical stimuli such as environmental factors, the growth of Daphnia carinata and reproductive were studed. The intrinsic of increase (rm), finite rate of increase (λ), mean generation time (T), net reproduce rate (Ro), mean lifespan, age at first brood, mean interval between clutch and fecundity of Daphnia carinata were studied under different temperature (15,20, 25,30℃)and pH (6,7,8,9,10). The results indicated that temperature is of great importance to the reproduction of D. carinata. The mean generation time (T), mean lifespan, age at first brood, mean interval between clutch decreased with increasing temperature in this experiment, also intrinsic of increase (rm) and finite rate of increase (λ) increased with temperature varying from 15-30℃. Among those experimental groups, the intrinsic of increase (rm) at 30℃, which was significantly higher than other groups. Effects of pH on the survival and neonate production of D. carinata were also studied in present study. Results showed that there was no significantly difference among pH7,8,9 and 10. When D. carinata was reared at pH 6, intrinsic of increase (rm) and finite rate of increase (λ) was significantly higher than those were reared at other groups. In this research, after inducing by four environmental factors which is temperature, popular number, food and chemicals, we detected the parthenogenesis Daphnia turn to sexual reproduction Daphnia. It should have further study on the quantitative analysis.2. Studies on cloning, characterization, expression of the cuticle protein gene in the Daphnia (Ctenodaphnia) carinataA cDNA encoding Daphnia carinata cuticle protein gene was cloned based upon EST analysis of a cDNA library. The full length cDNA was 78.1 bp and encoded a 219 aa polypeptide that was highly homologous to related genes reported in Daphnia magna. The 1600 bp cuticle protein gene contained four exons that were interrupted by three introns. Gene expression analysis, as determined by RT-PCR, revealed the high presence of cuticle protein gene transcripts in the sexual Daphnia, but low presence in the parthenogenesis Daphnia. In this research, we found that Daphnia carinata cuticle protein gene may play important roles in regulating the transformation of reproduction, however, the specific regulatory mechanisms were not yet clearly needs further study.
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