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摘要Cell contains different kind of microdomains at its plasma membrane for various cellular functions. One of such microdomains at the plasma membrane is called caveolae. The caveolae is a flask shaped invagination measuring 50-100 nm in size, and is present at the plasma membrane of most vertebrate cell types but absent in plant, fungi and unicellular organism. It was first observed in the blood capillaries using electron microscope. Later it was named‘Caveola Intercellularis’ meaning little cave at the plasma membrane. Mainly adipocytes, endothelial cell, muscle cell and fibroblast show large number of caveolae at the plasma membrane of vertebrate. The main component of caveolae is caveolins protein, but recently cavins protein has been proven to be essential for generation and maintenance of caveolae shape in the vertebrate cell. Other proteins found in the caveolae are Pascin, EHD, Dynamin etc. The caveolins are membrane protein with oligomerization, scaffolding and intramembrane domains. It forms a hairpin loop structure at the plasma membrane. There are three caveolins in the mammalian genomes with different expression patterns. Moreover, only Cav1 and Cav3 form caveolae in the mammalian cell but not by Cav2.<br>　　Ciona savignyi is a marine invertebrate chordate found mostly in the benthic environment of the sea. It belongs to tunicate family, and is used as a model animal for the study of development and evolution. The genome of C. savignyi is available and contains approximately twelve thousand genes. There are several advantages in using Ciona as a model animal for example the embryo is semi-transparent, the development is fast, the genome is sequenced and the genetic toolkits are available for embryonic development study. Furthermore, from the evolutionary point of view, it is closest to the vertebrate, therefore, it is used for the comparative study on the origin of vertebrate and different vertebrate tissues.<br>　　In C. savignyi genome, there are three caveolins genes. We identified and named them as Cav-a, Cav-b and CavY. The Cav-a and CavY have three exons and two introns, but Cav-bamp;nbsp;have two exons and one intron. In addition, the protein sequence comparison show that Cav-a is more similar to CavY than Cav-b. While in phylogenetic analysis, we found that Cav-a clusters with vertebrate Cav1, suggesting that Cav-a may have similar functions as vertebrate Cav1. The quantitative real time PCR shows that Cav-a and Cav-b expression level is comparatively higher in the embryo, while the expression level of CavY is negligible. However, in the adult stage, the CavY expression level is detected significantly. We focus our study in Cav-a only during Ciona embryo morphogenesis because it is related to the vertebrate Cav1 from the phylogenetic analysis, and its expression level is also higher in the embryo. At the early developmental stage, the Cav-a mRNA localization is limited to the muscle only but later its localization is detected both in muscle and notochord of the embryo by in situ hybridization. Furthermore, the promoter analysis confirms that Cav-a expression is initially in the muscle only and later detected both in muscle and notochord. In the immunohistochemistry experiment also, the Cav-a protein localizes initially in muscle only but later it localizes both in muscle and notochord. Interestingly, the Cav-a protein localizes at luminal membrane of the notochord cell. Therefore, we hypothesize that Cav-a may have a role in vesicles trafficking during lumen formation in Ciona notochord.