A Preliminary Study On Cement Gland And Cement Proteins Of Capitulum Mitella

Histology and ultrastructure of the cement apparatus of Capitulum mitella were observed by light microscope and electron microscope. The results show that the cement apparatus of C. mitella is consisted of gland cells and canal system.The cement apparatus is sheathed in a layer of connective tissue membrane. Gland cell is a unicellular gland. Development of gland cells and animal itself is not synchronous. Young gland cells are small, and the shape of cells and nucleus is round, ovoid. With development of cement gland, gland cells and their nucleus enlarge, and their shape becomes irregular with polymorphism. The cytoplasm of mature gland cells, electron density of which is high, is full of a lot of rough endoplasmic reticulums, many free ribosomes, a few of mitochondrias, but no Golgi body. The cytoplasm contains a wealth of particulate matters and different vacuoles in size. Formation of intracellular canal in gland cells is via aggregation and fusion of cytoplasmic vacuoles. The canal system is divided into four levels depending on location and function:intracellular cancel, collection cancel, secondary cancel, principal cancel. The collection canal, the secondary canal, and the principal canal are composed of monolayer epithelial cells. The principal cancel is larger than secondary cancel and collection cancel. The lumen of the principal cancel is lined by a dense cuticle layerl. Septate junction connects gland cells with wall cells of the collector canal. The wall epithelial cells of canals are also connected by septate junction. This structure ensures tightness of the canal system. Morphological structure of the cement apparatus in C. mitella is similar to that of Lepas anatifera and Dosima fascicularis.Sufficient secondary cement was separately placed in 1%、2%、5% SDS-2Me solution in the constant temperature of 38℃ for 5 days, centrifugated. Then the insoluble portion was added SDS-2Me solution. The step was repeated twice, the entire process lasted 15 days. The results show that the average amount of the dissolved cement in 1%、2%、5% of SDS-2Me solution is respectively 50.3%、57.0% and 51.7%. The cement sample was placed into lOmM sodium phosphate buffer with 6M guanidine hydrochloride. The results show that the average amount of the dissolved cement is 23.8%. After that, the insoluble portion was put into 1.5M Tris-HCl with 0.5M DTT,7M guanidine hydrochloride and 20mMEDTA, shocked 1h in the constant temperature of 60 ℃, and added 2.5 wt. iodoacetic acid under the condition of dark treatment for 20min, then added an excess of 2-Me. Finally, the average amount of dissolved cement is 72.4%.The polypeptide liquid of several solvent treatment was analyzed by vertical discontinuous polyacrylamide gel electrophoresis, and the number, molecular weight and staining intensity of its protein were compared. The results show all of the polypeptide liquid have a molecular weight of 36kD protein in common, stained deeper lane means higher protein content, the number of protein lanes is from 1 to 7. The amino acid composition of cement protein and 36kD protein in C. mitella was tested. The results show that the content of three kinds of amino acid (Gly、Arg、Leu) is very high, the Cys content is very low in cement protein. The content of the three amino acid is more than 10%..In 36kD protein the content of three kinds of amino acid (Glu、Cys、Pro) is high.Totle content of three amino acids are more than 60%.