Invivo And In Vitro Studies On The Shell Biomineralization Of Haliotis Discus Hannai Ino

A series experiments were conducted to investigated the mechanism of biomineralization. The current studies include: (1)by the means of "plat pearl",the shell biomineralization of Haliotis discus hannai Ino is studied; The effect of dietary guaiacol on the shell biomineralization of abalone.(2) By the crystallization experiment in vitro, the effect of the interaction between the SM and Mg²⁺ on the crystallization of the CaCO₃ is studied; The interaction betwteen sucrose, glucose and the crystallization of CaCO₃. The result are summarized as follows:(1) The shell biomineralization process was studied by the means of "flat pearl" inserting the coverlips into the mantle cavity of Haliotis discus hannai Ino. The microstructure of the deposition on the coverlips was analyzed by scan electron microscope (SEM), the crystal phase of the deposition was analyzed by the fourier transform infrared spectroscopy (FTIR), and the ultrastructure of mantle contacting with the coverlips was observed by transmission electron microscope (TEM). During 4-88 hours after the coverlips were inserted into the mantle cavity, organic sheets firstly deposited on the coverlips regularly. The calcite sheet appeared 88 hours later, and rounded calcite deposited on the coverlips 104 hours later. There was a transition from calcite to aragonite 8 days later, and obviously aragonite tablets appeared 15 days later. Abrupt transition to the deposition of calcite again was found 27 days later. So there is a cycle of the biomineralizaion of abalone shell: calcite→aragonite→calcite. The ultrastructure of mantle was changed after the insertion of the coverlips. The ribosome disappeared and the golgi-complex decreased in the tall columnar cells 24 hours later. Large granule cells increased, and was full of secretory granule 3 days later. The newly secretion produced by the mantle epithelium had low electronic density 7 days later. It is demonstrated that the flat-pearl-culture method can simulate the shell deposition naturally. The change of the mantle ultrastructure is related to the shell deposition process.(2) Before experiment, the abalones were feed by the semipurified diet including 50mg/kg guaiacol for 40 days later. By the means of "flat pearl", the coverlips were insert into the abalone mantle cavity and feed by the same diet for 30 days. The samples including the coverlips and the abalonemantle were taken out every several days. The samples were analysed and the result was contrasted with the naturally biomineralization: The guaiacol can change the microstructure of mantel and improve the secretive capacity; The guaiacol can accelerate the deposition of abalone shell. The deposition on the coverlips experienced the change: calcite—aragonite-*calcite-*aragonite-*calcite-*aragonite during 30 days.(3 ) The SM from abalone shell was extracted using 5% acetic acid and 2 protein fractions(SM I andSM II) were separated by anion ion exchange. The reversed -phase FPLC proved the SM I was mixture and SMII is single protein. Crystallization experiment in vitro showed that SM and the fractions markedly affected CaCO3 crystallization, and all induce the deposition of calcite. There was interaction between Mg2+and the organism when Mg2+ was add into the SM solution. When Mg2+/Ca2+=1:2 or Mg2+/Ca2+=4:1, the solution induce the the formation of calcite, when Mg2+/Ca2+=1:1 or Mg2+/Ca2+=2:1, the solution can induce the deposition of aragonite.(4) According to the mechanism of biomineralization, the glucose and sucrose were used as matrix to study their effect on the biomineralization by crystallization in vitro. The glucose induced the formation of calcite and sucrose induced the formation of the aragonite, there is interaction between saccharide and CaCO3.