Development of an Improved Automatic Chromosome Manipulation System and Optimization of Related Parameters for Pacific Oyster, Crassostrea gigas

This paper examines two major works, (1) improvement in the design of automatic manipulation system for the complicated chromosomal manipulation of shellfish, and (2) investigation of the optimum parameters needed for automatic chromosome manipulation system in oyster based on species-specific characteristics. High quality experimental material for ideal fertilization and hatching rates of eggs are highly desired for follow-up trials on chromosome manipulation. The experiments to optimize parameters exclude the use of functional chemicals for induction of triploid or tetraploid with the hope that the automation procedure will not cause any unnecessary damage. Only when high hatching rates of eggs is achieved using the automatic manipulator, that this improved system can be used for follow-up treatments on chromosome manipulation. Results indicate that fertilization should be performed within 30 minutes after the oyster eggs were stripped and kept submerged in sea water. Any longer delay should be avoided. On the other hand, air exposure of unfertilized eggs within 90 min was considered to be acceptable in the design of the automatic manipulation system. Hatching rates in individual subgroups using drum speeds of 100, 200, or 300 rpm combined with pump flows of 2.4, 5.8 or 7.6 liter/min for 20 min or 40 min were not significantly different. It was not recommended to adopt a drum speed of 300 rpm for manipulating oyster fertilized eggs if a pump flow of 2.4 liter/min operating for 20 and 40 min were desired because an averaged hatching rate at a drum speed of 300 rpm was significantly lower than that at 200 rpm. Similarly, a pump flow of 7.6 liter/min should be avoided because an averaged hatching rate from three drum speeds at a pump flow of 7.6 liter/min was significantly lower than that at 5.8 liter/min. Chromosome manipulated shellfish are not related with gene modification and thus are accepted by the market. Therefore it is reasonable to encourage the related enterprise so that value-added product of shellfish can be continuously produced. Improved automation in any manipulation protocol has been further enhanced for the sake of saving energy, saving time, avoiding man-made mistakes, and raising the replication of anticipated results. It possesses the potential of international marketing.