The Biochemical And Genetical Analysis About Isozymes Of Portunus Trituberculatus

By using the vertical polyacrylamide gel electrophoresis, ten isozymes (ADH, MDH, ME, LDH, α-AMY, GDH, SOD, SDH, EST and GOT ) in six diffetent tissues such as muscle, branchia, heart, eye(including eyestalk), liver and ovary of Portunus trituberculatus were studied. According to this, the changes in isozyme patterns during early ontogeny of Portunus trituberculatus were investigated. and the genetic diversity of Portunus trituberculatus in the East Sea were also analyzed.With the study of tissue specificity of the isozymes, it was showed that the tissue of the Portunus trituberculatus is provided with perfect system of isozymes. All of the isozymes present different degree of tissue specificity expect for SDH. Further more, the activity of the same isozyme in different tissues is also different. The tissue specificity of the isozyme showed not only the different physiological function in different tissues, but the extensity of gene expression as well.The isozyme genetic variation was investigated on the basis of tissue specificity. The expression of teen isozymes in muscle, liver and ovary was examined. The results indicated that , among 22 loci analyzed, only EST-3 is polymorphic. According to the standard of P0.99, the mean proportion of polymorphic loci of the East Sea population of Portunus trituberculatus is 4.5%. The average heterozygosity(Ho) is 0 while the expect average heterozygosity(He) is 0.007. All the results indicate that the genetic variation level of Portunus trituberculatus population is comparatively low.The changes in isozyme patterns during early ontogeny (from unfertilized eggs to the 1st stage of young crab) of Portunus trituberculatus were also investigated. Eleven isozymes ( LDH> GDH, ADH, SOD. EST, ME, MDH, SDH, GOT, ACP and a-AMY ) were separated by vertical slab polyacrylamide gel electrophoresis and then detected by specific histochemical staining. The results showed that the electrophoretograms of seven isozymes ( EST, ME, MDH, SDH, GOT, ACP and a -AMY ) exhibited obvious differences among early ontogenic stages of P. trituberculatus, and the complexity of electrophoretogram pattern tended to increase with development in most of the seven isozymic systems. The stage-specific isozymic bands can be used as the biochemical indexes to identify the specificity of certain development stage. No LDH and GDH isozymes were expressed during early ontogeny of P. trituberculatus. Both ADH and SOD isozymes had stable expression at every developmental stages of P. trituberculatus, ADH isozyme has one band, and SOD isozyme has two bands. According to the expression of isozymic bands during early ontogeny, the isozymic bands of P. trituberculatus were divided into four types. The ontogenetic polymorphism of isozyme and the isozyme activity at the 1st zoeal stage newly after hatching were also discussed in the present paper.