ISOZYMES VARIATION OF CLARIAS-MACROCEPHALUS FROM 4 LOCATIONS IN THAILAND

Fourteen enzymes or protein were assayed in four natural populations o f Clarias macrocephalus collected from different parts of Thailand; no rth (Chiangrai), central (Prachinburi) and south (Pattani and Yala). S tarch-gel electrophoresis followed by histochemical staining were cond ucted and resulted in 19 loci resolved. Twelve loci (sAAT, GAPDH-1*, 2, IDHP*, LDH-1*, 2*, sMDH-1*, ME-1 2*, GPI*, MPI* and PROT*) were mo nomorphic while seven of them were polymorphic which included EST, FH , sMDH-2*, ME-3*, PGM*, PGDH* and sSOD*. Observed heterozygosity were 0.080, 0.076, 0.038 and 0.050 respective to Chiangrai, Prachinburi, P attani and Yala population. Genetic distance revealed two population g roups, which were Chiangrai-Prachinburi and Pattani-Yala group and gen etic distance was larger within the first group than those within the second group.