| The Order Euphausiacea consists of 86 or 87 species distributed over the ocean of the world, plays an important role in marine ecosystem, particularly in southern ocean, and is the key link of marine primarily productivity and higher trophic levels. Krill fisheries are relatively recent developments.47 species belonging to seven genera of two families in krill were recorded in China seas. Among them, Euphausia pacifica, Pseudeuphausia latifrons and P. sinica are dominant species that play a key role in the China sea. By means of the vertical slab polyacrylamide gel electrophoresis, genetic heterogeneity of three krill was investigated, in order to elucidate the genetic diversity and differentiation among them. 1. Genetic diversity and differentiation of E. pacificaE. pacifica were collected at eight stations in the Yellow Sea and East China Sea between 2000-2001 as part of 973 Chinese Globec. Seven enzyme systems were assayed as follow, a-l,4-glucan-4-glucaflhydrolase (E.C. 3.2.1.1, a-AMY), a-l,6-glucano-hydrolase (E.C. 3.2.1.9, R-AMY), esterase (E.C. 3.1.1.1, EST), malate dehydrogenase (E.C. 1.1.1.37, MDH), malic enzyme (E.C. 1.1.1.40, ME), lactate dehydrogenase (E.C. 1.1.1.27, LDH), and glucose phosphate isomerase (E.C. 5.3.1.9, PGI).The proportion of polymorphic loci per station ranged from 42.86 to 87.50%, the mean value over all stations was 88.89%. Ivfean expected heterozygosity per locus (He) calculated over the 9 loci analyzed ranged from 0.1457 to 0.2271, the average over all stations was 0.3140+0.2552. The effective number of alleles per locus varied between 1.2845 and 1.4165, the mean value over all stations was 1.6628?.6585.Genetic differentiation was high among the stations, the mean FST for all loci was 0.5123. The gene flow Nm was 0.2380<1, indicated that gene drift would promote thegenetic differentiation. The Nei's genetic distance(D) between the stations was 0.3383 (0.0032-0.7641), and the genetic identity was 0.7482 (0.4658-0.9968). The arrangement of the various stations on an UPGMA dendrogram on the basis of D produced two main clusters, one formed by the stations E2 and 1 -4, and the other by the remaining stations. The genetic subdivision was due to the inche variation and circulation vicariance. The stations E2 and 1-4 were located at the cold water mass area of the central Yellow Sea, which characterized by low temperature, high salinity and stable theromocline would generate a retention mechanism that promoted the formation of separate, self-supporting stocks of krill.2 Genetic diversity and differentiation of P. latifronsSpecimens of P. latifrons were collected from the East China Sea and the South China Sea. The zymogram phenotypes of aspartate aminotransferase (E. C. 2.6.1.1, AAT), alkaline phosphatase (E. C. 3.1.3.1, ALP), a-amylase (a-AMY), R-amylase (R-AMY), esterase (EST), lactate dehydrogenase (LDH), raalate dehydrogenase (MDH), malic enzyme (ME), and phosphoglweoisomerase (PGI) were scored.The proportion of polymorphic loci per station ranged from 70.00 to 75.00%, the mean value over two stations was 90.91%. Mean expected heterozygosity per locus (He) calculated over the 11 loci analyzed ranged from 0.2240 to 0.3269, the average over two stations was 0.3336?.1961. The effective number of alleles per locus varied between 1.3791 and 1.6534, the mean value over two stations was 1.6310+0.1509.The standardized variation in allele frequencies of P. latifrons populations between two stations was 0.3410, and the gene flow was 0.4832, suggesting that the magnitude of genetic differentiation between two populations was relatively high. The Nei's genetic distance between two stations was 0.2749, and the genetic identity was 0.7596. The genetic subdivision was due to the geographic barrier.3 Genetic diversity of P. sinicaThe genetic structure of P. sinica in Xiamen harbour was examined by analyzing the zymogram phenotypes of aspartate aminotransferase (AAT), alkaline phosphatase(ALP), a-amylase (o-AMY), R-amylase (R-AMY), esterase (EST), lactate deh...
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