Application of the first internal transcribed spacer(ITS-1) of ribosomal DNA as a molecular marker to population analysis in farrer''s scallop Chlamys farreri

Sequence variation of the first internal transcribed spacer of ribosomal DNA （ ITS - 1 ） was examined and its application to the study of genetic variation was explored in four populations of farter＇ s scallop Chlamys farreri. ITS - 1 fragments, with a length of about 300 bp,of 78 individuals collected from Dalian, Qingdao, Yantai in China and Korea respectively were amplified via PCR, cloned and sequenced. Intra-genomic variation was examined by sequencing several clones of single individuals. Alignment and polymorphism analysis detected 44 haplotypes and 50 polymorphic sites which consist of 30 substitutions and 20 indels, indicating a high level of polymorphisms. Sequence analysis also showed a very low level of intra-individual variation. All these features validated the feasibility of application of ITS - 1 fragment to population analysis. Polymorphism analysis showed that the Korea sample has the richest genetic variation, followed by Yantai and Qingdao samples. AMOVA （analysis of molecular variance） showed that the majority （96.26%） of genetic variation was distributed within populations and 3.74% resulted from among populations, but with P 〈 0.05 （ = 0.042）, indicating that the populations in this study have significant divergence. This output was basically concordant with the result arising from RAPD data and different from that from mitochondrial 16S rDNA sequence data. Discussion on this inconsistency was made accordingly.     

The effect of the causative algae of large-scale HAB in the East China Sea on egg hatching of Argopecten irradians, and population growth of Brachionus plicatilis and Moina mongolica

The impacts of Prorocentrum donghaiense Lu and Alexandrium catenella Balech, causative species of the large-scale HAB in the East China Sea, were studied under laboratory conditions. According to bloom densities, the effects of monoculture and mixture of the two species were examined on the egg-hatching success of Argopecten irradians Lamarck, and the population growth of Brachionus plicatilis Müller and Moina mongolica Daday. The results showed that monoculture of A. catenella had a significant inhibition on the egg hatching success of A. irradians, and the population growth of B. plicatilis and M. mongolica. The median effective densities (ED_50) inhibiting the egg hatching success of A. irradians for 24 h and the population growth of B. plicatilis and M. mongolica for 96 h were 800, 630, and 2 400 cells/cm3, respectively. Monoculture of P. donghaiense has no such inhibitory effect on the egg hatching success of A. irradians; P. donghaiense at lower suitable densities could sustain the population growth of B. plicatilis (1×104~3×104cells/cm3) and M. mongolica (2×104~5×104cells/cm3); P. donghaiense at higher densities had significantly adverse effect on the population growth of B. plicatilis (4×104~10×104cells/cm3) and M. mongolica (10×104cells/cm3). When the two algae were mixed according to bloom densities, P. donghaiense at suitable densities to some extent could decrease the toxicity of A. catenella to B. plicatilis and M. mongolica. The results indicated that the large-scale HAB in the East China Sea could have adverse effect on zooplankton, and might further influence the marine ecosystem, especially when there was also Alexandrium bloom.     

Genetic diversity and differentiation of mud crab Scylla serrata populations from southeastern China

The genetic diversity and differentiation of 6 mud crab Scylla serrata populations from southeastern China are investigated using allozyme electrophoresis. The mean number of alleles per locus population is 1.3 ± 0.1; the percentage of polymorphic loci per population is 27.3; the observed heterozygosity ranges from (0.195±0.083) to ( 0.241±0.090) and the expected heterozygosity ranges from ( 0.105±0.043 ) to ( 0.131±0.047 ). The coefficient of gene differentiation among populations is low (Fst =0.032), indicating that only 3.2 % of the total genetic diversity comes from inter-population, while the remaining 96.8 % comes from intra-population differences. The genetic distance among populations is 0.000-0.008 (the average is 0.002). Gene flow among the populations is large (Nm = 7.56).Genetic structure is very similar among 6 Scylla serrata populations.     

Comparative studies on some genetic characteristics among four large yellow croaker (Pseudosciaena crocea) populations

The genetic structure was compared among four large yellow croaker (Pseudosciaena crocea) populations, an important aquaculture species in China. RAPD and ISSR results show that the genetic distances between domestic stocks and their wild counterparts are significantly larger than those between the three wild stocks. The sequence of mtDNA cyt b shows that the three wild populations share the same sequence, with differences in the four bases from the cultured stock: two transitions [57(C-T), 291(G-A)] and two transversions [66(C-G),223(A-C)]. Cluster analysis reveals that the domestic stock has diverged from its parental wild stock [Min—Yuedong (Fujian Province—eastern Guangdong Province, China) stock]. Results demonstrate that 20 a of domestication of the Pseudosciaena crocea stock has resulted in significant genetic changes.     

Effects of β-ecdysone and polypodine-B on moulting and growth of prawn, Penaeus orientalis

Effects of the mixture of β-ecdysone and polypodine -B (2 : 1 W/W) on the moulting and growth of prawn, Penaeus orientaliss were studied in laboratory by rearing the animal with the added compound diets. The results showed that the addition of the moulting hormone (M. H) mixture to compound diets, from 1. 33× 10-6 to 30×10-6, could increase moulting activity and growth rate of the prawn to different extents, among which the 5. 33× 10-6-10. 67×10-6addition had statistically significant effects. However, 60 × 10-6 added diets caused moulting and growth inhibitions and cuticle thickening. The analyses of protein, water and ash contents of the prawn showed no remarkable differences between hormone dosed animals and the control.     

Studies on rickettsia-like organism (RLO) disease of tropical marine pearl oyster-Epidemiological investigation of RLO disease in juvenile populations of maricultured Pinctada maxima

The death which occurred in juvenile population was a severe problem in the course ofPinctada maxima artificial culture. With the methods of field investigation, histological study and statistic analyses, the epidemiological study was carried out on the disease and death in juvenile populations of Pinctada maxima in the Xinying Pearl Oyster Mariculture Farm of Lingao County (for the A, B and C batches of cultured juveniles hanged in the sea) and the Xincun Pearl Oyster Mariculture Farm of Lingshui County (for the D batch of cultured juvenile hanged in the pond), Hainan Province from November 1993 to April 1995.The results show that the deaths which occurred in juvenile populations of Pinctada maxima presented an outbreak pattern. The peak of mortality rates, in general, occurred in 4-to 6-month old pearl oyster juveniles, and the mortality rates gradully declined with the extention of pearl oyster age after cul-turing 8 months. The correlation between the mortality rates of juvenile populations and mean     

Heterosis and heritability estimates for the survival of the Pacific white shrimp (Litopenaeus vannamei) under the commercial scale ponds

The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp(Litopenaeus vannamei) for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%(UA1×UA2) to 20.53%(UA3×SIN) with an average of 0.953%. The results showed that more than half of the hybrids(51.85%) have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero(P0.05). The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.     

A growth model for a hyalid amphipod Hyale perieri in the coastal water of Alexandria (Egypt)

Abstract-The growth rate of the hyalid amphipod Hyale perieri was studied on the bases of Ikeda'sgrowth model which is based on the inter moult period (IP) and moult increament (ΔBL). To applythis approach, laboratory experiments were carried out at three temperatures regimes (15℃, 20℃,25℃) to gain accurate data of IP and BL. The total number of specimens used in this study was 86 at15℃, 24 at 20℃ and 70 at 25℃. The number of flagellar segments of both antennae of the Hyaleperieri could not be used as an index of growth (instar criterion). The obtained results indicated that,the predicted IP of the specimens was inversely related to temperature and in good agreement with theobserved values at the experimental temperatures. IP data obtained from laboratory-reared specimes arecombined with ΔBL data to establish a growth model for Hyale perieri from its release from the mar-supium (1.64 mm BL) to the maximum size (12.67 mm BL) as a function of temperature. The maxi-mum numbers of consecutive moults     

基于微卫星(SSR)分子标记的中国对虾渤海湾增殖亲虾群体及回捕群体的遗传多样性分析

Eight microsatellite markers were used to analyze genetic diversity, level of inbreeding, and effective population size of spawner and recaptured populations of Chinese shrimp(Fenneropenaeus chinensis) during stock enhancement in the Bohai Bay in 2013. A total of 254 and 238 alleles were identified in the spawner and recaptured populations, respectively, and the numbers of alleles(N_a) were 8–63 and 6–60, respectively. The numbers of effective alleles(N_e) were 2.52–21.60 and 2.67–20.72, respectively. The polymorphism information content ranged from 0.529 to 0.952. The observed heterozygosity(H_o) values(0.638–0.910 and 0.712–0.927) were lower than the expected heterozygosity(H_e) values(0.603–0.954 and 0.625–0.952), which indicated that the two populations possessed a rich genetic diversity. In 16 tests(2 populations×8 loci), 13 tests deviated from the HardyWeinberg equilibrium. F_(is) values were positive at seven loci and the inbreeding coefficients(F) of the two populations estimated by trio ML were 13.234% and 11.603%, suggesting that there was a relatively high degree of inbreeding. A certain level of inbreeding depression had occurred in the Chinese shrimp population. F_(st) values ranged from 0 to 0.059, with a mean of 0.028, displaying a low level of genetic differentiation in the two populations. Effective population sizes(3 060.2 and 3 842.8) were higher than the minimum number suggested for retaining the evolutionary potential to adapt to new environmental conditions. For enhancement activity in 2014,the ideal number of captured shrimp spawners should have ranged from 7 686 to 19 214 to maintain genetic diversity and effective population size. Further strategies to adjust the balance of economic cost, fishing effort and ideal number of shrimp spawners to maintain a satisfactory effective population size for ensuring the sustainability of Chinese shrimp are proposed.     

黄渤海带鱼(Trichiurus lepturus)渔业生物学参考点估计研究

It is important to find a reliable method to estimate maximum sustainable yield(MSY) or total allowable catch(TAC) for fishery management, especially when the data availability is limited which is a case in China. A recently developed method(CMSY) is a data-poor method, which requires only catch data, resilience and exploitation history at the first and final years of the catch data. CMSY was used in this study to estimate the biological reference points for Largehead hairtail(Trichiurus lepturus, Temminck and Schlegel) in the Yellow Sea and Bohai Sea, based on the fishery data from China Fishery Statistical Year Books during 1986 to 2012. Additionally,Bayesian state-space Schaefer surplus production model(BSM) and the classical surplus production models(Schaefer and Fox) performed by software CEDA and ASPIC, were also projected in this study to compare with the performance of CMSY. The estimated MSYs from all models are about 19.7×104–27.0×104 t, while CMSY and BSM yielded more reasonable population parameter estimates(the intrinsic population growth rate and the carrying capacity). The biological reference points of B/BMSY smaller than 1.0, while F/FMSY higher than 1.0 revealed an over-exploitation of the fishery, indicating that more conservative management strategies are required for Largehead hairtail fishery.     

Quantitative traits correlative analysis and growth comparison among different populations of bay scallop,Argopecten irradians

The shell traits and weight traits are measured in cultured populations of bay scallop, Argopecten irradians. The results of regression analysis show that the regression relationships for all the traits are significant (P<0.01). The correlative coefficients between body weight, as well as tissue weight with shell length, shell height and shell width are significant (P<0.05). But the correlative coefficients between the anterior and posterior auricle length with body weight as well as tissue weight are not significant (P>0.05). The multiple regression equation is obtained to estimate live body weight and tissue weight. The above traits except anterior and posterior auricle length are used for the growth and production comparison among three cultured populations, Duncan's new multiple range procedure analysis shows that all the traits in the Lingshuiqiao (LSQ) population are much more significant than those of the other two populations (P<0.01), and there is no significant difference between the Qipanmo (     

Effects of effective population size on the F2 growth and survival of bay scallop Argopecten irradians irradians(Lamarck)

In 2002, six cohorts ofbroodstock bay scallop Argopecten irradians irradians （Ne=1, 2, 10, 30, 50 and control） were randomly chosen from a population of bay scallop to produce offspring. After one year rearing, with the progeny matured, the similar experiment was done to produce the F2 generation. To determine the magnitude of Ne effects, the growth and survival rates in larvae and adult of six F2 groups were compared. Results showed that inbreeding depression existed not only in the Ne=1 group but also in the Ne=2 group. The growth and survival rates of the two groups were significantly lower than those of the other groups （Ne=10, 30, 50, control）, and there were no significant differences among the latter （P〉0.05）. At the same time, the amount of depression in the Ne=1 group was significantly higher than that of the Ne=2 group （P〈0.05）. These results indicated that the low effective population size （Ne）, which increases the possibility of inbreeding, could lead to some harmful effects on the offspring. So it is essential to maintain a high level of Ne in commercial seed production. Fta＇thermore, as the high fecundity of bay scallop might lead to increased inbreeding, selecting broodstock from different growout sites is recommended.     

Morphology, reproduction, ecology and isoenzyme electrophoresis of Capitella complex in Qingdao

-Morphology, reproduction, ecology and isoenzyme electrophoresis of a Capitella complex in Qingdao were examined from 1983 to 1984. We determined that the Capitella complex in Qingdao was composed of at least three sibling species: Capitella cf capitata, Capitella sp. I and Capitella sp. IT. Although these three species are very similar in morphology, they differ in: three kinds of isoenzyme electrophoresis, staining reactions, developmental pattern, larval morphology and dispersal, reproductive strategies, breeding season and population ecology. In addition, they show a series of minor quantitative variations in adult morphology, especially in number and morphology of setae. Such differences can be detected only at the population level. Some ecological data such as density, growth rate, mortality and sex distribution are also provided in this paper.     

Effect of oil pollution on gluthione and relative enzyme in oyster(Saccostrea cuculiata)

The oysters ( Saccostrea cuculiata ) were collected from four stations around Xiamen Island (Lundu Port, Xinglin Bay, Tong" an Bay, Huangcuo). The relation between the level of petroleum hydrocarbon in whole tissue and the contents of glutathione (GSH), the activity of selenium-dependent glutathione peroxidase (Se-GPx) and glutathione S-transferase (GST) in digestive gland and gill were investigated. The results showed: (1) The contents of petroleum hydrocarbon in oyster collected from four stations (Lundu Port, Xinglin Bay, Tong'an Bay, Huangcuo) were 380.68, 112.34, 27.31, 20.37μg/g wet weight, respectively; (2) the activity of Se-GPx and GST in digestive gland was lower than that in gill, and the content of GSH seemed reversibly; (3) among the four stations, both Se-GPx and GST activity of digestive gland and gill in Saccostrea cuculiata sampled from the four stations showed a good correlation with whole tissue petroleum hydrocarbon, could be as biomarkers of sea oil pollution.     

三个文蛤家系双列杂交设计在两种环境下的配合力及杂种优势分析

A 3×3 complete diallel cross comprising three families of the clam Meretrix meretrix(P1, P2 and P3) was used to determine the combining ability of parental families and heterosis of F1 under indoor and openair environments for growth traits. Analysis of variance for shell length and whole body weight indicated highly significant cross effects, environment effects and the interaction of cross by environment. General combining ability(GCA) and specific combing ability exhibited great variation among crosses and between two environments. Pooled over environments, P2 was the top combiner among the three parental families for both traits studied. The cross of P1 and P3 had the highest SCA. Additionally, significant reciprocal effects were observed. For individual environment, about half of the crossbred combinations showed favorable Mid-parent heterosis(MPH)(1%) for the shell length and whole body weight. Our data has shown that non-additive genetic and reciprocal effects constituted the major sources of genetic variation for both shell length and whole body weight, which indicates that crossbreeding among selective families could further explore the heterotic effects.     

Growth performance of the clam, Meretrix meretrix, breedingselection populations cultured in different conditions

A breeding-selection program for the clam,Meretrix meretrix,was conducted since 2004.Two of the selection populations were generated with the shell color pattern as an additional selection criterion and named as SP(purple stripes)population and SB(black dots)population.The third-generation SP and SB populations(08G3SP and 08G3SB,respectively)were cultured at two commercial clam farms and a nursery pond and their shell lengths were compared.08G3SB clams had significantly larger sizes than 08G3SP clams at commercial clam farms(p<0.05),yet 08G3SB individuals were significantly smaller than 08G3SP individuals at the nursery pond(p<0.05).Then,we examined the growth of the fourth-generation SP and SB populations(10G4SP and 10G4SB,respectively)at a commercial farm,and found that the shell lengths of the 10G4SB clams increased at a significantly higher growth rate than the 10G4SP clams(p<0.05)from May to September,when the water temperature was between 24.2–27.5 C,while 10G4SB lost the growth advantage in the other months.These results indicated that SP and SB populations responded differently to environmental factors,so it is beneficial for the clam farmers to select a suitable population according to the culture environment.Furthermore,a diallel mating of the SB and SP populations was designed to investigate whether their hybrid population would show heterosis.However,the heterosis was not shown in this study,which might result from the slight genetic divergence between SB and SP populations.     

Genetic relationship between Neobenedenia girellae and N. melleni inferred from 28S rRNA sequences

The fragments of 350 bp in 28S rRNA from the closely related monogenea of trematoda, Neobenedenia girellae and N. melleni are obtained by polymerase chain reaction (PCR) amplified using a couple of special primers and then sequenced. The results show that the comparison of 28S rRNA sequences, with only a base varying in 337 bp accounting for 0.3% genetic difference, from the relative species N. girellae and N. melleni parasitized on the different fishes in different farms displays that they possess a very high genetic similarity of 99.7%, higher than that of 99.41% for the single species N. melleni sampled in different areas, and the intraspecific divergence of N.melleni is 0.59%. Meanwhile, the interspecific differences between the two Neobenedenia and three Benedenia (i.e., B. lutjani, B. rohdei and B. seriolae) range from 2.08% tol 1.73%. In addition, UPGMA and MP molecular phylogenetic trees are constructed and proved to be consistent with each other. Though the morphological characteristics and the results of genetic diversity for the two Neobenedenia show a high similarity, whether they belong to a single species or not are still undefined, and the more genes of them should be further investigated, in combination with the systematical and detailed morphological study.     

中国近海浮游桡足类中华哲水蚤（Calanussinicus Brodsky）的分子系统地理学和种群遗传结构研究

Planktonic copepod Calanus sinicus is the dominant meso-zooplankton in the Northwest Pacific Ocean. To better understand its population dynamics and phylogeographic patterns, 243 C. sinicus individuals were collected from seven locations across the shelf waters of China and its population genetics was studied by mitochondrial DNA cytochrome oxidase I(mtCOI) sequences analyses. Thirty-nine different sequences, or haplotypes, were detected with moderate haplotype diversity(h=0.749) and low nucleotide diversity(π=0.003) for all populations. The evolutionary divergence between geographic populations varied from 0.24% to 0.37%, indicative of very limited genetic differentiation. Visualized minimum spanning network(MSN) and phylogenetic analysis of all the detected haplotypes did not reveal any clear phylogeographic pattern. Furthermore, AMOVA data showed no significant spatial population differentiation existed among the individuals collected across China shelf waters. Pairwise FST values showed that population collected from northwest of the East China Sea(ECS) displayed a low difference to other populations. Mismatch distribution analyses and neutrality tests indicated that C. sinicus might undergo a demographic/population expansion. No significant population genetic structuring was detected, indicating an extensive gene flow among the C. sinicus populations. Our results provide molecular evidence for the hypothesis that C. sinicus in the northwestern South China Sea in winter is transported from the East China Sea and the Yellow Sea by the China Coastal Current during the northeast monsoon period.