This study examined the effects of salinity on embryonic development, survival, and growth of the Hong Kong oyster Crassostrea hongkongensis. The embryos, larvae, and juveniles of C. hongkongensis were held in artific...This study examined the effects of salinity on embryonic development, survival, and growth of the Hong Kong oyster Crassostrea hongkongensis. The embryos, larvae, and juveniles of C. hongkongensis were held in artificial seawater at three different salinities(low, 15; medium, 23; and high, 30) to determine the optimum hatchery and nursery conditions for mass production of the seeds. Results showed that the percentage production of straight-hinged larvae from fertilized eggs was significantly lower at the high salinity than at the low- and medium-salinities(P < 0.05). The survival rates of larvae and juveniles differed significantly among the three salinity trials, with the highest survival rate observed at the low salinity(P < 0.05). The shell height of larvae was significantly larger at the low salinity than at the high and medium salinities from days 9 to 15(P < 0.05), whereas that of juveniles was significantly larger at the low salinity than at the high and medium salinities on day 70(P < 0.05). These results indicate that the larvae and juveniles of C. hongkongensis are tolerant to a wide range of salinities(15 to 30), but show better growth and survival at relatively low salinities. Thus, it is recommended to use relatively low salinities in hatchery and nursery systems for improved yields of C. hongkongensis.展开更多
Substrate is a critical environmental factor affecting the activity of bivalves. To examine the effect of the substrate component on the growth and survival of juvenile sunray surf clam(Mactra chinensis Philippi), a s...Substrate is a critical environmental factor affecting the activity of bivalves. To examine the effect of the substrate component on the growth and survival of juvenile sunray surf clam(Mactra chinensis Philippi), a series of short-term experiments were conducted using a variety of substrates with different ratios of sand to mud. The experimental group cultured without substrate showed poor survival, with all juveniles died after day 20. The juveniles cultured in mud without sand showed a lower survival rate(25.54% ± 0.40% on day 45) than those in other groups. The juveniles cultured in sand without mud, or the mixtures of sand and mud with a ratio of 1:1 and 2:1, respectively, exhibited modest survival at day 45. Maximal weight gain rate(WGR), shell length growth rate(LGR), and specific growth rate(SGR) were observed when the sand concentration was 61.97%, 77.69%, and 64.64%, respectively. As the fast growth and high survival were observed when the sand to mud ratio was 1:1(50% sand) and 2:1(67% sand), a sand concentration of more than 50% is optimal. The optimal concentration of sand in the substrate for rearing juvenile sunray surf clams was 67% which resulted in the fastest growth and highest survival. These results can be used to developing a nursery/farming technique of improving the yield of sunray surf clams.展开更多
In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam(Ruditapes philippinarum), crosses between two full-sib families including self and reciprocal crosses ...In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam(Ruditapes philippinarum), crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A×♀B(Hp varied between 10.41% and 68.27%) displayed larger heterosis than ♂B×♀A(Hp varied between 1.89% and 32.33%) did, suggesting that ♂A×♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability(GCA), special combining ability(SCA) and interaction(I) were significant in shell length(P < 0.05), indicating that both additive and non-additive genetic factors were important contributors to the growth of larvae and juveniles. The GCA for shell length of ♂A×♀B was higher than that of ♂B×♀A at both larval and juvenile stages. This confirmed that the cross between ♂A and ♀B showed great growth in shell length. In summary, the growth of Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.展开更多
In present study, the inbreeding depression(ID) of growth and survival of Manila clam(Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families(A_2, B_2, C_2, D_2, E_2, F_2, G_2, H_...In present study, the inbreeding depression(ID) of growth and survival of Manila clam(Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families(A_2, B_2, C_2, D_2, E_2, F_2, G_2, H_2 and I_2) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae(straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group(CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A_2, B_2, C_2, and D_2, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A_2 family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated(R =-0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.展开更多
The Manila clam Ruditapes philippinarum is natively distributed along the Pacific coast of Asia,where it is one of the most important bivalve species for local fisheries.This species has been intentionally introduced ...The Manila clam Ruditapes philippinarum is natively distributed along the Pacific coast of Asia,where it is one of the most important bivalve species for local fisheries.This species has been intentionally introduced due to its high adaptability to various coastal environments and is currently widely cultivated in Europe and North America.We have initiated a selective breeding program to improve the growth rate of the Manila clam since 2007,and a full-sib family with orange shell color was selected.This family features high survival but slow growth.Thereafter,two generations of mass selection were conducted in this family by 10% upward selection for faster growth.In 2011,three types of lines were produced by selecting the breeder from the second-generation of selected lines.These lines are SS(subject to three generations of selection for growth in shell length),SC(selected for the second but not the third generation),and C(randomly sampled individuals from the national population).The genetic parameters of the shell length including hR^2(realized heritability),SR(selection response),and GG(genetic gain)were analyzed.Results showed that the shell length of the SS line was significantly larger than those of the SC and C lines at all developmental stages(P<0.05).For the larval stage,the values of hR^2,SR,and GG were 0.42,0.73,and 6.66,respectively.For the juvenile stage,the values of hR^2,SR,and GG were 0.40,0.69,21.76,respectively.For grow-out stage,the values of hR^2,SR,and GG were 0.48,0.83,and 18.22,respectively.The results of hR^2 indicated the good potential of the SS line in selective breeding.The level of GG improvement was encouraging and consistent with the previous expectations.No inbreeding depressions in the shell length were observed in the SS and SC lines at all sampling days.All of the results indicate that maintaining selection pressure in successive generations may be effective in the selective breeding program of this family.展开更多
In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam i...In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam individuals(on the basis of shell length) of a full-sib family were selected as parents for the fast and slow growing lines, respectively. The difference in shell length was significant among the three lines(fast, control, and slow) tested. The sequence of shell length were fast line > control line > slow line. The responses to selection, realized heritability, and genetic gain were 0.06%–0.81%, 0.04%–0.47% and 0.58%–18.89% in the fast direction, respectively; and were 0.14%–1.27%, 0.08%–0.73%, and 0.31%–49.03% in the slow direction, respectively. The results suggested that there was a large portion of additive genetic variance affecting the growth in the full-sib family. Selection in the fast direction within the full-sib family would greatly improve the growth of R. philippinarum.展开更多
Crossbreeding is an effective approach to manage the genetic decline in aquaculture.One-way hybrids of Crassostrea sikamea(♀)and Crassostrea gigas(♂)have advantages in growth traits and adaptation to high temperatur...Crossbreeding is an effective approach to manage the genetic decline in aquaculture.One-way hybrids of Crassostrea sikamea(♀)and Crassostrea gigas(♂)have advantages in growth traits and adaptation to high temperature.Here,we used high-throughput sequencing to analyze the molecular processes in the hybrids under and after thermal stress.The hybrids were cultured in the seawater with an increasing temperature from 25℃to 40℃during 10 hours,which is regarded as the thermal stress stage.Then the temperature decreased from 40℃to 25℃within 2 h,which is regarded as the recovery stage.In this study,1293 significant diffe-rentially expressed genes(DEGs)were obtained under thermal stress,of which 576 were upregulated and 717 were downregulated,and 740 significant differentially expressed genes(DEGs)were obtained in the recovery stage,of which the number of upregulated and downregulated genes was 409 and 331,respectively.The antigen processing and presentation,NOD-like,and NF-kappa B path-ways were significantly enriched during the thermal stress stage.The MAPK and PPAR signaling pathways were significantly enrich-ed during the recovery stage.The HSP70,HSP90,and CANX genes were strongly and rapidly upregulated in the control/thermal stress groups but were slightly less upregulated in the thermal stress/recovery group.These results indicate that the innate immune system or nonspecific immunity was deployed to protect interior tissues from thermal stress.In addition,85%of the mutual DEGs were involved in bidirectional regulation(up/down or down/up)when the oysters were removed from the thermal stress to recover.This study provides preliminary insight into the molecular response of C.sikamea(♀)and C.gigas(♂)hybrids to thermal stress and provides a basis for future studies on temperature-adaptation and the possible expansion of hybrid breeding.展开更多
Ocean acidification leads to changes in physiological and immune responses of bivalves, but the eff ect on the immune enzyme activities of the Manila clam, R uditapes philippinarum, when the pH is lower than the norma...Ocean acidification leads to changes in physiological and immune responses of bivalves, but the eff ect on the immune enzyme activities of the Manila clam, R uditapes philippinarum, when the pH is lower than the normal value has not been studied in detail. In this study, experiments were conducted to determine how pH(7.4, 7.7, 8.0) affects the immune enzyme activities in the gill and hemocytes of the Manila clam. Membrane stability and phagocytosis increased with decrease of pH from 8.0 to 7.7 and then decreased at pH 7.4. The total protein content in the hemocytes and gills decreased with decreasing pH. Lysozyme content in the hemocytes increased with decreasing pH, and the diff erences were significant among the different pH groups(P < 0.05). Adenosine triphosphatase activity at pH 7.4 was significantly higher than in the other two groups, but no significant diff erence was observed between pH 7.7 and 8.0. Catalase activity decreased from pH 8.0 to 7.7 and then increased at pH 7.4, and the dif ferences were significant among the experimental groups( P < 0.05). These findings provide valuable information about the immune response of R. philippinarum to reduced water pH and insights for future research investigating exposure of bivalves to elevated CO_2 conditions.展开更多
基金supported by grants from the National Natural Science Foundation of China (31172403)the National Basic Research Program of China (2010CB126406)
文摘This study examined the effects of salinity on embryonic development, survival, and growth of the Hong Kong oyster Crassostrea hongkongensis. The embryos, larvae, and juveniles of C. hongkongensis were held in artificial seawater at three different salinities(low, 15; medium, 23; and high, 30) to determine the optimum hatchery and nursery conditions for mass production of the seeds. Results showed that the percentage production of straight-hinged larvae from fertilized eggs was significantly lower at the high salinity than at the low- and medium-salinities(P < 0.05). The survival rates of larvae and juveniles differed significantly among the three salinity trials, with the highest survival rate observed at the low salinity(P < 0.05). The shell height of larvae was significantly larger at the low salinity than at the high and medium salinities from days 9 to 15(P < 0.05), whereas that of juveniles was significantly larger at the low salinity than at the high and medium salinities on day 70(P < 0.05). These results indicate that the larvae and juveniles of C. hongkongensis are tolerant to a wide range of salinities(15 to 30), but show better growth and survival at relatively low salinities. Thus, it is recommended to use relatively low salinities in hatchery and nursery systems for improved yields of C. hongkongensis.
基金supported by the earmarked fund for Modern Agro-industry Technology Research System (CARS48)grants from the ‘863’ Project of China (2012 AA10AA400)
文摘Substrate is a critical environmental factor affecting the activity of bivalves. To examine the effect of the substrate component on the growth and survival of juvenile sunray surf clam(Mactra chinensis Philippi), a series of short-term experiments were conducted using a variety of substrates with different ratios of sand to mud. The experimental group cultured without substrate showed poor survival, with all juveniles died after day 20. The juveniles cultured in mud without sand showed a lower survival rate(25.54% ± 0.40% on day 45) than those in other groups. The juveniles cultured in sand without mud, or the mixtures of sand and mud with a ratio of 1:1 and 2:1, respectively, exhibited modest survival at day 45. Maximal weight gain rate(WGR), shell length growth rate(LGR), and specific growth rate(SGR) were observed when the sand concentration was 61.97%, 77.69%, and 64.64%, respectively. As the fast growth and high survival were observed when the sand to mud ratio was 1:1(50% sand) and 2:1(67% sand), a sand concentration of more than 50% is optimal. The optimal concentration of sand in the substrate for rearing juvenile sunray surf clams was 67% which resulted in the fastest growth and highest survival. These results can be used to developing a nursery/farming technique of improving the yield of sunray surf clams.
基金supported by the earmarked fund for Modern Agro-industry Technology Research System (CARS-48)grants from the ‘863’ Project of China (2012AA10AA400)
文摘In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam(Ruditapes philippinarum), crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A×♀B(Hp varied between 10.41% and 68.27%) displayed larger heterosis than ♂B×♀A(Hp varied between 1.89% and 32.33%) did, suggesting that ♂A×♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability(GCA), special combining ability(SCA) and interaction(I) were significant in shell length(P < 0.05), indicating that both additive and non-additive genetic factors were important contributors to the growth of larvae and juveniles. The GCA for shell length of ♂A×♀B was higher than that of ♂B×♀A at both larval and juvenile stages. This confirmed that the cross between ♂A and ♀B showed great growth in shell length. In summary, the growth of Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.
基金supported by grants from National Science Foundation of China(31502163)the fund earmarked for Modern Agroindustry Technology Research System(CARS-48)
文摘In present study, the inbreeding depression(ID) of growth and survival of Manila clam(Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families(A_2, B_2, C_2, D_2, E_2, F_2, G_2, H_2 and I_2) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae(straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group(CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A_2, B_2, C_2, and D_2, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A_2 family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated(R =-0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.
基金supported by the National Key R&D Program of China (No. 2018YFD0901404)Tianjin Agricultural Science and Technology Achievements Transformation and Promotion Project (No. 201903010)+2 种基金Tianjin Modern Agro-Industry Technology Research SystemAquaculture-Shellfish Breeding Positions (No. ITTFRS 2017013)Tianjin Major Project of Seed Science and Technology (No. 17ZXZYNC00020)Earmarked Fund for Modern Agro-Industry Technology Research System (No. CARS-49)
文摘The Manila clam Ruditapes philippinarum is natively distributed along the Pacific coast of Asia,where it is one of the most important bivalve species for local fisheries.This species has been intentionally introduced due to its high adaptability to various coastal environments and is currently widely cultivated in Europe and North America.We have initiated a selective breeding program to improve the growth rate of the Manila clam since 2007,and a full-sib family with orange shell color was selected.This family features high survival but slow growth.Thereafter,two generations of mass selection were conducted in this family by 10% upward selection for faster growth.In 2011,three types of lines were produced by selecting the breeder from the second-generation of selected lines.These lines are SS(subject to three generations of selection for growth in shell length),SC(selected for the second but not the third generation),and C(randomly sampled individuals from the national population).The genetic parameters of the shell length including hR^2(realized heritability),SR(selection response),and GG(genetic gain)were analyzed.Results showed that the shell length of the SS line was significantly larger than those of the SC and C lines at all developmental stages(P<0.05).For the larval stage,the values of hR^2,SR,and GG were 0.42,0.73,and 6.66,respectively.For the juvenile stage,the values of hR^2,SR,and GG were 0.40,0.69,21.76,respectively.For grow-out stage,the values of hR^2,SR,and GG were 0.48,0.83,and 18.22,respectively.The results of hR^2 indicated the good potential of the SS line in selective breeding.The level of GG improvement was encouraging and consistent with the previous expectations.No inbreeding depressions in the shell length were observed in the SS and SC lines at all sampling days.All of the results indicate that maintaining selection pressure in successive generations may be effective in the selective breeding program of this family.
基金supported by the grant from the Natural National Science Foundation of China (No.31502163)the fund earmarked for Modern Agro-industry Technology Research System (CARS-48)the Natural Science Foundation Grant of Tianjin (No.15JCYBJC30400)
文摘In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam individuals(on the basis of shell length) of a full-sib family were selected as parents for the fast and slow growing lines, respectively. The difference in shell length was significant among the three lines(fast, control, and slow) tested. The sequence of shell length were fast line > control line > slow line. The responses to selection, realized heritability, and genetic gain were 0.06%–0.81%, 0.04%–0.47% and 0.58%–18.89% in the fast direction, respectively; and were 0.14%–1.27%, 0.08%–0.73%, and 0.31%–49.03% in the slow direction, respectively. The results suggested that there was a large portion of additive genetic variance affecting the growth in the full-sib family. Selection in the fast direction within the full-sib family would greatly improve the growth of R. philippinarum.
基金supported by the National Natural Sci-ence Foundation of China(No.31172403).
文摘Crossbreeding is an effective approach to manage the genetic decline in aquaculture.One-way hybrids of Crassostrea sikamea(♀)and Crassostrea gigas(♂)have advantages in growth traits and adaptation to high temperature.Here,we used high-throughput sequencing to analyze the molecular processes in the hybrids under and after thermal stress.The hybrids were cultured in the seawater with an increasing temperature from 25℃to 40℃during 10 hours,which is regarded as the thermal stress stage.Then the temperature decreased from 40℃to 25℃within 2 h,which is regarded as the recovery stage.In this study,1293 significant diffe-rentially expressed genes(DEGs)were obtained under thermal stress,of which 576 were upregulated and 717 were downregulated,and 740 significant differentially expressed genes(DEGs)were obtained in the recovery stage,of which the number of upregulated and downregulated genes was 409 and 331,respectively.The antigen processing and presentation,NOD-like,and NF-kappa B path-ways were significantly enriched during the thermal stress stage.The MAPK and PPAR signaling pathways were significantly enrich-ed during the recovery stage.The HSP70,HSP90,and CANX genes were strongly and rapidly upregulated in the control/thermal stress groups but were slightly less upregulated in the thermal stress/recovery group.These results indicate that the innate immune system or nonspecific immunity was deployed to protect interior tissues from thermal stress.In addition,85%of the mutual DEGs were involved in bidirectional regulation(up/down or down/up)when the oysters were removed from the thermal stress to recover.This study provides preliminary insight into the molecular response of C.sikamea(♀)and C.gigas(♂)hybrids to thermal stress and provides a basis for future studies on temperature-adaptation and the possible expansion of hybrid breeding.
基金Supported by the National Natural Science Foundation of China(No.31502163)the General Project of Liaoning Provincial Education Department(No.L201604)the Modern Agro-industry Technology Research System(No.CARS-49)
文摘Ocean acidification leads to changes in physiological and immune responses of bivalves, but the eff ect on the immune enzyme activities of the Manila clam, R uditapes philippinarum, when the pH is lower than the normal value has not been studied in detail. In this study, experiments were conducted to determine how pH(7.4, 7.7, 8.0) affects the immune enzyme activities in the gill and hemocytes of the Manila clam. Membrane stability and phagocytosis increased with decrease of pH from 8.0 to 7.7 and then decreased at pH 7.4. The total protein content in the hemocytes and gills decreased with decreasing pH. Lysozyme content in the hemocytes increased with decreasing pH, and the diff erences were significant among the different pH groups(P < 0.05). Adenosine triphosphatase activity at pH 7.4 was significantly higher than in the other two groups, but no significant diff erence was observed between pH 7.7 and 8.0. Catalase activity decreased from pH 8.0 to 7.7 and then increased at pH 7.4, and the dif ferences were significant among the experimental groups( P < 0.05). These findings provide valuable information about the immune response of R. philippinarum to reduced water pH and insights for future research investigating exposure of bivalves to elevated CO_2 conditions.
